Zirconocene dimer catalyst complex, method for obtaining same and use for ethylene polymerisation

Abstract

The invention relates to zirconocene dimer catalyst complex of formula (2); a method for obtaining same, including reaction intermediates; and the use thereof as an ethylene polymerisation catalyst.

Description

[0001] Zirconocene dimer catalyst complex, its production process and use for the polymerization of ethylene

[0002] DESCRIPTIVE MEMORANDUM

[0003] BACKGROUND OF THE INVENTION

[0004] The exploration of early transition metal chemistry has focused primarily on complexes containing additional cyclopentadienyl ligands. Mono- and dicyclopentadienyl compounds of titanium, zirconium, and hafnium have demonstrated their usefulness as organometallic materials, generating significant interest in Group 4 metallocenes.

[0005] The reduction of zirconocene dichloride has long been a captivating topic that has attracted the interest of chemists. This fascination has been fueled by several promising characteristics exhibited by low-valence zirconium(II,III) organometallic compounds, such as dinitrogen fixation, hydride formation, reactivity with alkynes, and the possibility of MM bonding.

[0006] The rotational independence of the two rings along the CC bond within the dinuclear complex imparts steric adaptability. This flexibility allows for a wide range of metal-metal interactions, providing a useful template for evaluating cooperative effects through direct or ligand-mediated communication, leading to the design of active multimetal structures.

[0007] Despite the moderating influence of electronic conjugation on unrestricted rotation, well-established complexes predominantly exhibit two main rotameric configurations (cis and trans) of the metal centers with respect to the planar fulvalene, a feature consistently observed in solid-state structures.

[0008] Despite numerous recent investigations, the chemistry of low-valence zirconium remains comparatively underexplored compared to titanium chemistry. While the organometallic chemistry of trivalent titanium boasts considerable breadth, with numerous dimeric titanium derivatives incorporating the q ligand 5 -r| 5The parallel chemistry of zirconium(III) and fulvalene is notably scarce. In particular, the postulation of a fulvalene ligand in zirconium(III) chemistry has only occurred in a few examples in the literature. On the other hand, dinuclear organometallic complexes incorporating the fulvalene ligand have recently attracted renewed attention, emerging as a topic of renewed interest. The fulvalene ligand, known for its flexibility, is capable of accommodating structures with metal-metal bonds, additional bridging ligands, and open trans geometries. This versatility provides these complexes with a spectrum of metal-metal distances and varying degrees of electronic communication between the metals. These intricate complexes have been extensively studied as models for the interaction of organic fragments with metal surfaces and as potential catalysts for synthetic organic transformations.

[0009] Furthermore, fulvalene complexes present an opportunity to juxtapose the properties of comparable mono- and binuclear complexes, with the aim of testing the hypothesis that the cooperative interaction of two metal centers with a substrate can lead to transformations that are unattainable when only one metal is present.

[0010] Regarding zirconium complexes derived from the fulvalene ligand and unsubstituted as-indacene, the prospect is remarkably intriguing, as it allows the formation of dinuclear complexes characterized by a short intermetallic distance and, moreover, can even facilitate subtle metal-metal interactions, as observed in specific compounds. The unrestricted rotation of the rings around the C-C bond with respect to the fulvalene plane introduces the possibility of two conformations of the metal fragments, cis and trans, a characteristic primarily influenced by electronic and steric factors. This ligand can be conceptualized as a cyclopentadienyl group substituted by another identical group, as demonstrated in ligands with fulvalene bridges.

[0011] State of the Art

[0012] In order to demonstrate the advantages of the present invention, an analysis of the prior art was carried out, where the most relevant documents are summarized below.

[0013] Patent application CL202203464 provides a complex derived from as-indacene as a catalyst for olefin polymerization, wherein the complex has the formula [Cp*ZrCl2]2-as-lc, Cp*pentamethylcyclopentyl as-indacene is an asymmetric non-alkylated indacene. This complex forms a catalyst system together with a cocatalyst selected from aluminoxane, combinations of aluminoxane with Al-alkyls, boron or borate cocatalysts, and combinations of aluminoxanes with boron-based cocatalysts. The described system enables the preparation of a polyethylene homopolymer, polypropylene, a propylene-ethylene copolymer, or a C4-10 alpha-olefin propylene copolymer. US2021017307 discloses novel metallocene catalysts enabling polymerization, catalyst productivity, and yield in the production of high molecular weight polypropylene homopolymers.The metallocene catalytic complexes in this document are asymmetric, meaning, according to its authors, that the two ligands that form the metallocene are different, since each ligand carries a set of substituents that are chemically different.

