13572-93-5Relevant articles and documents
Gallane: Synthesis, physical and chemical properties, and structure of the gaseous molecule Ga2H6 as determined by electron diffraction
Pulham, Colin R.,Downs, Anthony J.,Goode, Michael J.,Rankin, David W. H.,Robertson, Heather E.
, p. 5149 - 5162 (1991)
The elusive binary hydride of gallium, [GaH3]m, has at last been synthesized in rigorously conditioned all-glass apparatus by the reaction between monochlorogallane, [H2GaCl]2, and lithium tetrahydridogallate, LiGaH4, near -30 °C. The compound, which decomposes to the elements at ambient temperatures, has been characterized by chemical analysis, by its vibrational and 1H NMR spectra, and by chemical trapping with trimethylamine. The infrared spectra of the vapor species at low pressures (sampled directly at ambient temperatures or trapped in a solid inert matrix at ca. 20 K, and including the results of deuteration experiments) leave little doubt that the principal component is the diborane-like molecule H2Ga(μ-H)2GaH2. Such a conclusion is endorsed by electron-diffraction measurements, carried out on the vapor at ca. 255 K; these are consistent with an ra structure featuring the following parameters: r(Ga?Ga) 258.0 (0.2), r(Ga-Hb) 151.9 (3.5), and r(Ga-Hb) 171.0 (3.8) pm; and ∠Ga-Hb-Ga 97.9 (3.2)° (Ht = terminal H atom; Hb = bridging H atom). The molecule Ga2H2 is highly susceptible to aggregation. The vibrational spectra of the solid suggest the presence of an oligomer [GaH3]n where n > 2 and possibly equal to 4, but still retaining terminal Ga-H bonds (cf. α-AlH3). A similar species is probably a major constituent of toluene-dg solutions of the gallane; at temperatures a solution displays two distinct 1H magnetic resonances with relative intensities 2:1 attributable to Ht and Hb atoms. The reactions of gallane appear mostly to parallel those of diborane. Thus, symmetrical cleavage of the Ga(μ-H)Ga bridges occurs with NMe3 (at -95 °C) or PH3 (under matrix-isolation conditions) to give the corresponding molecular adduct LnGaH3 (L = NMe3, n = 1 or 2; L = PH3 n = 1), whereas NH3 causes unsymmetrical cleavage at -95 °C with the formation of [H2Ga(NH3)4]+GaH4 -. Quantitative metathesis with HCl brings about Ga-H/Ga-Cl exchange with the production of H2, while stepwise insertion into the Ga-H bonds is the path taken by the reaction with C2H4, affording Ga-Et derivatives.
Matrix-isolation and mass-spectrometric studies of the thermolysis of [Me2N(CH2)3]GaMe2. Characterization of the monomeric organogallanes Me2GaH, MeGaH2, and MeGa
Muller, Jens,Sternkicker, Henning,Bergmann, Ulf,Atakan, Burak
, p. 3627 - 3634 (2008/10/08)
The thermolysis of the intramolecularly coordinated gallane [Me2N(CH2)3]GaMe2 (1) under various conditions has been investigated with matrix-isolation techniques (IR spectroscopy) and with mass spectroscopy (MS). The fragmentation of compound 1 begins above 600 °C; the IR and MS data are in agreement with a proposed /J-hydrogen elimination reaction to give allyldimethylamine and dimethylgallane, Me2GaH. As deduced from the IR spectra of matrix-isolated species, the thermolysis mixtures contain the monomeric gallanes Me2GaH and MeGaH2, which have been identified with the help of ab initio and DFT calculations. The calculated frequencies [B3LYP/6-31 l+G(2d, p) and MP2(fc)/6-311+G(2d, p)] are compared with measured IR absorptions. The geometries of Me2GaH and MeGaH2 have been calculated using several methods [HF, MP2(fc), B3LYP] and basis sets [6-31G(d), 6-311G(d, p), 6-311+G(2d, p)], and the results are discussed and compared with known literature data. Aside from the monomeric hydrides, the argon matrices of the thermolyses experiments contained CH4, HCN, H2C=CH2, H2C=C=CH2, H2C=NMe, [H2CCHCH2], H2C=CHCH3, HX, and MeGa. Whereas the carbon-containing species have been identified by comparison with known literature data, methylgallium(I), well-known from mass spectroscopy, was characterized for the first time by IR spectroscopy as a matrix-isolated species. The experimental vibrational frequencies of GaMe are compared with harmonic frequencies calculated at several levels of theory.
