摘要:
The titanocene dicarbonyl dication [TiCp2(CO)(2)][BPh4](2), (1) has been obtained in toluene under carbon monoxide by double protonation of TiCp4 with [(NHBu3)-Bu-n][BPh4] or by two-electron oxidation of TiCp2(CO)(2) with [FeCp2][BPh4]. Protonation reactions on ZrCp4 and HfCp4 proceed with elimination of 1 mol of cyclopentadiene independently on the ammonium salt/MCp4 molar ratio used. By this route the high electrophilic, solvent-free [ZrCp3](+) cation has been isolated and characterized by IR, H-1-NMR and elemental analysis. In the case of hafnium, the isolation has not been possible; nevertheless, in the presence of CO a rare example of a carbonyl derivative of hafnium(IV), [HfCp3(CO)][BPh4], has been isolated and characterized. (C) 2000 Elsevier Science S.A. All rights reserved.