BOND-DISSOCIATION ENERGIES AND KINETICS FOR THE REACTION OF W(CO)5 WITH THE UNLIKELY LIGANDS N2O AND CF2CL2

Transient infrared spectroscopy has been used to study reactions of W(CO)5, the coordinatively unsaturated tungsten carbonyl generated by 351- or 355-nm photolysis of W(CO)6. W(CO)5 is highly reactive toward CO, CF2Cl2, and N2O with bimolecular rate constants of 1.4 +/- 0.1, 1.2 +/- 0.2, and 0.5 +/- 0.1 X 10(-10) cm3 molecule-1 s-1, respectively, at 298 K. Infrared absorptions for the transiently stable W(CO)5(CF2Cl2) and W(CO)5(N2O) complexes were observed. The rate of dissociative loss of the CF2Cl2 and N2O ligands from these complexes can be determined by observation of the rate of regeneration of W(CO)6 in a reaction mixture consisting of W(CO)5L, CO, and L, where L is either CF2Cl2 or N2O. The bond dissociation energy for the loss of the chlorofluorocarbon ligand from W(CO)5(CF2Cl2) is 19.6 +/- 0.6 kcal/mol. A bond dissociation energy was estimated for the loss of the N2O ligand from W(CO)5(N2O).