Further crystallographic evidence of NH center dot center dot center dot pi(system) and CO center dot center dot center dot pi(system) interactions: The structures of bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhC=NNH-C(O)}(2)CH2] (Au = Ph, 2-C5H4N, 2-C4H3S)

In this study are reported the syntheses of three bis(dialylhydrazonecarbon yl)methylene derivatives [[ArPhC=NNH-C(O)(2)CH2] [Ar = 2-C5H4N (5), C6H5 (6 ), and 2-C4H3S (7)], obtained by condensation of corresponding hydrazones w ith carbon suboxide, C3O2. The solid-state self-assembly of these carbonyl derivatives, giving rise to polymeric and dimeric networks, is described in the formation of these structural features, in addition to N-H O=C intermo lecular hydrogen bonds, stabilizing intramolecular NH rr (systems) and inte rmolecular CO pi (systems) interactions also seem to play an important role . Solution IH-nmr data of compounds 5-7 indicate that the polymeric and dim eric structures are not maintained in solution and show the occurrence of k eto-enolic equilibria. (C) 1999 John Wiley & Sons, Inc.