Crystal structure and redox potentials of the tppz-bridged {RuCl(bpy)}⁺ dimer.

ABSTRACT: We report the structural and electrochemical characterization of the binuclear complex [?-(C₂₄H₁₆N₆){RuCl(C₁₀H₈N₂)}₂](PF₆)₂, which contains the bis-tridentate bridging ligand 2,3,5,6-tetra-kis-(pyridin-2-yl)pyrazine (tppz), the monodentate ligand Cl^-, and the bidentate ligand 2,2'-bi-pyridine (bpy) {systematic name: ?-2,3,5,6-tetra-kis-(pyridin-2-yl)pyrazine-bis-[(2,2'-bi-pyridine)-chlorido-ru-thenium(II)] bis-(hexa-fluorido-phosphate)}. The complete [(bpy)(Cl)Ru(tppz)Ru(Cl)(bpy)]²⁺ dication is generated by crystallographic twofold symmetry; the tppz bridging ligand has a significantly twisted conformation, with an average angle of 42.4° between the mean planes of adjacent pyridyl rings. The metal-coordinated chloride ligands are in a trans configuration relative to each other across the {Ru(tppz)Ru} unit. The Ru^II ion exhibits a distorted octa-hedral geometry due to the restricted bite angle [160.6?(3)°] of the tppz ligand. For bpy, the bond lengths of the Ru-N bonds are 2.053?(8) and 2.090?(8)?Å, with the shorter bond being opposite to Ru-Cl. For the tridentate tppz, the Ru-N distances involving the outer N atoms trans to each other are 2.069?(8) and 2.072?(9)?Å, whereas the Ru-N bond involving the central N atom has the much shorter length of 1.939?(7)?Å as a result of the geometric constraints and stronger ?-acceptor ability of the pyrazine-centered bridge. The Ru-Cl distance is 2.407?(3)?Å and the intra-molecular distance between Ru centers is 6.579?(4)?Å. In the crystal, weak C-H?Cl and C-H?F inter-actions consolidate the packing.

SUBMITTER: Rein FN 

PROVIDER: S-EPMC6127700 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature