The synthesis and characterization of Ru(II) and Ru(II)-Ag(I) compounds are described, in view of their potential use in on/off switchable metal-ridge-metal nanodevices. The compound trans-Ru(bipy)(4)Cl-2 (1) [bipy, 4,4'-bipyridine] has been prepared by Ru(DMSO)(4)Cl-2 (2) (DMSO, dimethylsufoxide) and an excess of bipy. The compound has been fully characterised by physico-chemical, spectroscopic and single crystal X-ray determinations. trans-Ru(bipy)(4)Cl-2 has been employed as building block in a self-assembly reaction with AgNO3 obtaining the inorganic polymer {[Ru(bipy)(4)Cl2Ag]NO3 (CHCl3)center dot 6H(2)O}(n) (3). The self-assembled Ru-Ag compound has been investigated by infrared (IR), ultraviolet (UV) and visible (vis) spectroscopy, elemental analyses, inductively coupled plasma optical emission spectroscopy (ICP-OES) and thermogravimetric analysis coupled with infrared detector (TGA-IR). The electrochemical behaviour of 1 and 3 have been studied by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). 1 and 3 have been tested both as soluble species in non-aqueous solvents and as self-assembled molecules on gold electrodes in aqueous medium. The electrochemical behaviour of the parent compounds trans-Ru(pyz)(4)Cl-2 (4) [pyz, pyrazine] and {[Ru(pyz)(4)Cl2Ag]NO3}(n) (5) have been also investigated for comparison. (c) 2006 Elsevier Ltd. All rights reserved.