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]

The interaction between bis(4-methylpyrazol-1-yl)methane or bis(3,4,5-trime thylpyrazol-1-yl)methane and several MX2 salts (M = Mn, Fe, Co, Ni or Cu; X = Cl; M = Mn, Co, Ni or Cu, X = NO3; M = Zn, X = Br) gives 1:1 and 2:1 add ucts depending on counter-ion, molar ratio of reagents and solvent of react ion employed. Structural conclusions are drawn from IR, far-IR, UV, magneti c susceptibility and conductivity data. In the crystal structure of the tit le compound the zinc atom is found in a strongly distorted tetrahedral coor dination [N-Zn-N: 92.2(6); Br-Zn-Br: 119.1(1)degrees]. The Zn-N [2.075(19) and 2.078(15) Angstrom] and Zn-Br [2.350(3) and 2.372(3) Angstrom] bond dis tances are longer than those reported for related compounds owing to steric hindrance of the N-2-donor. (C) 1998 Elsevier Science Ltd. All rights rese rved.