Nature of the active silane alcoholysis catalyst in the Ru<i>_w</i>Cl<i>_x</i>(CO)<i>_y</i>(PMe₃)<i>_z</i> (<i>w</i>, <i>x</i>, <i>y</i>, <i>z</i> = 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 Ru 2 (µ-Cl) 2 Cl 2 (CO) 4 (PMe 3 ) 2 (1) forms an active silane alcoholysis complex in the polar solvent N,N-dimethylamino-acetamide (DMA). The dynamic behaviour of 1 in DMF-d 7 solution has been investigated by variable temperature (VT) 1 H NMR. The solid state structures of 1 and cis,cis,trans-RuCl 2 (CO) 2 (PMe 3 ) 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(PPh 3 ) 3 , PdX 2 (X = Cl - , OAc - ), and cis,cis,trans-[IrH 2 S 2 L 2 ]SbF 6 (L = PPh 3 , 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.