GaCl3 Research Articles

ChemInform Abstract: Gallium Trichloride Promoted Ethynylation Reaction of 1,4‐Dienes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Gallium Trichloride‐Promoted Ethynylation Reaction of 1,4‐Dienes

AbstractCyclopentadienes and silylated 1,4‐dienes were deprotonated with gallium trichloride (GaCl3), and the resultant pentadienylgalliums underwent an ethynylation reaction with chlorosilylethyne. The silyl substituent on the olefin had an effect to increase the acidity of the allylic protons.

Gallium Trichloride–Promoted Highly Regioselective Ring Opening of Epoxides with NH4SCN and NaN3 in Water

β‐Hydroxy thiocyanates and β‐azidoalchols were obtained in excellent yields via GaCl3‐promoted highly regioselective ring opening of epoxides with ammonium thiocyanate or sodium azide in water. The present method is very rapid and equally compatible for both ammonium thiocyanate and sodium azide.

Increasing the Lability of Polarised Phosphorus–Phosphorus Bonds

AbstractDiphosphanes with polarised P–P bonds react readily with Lewis acids like borane, gallium trichloride, or with elemental selenium, to give products arising from electrophilic attack at the more basic phosphorus atom and consecutive bond cleavage. Spectroscopic studies proved that the initial reaction with borane proceeds under preservation of the P–P bond to give a transient phosphane–borane which rearranged below ambient temperature. The results suggest that Lewis acid coordination decisively enhances the weakening of the polarised P–P bond. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Formation and Characterization of the Cationic Gallane Derivatives [(RH2N)2GaH2]Cl (R = Me or iPr) and [{(iPrH2N)GaH2NHiPr}2GaH2]Cl

AbstractThe reaction of LiGaH4 with an excess of the hydrochloride of a primary amine RNH2 in ether solution yields in [(RH2N)2GaH2]Cl (R = Me, 1, or iPr, 2) additional examples of cationic gallane derivatives. The cation [(iPrH2N)2GaH2]+ reacts further with LiGaH4, also in ether solution, with H2 elimination and formation of the trigallium cationic derivative [{(iPrH2N)GaH2NHiPr}2GaH2]Cl, 3. Prolonged standing of [(iPrH2N)2GaH2]Cl in the presence of LiCl results in partial exchange of Ga–H by Ga–Cl bonds, with the isolation in low yield of crystals, 4, of [(iPrH2N)2GaH2]Cl in which about 7 % of the H atoms attached to Ga were replaced by Cl. All of the compounds 1–4 having been characterized crystallographically, the results are discussed in relation to the different reaction pathways open to [RNH3]Cl and LiMH4 (M = Al or Ga). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Twofold Hydrogallation of C⋮C Triple Bonds by H−GaCl2Synthesis of Chelating Lewis Acids and Their Application in Adduct Formation

The twofold addition of Ga-H to Ctriple bonds C triple bonds (hydrogallation) did not succeed by treatment of alkynes with an excess of dialkylgallium hydrides. In contrast, double hydrogallation was easily achieved by the reactions of H-GaCl(2) with trimethylsilyl-substituted alkynes [trimethylsilylphenylethyne and 1,4-bis(trimethylsilylethynyl)benzene] in appropriate stoichiometric ratios. The monoalkyne yielded the compound [H(5)C(6)-CH(2)-C(SiMe(3))(GaCl(2))(2)](2), 1, which was only sparingly soluble in n-hexane. Crystal structure determination revealed a dimeric formula unit possessing two parallel Ga(2)Cl(2) heterocycles in the solid state. Treatment of the dialkyne with four equivalents of the hydride gave a colorless precipitate, which was completely insoluble in hydrocarbons. Addition of diethyl ether to both products afforded soluble and monomeric etherates 1(OEt(2))(2) and 2 in which the two or four gallium atoms, respectively, were coordinated by ether molecules. Preliminary experiments with simple Lewis bases showed the principle capability of 1 to act as an effective chelating Lewis acid. Adducts of the type [H(5)C(6)-CH(2)-C(SiMe(3))(GaCl(2))(GaClX)(micro-Cl)]- (4-6) resulted upon treatment with halide ions (X = Cl, Br, I).

