Pyrazine-Coordinated Dinuclear and Mononuclear Ruthenium Complexes Formed via the Conversion of the Triply Chlorido-Bridged Diruthenium(II) Complex.

The pyrazine-coordinated dinuclear and mononuclear ruthenium complexes were synthesized through the framework conversion reactions of the triply chlorido-bridged diruthenium(II) complex [{Ru II,II (bbpma)} 2 (μ-Cl) 3 ] + (bbpma; benzylbis(2-pyridylmethyl)amine, [ 1 ] + ) in the presence of pyrazine, which could function as the simple molecular multinucleation ligand of metal compounds. A reduction reaction of fac -[Ru III Cl 3 (bbpma)] with zinc in the presence of hydrochloric acid afforded [ 1 ] + in solution, and the following addition of pyrazine (1 equiv) in the solution led to the formation of a singly pyrazine (pz)-bridged diruthenium complex, [{Ru II,II (μ-Cl 2 ZnCl 2 )(bbpma)} 2 (μ-pz)] ([ 2(II,II)(ZnCl 2 ) 2 ]). The stoichiometric two-electron oxidation of [ 2(II,II)(ZnCl 2 ) 2 ] was successfully proceeded, and a Ru(III)-Ru(III) species, [{Ru III,III Cl 2 (bbpma)} 2 (μ-pz)](PF 6 ) 2 ([ III , III ](PF 6 ) 2 ), was isolated. The reaction of [ 1 ] + with excess amounts of pyrazine without hydrochloric acid afforded mononuclear Ru(III) and Ru(II) complexes containing one or two pyrazine, fac -[RuCl m (pz) 3- m (bbpma)] + ( m = 2; [ 3 ] + ; m = 1; [ 4 ] + ). The details of the electrochemical and spectroscopic properties of [ 1 ] + -[ 4 ] + in organic and aqueous solutions were discussed.