INTERACTIONS IN CRYSTALS .63. CRYSTALLIZA TION AND STRUCTURE DETERMINATION OF 1,2-DIMESITOYLBENZENE AND OF BIS(HYDROGEN-1,2-DIMESITOYLBENZENE)-DISODIUM BIS(ETHYLENDIAMINE)

Chelate complexes of 1,2-dimesitoylbenzene radical anion with alkali m etal cations exhibit in aprotic solution extremely large ESR/ENDOR met al coupling constants. For rationalization, structures of both the neu tral molecule (H3C)(3)H2C6-CO-C6H4-CO-C6H2(CH3)(3), in which the two c arbonyl groups are twisted out of the benzene ring plane by dihedral a ngles of +/-<(37)over bar>degrees, and a sodium contact ion quadruple have been determined. One of the dimers [dimesitoylbenzeneH(-) (Na+H2N H2C-CH2NH2)](2), although generated by Na metal mirror reduction of 1, 2-dimesitoylbenzene in aprotic DME solution with added ethylendiamine for better electron transfer, surprisingly contains two 245 pm short ( \) hydrogen bridges O-- ...(H)O and in addition two solvation bridges O-- ... NaO+(H2NH2C-CH2NH2)... O-. Results of MNDO calculations based on the experimental coordinates support;he proposed concept.