Organoimido and organodi-imido vanadium complexes

Article abstract of DOI:10.1016/S0277-5387(97)00222-2

Reactions of the p-tolylimido vanadium(V) complex [V(NTol)Cl₃], 1, with sodium dithiocarbamate salts Na[S₂CNR₂] yield an homologous series of organoimido vanadium(V) dithiocarbamate systems [TolN≡V(S₂CNR₂)_xCl_(3-x)] [x = 1 : R = Et (2a), Me (2b) ; x = 2 : R = Et (3a), Me (3b) ; x = 3 : R = Et (4a), Me (4b)]; 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) (S₂CNR₂)₂], 5. Reaction of VOCl₃ with 0.5 equiv. of p-OCN - C₆H₄ - NCO yields the p-phenylenediimido complex [Cl₃V≡NC₆H₄N=VCl₃], 6. Dissolution of 6 in THF produces an adduct [(THF)₃Cl₃V≡ NC₆H₄N≡VCl₃(THF)₃], 7, whose THF ligands are weakly bound. VOCl₃ reacts with an equimolar amount of p-OCN - C₆H₄ - NCO to produce the mononuclear complex p-[Cl₃V≡NC₆H₄ - NCO], 8. The reaction of 8 with OWCl₄ in refluxing toluene affords an insoluble product analyzing as the expected heterobinuclear system [Cl₃V≡NC₆H₄N≡WCl₄], 9, but treatment of this product with THF yields a mixture shown by ¹H NMR to contain both 7 and its ditungsten analogue [(THF)Cl₄W≡NC₆H₄N≡WCl ₄(THF)], indicating that an unusual intermetallic exchange of imido ligands has occurred. The chloride ligands of 6 can be substituted by [S₂CNEt₂] or [O^tBu] anions to afford [(Et₂NCS₂)₃V≡NC₆H ₄N≡V(S₂CNEt₂)₃], 11, and [(^tBuO)₃V≡NC₆H ₄N≡V(O^tBu)₃], 12, respectively.