The Crystal structures of tetra-n-Butylammonium salts of GaCl₄⁻, GaBr₄⁻ and GaI₄⁻

ISSN： 0095-8972

Source： Journal of Coordination Chemistry, Vol.56, Iss.18, 2003-12, pp. : 1567-1574

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Abstract

Tetra-n-butylammonium salts of Ga, Ga and have been prepared from stoichiometric amounts of GaX₃ and Bu₄NX in methanol. Their crystal structures have been determined by single crystal X-ray diffraction. The Bu₄N[GaCl₄] and Bu₄N[GaBr₄] salts crystallize in the orthorhombic system, space group Pnna, whereas the Bu₄N[GaI₄] salt crystallizes in the monoclinic system, space group P2₁/n. For all compounds there are four molecules per unit cell. The structures consist of distorted tetrahedral ions and Bu₄N⁺ cations. In the tetrahedral Ga and Ga anions there are two pairs of Ga-X distances: 2.163(2), 2.174(2) Å and 2.297(2), 2.316(3) Å, respectively. In the ion there are four Ga-I distances: 2.537(2), 2.539(2), 2.549(2) and 2.554(2) Å. The results show that the significantly greater increase in Ga-X distance on passing from Br to I than from Cl to Br results in lower symmetry and is accompanied by greater distortion of the tetrahedron.