Photodissociation Spectroscopy and Photofragment Imaging to Probe Fe(Benzene) Dissociation Energies.

Tunable laser photodissociation spectroscopy measurements and photofragment imaging experiments are employed to investigate the dissociation energy of the Fe(benzene) ion-molecule complex. Additional spectroscopy measurements determine the dissociation energy of Fe(benzene). The dissociation energies for Fe(benzene) determined from the threshold for the appearance of the Fe fragment (48.4 ± 0.2 kcal/mol) and photofragment imaging (≤49.3 ± 3.2 kcal/mol) agree nicely with each other and with the value determined previously by collision-induced dissociation (49.5 ± 2.9 kcal/mol), but they are lower than the values produced by computational chemistry at the density functional theory level using different functionals recommended for transition-metal chemistry. The threshold measurement for Fe(benzene) (43.0 ± 0.2 kcal/mol) likewise agrees with the value (44.7 ± 3.8 kcal/mol) from previous collision-induced dissociation measurements.