Gallium Chloride Research Articles

Atomic and molecular spectra of vapors evolved in a graphite furnace. Part 5: gallium, indium and thallium nitrates and chlorides

The vaporization behavior and vapor spectra of Ga, In and Tl nitrates and chlorides in the tube furnace was investigated using an UV spectrometer with CCD detector. Fifty spectra in the wavelength range of 200–475 nm were collected in each experiment during the vaporization step, with temperature increase from 473 to 2673 K. The vaporization patterns were compared for the pyrocoated, non-pyrocoated graphite tubes, and Ta-lined tubes. Nitrate and chloride aqueous solutions and chloride slurries in chloroform were used to distinguish the impact of hydrolysis on the vaporization behavior of these chlorides. The spectra of oxygen and chlorine containing molecules, presumably of suboxides, chlorides and dichlorides were identified upon variation of the experimental conditions. The release of suboxide vapors due to the reduction of oxides by carbon was promoted after the decomposition of nitrates. The presence of other elements on the vaporization surface, or the isolation of the sample from the graphite surface by Ta-lining, impeded the vapor release and reduced the intensity of molecular bands. Adsorption of chlorine onto graphite caused a decrease of chloride and dichloride bands. The suboxide bands were observed in the spectra of Ga and In chlorides introduced in the tube as aqueous solutions, due to partial hydrolysis.

Synthesis and molecular structure of tris(pentamethylphenyl)gallium

Tris(pentamethylphenyl)gallium, (Me 5C 6) 3Ga, was prepared by reaction of pentamethylphenylmagnesium bromide with gallium(III) chloride in diethyl ether. The title compound, characterized by 1H and 13C NMR, elemental analyses, and single crystal X-ray diffraction, crystallizes in the P 1 ̄ (No. 2) space group with a=9.003(9) Å, b=10.713(1) Å, c=16.066(2) Å, α=107.63 (3)°, β=97.63 (3)°, γ=90.08(3)°, for Z=2. Refinement converged at R 1=0.050, wR 2=0.11. The pentamethylphenyl ligands are configured about the gallium center in a propeller fashion at angles of 67.3°, 62.3°, and 60.9°.

Reactions of Electrophiles with the Phosphaalkene Mes*PCH2: Mechanistic Studies of a Catalytic Intramolecular C−H Bond Activation Reaction

A catalytic intramolecular C−H bond activation is reported for the reaction of the phosphaalkene Mes*PCH2 (Mes* = 2,4,6-tri-tert-butylphenyl) with aluminum(III) chloride (0.05, 0.10, and 0.15 equiv). Studies of analogous reactions with gallium(III) chloride and triflic acid facilitated the identification of intermediates, thus providing insight into the reaction mechanism, which involves a phosphenium ion as a fleeting intermediate.

SiC bond cleavage in the reaction of gallium chloride with lithium bis(trimethylsilyl)amide and thermolysis of base adducts of dichloro(trimethylsilyl)amido gallium compounds

The known cyclic dimer, (Me 3SiNSiMe 2) 2 ( 1), was isolated in the reaction of GaCl 3 with one equivalent of Li[N(SiMe 3) 2] at room temperature as the result of cleavage of a SiC bond from the N(SiMe 3) 2 anion. Although the gallium product was not isolated from the GaCl 3 reaction, pyrolysis of the new base-stabilized dichloro(silyl)amido gallium compounds, Cl 2Ga[N(SiMe 3) 2](quin) ( 2) (quin=quinuclidine), Cl 2Ga[N(SiMe 3) 2](NMe 3) ( 3), Cl 2Ga[N(SiMe 3)( t Bu)](quin) ( 4) and Cl 2Ga[N(SiMe 3)(2,6- i PrC 6H 3)](quin) ( 5), afforded MeGaCl 2(quin) and MeGaCl 2(NMe 3) in 27–61% yields confirming a methyl migration from Si to Ga. The SiC bond cleavage and methyl migration were proposed to occur through transition states containing a GaNSiM e ring. No unusual Ga⋯C interaction was found in the solid-state structure of 2 that was monomeric with the gallium atom adopting a distorted tetrahedral geometry. Improved structural data for 1 are also reported.

A highly stereoselective, novel coupling reaction between alkynes and aldehydes

In the presence of indium triflate or gallium chloride, a novel coupling between internal alkynes and aldehydes occurred to give unsaturated ketones and [4+1] annulation products.

