Crystal Structures and Properties of New Mixed-Ligand Complexes of Nickel(II) Diisobutyldithiophosphinate with Imidazole and 3,5-Dimethylpyrazole

Abstract

The reaction of Ni{(i-C₄H₉)₂PS₂}₂ with imidazole and 3,5-dimethylpyrazole in ethanol gave paramagnetic (μ_ef = 3.02 and 3.11 BM) mixed-ligand complex compounds [Ni(Im)₂{(i-C₄H₉)₂PS₂}₂] (I) and [Ni(Pyr){(i-C₄H₉)₂PS₂}₂] (II). Single crystals were grown and the crystal structures of I and II were determined from X-ray diffraction data (CAD-4 diffractometer, Mo$K_\alpha$ radiation, 1483 $F_{hkl}$, R = 0.0344 for I and 2630 $F_{hkl}$, R = 0.0486 for II). The crystals are monoclinic with cell dimensions a = 12.845(2), b = 10.250(1), c = 13.431(1) Å, β = 115.89(1)°, V = 1591(1) ų, Z = 2, d _calc = 1.281 g/cm³, space group $P2_{1/c}$ (for I); a = 11.152(3), b = 12.483(2), c = 23.389(4) Å, β = 100.78(1)°, V = 3199(2) ų, Z = 4, d _calc = 1.191 g/cm³, space group $P2_{1/n}$ (for II). The structures consist of discrete monomer molecules. The coordination polyhedron of the Ni atom is a compressed octahedron NiN₂S₄ (in I) and a tetragonal pyramid NiNS₄ (in II) formed by four S atoms of the two cyclic bidentate ligands i-Bu₂ $PS_{2^\_ }$ and the N atoms of two monodentate ligands (Im molecules in trans-positions) or the N atom of the monodentate Pyr ligand in complexes I and II, respectively. The character of interaction between molecules I and II and molecular packing modes are considered. The electronic spectra of the complexes are consistent with the symmetry of chromophores found from X-ray data.