Theoretical Study of the Mechanism of Nucleophilic Addition of Oximes to trans-[PtCl4(NCCH3)2]

The mechanism of nucleophilic addition of oximes to organic nitriles coordinated to platinum was studied by ab initio methods of quantum chemistry using trans-[PtCl4(NCCH3)2] as an example. It was shown that in the absence of acidic or basic catalysis, the reaction proceeds through the formation of an orientation complex and a 4-membered cyclic transition state, whose decomposition yields the product of oxime addition to the C≡N bond. To compare and elucidate the reasons for nitrile activation in these complexes, the mechanism of hypothetical addition of formaldoxime to noncoordinated acetonitrile was studied. Calculated values of activation energy and energy effects of the reactions allow one to interpret the activation of nitriles during complexation in terms of the activated-complex model.