When solvent becomes reactant: a study of 6-aminothiocytosine derivatives

Acta Crystallogr C Struct Chem. 2020 Oct 1;76(Pt 10):992-999. doi: 10.1107/S2053229620012504. Epub 2020 Sep 29.

Abstract

The dissolution of 6-aminothiocytosine in common solvents (such as methanol, dimethyl sulfoxide and dichloromethane) under alkaline conditions is shown to afford new compounds with a 6-aminothiocytosine skeleton: 2,2'-disulfanediylbis(pyrimidine-4,6-diamine) (1), C8H10N8S2, 2,2'-[methanediylbis(sulfanediyl)]bis(pyrimidine-4,6-diamine) (2), C9H12N8S2, 2-[(methoxymethyl)sulfanyl]pyrimidine-4,6-diamine (3), C6H10N4OS, and poly[(μ-4,6-diaminopyrimidine-2-sulfinato)potassium(I)] (4), [K(C4H5N4O2S)]n. The crystal architectures of these compounds are found to be strongly influenced by extensive hydrogen-bond networks, although some individual features are also observed. Specifically, 1 is characterized by very short C-H...N hydrogen bonds, 2 features apparently weak and long C-H...π, C-H...S and π-π contacts as the greatest contributors to stabilization energy, while 3 contains ribbons of molecules formed by centrosymmetric dimers of two types, and 4 is characterized by layers with principal structural units comprising distorted six-molecule rings. The intermolecular interactions in 1-4 are characterized in terms of their geometry, topology and energy, and the corresponding results are confirmed and visualized using Hirshfeld surface analysis.

Keywords: 6-aminothiocytosine derivative; DAPMT; crystal structure; hydrogen bonding; reactive solvent; solvent effect.