Related Experiment Video
Updated: Mar 29, 2026
A Novel Technique for Generating and Observing Chemiluminescence in a Biological Setting
Published on: March 9, 2017
Ligand Field Effects on the Aqueous Ru(III)/Ru(II) Redox Couple from an All-Atom Density Functional Theory
1Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom.
Abstract:
The [RuCl6](4)(-)(aq) → [RuCl6](3)(-)(aq) + e(-) and [Ru(CN)6](4)(-)(aq) → [Ru(CN)6](3)(-)(aq) + e(-) half redox reactions are investigated using density functional based ab initio molecular dynamics methods. The aim is to understand at a microscopic level how the difference in π-bonding of these ligands is reflected in the redox chemistry. To this end, we have computed the redox and reorganization free energies using a method derived from the Marcus theory of electron transfer. The resulting estimate of the free energy change of the full redox reaction between the two coordination complexes is compared to experiment. Our findings indicate that ligand character has an important effect on the vertical ionization chemistry but less on the relaxation of the system after removal or addition of electrons. This enables us to correlate the redox free energies with the HOMO energy levels of the combined solute + solvent system and analyze the redox chemistry in terms of the corresponding energy level diagram.
More Related Videos
Related Concept Videos
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:51Metal-Ligand Bonds
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
01:30Ladder Diagrams: Redox Equilibria
Consider the Fe3+/Fe2+ half-reaction, which has a standard-state potential of +0.771 V. At potentials more positive than +0.771 V, Fe3+ predominates, whereas Fe2+...
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
03:45Formation of Complex Ions