[0014] WO9735891 discloses a method for obtaining supported bimetallic ethylene polymerization catalysts with an improved interparticle distribution of Zr active sites, which, according to its authors, facilitates large-scale production of the catalyst. The product obtained by this method is a metallocene complex and a trialkylaluminum compound, wherein the metallocene complex contains one or two substituted or unsubstituted cyclopentadienyl groups and a transition atom selected from the group consisting of titanium, zirconium, and hafnium, wherein the trialkylaluminum compound contains linear or branched alkyl groups, and wherein the product is soluble in paraffinic hydrocarbon solvents.

[0015] The document “A new series of zirconium metallocenes derived from partially alkylated s-indacene with potential applications in the polymerization of ethylene.”, Inorganica Chimica Acta. (2015); 434: 121-126, discloses a study on metallocenes linked to s-indacene that considers only one circometallocene group, while in this proposal there are two, and, in addition, a partially alkylated s-indacene is used as a ligand to that circometallocene.

[0016] US2022363703 discloses novel bisindenyl ligands, their complexes, and catalysts comprising those complexes. The invention also relates to the use of novel bisindenylmetalocene catalysts for the production of polypropylene homopolymers or propylene copolymers, especially with ethylene, exhibiting high activity levels, high molecular weight, and ideal melting points. The catalysts are particularly useful in the manufacture of propylene-ethylene copolymers, as—according to the inventors—they exhibit remarkable catalytic activity in such polymerizations.

[0017] US2021238319 discloses novel transition metal compounds, catalytic systems comprising them, and processes employing them for olefin polymerization. Specifically, D6 relates to a novel substituted tetrahydro-as-indacene complex and a method for producing said substituted or unsubstituted tetrahydro-as-indacene.

[0018] US6232484 discloses bridged zirconocene compounds, the corresponding ligands, a novel process for their preparation, and the use of said zirconocenes as catalytic components in the polymerization of olefins. Of all the documents found, none possesses all the features of the present invention.

[0019] BRIEF DESCRIPTION OF THE FIGURES

[0020] Figure 1. X-ray representation for [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc] (1) at the 50% probability level for thermal ellipsoids

[0021] Figure 2. X-ray representation for [{(q 5 -C5Me5)Zr(p2-Cl)2)3(p 3-O)(p-OH)](2) at the 50% probability level for thermal ellipsoids.

[0022] Figure 3. Structures of the two isomers for (2).

[0023] Figure 4. Electrostatic potential surface for (2), viewed above the Zr3 ring. Isosurface value of 0.001 ua taking into account the van derWaals surface.

[0024] DESCRIPTION OF THE INVENTION

[0025] The invention relates to a catalyst complex and its method of obtaining it, including reaction intermediates.

[0026] Specifically, zirconium dimers and trimers and the respective synthesis of these complexes are described. In particular, the present invention focuses on complexes 1 and 2:

[0027] (1 ) [{(n 5 -C5Me5)Zr(p2-Cl)}2-as-lc]

[0028] (2) [{(q 5 -C5Me5) Zr(p2-Cl)2)}3( M 3-O)(p-OH)],

[0029] derivatives of bimetallic zirconium(IV) precursors as-indacene:

[0030] [{(q 5 -C5Me5) ZrCl2}2-as-lc].

[0031] Furthermore, the invention comprises the synthesis of said compounds, which is represented in Scheme 1 below:

[0032] Scheme I. Synthetic route for complexes (1) and (2).

[0033] Specifically, the synthesis method comprises the following steps: a. Mix as a precursor [{(q 5-C5Me5)ZrCl2}2-as-lc] with a sodium amalgam in toluene, at room temperature, for a period of between 36 and 60 hours; b. Heat the mixture under reflux for a period of 1 to 3 hours; c. Cool to room temperature; d. Filter the solution obtained in the previous step, recovering the residue; e. Wash the residue with toluene until the washing solution becomes colorless, obtaining complex (1); f. Mix complex (1) with a stoichiometric excess of water, stirring it in toluene at a temperature of between 65 and 100 °C for a period of between 25 and 40 hours; g. Filter the mixture obtained in the previous step and proceed to dry it, giving rise to complex (2).

[0034] In one specific embodiment, in step (a) a sodium amalgam between 0.4 and 0.6% is used.

[0035] In step b, the temperature reached is 110°C, the boiling point of toluene. Whereas in step (f) the preferred temperature is 80°C.

[0036] In another realization, a ratio of the precursor is considered [{(q 5 -C5Me5)ZrCl2}2-as-lc] to the sodium amalgam of between 30:1 to 20:1 by weight, preferably 30:1 .

[0037] Toluene is used in a weight:volume ratio of precursor to toluene of between 10:1 and 7:1.

[0038] To continue the reaction and obtain complex (2) a ratio of between 1:1 to 1:2 weight:volume of complex (1) and toluene is considered.

[0039] EXAMPLES

[0040] All reactions were carried out under nitrogen using standard Schlenk techniques, and the NMR (Nuclear Magnetic Resonance) solvents were prepared inside the dry chamber under nitrogen.

