H–Ge bond activation by tungsten carbonyls: An experimental and theoretical study

The activation of the Ge–H bond and the formation of several hydride complexes, characterized by high-field resonances, have been detected during the 1H NMR spectroscopy monitoring of the photochemical reaction of Et3GeH and Et2GeH2 with W(CO)6 and the norbornadiene complex [W(CO)4(η4-nbd)]. The activation of the Ge–H bond of triethylgermane in the photochemical reactions of tungsten(0) complexes has been applied in the hydrogermylation of norbornadiene (nbd), which leads to the formation of endo-triethylgermylnorbornene as the major product. The complex [{W(μ-η2-H–GeEt2)(CO)4}2] has been fully characterized by NMR spectroscopy and by a single-crystal X-ray diffraction study. Evidence for the hydride ligand of the W(μ-η2-H–GeEt2) group has been provided by 1H NMR spectroscopy (δ=−9.02, 1JH–W=31Hz) and by DFT calculations. A DFT study of the structural properties and 1H NMR chemical shifts of several possible intermediate σ and hydride complexes formed during the photochemical reaction of W(CO)6 and Et2GeH2 has been performed.