Nitratoaquo complexes of nitrosylruthenium III

Abstract

The five complexes with nitrato or aquo groups adjacent to nitrosyl in octahedrally bonded RuNO III have been identified by cation exchange, paper chromatography, and extraction by tertiary amines. The assignment of the cis and trans dinitrato complexes is based on the difference in their rates of formation from the mononitrato complex being governed by a trans nitrato effect. The cis is the more stable form, the ratio [ cis]/[ trans] at 20° being ca. 1·4; it is also the less extractable by organic solvents. In contrast to the behaviour shown by other pairs of geometric isomers with hexa coordination, the cis isomer is eluted before the trans isomer from a mixture of the two adsorbed on a cation exchange resin. The mole fractions of the mononuclear complexes at equilibrium in 1–12 M HNO 3 have been measured and the rate constants between them determined. The infra-red spectra of the tri- and tetranitrato complexes are given.