Predominantly NO-centered reduction was observed by EPR and IR spectroelectrochemistry to occur reversibly at low temperatures for [Cl(5)Ir(NO)](-). In contrast, the [Cl(5)Ru(NO)](2-) ion was found to undergo only irreversible reduction but reversible oxidation to a ruthenium(III) species at -40 degrees C. DFT calculations were used to establish the electronic structures and to rationalise the different stabilities. The calculations also reveal orientation-dependent energies and EPR properties between staggered and eclipsed conformations.

Coordinated C-nitrosochloroalkanes were obtained by electrophilic addition of K[IrCl5NO] to cyclooctene or dicyclopentadiene; in the last case, the crystal structure of trans-[IrCl4(CH3CN)(syn-1-chloro-2-nitroso-1,2-dihydrodicyclopentadiene)] was determined by X-ray diffraction. Although the reaction between NOCl and alkenes is well-known, there are very few examples of clean electrophilic addition of coordinated NO+ to alkenes.

In the present work we describe the formation of primary aromatic and aliphatic coordinated nitrosamines by reaction of the extremely reactive K[IrCl 5 -NO] with p-toluidine and 2,2,2-trifluoroethylamine, respectively. After the counteranion of the product was changed to tetraphenylphosphonium, crystal structures could be determined by X-ray diffraction. Complexes containing the highly unstable primary nitrosamines as ligands are generally scarce; moreover, to our knowledge this is the first example of isolated primary nitrosamines coordinated to a metal center through the NO moiety.