CONFORMATIONAL POLYMORPHS OF ACETONE TOSYLHYDRAZONE

Two polymorphs of 2-isopropylidene-1-(p-toluenesulfono)hydrazide (acet one tosylhydrazone, C10H14N2O2S) are described. Both forms, one tricli nic and the other monoclinic, are obtained upon crystallization from t he same solvent. These are conformational polymorphs; the aryl ring ec lipses one of the S-O bonds in the triclinic structure [O1-S1-C4-C5 = -0.9 (2)degrees] but not in the monoclinic structure [O1-S1-C4-C5 = -1 4.2 (2)degrees]. In spite of the conformational difference, molecules of the two polymorphs engage in similar intermolecular hydrogen-bondin g contacts. Calculations using Cerius(2) [Molecular Simulations (1996) . Cerius(2) Program. MS, 9685 Scranton Road, San Diego, CA 92121-3752, USA] indicate that the triclinic form is more stable than the monocli nic form by approximately 1 kcal. Subtle conformational differences of the type described here may be expected to present a challenge. to th e successful prediction of crystal structures.