INTERACTION OF CARBON-DIOXIDE WITH ACETYLENE COMPLEXES OF TITANOCENE CP2TI(RC2R) (R = PH, SIME3). SYNTHESIS AND STRUCTURE OF BINUCLEAR SIGMA-ALKENYLCARBOXYLATE COMPLEXES OF TITANIUM(III) CP2TIC(R)=C(R)COOTICP2AND UNEXPECTED TRANSFORMATION OF THESE COMPLEXES INTO TITANAFURANONE METALLACYCLES UNDER THE ACTION OF AIR OXYGEN

It has been shown that carbon dioxide reacts with acetylene complexes of titanocene Cp2Ti(RC2R) (R = Ph, SiMe3) at room temperature and atmo spheric pressure to form binuclear o-alkenylcarboxylate complexes of t rivalent titanium Cp2TiC(R)=C(R)-COOTiCp2 containing two fused chelate cycles and a tricoordinated oxygen atom. The interaction of these bin uclear carboxylate complexes with air oxygen at 20 degrees C results i n rapid formation of titanafuranone metallacycles Cp-2 TiC(R)=C(R)-C(O )-O. X-ray diffraction studies of complexes Cp2TiC(SiMe3)=C(SiMe3)-COO TiCp2 and Cp-2 TiC(Ph)=C(Ph)-C(O)-O have been carried out. (C) 1997 El sevier Science S.A.