Organosilyl derivatives of trivacant tungstophosphate of general formula α-A-[PW9O34(RSiO)3(RSi)]3- -: Synthesis and structure determination by X-ray crystallography

In the presence of (NBu4Br)-Br-n acting as phase-transfer reagent, organosilicon trichloride RSiCl3 reacts in acetonitrile with the trivacant tungstophosphate sodium salt beta-A-Na8H[PW9O34].24 H2O to give hybrid organosilyl polyoxotungstate derivatives alpha-A-[NBu(4)n](3)[PW9O34(RSiO)(3)(RSi)] (R = C2H3 (1), CH3 (2)). These compounds are characterized by X-ray crystallography. Each of the two hybrid anions consists of one alpha-A-PW9O349- framework on which is grafted by three RSiO groups through six Si-O-W 34 bridges, each of which is attached to the fourth RSi through three Si-O-Si bridges. Both hybrid anions become saturated, close cage structure and display C-3nu symmetry. (C) 2003 Elsevier Science B.V. All rights reserved.