lsomerisation of 2-(amino)-1-cyclopentene-1-dithiocarboxylate was observed through a five-step mechanism of intermolecular hydrogen transfer and isomerisation. Hydrogen transfer was studied at the B3LYP/6-3l+G(d,p) level of theory, both dissociative and rotational pathways were identified for the proton exchange. Three low energy conformers were identified for the title compound below the 50 kJ/mol energy limit. The optimised minimum is in good agreement with the observed solid-state structure; with an RMS overlay error of less than 0.077 angstrom. (c) 2005 Elsevier B.V. All rights reserved.