Insertion of ethyl isocyanate and acetonitrile into the niobium-chlorine bond and the related isocyanato-nitrilo cyclization

Reactions of niobium pentachloride with ethyl isocyanate in benzene and ace tonitrile were studied. Reaction products were isolated and characterized b y elemental analysis and IR spectroscopy. The reaction in benzene yielded i nsertion products containing from one to three ligand molecules, while the reaction products in acetonitrile contain a heteromolecular chain composed of the inserted isocyanate and acetonitrile molecules in a 2 : 1 ratio. The H-1 and C-13 NMR data suggest that the decomposition of the latter product in an acetonitrile solution results in the isocyanato-nitrilo cyclization to give 1,3-diethyl-6-methyl-2,4[1H,3H]-dione-1,3,5-triazine.