The lowest excited state of brightly emitting Gold(I) triphosphine complexes

Abstract

The strongly luminescent neutral gold(I) triphosphine complexes [Au(dipnc)(PPh₃)] and [Au(dppnc)(PPH₃)] with dipnc = 7,8-bis(diisopropylphosphino)-nido-carborane ([(P/Pr₂)₂ B₉H10C₂)]⁻) and dppnc = 7,8-bis(diphenyl
phosphino)-nido-carborane ([(PPh₂)₂ B₉H10C₂]⁻) are studied in a wide range of temperatures of 1.5 =< T =< 300K. Analysis of the emission decay dynamics provides detailed information about the lowest triplet state. In particular, the magnitude of zero-field splitting of the emitting state is determined to be 47 and 29 cm⁻¹ for [Au(dipnc)(PPh₃)] and [Au(dppnc)(PPh₃)], respectively. The emission decay times of the individual triplet substates lie in the range of 4 to 130 μs. The observed photophysical properties suggest that the molecular orbitals involved in the lowest electronic transitions exhibit, beside gold orbitals, considerable contributions from nonmetallic ligand orbitals. OLED or sensor application of these complexes is suggested.