Crystallization and Structure Determination of 1 , 2-Dimesitoylbenzene and of Bis ( hydrogen-l , 2-dimesitoylbenzene )-disodium-bis ( ethylendiamine )

Chelate complexes of 1,2-dimesitoylbenzene radical anion with alkali metal cations exhibit in aprotic solution extremely iarge ESR/ENDOR metal coupling constants. For rationaliza­ tion, structures of both the neutral molecule (H 3C)3H2C6C O C 6H4 C O C 6H2(CH3)3, in which the two carbonyl groups are twisted out of the benzene ring plane by dihedral angles of ± 37°, and a sodium contact ion quadruple have been determined. One of the dimers [dimesitoylbenzeneH® (Na®H2N H 2C -C H 2N H 2)]2, although generated by Na metal mirror reduction of 1,2-dimesitoylbenzene in aprotic DM E solution with added ethylendiamine for better electron transfer, surprisingly contains two 245 pm short (!) hydrogen bridges e O — (H)O and in addition two solvation bridges e O —Na®(H2N H 2C -C H 2NH2) —O 0 . Results of MNDO calculations based on the experimental coordinates support the proposed concept.