Imidazopyrimidine-based multimetallic catalysts

Abstract

Disclosed is a material composition in the form of an imidazopyrimidine-based ligand, method of synthesis of said ligand and the ligand used to form bimetallic complexes in which the two metals are in close proximity which can be utilized as catalysts in chemical reactions, as generally and as specifically described herein.

Description

IMIDAZOPYRIMIDINE-BASED MULTIMETALLIC CATALYSTSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Prov. Pat. App. No: 63 / 628,379 filed on 19 July 2023, the entirety of which is hereby incorporated by reference.BACKGROUND

[0002] 1. Field of the discovery. Embodiments of the disclosure presented herein relate generally to a material composition of an imidazopyrimidine-based ligand, method of synthesis of said ligand, and usage of the ligand to form a metal complex which can be utilized as a catalyst in chemical reactions, as generally and as specifically described herein.

[0003] 2. Background information. Metal-containing complexes have been used as catalysts in various organic transformations. These reactions have been demonstrated to be one of the most powerful tools for the synthesis of functional molecules in the fields of biological, pharmaceutical, and material science. While mononuclear complexes (complexes containing a single metal atom) have been studied extensively and applied in various fields and disciplines, bimetallic or multimetallic systems have received far less attention. Bimetallic complexes are capable of unique organic transformations, high selectively, and can have increased reactivity when compared to analogous monometallic complexes. As bimetallic systems continue to be investigated, the ability to tune key parameters relies on the diversity of binucleating ligands.

[0004] Bimetallic complexes containing two metals in close proximity are increasingly studied for their catalytic properties and as scaffolds for mechanistic studies into bimetallic catalyzed processes. Within catalysis, these complexes are capable of unique organic transformations, high selectivity, and can have increased reactivity when compared to analogous monometallic complexes. In fact, bimetallic intermediates in organic transformations have been identified such as in copper-catalyzed azide-alkyne cycloadditions, or in the palladium-catalyzed halogenation of benzo[A]quinoline. In addition to catalysis, these well-defined bimetallic complexes have been used to elucidate bimetallic systems in heterogeneous catalysis, enzyme-catalyzed processes, or in reaction intermediates.

[0005] The catalytic properties of these complexes arise from the enforced proximity of the two metals, allowing for metal-metal cooperativity and synergy. Many multidentate binucleatingligands that provide a small, rigid pocket for the metals to bind to have been explored. Early work in the 1970s and 1980s demonstrated the ability of 1,8-naphthyridine and its 2,7-disubstituted derivatives such as 2,7-dimethyl-l,8-naphthyridine and 2, 7-bis(2-pyridyl)- 1,8-naphthyridine (bpnp) to form bimetallic complexes, such as dirhodium and dicopper complexes. Since then, the 1,8-naphthyridine motif has become a privileged motif, with many 2,7-disubstituted 1,8- naphthyridine ligands developed. Representative examples includePrNDI, DPEN, DPFN, andPrPNNP, used in several bimetallic systems, such as in redox catalysis with a low-valent dinickel complex, heterogeneous catalyst modeling with a dicobalt complex, and dihydrogen activation using a dicopper complex, respectively (FIG. 1 A).

[0006] As bimetallic systems continue to be investigated, the ability to tune key parameters relies on the diversity of binucleating ligands. In this regard, 1,8-naphthyridine-based ligands are differentiated only by variations to the ligand side arms and require differentiated side arms to synthesize unsymmetrical 1,8-naphthyridine-based ligands, given the symmetry of 1,8- naphthyridine. Additionally, metal-metal distance is a crucial parameter for catalysis and active site modeling, with the range of metal-metal distances in 1,8-naphthyridine-based ligands limited to between 2.5-4 A. It is also worth noting the synthetic route to 1,8-naphthyridine-based ligands requires the use of pre-functionalized 2,7-disubstitued 1,8-naphthyridine reagents, which aren’t widely available and can be difficult to synthetically access.

[0007] Further, most existing binucleating ligand designs require synthetic strategies that are complex, low-yielding, and often not environmentally benign. Thus, there is a continued need for ligand synthesis, particularly for bi- or multimetallic ligands that offer increased yields and decreased environmental impact.SUMMARY

[0008] Disclosed are ligands based on the imidazopyrimidine motif that is capable of binding with two (or more) metals with electronically distinct binding pockets. The imidazopyrimidine motif was selected for its convenient synthesis, inherent asymmetry, and the increased electron donating ability. The synthesis of ligand, 2,7-di(pyridin-2-yl)imidazo[l,2-a]pyrimidine (dpip), was completed through the condensation of the corresponding 2-aminopyrimidine and a-bromo ketone, a generalized approach that would allow for convenient modifications without alterations to the synthetic route.

[0009] Disclosed, in various embodiments, is a material composition of an imidazopyrimidine- based ligand, method of synthesis of said ligand, and usage of the ligand to form a metal complex which can be utilized as a catalyst in chemical reactions. This disclosure describes the synthesis of unsymmetric ligand 2,7-di(pyridin-2-yl)imidazo[l,2-a]pyrimidine (dpip) that is achieved in four steps on a multi-gram scale in an overall 54% yield, with possible reduction in synthetic steps due to the commercial availability of some intermediates.

[0010] In further embodiments, the method of ligand synthesis is scalable, low cost, high yielding, and potentially environmentally friendly. It allows for the incorporation of different pendant ligands including pyridines, imines, bipyridine, phosphine etc. The examples notwithstanding, the pendant groups may be any possible functional group. The imidazopyrimidine motif can increase the electron donating ability of the ligand due to resonance contributions from the fused nitrogen, resulting in stronger coordination of the bound metals and increasing electron density at the metal centers.

[0011] Catalysts produced with the ligand are inherently unsymmetrical and different metals (Cu, Ni, Pd, Co, Fe, Rh, Ru etc.) can be incorporated including those with different sizes and coordination preferences. The ability to incorporate two different metals unsymmetrically enables the design of catalysts with unique properties which leads to a broader range of applications.

[0012] Certain embodiments provide for a composition. The composition may comprise an imidazopyrimidine-based ligand configured to form a metal complex or catalyst. In certain embodiments the imidazopyrimidine-based ligand is 2,7-di(pyridin-2-yl)imidazo[l,2- a]pyrimidine (dpip). In still other embodiments the the imidazopyrimidine-based ligand is the compound of FIG. 6 wherein, Mi and M2 is a transition metal independently selected from the group of transition metals of the periodic table (i.e., Groups 3-12); wherein, L is a small molecule ligand; and, wherein, n is an integer based on the number required to complete the outer valency of the metal. In still other embodiments, L is selected from the group: halide, CO, perchlorate, sulphate, carbonate, H2O, MeOH, MeCN, carboxylates such as trifluoroacetate, acetate, and the like; and n is 0-3. In still other embodiments, (L)nis a second or third equivalent of the ligand of with associated R1-R5 groups.

[0013] In still other embodiments, the imidazopyrimidine-based ligand is selected from the group consisting of compounds (A), (B), and (C) from FIG. 8. In certain embodiments, Mi and M2 is a transition metal independently selected from the group of transition metals of the periodic table(i.e., Groups 3-12); wherein, L is a small molecule ligand; and, wherein, n is an integer based on the number required to complete the outer valency of the metal. In still other embodiments, L is selected from the group: halide, CO, perchlorate, sulphate, carbonate, H2O, MeOH, MeCN, carboxylates such as trifluoroacetate, acetate, and the like; and n is 0-3. In still other embodiments, (L)nis a second or third equivalent of the ligand of with associated R1-R8 groups.

[0014] For the embodiments disclosed, R3 / R4 / R5 / R may be any combination of R1 / R2 and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, cycloalkyl, acyl, and the like. R1 / R2 may also be any of the compounds listed. In still other embodiments, R1 / R2 is any combination of R as exemplified by compounds (I) though (XXXI I) (presented in FIG. 7 A and FIG. 7B) and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, cycloalkyl, acyl, and the like.

