Photochemistry of Nitrosyl Metal Complexes. Laser Photolysis Studies of Nitrosylcobalt Schiff Bases in Ethanol and Toluene in the Temperature Range 160−300 K

( N, N ‘-Disalicylideneethylenediaminato)cobalt(II), Co II salen, and ( N, N ‘-bis(1-methyl-3-oxobutylidene)ethylenediaminato)cobalt(II), Co II acacen, in both ethanol and toluene react with nitric oxide to give the nitric oxide adducts, (NO)Co II salen and (NO)Co II acacen. The laser photolysis studies revealed that (NO)Co II salen photodissociates NO to yield Co II salen with the quantum yields 1.0 ± 0.1 in ethanol and 0.6 ± 0.1 in toluene at 300 K. The transient product, Co II salen, undergoes the recombination reaction with NO to regenerate (NO)Co II salen with the rate constant 1.1 × 10 9 M -1 s -1 . The quantum yields, φ, for photodissociation of NO from (NO)Co II acacen are obtained as φ = 1.0 ± 0.1 and φ < 0.01 in toluene and ethanol, respectively. The quantum yields φ for both (NO)Co II salen and (NO)Co II acacen are found to be markedly dependent on temperature: the yield decreases with a decrease in temperature. The photodissociation mechanism of NO from (NO)Co II salen and (NO)Co II acacen is discussed on the basis of the laser photolysis studies carried out in the temperature range 160−300 K. Bunsen absorption coefficients of NO in ethanol and toluene at 300 K were determined from kinetic analysis of the recombination reaction between NO and cobalt(II) Schiff bases.