Isocyanate versus isothiocyanate insertion into alkoxo and imido ligands

Room-temperature treatment of Mo(NAr)2(OBut)21(Ar = 2,6-Pri2C6H3) with excess PhNCO in pentane affords the bis(carbamate) complex, Mo(NAr)2[NPhC(O)OBut]22, as a result of isocyanate insertion into both of the metal–alkoxide bonds; contrastingly 1 adds PhNCS to one metal–nitrogen bond to give the thioureato-N,N′ complex Mo(NAr)[NPhC(S)NAr](OBut)23.