[0015] In certain embodiments, X is a ps-bridging ligand selected from the group comprising: OH, O, halide, S, SH, and the like.

[0016] Finally, certain embodiments provide for a method of producing compositions such as those herein disclosed. Embodiments of the method may include the steps of: providing an imadazopyrimidine containing ligand, one or more metal salts, and one or more optional small molecule ligands; combining the imadazopyrimidine containing ligand, one or more metal salts, and one or more optional small molecule ligands to form a first mixture; dissolving the first mixture in a solvent, forming a second mixture; bringing the second mixture to at least a first temperature while stirring, forming a crude metallic complex; and, working up the crude metallic complex to provide a purified metallic complex

[0017] The preceding general areas of utility are given by way of example only and are not intended to be limiting on the scope of the present disclosure and appended claims. Additional objects and advantages associated with the compositions, methods, and processes of the present invention will be appreciated by one of ordinary skill in the art in light of the instant claims, description, and examples. For example, the various aspects and embodiments of the invention may be utilized in numerous combinations, all of which are expressly contemplated by the present description. These additional advantages objects and embodiments are expressly included within the scope of the present invention. The publications and other materials used herein to illuminatethe background of the invention, and in particular cases, to provide additional details respecting the practice, are incorporated by reference.BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate several embodiments of the present disclosure; and, together with the description, serve to explain the principles of the disclosure. The drawings are only for the purpose of illustrating an embodiment of the invention and are not to be construed as limiting the disclosure. Further objects, features and advantages of the disclosure will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the invention, in which:

[0019] FIG. 1A. presents representative examples of prior 1,8-naphthyridine-based ligands. FIG. IB presents an imidazopyrimidine-based ligand. FIG. IB presents the motif of the novel imidazopyrimidine-based ligand. Dotted box in both FIG. 1A and FIG. IB is for illustration purposes only and highlights the differing motifs of the ligands.

[0020] FIG. 2 presents Scheme 1, a means of synthesis of dpip.

[0021] FIG. 3 presents Scheme 2, a means of synthesis of bimetallic complexes 4-6.

[0022] FIG. 4 presents the X-ray structure of complex 5 (ellipsoids at 30% probability) (FIG.4A), unsymmetric unit of 5 (FIG. 4B). Hydrogen atoms were omitted for clarity and the counterion was omitted (FIG. 4A).

[0023] FIG. 5A. presents the X-ray structure of complex 6 (ellipsoids at 30% probability). Cocrystallized solvent molecules and hydrogens atoms were omitted for clarity. FIG. 5B. presents the X-ray structure of an asymmetric unit of complex 4 (left), and an X-ray structure of complex 4(right). Ellipsoids are at a 30% probability. Disordered molecules and hydrogen atoms were omitted for clarity.

[0024] FIG. 6 is an example embodiment of a ligand motif in conformance with the principles articulated herein.

[0025] FIG. 7A and FIG. 7B highlight acceptable R1 / R2 combinations. Those of skill in the art will readily be able to identify further acceptable combinations with the provided examples as guides. FIG. 7A presents example compounds (I) through (XXI). FIG. 7B presents example compounds (XXII) through (XXXII).

[0026] FIG. 8 presents three (3) embodiments, compounds (A), (B), and (C), of ligands in conformance with the principles articulated herein.

[0027] FIG. 9 presents a schematic overview for a generalized method of synthesizing embodiments according to the disclosure.

[0028] FIG. 10 presents Scheme 3, a means of synthesis of Pd(dpip)(C>2CCF3)2.

[0029] FIG. 11 presents Scheme 4, a means of synthesis of Nis(dpip)(p-OH)(O2CCF3)5(CH3CN)(H2O).

[0030] FIG. 12 presents Scheme 5, a means of synthesis of Co3(dpip)(p-OH)(O2CCF3)5(CH3CN)2.

[0031] FIG. 13 presents Scheme 6, a means of synthesis of [Cu2Ni2(dpip)2(p-OH)2(O2CCF3)5(H2O)2][(O2CCF3)].

[0032] FIG. 14 presents Scheme 7, a means of synthesis of CuNi2(dpip)(p-OH)(O2CCF3)5(H2O).DETAILED DESCRIPTION

[0033] Disclosed is a new class of bi- or multimetallic ligand capable of forming novel complexes that can offer unique organic transformations, high selectivity, and increased reactivity. The following detailed description is merely exemplary in nature and is not intended to limit the disclosure or the application and uses of the subject matter as described herein. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

[0034] While various embodiments of the present disclosure are described herein, it will be understood by those skilled in the art that such embodiments are provided by way of example only. It will be understood by those skilled in the art that numerous modifications and changes to, and variations and equivalent substitutions of, the embodiments described herein can be made without departing from the scope of the disclosure. It is understood that various alternatives to the embodiments described herein may be employed in practicing the disclosure, and modifications may be made to adapt a particular structure or material to the teachings of the disclosure. It is also understood that every embodiment of the disclosure may optionally be combined with any one or more of the other embodiments described herein which are consistent with that embodiment.

[0035] Where elements are presented in list format e.g., in a Markush group), it is understood that each possible subgroup of the elements is also disclosed, and any one or more elements can be removed from the list or group.

[0036] It is also understood that, unless clearly indicated to the contrary, in any method described or claimed herein that includes more than one act or step, the order of the acts or steps of the method is not necessarily limited to the order in which the acts or steps of the method are recited, but the disclosure encompasses embodiments in which the order is so limited.

[0037] It is further understood that, in general, where an embodiment in the description or the claims is referred to as comprising one or more features, the disclosure also encompasses embodiments that consist of, or consist essentially of, such feature(s).

[0038] It is also understood that any embodiment of the disclosure, e.g., any embodiment found within the prior art, can be explicitly excluded from the claims, regardless of whether the specific exclusion is recited in the specification.

[0039] Headings are included herein for reference and to aid in locating certain sections. Headings are not intended to limit the scope of the embodiments and concepts described in the sections under those headings, and those embodiments and concepts may have applicability in other sections throughout the entire disclosure.

[0040] All patent literature and all non-patent literature cited herein are incorporated herein by reference in their entirety to the same extent as if each patent literature or non-patent literature were specifically and individually indicated to be incorporated herein by reference in its entirety.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

[0042] Where a range of values is provided, it is understood that each intervening value between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding both of those included limits are also included in the invention.

[0043] The articles "a" and "an" as used herein and in the appended claims are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article unless the context clearly indicates otherwise. By way of example, "an element" means one element or more than one element.

[0044] The term “exemplary” as used herein means “serving as an example, instance or illustration”. Any embodiment or feature characterized herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or features.

[0045] The phrase "and / or," as used herein in the specification and in the claims, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and / or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and / or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and / or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

[0046] As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e., "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of."

[0047] In the claims, as well as in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving," "holding," "composed of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to.Only the transitional phrases "consisting of and "consisting essentially of shall be closed or semiclosed transitional phrases, respectively.

[0048] As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from anyone or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a nonlimiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and / or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. Likewise, in a similar vein, the phrase “and the like” when included as part of a list is intended to convey that while the list is inclusive it is not necessarily exhaustive but those of skill in the art recognizing the guideposts provided in the listing have no problems recognizing specific compounds that fit within the more broadly disclosed classes. The phrase “and the like” explicitly recognizes those molecules and compounds, often too numerous to list, that fit within the disclosed parameters.

[0049] It should also be understood that, in certain methods described herein that include more than one step or act, the order of the steps or acts of the method is not necessarily limited to the order in which the steps or acts of the method are recited unless the context indicates otherwise.

