Dichlorobis(4-methylpyridine)cobalt(II)

Suppressing of slow magnetic relaxation in tetracoordinate Co(II) field-induced single-molecule magnet in hybrid material with ferromagnetic barium ferrite

The novel field-induced single-molecule magnet based on a tetracoordinate mononuclear heteroleptic Co(II) complex involving two heterocyclic benzimidazole (bzi) and two thiocyanido ligands, [Co(bzi)₂(NSC)₂], (CoL4), was prepared and thoroughly characterized. The analysis of AC susceptibility data resulted in the spin reversal energy barrier U = 14.7 cm⁻¹, which is in good agreement with theoretical prediction, U_theor. = 20.2 cm⁻¹, based on axial zero-field splitting parameter D = −10.1 cm⁻¹ fitted from DC magnetic data. Furthermore, mutual interactions between CoL4 and ferromagnetic barium ferrite BaFe₁₂O₁₉ (BaFeO) in hybrid materials resulted in suppressing of slow relaxation of magnetization in CoL4 for 1:2, 1:1 and 2:1 mass ratios of CoL4 and BaFeO despite the lack of strong magnetic interactions between two magnetic phases.

Pyridine type complexes of transition-metal halides XI.Structural, thermal and spectroscopic studies of aminopyridine complexes of cobalt(II) halides

Crystalline ternary mixed aminopyridine complexes of cobalt(II) chlorides and cobalt(II) bromides have been prepared and analysed by means of thermal (TG, DTG, DTA) methods, UV/VIS spectroscopy, magnetic measurements and X-ray powder diffraction techniques. The symmetry and cell dimensions have been calculated using TREOR 90, a trial-and-error indexing program. One of the compounds, namely the [Co(3-NH2-pyridine)4Cl2] complex has been studied also by X-ray single-crystal diffraction, yielding a propeller-shaped molecule with octahedral co-ordination, exhibiting both molecular and crystallographic inversion symmetry. Crystal data: C20H24N8Cl2Co, Mw = 506.30, triclinic (P-1) unit cell with a = 7.684(1), b = 8.582(1), c = 9.966(2) Å, α = 73.17(1), β= 69.97(1), γ = 70.33(1)°, Vc = 570.0(2) Å3 and Z = 1. The structure model was refined to R = 0.027 and wR = 0.037 for 2680 reflections with I > 3σ(I).