Acta Crystallographica, Section C: Crystal Structure Communications 2008-10-01

Two thiosemicarbazones derived from salicylaldehyde: very specific hydrogen-bonding interactions of the N-H...S=C type.

Mirta Rubcić, Ivica Dilović, Marina Cindrić, Dubravka Matković-Calogović

Index: Acta Crystallogr. C 64(Pt 10) , o570-3, (2008)

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Abstract

The molecular structures of two salicylaldehyde thiosemicarbazone derivatives, namely salicylaldehyde 4-phenylthiosemicarbazone, C(14)H(13)N(3)OS, (I), and 4-methoxysalicylaldehyde 4-phenylthiosemicarbazone, C(15)H(15)N(3)O(2)S, (II), both of potential pharmacological interest, are found in the keto (thione) tautomeric form. The first compound represents a second triclinic polymorph of composition beta-C(14)H(13)N(3)OS. Although both polymorphs crystallize in the same space group (P1), the alpha-polymorph [Seena, Kurup & Suresh (2008). J. Chem. Crystallogr. 38, 93-96] differs from the beta form in its unit-cell volume at 293 K. The molecules in the crystal structures of (I) and (II) are linked into centrosymmetric R(2)(2)(8) dimers by hydrogen bonds of the N-H...S=C type. These dimers are connected through pi-pi stacking and T-shaped C-H...pi interactions into three-dimensional networks.