Microsecond UV flash photolysis of Co 2(CO) 8 in solution: Wavelength dependence of the Co(CO) 4/Co 2(CO) 7 branching ratio

Abstract

Time-resolved step-scan Fourier transform infrared spectroscopy is used to observe, for the first time in room-temperature solution, the coordinatively unsaturated species Co(CO) 4 and Co 2(CO) 7, the products of UV flash photolysis of Co 2(CO) 8. There appears to be minimal interaction between Co(CO) 4 and the solvent, but significant solvation of ‘Co 2(CO) 7’. The Co 2(CO) 7:Co(CO) 4 ratio depends very strongly on the photolysis wavelength: photolysis in n-heptane at 266 nm or 308 nm produces [Co 2(CO) 7] and [Co(CO) 4] in a ratio of ∼2:1, but the ratio following 355 nm photolysis is ∼1:4. The wavelength dependence of the branching ratio is discussed in terms of the electronic spectrum of Co 2(CO) 8.