Lateral epitaxial overgrowth of GaN using diethyl gallium chloride in metal organic vapor phase epitaxy

Diethyl gallium chloride (DEGaCl) was studied as an alternative gallium source for the lateral epitaxial overgrowth (LEO) of GaN by metal organic vapor phase epitaxy. The decomposition of DEGaCl to GaCl produces growth conditions similar to those found in the hydride vapor phase epitaxy technique near the growth front producing increased lateral growth rates. Controlled vertical and sloped facets were produced through the choice of the reactor operating conditions. X-ray diffraction was used to determine the LEO tilting angles that were found to decrease with decreasing lateral-to-vertical growth rate ratio. LEO GaN using DEGaCl source has shown a smaller kink density along the growing facets under the conditions required for rapid and smooth coalescence. The increased lateral growth rates and smoother sidewall facets within DEGaCl based growth were attributed to the ‘nearer-to-equilibrium’ conditions at the growth front that can result from the presence of HCl-related etching reactions.

Synthesis and Characterization of a Trigallacycle

The reaction of equimolar quantities of 1,8-bis(trimethylstannyl)naphthalene (1) and GaCl3 in toluene at −25 °C yields the known stannagallacycle bis(μ-1,8-naphthalenediyl)(μ-chloride)methyltin(IV)chlorogallium(III) (2) and a new product which has been identified as the cyclic adduct formed between two molecules of bis(μ-1,8-naphthalenediyl)bis(gallium(III)chloride) and two molecules of trimethyltin chloride (3). Interestingly, when carried out at 25 °C and in the presence of water, this reaction leads to the formation of an additional product (4) that is a 12-membered macrocycle containing three gallium atoms linked by 1,8-naphthalenediyl ligands and arranged about a central oxygen atom. The charge balance of 4 is achieved by the presence of a chloride atom that occupies a bridging position between two of the gallium centers. Compounds 3 and 4 have been characterized by NMR, elemental analysis, and single-crystal X-ray analysis. In the crystal, 4 exists as a dimer wherein the monomers are bridged via a G...

Arene-mercury complexes stabilized aluminum and gallium chloride: synthesis and structural characterization.

Reaction of HgCl(2) with 2 equiv of MCl(3) in an aromatic solvent yields Hg(arene)(2)(MCl(4))(2) where, arene = C(6)H(5)Me, M = Al (1), Ga (2); arene = C(6)H(5)Et, M = Al (3) and Ga (4); o-C(6)H(4)Me(2), M = Al (5), Ga (6); C(6)H(3)-1,2,3-Me(3), M = Al (7) and Ga (8). The solid-state structures of compounds 1-5 and 7 have been determined by X-ray crystallography. In the solid state, compounds 1-4 and 7 exist as neutral complexes in which two arenes are bound to the mercury, and the MCl(3) groups are bound through bridging chlorides to the mercury; compound 5 exists as a cation-anion pair [Hg(o-C(6)H(4)Me(2))(2)(AlCl(4))][AlCl(4)]. However, in solution compounds 1-8 all exist as neutral complexes. The structures of Hg(arene)(2)(AlCl(4))(2) and [Hg(arene)(2)(AlCl(4))](+) have been determined by DFT calculations [B3LYP level] to facilitate the assignment of the (13)C CPMAS NMR spectra and are in good agreement with the X-ray diffraction structures of compounds 1 and 5. Reaction of HgCl(2) with MCl(3) in benzene, m-xylene, and p-xylene results in the formation of liquid clathrates whose spectroscopic characterization is consistent with ionic structures, [Hg(arene)(2)(MCl(4))][MCl(4)]. The calculated energy difference between Hg(C(6)H(5)Me)(2)(AlCl(4))(2) and [Hg(C(6)H(5)Me)(2)(AlCl(4))][AlCl(4)] is discussed with respect to the structure of compound 5 in the solid state versus solution state and the proposed speciation in the liquid clathrates.

Solvothermal Azide Decomposition Route to GaN Nanoparticles, Nanorods, and Faceted Crystallites

We report a straightforward, nonaqueous, solvothermal method for the production of nanoscale gallium nitride structures. Nanoparticles with spherical and rodlike morphologies are produced via in situ gallium azide precursor synthesis and decomposition in superheated toluene or THF. The solution reaction between gallium chloride and sodium azide produces an insoluble azide precursor that solvothermally decomposes to GaN at temperatures below 260 °C. The resulting products are poorly crystalline but thermally stable and crystallize to hexagonal GaN upon annealing at 750 °C. Product morphologies include nanoparticles (ca. 50 nm) and nanorods (ca. 300 nm lengths). Upon annealing, the nanoparticles coalesce into larger organized crystalline structures with hexagonal facets.