[0050] The term “about” or “approximately” means an acceptable error for a particular value as determined by one of ordinary skill in the art, which depends in part on how the value is measured or determined. In certain embodiments, the term “about” or “approximately” means within one standard deviation. In some embodiments, when no particular margin of error (e.g., a standard deviation to a mean value given in a chart or table of data) is recited, the term “about” or “approximately” means that range which would encompass the recited value and the range which would be included by rounding up or down to the recited value as well, taking into accountsignificant figures. In certain embodiments, the term “about” or “approximately” means within 10% or 5% of the specified value. Whenever the term “about” or “approximately” precedes the first numerical value in a series of two or more numerical values or in a series of two or more ranges of numerical values, the term “about” or “approximately” applies to each one of the numerical values in that series of numerical values or in that series of ranges of numerical values.

[0051] Whenever the term “at least” or “greater than” precedes the first numerical value in a series of two or more numerical values, the term “at least” or “greater than” applies to each one of the numerical values in that series of numerical values.

[0052] Whenever the term “no more than” or “less than” precedes the first numerical value in a series of two or more numerical values, the term “no more than” or “less than” applies to each one of the numerical values in that series of numerical values.

[0053] As used herein the phrase “second or third equivalent” refers to a second or third instance of a ligand forming a metal complex and / or catalyst. For example, one or more additional copies of a ligand disclosed herein may be joined together. Thus a “first” ligand may be joined with “second” and “third” equivalents to form a complex wherein the ligand is triply repeated.

[0054] Abbreviations: bpnp 2,7-bis(2-pyridyl)-l,8-naphthyridine dpip 2,7-di(pyridin-2-yl)imidazo[l,2-a]pyrimidine

[0055] In view of the difficult limitations imposed when working with 1,8-naphthyridine- based ligands as above discussed, a ligand with a unique motif was developed: 2,7-di(pyridin-2- yl)imidazo[l,2-a]pyrimidine (dpip) (FIG. IB). The imidazopyrimidine motif was selected for several reasons, including its convenient synthesis, inherent asymmetry, and the increased electron donating ability. The synthesis of dpip was envisioned through the condensation of the corresponding 2-aminopyrimidine and a-bromo ketone, a generalized approach that would allow for convenient modifications without alterations to the synthetic route. Furthermore, advantageously, the imidazopyrimidine motif is unsymmetrical, therefore imidazopyrimidine- based ligands would inherently contain differentiated binding pockets with different affinities for metals. Lastly, it was envisioned that the imidazopyrimidine motif would increase the electron donating ability of the ligand due to resonance contributions from the fused nitrogen, resulting in stronger coordination of the bound metals and increasing electron density at the metal centers.

[0056] Below further taught and described is the synthesis and characterization of dpip as well as the dicopper, dipalladium, and dinickel complexes of dpip. All bimetallic complexes were characterized by NMR, high-resolution electrospray ionization mass spectrometry (ESI-HRMS), and X-ray crystallography.

[0057] Embodiments of the disclosure may be further described and characterized by the following numbered statements:

[0058] In any aspect or embodiment described herein, the disclosure provides a composition, comprising: an imidazopyrimidine-based ligand configured to form a metal complex or catalyst.

[0059] In any aspect or embodiment described herein, the imidazopyrimidine-based ligand is 2,7-di(pyridin-2-yl)imidazo[l,2-a]pyrimidine (dpip).

[0060] In any aspect or embodiment described herein, the imidazopyrimidine-based ligand is the compound shown in FIG. 6. Wherein, Mi and M2 is a transition metal independently selected from the group of transition metals of the periodic table (i.e., Groups 3-12). Wherein, L is a small molecule ligand. Wherein, n is an integer based on the number required to complete the outer valency of the metal.

[0061] In any aspect or embodiment described herein, the imidazopyrimidine-based ligand is selected from the group consisting of compounds (A), (B), and (C) as presented in FIG. 8. Wherein Mi, M2, and M3 are transition metals independently selected from the group of transition metals of the periodic table (i.e., Group 3-12). Wherein, L is a small molecule ligand. Wherein, n is an integer based on the number required to complete the outer valency of the metal.

[0062] In any aspect or embodiment described herein, the imidazopyrimidine-based ligand is 2,7-di(pyridin-2-yl)imidazo[l,2-a]pyrimidine (dpip).

[0063] In any aspect or embodiment described herein, the dpip is synthesized according to the process of scheme 1.

[0064] In any aspect or embodiment described herein, the imidazopyrimidine-based ligand is a multi-metallic complex.

[0065] In any aspect or embodiment described herein, the multi-metallic complex is synthesized according to scheme 2.

[0066] In any aspect or embodiment described herein, the L is selected from the group: halide, CO, perchlorate, sulphate, carbonate, H2O, MeOH, MeCN, carboxylates such as trifluoroacetate, acetate, and the like; and n is 0-3.

[0067] In any aspect or embodiment described herein, (L)nis a second or third equivalent of the ligand of any of statements 1-3 with associated R1-R5 or R1-R8 groups.

[0068] In any aspect or embodiment described herein, R3 / R4 / R5 / R is any combination of R1 / R2 and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, cycloalkyl, acyl, and the like.

[0069] In any aspect or embodiment described herein, R1 / R2 is any compound from statement 10.

[0070] In any aspect or embodiment described herein, R1 / R2 is any combination of R as exemplified by compounds (I) though (XXXII) and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroaryl alkyl, cycloalkyl, acyl, and the like.

[0071] In any aspect or embodiment described herein, X is a ps-bridging ligand selected from the group comprising: OH, O, halide, S, SH, and the like.

[0072] In any aspect or embodiment described herein, the disclosure provides a method, of producing a composition according to any of the above statements, comprising: providing an imadazopyrimidine containing ligand, one or more metal salts, and one or more optional small molecule ligands; combining the imadazopyrimidine containing ligand, one or more metal salts, and one or more optional small molecule ligands to form a first mixture; dissolving the first mixture in a solvent, forming a second mixture; bringing the second mixture to at least a first temperature while stirring, forming a crude metallic complex; and, working up the crude metallic complex to provide a purified metallic complex.

[0073] RESULTS AND DISCUSSION

[0074] Synthesis and Characterization of dpip

[0075] The synthesis of dpip was achieved on a multi-gram scale in four steps in an overall54% yield (FIG. 2 - Scheme 1). The preparation of compounds 1-3 was achieved using previously reported procedures. It is worth noting the synthetic steps can be reduced given the commercial availability of compounds 1 and 3. The final step is a condensation and cyclization reaction, which results in the formation of protonated dpip as a precipitate. Filtration of the precipitate followed by a basic workup yields dpip. Light-yellow solid dpip is sparingly soluble in most organic solvents, including acetonitrile, methanol, and dimethyl sulfoxide, with moderate solubility in di chloromethane and chloroform. The1H NMR spectrum reveals the imidazopyrimidine protonsas a set of doublets at 6 = 8.54 and 8.17 ppm and a singlet at 6 = 8.28 ppm. Protons at the same position on each pyridyl ring are closely spaced in the aromatic region, such as at 6 = 7.39 and 7.30-7.24 ppm, 6 = 8.76-8.67 and 8.63 ppm, and 6 8.76-8.67 and 8.40 ppm. The remaining protons overlap to form the multiplet at 6 = 7.91-7.79 ppm. Despite attempts in CDCh, CD3CN, and (CD3)2SO, dpip was too insoluble to record a13C NMR spectrum. ESI-HRMS was able to further confirm the identity of dpip, with the spectrum containing a single peak at m / z = 274.1084, consistent with the formula of [dpip + H]+.

[0076] Synthesis and Characterization of Cu2(dpip)( dDH)(CF3COO)3 (4).

