ETA(7)-CYCLOHEPTATRIENYLCARBONYLVANADIUM COMPLEXES WITH MONOFUNCTIONAL AND BIFUNCTIONAL PHOSPHANE LIGANDS - A V-51 NMR SPECTROSCOPIC STUDY

The photo-induced reaction of (eta7-C7H7)V(CO)3 with phosphanes (L) leads generally to monosubstituted derivatives of the type (eta7-C7H7)V(CO)2(L) (1) (L = PMe3 (1a), PPh3 (1b), PnBu3 (1c), P(OMe)3 (1d), P(OEt)3 (1e), P(OMe)2(OSiMe3) (1f) and P(NMe2)3 (1g)). The synthesis may be conducted either directly under irradiation in tetrahydrofuran solution or indirectly via the photo-generated, labile acetonitrile complex (eta7-C7H7)V(CO)2(NCMe) which reacts with L in a dark reaction under mild conditions. Disubstituted derivatives of the type (eta7-C7H7)V(CO)(L)2 (2) (L = PMe3 (2a) and P(OMe)3 (2d)) are only formed with small phosphane ligands. The chiral Complex (eta7-C7H7)V(CO)(PMe3)]P(OMe)3) (2a/d) can be generated photolytically from 1d and PMe3 and identified in solution. Binuclear complexes [(eta7-C7H7)V(CO)2]2(mu2-L-L) (3) (L-L = Ph2PC=CPPh2 (3h), cis-Ph2PCH=CHPPh2 (3i) and MePCH2CH2PMe2 (3j)) as well as chelate complexes (eta7-C7H7)V(CO)(L-L) (4) (L-L = cis-Ph2PCH=CHPPh2 (4i) and Me2PCH2CH2PMe2 (4j)) can be obtained by photolysis of (eta7-C7H7)V(CO)3 in the presence of bifunctional phosphanes L-L. For the characterisation of the new complexes, the combination of V-51 and P-31 NMR spectroscopy has been shown to be particularly useful.