Synthesis and structural studies of ruthenium(II) 12S4 complexes with 4,4′-bipyridine: The crystal structures of [Ru(12S4)(bpy)Cl](Cl) · H2O and [{Ru(12S4)Cl}2-μ-(bpy)](PF6)2 · 2CH3CN

Reaction of the complex cis-[Ru(12S4)(dmso)Cl]+ (12S4 = 1,4,7,10-tetrathiacyclododecane) and 4,4′-bipyridine (bpy) produces the mononuclear complex [Ru(12S4)(bpy)Cl]+(1) when a 1:1 stoichiometry is employed while a 2:1 stoichiometry (Ru/bpy) produces the bpy bridged binuclear complex, [{Ru(12S4)Cl}2-μ-(bpy)]2+(2). The crystal structures of both complexes show the Ru(II) in a distorted octahedral environment of a cis arrangement formed by the four S donors from the 12S4, a bpy N donor, and a chloride. The 12S4 ligand adopts the same non-C2 symmetric conformation at all metal centers in both structures. The bridging of the 4,4′-bpy ligand to both Ru(II) centers in (2) is indicated by the presence of two resonances in its 1H NMR spectrum and three in its 13C NMR spectrum. The lower symmetry of the mononuclear complex (1) produces more complicated NMR spectra. Cyclic voltammetry for both complexes in CH3CN show a reversible one electron oxidation wave with E1/2 near +670 mV vs. Fc/Fc+ which is assigned as a Ru(II)/Ru(III) couple.

Graphical abstractProgress towards the preparation of a Ru(II)-tetrathioether based molecular square is described with the preparation of the components of one corner and one side and two corners and one side. Two Ru 12S4 moieties are linked by a bridging 4,4′-bipyridine ligand.Figure optionsDownload full-size imageDownload as PowerPoint slide