[0041] The starting compounds 1,8-dihydro-as-indacene, Cp*ZrCl3y [{(q 5 -C5Me5)ZrCl2}2-as-lc] were synthesized using the methods described above. NMR spectra were recorded on a Bruker ARX400 ( 1H, 400.13 MHz); spectrometers at 298 K. The solvents used were pre-dried and distilled using standard techniques with an appropriate drying agent. Magnetic susceptibility measurements were performed using a vibrating sample magnetometer (VSM). X-ray data were collected on an Enraf ​​Nonius diffractometer at 150 K for the complexes [{(q 5 -C5Me5)Zr(p2-Cl)}2- as-lc] (1) already 100 K for the complexes [{(q 5 -C5Me5)Zr(p2-Cl)2)}3(p 3-O)(p-OH)] (2). All data of the represented structure were collected with monochromatic graphite MoKa radiation (wavelength = 0.71073 Å) using phi and omega scans.

[0042] Computational details

[0043] All Density Functional Theory (DFT) calculations were performed using DFTs at the theoretical level TZ2P / BP86-D3(BJ), within the frozen core (large core) approximation, using the ADF2021 ensemble. Geometry optimizations were performed without any symmetry constraints, using the analytical energy gradient method implemented by Versluis and Ziegler. The Hessian calculation without negative values ​​indicates the true minimal nature of the calculated structures. An energy convergence criterion of 10 was used for the evaluation of the relaxed structures. 4 Hartree, a gradient convergence criterion of 10 3 Hartree / Á and a radial convergence criterion of 10 2 A. The effects of the solvent and the counterion were considered using the conductor-type shielding model (COSMO) with toluene as the solvent.

[0044] Zirconium di-trimer complexes (1), (2)

[0045] Example 1. Synthesis of the complex (1) [{(r] 5 -C5Me5) Zr(p2-Cl)}2-as-lc]

[0046] A mixture of [{(q 5 [C5Me5)ZrCl2}2-as-lc] (250 mg, 0.334 mmol) and 0.5% sodium amalgam Na(Hg) (9.2 mg, 0.400 mmol) were mixed in toluene (30 mL) at room temperature for 48 h. The reaction mixture was then heated under reflux for 2 h. A yellow solution was obtained. After cooling to room temperature, the solution was filtered and the residue was washed with toluene until the wash solution was colorless. All extracts were collected and combined, and the resulting solution was concentrated to 10 mL. Upon cooling to -30 °C, 0.15 g (60.0% yield) of (1) was obtained as yellow crystals.

[0047] Calculated analysis for C 32 H 38 Zr2Cl2 (675.96.): C, 56.88; H, 5.67. Found: C, 57.10; H, 5.80.

[0048] MRI 1H (CeDe, 400 MHz): 5 1 .86 (s, 30H, C{H}3(Cp*)); 4.58 (d, 4H, C{H}) 4.69 (t, 2H, C{H},J= 3.2 Hz); 6, 00 (s, 2H, C{H}).

[0049] Example 2. Synthesis of the complex (2) [{(r] 5 -C5Me5)Zr(p2-Cl)2)}3(p3-O)(p-OH)]

[0050] A mixture of [(ZrCp*(p2-Cl))2-as-lc] (1) 30 mg (3,240 mmol) and a stoichiometric excess of water (9 pL, 0.009 mmol) was stirred in toluene (40 mL) at 80 °C for 32 hours. Subsequently, the mixture was filtered and dried, yielding a residue. Crystallization from dichloromethane produced 0.021 g (70.0% yield) of (2), obtained as yellow crystals.

[0051] Calculated analyses for C 30 H46Zr3Cl6O2 (925.03.): C, 38.92; H, 5.01. Found: C, 39.10; H, 5.15

[0052] MRI 1 H (C6D6, 400 MHz): 5 2.01 (s, 15H, C{H}3(Cp*)); 1 .76 (s, 15H, C{H}3(Cp*)); 1 .55 (s, 15H, C{ / 7}3(Cp*)); OH, 4.39 (d, 1 H). Example 3. Results of the complexes

[0053] (1) [{(n 5 -C5Me5) Zr(p2-Cl)}2-as-lc] and

[0054] (2) [{(n 5 -C5Me5)Zr(p2-Cl)2)}3(p3-O)(p-OH)]

[0055] Complexes (1) and (2), as shown in Scheme I, were derived from the bimetallic zirconium(IV) compound as-indacene using a previously reported route. Complex (1) represents the first undisputed example of a dimeric Zr(III) compound containing an as-indacene ligand, presenting a unique opportunity to develop the chemistry of low-valence zirconium dinuclear complexes. The preparation of complex (1) [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc] involved the reduction of the starting material [{(r| 5[-C5Me5) ZrCl2}2-as-lc] in toluene with sodium amalgam (0.5% Na / Hg) containing exactly 1.2 molar equivalents of sodium. This reaction produced a large amount (60%) of a yellow solid. During the synthesis, the color of the solution changed with exposure to light. Initially, the reaction produced a yellow solution, which turned green / brown and then a light brown, translucent solution with an orange-brown residue. The final product, obtained as yellow crystals, showed a marked color change when placed in an NMR tube under light. After collecting and combining all the extracts, the solution was concentrated to 10 mL. Upon cooling to -30 °C, 0.15 g (60.0% yield) of (1) was obtained as yellow crystals.

