THIOOXALIC ACID 2-AMIDE-1-HYDRAZIDE-2-HYDRAZONE

The results of an X-ray analysis reveal that the title compound, C2H7N 5S, has zwitterionic character (2), instead of the initially assumed f orm of a neutral tautomer (1). The bonding in (2) can be described as a resonance of several dipolar limiting structures. Their particular c ontributions to the zwitterionic resonance hybrid were estimated throu gh calculations using the HOSE model based on the observed bond length s. The two predominant resonance contributors, together with four intr amolecular hydrogen bonds, account for the almost perfect planarity of the molecules.