PARAMAGNETIC SPECIES IN THE SPONTANEOUS AND PHOTOINDUCED REACTION OF NITROCOMPOUNDS WITH BU4NBH4

Several nitroalkanes and nitroarenes have been reacted with BH4NBu4 either in THF on in benzene. Nitroalkanes do not give any spontaneous reaction, but upon photolysis afford the hitherto undetected boroxy nitroxides in benzene and the tetrahydrofuranyloxy nitroxide in THF. !,4-dinitrobenzene reacted spontaneously with the borohydride either in THF or in benzene to give the corresponding radical anion via a single electron transfer (SET) process; nitrobenzene reacted spontaneously only in THF, while in benzene the formation of the radical anion only occurred upon photolysis. !,3-dinitro and 1,3,5-trinitrobenzene, despite tyheir small E(1/2) values, do not give electron transfer, but undergo addition by a hydride anion to give Meisenheimer complexes; on the other hand, 2,4,6-tri-tert-butyl nitrobenzene, which has a reduction potential more negative than the other nitroarenes, behaves more like nitroalkanes.