Quantum chemical study of nitrosonium complexes of the 9-methyladenine-1-methylthymine complementary pair. Structure and dynamics

Abstract

Nitrosonium complexes of 1-methylthymine and 9-methyladenine, as well as of their complementary pair, have been studied at the RI-MP2/L1 level of theory. The addition of nitrosonium ion to molecules of these compounds or their H-bonded pair gives a set of nitrosonium complexes of different types (1η-3η). The complex with the NO + ion coordinated to N 3 of the adenine moiety corresponds to the global minimum on the potential energy surface. The gain in energy in the interaction of nitrosonium complexes of 1-methylthymine and 9-methyladenine with 9-methyladenine and 1-methylthymine, respectively, is larger than in the formation of a neutral 9-methyladenine-1-methylthymine couple. Specific structural features and dynamics of the nitrosonium complexes are discussed.