Electron spin resonance studies of reduction by solvated electrons in liquid ammonia. Part 5.—Aromatic amides and thioamides
The radical-anions ArCONH–2· or -dianions ArCONH2–· of a series of ring- and N-substituted benzamides, thiobenzamides and nicotinamides have been characterized at temperatures near 200 K by electron spin resonance spectroscopy utilizing a low-temperature modification of the rapid-flow reduction technique incorporating e–amn as reductant. Most of the radicals are of the dianion type and display restricted rotation about the bond from the ring to the substituent. Assignments of coupling constants have been made by comparison with spin densities calculated by simple MO methods.