Relationships between structure and redox properties of dodecacarbonyl(.mu.4-.eta.2-diphenylacetylene)tetraruthenium and [Et4N]2[Ru4(CO)11(.mu.4-.eta.2-C2Ph2)

Abstract

The cyclic voltammograms of Ru 4 (CO) 12 (C 2 Ph 2 ) (1) contain three irreversible peaks. The initial two-electron reduction of 1 is followed by loss of a CO ligand, and the product was identified spectroscopically in a bulk electrochemical experiment. This product, [Et 4 N] 2 [Ru 4 (CO) 11 (C 2 Ph 2 )] (3), was also prepared independently by chemical reduction of 1 with Na/Hg. The electrochemistry of 3 was elucidated by variable scan rate experiments and digital simulation. A single-crystal X-ray structure determination reveals a dinegative anion containing a butterfly Ru 4 core, a μ 4 -η 2 -C 2 Ph 2 and two bridging and nine terminal CO ligands. Crystal data: monoclinic