Synthesis of bis(pyrazol-1-yl)methanes with organogermyl and organosilyl groups on the methine carbon and their reaction with W(CO) 5(THF). X-ray crystal structures of Ph 3GeCHPz 2W(CO) 4 and Me 3SiCHPz 2W(CO) 4 (Pz=3,5-dimethylpyrazole)

Abstract

A series of new bis(pyrazol-1-yl)methane ligands with organogermyl and organosilyl groups on the methine carbon, MCHPz 2 (M=Ph 3Ge, PhMe 2Si, i Pr 3Si or Me 3Si; Pz=3,5-dimethylpyrazole or 3,4,5-trimethylpyrazole), have been prepared by the reaction of bis(pyrazol-1-yl)methyllithium with triphenylgermanium bromide and organosilyl chloride. Treatment of these ligands with W(CO) 5(THF) in refluxing THF resulted in new heterobimetallic complexes MCHPz 2W(CO) 4 as major products, accompanied by partial decomposition of ligands to yield a certain amount of PzW(CO) 5 as by-products. These new ligands and complexes have been characterized by 1H-NMR, IR and elemental analysis. The molecular structures of complexes Ph 3GeCHPz 2W(CO) 4 and Me 3SiCHPz 2W(CO) 4 (Pz=3,5-dimethylpyrazole) have been determined by X-ray structure analysis, indicating that bis(pyrazol-1-yl)methanes act as chelating bidentate ligands in these complexes, and organometallic groups lie in the axial position of the methine carbon.