A co-crystal of heterobicyclic isomers as a product of the cyclocondensation reaction of 3,4-diaminofurazan with diethyl-2-oxosuccinate

Using single crystal XRD, it was proved that the cyclocondensation of 3,4-diaminofurazan with diethyl-2-oxosuccinate gives two products belonging to different heterocyclic systems, being structural isomers - derivatives of furazano[3,4-b]pyrazin-6-one (2) and furazano[3,4-b][1,4]diazepin-7-one (6). The simultaneous formation of compounds 2 and 6 in this reaction provokes also the generation of a third solid product, an unusual co-crystal (2)0.40(6)0.60. This is a rare example of co-crystallization of two isomers, the molecules of which occupy the same position in the crystal structure, despite the differences of the heterocyclic systems. Using SC XRD, it was proved that the cyclocondensation of 3,4-diaminofurazan with diethyl-2-oxosuccinate gives two products, being structural isomers - derivatives of furazano[3,4-b]pyrazin-6-one (2) and furazano[3,4-b][1,4]diazepin-7-one (6).