NO and N 2 O Release from the Trityl Diazeniumdiolate Complexes [M(O 2 N 2 CPh 3 ) 3 ] - (M = Fe, Co).

Reaction of MBr 2 with 3 equiv of [K(18-crown-6)][O 2 N 2 CPh 3 ] generates the trityl diazeniumdiolate complexes [K(18-crown-6)][M(O 2 N 2 CPh 3 ) 3 ] (M = Co, 2 ; Fe, 3 ) in good yields. Irradiation of 2 and 3 using 371 nm light led to NO formation in 10 and 1% yields (calculated assuming a maximum of 6 equiv of NO produced per complex), respectively. N 2 O was also formed during the photolysis of 2 , in 63% yield, whereas photolysis of 3 led to the formation of N 2 O, as well as Ph 3 CN( H )OCPh 3 , in 37 and 5% yields, respectively. These products are indicative of diazeniumdiolate fragmentation via both C-N and N-N bond cleavage pathways. In contrast, oxidation of complexes 2 and 3 with 1.2 equiv of [Ag(MeCN) 4 ][PF 6 ] led to N 2 O formation but no NO formation, suggesting that diazeniumdiolate fragmentation occurs exclusively via C-N bond cleavage under these conditions. While the photolytic yields of NO are modest, they represent a 10- to 100-fold increase compared to the previously reported Zn congener, suggesting that the presence of a redox-active metal center favors NO formation upon trityl diazeniumdiolate fragmentation.