Dicyanamide-coordinated mononuclear cobalt complex and its preparation method and application

Abstract

The present invention relates to a mononuclear cobalt complex coordinated by dicyanamide and its preparation method and application, belonging to the technical field of coordination compounds. The molecular formula of the mononuclear cobalt complex is Co(bim)4[N(CN)2]2, triclinic system, P-1 space group, and unit cell parameters are α=65.607(11)°, β=89.647(12)°, and γ=68.197(12)°. In the mononuclear cobalt complex provided by the present invention, dicyanamide is not used as a stacking block to link cobalt ions, but only as a monodentate ligand to form a mononuclear complex with cobalt ions. At the same time, the complex has paramagnetism, exhibits slow magnetic relaxation performance under an external field, and can be used for the preparation of molecular-based magnetic materials.

Description

Technical Field

[0001] The invention belongs to the technical field of complexes and relates to a dicyanamide-coordinated mononuclear cobalt complex and a preparation method and application thereof. Background Art

[0002] Cobalt complexes, an important class of transition metal compounds, have attracted considerable attention due to their wide-ranging applications in catalysis, magnetic materials, electrochemistry, and molecular recognition. In recent years, the design and preparation of cobalt complexes has become a hot topic in coordination chemistry and materials chemistry. By manipulating the type and coordination mode of the ligand, the structure and properties of cobalt complexes can be precisely tailored to meet the needs of diverse applications.

[0003] Dicyanamide ([N(CN)2]-), a versatile ligand, has attracted extensive attention in the study of organometallic complexes due to its diverse coordination modes, strong electron-donating capacity, and stability toward metal ions. However, relatively few studies exist on mononuclear cobalt complexes coordinated with dicyanamide and cobalt ions, particularly regarding their structural design, preparation methods, and functional applications. Currently, research on the introduction of dicyanamide ligands and their precise coordination relationships with cobalt complexes remains limited, hindering the in-depth development and application of these complexes in fields such as coordination chemistry.

[0004] Therefore, designing a mononuclear cobalt complex coordinated by dicyanamide, developing an efficient and simple preparation method, and exploring its potential applications in related fields are of great scientific significance and practical value. Summary of the Invention

[0005] The purpose of the present invention is to study, discover and provide the crystal structure of a mononuclear cobalt complex coordinated by dicyanamide and its preparation method through a crystallographic method, and to explore its application in the field of molecular magnetic materials.

[0006] In a first aspect of the present invention, a crystal structure of a mononuclear cobalt complex is provided, wherein the molecular formula of the mononuclear cobalt complex is Co(bim)4[N(CN)2]2, wherein bim is 1-allylimidazole; the crystallographic parameters of the mononuclear cobalt complex are: triclinic system, P-1 space group, unit cell parameters α=65.607(11)°, β=89.647(12)°, γ=68.197(12)°, and the mononuclear cobalt complex is obtained by coordinating dicyanamide with cobalt ions in a monodentate coordination mode. The mononuclear cobalt complex is an octahedral cobalt single-ion magnet.

[0007] In some embodiments, the unit cell volume of the mononuclear cobalt complex is

[0008] In some embodiments, the number of molecules Z in the unit cell of the mononuclear cobalt complex is 1.

[0009] The second aspect of the present invention provides a method for preparing the above-mentioned mononuclear cobalt complex, specifically: adding anhydrous CoCl2 and sodium dicyanamide to anhydrous acetonitrile, stirring, and then adding 1-allylimidazole to react. After the reaction is completed, the reaction solution is placed in an ether atmosphere and allowed to stand for 7-10 days to obtain the mononuclear cobalt complex.

[0010] In some embodiments, the stirring time is 20 to 40 minutes.

[0011] In some embodiments, the reaction time is 2 to 4 hours.

[0012] In some embodiments, the molar ratio of anhydrous CoCl2 to sodium dicyanamide is 1:2.

[0013] In some embodiments, every 0.5 mmol of CoCl2 corresponds to 2.0-2.5 mmol of 1-allylimidazole.

[0014] In some embodiments, each 0.5 mmol of CoCl2 corresponds to 10-15 mL of anhydrous acetonitrile.

[0015] The mononuclear cobalt complex prepared by the invention has paramagnetism and exhibits slow magnetic relaxation properties under an external magnetic field.

[0016] In a third aspect of the present invention, there is provided a use of the above-mentioned mononuclear cobalt complex or the mononuclear cobalt complex prepared by the above-mentioned preparation method in the preparation of a molecule-based magnetic material.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The mononuclear cobalt complex prepared by the present invention is stable in air at room temperature, has paramagnetism, and exhibits slow magnetic relaxation properties under an external magnetic field, and can be used in the preparation of molecular-based magnetic materials.