Role of chlorine in the dynamics of GaN(0001) surface during HVPE GaN growth—Ab initio study

Abstract Atomistic processes, involving chlorine, occurring at GaN(0 0 0 1) surface during hydride vapor-phase epitaxy (HVPE) growth, were modeled, using ab-initio quantum mechanical density functional theory (QM DFT) SIESTA code. The process of adsorption of hydrogen chloride (HCl) at the surface was simulated. Both Ga-rich and N-rich surface conditions were considered. For both cases it was assumed that hydrogen is abundant, which leads to H and NH 2 coverage for Ga-rich and N-rich state of the surface, respectively. By modeling a HCl molecule, approaching the surface, it was shown that two states exist: physisorbed at far distance, and chemisorbed at closer location. For both the cases, i.e. N-rich and Ga-rich, the physical adsorption is barrierless. The transition to chemically adsorbed state encounters an energy barrier that severely depends on the state of the GaN(0 0 0 1) surface. In the case of the Ga-rich surface, the barrier is relatively small, of the order of 0.2 eV. In the case of the N-rich surface, a high-energy barrier exists, close to 2 eV. At the final i.e. chemisorbed state, the molecule disintegrates, leaving chlorine atom strongly attached to the topmost Ga atoms; the hydrogen atom is detached and paired with the other hydrogen atom. The adsorption of HCl molecule approaching Ga–H radical, located on top of NH 2 coverage, occurs via physic to chemi-sorbed state. The transition to chemically adsorbed state requires surmounting the energy barrier of about 0.6 eV: free H 2 molecule is left and the Ga–Cl admolecule remains at the surface. As before, H coverage is ineffective in protection of gallium against HCl attack. The desorption of chlorine atom from the GaCl admolecule, attached at the GaN(0 0 0 1) surface, was also analyzed. Single Cl atom desorption encounters a high-energy barrier, of the order of 4.5 eV. The desorption of HCl, involving the additional H atom, needs to overcome a significantly lower-energy barrier, of the order of 0.6 eV, creating a possible path of chlorine removal from the surface.

GaAlCl -grafted Mont.K-10 clay: Highly active and stable solid catalyst for the Friedel-Crafts type benzylation and acylation reactions

A liquid phase reaction of anhydrous GaCl 3 and AlCl 3 with the surface hydroxyl groups (with HCl evolution) of Mont.K-10 clay in dry CCL 4 under reflux resulted in a novel GaAlCl x -grafted Mont.K-10 catalyst [with Cl/(Ga + Al) = 1]. The catalyst showed high activity and stability in the Freidel-Crafts type benzylation and benzoylation (by benzyl chloride and benzoyl chloride, respectively) of benzene, naphthalene and substituted benzenes, even in the presence of moisture. It also showed good activity for the benzoylation of nitrobenzene (i.e. even in the presence of strong electron withdrawing group, like nitro group, attached to the benzene ring). The catalytically active surface species in the catalyst are –(O) 2 –Ga(or Al)Cl.

Heterozyklische Verbindungen mit fünfgliedrigen ESi4‐Ringen (E = Ga, In)

AbstractHeterocyclic Compounds Containing Five‐membered ESi4 Rings (E = Ga, In)Treatment of the dimeric indium(II) subhalide (In2R2Cl2)2 [R = C(SiMe3)3] possessing In‐In single bonds with the dipotassium tetrasilane dianion [K(18‐crown‐6)+]2[Si(SiMe3)2‐SiMe2‐SiMe2‐Si(SiMe3)2] (1) did not yield the corresponding six‐membered In2Si4 heterocycle by salt elimination. Instead cleavage of the In‐In bond occurred, and a compound containing a five‐membered InSi4 heterocycle (2) was isolated in a low yield. An ionic compound was formed with the indium atoms of the anions coordinated by two silicon and two chlorine atoms. The counterion [K2(18‐crown‐6)3]2+ contained two potassium atoms bridged by a crown ether molecule. Compound 2 and the corresponding gallium derivative 3 were obtained on a specific route by the reaction of the tetrasilane dianion with indium or gallium trichloride.

Adducts of Gallium Trichloride and Bis(trimethylsilyl)sulfur Diimide

AbstractThe monoadduct of GaCl3 with bis(trimethylsilyl)sulfur diimide (1) was synthesized and fully characterized. In the attempt to synthesize and isolate the diadduct of bis(trimethylsilyl)sulfur diimide (2), an astonishing GaCl3 diadduct of 3,3,5,5‐tetramethyl‐4,3,5,1,2,6‐oxadisilathiadiazine (3) was obtained. The formation of the six‐membered heterocycle can be explained by a methyl/chlorine exchange with GaCl3 as transfer reagent followed slow hydrolysis along with a condensation process. The structure of 1 and 3 was determined by single crystal X‐ray studies (1: monoclinic, P21/c, a = 11.187(2) Å, b = 9.338(2) Å, c = 18.117(6) Å, β = 111.80(2)° V = 1757.2(8) Å3, Z = 4; 3: monoclinic, C2/c, a = 19.950(6) Å, b = 8.722(2) Å, c = 12.078(2) Å, β = 114.60(4)°; V = 1910.8(8) Å3, Z = 4).