[0077] The synthesis of 4 was achieved by combining dpip with two equivalents of Cu(OAc)2H2O in a methanol / trifluoroacetic acid solution at room temperature for 2 hours (FIG. 3. Scheme 2). The resulting green precipitate was filtered and washed with a diethyl ether / acetonitrile (2: 1) mixture to yield 4 in excellent yield (92%). Complex 4 has good solubility in methanol, with moderate solubility in solvents such as acetonitrile and acetone. The paramagneticXH NMR spectrum of 4 revealed eleven peaks present between 6 = 69.65-9.50 ppm. The two most downfield peaks at 6 = 69.65 and 63.84 ppm are broadened and likely correspond to the proton on each pyridyl ring that is close in distance to the copper centers. Conversely, the two most downfield peaks at 6 = 9.76 and 9.50 ppm likely correspond to each pyridyl proton that is farthest in distance from the copper centers. The remaining peaks are present between 6 = 33.03- 19.86 ppm. The ESI-HRMS spectrum of 4 in acetonitrile contains several peaks, notably a peak at m / z = 641.9330 which is consistent with the formula of [Cu2(dpip)(p-OH)(CF3COO)2]+. The other peaks include acetonitrile adducts such as a peak at m / z = 284.9883 which is consistent with the formula of [Cu2(dpip)(p-OH)(CF3COO)(MeCN)]2+and a peak at m / z = 166.0054 which is consistent with [Cu2(dpip)(p-OH)(MeCN)2]3+. A peak corresponding to a dimer of 4 is present at m / z = 1396.8431 which is consistent with [Cu4(dpip)2(p-OH)2(CF3COO)s]+. Additionally, simulated isotopic distributions were in good agreement with each peak above described.

[0078] Presented in FIG. 5B is the X-ray structure, confirmed by single-crystal X-ray diffraction analysis, of an asymmetric unit of complex 4 (left), and an X-ray structure of complex 4(right). Ellipsoids are at a 30% probability. Disordered molecules and hydrogen atoms were omitted for clarity, k The copper atoms and dpip are coplanar, having bite angles of 79.92(17)° for N(l)-Cu(l)-N(2) and 80.19(17)° for N(3)-Cu(2)-N(4). The X-ray structure is a dimer, with Cu(2) coordinated to 0(1)’ resulting in Cu(2) being six-coordinate and Cu(l) being five-coordinate. The coordination environment of Cu(l) is best described as distorted square pyramidal given the calculated geometry index (T) of 0.25. The base of the square pyramid in Cu(l) consists of N(l) and N(2) from dpip, 0(1) from the bridging hydroxide, and 0(2) from a trifluoroacetate, while the apical site consists of 0(6) from another trifluoroacetate. The coordination environment of Cu(2) is best described as distorted octahedral, with the equatorial plane consisting of dpip nitrogens N(3) and N(4), 0(1) from the bridging hydroxide, and 0(4) from a molecule of trifluoroacetate. The apical sites are composed of 0(7) from a trifluoroacetate molecule and the bridging hydroxide 0(1)’ from a second molecule of 4. The distorted octahedral geometry is evident by the elongated apical bond lengths [Cu(2)-O(7) 2.613(5) A and Cu(2)-0(l)’ 2.506(3) A] compared to the equatorial bond lengths [1.931(3)-2.017(4) A], in addition to the apical bond angle of 165.35(11)°. The distance between Cu(l) and Cu(2) is 3.4821(9) A, which is greater than the analogous 1,8-naphthyridine- based dicopper distance in [Cu2(bpnp)(p-OH)(CF3COO)3] [3.0937(4) A],

[0079] Synthesis and Characterization of [Pd2(dpip)( -OH)(CFsCOO)2]+[(CFsCOOfH (5).

[0080] Complex 5 was synthesized by combining dpip with two equivalents of Pd(OAc)2 in a methanol / trifluoroacetic acid solution at room temperature for 2 hours (FIG. 3. Scheme 2). Filtration of the reaction mixture followed by the removal of volatiles from the filtrate results in orange solid 5 in good yield (79%). Complex 5 has moderate solubility in most polar organic solvents such as dimethyl sulfoxide, methanol, acetonitrile. TheXH NMR spectrum reveals the most downfield aromatic protons to be a doublet at 6 = 9.37 ppm and a singlet at 6 = 8.84 ppm, likely the imidazopyrimidine protons that are adjacent to the nitrogen. The peak for the remaining imidazopyrimidine proton appears to be present in the multiplet at 6 = 8.18-8.05 ppm. The protons from one pyridyl ring are significantly more downfield than the other (6 = 8.45-8.05 vs 7.62-7.36 ppm), indicating different electronic environments for each pyridyl ring. A peak for the bridging hydroxide is present as a singlet at 6 = 3.07 ppm. Interestingly, a broad singlet is present at 6 = 11.19 ppm, corresponding to a proton present in the counterion of 5 assigned as [(CFsCOO)?!!]'. The19F NMR supports this assignment as three peaks are present (8 = -74.57, -74.96, -76.62 ppm) with a 3 :3 :6 ratio. Therefore, the peaks at 6 = -74.57 and -74.96 ppm correspond to trifluoroacetates on the palladium atoms, and the peak at 6 = -76.62 ppm corresponds to the two equivalent CF3- groups in the counterion. The13C NMR spectrum contains peaks between 6 = 163.39-110.36 ppm corresponding to the aromatic carbons, while the peaks for carbons in CF3COO- groups could not be assigned due to low resolution from13C-19F splitting. The ESI-HRMS spectrum of 5 in acetonitrile contains a peak at m / z = 727.8837 corresponding to the cationic portion of 5 with aformula of [Pd2(dpip)(p-OH)(CF3COO)2]+. Furthermore, the simulated isotopic distribution for this peak was also in good agreement with the above peak.

[0081] Single-crystal X-ray diffraction was performed on 5, with the corresponding structure depicted in FIG. 4 and selected bond lengths and bond angles displayed in Table 1. Pd(l) and Pd(2) are coplanar with dpip, having bite angles of 81.15(18)° for N(l)-Pd(l)-N(2) and 80.70(19)° for N(3)-Pd(2)-N(4). Pd(l) and Pd(2) are square planar, with Pd(l) surrounded by N(l) and N(2) from dpip, 0(1) from the bridging hydroxide, and O(1A) from a molecule of trifluoroacetate. Similarly, Pd(2) is surrounded by N(2) and N(3) from dpip, 0(1) from the bridging hydroxide, and O(1B) from another molecule of trifluoroacetate. The Pd-N and Pd-0 bond lengths are similar, within the range of 1.970(4)-2.023(4) A. Notably, complex 5 is packed as stacked dimers as seen in FIG. 4, giving a Pd(l)-Pd(2)#l bond distance of 3.2448(7) A. The crystal structure also confirms the counterion assignment, with two molecules of trifluoroacetate not closely coordinated to the palladium centers and H(1D) on O(1D) hydrogen bonding to O(1C). The distance between Pd(l) and Pd(2) is 3.6121(7) A, which is greater than the dipalladium distance in [Pd2(bpnp)(p- OH)(DMF)2]3+[3BF4]3' [3.1696(7) A]2and shorter than in an anthyridine-based dipalladium complex [5.2098(4) A],Table 1. Selected bond lengths (A) and bond angles (°) for 5.Pd(l) N(l) 2.012(4) N(l)-Pd(l)-N(2) 81.15(18)Pd(l) N(2) 1.994(5) N(l)-Pd(l)-O(1A) 91.15(18)Pd(l)-O(l) 1.971(4) N(2)-Pd(l)-O(l) 94.74(17)Pd(l)-O(1A) 2.023(4) O(1A)-Pd(l)-O(l) 92.93(16)Pd(2) N(3) 2.001(4) N(3)-Pd(2)-N(4) 80.70(19)Pd(2) N(4) 1.997(5) N(4)-Pd(2)-O(1B) 96.48(18)Pd(2)-O(l) 1.970(4) N(3)-Pd(2)-O(l) 96.81(17)Pd(2)-O(1B) 2.011(4) O(1B)-Pd(2)-O(l) 86.17(16)