[0056] Subsequently, zirconium atoms bonded by chlorine and oxygen with hydroxide were obtained in a hydrolysis process, producing the complex (2) [{(q 5-C5Me5)Zr(p2-Cl)}3(p3-O)(p-OH)]

[0057] Equation 1

[0058] [{(q 5 -C5Me5) ZrCl2}2-as-lc] - ► 3{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc + 2H2O - ►

[0059] (1)

[0060] - ► 2{(q 5 -C5Me5)Zr(p2-Cl)2)}3(p3-O)(p-OH) + 3HCI

[0061] (2)

[0062] In this analysis, the hydrolysis process of (1 ) [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc]. By deliberate hydrolysis (1) with a stoichiometric excess of water in toluene for 32 hours at 80 °C, the yellow trinuclear complex (2) was successfully obtained in 70% yield. The reaction led to the isolation of yellow crystals, representative of complex (2) [{(q 5 -C5Me5)Zr(p2-Cl)2)}3(p3-O)(p-OH)] as shown in equation 1. Complexes (1) and (2) were characterized by NMR 1 H, elemental analysis and X-ray diffraction. The NMR spectrum 1H of complex (1) in C6D6 shows different resonances for the different protons in the complex. A singlet at 1.86 ppm corresponds to the methyl groups of the ri 5 -C5Me5(Cp*). For the as-indacene fraction, a doublet at 4.58 ppm and a triplet at 4.69 ppm are representative of different methylene proton environments, respectively. The triplet is characterized by a coupling constant (J) of 3.2 Hz, which provides information about the coupling interactions within this part of the molecule. Aromatic protons are assigned a singlet at 6.00 ppm. The residual signal from the deuterated benzene solvent appears at 7.14 ppm. (Fig. S1) Notably, the observed signals are consistent with those of previously reported zirconium complexes, confirming the expected chemical environment of the protons.

[0063] The NMR spectrum 1H of complex (2) in C6D6 shows different resonances for the different protons in the complex. (Fig. S2) Three different singlets at 2.01, 1.76 and 1.55 ppm, assigned to the methyl groups of three ligands q 5 -C5Me5(Cp*), each in different coordination environments due to the different interactions between the zirconium and chloride. Additionally, a doublet at 4.39 ppm is attributed to a hydroxyl proton (OH) involved in a bridging interaction (p-OH) between the zirconium centers, suggesting hydrogen bonding or metal coordination. The residual signal from the deuterated benzene solvent appears at 7.14 ppm.

[0064] Example 4. Comparative results. Polymerization of ethylene.

[0065] To demonstrate the catalytic advantage of the complexes of the invention, ethylene polymerizations were carried out under the same conditions reported in patent CL202203464 and in the publication Journal of Molecular Structure, 1309 (2024) 138163, by Y. Dibdalli et al. The complexes evaluated included Complex (1) [{(q 5 -C5Me5)Zr(p2-Cl)}2- as-lc], the Complex (2) [{(q 5 [(Cp*ZrCl2)2-as-lc] (CL202203464) [C5Me5)Zr(p2-Cl)3(p3-O)(p-OH)], and the reference complex [(Cp*ZrCl2)2-as-lc] (CL202203464). Polymerizations were carried out using ethylene as the monomer, MAC as the co-catalyst, 0.125 mg of catalyst (0.17 pmol of Zr), and toluene (30 mL) as the solvent, at 60 °C and 2 bar for 30 minutes. Al / Zr ratios of 6000, 3000, and 1500 were evaluated. The results are summarized in Table 1.

[0066] The Complex (1) [{(q 5The complex [-C5Me5)Zr(p2-Cl)}2-as-lc] showed the highest catalytic activity and polymer yield at all Al / Zr ratios. For example, at Al / Zr = 6000, it produced 4.10 g of polymer with an activity of 12,200 kg PE / mol Zr-h-bar and a melting temperature (Tm) of 131.2 °C, indicating high crystallinity and chain regularity. Even at lower Al / Zr ratios, Complex (1) maintained good activity and control over the polymer.

[0067] The Complex (2) [{(q 5 [(C5Me5)Zr(p2-Cl)}3(p3-O)(p-OH)] showed intermediate activity, producing polymers with slightly lower yield and Tm, between 130.1–130.4 °C, with slightly reduced stability compared to complex (1). The reference complex [(Cp*ZrCl2)2-as-lc] produced polymers with Tm values ​​ranging from 130.0 to 130.8 °C and with lower activity and overall yield.

