Phosphido-bridged Ta/Rh bimetallic complex: synthesis, structure, and catalytichydrosilylation of acetophenone

Abstract

Reaction of Cp₂TaH₃ (1) with ClPEt₂ gives the insertion product [Cp₂TaH₂(PHEt₂)]Cl (5), which upon deprotonation with LiN(SiMe₃)₂ affords the phosphido complex Cp₂TaH₂(PEt₂) (6) as the kinetic product. The latter transforms by a first-order reaction during the course of 3.5 days to the phosphine complex Cp₂TaH(PHEt₂) (7). Repetition of this insertion/deprotonation sequence gives the compounds [Cp₂Ta(PHEt₂)₂]Cl (8) and Cp₂Ta(PEt₂)(PHEt₂) (9). Reaction of the latter with 0.5[(μ-Cl)Rh(η²-C₂H₄)]₂ in the presence of LiN(SiMe₃)₂ gives the bimetallic complex Cp₂Ta(μ-PEt₂)₂Rh(η²-C₂H₄) (10), which was studied by NMR and X-ray diffraction analysis. Complex 10 catalyses the hydrosilylation of acetophenone by PhMeSiH₂.