The Bromination in Aqueous-Solution of Imidazole Coordinated to Co(NH3)5(3+)

Abstract

Bromination of imidazole coordinated to (NH3)5Co3+ (abbreviated Co) has been studied in aqueous Br- media, I = 0.1, 0.5 mol dm-3, 25.0°C; Co(4,5- Br2ImH)3+ and Co(2,4,5-Br3ImH)3+ result from treatment with Br2(aq). Co(4-BrImH )3+ has also been prepared and characterized. Rate data correspond to reaction of the conjugate base of the imidazole complex, Co(BrxIm)2+ (x = 0, 1, 2), with Br2, with successive bimolecular rate constants 6×109, 3×108 and 3.5×103 mol-1 dm3 s-1. Possible mechanisms are discussed.