FT-Raman spectroscopic analysis of the most probable structures in aluminum chloride and tetrahydrofuran solutions

New Vibrational Information on Simple Amides in Solution: A Case Study on GaCl3-Formamide Complexes

“…e spectral features related to the major complexes are shown in Figure 4, and their assignment is also made on the basis of n FA-Ga determined at the ] CO and ] CN regions. A closer look in the Raman spectrum of the most diluted salt solution reveals the presence of a 329 cm − 1 band (Figure 4(a)), whose position is practically identical to that reported for AlCl 3 .THF [21] and [AlCl 3 (THF) 3 ] [6]. is unique signal is then ascribed to the [GaCl 3 FA] complex not only by analogy with the former but also due to the good relationship with n FA-Ga .…”

“…where M � metal; m and n (≤3) vary as a function of the salt composition. Hence, [MCl 4 ] − is practically the major component in these solutions, as very well established by calorimetric and vibrational spectroscopic studies [3,6]. e abundance of this tetrahedral species seems to be dependent not only on the kind of metal ion but also on the nature of the solvent.…”

“…Since the spectral changes observed at the solvent region are consistent with the coordination phenomenon, it would be now advisable to determine the average number of FA molecules around Ga 3+ (n FA-Ga ) in order to obtain information on the geometry of the complexes, which is a key stage for the calculation of the ϕ values. For doing this, both ] CO and ] CN regions were employed and due to the good relationship between the non-coordinated amide bands, and the salt content, n FA-Ga was determined following the equation [6][7][8][10][11][12][13][14][15]:…”

“…Both Raman and IR spectra were obtained with 4 cm − 1 resolution at the temperature of 20 ± 2°C. OMNIC 7.3 software was employed for the spectral data treatment, and details can be found in our previous works [6][7][8][10][11][12][13][14][15].…”

“…− , is present in the Raman spectra of AlCl 3 -tetrahydrofuran (THF) solutions at room temperature [6], but no signal can be detected at this region as the ether is replaced by formamide (FA) [7]. On the contrary, FeCl 3 -FA solutions show the arising of the 332 cm − 1 band, which is due to A 1 vibration of [FeCl 4 ] − [8].…”