Gallium Center Research Articles

Organo Group 13 metal complexes of d-block elements: VII. Stable organogalliumtetrahydroborates: Novel precursors for the deposition of gallium-containing mixed metal thin films

Novel, mixed substituted organogallium compounds of the type (R 1)(R 2) Ga[(CH 2) 3N R 2] (R 1, R 2  Cl, BH 4, alkyl, (η 5-C 5H 5)(CO) 2Fe; R  CH 3, C 2H 5) have been synthesized and fully characterized. These compounds are stabilized by intramolecular adduct formation at the gallium centre. The solid state structures of [(η 5-C 5H 5)(CO) 2]Fe Ga[(CH 2) 3N (CH 3) 2](R 1) ( 3a: R 1  C 2H 5; 3d: R 1  BH 4) exhibit FeGa bond lengths of 245.65(4) pm and 237.5(1) pm respectively. The GaB distance in 3d amounts to 237.4(3) pm. Remarkably pure Fe/Ga thin films were grown from 3d by low pressure OMCVD. The BH 4 group reduces both the decomposition temperature of the single source precursor and the degree of contamination by carbon of the mixed metal thin films.

Synthesis and characterization of novel organogallium-phosphorus compounds: x-ray crystal structures of [cyclic] Ph2GaP(SiMe3)2Ga(Ph)2Cl, Ph2(Cl)Ga.cntdot.P(SiMe3)3, and Ph3Ga.cntdot.P(SiMe3)3

Abstract : A Ga-P-Ga-Cl ring containing compound, Ph2GaP(SiMe3)2Ga(Ph)2C1 (1), is reported. Compound 1 is an example of a four-membered ring system with mixed bridging of the two gallium centers and was prepared via the reaction of Ph2GaCl with P(SiMe3)3 in a 2:1 mole ratio in either toluene or pentane. Curiously, 1 was originally isolated as a minor product (ca 5% yield) from the reaction of LiP(SiMe3)2 with Ph2GaCl in a 1: 1 mole ratio. X-ray crystallographic analyses shows the Ga-P-Ga-Cl ring of 1 to be non-planar. The reaction of Ph2GaCl and P(SiMe3)3 in a 1:1 mole ratio in either toluene or pentane yields Ph2(Cl)Ga. P(SiMe3)3 (2). Compound 3, Ph3Ga.P(SiMe3)3, was also originally isolated as a minor product (ca. 10%) from the reaction of LiP(SiMe3)2 with Ph2GaCl in a 1:1 mole ratio and is an additional reported example of an adduct formed through ligand redistribution involving LiE(SiMe3)2 (E = P or As) as a reactant. The straightforward synthesis of 3 can be accomplished by the 1:1 mole reaction of Ph3Ga and P(SiMe3)3 in pentane. Both 2 and 3 are structural examples of adducts containing a Ga-P bond with aryl ligands on the gallium center. Compound 1 belongs to the monoclinic system, space group P21/c, with z = 4, a = 10.579(2) Angstrom, b = 15.653(5) Angstrom, c = 20.428(4) Angstrom, and = 91.80(2)deg. Compound 2 crystallizes in an orthorhombic system, space group P212,21, with z 4, a = 9.3320(10) Angstrom, b = 9.768(2) Angstrom, and c = 30.581(6) Angstrom. Compound 3 belongs to the monoclinic system, space group P2,/n, with z = 4, a = 18.81(3) Angstrom, b = 19.25(2) Angstrom, c = 18.93(2) Angstrom, and beta = 112. 8(1)deg.

Organoerdmetallkomplexe von d-block-elementen

Abstract Carefully purified starting materials and precisely controlled stoichiometries guarantee high yield “one pot synthesis” of the novel volatile organogalliocobalt complexes 2–7 . These compounds are stabilized by intramolecular adduct formation at the gallium center. Synthesized compounds are identified by 1 H, 13 C, 31 P-NMR, infrared ν(CO) and MS data. A single crystal X-ray analysis of {μ-[3-(diethylamino)propyl]gallio}[bis(tetracarbonylcobalt)] reveals cobalt—gallium bond distances averaging to 254.3 pm. Thermal decarbonylation of 2–4 in the presence of phosphines, e.g. P(C 6 H 5 ) 3 , yields quantitatively the trans -phosphine substituted complexes 5–7 . In polar solvents those latter compounds exhibit a significantly weakened tendency towards heterolytic dissociation of the metal—metal bond. This behavior reflects a strengthened cobalt—gallium interaction, as it is also indicated by mass spectroscopy.

