The 1,6,7,12-Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme-Electrode Process.

The homodinuclear ruthenium(II) complex [{Ru(l-N Me )} (μ-tape)](PF ) {[1](PF ) } (l-N Me =N,N'-dimethyl-2,11-diaza[3.3](2,6)-pyridinophane, tape=1,6,7,12-tetraazaperylene) can store one or two electrons in the energetically low-lying π* orbital of the bridging ligand tape. The corresponding singly and doubly reduced complexes [{Ru(l-N Me )} (μ-tape )](PF ) {[2](PF ) } and [{Ru(l-N Me )} (μ-tape )](PF ) {[3](PF ) }, respectively, were electrochemically generated, successfully isolated and fully characterized by single-crystal X-ray crystallography, spectroscopic methods and magnetic susceptibility measurements. The singly reduced complex [2](PF ) contains the π-radical tape and the doubly reduced [3](PF ) the diamagnetic dianion tape as bridging ligand, respectively. Nucleophilic aromatic substitution at the bridging tape in [1] by two sulfite units gave the complex [{Ru(l-N Me )} {μ-tape-(SO ) }] ([4] ). Complex dication [4] was exploited as a redox mediator between an anaerobic homogenous reaction solution of an enzyme system (sulfite/sulfite oxidase) and the electrode via participation of the low-energy π*-orbital of the disulfonato-substituted bridging ligand tape-(SO ) (E =-0.1 V versus Ag/AgCl/1 m KCl in water).