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-dimesit ylphenyl)lithium, Mes(2)C(6)H(3)Li, with gallium chloride in diethyl e ther. The title compound crystallizes in the monoclinic space group P2 (1)/n (No. 14) with unit cell parameters a = 12.256(3) Angstrom, b = 2 0.644(4) Angstrom c = 16.361(4) Angstrom, beta = 100.96(2)degrees, D-c alcd = 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 b ond 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 ato m as it is sufficiently distorted from the expected trigonal planar ge ometry so as to approach that of the rare T-shaped configuration.