Luminescent Gold(I) and Copper(I) Phosphane Complexes Containing the 4‐Nitrophenylthiolate Ligand: Observation of π→π* Charge‐Transfer Emission

Gold(I) and copper(I) phosphane complexes containing the 4‐nitrophenylthiolate ligand, namely [(PCy 3 )Au(SC 6 H 4 NO 2 ‐4)] ( 1 ) (PCy 3 = tricyclohexylphosphane), [Au 2 (μ‐dcpm)(SC 6 H 4 NO 2 ‐4) 2 ] ( 2 ) [dcpm = bis(dicyclohexylphosphanyl)methane], [Au 2 (μ‐dppm)(SC 6 H 4 NO 2 ‐4) 2 ] ( 3 ) [dppm = bis(diphenylphosphanyl)methane], and [(μ 2 ‐SC 6 H 4 NO 2 ‐4) 2 (μ 3 ‐SC 6 H 4 NO 2 ‐4) 2 (CuPPh 3 ) 4 ] ( 4 ), were prepared and characterized by X‐ray crystal analysis. All of these complexes show an intense absorption band with λ max at 396–409 nm attributed to the intraligand (IL) π(S)→π*(C 6 H 4 NO 2 ‐4) charge‐transfer transition. The assignment is supported by the results of DFT and TDDFT calculations on the model complexes [PH 3 Au(SC 6 H 4 NO 2 ‐4)] and [(μ 2 ‐SC 6 H 4 NO 2 ‐4) 2 (μ 3 ‐SC 6 H 4 NO 2 ‐4) 2 (CuPH 3 ) 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*(C 6 H 4 NO 2 ‐4)] charge‐transfer excited state. Metallophilic interactions are not observed in both solid state and solutions of complexes 1 – 3 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)