[0082] Synthesis and Characterization of [ {Ni2(dpip)(p-Cl)Ch(MeOH)3}2]2+[2Cl]2~ (6)

[0083] The synthesis of complex 6 was achieved by refluxing dpip with 2 equivalents of NiCh 2H2O in methanol for 2 hours (FIG. 3. Scheme 2). Slow addition of diethyl ether to the clear solution resulted in the formation of precipitate which was filtered and washed with acetonitrile to afford yellow solid 6 in good yield (81%). Complex 6 has good solubility in methanol and dimethyl sulfoxide. The paramagneticXH NMR of 6 reveals eleven peaks present between 6 = 174.82-16.79 ppm. The most downfield peaks at 6 = 174.82 and 157.02 ppm are broadened and likely correspondto the proton on each pyridyl proton that is closest in distance to the respective nickel centers. Equally, the most upfield peak is present at 6 = 16.79 ppm, formed by two overlapping peaks, and corresponds to each pyridyl proton that is farthest in distance from the nickel centers. The remaining peaks are present between 6 = 64.32-42.75 ppm. ESI-HRMS data of 6 in methanol revealed a peak at m / z = 493.8793.

[0084] The structure of 6 was determined by single-crystal X-ray diffraction analysis as seen in FIG. 5, which revealed two dinickel complexes dimerized by bridging chlorine atoms [Cl(3) and Cl(3)#l], The nickel atoms are coplanar with dpip, containing bite angles of 80.01(16)° for N(l)-Ni(l)-N(2) and 79.48(14)° for N(3)-Ni(2)-N(4) (Table 2). The coordination environment for Ni(l) and Ni(2) is six-coordinate with a distorted octahedral geometry. The equatorial plane of Ni(l) consists of N(l) and N(2) from dpip, the terminal chloride Cl(l), and the bridging chloride Cl(2), while O(1A) and O(1B) from two molecules of methanol coordinate to the apical sites. Similarly, the equatorial plane of Ni(2) consists of N(3) and N(4) from dpip, the bridging chloride Cl(2), and Cl(3). O(3C) from a molecule of methanol coordinates to one of the apical sites, with the remaining site occupied by a bridging chloride [Cl(3)#l] from the second dinickel complex. The bond lengths for Ni-N and Ni-0 are similar, within the range of 2.082(4)-2.154(3) A, while the Ni-Cl bonds are longer, in the range of 2.3473(16)-2.4632(17) A. The overall complex is a dication, with chloride counterions [Cl(4) and Cl(4)#l] coordinated closely to each dinickel complex. The distance between Ni(l) and Ni(2) is 4.106(2) A while the distance between Ni(2)Table 2. Selected bond lengths (A) and bond angles (°) for 6.Ni(l)-N(l) 2.086(4) N(l)-Ni(l)-N(2) 80.01(16)Ni(l)-N(2) 2.150(4) N(l)-Ni(l)-Cl(l) 93.79(13)Ni(l)-Cl(l) 2.3841(18) N(2)-Ni(l)-Cl(2) 94.24(11)Ni(l)-Cl(2) 2.3543(15) Cl(l)-Ni(l)-Cl(2) 92.01(6)Ni(l)-O(1A) 2.098(4) O(1B)-Ni(l)-O(1A) 174.72(15)Ni(l)-O(1B) 2.106(4) Cl(l)-Ni(l)-O(1A) 86.26(12)Ni(2)-N(3) 2.154(3) N(3)-Ni(2)-N(4) 79.48(14)Ni(2)-N(4) 2.082(4) N(3)-Ni(2)-Cl(2) 97.60(11)Ni(2)-Cl(2) 2.3473(16) N(4)-Ni(2)-Cl(3) 93.52(11)Ni(2)-Cl(3) 2.4632(17) Cl(2)-Ni(2)-Cl(3) 89.50(5)Ni(2)-Cl(3)#l 2.4632(17) O(3C)-Ni(2)-Cl(3)#l 177.64(11)Ni(2)-O(3C) 2.112(4) Cl(3)-Ni(2)-Cl(3)#l 85.61(5)and Ni(2)#l is closer at 3.613(1) A. The distance between Ni(l) and Ni(2) is longer than in 1,8- naphthyridine-based dinickel complexes such as in a pyrazolyl substituted 1,8-naphthyridine complex [3.240(1) A]24and in [Ni2(DPFN)(p-Cl)2Cl(MeOH)]+Cl‘ [3.2218(8) A], Conversely, the distance is shorter than in an anthyridine-based dinickel complex [5.4087(7) A],

[0085] In summary, a novel binucleating ligand based on the imidazopyrimidine motif was developed (dpip) and successfully synthesized on a multi -gram scale in 4 steps in an overall 54% yield. A series of bimetallic complexes were synthesized including the dicopper complex 4, the dipalladium complex 5, and the dinickel complex 6 that were characterized using a combination of NMR, ESI-HRMS, and x-ray crystallography. X-ray crystallography revealed a greater metalmetal distance in comparison to similar 1,8-naphthyridine-based bimetallic complexes.

[0086] EXAMPLES

[0087] The following example embodiments illustrate embodiment ligands in conformance with the above articulated principles and should not be construed as all-encompassing.

[0088] Example 1. Presented in FIG. 6 is an example embodiment of a ligand in conformance with the above articulated principles. M1 / M2 = any combination of transition metals such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Dd, Sg, Bh, Hs.

[0089] (L)n= any number and variation of small molecule ligands, neutral or ionic required to complete outer valency of metal such as halide, CO, perchlorate, sulphate, carbonate, H2O, MeOH, MeCN, carboxylates such as trifluoroacetate, acetate, etc. (L)nmay also be a second or third equivalent of the disclosed ligand with associated R1-R5 groups.

[0090] R3 / R4 / R5 / R = any combination of R1 / R2 and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroaryl alkyl, cycloalkyl, acyl, etc.

[0091] R1 / R2 = any combination of R such as those listed above but especially (although not limited exclusively to) those shown in FIG. 7A and FIG. 7B as exemplified by Compounds (I) through (XXXII).

[0092] Example 2. Presented in FIG. 8 are three (3) embodiments, compounds (A), (B), and (C), of ligands in conformance with the above articulated principles. M1 / M2 / M3 = any combination of transition metals such as Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Rf, Dd, Sg, Bh, Hs.

[0093] X = a g3-bridging ligand such as, but not limited to, OH, O, halide, S, SH, etc.

[0094] (L)n= any number and variation of small molecule ligands, neutral or ionic required to complete outer valency of metal such as halide, CO, perchlorate, sulphate, carbonate, H2O, MeOH, MeCN, carboxylates such as trifluoroacetate, acetate, etc. May also be a second or third equivalent of the disclosed ligand with associated Ri-Rs groups.

[0095] Rs-Rs / R = any combination of R1 / R2 such as those listed above but especially (although not limited exclusively to) those shown in FIG. 7A and FIG. 7B as exemplified by Compounds (I) through (XXXII).

[0096] Example 3. Presented in FIG. 9 is a schematic overview for a generalized method of synthesizing embodiments according to the disclosure. In a first step 900 an -imadazopyrimidine containing ligand, metal salt(s) and one or more optional small molecule ligands are combined into a first mixture. According to step 901 the components of the first mixture are dissolved in a solvent forming a second mixture, the second mixture is brought to one or more chosen reaction temperatures and stirred until complete and there is formed a crude metallic complex 902. As seen in 903 the crude metallic complex is “worked up” (e.g., filtered, washed with solvent, dried, other purification and cleaning steps as necessary, etc.) leaving a purified metallic complex 904. Each embodiment of the method may require one or more different solvents, cosolvents, reaction temperatures, reagents, and other parameters such as those skilled in are would commonly recognize to account for in view of the herein provided examples.

