Excited state properties of [Pd0(NHC)(quinone)]2 with NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and quinone=1,4-naphthoquinone

Abstract

The carbene complex [Pd-0(NHC)(quinone)](2)with NHC = 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene and quinone = 1,4-naphthoquinone shows two long-wavelength absorptions at 312 and 399 nm which are assigned to (NHC -> quinone) LLCT and (Pd-0 -> quinone) MLCT transitions. The MLCT state is not reactive, but emissive (gimel(max) = 564 nm at 77 K). At r.t., the complex undergoes a photoredox decomposition which is initiated by the LLCT state. (c) 2005 Elsevier B.V. All rights reserved.