2,2'-BIPYRIDINE COMPLEXES OF THE LITHIUM CHALCOGENOLATES LI(EPH) AND LI(NC(5)H(4)E-2) (E=S OR SE)

2,2'-Bipyridine (bipy) forms stable crystalline co-ordination complexes with lithium benzeneselenolate and lithium pyridine-2-selenolate. The compounds are insoluble in aromatic hydrocarbons, slightly soluble in pyridine, and extremely soluble in tetrahydrofuran, from which they can be crystallized in ca. 70% yield. Both complexes have been characterized by elemental analysis, NMR, IR, and single-crystal X-ray diffraction. Compound [{Li(bipy)(SePh)}2] 1 [space group P2(1)/m, a = 9.493(4), b = 16.866(5), c = 10.112(9), beta = 114.53(6)-degrees and Z = 4] is a dimer containing two lithium ions bridged by a pair of symmetric benzeneselenolate ligands, with bidentate bipy ligands bound to each lithium ion. In compound [{Li(bipy)(NC5H4Se-2)}2] 2 [space group P2(1)/n, a = 10.361(5), b = 13.521(4), c = 11.062(5) angstrom, beta = 117.21(4)-degrees and Z = 4] each lithium ion is bound to a bidentate bipy ligand, one bridging selenium atom, and the nitrogen atom from the second bridging pyridine-2-selenolate ligand, thus forming an eight-membered Li-Se-C-N-Li-Se-C-N ring. The analogous lithium thiolates have also been prepared in 70% yield; they are not isostructural with the selenolates.