1,4-DILITHIO-1,2,3,4-TETRAPHENYL-BUTADIENE - CRYSTAL-STRUCTURE OF THE1,2-DIMETHOXYETHANE ADDUCT

The crystal structure of Li2C4Ph4 . 2DME (1, DME = 1,2-dimethoxyethane ) is reported. In the solid state it is monomeric owing to the chelati ng properties of the bidentate donor solvent. The butadiene backbone e xhibits cis-geometry with two essentially localized C-C double bonds, separated by a C-C single bond. The lithium ions coordinate on opposit e sides of the C4-backbone. They show short contacts to the terminal C -atoms of the butadiene moiety and significantly longer ones to the ce ntral C-atoms. No interactions between the Li+ ions and the phenyl rin gs were observed. Crystal data (Mo-Kalpha radiation) at -120-degrees-C for 1 . 0.5C5H12: a = 1036.5(4) pm, b = 1084.0(5) pm, c = 1709(1) pm, alpha = 105.11(4)-degrees, beta = 103.25(4)-degrees, gamma = 97.51(4) -degrees, triclinic, space group P1BAR, R = 0.083 for 3727 (F > 6sigma (F)) data.