Aluminum Analogue Research Articles

The molecular geometry of the addition compound Cl 3Ga.NH 3 as studied by electron diffraction

The molecular geometry of the complex of gallium trichloride with ammonia, Cl 3Ga.NH 3, has been studied by electron diffraction. The most important internuclear distances in terms of r a parameters are as follows: r(Ga-Cl) = 2.142±0.005Å, r(Ga-N) = 2.057±0.011Å, r(Cl⋯Cl) = 3.642±0.010Åand r(Cl⋯N) = 3.242±0.012Å. As in the case of the aluminium analogue, the flat pyramidal configuration of the GaCl 3 part of the complex suggests a planar equilibrium structure for free GaCl 3. The distance between the donor and acceptor parts may indicate a somewhat weaker interaction than is the case in the aluminium analogue.

The thermal decomposition of ammonium hexafluorogallate and ammonium hexafluoroindate. New crystalline forms of gallium fluoride and indium fluoride

Ammonium hexafluorogallate, (NH4)3GaF6, and ammonium hexafluoroindate, (NH4)3InF6, occur in two polymorphic forms, a low temperature tetragonal and a high temperature cubic form, which transform reversibly. They decompose on heating with an initial loss of 2 moles of ammonium fluoride, forming ammonium tetrafluorogaIlate, NH4GaF4, and ammonium tetra fluoroindate, NH4InF4. Further heating results in the gradual loss of ammonium fluoride; the final decomposition products are γ-gallium fluoride and γ-indium fluoride, new crystalline forms. These convert on further heating to the common hexagonal forms of the trifluorides. The structural relationship of the compounds are discussed and compared with those of the aluminum analogs.

Reactions between organogallium compounds and nitriles

The systems RCN–GaR3′(R = Me, Ph, or But; R′= Me or Et) and Cl3CCN–GaMe3 have been studied, and the new adducts PhCN,GaMe3; ButCN,GaMe3; MeCN,GaEt3; PhCN,GaEt3; and ButCN,GaEt3 prepared and characterised. All tend to dissociate into the components under reduced pressure, particularly when heated gently, but when heated in closed vessels MeCN,GaMe3 gives methane and polymers, PhCN,GaMe3 gives 2,4,6-triphenyltriazine Ph3C3N3, and PhCN,GaEt3 and ButCN,GaEt3 lose ethylene to form the azomethine derivatives (PhCH:N·GaEt2)2 and (ButCH:N·GaEt2)2, respectively. Features of the infrared spectra of these compounds are discussed, and when compared with those of their boron and aluminium analogues provide further evidence that the acceptor properties of organo-derivatives of Group III elements decrease in the sequence R3Al > R3Ga > R3B.

ON OSARIZAWAITE, A NEW MINERAL OF THE ALUNITE GROUP. FROM THE OSARIZAWA MINE, JAPAN

Osarizawaite, a new mineral. from the Osarizawa mine occurs in the oxidized zone of lead-zinc-copper veins as earthy and friable masses, associated with other secondary minerals of lead or copper. The chemical formula of osarizawaite has been determined as Pb (Cu0.98 Zn0.02) (Al0.81 Fe0.1 ?? )2 (SO4)2 (OH)6. Its physical and optical properties are: greenish-yellow in colour; specific gravity=3.89-4.02, 4.20 (calc.); mean index of refraction=1.735-1.757, birefringence strong. The unit cell dimensions for both the hexagonal cell and the corresponding rhombohedral cell are: α0=7.05Å., c0=17.23Å., Z=3; αrh=7.04Å., α=60°06′, Z=1. The data obtained demonstrate that the mineral is a new species being the aluminum analogue of beaverite and belongs to the alunite group. A new mineral name, osarizawaite, is proposed for the mineral which belongs to the alunite group and whose ideal chemical formula is PbCuAl2(SO4)2(OH)6 where Cu and Al may be partially replaced by Zn and Fe respectively.