Elaine S. Dodsworth

Trends in metal–ligand orbital mixing in generic series of ruthenium N-donor ligand complexes—effect on electronic spectra and redox properties

Abstract Generic series of complexes [Ru(bpy) 3− n (LL) n ] 2+ (bpy=2,2′-bipyridine), where LL is a diimine ligand including specifically 2,2′-bipyrazine (bpz), 2,2′-azobipyridine (abpy), and o -benzoquinonediimine (bqdi), are studied with respect to their electrochemistry, optical spectroscopy and electronic structure as elucidated using Zerners INDO/S method. Characteristics of their electrochemistry and optical spectroscopy are explained in terms of mixing between ruthenium d orbitals and diimine ligand π and π* orbitals, increasing in importance from bpy to bpz to abpy to bqdi. In this last case, these species have characteristics not unlike fully delocalized organic molecules.

Correlations between Electrochemical Potentials and Optical Charge Transfer Energies in Ruthenium Bipyridine Derivatives.

Abstract Linear relationships are discussed linking the Ru → π * (bpy) charge transfer transition energy in the species [Ru(bipyridine) 2 XY] n + (X, Y various non-diimine ligands, n = 0, 1, 2) and the observed potentials E [Ru(III/Ru(II)], E [(bpy)/(bpy − )] and their difference. The conditions under which such relationships might be valid are investigated. Correlation of E [Ru(III)/Ru(II)] with E [(bpy)/(bpy − )] is also explored. The results permit the use of optical energies to calculate CT energies and vice versa.

Bis(dioxolene)(bipyridine)ruthenium redox series

Preparation des complexes [Ru(bpy)(dioxolene) 2 ] u+ par electrolyse a potentiel controle des especes meres. Donnees IR, Raman, RMN, RPE

Relationships between Electronic Spectroscopy and Electrochemistry. A Probe of Reorganisation Energies.

Abstract The electronic spectra and electrochemical potentials of the species [Ru(bipy) x (NN) 3- x ] 2+ (bipy = 2,2′-bipyridine. NN = unsaturated diimine, x = 1,2) are correlated via fundamental relationships involving reorganisation and solvation energies. It is argued that the presence of two distinct Ru → ligand charge transfer transitions allows comparison of the reorganisation energies therefore.

Correlation of electronic charge transfer transitions and electrochemical potentials.: The bipyrazine(tetpacarbonyl) molybdenum(0) system in various solvents

Abstract Using a free-energy diagram, a relationship is drawn between an optical charge transfer energy and the electrochemical potentials of the donor and acceptor orbitals concerned. The charge transfer spectroscopy and electrochemical potentials of the title complex were studied in various solvents. A linear correlation, with negative slope, was observed between the difference in oxidation and reduction potentials and an MLCT transition. Using some additional solvent data, a number of useful parameters were derived in a fashion which would not be possible through consideration of either technique alone.

Proton-Induced Disproportionation of a Ruthenium Noninnocent Ligand Complex Yielding a Strong Oxidant and a Strong Reductant

The complex Ru(II)(NH(3))(2)(o-benzoquinonediimine)Cl(2) undergoes a reversible apparent acid/base reaction, although it has no obvious basic lone pairs. The reaction is a proton-assisted disproportionation yielding an oxidant ([Ru(III)(NH(3))(2)(o-benzoquinonediimine)Cl(2)](+)) and a reductant ([Ru(III)(NH(3))(2)(o-phenylenediamine)Cl(2)](+)). These species were characterized by electrochemistry, ultraviolet-visible light (UV-vis), vibrational (infrared (IR) and Raman), mass and electron paramagnetic resonance (EPR) spectroscopy, and X-ray structural analysis. The reaction is shown to be downhill from an isodesmic calculation. Three different isosbestic interconversions of the parent and product species are demonstrated. The electronic structures of these species were analyzed, and their optical spectra assigned, using density functional theory (DFT) and time-dependent DFT. This disproportionation of a noninnocent ligand complex may be relevant to the application of noninnocent ligands in organometallic catalysis and in the biological milieu.

Mono- and di-nuclear complexes of molybdenum carbonyl derivatives with pyridine-2-carbaldehyde azine and phosphines: syntheses, structure, spectroscopic and electrochemical characterisation and solvatochromic effects

Complexes containing phosphorus-donor ligands, [Mo(CO)3(PPh3)(pa)](pa = pyridine-2-carbaldehyde azine), [Mo2(CO)6(PPh3)2(µ-pa)], [Mo2(CO)7(PPh3)(µ-pa)] and [Mo2(CO)6(µ-dppe)(µ-pa)][dppe = 1,2-bis(diphenylphosphino)ethane], have been characterised by infrared and electronic spectroscopy, cyclic voltammetry and for the [Mo2(CO)6(µ-dppe)(µ-pa)] complex a single crystal X-ray structure. All of the complexes show strong solvatochromism which has been analysed both by using the empirical parameter E*MLCT and by using McRaes equation. The results are compared with those of their parent complexes [Mo(CO)4(pa)] and [Mo2(CO)8(µ-pa)], and with the results of extended-Huckel calculations with charge iteration.