Gold and palladium hetero-bis-NHC complexes: Characterizations, correlations, and ligand redistributions

Abstract

A series of new Au(I) hetero-bis-NHC complexes [Au(iPr 2-bimy)(NHC)]X (X = BF4, PF6, 2-6) and the hetero-tetrakis-NHC complex [Au2(iPr2-bimy) 2(μ-ditz)](BF4)2 (7) have been synthesized using the Au(I) acetato complex [Au(O2CCH3)( iPr2-bimy)] (C) as a basic metal precursor ( iPr2-bimy = 1,3-diisopropylbenzimidazolin-2-ylidene, ditz = 1,2,4-triazolidine-3,5-diylidene). The Au(III) hetero-bis-NHC complex trans-[AuCl2(iPr2-bimy)(Bn2-bimy)] BF4 (12; Bn2-bimy = 1,3-dibenzylbenzimidazolin-2-ylidene) and the hetero-tetrakis-NHC complex all-trans-[Au2Cl 4(iPr2-bimy)2(μ-ditz)](BF 4)2 (13) were obtained by oxidation of their corresponding Au(I) hetero-NHC precursors. For all Au(I) hetero-NHC complexes, the 13C carbene signals of the constant iPr2-bimy ligand are found to be highly correlated with those in Pd(II) analogues of the type trans-[PdBr2(iPr2-bimy)(NHC)], which could be applied to detect the σ-donating ability of the trans-standing NHC. In addition, an interesting ligand redistribution process was observed for some of the Au(I) hetero-bis-NHC complexes. © 2013 American Chemical Society.