[0068] Table 1. Ethylene polymerization activities of complexes (1) and (2)

[0069] The comparative data in Table 1 clearly demonstrate that both Complexes (1) and (2) of the invention outperform the reference complex (CL202203464) under identical polymerization conditions. Complex (1) exhibited the highest catalytic activity under all evaluated conditions. At an Al / Zr ratio of 6000, it produced 4.10 g of polymer with an activity of 12,200 kg PE / mol Zr-h-bar, which is higher than Complex (2) (3.05 g and 9,200 kg PE / mol Zr-h-bar) and the reference complex [(Cp*ZrCl2)2-as-lc] (2.77 g and 8,275.6 kg PE / mol Zr-h-bar). Even at lower Al / Zr ratios (3000 and 1500), Complex (1) consistently outperformed both Complex (2) and the reference in polymer yield and activity. Therefore, [{(q 5-C5Me5)Zr(p2-Cl)}2-as-lc] (1) clearly demonstrates the greater catalytic efficiency, confirming its superior performance compared to the previously reported complex (CL202203464, Journal of Molecular Structure, 1309 (2024) 138163). Example 5. Structural and Mathematical Analyses

[0070] 5.1 Description of the crystal structure

[0071] The appropriate crystals of the complex (1) [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc] and of the complex (2) [{(n 5 -C5Me5)Zr(p2-Cl)}3(p 3 The -O)(p-OH)] cells for X-ray diffraction were obtained from a toluene / dichloromethane solution. A single crystal with approximate dimensions of 0.31 × 0.18 × 0.04 mm was used for cell determination and data collection. 3 (1), 0.17 x 0.15 x 0.1 mm 3 (2). The network constants were determined by the least squares method using F 2Data were recorded using x2h scan mode up to a maximum h value of 26.98. All intensities were corrected for polarization and Lorentz absorption effects using an empirical w scan, with maximum (Tmax) and minimum (Tmin) transmission values ​​of 0.615. The structure was solved by direct methods using SHELXS-86 and refined by full-array least-squares methods in F 2 The complete dataset was analyzed using SHELXL-97. Anisotropic thermal parameters were refined for non-hydrogen atoms, and hydrogen atoms were introduced at calculated positions. Crystal data, data collection, and refinement details are given in Table 2. X-ray diffraction data were collected on complexes (1) and (2) at 150 K and 100 K, respectively. The ORTEP plot for complexes (1) and (2) is shown in Figures 1 and 2.

[0072] Table 2. Crystal data for (1) [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc] and (2) [{(q 5 -C5Me5)Zr(p2- Cl)2)}3(P3-O)(p-OH)]

[0073] Empirical formula C32H38Cl2Zr2 (1) C3o H4e Cl6O2Zr3(2)

[0074] Formula weight 675.96 925.03

[0075] Temperature / K 150.0 100.0

[0076] Orthorhombic Monoclinic Crystal System

[0077] Space group Pnna P21 / ca / Á 9.1749(3) 11 .44(2) b / Á 14.5375(5) 20.52(4) c / Á 21 .1981(7) 15.96(3) a / ° 90 90 p / ° 90 107.90 (5) y / ° 90 90 Volume / Á 2827.40(16) 3565.23

[0078] Z 4 4 pcalcg / cm 3 1,588 1,724 / mm' 1 0.946 1.337

[0079] F(000) 1376.0 1856.0

[0080] Glass size mm3 0.31 x 0.18 x 0.04 0.17 x 0.15 x 0.1

[0081] MoKa radiation (7=0.71073) MoKa (A= 0.71073)

[0082] Range 20 for the collection of From 4,838 to 61,016 From 5,364 to 56,844 dates / 0

[0083] Index ranges -12< h< 13, -20< K<20,- -15< h< 15,-27< K<27,

[0084] 29 < l < 30 -21 < l < 21

[0085] Connected Reflections 49504 49504

[0086] Independent reflections 4319 [Rint = 0.0434, 8958 [Rint = 0.0453, Rsigma = 0.0224] Rsigma = 0.0175]

[0087] Data / restrictions / parameters 4319 / 2 / 246 8958 / 0 / 385

[0088] Goodness of fit in F2 1.067 1.146 final R indices [l>=2o(l)] R1 = 0.0320, wR2 = 0.0653 R1 = 0.0488, wR2 = 0.1255 final R indices [all data] R1 = 0.0489, wR2 = 0.0729 R1 = 0.0701, wR2 = 0.1645

[0089] Largest difference 0.39 / -0.34 3.68 / -1.77 peak / hole / eA-3

[0090] The ORTEP of the complex [{(q 5 -C5Me5)Zr(2-Cl)}2-as-lc] (1) in Fig. 1, consists of discrete molecules with two zirconium (Zr) atoms. These Zr atoms (Zr2 and Zr3d) are bonded to two bridging chloride ions and are coordinated q 5to the pentamethylcyclopentadienyl rings (Cp*) and the as-indacene bridging ligand (as-lc). The Zr2-Zr3 distance in complex (1) is observed to be 3.485 Å. This distance falls within the range reported for other p-Cl-bridged Zr(III) compounds, which varies between 3.233 Å and 3.863 Å. Comparison indicates that the Zr2-Zr3 distance in our complex is consistent with these values, reflecting the structural flexibility of Zr(III) in bridging arrangements.

