Resonance Raman spectra of inorganic salt vapors I. Palladium (II) and Copper(II) chloroaluminates

Abstract

Resonance Raman spectra of vapor molecules formed by reacting gaseous aluminum chloride with solid PdCl2 and CuCl2 have been measured in the temperature range from 500 to 900 K and at total pressures up to 30 atm. The main features of the Raman spectra of the Pd–Al–Cl gaseous molecule are three polarized bands at 298, 176, and 84.5 cm−1. The excitation profiles of these bands exhibit minima in the vicinity of the maximum Pd(II) ligand field absorption, thus suggesting the presence of a center of symmetry in the molecule. A D2h molecular symmetry is proposed for the PdAl2Cl8 vapor complex having Pd(II) as a central atom in square planar coordination. The Raman spectra of the Cu–Al–Cl vapors are interpreted to account for two different molecular species. Three polarized bands at 281, 174.5, and 84.5 cm−1 are assigned to preresonance enhanced A1 fundamentals of the CuAl2Cl8 molecule. Two strong bands at 448 and 291.5 cm−1 and their combinations and ovetones are assigned to resonance enhanced A1 fundamentals of the CuAlCl5 molecule having the Cu(II) in a trigonal coordination. Raman band intensity measurements using different laser line intensities suggest an increasing spectroscopic temperature and decomposition of the complex: CuAl2Cl8(g) →CuAlCl5(g)+AlCl3(g).

Solubilities, Structures, and Speciations of Bimetallic Composite Ionic Liquids: X-ray Absorption Fine Structure and Density Functional Theory Calculations

“…Many researchers tried to elucidate the species and structures for chloroaluminate-based bimetallic complexes in crystal, molten salt, and gaseous systems by various means, including Raman spectra, , UV–vis spectra, single crystal structure X-ray diffraction, and magnetic angle spinning nuclear magnetic resonance (MAS NMR) . However, figuring out the speciation and structures of the composite complex was difficult in bimetallic composite ILs.…”

Synthesis and Crystal Structures of New Palladium(II)—Gallium(III) Complexes with Bridging Halogenide Ligands

“…The existence of vapour phase complexes PdAl 2 X 8 , where X Ϫ ϭ Cl Ϫ , Br Ϫ , was described by Papatheodorou [3,4]. On the basis of Raman spectra, electronic absorption spectra and magnetic properties of these compounds a square-planar coordination of palladium has been proposed [5,6]. Subsequently, only one complex, Pd[AlCl 4 ] 2 , has been structurally characterized [7] among complexes of the general formulae Pd[MX 4 ] 2 (where M ϭ Al, Ga, In; X Ϫ ϭ Cl Ϫ , Br Ϫ , I Ϫ ).…”

Soft Bending Modes of Terminal Chlorides in Gaseous Two- and Three-Coordinate Cu(II)−Cl Species

“…This leads to a multitude of gas-phase complexes, among them CuAlCl 5 and CuGaCl 5 which are included in this work. Papatheodorou and Capote 14 proved the existence of CuAlCl 5 by means of resonance Raman spectroscopy and suggested a C 2V ring structure with threecoordinate copper and four-coordinate aluminum. Schla ¨pfer and Rohrbasser 15 have observed CuGaCl 5 in their resonance Raman spectra, but assigned all of its bands to CuGa 2 Cl 8 .…”