Unexpected effect of the ring on the extent of Si⋯H interligand interactions in half-sandwich silyl hydrides of ruthenium

Abstract

This paper reports preparation of new silyl hydride complexes of ruthenium supported by the Cp/PR(3) ligand set. It is shown that the easiest and most general route to these complexes is provided by the thermal reaction of [RuCp(PR(3))(H)(3)] with hydrosilanes. Complexes [RuCp(PR(3))(H)(2)(SiMe(2)Cl)] exhibit Interligand Hypervalent Interactions (IHI) between the hydride and silyl ligands. Comparison of the X-ray structures of complexes [RuCp(PPr(i)(3))(H)(2)(SiMe(2)Cl)], [RuCp(PPhPr(i)(2))(H)(2)(SiMe(2)Cl)], and [RuCp(PPh(3))(H)(2)(SiMe(2)Cl)] shows that the IHI weakens with the decreasing electron-releasing ability of the phosphine. Comparison of the X-ray structure of [RuCp(PPh(3))(H)(2)(SiMe(2)Cl)] with the structure of the previously reported complex [RuCp*(PPh(3))(H)(2)(SiMe(2)Cl)] reveals that the lack of IHI in the latter compound is due to unfavourable steric interactions between the bulkier Cp* ring and the SiMe(2)Cl group.