NO (upsilon ''=0) rotational distributions from the photodissociation of organometallic nitrosyls in the charge transfer region

The photodissociations of two metal nitrosyl compounds, Co(CO)(3)NO and Mn( CO)(4)NO, were studied at 450 nm, in the metal-to-nitrosyl charge-transfer region for both compounds. The rotational distributions of free NO in the u psilon " = 0 vibrational state were determined by laser-induced fluorescenc e excitation. A Surprisal Analysis shows that the NO population distributio ns display a dynamical bias toward lower rotation in both compounds. The si milarity between the NO rotational distributions is surprising, considering that Co(CO)(3)NO was expected to dissociate through a bent transition stat e and Mn(CO)(4)NO was not. The spin-orbit populations of the NO products (( 2)Pi (1/2) and (2)Pi (3/2)) are equally populated in both compounds, indica ting that the electronic surfaces that produce these two states are strongl y coupled at the transition state. An upper limit of the M-NO bond dissocia tion energy is estimated at 52 kcal/mol from the rotational assignments.