Abstract Because of the general interest in the bonding in noble gas (Ng) compounds and the lack of experimental data coupled with large discrepancies, reliable theoretical calculations are very important for the prediction of their structures and thermodynamics. We describe an approach for the prediction of heats of formation to ±1 kcal mol−1(chemical accuracy) based on molecular orbital theory level using coupled cluster (CCSD(T), coupled cluster with single and double excitations plus a perturbative triples correction) theory extrapolated to the complete basis set (CBS) limit with the correlation‐consistent basis sets including relativistic effective core potentials (RECPs). Additional corrections to the valence correlation energies include core–valence (CV) correlation, molecular scalar relativistic corrections, atomic spin–orbit corrections, and zero‐point vibrational energies. Applications of this approach for the determination of the structure of XeF6, the heats of formation of the xenon fluorides and krypton fluorides, and the methyl cation affinities (MCAs) of the Ngs are described. XeF6is predicted to have C3vsymmetry only at the highest computational levels. The experimental heats of formation of XeF4and XeF6require significant revision. The predicted heats of formation for KrF4and KrF6show that it will be extremely difficult to synthesize these compounds. The calculations show that there are serious issues with the experimental MCAs of all of the Ngs except for Ne.

Abstract Iron–sulfur proteins contain iron coordinated by at least one sulfur ligand and include proteins with mononuclear Fe centers with partial or complete cysteinyl sulfur ligation as well as proteins containing clusters of iron and inorganic sulfide. This review summarizes the structural, electronic, and redox properties of protein‐bound mononuclear FeS centers and FeS clusters containing [2Fe2S], [3Fe4S], and [4Fe4S] cores. In addition to the ubiquitous role in mediating biological electron transport, the roles of FeS centers have proliferated to include coupling of electron and proton transfer, substrate binding and activation, determining protein structure, regulation of gene expression and enzymatic activity, disulfide reduction, and iron, electron, or cluster storage. The diverse roles of FeS clusters are illustrated by discussion of specific systems: the mitochondrial and photosynthetic electron transport chains and a wide range of soluble redox enzymes and proteins; the active sites of nitrile hydratase, aconitase‐type (de)hydratases, superoxide reductase (SOR), radical‐SAM (S‐adenosylmethionine) enzymes, NiFe‐ and Fe‐hydrogenase, sulfite and nitrite reductase, nitrogenase, CO dehydrogenase, and acetyl‐CoA synthase; the structural FeS centers in DNA repair enzymes; the regulatory roles of FeS centers in the SoxR, fumarate–nitrate reduction (FNR), IscR/SufR, and iron‐regulatory protein (IRP) proteins and in selected enzymes; the two classes of FeS cluster containing disulfide reductases typified by ferredoxin–thioredoxin reductase (FTR) and heterodisulfide reductase (HDR); and the role of 8Fe ferredoxins and polyferredoxins in iron, electron, or cluster storage.

Abstract32P and33P are important radionuclides of phosphorus with half‐lives of 14.3 and 25.3 days, respectively, and which decay via β−emission. These isotopes (of 23 known) have anthropogenic sources and are prepared by the enrichment of sulfur. The radionuclides are used in tracer studies primarily as phosphate, or other common phosphate forms such as “phosphate rock” or ortho‐phosphoric acid. Various labeling and therapeutic studies have been performed in the fields of biology, botany, and in clinical medicine and are mentioned herein. Radioisotopes of phosphorus can be detected by liquid scintillation counting. There is, however, limited knowledge about remediation as32P and33P are short‐lived.