Reaction of 4-(dimethylamino)pyridine and 1-methylimidazole, respectively, on 2-amino-4-chloro-6-hydroxypyrimidine resulted in the formation of pyrimidine-heteroarenium salts. These could be deprotonated using anion exchange resin to yield pyridinium-pyrimidinolates as model compounds for biologically highly important betainic guanines present in RNA. As proved by ESIMS, these cross-conjugated mesomeric betaines are self-complementary and form homo-intermolecular dimers.