[0091] The structural parameters listed in Table 3 illustrate the geometric relationships within complex 1. The Zr₂-Cl₉-Zr₃ angle of 91.3° indicates a nearly right-angled geometry, typical of Zr(III) complexes with p-Cl bridges. The centroid distances of 2.487 Å between Zr₂ and Zr₃ and the Cp* ligands, along with the angles between the centroids and the Zr atoms, further define the structure. All intramolecular Zr₂-C and Zr₃-C distances relative to the as-indacene and Cp* ligands range from 2.4 to 2.8 Å, contributing to the overall geometry and stability of the complex.

[0092] Chloride bridges significantly influence the geometry of this intriguing zirconium complex, affecting both its electronic and magnetic properties. Magnetic susceptibility measurements, illustrated by the vibrating sample magnetometer (VSM) graph, further support the interpretation of the observed diamagnetism. The VSM data, as shown in Fig. S3, reveal a linear MH curve, indicative of effective unpaired electron cancellation. This behavior is attributed to the d electronic configuration. 1 of the Zr(lll) centers and the strong antiferromagnetic coupling between the Zr centers, which gives rise to the observed diamagnetism. The data support the conclusion that the magnetic moments of the Zr(lll) centers are neutralized due to strong Zr...Zr interactions, leading to an overall diamagnetic response.

[0093] Table 3. Selected bond lengths [A] and angles [°] for (1 )

[0094] [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-ic]

[0095] Zr2 - C(1) Cp* 2,429(3)

[0096] Zr2 - C(2) Cp* 2,523(3)

[0097] Zr2 - C(3) Cp* 2,581 (3)

[0098] Zr2 - C(4) Cp* 2,597(3)

[0099] Zr2 - C(5) Cp* 2,521 (3)

[0100] Zr2 -Cp* promedio 2,520(3) Zr3 -Cp* promedio 2,512(14)

[0101] Zr2-Cl9 2,576(5)

[0102] Zr3-Cl9d 2,575(3)

[0103] Zr3 - C(11 ) as-indaceno 2,447(4)

[0104] Zr3 - C(12) as-indaceno 2,527(3)

[0105] Zr3 - C(13) as-indaceno 2,467(4)

[0106] Zr3 - C(14) as-indaceno 2,503(3)

[0107] Zr3 - C(15) as-indaceno 2,514(12)

[0108] Zr3 - promedio del as-indaceno 2,502(3)

[0109] Zr2 - promedio delas-indaceno 2,514(12)

[0110] Ángulo C(1)- Zr3-CL9 93,46(11)

[0111] Angle C(2)- Zr3-Cl9 125.97(14)

[0112] Angle C1- Zr2-CL9D 98.32(13)

[0113] Angle C(1)- Zr2-Cl(9D) 131 ,35(14)

[0114] Angle Zr2-CL9-ZR3 91 ,3 (8)

[0115] Corresponding distances Zr3- 3,485(2)

[0116] Zr2

[0117] The crystals of (2) [{(r| 5 -C5Me5)Zr(p2-Cl)2}3(p3-O)(p-OH)] were grown by cooling a concentrated dichloromethane solution with pentane diffusion. A single-crystal X-ray diffraction experiment was performed to resolve the crystal structure. Atomic connectivity is clearly established. Structure determination reveals that, in the ORTEP of complex (2) in Fig. 2, it consists of three Cp*Zr(p2-Cl)2 units bridged by a triply connected oxygen atom (p3-O) at the center of the structure and a hydroxide ion (p-OH) on the periphery of the resulting Zr3 ring.

[0118] The structural parameters listed in Table 4 provide detailed information on bonding and coordination within the complex. The distances between the zirconium centers, Zr3-Zr2, Zr3-Zr1, and Zr2-Zr3, are measured at 3.68 Å, 3.27 Å, and 3.60 Å, respectively. The Cp* ligands are strongly coordinated to the zirconium atoms, with distances to the Cp* centroids of 2.587 Å. The Cg(Cp*)-Zr distances are consistent at 2.50 Å, with bond angles of 115.3°, 121.5°, and 121.5°, respectively. o and 135.4°.

