CATALYSIS OF PHENYL ISOCYANATE CONDENSATION TO N,N'-DIPHENYLCARBODIIMIDE VIA VANADIUM OXO AND IMIDO COMPLEXES

The following complexes catalyze the condensation of phenyl isocyanate to N,N'-diphenyl-carbodiimide: V(O)(OR)3 (R = tBu, iPr), V(NC6H4Me)-(O-tBu)3, and V(O)(acac)2 (acac = acetylacetonate). GC yields of N,N'-diphenylcarbodiimide ranged from 67 to 96%. Spectroscopic results implicate an interconversion of an oxo complex to an imido complex followed by an imido group transfer to an isocyanate to complete the catalytic cycle.