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 × 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 CF₂C1₂ 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).