Structure and vibrational spectra of the vapour molecules Fe2Cb and AlFeCl6

Citation
Z. Akdeniz et Mp. Tosi, Structure and vibrational spectra of the vapour molecules Fe2Cb and AlFeCl6, Z NATURFO A, 54(8-9), 1999, pp. 477-481
Citations number
25
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES
ISSN journal
09320784 → ACNP
Volume
54
Issue
8-9
Year of publication
1999
Pages
477 - 481
Database
ISI
SICI code
0932-0784(199908/09)54:8-9<477:SAVSOT>2.0.ZU;2-J
Abstract
Melting of aluminium and iron trichloride crystals is accompanied by a stru ctural transition from octahedral to tetrahedral coordination of the metal ions, and a widely accepted interpretation of their liquid structure is tha t it mainly consists of strongly correlated dimeric units. Such Al2Cl6 and Fe2Cl6 molecules are stable in the vapour phase and coexist in gaseous mixt ures together with AlFeCl6 molecules. In this work we extend to Fe2Cl6 and AlFeCl6 our earlier study of the ionic interactions in Al2Cl6 [Z. Akdeniz a nd M. P Tosi, Z. Naturforsch. 54a, 180 (1999)], using a model which account s for ionic deformability through (i) effective valences and (ii) electrost atic and overlap polarizabilities. The main disposable parameters of the mo del are adjusted to the Fe-Cl bond length in FeCl3 monomer molecule and to the Fe-Fe bond length and a bond-stretching frequency in the Fe2Cl6 molecul e. The results are used to evaluate the structure of the AlFeCl6 molecule, which has so far only been inferred from the observed Raman spectrum in mix ed vapours. Extensive comparisons with data on molecular vibrational freque ncies are also presented for Fe2Cl6 and AlFeCl6.