title: Synthesis, structures, magnetism and electrochemical properties of triruthenium-acetylide complexes.
abstract: A series of triruthenium complexes with arylacetylide axial ligands Ru(3)(dpa)(4)(C(2)X)(2)(BF(4))(y)(dpa = dipyridylamido; X = Fc, y= 0 (1); X = Ph, y= 0 (2); X = PhOCH(3), y= 1 (3); X = PhC(5)H(11), y= 1 (4); X = PhCN, y= 0 (5); X = PhNO(2), y= 0 (6)) have been synthesized. The crystal structures show that the Ru-Ru bond lengths (2.3304(9)-2.3572(5)A) of these compounds are longer than those of Ru(3)(dpa)(4)Cl(2)(Ru-Ru=2.2537(1)A). This is ascribed to the formation of the stronger pi-backbonding from metal to axial ligand which weakens the Ru-Ru interactions and the bond order is reduced in the triruthenium unit. Cyclic voltammetry and differential pulse voltammetry show that compound exhibits electronic coupling between the two ferrocenyl units with DeltaE(1/2) close to 100 mV. Compounds 2-6 display three triruthenium-based reversible one-electron redox couples, two oxidations and one reduction, and the electrode potentials shift upon varying the substituents. A linear relationship is observed when the Hammett constants are plotted against the redox potentials.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Ching-Kuo
authors.initials: CK
authors.lastname: Kuo
authors.forename: Jung-Che
authors.initials: JC
authors.lastname: Chang
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Yeh
authors.forename: Gene-Hsiang
authors.initials: GH
authors.lastname: Lee
authors.forename: Chih-Chieh
authors.initials: CC
authors.lastname: Wang
authors.forename: Shie-Ming
authors.initials: SM
authors.lastname: Peng