Chloro and Azido Diruthenium Complexes Bearing Electron-Rich N,N′,N′′-Triphenylguanidinate Ligands

Abstract

The reaction of Ru(2)(OAc)(4)Cl with N,N',N''-triphenylguanidine (HTPG) produces one of two different compounds depending on the reaction conditions. In acetone in the presence of triethyl amine, the reaction produces tri-substituted Ru(2)(TPG)(3)(OAc)Cl, and in refluxing xylene, the tetra-substituted Ru(2)(TPG)(4)Cl is produced. Both of these new complexes can be cleanly converted into their corresponding azido analogues by reaction with sodium azide in methanol. The X-ray crystal structures of Ru(2)(TPG)(3)(OAc)Cl, Ru(2)(TPG)(3)(OAc)N(3), and Ru(2)(TPG)(4)Cl are presented, along with magnetic, electrochemical, and spectral measurements for each compound. Studies in solution show that, in contrast to Ru(2)(TPG)(3)(OAc)Cl, Ru(2)(TPG)(4)Cl is sterically hindered at the axial positions, and readily dissociates a chloride ion at high ionic strength. Equilibrium constants for chloride association and dissociation have been estimated. Mass spectrometric data suggest that the two azido complexes are precursors to new diruthenium nitrido species.

Electronic Structure of Anilinopyridinate-Supported Ru25+ Paddlewheel Compounds

“…To date, the D values of relatively few Ru 2 5+ complexes supported by N , N -donor equatorial ligands have been determined, − in contrast to the many examples of Ru 2 5+ carboxylate compounds that have been examined . The | D | values determined here fall within the range of those for reported compounds (∼50–80 cm –1 ). − Though the sign of D cannot be determined by the methods employed here, we presume these are positive on the basis of the EPR results of all Ru 2 5+ complexes supported by equatorial N,N -donors that have been measured to date. ,,− The (isotropic) g value of 2.03 for 2 determined here compares reasonably well with the frozen solution-state EPR results of g ⊥ = 2.01 and g || = 1.89 ( g iso = 1.97) …”

A Synthetic Oxygen Atom Transfer Photocycle from a Diruthenium Oxyanion Complex

“…However, the fact that the redox potentials change when the electrolyte is changed to NBu 4 NO 3 or NBu 4 ClO 4 indicates that both 4 and 5 undergo the following equilibrium in solution: Ru 2 (chp) 4 X ⇌ [Ru 2 (chp) 4 ] + + X – . Other diruthenium compounds show similar behavior . Addition of excess X – shifts this equilibrium to the left.…”

A Diruthenium Catalyst for Selective, Intramolecular Allylic C–H Amination: Reaction Development and Mechanistic Insight Gained through Experiment and Theory

“…Despite a rich history of investigation, these complexes have seldom found use in catalytic reaction development (examples include sulfide oxygenation and amine and alcohol oxidation) . Germane to our interests, recent reports by Berry describe the preparation and characterization of a unique diruthenium nitride complex capable of stoichiometric aryl C–H amination of a ligand residue . For our purposes, one evident advantage of these mixed-valent ruthenium dimers for catalytic atom-transfer processes is the high one-electron oxidation potentials for both tetracarboxylate and tetraamidate complexes .…”