Planarity of N′-(amino-2-pyridylmethylene)-hydrazide carbodithioic acid frame and crystal structure of its methyl ester dihydrate

Abstract

The title compound exists in a dipolar form both in the solvent-free and in the dihydrate crystal. Unit cell dimensions: 23.303(5), 7.3100(10), 15.030(3) A, β = 101.78(3)∘; space group C2/c (monoclinic) with Z = 8. The molecule is flat due to extended conjugation in the central N=C(pyr)–N(3)H–N=C–S– fragment and three assisted intramolecular hydrogen bonds, one of them between the pyridine N atom (acceptor) and the N(3)H amine group as a hydrogen bond donor. As a result the molecule adopts an antiperiplanar conformation along the N–N bond and synperiplanar conformation along the neighbouring N–C bonds. Presence of two water molecules results in a very extensive network of intermolecular hydrogen bonds (eight) as compared with the crystal structure of the anhydrous compound.