Use of silver(I) complexes in synthesis of bis- and tris-[2-(arylazo)pyridine] complexes of ruthenium(II) and investigation of solid-state isomerisation

Abstract

Efficient, new and direct synthetic routes to isomeric [RuCl₂L₂] and [RuL₃][ClO₄]₂·H₂O [L = 2-(arylazo)pyridine] complexes, based on the reaction of hydrated RuCl₃ and [AgL₂]ClO₄, have been elaborated. The identity of the compounds were established from elemental analyses and spectral data. The advantages of the new methods are highlighted. Solid-state isomerisation of the dichloride complexes has been studied by different thermal methods. It is shown that two (trans,trans and cis,cis) out of the three isomers of [RuCl₂L₂] are converted into the third (trans,cis) isomer on heating. Analyses of differential scanning calorimetry data reveal that the thermal isomerisation reactions proceed through similar intermediates. The relative thermal stabilities of the different isomers of [RuCl₂L₂] are also briefly noted.