[0097] MATERIALS AND METHODS

[0098] General Information

[0099] Reactions were performed under an argon atmosphere using oven dried glassware unless specified. Ethanol and methanol were treated with activated 3 A molecular sieves for 72 hours, otherwise reaction solvents were analytical grade and used without purification. Chemical reagents were purchased from Sigma-Aldrich or Oakwood Chemical and used without further purification.1H NMR and19F NMR spectra were recorded on a Briiker AVANCE300 (300 MHz and 283 MHz respectively) 8 NMR spectrometer.13C NMR spectra were broadband proton decoupled and recorded on a Briiker AVANCE300 (75 MHz) 6 NMR spectrometer. Chemical shifts are reported in parts per million (ppm) relative to either chloroform (6 = 7.26), acetonitrile (6 = 6 1.94), or methanol (6 = 3.31) for 'H NMR and relative to chloroform (6 77.16) or acetonitrile (6 =1.32) for13C NMR. The paramagnetic1H NMR spectra of 4 and 6 were recorded at 298.1 K with a spectral width of -20 to 200 ppm, using a relaxation delay of 2s and averaging 64 scans. High resolution mass spectra were obtained via electrospray ionization which was measured on a Thermo Scientific Q Exactive Plus Hybrid Quadrupole-Orbitrap at the University of Waterloo Mass Spectrometry Facility. X-ray crystal structures were determined by Dr. Jalil Assoud at the University of Waterloo and figures of X-ray crystal structures were generated using Mercury.

[0100] Synthesis of 3-Dimethylamino-l-pyridin-2-yl-propenone 1

[0101] Prepared according to a previously reported procedure with modification. 2-Acetyl pyridine (2.8 mL, 25.0 mmol) and N,N-dimethylformamide dimethyl acetal (6.7 mL, 50.4 mmol) were combined in a round bottom flask equip with a reflux condenser and stir bar. The mixture was stirred at reflux for 7 hours. After removal of volatiles in vacuo, the crude solid was recrystallized using a 2: 1 hexanes:ethyl acetate solvent mixture. The crystals were collected by vacuum filtration to afford yellow solid 1 (3.4861g, 80%). 'HNMR (300 MHz, CDCh) 8 8.60 (d, = 4.4 Hz, 1H), 8.12 (d, = 7.9 Hz, 1H), 7.88 (d, J= 12.7 Hz, 1H), 7.77 (td, J= 7.7, 1.4 Hz, 1H), 7.33 (dd, J= 6.8, 5.2 Hz, 1H), 6.42 (d, J= 12.6 Hz, 1H), 3.14 (s, 3H), 2.96 (s, 3H).13C NMR (75 MHz, CDCh) 6 186.6, 156.0, 154.5, 148.1, 136.6, 125.2, 121.8, 91.0, 45.0, 37.3. ESI-HRMS: m / z [M + H]+calcd for C10H13N2O, 177.1022; found, 177.1026.

[0102] Synthesis of 2-Amino-4-( 2-pyridinyl) -pyrimidine 2

[0103] Prepared according to a previously reported procedure with modification. Compound 1 (3.2803 g, 18.7 mmol), guanidinium chloride (1.7883 g, 18.7 mmol), sodium hydroxide (0.7487 g, 18.7 mmol), and 1-butanol (90 mL) were combined in a round bottom flask equipped with a reflux condenser and stir bar. The solution was stirred at reflux for 18 hours. After cooling the reaction to room temperature, the white precipitate was filtered and washed with 1-butanol. The yellow filtrate was dried in vacuo and the crude solid was recrystallized using 1-butanol. Crystals were collected by vacuum filtration to afford white solid 2 (2.9137 g, 90%). 'H NMR (300 MHz, CDCh) 6 8.68 (d, J= 4.6 Hz, 1H), 8.42 (d, J= 5.2 Hz, 1H), 8.30 (d, J= 7.9 Hz, 1H), 7.79 (td, J = 7.8, 1.7 Hz, 1H), 7.62 (d, J= 5.2 Hz, 1H), 7.34 (dd, J= 7.4, 4.8 Hz, 1H), 5.41 (s, 2H).13C NMR (75 MHz, CDCh) 6 164.2, 163.3, 159.3, 154.4, 149.5, 137.0, 125.1, 121.5, 108.0. ESI-HRMS: m / z [M + H]+calcd for C9H9N4, 173.0822; found, 173.0826.

[0104] Synthesis of 2-(Bromoacetyl)pyridine 3

[0105] Prepared according to a previously reported procedure with modification. The reaction was performed open to air. In a three-necked round bottom flask equip with a septum, a reflux condenser, and an overhead stirrer fitted with a glass stirring rod, was combined 2-acetylpyridine (2.25 mL, 20.1 mmol) and a 33wt% hydrobromic acid solution in acetic acid (25 mL) at 0 °C. To this solution was added Br2(1.03 mL, 20.1 mmol) dropwise over 2 hours, maintaining the temperature at 0 °C with vigorous stirring. After the addition, the septum was replaced with a glass stopper and the mixture was stirred at 40 °C for 1 hour, then stirred at 75 °C for 1 hour. After cooling the reaction to room temperature, diethyl ether (200 mL) was added to the mixture, forming precipitate that was then filtered (the filtrate was quenched with a saturated sodium thiosulfate and sodium bicarbonate solution). The precipitate was added to a saturated solution of sodium bicarbonate and extracted 3 times with dichloromethane. The extractions were combined, dried over anhydrous magnesium sulfate, filtered, and the volatiles were removed in vacuo. The residue was purified by silica gel column chromatography (2: 1 dichloromethane:hexanes) to afford yellow liquid 3 (3.6114 g, 90%). The compound was used immediately for the next step. ’H NMR (300 MHz, CDC13) 8 8.68 (d, J= 4.7 Hz, 1H), 8.09 (d, J= 7.8 Hz, 1H), 7.86 (td, J= 7.7, 1.6 Hz, 1H), 7.55 - 7.48 (m, 1H), 4.85 (s, 2H).13C NMR (75 MHz, CDCI3) 6 192.6, 151.5, 149.3, 137.3, 127.9, 122.8, 32.6. ESLHRMS: m / z [M + H]+calcd for C7H7BrNO, 199.9706; found, 199.9709.

[0106] Synthesis of 2, 7-Di(pyridin-2-yl)imidazo[ 1, 2-a]pyrimidine (dpip)

[0107] 2 (3.2872 g, 19.1 mmol), 3 (3.8187 g, 19.1 mmol), and ethanol (40 mL, 0.5 M) were combined in a round bottom flask equip with a reflux condenser and stir bar. The reaction mixture was stirred at reflux for 18 hours. Over the course of the reaction, all solids dissolved, then bright yellow precipitate formed over time. After cooling the reaction to room temperature, the yellow precipitate was filtered and washed with additional ethanol. The precipitate was then dissolved in minimal water and to the solution was slowly added an aqueous solution of sodium hydroxide (0.25 M, 80 mL). The resulting precipitate was filtered and rinsed with water then methanol to afford light yellow dpip (4.3410 g, 83%). 'H NMR (300 MHz, CDCI3) 6 8.76 - 8.67 (m, 2H), 8.63 (ddd, J = 4.8, 1.8, 0.9 Hz, 1H), 8.54 (d, J = 7.1 Hz, 1H), 8.40 (dt, J = 7.9, 1.0 Hz, 1H), 8.28 (s, 1H), 8.17 (d, J= 7.1 Hz, 1H), 7.91 - 7.79 (m, 2H), 7.39 (ddd, J= 7.5, 4.8, 1.2 Hz, 1H), 7.30 - 7.26 (m, 1H). Compound is too insoluble to record a13C NMR spectrum. ESI-HRMS: m / z [M + H]+calcd for CI6HI2N5, 274.1082; found 274.1084.

