Matrix-isolation studies on metal coordinated oxyanions. The shape of molecular MClO4, MClO3, MReO4, and EuWO4 systems

Abstract

Alkali-metal perchlorates (MClO4), chlorates (MClO3), perrhenates (MReO4), and EuWO4 were investigated with the aid of matrix-isolation IR spectroscopy. The Raman spectra of the MClO4 and MReO4 molecules were also measured in inert matrices. 18O-substitution experiments were carried out on Li 35ClO4, K 35ClO4, Cs 35ClO3, KReO4, and EuWO4 in order to provide the assignment of the observed spectra and to establish the molecular structure of these molecules in the vapor phase. These experiments indicate a C2v bidentate structure for all the MXO4 molecules. The ClO−4 and ReO−4 anions are slightly distorted tetrahedrons with bond angles close to 109°. The WO=4 anion is a distorted tetrahedron with the OWO bond angles equal to 86° and 109°. Alkali chlorates MClO3 are species of C3v symmetry with the metal cation placed on the C3 axis of the ClO−3 pyramidal anion.

Molecular dynamics simulation of molten sodium chlorate

“…Molten alkali chlorates have been used as medium in synthesising processes such as the production of Al-Ti-B alloys, 15 the oxidation of UO 2 , 16 and in preparing lead magnesium niobate powders. 21,22 Since infrared and Raman spectra of alkali chlorates have been reported, [20][21][22][23][24] these ab initio calculations were devoted to the calculation of vibrational frequencies. 18 Fundamental properties of molten chlorates, such as thermodynamic data, ionic conductivity, and viscosity, are known.…”

Matrix isolation studies and DFT calculations on molecular alkali metal bromates

“…6,8 The initial calculations were carried out on molecular bromates MBrO 3 (M = Na, K, Rb, Cs) using MP2 and B3LYP 9 methods, and were subsequently extended also to CsClO 3 and CsIO 3 for comparison with published experimental data. [3][4][5][6] The basis sets employed here were: aug-cc-pvtz for Br, Cl, Na and O; cc-pvtz -PP for I; 10 and Stuttgart '97 RSC ECP for K, Rb and Cs. 11 Vibrational frequencies were estimated according to harmonic approximations and were left unscaled.…”

“…The above results show that the B3LYP method is very successful in mirroring the observed IR spectrum of the BrO 3 moiety in molecular CsBrO 3 , and it is of some interest to establish whether similar calculations are able satisfactorily to reproduce the vibration frequencies of other MXO 3 molecules. Both calculation methods were therefore applied to the related molecular species CsIO 3 and CsClO 3 , for which previous matrix isolation studies [3][4][5][6] have established assignments for the four ''anion'' modes within the C 3v tridentate structure. Table 3 compares the published argon matrix data for CsClO 3 and CsIO 3 with the calculations carried out here using MP2 and B3LYP methods.…”

“…Alkali metal bromates are generally encountered as stable salts having well-established structures, 1 but although a number of studies have been carried out on their thermal decomposition, 2 there appear to have been no serious attempts to investigate the composition of the high temperature vapor, or more specifically, to search for molecular bromates. For the analogous chlorates and iodates, matrix isolation studies [3][4][5][6] have convincingly demonstrated that molecular MXO 3 species are formed on vaporisation, and have established their structures as being based on C 3v symmetry with tridentate cation coordination.…”

Infrared multiple photon dissociation spectroscopy of sodium and potassium chlorate anions

“…The structures and bonding characteristics of contact ion pairs such as metal nitrates, chlorates and perchlorates have been the subject of a number of experimental and theoretical studies 1–12. To date, the principal experimental method for investigating the vibrational spectroscopy of these species as discrete entities has been matrix isolation infrared absorption (MI‐IR), which has revealed preferred coordination mode(s) by the respective anions (i.e.…”