Redox-Associated η<sup>1</sup> to η<sup>2</sup> Conversion of Disulfide Ligands in Dinuclear Ruthenium Complexes

Disulfide-bridged dinuclear ruthenium complexes [{Ru(MeCN)(P(OMe)<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(μ-X)(μ,η<sup>2</sup>-S<sub>2</sub>)][ZnX<sub>3</sub>(MeCN)] (X = Cl (<b>2</b>), Br (<b>4</b>)), [{Ru(MeCN)(P(OMe)<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(μ-Cl)<sub>2</sub>(μ,η<sup>1</sup>-S<sub>2</sub>)](CF<sub>3</sub>SO<sub>3</sub>) (<b>5</b>), [{Ru(MeCN)(P(OMe)<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(μ-Cl)(μ,η<sup>2</sup>-S<sub>2</sub>)](BF<sub>4</sub>) (<b>6</b>), and [{Ru(MeCN)<sub>2</sub>(P(OMe)<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(μ-Cl)(μ,η<sup>1</sup>-S<sub>2</sub>)](CF<sub>3</sub>SO<sub>3</sub>)<sub>3</sub> (<b>7</b>) were synthesized, and the crystal structures of <b>2</b> and <b>4</b> were determined. Crystal data:  <b>2</b>, triclinic, <i>P</i>1̄, <i>a</i> = 15.921(4) Å, <i>b</i> = 17.484(4) Å, <i>c</i> = 8.774(2) Å, α = 103.14(2)°, β = 102.30(2)°, γ = 109.68(2)°, <i>V</i> = 2124(1) Å<sup>3</sup>, <i>Z</i> = 2, <i>R </i>(<i>R</i><sub>w</sub>) = 0.055 (0.074); <b>4</b>, triclinic, <i>P</i>1̄, <i>a</i> = 15.943(4) Å, <i>b</i> = 17.703(4) Å, <i>c</i> = 8.883(1) Å, α = 102.96(2)°, β = 102.02(2)°, γ = 109.10(2)°, <i>V</i> = 2198.4(9) Å<sup>3</sup>, <i>Z</i> = 2, <i>R</i> (<i>R</i><sub>w</sub>) = 0.048 (0.067). Complexes <b>2</b> and <b>4</b> were obtained by reduction of the disulfide-bridged ruthenium complexes [{RuX(P(OMe)<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(μ-X)<sub>2</sub>(μ,η<sup>1</sup>-S<sub>2</sub>)] (X = Cl (<b>1</b>), Br (<b>3</b>)) with zinc, respectively. Complex <b>5</b> was synthesized by oxidation of <b>2</b> with AgCF<sub>3</sub>SO<sub>3</sub>. Through these redox steps, the coordination mode of the disulfide ligand was converted from μ,η<sup>1</sup> in <b>1</b> and <b>3</b> to μ,η<sup>2</sup> in <b>2</b> and <b>4</b> and further reverted to μ,η<sup>1</sup> in <b>5</b>. Electrochemical studies of <b>6</b> indicated that similar conversion of the coordination mode occurs also in electrochemical redox reactions.