[0108] Synthesis of Cu2(dpip)( -OH)(CFsCOO)3 4

[0109] dpip (0.1367 g, 0.50 mmol) and Cu(0Ac)2 H20 (0.1997 g, 1.00 mmol) were combined in a round bottom flask equip with a stir bar. To the flask was added MeOH (5 mL), then trifluoroacetic acid (2.5 mL). The mixture was stirred at room temperature for 2 hours. Within 5 minutes, all solids dissolved then formation of green precipitate over time occurred. The mixture was filtered and the solid was washed with a 2: 1 diethyl etheracetonitrile mixture (20 mL) then dried in vacuo to afford green solid 4 (0.3498 g, 92%).!H NMR (300 MHz, CD3OD) 6 69.65 (br, 1H), 63.84 (1H), 33.03 (1H), 29.70 (1H), 29.13 (1H), 26.34 (1H), 22.57 (1H), 21.72 (1H), 19.86 (1H), 9.76 (1H), 9.50 (1H). ESLHRMS: m / z [M - CF3COO]+calcd for C20H12O5N5CU2F6, 641.9329; found, 641.9330.

[0110] Synthesis of [Pd2(dpip)(p-OH)(CF3COO)2]+[(CFsCOO)^]' 5

[0111] dpip (0.1367 g, 0.50 mmol) and Pd(OAc)2 (0.2245 g, 1.00 mmol) were combined in a round bottom flask equip with a stir bar. To the flask was added MeOH (10 mL), then trifluoroacetic acid (2.5 mL). The red-brown mixture was stirred at room temperature for 2 hours. The mixture was filtered and the volatiles were removed from the filtrate in vacuo to afford orange solid 5 (0.3771 g, 79%). Single crystals suitable for X-ray diffraction were obtained by vapor diffusion of ethyl acetate into a saturated 9: 1 acetonitrile :trifluoroacetic acid solution at room temperature. 'H NMR (300 MHz, CD3CN) 6 11.19 (br s, 1H), 9.37 (d, J = 7.1 Hz, 1H), 8.84 (s, 1H), 8.45 (d, J= 7.6 Hz, 1H), 8.33 (td, J= 7.8, 1.2 Hz, 1H), 8.18 - 8.05 (m, 3H), 7.62 (t, J= 6.6 Hz, 1H), 7.51 (d, J= 5.5 Hz, 1H), 7.44 - 7.36 (m, 2H), 3.07 (s, 1H).19F NMR (283 MHz, CD3CN) 6 -74.57 (s), -74.96 (s), -76.62 (s).13C NMR (75 MHz, CD3CN) 6 163.4, 154.7, 151.2, 149.9, 148.4, 145.8, 144.4, 143.9, 143.1, 138.4, 132.0, 129.5, 128.5, 124.7, 116.7, 110.4. Carbon signals from CF3COO- groups are not resolved due to13C-19F splitting. ESI-HRMS: m / z [M - 2CF3COO - H]+calcd for C2oHi205N5F6Pd2, 727.8807; found, 727.8837.

[0112] Synthesis of [{Ni2(dpip)(p-Cl)Ch(MeOH) s}2]2+[2Cl]2~ 6

[0113] dpip (0.1367 g, 0.50 mmol) and NiCh 2H2O (0.2377 g, 1.00 mmol) were combined in a round bottom flask equip with a stir bar. To the flask was added methanol (10 mL), then the reaction was stirred at reflux for 2 hours. Over the course of the reaction all solids dissolved. After cooling to room temperature, diethyl ether (40 mL) was added slowly resulting in the formation of yellow precipitate. The precipitate was filtered, washed with acetonitrile (50 mL), then dried in vacuo to afford yellow solid 6 (0.2555 g, 81%). Single crystals suitable for X-ray diffraction were obtained by slow evaporation from a benzene / methanol solution.1H NMR (300 MHz, CD3OD) 6174.82 (br, 2H), 157.02 (br, 2H), 64.32 (2H), 49.03 (2H), 47.73 (4H), 45.92 (2H), 45.24 (2H), 42.75 (2H), 16.79 (4H). ESI-HRMS: m / z [1 / 2M - Cl - 3MeOH]+calcd for CieHnNsChNi^ 493.8782; found, 493.8793.

[0114] Synthesis of Pd(dpip)(O2CCFs)2

[0115] FIG. 10 presents Scheme 3, a means of synthesis of Pd(dpip)(C>2CCF3)2. dpip (0.0683 g, 0.25 mmol), Pd(O2CCFs)2 (0.0831 g, 0.50 mmol), and acetonitrile (10 mL, 0.025 M) were stirred at room temperature for 2 hours in a round bottom flask. Upon stirring, all solids dissolved then the formation of beige precipitate occurred over time. The mixture was filtered then the solid was washed with acetonitrile (20 mL) and dried in vacuo to afford the product (0.1259 g, 83%).XH NMR (300 MHz, CD3OD) 8 9.75 (d, J= 7.0 Hz, 1H), 9.46 (d, J= 5.6 Hz, 1H), 9.16 (d, J= 7.0 Hz, 1H), 8.70 (s, 1H), 8.40 - 8.21 (m, 4H), 7.96 (dt, J= 7.7, 1.6 Hz, 1H), 7.78 (dt, J= 7.4, 1.6 Hz, 1H), 7.27 (d, J= 7.9 Hz, 1H). ESI-HRMS: m / z [M - CF3COO]+calcd for CisHuChNsFsPd, 491.9894; found, 491.9917.

[0116] Synthesis of Ni3(dpip)(p-OH)(O2CCF3)5(CHsCN)(H2O)

[0117] FIG. 11 presents Scheme 4, a means of synthesis of Ni3(dpip)(p- OH)(O2CCF3)5(CH3CN)(H2O). dpip (0.1367 g, 0.50 mmol), Ni(O2CCF3)2 4H2O (0.5352 g, 1.50 mmol), and acetonitrile (20 mL, 0.025 M) were stirred at room temperature for 2 hours in a round bottom flask. Upon stirring, all solids dissolved and the solution turned light green. Vapour diffusion of chloroform into the reaction mixture afforded light green crystals of the product (0.4496 g, 82%). 'H NMR (300 MHz, CD3CN) 6 146.71 (br, 1H), 135.76 (br, 1H), 55.61 (1H), 50.79 (1H), 50.37 (1H), 45.03 (1H), 41.59 (1H), 40.59 (1H), 40.06 (1H), (14.58, 2H). ESI-HRMS: m / z [M - CF3COO - MeCN - H2O]+calcd for C24Hi2O9N5Fi2Ni3, 915.8498; found, 915.8514.

[0118] Synthesis of Co3(dpip)(p-OH)(O2CCF3)5(CHsCN)2

[0119] FIG. 12 presents Scheme 5, a means of synthesis of Co3(dpip)(p- OH)(O2CCF3)5(CH3CN)2. dpip (0.0683 g, 0.25 mmol), Co(OAc)24H2O (0.1868 g, 0.75 mmol), acetonitrile (4 mL), and trifluoroacetic acid (1 mL) were stirred at room temperature for 2 hours in a round bottom flask. Upon stirring, all solids dissolved and the solution turned orange. The volatiles were removed in vacuo, then the crude solid was redissolved in acetonitrile (12 mL). Vapor diffusion of chloroform into the acetonitrile mixture afforded orange crystals of the product (0.2411 g, 87%). 'H NMR (300 MHz, CD3CN) 6 95.09 (1H), 75.47 (br, 1H), 63.70 (1H), 52.65 1(br, 3H), 34.68 (1H), 30.03 (1H), 27.72 (1H). ESI-HRMS: m / z [M - CF3COO - 2MeCN]+calcd for C24H12O9N5F12CO3, 918.8434; found, 918.8439.

