Complexation of a tetradentate tetra-anionic ligand to osmium(IV): a step towards the development of multianionic chelating ligands for use in stabilizing oxidizing inorganic complexes

Abstract

The compound 1,2-bis(3,5-dichloro-2-hydroxybenzamido)ethane [H₄(chba-Et)](1) radily co-ordinates to osmium(VI) as a tetradentate tetra-anion; the X-ray crystal structure of the reduced complex, K₂[{Os(η⁴-chba–Et)(OPPh₃)}₂–O](3), demonstrates that this ligand can bind as a tetradentate tetra-anion to the equatorial sites of a single octahedral metal centre and the potassium ion is found in two unusual co-ordination environments in complex (3).