Die formalen Oxidationszahlen des Iridiums reichen nun von −III bis +IX

The chemistry of lanthanides (Ln=La–Lu) is dominated by the low‐valent +3 or +2 oxidation state because of the chemical inertness of the valence 4f electrons. The highest known oxidation state of the whole lanthanide series is +4 for Ce, Pr, Nd, Tb, and Dy. We report the formation of the lanthanide oxide species PrO4 and PrO2+ complexes in the gas phase and in a solid noble‐gas matrix. Combined infrared spectroscopic and advanced quantum chemistry studies show that these species have the unprecedented PrV oxidation state, thus demonstrating that the pentavalent state is viable for lanthanide elements in a suitable coordination environment.

Pentavalent Lanthanide Compounds: Formation and Characterization of Praseodymium(V) Oxides

Zhang

et al. 2016

Oxidation State 10 Exists

Truhlar

2016

In a recent paper, Wang et al. found an iridiumcontaining compound with a formal oxidation state of 9. [5] This is the highest oxidation state ever found in a stable compound. To learn if this is the highest chemical oxidation state possible, Kohn-Sham density functional theory was used to study various compounds, including PdO 4 2+ , PtO 4 2+ , PtO 3 F 2 2+ , PtO 4 OH + , PtO 5 , and PtO 4 SH + , in which the metal has an oxidation state of 10. It was found that PtO 4 2+ has a metastable state that is kinetically stable with a barrier height for decomposition of 31 kcal mol À1 and a calculated lifetime of 0.9 years. All other compounds studied would readily decompose to lower oxidation states.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.

Über Oxidationszahl‐Obergrenzen in der Chemie

et al. 2018

The concept of oxidation state OS is based on the Lewis electron-pair picture, assigning all bonding electrons to the more electronegative element. It is useful for bookkeeping the electrons, predicting chemical trends and inspiring synthetic chemists. A survey of experimental and quantum-chemical data reveals a limit near +8 for the highest OS in stable neutral chemical compounds under ambient conditions. OS = +9 was observed for isolated [IrO4] + cations in vacuum. The predicted existence of OS = +10 in a Pt compound is still to be verified experimentally. A high OS may involve the metal becoming electronegative and the O −2 ligands losing their closed-shell character as O −1 .