The high covalence of metal-ligand bonds as stability limiting factor: the case of Rh(IX)O4+ and Rh(IX)NO3

“Semi-Long-Periodical” Tabulated Version of Chemical Elements Periodic System

A possible modification of the tabulated version of the Chemical Elements Periodical System, proposed to overcome deficiencies of the two most used versions—the “short-periodical” proposed by Mendeleev and the “long-periodical” introduced by Werner and recommended by IUPAC at the present time—is discussed in this paper.

The Highest Oxidation State of Rhodium: Rhodium(VII) in [RhO3 ]. Angew Chem Int Ed Engl 2022;61:e202207688. [PMID: 35818987 PMCID: PMC9544489 DOI: 10.1002/anie.202207688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Although the highest possible oxidation states of all transition elements are rare, they are not only of fundamental interest but also relevant as potentially strong oxidizing agents. In general, the highest oxidation states are found in the electron-rich late transition elements of groups 7-9 of the periodic table. Rhodium is the first element of the 4d transition metal series for which the highest known oxidation state does not equal its group number of 9, but reaches only a significantly lower value of +6 in exceptional cases. Higher oxidation states of rhodium have remained elusive so far. In a combined mass spectrometry, X-ray absorption spectroscopy, and quantum-chemical study of gas-phaseR h O n + (n=1-4), we identifyR h O 3 + as the1 A 1 ' trioxidorhodium(VII) cation, the first chemical species to contain rhodium in the +7 oxidation state, which is the third-highest oxidation state experimentally verified among all elements in the periodic table.

Impact of substituent nature in diformylpyridyl Schiff base on photophysical and electrochemical properties of ruthenium- and iron-based complexes

The effect of substituents on the optical properties, redox potential, and reorganization energy in a series of Ru and Fe based complexes was studied. All studied complexes respond to the requirements for a sensitizer as the main component of DSSC.

Fluoro Nitrenoid Complexes FN=MF2 (M=Co, Rh, Ir): Electronic Structure Dichotomy and Formation of Nitrido Fluorides N≡MF3

The fluoronitrenoid metal complexes FNCoF2 and FNRhF2 as well as the first ternary RhVI and IrVI complexes NIrF3 and NRhF3 are described. They were obtained by the reaction of excited Group-9 metal atoms with NF3 and their IR spectra, isolated in solid rare gases (neon and argon), were recorded. Aided by the observed 14/15 N isotope shifts and quantum-chemical predictions, all four stretching fundamentals of the novel complexes were safely assigned. The F-N stretching frequencies of the fluoronitrenoid complexes FNCoF2 (1056.8 cm-1 ) and FNRhF2 (872.6 cm-1 ) are very different and their N-M bonds vary greatly. In FNCoF2 , the FN ligand is singly bonded to Co and bears considerable iminyl/nitrene radical character, while the N-Rh bond in FNRhF2 is a strong double bond with comparatively strong σ- and π-bonds. The anticipated rearrangement of FNCoF2 to the nitrido CoVI complex is predicted to be endothermic and was not observed.

Theoretical study of rhodium(III)-catalyzed synthesis of benzoxepine and coumarin

The mechanisms of the rhodium-catalyzed cycloaddition of 2-vinylphenol with diphenylacetylene and carbon monoxide have been studied using density functional theory calculations at the B3LYP/6-31G (d, p) (Lanl2dz for Rh) level of theory. The SMD solvation model was used in MeCN solvents at M06-2X/6-311 ++ G (d, p) (Lanl2dz (f) for Rh) levels using a single-point calculation to consider the solvent effect. The calculation results show that there are two competitive reaction pathways for the cycloaddition reaction of rhodium-catalyzed synthesis of benzohexine and coumarin. Starting from the precursor reaction complex, the reaction channel is more favorable for the carbon atoms of diphenylacetylene and carbon monoxide to attack the Rh-C bond (the barriers of 9.88 and 10.01 kcal/mol) rather than attack the Rh-O bond (the barriers of 15.37 and 30.17 kcal/mol), and carbon monoxide in two different reaction channels has a greater energy difference than diphenylacetylene. The results show that the computational study of the rhodium-catalyzed cycloaddition reaction has a high catalytic activity consistent with the high yield of the experiment of Gulías et al.