Formation of .eta.2-iminoacyl compounds by protonation of a ketenimine ligand in bis((trimethylsilyl)cyclopentadienyl) compounds of niobium. Molecular structures of [Nb(.eta.5-C5H4SiMe3)2Cl(.eta.2(C,N)-EtPhHCCNPh)]+BF4- and [Nb(.eta.5-C5H4SiMe3)2F(.eta.2(C,N)-Ph2HCCNPh)]+BF4- | Publicación