Spectroscopic evidence for Metal-Metal electronic coupling of suspected L5RumCNFen(CN)5 System

Abstract

Inorganic donor-acceptor complexes containing inter-valence (IT) or metal-to-metal charge transfer bands have received significant attention in the last few decades due to their potential applications to solar energy conversions, photocatalysis and/or electrochromic materials. For this purpose, L5RulllCNFel,(CN) 5 complex (where L = H20, Cl), similar to Prussian blue, has been synthesized. By mixing aqueous solutions of brown-coloured RuCB and light yellow K4 [Fe(CN)6], the colour of the resultant solution suddenly changed to dark green. The electronic spectrum of the solution mixture showed an intense inter-valence (IT) charge transfer absorption with an extinction of 362 M^cm' 1 at approximately 742 nm. The absorption spectrum is totally different from that of the relevant monomers. Dark green solids were isolated after leaving the solution for few hours at room temperature. The solid is very insoluble in many common solvents. The estimated Ru/Fe ratio of the new polymetallic system, using the Job’s method, was found to belli.