SYNTHESIS AND CRYSTAL-STRUCTURE OF A MIXED BIS(ARENE)GALLIUM(I) COMPLEX - DIMERIC (ETA-6-1,2,4,5-TETRAMETHYLBENZENE) (ETA-6-TOLUENE)GALLIUM(I) TETRACHLOROGALLATE(III)

The title compound (η6-1,2,4,5-tetramethylbenzene)(η6-toluene)gallium(I) tetrachlorogallate(III) (1) crystallizes from dilute solutions of equimolar quantities of gallium(I) tetrachlorogallate(III) and 1,2,4,5-tetramethylbenzene (durene) in toluene on slow cooling to 0°C. More concentrated solutions yield the 1 : 1 complex (1,2,4,5-C6H2Me4)Ga+Ga Cl4- (2). The crystals of compound 1 contain centrosymmetrical dimers, {[(η6-C6H2Me4)(η6-C6H5Me)Ga]GaCl4}2, in which each gallium(I) centre is hexahapto-bonded to one durene and one toluene molecule. The two aromatic hydrocarbons of these bent-sandwich moieties form an interplane angle of 58°. With a metal-to-ring distance of 2.642 Å, the durene ring is much closer to the Ga+ atom than the toluene ring (3.039 Å). The Ga+ atoms are bridged via two slightly distorted GaCl4- tetrahedra through contacts with three of the four chlorine atoms. The structure resembles that of the [(C6H6)2Ga]GaX4 complexes with X = Cl, Br. © 1990.