engleski

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

The molecular structures of two salicylaldehyde thiosemicarbazone derivatives, namely salicylaldehyde 4-phenylthiosemicarbazone, C14H13N3OS, (I), and 4-methoxysalicylaldehyde 4-phenylthiosemicarbazone, C15H15N3O2S, (II), both of potential pharmacological interest, are found in the keto (thione) tautomeric form. The first compound represents a second triclinic polymorph of composition a-C14H13N3OS. Although both polymorphs crystallize in the same space group (P1), the b-polymorph differs from the a-form in its unit-cell volume at 293 K. The molecules in the crystal structures of (I) and (II) are linked into centrosymmetric R2 2(8) dimers by hydrogen bonds of the N— H...S=C type. These dimers are connected through pi– pi stacking and Tshaped C— H...pi interactions into three-dimensional networks.

thiosemicarbazones; polymorphism; hydrogen bonding

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