Inner-sphere condensation of EtNCO and MeCN through coinsertion into the Re-Cl bond

Reactions of rhenium pentachloride with ethyl isocyanate in dichloroethane and acetonitrile are the first to demonstrate the feasibility of inserting organic isocyanates and nitriles into a rhenium-halogen bond. IR spectroscopy and elemental analysis data show that the addition of one to three ethyl isocyanate molecules in dichloroethane yields ReCl₄N(Et)C(O) _n ]Cl with n = 1−3, depending on the relationship between the reactants. The reaction in acetonitrile yields a heteromolecular insertion product containing a chain of two isocyanate groups and one nitrile group attached to the same rhenium-chlorine bond: ReCl₄{N(Et)C(O)}₂N=C(Me)Cl]. When EtNCS is used instead of EtNCO, the reaction is reversible.