Kinetics of LPCVD of gallium nitride and oxynitride films based on pyrolysis of a gallium chloride complex with ammonia GaCl3NH3

The results of an experimental study on the kinetics of the LPCVD of gallium nitride and oxynitride films based on pyrolysis of a gallium chloride complex with ammonia, GaCl 3 NH 3 , are presented. The conclusions are made taking into account the results of UV spectroscopy of the reacting gas phase.

Dynamical behaviors of GaCl on the GaAs(001) 4×6 surface by pulsed molecular beam scattering

We studied dynamical behaviors of gallium chloride (GaCl) on a GaAs(001) 4×6 surface using pulsed molecular beam scattering. The angular distribution of reflected GaCl consists of two parts; inelastic direct scattering contribution and thermal desorption of trapped molecules on the GaAs(001) 4×6 surface. We divided the time of flight spectra of thermally desorbed GaCl into two components with activation energies of 22.0 and 10.5 kcal/mol corresponding to GaCl trapping wells. These wells were associated with two comparatively large domains on the GaAs(001) 4×6 surface. The relatively large activation energy is responsible for the strong dipole-electrostatic interaction between GaCl, which has a large dipole moment, and the ionic GaAs crystal.

Preparation and Structure of Cyclic Gallium(III) and Gallium(II) 2-Amino-ethyl-amides

Abstract The reaction of N,N′-di(tbutyl)-ethane- 1,2-diamine with NaH followed by anhydrous GaCl3 (molar ratios 1:2 :1) gives mainly an insoluble bis(diamido)gallium chloride together with a low yield (28%) of a soluble monocyclic dichlorogallium-[2-(tbutylamino)-ethyl-(tbutyl)amide], Cl2Ga(tBuNH-CH2CH2-NtBu) 1, the structure of which has been determined. Metallation of the same diamine with tbutyl-lithium and GaCl3 (1:2:1) gave small quantities of the corresponding dinuclear, bicyclic gallium(II) compound 2, [(tBuNH-CH2CH2-NtBu)GaCl]2 with a Ga-Ga single bond connecting the two units, as again shown by a single crystal X-ray diffraction analysis.

Solvent Effect on the Partial Molar Volume and the Enthalpy of Solution of Gallium Chloride

Partial molar volumes and heats of solution were determined for gallium chloride in benzene, toluene, o-xylene, mesitylene, 1,2-dichloroethane, ethyl acetate, acetonitrile, and 1,4-dioxane. A proportionality in changes in these characteristics is observed for weak π,ν-type complexes in alkylbenzene medium. The partial molar volumes of strong n,ν-type complexes approach a limiting value.

Low-Temperature Solvothermal Route to GaN Nanoparticles

ABSTRACTWe report a straightforward, non-aqueous solvothermal method for the production of nanoscale gallium nitride structures. Nanoparticles with spherical and rod-like morphologies are produced via in situ gallium azide precursor synthesis and decomposition in superheated toluene or THF. The solution reaction between gallium chloride and sodium azide produces an insoluble azide precursor that is then solvothermally decomposed to GaN at temperatures below 260 °C. The resulting products are poorly crystalline but thermally stable and crystallize to hexagonal GaN upon annealing at 750 °C. Product morphologies include spherical particles (ca. 50 nm) and nanorods. Upon annealing, the nanoparticles coalesce into larger organized crystalline structures with hexagonal facets.

In further pursuit of the carbene analogy: preparation and crystal structure of (N,N,N ′,N ′-tetramethylethylenediamine)potassium [cis-ethene-1,2-di(tert-butylamido)]gallate(I)

Reduction of cis-ethene-1,2-di(tert-butylamido)gallium(III) chloride with metallic potassium in the presence of N,N,N′,N′-tetramethylethylenediamine gives the title compound which has a novel dimeric structure with the potassium cations η5-coordinated to the pseudo-carbene ring system of one monomer and η1-bonded to the gallium atom of the other.

Highly active, reusable and moisture insensitive catalyst obtained from basic Ga-Mg-hydrotalcite anionic clay for Friedel-Crafts type benzylation and acylation reactions

Liquid phase benzylation (by benzyl chloride) and acylation (by benzoyl chloride) of benzene and toluene over a Ga–Mg hydrotalcite (which is a basic anionic clay) with or without HCl gas pretreatment and also over the hydrotalcite used earlier in the toluene benzylation (at 110 °C) have been investigated. The fresh, used and HCl-gas-pretreated hydrotalcite catalysts were characterized for their surface area, basicity, crystalline structure and phases and also for their surface composition. The fresh hydrotalcite showed no catalytic activity for both the benzylation and benzoylation reactions for a long period. However, after a long induction period (2.7 h), the catalyst showed a very high activity in the toluene benzylation (at 110 °C). Whereas, the catalyst after its use in the toluene benzylation or after its HCl gas pretreatment showed very high activity for both the reactions with a much shorter induction period. The hydrotalcite-derived catalyst consists essentially highly dispersed gallium and magnesium chlorides on MgO. The presence of moisture in the reaction mixture has beneficial effects on the acylation reactions over the used catalyst.