[0119] A comparative analysis of complex (2) with the p3-O bridged Zr trimer reported by Pascual Royo et al. in 1990 reveals both similarities and differences. Royo's trimer, derived from the partial hydrolysis of Cp*ZrCl3, has a similar p3-O bridged structure, but with a greater degree of oxygen bridging and a different ligand environment. Our complex 2 incorporates a hydroxide group, resulting in distinct structural characteristics. Specifically, the Zr-O distances in our complex are 2.20 Å and 1.98 Å, with corresponding angles of 106.3 Å. o and 112.9°. Furthermore, the distances Zr3-H11 and H11-011 are 2.30 Å and 0.83 Å, respectively, with a link angle of 51.2°. o for Zr3-H11-011. The presence of Cp* ligands and the hydroxyl group contribute to these unique structural features. Click or tap hero to enter text.

[0120] Table 4. Selected link lengths [A] and angles [°] for

[0121] (2) [{(r| 5 -C5Me5)Zr(p2-Cl)2)}3(p3-O)(p-OH)]

[0122] Zr1 - C(12) Cp* 2.509(7)

[0123] Zr1 - C(13) Cp* 2.503(6)

[0124] Zr1 - C(14) Cp* 2.505(8)

[0125] Zr1 - C(15) Cp* 2.533(8)

[0126] Zr1 - C(16) Cp* 2.519(8)

[0127] Zr2 -Cp* average 2.502(6)

[0128] Zr3 -Cp* average 2.530(6)

[0129] Zr1-Cl4 2.667(4)

[0130] Zr2-Cl4 2.566(4)

[0131] Angle Zr1-CL4-ZR2 87.75(12)

[0132] Zr1-CL5 2.685(4)

[0133] Zr1-CL5 2.605(4)

[0134] Angle Zr1-Cl5-Zr2 86.55(12)

[0135] Zr1-CL6 2.454(6) Zr2-CL7 2.432(4)

[0136] Zr2-Cl8 2.556(4)

[0137] Zr3-CL8 2.663(4)

[0138] Angle Zr2-CL8-ZR3 89.67(19)

[0139] Zr3-CL9 2.426(4)

[0140] Zrl-010 2,313(6)

[0141] Zr2-O10 2,220(6)

[0142] Zr3-O10 2,204(4)

[0143] Angle Zr1-O10-ZR2 106,308(11)

[0144] Angle Zr1-O10-ZR3 92.85(15)

[0145] Zrl-011 1 ,982(5)

[0146] Zr3-011 1 ,969(5)

[0147] Angle Zr1-011-ZR3 111 ,90(2)

[0148] Zr3-H11 2,380((6)

[0149] O11-H11 0.834(9)

[0150] Zr3-H11-011 51 ,25(3)

[0151] Solid-state structure analysis shows that complex (1) crystallizes in an orthorhombic Pnna space group with four molecules per unit cell. Similarly, complex (2) crystallizes in a monoclinic P21 / c space group with four molecules per unit cell (Figs. S4 and S5). Furthermore, the structure of complex (1) revealed that the molecule is Cs symmetric and the fragment [{(q 5-C5Me5)Zr(p2-Cl)}2-as-lc] has an anticonfiguration, indicating that the Cp*Zr(p2-Cl)2 fragments are positioned on opposite sides of the as-indacene ligand.

[0152] Compound (2) consists of three Cp*Zr(p2-Cl)2 units linked by a triple-bonded oxygen atom (p3-O) at the center of the structure, and a hydroxide ion (p-OH) on the periphery of the resulting Zr3 ring. The presence of oxygen atoms suggests the involvement of oxygen bridges with a hydroxide group present in the structure. 5.2 DFT Calculations

[0153] In order to explore the bonding characteristics in (1) and (2), compared to the respective precursor [{(r| 5-C5Me5) ZrCl2}2-as-lc], we carried out DFT calculations for (2), two possible isomers are evaluated, namely, Isol and Iso2, Fig. 3 with Iso1 the experimentally characterized structure and Iso2, with all the C5Me5 rings located above the Zr3 ring. This latter isomer is unfavorable by 5.5 kcal / mol. The analysis of the different energy terms that contribute to the formation of the overall complex (AE¡ nt ) from the energy decomposition analysis, explains the Pauli repulsion of four electrons and two orbits (AE Pau i) due to the destabilizing steric repulsion, the electrostatic and orbital character of the interaction (AE eLs tat and AE or b, respectively), and the London dispersion term (AEd¡ Sp), unravels the origin of the preference for the characterized structure (Iso1). The comparison between the respective energy terms related to Iso1 and Iso2, denoted by Table 4 of AAE, shows negligible variation for the stabilizing terms (AE eLs tat, AE or by AEd! S p), which suggests that the stabilizing bond characteristics remain similar between these isomers. More considerable differences are found for the steric repulsion explained by AE Pau ii, which is the main term that determines the observed experimental structure. Furthermore, the difference of 5.5 kcal / mol suggests a plausible flexibility of (2).

