SYNTHESES, CHARACTERIZATION, CRYSTAL AND MOLECULAR-STRUCTURES, AND SOLUTION PROPERTIES OF ET2GA(C5H5) AND ETGA(C5H5)(2)

The compounds Et(2)Ga(C5H5) and EtGa(C5H5)(2) have been prepared by ligand redistribution reactions in pentane solution between appropriate quantities of GaEt(3) and Ga(C5H5)(3). Both compounds have been fully characterized by elemental analyses, X-ray structural studies, cryoscopic molecular weight studies in benzene solution, mass spectroscopic studies, H-1 NMR studies of solutions, and 1H NMR studies of melts. Both compounds exist as pure single compounds in the solid state, The compound [Et(2)Ga(C5H5)]infinity crystallizes in the centrosymmetric triclinic space group P $($) over bar$$ 1 (No. 2) with a = 7.803(2) Angstrom, b = 15.839(4) Angstrom, c = 16.318(4) Angstrom, alpha = 101.98(2)degrees, beta = 95.23(2)degrees, gamma = 102.72(2)degrees, V = 1904.5(8) Angstrom(3), and Z = 8 (monomeric units). The structure consists of polymeric chains of [Ga-C5H5]infinity, in which each gallium(III) center is linked to two ethyl ligands and is in contact with one carbon atom from each of two bridging C5H5 ligands. The other compound [EtGa(C5H5)(2)]infinity crystallizes in the noncentrosymmetric orthorhombic space group P2(1)2(1)2(1) (NO. 19) With a = 8.213(5) Angstrom, b = 9.131(4) Angstrom c = 14.277(10) Angstrom, V = 1070.7(11), and Z = 4 (monomeric units). The structure was refined to R = 7.01% for those 846 reflections above 6 sigma, This structure is also polymeric with [Ga-C5H5]infinity chains. Each gallium(III) center is also bonded to an ethyl ligand and a terminal eta(1)-C5H5 ligand. When the compounds are dissolved in benzene, toluene, cyclohexane, CHCl3, or THF, ligand redistribution reactions occur to form equilibrium mixtures of species, However, when [Et(2)Ga(C5H5)]infinity is melted, 1H NMR spectral studies suggest the existence of only Et(2)Ga(C5H5), whereas when [EtGa(C5H5)(2)]infinity is melted, a single compound does not exist and a mixture of EtGa(C5H5)(2), Et(2)Ga(C5H5), and Ga(C5H5)(3) is formed instead. Mass spectral studies of Et(2)Ga(C5H5) are consistent with the presence of Et(2)Ga(C5H5) in the gas phase, but when [Et(2)Ga(C5H5)]infinity is heated and vaporized, uncertainty regarding the identities of the species in the gas phase arises due to the occurrence of the ligand redistribution reactions in the melt.