The solvated electron and its interactions in hexamethylphosphoramide.

The magnetic and optical properties of sodium metal-hexamethylphosphoramide solutions are reported and their significance discussed. The interaction of the unpaired electron with its magnetic environment is probed using hydrogen-, phosphorus-, and nitrogen- nuclear magnetic resonance and electron spin resonance techniques. Consideration of the resultant data reveals that sodium- HMPA solutions contain solvated electrons whose properties resemble thise of solvated unpaired electrons contained in metal-liquid ammonia solutions. The concentration of unpaired electrons in sodium-HMPA solutions (which is not equal to the concentration of dissolved sodium metal) has been determined from static susceptibility measurements and a comparison of the magnetic properties of the electron in ammonia and in metal-HMPA solutions is made. The optical properties of the solvated electron in a variety of polar solvents are linked with those of electrons trapped within well defined sites in crystal vacancies and also with the optical absorption energies of solvated iodide ions. The use of sodium-HMPA solutions for the reduction of metal-free and transition metal phthalocyanins is also described. A parallel series of reduction experiments employing sodium-tetrahydrofuran solutions has provided valuable information concerning the influence of a strongly co-ordinating solvent, such as hexamethylphosphoramide, upon the molecular orbitals of these phthalocyanin complexes. In both series of experiments, e.s.r. spectroscopy is used to charactise the reduced species. These results and those reported by other workers are explained on the basis of a qualitative molecular orbital diagram.