Photochemical and photophysical processes in fac-Re(CO) 3−(4-phenylpyridine) 3(CF 3SO 3). Steady state and flash photolysis study

Abstract

The photophysics and photochemistry of fac-Re(CO) 3(4-phenylpyridine) 3 + were investigated by monochromatic steady state and flash photolysis. Two parallel photoprocesses, photogeneration of the emissive metal-to-ligand charge transfer (MLCT) state and photoredox dissociation in [Re(CO) 3(4-phenylpyridine) 2 2+, (4-phenylpyridine −)], were observed. In the former process, the emission originating from the lower MLCT excited state is electron transfer quenched by triethanolamine (TEOA) producing an Re(CO) 3(4-phenylpyridine) 3 radical and energy transfer quenched by Cu(TIM) 2+ (TIM ≡ 2,3,9,10-tetramethyl-[14]-1,4,8,11-tetraene-N 4). The primary species Re(CO) 3(4-phenylpyridine) 2 2+ generated in the latter photoprocess undergoes several thermal changes which finally lead to dimeric products. A third photoprocess, namely the photogeneration of the [Re(CO) 3(4-phenylpyridine) 2 2+ (4-phenylpyridine −)] species, is involved in the reduction of the copper macrocycle to Cu(TIM) +.