文摘
By the method RI-MP2/L1 nitrosonium complexes were explored of 1-methylcytosine and 9-methylguanine, structural analogs of nucleotide bases cytosine and guanine, as well as of their complementary pair. The addition of a nitrosonium cation to the molecules of these compounds and to their pair leads to the formation of various types of nitrosonium complexes (1畏鈥?畏). n-Complexes with the coordination of NO+ cation to nitrogen and oxygen atoms are commonly more feasible in energy as compared with 蟺-complexes. The complex with cation NO+ coordinated at the oxygen atom of the carbonyl group and N7 atom of the guanine fragment of the pair corresponds to the global minimum on the potential energy surface. The energy gain at the interaction of nitrosonium complexes of 1-methylcytosine and 9-methylguanine with 9-methylguanine and 1-methylcytosine respectively is usually larger than at the formation of a neutral pair 1-methylcytosine-9-methylguanine.