The structure of solutions of gallium(I) chloride in benzene

Abstract

The structure of benzene solutions of Ga[GaCl₄] and Ga[Ga₂Cl₇] has been investigated by ¹³C and ⁷¹Ga NMR, Raman spectroscopy and liquid X-ray scattering (LXS). Assignments of the vibrational spectra are based on a reinvestigation of the liquid Ga–GaCl₃ system. The results for the Ga[GaCl₄]–C₆H₆ system are in agreement with the view that an ion pair between Ga⁺ and GaCl₄^–, which lowers the symmetry of the GaCl₄^– ion from T_d to C_2v or lower, is formed. Spectroscopic effects indicating a complex formation between Ga⁺ and benzene are weak. The salt Ga[Ga₂Cl₇] was found to be extremely soluble in benzene ( >50% w/w). The results imply that in such solutions the Ga–Cl_b–Ga bridge in the Ga₂Cl₇^– ion is bent and the ion pairing between Ga⁺ and Ga₂Cl₇^– takes place via the bridging chloride ion of the latter ion. Results from LXS show that the Ga^III-Cl_b distance is remarkably long, 2.85 Å(24% longer than in solid K[Ga₂Cl₇]). For this system, ⁷¹Ga and ¹³C NMR as well as Raman spectroscopic results clearly indicate complex formation between Ga¹ and benzene.