Isocyanate, urea and amide complexes from the reactions of organic azides with low oxidation state complexes of transition metals

The reactions of organic azides RN3 (R = p-CH3C6H4SO2, p-CH3C6H4CO, C6H5CO, 2-carbonylfuran) with Ru(CO)3(PPh3)2 in benzene have been studied. Isocyanate, Ru(CO)2(PPh3)2(RNCO), urea, Ru(CO)2(PPh3)2(RNCONR) or amide, Ru(CO)2(PPh3)2(NHR)2, derivatives were obtained, depending on the reaction conditions and on the nature of R. The urea complex (R = p-CH3C6H4SO2) was also obtained by the oxidative addition of N,N′-ditoluene-p-sulphonyl urea or toluene-p-sulphonyl isocyanate to Ru(CO)3(PPh3)2. The isocyanate derivative with R = C6H5CO was found to be protonated by fluoboric acid to give the corresponding carbamoyl complex, [Ru(CO)2(PPh3)2(CONHR)]+BF4- which on treatment with LiCl gave the non-ionic derivative, [Ru(CO)(PPh3)2(CONHR)Cl]n. Analogous reactions were studied with the complexes Ru3(CO)9L3 (L = CO, PPh3), but the only characterizable product was the monomeric Ru(CO)2L2(RNCONR) (L = PPh3, R = p-CH3C6H4SO2). Attempted cycloaddition reactions in benzene of the azides to coordinated ligands L other than carbon monoxide, such as CS2, PhNCS, alkenes, in the complexes Pt(PPh3)2L or SO2 in Pt(PPh3)3SO2 were unsuccesful. Only in protic solvents was a clean reaction observed (L = CH2CHCN), leading to the known complex Pt(PPh3)2(N3)(NHR) (R = p-CH3C6H4SO2). Similarly, the complexes Pd(LL)(dba) (LL = 2,2′-bipyridyl, o-phenanthroline, dba = dibenzylideneacetone), on treatment with RN3 in ethanol gave the new amide derivatives, Pd(LL)(X)(NHR), (X = NHR, R = p-CH3C6H4SO2; X = N3, R = p-CH3C6H4CO).