Silver(III) biguanides

Abstract

A series of quadricovalent cationic complexes of silver(III) with biguanide and with methylbiguanide having the composition [Ag^IIIL₂]X₃, where L is a bidentate ligand and X a univalent anion, has been prepared and characterised. In alkaline, neutral, and feebly acidic medium (pH > 5), the biguanide molecule possesses filled π-type delocalised orbitals. Some of the d electrons in the hypothetical Ag^I complex are forced to occupy higher-energy antibonding orbitals from which they can be removed by oxidation to give an Ag^III complex. All the compounds were found to be diamagnetic, indicating dsp² hybridisation.