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 Ph3GeCHPz2W(CO)4 and Me3SiCHPz2W(CO)4 (Pz=3,5-dimethylpyrazole)

A series of new bis(pyrazol-1-yl)methane ligands with organogermyl and organosilyl groups on the methine carbon, MCHPz2 (M=Ph3Ge, PhMe2Si, iPr3Si or Me3Si; 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 MCHPz2W(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 Ph3GeCHPz2W(CO)4 and Me3SiCHPz2W(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.