Luminescent gold(I) and copper(I) phosphane complexes containing the 4-nitrophenylthiolate ligand: Observation of π→π* charge-transfer emission

Abstract

Gold(I) and copper(I) phosphane complexes containing the 4-nitrophenylthiolate ligand, namely [(PCy3)Au(SC6H 4NO2-4)] (1) (PCy3 = tricyclohexylphosphane), [Au2(μ-dcpm)-(SC6H4NO2-4) 2] (2) [dcpm = bis(dicyclohexylphosphanyl)-methane], [Au 2(μ-dppm)(SC6H4NO2-4) 2] (3) [dppm = bis(diphenylphosphanyl) methane], and [(μ2-SC6H4NO2-4) 2(μ3-SC6H4NO2-4) 2(CuPPh3)4] (4), were prepared and characterized by X-ray crystal analysis. All of these complexes show an intense absorption band with λmax at 396-409 nm attributed to the intraligand (IL) π(S)→π*(C6H4NO 2-4) charge-transfer transition. The assignment is supported by the results of DFT and TDDFT calculations on the model complexes [PH 3Au(SC6H4NO2-4)] and [(μ2-SC6H4NO2-4) 2(μ3-SC6H4NO2-4) 2(CuPH3)4]. The emissions of solid samples and glassy solutions (methanol/ethanol, 1:4, v/v) of 1-4 at 77 K are assigned to the [π(S)→π*(C6H4NO2-4)] charge-transfer excited state. Metallophilic interactions are not observed in both solid state and solutions of complexes 1-3. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.