Synthetic and Structural Studies on Organotransition Metal‐Gallium Complexes

The transition metal‐gallium complexes [Ga(MLn)3] [where MLn=Fe(CO)2(η‐C5H5), Mo(CO)3(η‐C5H5), Co(CO)3(PPh3), and Mn(CO)5] have been synthesised by salt elimination between GaCl3 and MI(MLn) (MI=Na/K). The iron complex [Ga{Fe(CO)2(η‐C5H5)}3] (1) has been characterised by X‐ray crystallography and shown to contain a planar, three‐coordinate gallium centre bound to three Fe(CO)2(η‐C5H5) fragments by unsupported Ga–Fe bonds [av. 2.444(1) Å]. A partial structure determination of [Ga{Mo(CO)3(η‐C5H5)}3] (5) is consistent with a trigonal‐planar GaMo3 core. Brief mention is also made of two chloro complexes [GaCl(MLn)2] [MLn=Fe(CO)2(η‐C5‐H5) and Co(CO)3(PPh3)].

Modellsysteme für die Gallium-Extraktion, II / Model Systems for Gallium Extraction, II

The introduction of a methyl substituent in the 2-position of 8-oxy-quinoline strongly alters its ligand properties in the complex formation with gallium(III). From aqueous solutions (ammonium acetate buffer, acetic acid, gallium nitrate) a pale-green complex (2-MeOx)2GaOAc is precipitated instead of the tris(oxinate) chelate. According to a single crystal X-ray diffraction study, the gallium atom is pentacoordinate in this complex, with two chelating 2-MeOx and one monocoordinate acetate ligands. Similar acetato complexes were generated with equally hindered 2,4-dimethyl- and 2,5,7-trimethylquinoline, as well as with 2-ethyl- and 2-n-propylquinoline ligands. Retaining the 2-MeOx ligand, acetate OAc could be exchanged for trifluoroacetate, propionate, cyanoacetate, and (in binuclear complexes) equivalents of succinic, maleic, fumaric, and acetylenedicarboxylic acid. From this series, crystal and molecular structures have also been determined for (2-MeOx)2GaOC(O)CH2CN and [(2-MeOx)2GaOC(O)CHJ2]2 (with crystal nitrobenzene). In the cyanoacetate, the nitrile function is not involved in intra/intermolecular metal coordination. In the binuclear succinate the molecule has a crystallographical center of inversion. As in the cyanoacetate, the environment of the two equivalent gallium centers of the succinate is very similar to that of the acetate complex.

Synthesis and crystal structure of a mixed bis(arene)gallium(I) complex: Dimeric (η 6-1,2,4,5-tetramethylbenzene) (η 6-toluene)gallium(I) tetrachlorogallate(III)

The title compound (η 6-1,2,4,5-tetramethylbenzene)(η 6-toluene)gallium(I) tetrachlorogallate(III) ( 1) crystallizes from dilute solutions of equimolar quantities of gallium(I) tetrachlorogallate(III) and 1,2,4,5-tetramethylbenzene (durene) in toluene on slow cooling to 0°C. More concentrated solutions yield the 1 : 1 complex (1,2,4,5-C 6H 2Me 4)Ga +Ga Cl 4 − ( 2). The crystals of compound 1 contain centrosymmetrical dimers, {[(η 6-C 6H 2Me 4)(η 6-C 6H 5Me)Ga]GaCl 4} 2, in which each gallium(I) centre is hexahapto-bonded to one durene and one toluene molecule. The two aromatic hydrocarbons of these bent-sandwich moieties form an interplane angle of 58°. With a metal-to-ring distance of 2.642 Å, the durene ring is much closer to the Ga + atom than the toluene ring (3.039 Å). The Ga + atoms are bridged via two slightly distorted GaCl 4 − tetrahedra through contacts with three of the four chlorine atoms. The structure resembles that of the [(C 6H 6) 2Ga]GaX 4 complexes with X = Cl, Br.

