Dicyanamide radical coordinated mononuclear cobalt complex as well as preparation method and application thereof

Abstract

The invention relates to a dicyandiamide radical coordinated mononuclear cobalt complex as well as a preparation method and application thereof, and belongs to the technical field of coordination compounds. The molecular formula of the mononuclear cobalt complex is Co (bim) 4 [N (CN) 2] 2, the mononuclear cobalt complex has a triclinic system and a P-1 space group, and cell parameters are as follows: # imgabs0 # alpha = 65.607 (11) degrees, beta = 89.647 (12) degrees, and gamma = 68.197 (12) degrees. In the mononuclear cobalt complex provided by the invention, the dicyandiamide radical does not serve as a stacking block to link cobalt ions, but only serves as a monodentate ligand to form the mononuclear complex with the cobalt ions. Meanwhile, the complex has paramagnetism, shows slow magnetic relaxation performance under an external field, and can be used for preparing molecule-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] As an important class of transition metal compounds, cobalt complexes have attracted much attention due to their wide applications in catalysis, magnetic materials, electrochemistry, molecular recognition and other fields. In recent years, the design and preparation of cobalt complexes have become a hot area in coordination chemistry and materials chemistry research. By regulating the type of ligand and the coordination mode, the structure and properties of cobalt complexes can be precisely controlled to meet the needs of different applications.

[0003] As a multifunctional ligand, dicyanamide ([N(CN)2]-) has attracted extensive attention in the study of metal organic complexes due to its rich coordination modes, strong electron donation ability and stability to metal ions. However, there are relatively few studies on mononuclear cobalt complexes coordinated by dicyanamide and cobalt ions in the prior art, especially in terms of structural design, preparation methods and functional applications. At present, there are still certain limitations in the introduction of dicyanamide ligands and the precise coordination relationship between them and cobalt complexes, which restricts the in-depth development and application of such complexes in coordination chemistry and other fields.

[0004] Therefore, it is of great scientific significance and practical value to design a mononuclear cobalt complex coordinated by dicyanamide, develop an efficient and simple preparation method, and explore its potential applications in related fields. 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 a preparation method thereof by 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 are 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, which is specifically: adding anhydrous CoCl2 and sodium dicyanamide to anhydrous acetonitrile, stirring and then adding 1-allylimidazole to react. After the reaction is completed, placing the reaction solution in an ether atmosphere and standing 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, every 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, exhibits slow magnetic relaxation properties under an external magnetic field, and can be applied to 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 a 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 2The 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 The 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 frequency-dependent imaginary AC magnetic susceptibility diagram of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 provided by the present invention;

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

[0026] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in combination with the embodiments. Obviously, the described embodiments 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 creative work 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] In order to further illustrate the present invention, the mononuclear cobalt complex provided by the present invention and its preparation method and application are described in detail below in conjunction with 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] Take 0.5mmol CoCl2 and dissolve it in 10ml anhydrous acetonitrile, then add 1mmol sodium dicyanamide, stir for 30min, and then add 2mmol 1-allylimidazole. After reacting at room temperature for 3h, filter to obtain a blue solution. Transfer the solution to a test tube. Move the test tube into a sealed container filled with ether reagent for diffusion. After 10 days, the crystal of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 is obtained, and the yield is 63%.

[0035] Example 2

[0036] Take 0.5mmol CoCl2 and dissolve it in 10ml anhydrous acetonitrile, then add 1mmol sodium dicyanamide, stir for 30min, and then add 2.5mmol 1-allylimidazole. React at room temperature for 3h, filter to obtain a blue filtrate, and transfer the filtrate to a test tube. Finally, move the test tube into a sealed container filled with ether reagent for diffusion. After 7 days, the crystal of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 is obtained, and the yield is 60%.

[0037] Example 3

[0038] Take 0.5mmol CoCl2 and dissolve it in 15ml anhydrous acetonitrile, then add 1mmol sodium dicyanamide, stir for 30min, and then add 2.0mmol 1-allylimidazole. After reacting at room temperature for 3h, filter to obtain a blue solution. Transfer the solution to a test tube, and move the test tube into a sealed container filled with ether reagent for diffusion. After 13 days, the crystal of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 is obtained, and the yield is 61%.

[0039] The mononuclear cobalt complex Co(bim)4[N(CN)2]2 prepared in Example 1 was used as a sample to carry out the following determination:

[0040] (1) Crystal structure determination

[0041] Single crystals of appropriate size were selected under a microscope, and the structure was tested at room temperature on a Bruker SMARTApex IICCD single crystal instrument using a graphite-monochromatized molybdenum target. The APEXII program was used to collect data and determine the unit cell. The structural data were normalized and absorption corrected using the SAINT and SADABS programs. The SHELXTL-97 program was used for structural analysis. All non-hydrogen atomic coordinates were obtained by the difference Fourier synthesis method, and the atomic coordinates and anisotropic temperature factors were corrected using the full matrix least squares method, and all hydrogen atoms were hydrogenated using theory. Figure 1The structure of the mononuclear cobalt complex Co(bim)4[N(CN)2]2 is shown in Table 2. The crystallographic data and the 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: Coordination bond length and bond angle data of 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 with cobalt ions in a monodentate coordination mode. The central cobalt ion adopts a [CoN6] coordination mode, wherein four nitrogen atoms are derived from four different 1-allylimidazoles, and the other two nitrogen atoms are derived from two different dicyanamides, thereby forming a distorted octahedral coordination configuration, which is calculated by 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) Characterization of magnetic properties: The complex obtained in Example 1 was analyzed by elemental analysis to obtain the following elemental analysis results: Elemental analysis (%): calculated values: C 53.93, H 5.17, N 31.45; experimental values: C 53.91, H 5.19, N 31.44. The elemental analysis test values ​​are consistent with the chemical formula shown by the single crystal test data.

[0051] (3) Magnetic properties characterization:

[0052] The magnetic measurement uses the superconducting quantum interference device Quantum Design MPMS SQUID VSM magnetic measurement system. The test temperature of DC magnetic susceptibility is 2.0~300K, and the magnetic field is 1000Oe. The test temperature of magnetization intensity is 2K, 3K and 5K, and the magnetic field is 0~7T. The frequency range of AC magnetic susceptibility is 1~1000Hz, the temperature range is 2.0~6.0K, and the external DC magnetic field is 1000Oe.

[0053] like Figure 2 As shown in Figure 2, 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, with the increase of magnetic field intensity, 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 1000Oe, 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 show slow magnetic relaxation properties under an external magnetic field, and therefore can 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, and 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, and 1-allylimidazole is added after stirring 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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