Synthesis and characterization of mesitylgallium chloride compounds including the crystal and molecular structure of dichloromesitylgallium(III), an inorganic polymer

Article abstract of DOI:10.1021/om00153a010

The mesitylgallium chloride compounds GaMes₂Cl and GaMesCl₂ have been prepared and fully characterized by melting point data, elemental analyses, solubility properties, IR and ¹H and ¹³C NMR spectroscopic data, and Lewis acidity studies. Cryoscopic molecular weight studies of GaMes₂Cl in benzene solution are consistent with the presence of dimeric molecules. Lewis bases such as Et₂O and THF react with (GaMes₂Cl)₂ in benzene to establish two equilibria which are consistent with the presence of the dimer, a monochloride bridged 2:1 adduct [(GaMes₂Cl)₂·base], and the 1:1 adduct. The dichloro derivative GaMesCl₂ is an unusually high melting solid which is insoluble in hydrocarbon solvents and crystallizes in the centrosymmetric monoclinic space group P2₁/m (C_2h²; No. 11) with a = 8.3989 (21) A?, b = 6.9976 (19) A?, c = 18.0347 (57) A?, β = 100.159 (23)°, V = 1043.3 (5) A?³, and Z = 4 (formula units). Diffraction data (Mo Kα, 2θ = 5.0-45.0°) were collected with a Syntex P2₁ diffractometer, and the structure was refined to R_F = 6.2% for all 1502 independent reflections. Dichloromesitylgallium(III) is a one-dimensional polymer in which planar GaMesCl (Mes = mesityl) units are linked by bridging chloride ligands. The correct formulation is [Ga(C₆H₂Me₃)Cl(μ-Cl)]_∞. Distances of interest include Ga?Ga = 3.781 (1) A?, Ga-Cl(terminal) = 2.150 (4)-2.164 (4) A?, Ga-Cl(bridging) = 2.363 (3)-2.369 (3) A?, and Ga-C(mesityl) = 1.943 (12)-1.970 (14) A?.