[0019] (2) The cobalt complex prepared by the present invention is a mononuclear complex, and the preparation method is simple to operate, has good controllability, and high reproducibility. The obtained complex has high purity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The crystal structure diagram of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 provided by the present invention;

[0021] Figure 2This is a temperature-dependent magnetic susceptibility test diagram of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 provided by the present invention;

[0022] Figure 3 A field-dependent magnetization intensity curve of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 provided by the present invention;

[0023] Figure 4 AC magnetic susceptibility diagram of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 provided by the present invention under different external magnetic fields;

[0024] Figure 5 The imaginary part AC magnetic susceptibility diagram of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 provided by the present invention is frequency dependent;

[0025] Figure 6 The present invention provides a diagram of the imaginary AC magnetic susceptibility of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 that is temperature-dependent. DETAILED DESCRIPTION

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0027] The embodiment of the present invention provides a mononuclear cobalt complex, the molecular formula of the mononuclear cobalt complex is Co(bim)4[N(CN)2]2, wherein bim is 1-allylimidazole; the crystallographic parameters are: triclinic system, P-1 space group, unit cell parameters are α=65.607(11)°, β=89.647(12)°, γ=68.197(12)°.

[0028] The present invention also provides the unit cell volume of the mononuclear complex The number of molecules Z in the unit cell of the mononuclear complex is 1.

[0029] To further illustrate the present invention, the mononuclear cobalt complex provided by the present invention, its preparation method and application are described in detail below with reference to the examples.

[0030] The reagents used in the following examples are all commercially available. The raw materials used in the examples of the present invention are shown in Table 1.

[0031] Table 1: Raw materials used in the examples

[0032]

[0033] Example 1

[0034] Dissolve 0.5 mmol of CoCl₂ in 10 ml of anhydrous acetonitrile, then add 1 mmol of sodium dicyanamide. Stir for 30 minutes, then add 2 mmol of 1-allylimidazole. Allow to react at room temperature for 3 hours, then filter to obtain a blue solution. Transfer the solution to a test tube. Transfer the test tube to a sealed container filled with ether for diffusion. After 10 days, crystals of the mononuclear cobalt complex Co(bim)₄[N(CN)₂]₂ are obtained in a 63% yield.

[0035] Example 2

[0036] Dissolve 0.5 mmol of CoCl₂ in 10 ml of anhydrous acetonitrile, then add 1 mmol of sodium dicyanamide. Stir for 30 minutes, then add 2.5 mmol of 1-allylimidazole. Allow to react at room temperature for 3 hours, filter the resulting blue filtrate, and transfer it to a test tube. Finally, transfer the test tube to a sealed container filled with ether for diffusion. After 7 days, crystals of the mononuclear cobalt complex Co(bim)₄[N(CN)₂]₂ are obtained in a 60% yield.

[0037] Example 3

[0038] Dissolve 0.5 mmol of CoCl₂ in 15 ml of anhydrous acetonitrile, then add 1 mmol of sodium dicyanamide. Stir for 30 minutes, then add 2.0 mmol of 1-allylimidazole. Allow to react at room temperature for 3 hours, then filter to obtain a blue solution. Transfer the solution to a test tube, which is then placed in a sealed container filled with ether for diffusion. After 13 days, crystals of the mononuclear cobalt complex Co(bim)₄[N(CN)₂]₂ are obtained in a 61% yield.

[0039] The following determinations were performed using the mononuclear cobalt complex Co(bim)4[N(CN)2]2 prepared in Example 1 as a sample:

[0040] (1) Crystal structure determination

[0041] Single crystals of appropriate size were selected under a microscope and structured at room temperature on a Bruker SMARTApex IICCD single crystal instrument using a graphite-monochromatized molybdenum target. Data were collected and the unit cell determined using the APEXII program. Structural data were normalized and absorption corrected using the SAINT and SADABS programs. Structural elucidation was performed using the SHELXTL-97 program. All non-hydrogen atomic coordinates were obtained by difference Fourier synthesis. Atomic coordinates and anisotropic temperature factors were corrected using full-matrix least-squares methods. All hydrogen atoms were theoretically added. Figure 1The structure of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 is shown in Table 2. Crystallographic data and coordination bond lengths are shown in Table 3.

[0042] Table 2 Crystallographic data of mononuclear cobalt complex Co(bim)4[N(CN)2]2

[0043]

[0044] Table 3: Coordinate bond lengths and bond angles of the mononuclear cobalt complex Co(bim)4[N(CN)2]2

[0045]

[0046]

[0047] In the mononuclear complex provided by the present invention, both 1-allylimidazole and dicyanamide are coordinated to the cobalt ion using a monodentate coordination mode. The central cobalt ion adopts a [CoN6] coordination mode, in which four nitrogen atoms are derived from four different 1-allylimidazoles and the remaining two nitrogen atoms are derived from two different dicyanamides, resulting in a distorted octahedral coordination configuration calculated using Shape software (Table 3).

