title: Molecular CsF5 and CsF2+.
abstract: D5h star-like CsF5 , formally isoelectronic with known XeF5 (-) ion, is computed to be a local minimum on the potential energy surface of CsF5 , surrounded by reasonably large activation energies for its exothermic decomposition to CsF+2 F2 , or to CsF3  (three isomeric forms)+F2 , or for rearrangement to a significantly more stable isomer, a classical Cs(+) complex of F5 (-) . Similarly the CsF2 (+) ion is computed to be metastable in two isomeric forms. In the more symmetrical structures of these molecules there is definite involvement in bonding of the formally core 5p levels of Cs.
authors.affiliation: Dept. of Biological and Chemical Sciences, Illinois Institute of Technology (USA).
authors.forename: Andrey Yu
authors.initials: AY
authors.lastname: Rogachev
authors.affiliation: Department of Chemistry and Biochemistry, California State University Northridge (USA).|Beijing Computational Science Research Center (P.R. China).
authors.forename: Mao-Sheng
authors.initials: MS
authors.lastname: Miao
authors.affiliation: Departamento de Física Aplicada, Centro de Investigación y de Estudios Avanzados, Unidad Mérida (México).
authors.forename: Gabriel
authors.initials: G
authors.lastname: Merino
authors.affiliation: Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca NY 14853-1301 (USA). rh34@cornell.edu.
authors.forename: Roald
authors.initials: R
authors.lastname: Hoffmann
mesh_terms: D002586:Cesium / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D008958:Models, Molecular
chemical_list: D002586:Cesium; D005459:Fluorides
keywords: breaking into cores; cesium; fluorides; polyfluoride anions; quantum chemistry