Synthese und Kristallstruktur des Bis(benzol)gallium(I)-tetrabromogallat(III)-Dimeren / Synthesis and Crystal Structure of the Bis(benzene)gallium (I) Tetrabromogallate(III) Dimer

Anhydrous Ga[GaBr4] is readily dissolved in benzene. The resulting solutions show discrete 71Ga NMR signals for Ga(I) und Ga(III) centers. Narrow line-widths of the former indicate a small electric field gradient of the Ga(I) nucleus due to almost spherical shielding by the 4 s2 lone pair of electrons. Crystals obtained from the benzene solution on cooling have the stoichiometry [(C6H6)2Ga · GaBr4]2 ·3 C6H6, and are isomorphous with the analogous chloride compound: a = 9.390(2). b = 10.847(1), c = 13.118(2) Å; α = 85.54(1). β = 102.91(1). γ = 105.62(1)°; triclinic, space group Ρ1̄, Z = 1. The centrosymmetric dimers are composed of bis(benzene)gallium(I) and tetrabromogallate(III) units bridged by six bromine atoms. Only two bromine atoms are not engaged in coordinative bonding. The two benzene rings are both η6-bonded to the gallium(I) center, but not equidistant. They are enclined by 57.5°. The remaining benzene molecules are crystal benzene with no specific cation or anion contacts.

Optical properties of atomic gallium and indium centres in KCl

In radiation-damaged In- and Ga-doped KCl crystals many In- and Ga-related defects are formed. Their optical absorption bands strongly overlap, making it impossible to determine the optical transitions of a particular defect directly. With measurements of the magnetic circular dichroism tagged by electron spin resonance absorption bands of Ga0(1) and In0(1) centres, the analogues of the laser-active Tl0(1) centres, could be identified. Ga0(1) centres have absorption bands peaking at 930, 890 and 620 nm and In0(1) centres at 965, 860 and 610 nm. Up to 2.7 mu m no emission was found for Ga0(1) centres, whereas upon excitation at 965 nm In0(1) centres probably have a very weak emission around 2.2. mu m. In a model calculation the occurrence of radiative and non-radiative transitions upon excitation of the lowest excited state in Ga0(1), In0(1) and Tl0(1) centres is discussed.

ChemInform Abstract: GROUP 3 TETRAHYDROBORATES. PART 1. THE SYNTHESIS AND PROPERTIES OF DIMETHYLGALLIUM TETRAHYDROBORATE

AbstractDie Titelverbindung (I), die durch Umsetzung von Trimethyl‐Ga mit Diboran (Ausb. 20‐40%) oder von Dimethyl‐GaCl mit Li‐tetrahydridoborat (Ausb. 80%) erhältlich ist, wird durch Molgewichtsbestimmung, massen‐, schwingungsund NMR‐spektroskopische Daten charakterisiert.

Group 3 tetrahydroborates. Part 1. The synthesis and properties of dimethylgallium tetrahydroborate

The synthesis, characterization, and properties of Ga(BH4)Me2 are reported. Although first prepared via the interaction of GaMe3 and diborane, the compound is more satisfactorily prepared by the reaction of GaMe2Cl with Li[BH4] in the absence of a solvent at –15 °C. Subsequent characterization has been based on the vapour-phase molecular weight, on the mass, vibrational, and 1H n.m.r. spectra of the material, and on elemental analysis of the ammonia adduct Ga(BH4)Me2·2NH3. The i.r. spectrum of the gaseous tetrahydroborate is consistent with a molecular model Me2Ga(µ-H)2BH2 having C2v symmetry and containing four-co-ordinate gallium linked to a bi-dentate tetrahydroborate group; such a structure appears to persist in the condensed phases, although the vibra-tional spectra suggest increased polarization in the sense [GaMe2]+[BH4]–. Chemical studies have disclosed, inter alia, ready hydrogen–methyl exchange between the boron and gallium centres, as well as instances of symmetrical and unsymmetrical cleavage of the Ga(µ-H)2B skeleton.