Utilizing Diruthenium Components for the Design of Cyanide-Linked Tri- and Tetranuclear Organometallic Complexes with Multistep One-Electron Redox Processes

Anilinopyridinate-supported Ru2x+ (x = 5 or 6) paddlewheel complexes with labile axial ligands

Five new metal–metal bonded Ru₂ amidinate compounds with labile axial ligands are presented and discussed.

Discrete and Monodimensional Heteropolynuclear Structures Formed by Tetracarboxylatodiruthenium(II,III) and Perrhenato Fragments

Reaction between cationic units of carboxylate-bridged diruthenium complexes [Ru(2)(mu-O(2)CR)(4)](+) (R = Me, CMePh(2), CMe(3), CH(2)CH(2)OMe, C(Me)=CHEt, C(6)H(4)-p-OMe, Ph) and tetrabutylammonium perrhenate gives complexes with different arrangements in the solid state. Thus, the compounds Ru(2)(mu-O(2)CR)(4)(ReO(4)) [R = Me (1), CMePh(2) (2), CMe(3) (3), CH(2)CH(2)OMe (4), C(Me)=CHEt (5), C(6)H(4)-p-OMe (6), Ph (7)] have polymeric structures with the diruthenium units linked by perrhenate ligands in the axial positions. The structures of complexes 3.THF and 4 were established by single-crystal X-ray diffraction. The tetrahedral geometry of the ReO(4)(-) anion permits the formation of a chain close to the linearity. In contrast to the polymeric chains observed in complexes 1-7, the reaction of [Ru(2)(mu-O(2)CPh)(4)](+) with NBu(4)ReO(4) also affords the compounds Ru(2)(mu-O(2)CPh)(4)(ReO(4))(H(2)O) (8) and NBu(4)[Ru(2)(mu-O(2)CPh)(4)(ReO(4))(2)] (9) depending on the reaction conditions. The structure of 8 consists of cationic and anionic units, [Ru(2)(mu-O(2)CPh)(4)(H(2)O)(2)](+) and [Ru(2)(mu-O(2)CPh)(4)(ReO(4))(2)](-), linked by hydrogen bonds, which give a three-dimensional net. The structure of complex 9.0.5H(2)O has an anionic unit similar to that of 8, whose counterion is NBu(4)(+). The Ru-Ru bond distances are slightly longer in [Ru(2)(mu-O(2)CPh)(4)(ReO(4))(2)](-) than in the polymeric compounds Ru(2)(mu-O(2)CR)(4)(ReO(4)). The magnetic behavior owes to the existence of zero-field splitting (ZFS) and a weak antiferromagnetic coupling. The experimental data are fitted with a model that considers the ZFS effect using the Hamiltonian (D) = SDS. The weak antiferromagnetic coupling is introduced as a perturbation, using the molecular field approximation.

Cyanide Adducts on the Diruthenium Core of [Ru2(L)4]+ (L = ap, CH3ap, Fap, or F3ap). Electronic Properties and Binding Modes of the Bridging Ligand

The products of the reaction between CN(-) and four different diruthenium complexes of the type Ru(2)(L)(4)Cl where L = 2-CH(3)ap (2-(2-methylanilino)pyridinate anion), ap (2-anilinopyridinate anion), 2-Fap (2-(2-fluoroanilino)pyridinate anion), or 2,4,6-F(3)ap (2-(2,4,6-trifluoroanilino)pyridinate anion) are reported. Mono- and/or dicyano adducts of the type Ru(2)(L)(4)(CN) and Ru(2)(L)(4)(CN)(2) are found exclusively as reaction products when either the 2-CH(3)ap or the ap derivative is reacted with CN(-), but diruthenium complexes with formulations of the type Ru(2)(F(x)ap)(3)[mu-(o-NC)F(x-1)ap](mu-CN) or Ru(2)(F(x)ap)(4)(mu-CN)(2) (x = 1 or 3) are also generated when Ru(2)(Fap)(4)Cl or Ru(2)(F(3)ap)(4)Cl is reacted with CN(-). More specifically, four products formulated as Ru(2)(Fap)(4)(CN), Ru(2)(Fap)(4)(CN)(2), Ru(2)(Fap)(3)[mu-(o-NC)ap](mu-CN), and Ru(2)(Fap)(4)(mu-CN)(2) can be isolated from a reaction of CN(-) with the Fap derivative, but the exact type and yield of these compounds depend on the temperature at which the experiment is carried out. In the case of the F(3)ap derivative, the only diruthenium complex isolated from the reaction mixture has the formulation Ru(2)(F(3)ap)(3)[mu-(o-NC)F(2)ap](mu-CN) and this compound has structural, electrochemical, and spectroscopic properties quite similar to that of previously characterized Ru(2)(F(5)ap)[mu-(o-NC)F(4)ap](mu-CN). Both the mono- and dicyano derivatives synthesized in this study possess the isomer type of their parent chloro complexes. The Ru-Ru bond lengths of Ru(2)(ap)(4)(CN) and Ru(2)(2-CH(3)ap)(4)(CN) are longer than those of Ru(2)(ap)(4)Cl and Ru(2)(CH(3)ap)(4)Cl, respectively, and this is accounted for by the strong sigma-donor properties of the CN(-) ligand as compared to Cl(-). The Ru-C bonds in Ru(2)(ap)(4)(CN)(2) are significantly shorter than those in Ru(2)(ap)(4)(CN), thus revealing a greatly enhanced Ru-CN interaction in the dicyano adduct, a result which is also indicated by the fact that nu(CN) in Ru(2)(ap)(4)(CN)(2) is 50 cm(-1) higher than nu(CN) in Ru(2)(ap)(4)(CN). Although both (4,0) Ru(2)(ap)(4)(CN)(2) and (3,1) Ru(2)(Fap)(4)(CN)(2) possess the same formulation, there are clear structural differences between the two complexes and this can be explained by the fact that the two cyano derivatives possess a different binding symmetry of the bridging ligands. Each mono- and dicyano adduct was electrochemically investigated in CH(2)Cl(2) containing TBAP as supporting electrolyte. Ru(2)(ap)(4)(CN), Ru(2)(CH(3)ap)(4)(CN), and Ru(2)(Fap)(4)(CN) undergo one reduction and two oxidations. The two dicyano adducts of the ap and Fap derivatives are characterized by two reductions and one oxidation. The potentials of these processes are all negatively shifted in potential by 400-720 mV with respect to half-wave potentials for the same redox couples of the monocyano derivatives, with the exact value depending upon the specific redox reaction.