Polynuclear Isocyanides Complexes of Rhenium

The kinetics of the decomposition of MeTl(OA)2 in C5D5N, and in the presence of equimolar amounts of C5D5N in CD3OD, have been studied by 1H NMR-spectroscopy. Products in pyridine are TlOAc and N-methylpyridinium acetate, as well as MeOac and decomposition products of N-methylpyridinium acetate; the reaction order changes during decomposition. In methanol MeTl(OAc)2 and pyridine give>90 mole-% N-methylpyridinium acetate and <10 mole-% MeOAc; the reaction follows in good approximation a second order law. On the basis of data calculated from the derived rate equation and experimental data, a bimolecular mechanism, and, as rate determining ste, an SN 2-attack of pyridine and OAc- at the Tl-bonded CH3-group of MeTlOAc+ is formulated. Because of the less nucleophilic character of OAc- in comparison with pyridine, MeOAc is formed only in minor amounts.