[0120] Synthesis of [Cu2Ni2(dpip)2(p-OH)2(O2CCFs)5(H2O)2] [(O2CCF3)]

[0121] FIG. 13 presents Scheme 6, a means of synthesis of [Cu2Ni2(dpip)2(p- OH)2(O2CCF3)5(H2O)2][(O2CCF3)]. dpip (0.0683 g, 0.25 mmol), Ni(O2CCF3)24H2O (0.0892 g, 0.25 mmol), Cu(O2CCF3)2H2O (0.0769 g, 0.25 mmol) and acetonitrile (10 mL, 0.025 M) were stirred at room temperature for 2 hours in a round bottom flask. Upon stirring, all solids dissolved and the solution turned green. Vapour diffusion of chloroform into the reaction mixture afforded green crystals of the product (0.1713 g, 89%). 'H NMR (300 MHz, CD3CN) 8 136.82 (br, 1H), 77.50 (1H), 54.71 (1H), 49.74 (1H), 40.18 (1H), 37.07 (1H), 31.88 (1H), 31.16 (1H), 24.80 (1H), 14.03 (1H), 11.29 (1H). ESI-HRMS: m / z [M - CF3COO - 2H2O]+calcd for C42H240i2NioCu2Fi5Ni2, 1386.8629; found, 1386.8632.

[0122] Synthesis of CuNi2(dpip)(p-OH)(O2CCFs) 5(H2O)

[0123] FIG. 14 presents Scheme 7, a means of synthesis of CuNi2(dpip)(p- OH)(O2CCF3)5(H2O). dpip (0.0683 g, 0.25 mmol), Ni(O2CCF3)24H2O (0.1784 g, 0.50 mmol), Cu(O2CCF3)2 H2O (0.0769 g, 0.25 mmol) and acetonitrile (20 mL, 0.013 M) were stirred at room temperature for 2 hours in a round bottom flask. Upon stirring, all solids dissolved, and the solution turned green. Vapor diffusion of chloroform into the reaction mixture afforded green crystals of the product (0.2491 g, 95%). 'H NMR (300 MHz, CD3CN) 6 145.16 (br, 1H), 121.87 (br, 1H), 56.05 (1H), 48.88 (1H), 45.56 (1H), 42.07 (1H), 38.45 (1H), 36.94 (1H), 36.06 (1H), 14.22 (1H), 12.27 (1H). ESI-HRMS: m / z [M - CF3COO - H2O]+calcd for C24Hi2O9N5CuFi2Ni2, 920.8441; found, 920.8443.

[0124] X-ray Crystallography

[0125] The single-crystal X-ray diffraction studies were performed using a Bruker Kappa Apex II CCD equipped with Mo-Ka radiation at room and low temperature. Several orange plate like (5) and yellow block like (6) single crystals were tested for the quality and unit cell determination, with most of them twinned due to the stacking of the plates on the top of each other. The best crystals were chosen for data collection at room temperature and at low temperature to reduce the thermal vibration of the counter-anions and for better data accuracy. The APEX II suite was used to determine the best strategy for full data coverage, by scanning co- and <|) in different sets of frames. The exposure time was between 20 and 40 seconds per frame depending on the sizeand the scattering of the crystals. The data were corrected for Lorentz and polarization effects, and a multi-scan absorption correction was applied using the SADABS part of the APEX II software.31The structure solutions were obtained by direct method and refined using the least-square method incorporated into the SHELXTL package. All the non-hydrogen atoms were refined anisotropically, and all the hydrogen atoms were refined in the idealized geometrically positions using a rigid model with C-H = 0.93 A and isotropic displacement parameters UiS0(H) = 1.2Ueq (C). The structure refinement for 5 and 6 reached reasonable R-values, despite a small rest electron density of 1.98eA'3, due the counter-anion disorder for 5 and 1.244 eA'3due to the twining for 6. For 6, a hydrogen atom was not assigned for O(1B) (methanol) because of issues with reliable placement, but the hydrogen atom was still included in the formula.

[0126] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the various embodiments in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment as contemplated herein without any additional undue experimentation. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the various embodiments as set forth in the appended claims. In particular, a vast number of additional R groups other than the exemplary ones disclosed are expressly contemplated as compatible with one or more embodiments of the disclosure.

[0127] Since certain changes may be made in the above-described disclosure, without departing from the spirit and scope of the disclosure herein involved, it is intended that all of the subject matter of the above description shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.

[0128] Finally, the written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of theclaims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

CLAIMSWhat is claimed is:

1. A composition, comprising: an imidazopyrimidine-based ligand coupled to a metal atom to form a metallic complex or catalyst.

2. The composition of claim 1 wherein the imidazopyrimidine-based ligand is 2,7-di(pyridin-2- yl)imidazo[ 1 ,2-a]pyrimidine (dpip).

3. The composition of claim 1, wherein the imidazopyrimidine-based ligand is:wherein, Mi and M2 is a transition metal independently selected from the group of transition metals of the periodic table; wherein R is any one or more of: compounds (I) though (XXXII) and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, cycloalkyl, and acyl; wherein, L is a small molecule ligand; and, wherein, n is an integer based on the number required to complete the outer valency of the metal.

4. The composition of claim 1, wherein the imidazopyrimidine-based ligand is selected from the group consisting of (A), (B), and (C) below:(A), (B), and (C). wherein Mi, M2, and M3 are transition metals independently selected from the group of transition metals of the periodic table; wherein R is any one or more of: compounds (I) though (XXXII) and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, cycloalkyl, and acyl; wherein, L is a small molecule ligand; wherein, n is an integer based on the number required to complete the outer valency of the metal; and,X is a g3-bridging ligand.

5. The composition of claim 1 wherein the imidazopyrimidine-based ligand is 2,7-di(pyridin- 2-yl)imidazo[ 1 ,2-a]pyrimidine (dpip).

6. The composition of claim 5 wherein the dpip is synthesized according to the process of scheme 1.

7. The composition according to claim 1 wherein the imidazopyrimidine-based ligand is synthesized into a multi-metallic complex.

8. The composition according to claim 7 wherein the multi-metallic complex is synthesized according to scheme 2.

9. The composition according to claim 3 or claim 4 wherein L is selected from the group: halide, CO, perchlorate, sulphate, carbonate, H2O, MeOH, MeCN, carboxylates such as trifluoroacetate, acetate, and the like; and n is 0-3.

10. The composition according to claim 9 wherein (L)nis a second or third equivalent of the ligand of any of claims 1-3.

11. The composition according to claim 2 wherein R3 / R4 / R5 / R is any combination of R1 / R2 and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroarylalkyl, cycloalkyl, acyl, and the like.

12. The composition according to claim 2 or claim 3 wherein R1 / R2 is any compound from claim 10.

13. The composition according to claim 3 or claim 4 wherein R1 / R2 is any combination of R as exemplified by compounds (I) though (XXXI I) and hydrogen, halogen, hydroxyl, cyano, nitro, amino, alkylamino, dialkylamino, carboxyl, alkyl, alkenyl, alkynyl, aryl, arylalkyl, heteroaryl, heteroaryl alkyl, cycloalkyl, acyl, and the like.

14. The composition according to claim 4 wherein X is a ps-bridging ligand selected from the group comprising: OH, O, halide, S, SH, and the like.

15. A method, of producing a composition according to any of the above claims, comprising: providing an imadazopyrimidine containing ligand, one or more metal salts, and one or more optional small molecule ligands; combining the imadazopyrimidine containing ligand, one or more metal salts, and one or more optional small molecule ligands to form a first mixture; dissolving the first mixture in a solvent, forming a second mixture; bringing the second mixture to at least a first temperature while stirring, forming a crude metallic complex; and, working up the crude metallic complex to provide a purified metallic complex.

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