Hydantoin and hydrogen-bonding patterns in hydantoin derivatives.

Abstract

The structure of hydantoin (imidazolidine-2,4-dione), C3H4N2O2, has been determined from a twinned crystal. The two carbonyl bond lengths are nearly equal, even though one of them adjoins electron-donating NH groups to either side while the other is adjacent to only one. Ab initio molecular-orbital calculations yield more negative Löwdin charge on the former than the latter. Hydantoin mol­ecules form two chains linked by N—H⋯O hydrogen bonds, from which inversion centres create a `chain of rings'. Out of 50 hydantoin moieties in 49 independent mol­ecules of hydantoin derivatives in the Cambridge Structural Database [Version 5.25; Allen (2002). Acta Cryst. B58, 380–388], five show this arrangement, six are a variant using the same O atom twice, five form a chain of edge-fused 12-membered hydrogen-bonded rings, and all but three of the remainder have one eight-membered ring and/or one chain connecting their hydantoin rings.