SYNTHESIS AND MOLECULAR-STRUCTURE OF BIS(2,6-DIMESITYLPHENYL)GALLIUM CHLORIDE, (MES(2)C(6)H(3))(2)GACL (MES=2,4,6-ME(3)C(6)H(2)) - A T-SHAPED TRICOORDINATE MOLECULE

Bis(2,6-dimesitylphenyl)gallium chloride, (Mes(2)C(6)H(3))(2)GaCl (Mes = 2,4,6-Me(3)C(6)H(2)), has been prepared by reaction of (2,6-dimesitylphenyl)lithium, Mes(2)C(6)H(3)Li, with gallium chloride in diethyl ether. The title compound crystallizes in the monoclinic space group P2(1)/n (No. 14) with unit cell parameters a = 12.256(3) Angstrom, b = 20.644(4) Angstrom c = 16.361(4) Angstrom, beta = 100.96(2)degrees, D-calcd = 1.20 g cm(-3), and V = 4064 Angstrom(3) for Z = 4. Refinement, based on 1454 observed reflections, converged at R = 0.069 and R(w) = 0.066. The Ga-Cl bond distance is 2.177(5) Angstrom, while the Ga -C bond distances are 1.956(16) Angstrom and 2.000(6) Angstrom. The steric demands associated with the two bulky 2,6-dimesitylphenyl ligands are manifested most prominently in the coordination about the gallium atom as it is sufficiently distorted from the expected trigonal planar geometry so as to approach that of the rare T-shaped configuration.