Time-resolved infrared study of reactive species produced by flash photolysis of the hydroformylation catalyst precursor Co-2(CO)(6)(PMePh2)(2)

摘要

Flash photolysis with time-resolved infrared (TRIR) spectroscopy was used to elucidate the photochemical reactivity of the hydroformylation catalyst precursor Co-2(CO)(6)(PMePh2)(2). Depending on reaction conditions, the net products of photolysis varied significantly. A model is presented that accounts for the net reactivity with two initial photoproducts, the 17-electron species Co(CO)(3)(PMePh2) and the coordinatively unsaturated dimer CO2(Co)(5)(PMePh2)(2). No evidence was found for photochemical formation of CO2(CO)(6)(PMePh2). Time-resolved spectroscopic studies allowed for the direct observation of transient species and for kinetics studies of certain reactions; for example, the reactions Of CO(CO)(3)PMePh2 with CO and with PMePh2 gave the respective rate constants 1.5 x 10(5) and 1.2 x 10(7) M-1 s(-1), while the analogous reactions with CO2(CO)(5)(PMePh2)(2) gave the rate constants of 2.6 x 10(6) M-1 S-1 and 3.9 X 10(7) M-1 s(-1). (c) 2006 Elsevier B.V. All rights reserved.