AN EPR STUDY OF THE REACTION OF TETRABUTYLAMMONIUM BOROHYDRIDE WITH N-HETEROCYCLES

The reactions between tetrabutylammonium borohydride and a series of n itrogen-containing heteroaromatics bases have been investigated by ele ctron paramagnetic resonance (EPR) spectroscopy. The radical anions of the N-heterocycles, formed by a single electron-transfer process have been observed with substrates having reduction potentials higher than -1.2 V vs. SCE. With less reducible bases, the radical anions of the adducts formed by complexation by one or two borane units of the nitro gen atoms of the base were observed under photolytic conditions. This is because the complexed N-heterocycles have larger electron affinitie s than the starting base.