SYNTHESIS AND STRUCTURE OF THE NEUTRAL 3-COORDINATE GALLIUM SELENOLATE GA[SE(2,4,6-TERT-BU3C6H2)]3 AND THE MONOMERIC LITHIUM SELENOLATE LI(THF)3SE(2,4,6-TERT-BU3C6H2)

The homoleptic gallium selenolate Ga[Se(2,4,6-t-Bu3C6H2)3 has been synthesized by the reaction of GaCl3 with 3 equiv of LiSeMes* (Mes* = 2,4,6-t-Bu3C6H2) in toluene. It was characterized by H-1 NMR and infrared spectroscopy and by X-ray crystallography. The gallium center has a three-coordinate, almost planar, coordination with Ga-Se bond lengths of nearly 2.324 angstrom. The precursor lithium selenolate species Li(THF)3SeMes* was also crystallized and structurally characterized. Like its sulfur analogue, it possesses a monomeric structure with the Li center bound to three THF molecules and a selenium in a pseudotetrahedral manner. The Li-Se distance is near 2.57 angstrom and the LiSeC angle is about 101.9-degrees. Crystal data with Mo K-alpha (lambda = 0.710 69 angstrom) radiation at 130 K: 1, Ga[Se(2,4,6-t-Bu3C6H2)]3.2PhMe, a = 14.523 (3) angstrom, b = 14.925 (6) angstrom, c = 16.651 (3) angstrom, alpha = 85.92 (3)-degrees, beta = 83.50 (2)-degrees, gamma = 61.39 (2)-degrees, Z = 2, triclinic, space group P1BAR, R = 0.065; 2 Li(THF)3Se(2,4,6-t-Bu3C6H2), a = 10.758 (5) angstrom, b = 18.003 (6) angstrom, c = 17.954 (5) angstrom, alpha = 62.50 (2)-degrees, beta = 89.61 (3)-degrees, gamma = 87.91 (3)-degrees, Z = 4 (two independent molecules), triclinic, space group P1BAR, R = 0.054.