First syntheses and X-ray structures of a meso-alkyl-substituted corrole and its Ga(III) complex

The solvent-free condensation of heptafluorobutanal and pyrrole leads to the corresponding meso-alkyl-substituted corrole, which was metallated by gallium chloride to provide the first first-row non-transition-metal corrole. Both the ligand and the complex were characterized by X-ray crystallography.

Formation Mechanism of the Ga13 Keggin Ion: A Combined EXAFS and NMR Study

The base hydrolysis of gallium chloride and gallium nitrate was followed by combining 71Ga NMR and Ga K-edge X-ray absorption spectroscopy measurements. Using such an approach, it can be shown unambiguously that the solution contains various trimeric and tetrameric species in the early hydrolytic stages before the formation of the Ga13 polycation. This Keggin-type structure would then form by condensation of trimers and tetramers in disagreement with all of the previously published models that assume the existence of a monomer either tetrahedral or octahedral. In view of the parallel behavior of aluminum and gallium, this work can certainly be used to reach a better understanding of the hydrolytic chemistry of aluminum. This is of prime importance regarding the crucial role of this metal in natural systems and its widespread use as a coagulant in water treatment operations.

Gallium nitride growth using diethyl gallium chloride as an alternative gallium source

Diethyl gallium chloride (DEGaCl) was employed as an alternative gallium precursor in the epitaxial growth of GaN for producing a hydride vapor-phase epitaxy (HVPE)-like growth chemistry in a metal-organic vapor-phase epitaxy (MOVPE) system. The standard ‘two-step’ GaN growth process was carried out using this Cl-containing precursor and compared to the conventional growth using trimethyl gallium (TMGa) source under identical reactor conditions. The growth rate during DEGaCl-based growth decreases with increasing temperature, indicating that the growth front may be close to local thermodynamic equilibrium. A direct comparison of materials properties associated with these precursors in various structural combinations of buffer and high-temperature GaN epilayers was performed. Improved material properties and a significant difference in the surface morphology were observed in the case of DEGaCl-based high-temperature growth, as determined by X-ray diffraction, capacitance–voltage, atomic force microscopy and photoluminescence measurements. We attributed the improved growth behavior to the ‘nearer-to-equilibrium’ growth front that could result from the presence of HCl-related etching reactions.

Monochlorogallane: physical properties and structure of the gaseous molecule H2Ga(mu-Cl)2GaH2 as determined by vibrational, electron diffraction, and ab initio studies.

Monochlorogallane, synthesized by the metathesis of gallium(III) chloride with an excess of trimethylsilane at ca. 250 K, has been characterized by chemical analysis, by its IR, Raman, and 1H NMR spectra, and by the products of its reaction with trimethylamine. The vibrational spectra of the vapor species isolated in solid Ar, N2, or CH4 matrixes at ca. 12 K imply the presence of only one species, viz. the dimer with an equilibrium structure conforming to D2h symmetry. The structure of this molecule has been determined by gas-phase electron diffraction (GED) measurements augmented by the results of ab initio molecular orbital calculations. An equilibrium structure with D2h symmetry has been assumed in the analysis of the electron diffraction pattern. However, as the molecule has a very low frequency Ga(mu-Cl)2Ga ring-puckering mode, a dynamic model was used to describe it with the aid of a set of pseudoconformers spaced at even intervals (deltadelta = 5 degrees, deltamax, = 20 delta) around the ring-puckering angle delta and Boltzmann-weighted according to a quartic potential V(delta) = V4delta4 + V2delta2. The differences in bond distances and angles between the different pseudoconformers were constrained to the values derived from the ab initio calculations employing second-order Moller-Plesset (MP2) methods (with all the electrons included in the correlation calculations) and a 6-311G(d) basis set. The results for the weighted average of the principal distances (ralpha) and angles (<alpha) (with estimated 1sigma uncertainties) from the combined GED/ab initio study are r(Ga-Cl) 2.350(2) A, r(Ga-H) 1.523(20) A, <Cl-Ga-Cl 89.7(5)degrees, <H-Ga-H 135.1 degrees, V4 3.0 x 10(-6) kcal mol(-1) deg(-4), and V2 6.0 x 10(-4) kcal mol(-1) deg(-2).