Nitric oxide dimerization in gas phase and aromatic hosts (benzene) has been investigated with ab initio quantum mechanics. Using the (RO)MP2-aug-cc-pVDZ method, the computed bond dissociation energy (ON...NO) and geometry of (NO)2 in the gas phase are consistent with the reported spectroscopic data. A relatively strong interaction (-5.4 kcal/mol) between (NO)2 and benzene indicates that aromatic surrounding enhances the NO dimerization. Calculations on reactions of phosphine and methanethiol with NO and (NO)2 show that the dimer is much more reactive. This explains reactions of NO with phosphines and thiols.

Was macht eine gute Höhle aus? Ein molekularer Hohlraum ermöglichte die Stabilisierung eines Selenenyliodid(RSeI)‐Intermediats, das bei der Abspaltung des 5′‐Iodsubstituenten eines Thyroxinderivats mit einem Organoselenol entsteht (siehe Schema). Die für den Iodthyronin‐Deiodinase‐Katalysezyklus vorgeschlagenen chemischen Prozesse wurden experimentell bestätigt.

[structure: see text]. A stable selenenic acid was synthesized by direct oxidation of a selenol bearing a novel bowl-type substituent with H2O2, and its structure was established by X-ray crystallographic analysis. Selenenyl sulfides obtained by the reaction of the selenenic acid with 1,4-dithiols were reduced to the corresponding selenol by treatment with a tertiary amine, thus achieving the experimental demonstration of three processes included in the catalytic cycle of glutathione peroxidase.