Gallium Trichloride‐Catalyzed Exhaustive α‐Ethynylation Reaction of 1‐Silylacetylenes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Thermodynamics of vaporization of gallium trichloride

The unsaturated and saturated pressures of gallium trichloride vapor were measured by the static method with membrane-gauge manometers in wide pressure (0.2–760 Torr) and temperature (313–1071 K) intervals. Scanning calorimetry was used to determine the thermodynamic characteristics of GaCl3 fusion. The thermodynamic characteristics were obtained for sublimation, fusion, vaporization, and association in the vapor of GaCl3 molecules. The enthalpies of formation and the absolute entropies of GaCl3 in the liquid and gaseous phases and Ga2Cl6 in the gaseous phase were calculated using literature data.

μ-1,2-Bis(diphenylphosphino)ethane-κ2P:P-bis[trichloridogallium(III)

The centrosymmetric mol­ecule of the title compound, [(GaCl3)2(C26H24P2)] or [(GaCl3)2{μ-Ph2P(CH2)2PPh2}], consists of two pseudo-tetra­hedral Ga centres coordinated by three Cl atoms [Ga—Cl = 2.1608 (8)–2.1648 (8) A] and bridged by the diphosphane ligand [Ga—P = 2.3854 (8) A].

Structural diversity in gallium(iii) complexes of the tripodal triarsine MeC(CH2AsMe2)3

The preparation and crystal structures of the first examples of gallium halide complexes with the tripodal arsine, MeC(CH(2)AsMe(2))3, reveal three distinctly different coordination modes for the ligand; the neutral [{micro(3)-MeC(CH(2)AsMe(2))3-kappaAs:kappaAs':kappaAs''}(GaI(3))3] with the triarsine coordinating to three GaI(3) units, [{Me(2)AsCH(2)C(Me)(CH(2)AsMe(2))2-kappa(2)AsAs'}GaCl(2)][GaCl(4)] involving bidentate chelation to a GaCl2+ cationic unit with the third As donor atom uncoordinated, and [{MeC(CH(2)AsMe(2))3-kappaAs:kappa(2)As'As''}(GaCl3)(GaCl2)][GaCl4] in which the triarsine forms a bidentate chelate to the GaCl2+ unit and the third As donor atom binds to a further GaCl3 unit.

Studien zur Reaktion von [Me2AlP(SiMe3)2]2 mit basenstabilisierten Organogalliumchloriden und ‐hydriden

AbstractInvestigations on the Reactivity of [Me2AlP(SiMe3)2]2 with Base‐stabilized Organogalliumhalides and ‐hydrides[Me2AlP(SiMe3)2]2 (1) reacts with dmap−Ga(Cl)Me2, dmap−Ga(Me)Cl2, dmap−GaCl3 and dmap−Ga(H)Me2 with Al‐P bond cleavage and subsequent formation of heterocyclic [Me2GaP(SiMe3)2]2 (2) as well as dmap−AlMexCl3−x (x = 3 8; 2 3; 1 4; 0 5). The reaction between equimolar amounts of dmap−Al(Me2)P(SiMe3)2 and dmap−Ga(t‐Bu2)Cl yield dmap−Ga(t‐Bu2)P(SiMe3)2 (6) and dmap−AlMe2Cl (3). 2–8 were characterized by NMR spectroscopy, 2 and 6 also by single crystal X‐ray diffraction.

Gallium-mediated allyl transfer from bulky homoallyl alcohol to aldehydes or alkynes: Control of dynamic σ-allylgalliums based on retro-allylation reaction

A new method for the preparation and control of dynamic σ-allylgalliums is disclosed. Upon treatment with a Grignard reagent and gallium trichloride, bulky homoallyl alcohols undergo gallium-mediated retro-allylation reaction to provide σ-allylgallium reagents. The σ-allylgallium reagents generated were applied to carbonyl allylation. The retro-allylation reaction generates ( Z)- and ( E)-σ-crotylgalliums stereospecifically, starting from erythro- and threo-homoallyl alcohols, respectively. The stereochemically defined crotylgallium reagents effected stereoselective allylation of aldehydes. Allylgallation reaction of alkynes with the allylgallium reagents prepared by retro-allylation is also described.

Lewis Acid Adducts of [PCl2N]3.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Axially Modified Gallium Phthalocyanines and Naphthalocyanines for Optical Limiting

AbstractFor Abstract see ChemInform Abstract in Full Text.

Lewis Acid Adducts of [PCl2N]3

Reaction of aluminum trichloride or gallium trichloride with the extremely weak base hexachlorotriphosphazene gives adducts in which the group 13 element is bound to a phosphazene nitrogen atom. In solution, the adducts exhibit fluxional behavior. The phosphazene ring of the adducts is distorted into a slight chair conformation.

Radical Allylation, Vinylation, Alkynylation, and Phenylation Reactions of α‐Halo Carbonyl Compounds with Organoboron, Organogallium, and Organoindium Reagents.

AbstractFor Abstract see ChemInform Abstract in Full Text.