Complexes hétéronucléaires Cp2MM′(Cp)(CO)3 (M  Nb, Ta; M′  Mo, W) avec groupes carbonyles pontants et semi-pontants: synthèse et comportement dynamique

Abstract Heteronuclear structures Cp 2 MM′(Cp)(CO) 3 (M  Nb, Ta; M′  Mo, W) are obtained by heating Cp 2 MH 3 (M  Nb, Ta) with Cp 2 M′ 2 (CO) 6 (M′  Mo, W) or starting from Cp 2 M(CO)H and Cp 2 M′ 2 (CO) 4 . These heterobimetallic complexes show three CO coordination modes: terminal, semi-bridging and bridging. The two cyclopentadienyl groups of the Cp 2 M moiety are anisochronous owing to molecular rigidity; rotation barriers around the MM′ bond have been estimated and are greatest with tantalum derivatives.