Gallium halide

Gallium Halides.—NH4GaF4-NH4AlF4 and y-GaF3-y-AlF3 both form continuous series of solid solutions, with linear relationships between composition and lattice constants.533 

The vibrational spectra of GaX3,H20 (X = Cl or Br) can be assigned in terms of the local symmetry of GaX30 (C3v) and HaO (C2 ) rather than the overall symmetry of the adducts (Cs).535 

An improved synthesis of BunnGaCl3 n (n = 1—3) has been reported.537 This is a simple metathetical reaction, in a hydrocarbon solvent  

Vibrational assignments have been made for NO+GaCL, prepared by the reaction of NOC1+ GaCl3 in a variety of solvents, or by dissolving Ga metal in NOCl.538 A comparison of the spectra of crystalline NO+GaCl4 with that of the A1 analogue shows that they are closely related structurally. 

Series of mixed-halide complexes of Ga11, i.e. Ga2XnY6 n, where X-Cl, Y = Br or I X = Br, Y = I n = 1—5, are present in mixtures of Ga2X and Y in MeN02 solution.539 Individual members cannot be isolated, but vibrational spectroscopic data could be obtained by examining solutions 

Gallium Halides.—GaFgjSHgO may be prepared in 93—96% yield by dissolving Ga in a mixture of 40% HF and 30% 

Mass spectrometric measurements have been used to determine the vapour pressures of GaFa and (GaFg)2. Calculations of the enthalpies and entropies of sublimation gave the following results GaFg (298 K) 58.8  

Chemical analysis and i.r. spectra of the hydrolysis products of the ammine adducts of GaF3,3NHa and InF3,3NH3 show that they are ammonium di-hydroxotrifluoro-gallate and -indate, respectively, and not hydrated ammines of the corresponding fluorides.  

The rate parameters for exchange of Cl with GaCl in concentrated aqueous HCI have been obtained by C1 n.m.r. the enthalpy and entropy of activation were calculated (A T = 30.1 1.5 kJ mol A5 = —24 6 Jmol-iK-i). 8  

A partial assignment has been proposed for the i.r. absorptions of mixed gallium halide complexes [GaXgY] (X, Y = Cl, Br, or I) see Table 2.  

LiMnGaF crystallizes with the Na2SiF6 structure, being trigonal, and belonging 

Chloride-exchange processes in Ga species in concentrated aqueous chloride solutions were studied using Cl and Ga n.m.r. The results may be rationalized in terms of an associative exchange of CF at GaQ. Values were obtained for the enthalpy and entropy of activation.  

A systematic study of the formation of complex chlorides in binary systems containing MCI3 (M = Ga or In) or InCl has been made.  

The Raman spectra of GaClgBr and GaBr3CF have been obtained. They can be analysed assuming 3 symmetry for the ions (Table 12). They were produced by mixing methanolic solutions of GaCl3 or GaBr3 with the appropriate R4E X salt.  

Solutions of the gallium halides (Cl, Br, or I) in acetonitrile, benzene, or nitromethane, together with some binary solvent mixtures, have been investigated by Ga, Ga, and H n.m.r. spectroscopy. A major conclusion is that the solvation numbers of the Ga ion increase on passing from chloride to iodide in 

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Several gallium halide derivatives of the -C6H3-2,6-Mes2 ligand have been synthesized. The first of these was the compound ClGa(C6H3-2,6-Mes2)275... 

The formation of molecular complexes between aluminum trihalides and pyridine or alkylpyridines has been the subject of systematic studies.35,36 Calorimetric data yield bond dissociation energies D(X3Al—py) of 323, 308 and 264 kJ mol-1 for X = C1, Br and I, respectively, and this same order is found for alkylpyridine adducts, although the A1—N bond is weakened in the case of lutidine by the effects of steric hindrance. For gallium halides the values of D(X3M—py) are smaller 248, 237 and 195 kJ mol-1 for chloride, bromide and iodide adducts, respectively. 

The trUialides (except the fluorides) all function as Lewis acids, forming 1 1 adducts with a great variety of Lewis bases. This is one of the most important aspects of the chemistry of the gallium halides. The Lewis acidity of the GaXs groups has been extensively studied thermodynamically, and basicity sequences for a variety of donors have been established. 

Various values for zlHm are also obtained by appl3dng the second postulate to GaCl3 (21.8 kcal), GaBrs (8.3 kcal) and Gals (—0.3 kcal). Application of the second postulate to gallium halides is obviously not correct the value of — 0.3 kcal is certainly too small and hence the same applies to zip. 

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