Structure and Properties of Dinuclear [Ru^II([<i>n</i>]aneS₄)] Complexes of 3,6-Bis(2-pyridyl)-1,2,4,5-tetrazine

The synthesis of dinuclear [RuII([n]aneS4)] (where n = 12, 14) complexes of the bridging ligand 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine are reported. The X-ray structures of both of the new complexes are compared to a newly obtained structure for a dinuclear [RuII([9]aneS3)]-based analogue, whose synthesis has previously been reported. A comparison of the electrochemistry of the three complexes reveals that the first oxidation of the [RuII([n]aneS4)]-based systems is a ligand-based couple, indicating that the formation of the radical anion form of the bridging ligand is stabilized by metal center coordination. Spectroelectrochemistry studies on the mixed-valence form of the new complexes suggest that they are Robin and Day Class II systems. The electrochemical and electronic properties of these complexes is rationalized by a consideration of the π-bonding properties of thiacrown ligands.