TRANSFORMATION OF A METHYLENEAMIDE LIGAND AT MOLYBDENUM - ELECTROCHEMICAL OXIDATION TO A CYANIDE, REACTIONS WITH ELEMENTAL OXYGEN, SULFUR OR SELENIUM AND X-RAY CRYSTAL-STRUCTURES OF TRANS-[MO(CN)CL(DPPE)2].MEOH AND TRANS-[MO(NCS)CL(DPPE)2] TRANS-BIS[1,2-BIS(DIPHENYLPHOSPHINO)ETHANE-KAPPA-2P,P']CHLOROCYANO-MOLYBDENUM(II)-METHANOL (1/1) AND BIS[1,2-BIS(DIPHENYLPHOSPHINO)-ETHANE-K2P,P']CHLORO(THIOCYANATE-KAPPA-N)MOLYBDENUM(II) ELECTROREDUCTION OF THE CYANIDE TO AN AMINOCARBYNE, TRANS-[MO(CNH2)CL(DPPE)2] (DPPE = PH2PCH2CH2PPH2)

Deprotonation of the methylimide trans-[Mo(NMe)Cl(dppe)2]+ (dppe = Ph2PCH2CH2PPH2) gives the reactive methyleneamide trans-[Mo(NCH2)Cl(dppe)2] A; oxidation of A at a platinum anode or by iodine gives trans-[Mo(CN)Cl(dppe)2] B, the structure of which has been determined by X-ray crystallography. Carbon-13 labelling studies suggest that the rearrangement of the MoNC framework to MoCN is intramolecular. Compound A reacts with chalcogens to give heterocumulene complexes trans-[Mo(NCX)Cl(dppe)2] C (X = O, S or Se), and the X-ray crystal structure of the sulphur derivative shows that the NCS ligand is N-bonded as an isothiocyanate. The electrochemistry of compound B is extensive: reduction under N2 gives trans-[Mo(N2)(CN)(dppe)2]- and in the presence of phenol affords the isolable aminocarbyne trans-[Mo(CNH2)Cl(dppe)2].