The Crystal and Molecular Structure of Benzaldehyde Thiosemicarbazone

Department of Chemistry, Kurukshetra University, Kuruhhetra-136 119

Manuscript received 15 February 1996, revised 25 September 1996, accepted 19 December 1996

Benzaldehyde thiosemicarbazone forms rectangular plate -like orthorhombic crystals elongated parallel to b-axis with unit cell dimensions of a= 20.989(5), b = 6.186(1), c = 7.659(2) Å The space group is P2₁2₁2₁ and there are four molecules per unit cell. D_m is 1.18(2) g cm^-3 and D_c is 1.16 g cm^-3. The structure has been solved by direct methods and refined by least-squares to an R index of 0.05 for 1125 observed reflections with a diffractometer. The structure comprises one molecule per asymmetric unit. The benzene ring and the thiosemicarbazide group are individually planar, but the thiosemicarbazide group is tilted by ~11° to the mean benzene plane. The C-S bond distance 1.686 Å is similar to that found in other thiosemicarbazones. The N-N bond length of 1.389 Å is interpreted in terms of the conjugation of the side-chain with the benzene ring.