Chiral Octahedral Bimetallic Assemblies with Δ-TRISPHAT as Counter Anion: Design, Anion Metathesis, and Cp☆Ir as a Probe for Chiral Recognition

The chiral octahedral bimetallic assemblies [(bpy)(2)Ru(o-L-Ir)][CF3SO3](2) (2), [(ppy)(2)Rh(o-L-Ir)][NO3] (7) and [(ppy)(2)Ir(o-L-Ir)][NO3] (8) featuring chelating organometallic linker [Cp*Ir(eta(4)-o-benzoquinone)] (o-LIr) have been prepared and fully characterized. Anion metathesis following a convenient procedure allowed the preparation of the related diastereomers [Delta-(bpy)(2)Ru(o-L-Ir)][Delta-TRISPHAT](2) (2a) and [Delta-(bpy)(2)Ru (o-L-Ir)][D-TRISPHAT](2) (2b) as well as the octahedral rhodium [(Delta, Delta)-(ppy)(2)Rh (o-L-Ir)][D-TRISPHAT] (7a, 7b) and iridium [(D, L)-(ppy)(2)Ir(o-L-Ir)][Delta-TRISPHAT] (8a, 8b) bimetallic assemblies. H-1 NMR studies in solution carried out on these compounds showed different behavior. For instance, the rhodium and iridium compounds exhibited weak chiral recognition in contrast the ruthenium compounds allowed facile differentiation between the two diastereomers suggesting that chiral recognition occurs between the enantiopure anion and the cationic part of the molecule. Chirality 22: 889-895, 2010. (C) 2010 Wiley-Liss, Inc.