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The infrared and raman spectra of tetramethylammonium hexa-fluorophosphate, (CH3)4NPF6, and tetramethylammonium hexa-fluoroantimonate, (CH3)4NSbF6

1983; Pergamon Press; Volume: 39; Issue: 7 Linguagem: Inglês

10.1016/0584-8539(83)80032-4

1873-3824

A.M. Heyns, W.H.J. de Beer,

Solid-state spectroscopy and crystallography

The powder diffraction pattern of (CH3)4NSbF6 has been obtained and can be indexed on the basis of a primitive tetragonal unit cell. It is therefore very likely that (CH3)4NSbF6 is isostructural with (CH3)4NPF6 which belongs to the space group P4/nmm-D74h. The vibrational spectra of these two compounds were recorded over a wide temperature range and are discussed in relation to the above-mentioned crystal structure as well as the spectra of other (CH3)4N+-compounds. The vibrational bands of the cations in these salts show that they are only slightly distorted and weakly hydrogen-bonded to the respective anions. The spectra of the anions can be interpreted in terms of ordered groups showing the predicted splittings of bands. An approximately linear correlation is found between the translational lattice modes observed in the i.r. spectra and the reduced masses of a number of isostructural (CH3)4N+ compounds while the A2 u.-Eu. splitting of these modes decreases as the strength of hydrogen bonding in the crystal decreases.