[0154] Table 5. Energy decomposition analysis for the general complex into two isomers, namely Iso1 and Iso2, taking into account their energy difference (EAE). Values ​​in kcal / mol.

[0155] In order to estimate the charge distribution in (2), the electrostatic potential isosurface was calculated, providing the location of the electron-deficient and electron-rich regions. The electron-deficient sites are located in the -Me groups of the C5Me5 rings. Interestingly, a well-defined electron-rich region is found above the central oxygen atom in the Zr3 frame (Fig. 4), with a calculated minimum electrostatic potential surface value of -50.0 kcal / mol (Vmin). This provides suitable characteristics for further exploration of the active sites for catalytic performance in olefin polymerization.

[0156] Finally, the Zr-ligand interaction is evaluated for the parent precursor ([{(r| 5 -C5Me5) ZrCl2}2- as-lc]), (1) and (2), in order to estimate the variations of the charge Zr(IV)^Zr(lll)^Zr(IV). The interaction energy calculated for each Zr-C5Me5 coordination amounts to -212.6 kcal for the precursor ([{(r| 5-C5Me5) ZrCl2}2-as-lc]), which decreases to -191.0 kcal / mol in (1), indicating differences in coordination strength from the Zr(IV) to the Zr(III) case. For (2), three different coordination spheres are given for each Zr center, leading to three different Zr-C5Me5 interaction energies of -217.1 kcal / mol for the metal center Zr(Cl)4(O), -217.4 kcal / mol for Zr(Cl)3(O)(OH), and -223.1 kcal / mol for Zr(Cl)2(O)(OH), which are in a similar range to that calculated for [{(r| 5 -C5Me5) ZrCl2}2-as-lc] precursor. Therefore, Zr(IV) species exhibit a stronger metal-ligand interaction towards the C5Me5 coordination. For the interaction with the as-lc ligand, it is calculated to be -248.5 kcal / mol for the precursor [{(q 5-C5M e5) ZrCl2}2-as-lc], and -250.3 kcal / mol in (1), denoting very similar values ​​in contrast to the Zr-C5Me5 interaction trend, suggesting that to maximize the interaction with the as-lc ligand, the subsequent interaction is reduced in (1).

Claims

CLAIMS 1. A complex catalyst, CHARACTERIZED in that it corresponds to the formula (2):

2. A catalyst complex CHARACTERIZED in that it corresponds to a reaction intermediate for obtaining the catalyst complex according to claim 1 and having formula (1):

3. A process for preparing a catalyst complex according to claim 1, CHARACTERIZED in that it comprises the steps of: a) preparing the complex (1) [{(q 5 -C5Me5)Zr(p2-Cl)}2-as-lc] by the reaction of [{(q 5 - C5Me5)ZrCl2}2-as-lc] in the presence of sodium and mercury in toluene, and b) prepare the complex (2) [{(q 5 -C5Me5) Zr(p2-Cl)2)}3(p3-O)(p-OH)] by the reaction of [(ZrCp*(p2-Cl))2-as-lc] in the presence of water in toluene, where the process is represented by Scheme I below:

4. The process for the preparation of a catalyst complex according to claim 3, CHARACTERIZED in that the method comprises the following steps: a. Mixing as a precursor [{(q 5 -C5Me5)ZrCl2}2-as-lc] with a sodium amalgam in toluene, at room temperature, for a period of 36 to 60 hours; b. Heat the mixture under reflux for a period of 1 to 3 hours; c. Cool to room temperature; d. Filter the solution obtained in the previous step, recovering the residue; e. Wash the residue with toluene until the washing solution becomes colorless, obtaining complex (1). f. Mix complex (1) with a stoichiometric excess of water, stirring it in toluene at a temperature of 65 to 100 °C for a period of 24 to 40 hours; g. Filter the mixture obtained in the previous step and dry it, yielding complex (2).

5. The process for the preparation of a catalyst complex according to claim 4, CHARACTERIZED in that in step (a) a sodium amalgam of between 0.4 and 0.6% is used.

6. The process for the preparation of a catalyst complex according to claim 4, CHARACTERIZED in that in step (f) the temperature is 80°C.

7. The process for the preparation of a catalyst complex according to claim 4, CHARACTERIZED in that a ratio of the precursor [{(q 5 - C5Me5)ZrCl2}2-as-lc] to the sodium amalgam of between 30:1 to 20:1 by weight, preferably 30:1 .

8. The process for preparing a catalyst complex according to claim 4, CHARACTERIZED in that toluene is used in a weight:volume ratio of precursor to toluene of between 10:1 and 7:

1.

9. The process for preparing a catalyst complex according to claim 4, CHARACTERIZED in that to continue the reaction and obtain the complex (2) a ratio of between 1:1 and 1:2 weight:volume of the complex (1) and toluene is considered.

10. Use of the catalyst complex according to claim 1, CHARACTERIZED in that it is used to catalyze the polymerization of ethylene.

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