Organoimido and organodi-imido vanadium complexes

Abstract

Reactions of the p-tolylimido vanadium(V) complex [V(NTol)Cl 3], 1, with sodium dithiocarbamate salts Na[S 2CNR 2] yield an homologous series of organoimido vanadium(V) dithiocarbamate systems [TolNV(S 2CNR 2) x Cl (3− x )] [ x = 1:REt (2 a), Me (3 b); x = 3: REt (4 a), Me (4 b)]; the electronic and 51V NMR spectra of these complexes are described. Zn reduction of complexes 3 affords impure products whose ESR spectra are consistent with the presence of the V(IV) systems [V(NTol) (S 2CNR 2) 2], 5. Reaction of VOCl 3 with 0.5 equiv. of p-OCNC 6H 4-NCO yields the p-phenylenediimido complex [Cl 3VNC 6H 4NVCl 3], 6. Dissolution of 6 in THF produces an adduct [(THF) 3Cl 3VNC 6H 4NVCl 3(THF) 3], 7, whose THF ligands are weakly bound. VOCl 3 reacts with an equimolar amount of p-OCNC 6H 4NCO to produce the mononuclear complex p-[Cl 3VNC 6H 4NCO], 8. The reaction of 8 with OWCl 4 in refluxing toluene affords an insoluble product analyzing as the expected heterobinuclear system [Cl 3VNC 6H 4NWCl 4], 9, but treatment of this product with THF yields a mixture shown by 1H NMR to contain both 7 and its ditungsten analogue [(THF)Cl 4WNC 6H 4NWCl 4(THF)], indicating that an unusual intermetallic exchange of imido ligands has occurred. The chloride ligands of 6 can be substituted by [S 2CNEt 2] or [O t Bu] anions to afford [(Et 2NCS 2) 3VNC 6H 4NV(S 2CNEt 2) 3], 11, and [( t BuO) 3 V NC 6 H 4 N V(O t Bu) 3] ,, 12, respectively.