Siliciumhaltige Carben-Komplexe X. Ethoxy- und Ethylthio(Triphenylsilyl)keten aus Carben-Komplexen (CO)5WC(XEt)SiPh3 (X=O,S)

Article abstract of DOI:10.1016/0022-328X(88)89026-0

The carbene complex (CO)5WC(SEt)SiPh3 (1) decomposes at 0 deg C to give the isolable ketene Ph3Si(EtS)C=C=O (3) and a metal complex (4), in which 3 is coordinated to a (CO)5W fragment via its sulfur atom.The ketene ligand in 4 can be cleaved from the metal by tetraethylammonium bromide or by CO.The much more reactive ketene Ph3Si(EtO)C=C=O (7) is formed on treatment of (CO)5WC(OEt)SiPh3 (2) with 50 atm CO at room temperature.The ketenes 3 and 7 are readily hydrolized to give the corresponding acids Ph3Si(EtX)CHCOOH (5:X=S; 9:X=O).The anhydride 2O (8), which is obtained from 7 after addition of an appropriate amount of water, and the ketene 3 have been characterized by X-ray crystallography.Upon in situ reaction of 7 with 2,3-dihydrofuran the <2+2>-cycloaddition product 10 is formed in high yields.Two isomers, with the Ph3Si group in endo or exo position, are found in a 16/2 ratio.