The structure and vibrational spectra of gallium(III) fluoride dimeric complex with tetramethylammonium cation

We have determined the crystal structure of gallium(III) fluoride dimeric complex [N(CH$_3$)$_4$]$_{2}$[Ga$_{2}$F$_{8}$(H$_{2}$O)$_{2}$], which is composed of [N(CH$_3$)$_4$]$^{+}$ tetrahedral cations and [Ga$_{2}$F$_{8}$(H$_{2}$O)$_2$]$^{2-}$ – dimeric complex anions, formed by combining two slightly distorted GaF$_{5}$(H$_{2}$O) octahedral groups with a common F–F edge. By O–H$\cdots$F hydrogen bonds, [Ga$_{2}$F$_{8}$(H$_{2}$O)$_2$]$^{2-}$ dimeric complex anions unite into polymer chains, between which tetramethylammonium cations are located. Based on quantum-chemical calculations, we have assigned bands in vibrational spectra of the synthesized compound. Bands that refer to vibrations of anions, cations and H$_2$O molecules involved in hydrogen bonds have been identified in the spectra.