Influence of solvent and cation on the properties of oxygen-containing organic anions. Part 3. Electron spin density on alkali-metal cations chelated by radical anions as a function of interionic distance

Abstract

E.s.r. spectra of radicals derived by addition of several alkali-metals to 1,2-bispentamethylbenzoyl-, 1,2-dimesitoyl-, 1-benzoyl-2-mesitoyl-, and 1,2,4,5-tetramesitoyl-benzene were studied in nine aprotic solvents. The electron spin densities at the alkali-metal obtained from the experimental alkalimetal couplings together with previously published values (12 solvents combined with Li, Na, K, Rb, and Cs) correlate linearly with the empirical solvent parameters E_T^N(30) and DN, and with the radius of the alkali cation. This is interpreted as a consequence of the interionic distance being controlled by dipolarity and Lewis basicity of the solvent, along with the cation radius.