Coordination compounds derived from first-row transition metal salts. Synthesis, analytical, spectroscopic and structural characterization. Crystal structure of [{bis(3,4,5-trimethylpyrazol- 1-yl)methane}ZnBr2]

Abstract The interaction between bis(4-methylpyrazol-1-yl)methane or bis(3,4,5-trimethylpyrazol-1-yl)methane and several MX 2 salts (M=Mn, Fe, Co, Ni or Cu; X=Cl; M=Mn, Co, Ni or Cu, X=NO 3 ; M=Zn, X=Br) gives 1:1 and 2:1 adducts depending on counter-ion, molar ratio of reagents and solvent of reaction employed. Structural conclusions are drawn from IR, far-IR, UV, magnetic susceptibility and conductivity data. In the crystal structure of the title compound the zinc atom is found in a strongly distorted tetrahedral coordination [N–Zn–N: 92.2(6); Br–Zn–Br: 119.1(1)°]. The Zn–N [2.075(19) and 2.078(15) A] and Zn–Br [2.350(3) and 2.372(3) A] bond distances are longer than those reported for related compounds owing to steric hindrance of the N 2 -donor.