Nature of the active silane alcoholysis catalyst in the RuwClx(CO)y(PMe3)z (w, x, y, z = 1 or 2) system; Ru2(µ-Cl)2Cl2(CO)4(PMe3)2 as a new catalyst for silane alcoholysis in a polar solvent

Abstract

The dimeric complex Ru2(µ-Cl)2Cl2(CO)4(PMe3)2 (1) forms an active silane alcoholysis complex in the polar solvent N,N-dimethylamino-acetamide (DMA). The dynamic behaviour of 1 in DMF-d7 solution has been investigated by variable temperature (VT) 1H NMR. The solid state structures of 1 and cis,cis,trans-RuCl2(CO)2(PMe3)2 (3) have been determined by single crystal X-ray diffractometry. Using ethylene glycol - triethylsilane as a model system, the catalytic activity of 1 in DMA is compared to that of a series of known silane alcoholysis catalysts, including RhCl(PPh3)3, PdX2 (X = Cl-, OAc-), and cis,cis,trans-[IrH2S2L2]SbF6 (L = PPh3, S = THF). Complex 3 is not an active silane alcoholysis catalyst in this solvent, but is active in nonpolar solvents. Its structure and spectroscopic signature is, however, different from that of a previously reported catalyst of the same composition.Key words: silane alcoholysis, polar solvent, ruthenium catalyst.