| Abstract
| - Electronic structures, charge distributions, geometries, valenceforce constants, and vibrational frequencies of thehomoatomic clusters F3+,Cl3+, Br3+, andI3+ and of the heteroatomic clustersClF2+, BrF2+,IF2+, BrCl2+,ICl2+,and IBr2+ were determined. Theself-consistent field approach extended by MP2-correlation energy ordensity-functional corrections was applied using various basis sets. It wasfound that d- and f-type polarization functionsplay a crucial role as in some other halogen compounds. The MP2approach yields the most satisfactory results.The effect of the crystalline environment surrounding theCl3+, Br3+, andI3+ species is successfully simulatedbya Madelung potential. Frequencies calculated in the crystal fieldare in reasonable agreement with the morereliable ones among the experimental results. Coupling forceconstants were determined. They are not consistentwith some empirical rules. Bonding and charge distributions of theformally mixed-valence systemsX+Y20 arediscussed. X+ behaves like a divalent chalcogen withhigh electronegativity. Each of the X+−Y bonds inXY2+is very similar to the bond in X−Y. We predict theexperimentally unknown F3+ to be stable invacuum but notin the solid state. Structures and frequencies ofXY2+ species, which are as yet unknown, arealso predicted.
- Electronic structures, chargedistributions, geometries, valence force constants, and vibrationalfrequencies of homoatomic clusters F3+,Cl3+, Br3+, andI3+ in vacuum and in the crystal fields andof heteroatomic clusters ClF2+,BrF2+, IF2+,BrCl2+, ICl2+, andIBr2+ have been determined at the MP2 levelof theory. Polarization functions are indispensable for describingthe p−p−σ-bonded species. In many cases our theoreticalresults corroborate experimental data. In the other cases wepredict in which ranges the correct values shouldbe.
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