The NO(4Π)-catalysed geometric isomerization of the 2-butenes

Nitric Oxide Catalysis of Diazene E/Z Isomerization

“…The adventitious oxygenation of NO to NO 2 has led to some confusion as to which is the more active cis–trans catalyst, and it is noteworthy that for those working in carefully controlled, low-concentration experiments, NO is reported as the catalyst for gas-phase experiments, while researchers working in solution usually report NO 2 as the catalyst. De Maré et al have found that photosensitized NO, in its 4 Π excited state, will catalyze CTI in 2-butene but that ground state NO on its own is not catalytically active. , …”

“…De Maréet al have found that photosensitized NO, in its 4 Π excited state, will catalyze CTI in 2-butene but that ground state NO on its own is not catalytically active. 7,8 Both NO and NO 2 are stable radicals, so it is possible that they catalyze CTI by virtue of a spin exchange, 9,10 which allows access to triplet pathways, Supporting Information, Figure S1. 11,12 What makes these pathways normally inaccessible is the inability of electrons to spontaneously change spins.…”