SPONTANEOUS AND PHOTOINDUCED FORMATION OF RADICAL-ANIONS IN THE REACTION OF BOROHYDRIDES WITH UNSATURATED-COMPOUNDS

The spontaneous and photoinduced reactions of tetrabutylammonium boroh ydride, Bu4NBH4, with a number of quinones, ketones, cyano derivatives and nitrogen-containing heteroaromatic bases have been studied by mea ns of EPR spectroscopy in benzene and in ethereal solvents. In the abs ence of UV irradiation, formation of radical anions resulting from ele ctron transfer from the borohydride negative ion, BH4-, to the organic substrate has been detected with compounds having reduction potential s less negative than -1.5 V vs. SCE. With the less easily reducible co mpounds, UV irradiation leads in some cases to radical anions produced by photoinduced ET and in other cases to radical adducts of the boran e radical anion, BH3.-.