METAL DERIVATIVES OF MOLECULAR-COMPOUNDS - IX - BIS(1,2-DIMETHOXYETHANE-O,O')LITHIUM PHOSPHANIDE, ARSANIDE, AND CHLORIDE - 3 NEW REPRESENTATIVES OF THE BIS(1,2-DIMETHOXYETHANE-O,O')LITHIUM BROMIDE TYPE

Experiments to obtain thermally unstable lithium silylphosphanide at - 60 degrees C from a 1,2-dimethoxyethane solution resulted in the isola tion of its dismutation product bis(1,2-dimethoxyethane-O,O')lithium p hosphanide (1). The homologous arsanide 2 precipitated after a frozen solution of arsane in the same solvent had been treated with lithium n -butanide at -78 degrees C. Unexpectedly, too, the analogous chloride 3 and bromide 4 were formed in reactions of 1-chloro2,2-bis(trimethyls ilyl)-1 lambda(3)-phosphaethene with (1,2-dimethoxyethane-O,O')lithium bis(trimethylsilyl)stibanide and of lithium 1,2,3,4,5-pentaphenyl-2,3 -dihydro-1 lambda(3)-phosphol-3-ide with omega-bromostyrene, respectiv ely. The monomeric complexes 1 {-100+/-3 degrees C; a = 1391.1(4); b = 809.8(2); c = 1249.1(3) pm; beta = 102.84(2)degrees}, 2 {-100+/-3 deg rees C; a = 1398.3(4); b = 819.8(3); c = 1258.5(4) pm; beta = 103.35(2 )degrees} and 3 {-100+/-3 degrees C; a = 1308.4(2); b = 788.2(1); c = 1195.6(1) pm; beta = 95.35(1)degrees} crystallize in the monoclinic sp ace group C2/c with four solvated ion pairs in the unit cell; they are isotypic with bis(1,2-dimethoxyethane-O,O')lithium bromide (4) {-73+/ -2 degrees C; a = 1319.0(2); b = 794.1(1); c = 1214.3(2) pm; beta = 96 .22(1)degrees}, already studied by Rogers et al. [13] at room temperat ure. The neutral complexes show a trigonal bipyramidal configuration o f symmetry C-2, pnicogenanide or halide anions occupying equatorial si tes {Li-P 260.4(4); Li-As 269.8(6); Li-Cl 238.6(7); Li-Br 256.3(10) pm } and the chelate ligands spanning equatorial and axial positions (Li- O-eq 205.4(4) to 207.4(4); Li-O-ax 208.9(3) to 215.5(2) pm}. The coord ination within the (dme)(2)Li fragment, the Li-X distances (X = P, As, Cl, Br), the structure of the chelate rings, and the packing of the n eutral complexes are discussed in detail.