Monosubstituierte Derivate des Halbsandwich-Komplexes Cp*Ta(CO)4 - Vergleich mit den analogen Vanadiumverbindungen Cp*V(CO)3L und Röntgenstrukturanalyse des y-Picolin-Komplexes Cp*V(CO)3(NC5H4-Me(4))

The photo-induced substitution of a CO ligand in Cp*Ta(CO)4 (1) has been used to pre­ pare a series of Cp*Ta(CO)3L (2) complexes, in which the two-electron ligand L includes, e.g., isonitriles, sulfanes, cyclic ethers, phosphanes and pyridines. The complexes (2a-y) were characterized by their v(CO) frequencies and their ’H and 13C NMR spectra, and were compared if possible with the corresponding vanadium complex, Cp*V(CO)4 (3) and its derivatives, Cp*V(CO)3L (4). The molecular structure of the 4-picoline complex Cp*V(CO)3(NC5H4-Me(4)) (4r) has been determined by X-ray crystal structure analysis.