| Abstract
| - The reaction of NO-Fe(TPP) with low pressures of NO gas proceeds through three distincttransformations, the first of which we suggest is the formation of an N−N-coupled, (NO)2 adduct intermediate.The subsequent formation of NO(NO2)Fe(TPP), which under these conditions readily loses NO, suggests thatit is formed by addition of free NO2 to the starting nitrosyl. A mechanism is proposed which implies that theaddition of a competitive O atom acceptor would lead to catalytic production of N2O. In agreement with theproposed mechanism, the formation of N2O is decoupled from the formation of the nitrite by using PPh3 asthe competitive acceptor. The mechanism of O atom transfer was examined by cross-labeling experiments,which show that both O atoms in the intermediate are equivalent, even under catalytic conditions. The formationof an intermediate was confirmed by IR spectroscopy of the heterogeneous reaction of an NO-Fe(TPP) filmwith gaseous NO, in which transient, isotope-sensitive ν(ΝΟ) bands are seen prior to NO(NO2)Fe(TPP)formation. Mixed 14N/15N label experiments demonstrate coupling between the two bound nitrosyls in thetransient species.
|
