title: How far can we go? Quantum-chemical investigations of oxidation state +IX.
abstract: The highest known oxidation state of any element is +VIII. After the recent discovery of Ir(VIII)O(4) under cryogenic conditions, we have investigated the stability of cationic species [MO(4)](+) (M=Rh,Ir,Mt). Such compounds would formally represent the new oxidation state +IX, which is experimentally unknown so far for the whole periodic table. [IrO(4)](+) is predicted to be the most promising candidate. The calculated spin-orbit (SO) coupling shows only minor effects on the stability of the iridium species, whereas SO-coupling increases enormously for the corresponding Eka-Iridium (Meitnerium) complexes and destabilizes these.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Albert-Ludwigs Universität Freiburg, Albertstrasse 21, D-79104 Freiburg i. Br., Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Himmel
authors.forename: Carsten
authors.initials: C
authors.lastname: Knapp
authors.forename: Michael
authors.initials: M
authors.lastname: Patzschke
authors.forename: Sebastian
authors.initials: S
authors.lastname: Riedel