[0048] Table 3: CShM values ​​of octahedral cobalt single-ion magnet Co(bim)4[N(CN)2]2

[0049] Configuration CShM value HP-6 (hexagonal) 31.907 PPY-6 (Pentagonal Pyramid) 29.752 OC-6 (octahedron) 0.065 TPR-6 (Triangular Prism) 16.332 JPPY-6 (Pentagonal Pyramid) 33.224

[0050] (2) Magnetic Properties: The complex obtained in Example 1 was analyzed by elemental analysis, yielding the following results: Elemental Analysis (%): Calculated: C 53.93, H 5.17, N 31.45; Exp.: C 53.91, H 5.19, N 31.44. The elemental analysis results were consistent with the chemical formula shown by the single crystal test data.

[0051] (3) Magnetic performance characterization:

[0052] Magnetic measurements were performed using a Quantum Design MPMS SQUID VSM magnetic measurement system. DC magnetic susceptibility was measured at a temperature of 2.0–300 Kelvin (2.0–300 K) and a magnetic field of 1000 Oe. Magnetization intensity was measured at temperatures of 2 K, 3 K, and 5 Kelvin (0–7 T). AC magnetic susceptibility was measured over a frequency range of 1–1000 Hz, a temperature range of 2.0–6.0 Kelvin (2.0–6.0 K), and a DC magnetic field of 1000 Oe.

[0053] like Figure 2 As shown in the figure, under an external DC magnetic field of 1000 Oe, when the temperature reaches 300 K, the χM T value is 2.99cm 3 Kmol -1 , which is much larger than the theoretical value (1.875 cm) when only the spin of Co(II) ions is considered (S=3 / 2, g=2). 3 Kmol -1 ), which indicates that there is a large magnetic anisotropy in the complex. The axial zero-field splitting parameter D value is +67.68cm by PHI fitting. -1 The magnetization intensity curve is as follows: Figure 3 As shown in the figure, with the increase of magnetic field strength, the magnetization intensity increases continuously, reaching a maximum value of 2.28Nβ at 2K and 7T, and has not reached saturation, indicating that there is a large magnetic anisotropy in the complex.

[0054] The AC magnetic susceptibility test shows that at 2.0K, the complex exhibits a frequency-dependent imaginary magnetic susceptibility signal under an external magnetic field ( Figure 4 Under an external magnetic field of 1000 Oe, the imaginary AC magnetic susceptibility of the complex shows a significant frequency dependence ( Figure 5 ) and temperature dependence ( Figure 6 ).

[0055] In summary, the mononuclear cobalt complex prepared in the present invention has paramagnetism and can exhibit slow magnetic relaxation properties under an external magnetic field, and can therefore be used as a molecular-based magnetic material.

Claims

1. A dicyanamide-coordinated mononuclear cobalt complex, characterized in that: The molecular formula of the mononuclear cobalt complex is Co(bim)4[N(CN)2]2, wherein bim is 1-allylimidazole, and the crystallographic parameters are: triclinic system, P-1 space group, unit cell parameters are α=65.607(11)°,β= 89.647(12)°,γ=68.197(12)°; The mononuclear cobalt complex is obtained by coordinating dicyanamide with cobalt ions in a monodentate coordination mode.

2. The mononuclear cobalt complex according to claim 1, characterized in that The unit cell volume of the mononuclear cobalt complex is 3. The mononuclear cobalt complex according to claim 1, characterized in that The number of molecules Z in the unit cell of the mononuclear cobalt complex is 1.

4. A method for preparing the mononuclear cobalt complex according to any one of claims 1 to 3, characterized in that: include: Anhydrous CoCl2 and sodium dicyanamide are added to anhydrous acetonitrile, stirred, and then 1-allylimidazole is added to react. After the reaction is completed, the reaction solution is placed in an ether atmosphere and allowed to stand for 7-10 days to obtain the mononuclear cobalt complex.

5. The preparation method according to claim 4, characterized in that The stirring time is 20 to 40 minutes.

6. The preparation method according to claim 4, characterized in that The reaction time is 2 to 4 hours.

7. The preparation method according to claim 4, characterized in that The molar ratio of the anhydrous CoCl2 to sodium dicyanamide is 1:

2.

8. The preparation method according to claim 7, characterized in that Every 0.5 mmol of CoCl2 corresponds to 2.0-2.5 mmol of 1-allylimidazole.

9. The preparation method according to claim 7, characterized in that Each 0.5 mmol of CoCl2 corresponds to 10-15 mL of anhydrous acetonitrile.

10. Use of the mononuclear cobalt complex according to any one of claims 1 to 3 or the mononuclear cobalt complex prepared by the preparation method according to any one of claims 4 to 9 in molecule-based magnetic materials.

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