Charge-transfer processes in (4-nitrobenzoate)Re(CO)(3)(azine)(2) complexes. Competitive reductions of 4-nitrobenzoate and azine in thermally and photochemically induced redox processes

摘要

The photochemically and thermally induced redox reactions of the (4-nitrobenzoate)Re(CO)(3) (azine) (azine = 1,10-phenanthroline, 2,2'-bipyridine, and (4-phenylpyridine)(2)) were investigated by flash photolysis and pulse radiolysis. Processes characterized as intramolecular charge transfers from coordinated azine radicals to the 4-nitrobenzoate ligand and vice versa were observed in a 1-100 mu s time scale by pulse radiolysis. In photochemical experiments, the conversion among metal to Ligand charge-transfer excited states, i.e., from the Re to azine to the Re to 4-nitrobenzoate charge-transfer excited stale, involves intermediates with Lives of picoseconds. A mechanism for the conversions that incorporates intraligand excited states is discussed. [References: 19]