Spin crossover-coupled electron transfer of [M(tacn)(2)](3+/2+) complexes (tacn = 1,4,7-triazacyclononane; M = Cr, Mn, Fe, Co, Ni).
The role of spin state equilibria on the thermodynamics of electron transfer in [M(tacn)(2)](3+/2+) complexes (tacn = 1,4,7-triazacyclononane; M = Cr, Mn, Fe, Co, Ni) was examined using density functional theory at the B3LYP*/cc-pVTZ(-f) level coupled to a continuum solvation model to afford excellent agreement between computed and experimental redox properties. An intuitive explanation of the previously observed nonperiodic trend in reduction potentials, which display a sawtooth pattern along the first-row transition metal series, is offered utilizing a novel diagrammatic illustration of the relationship between spin state energetics and reduction potentials. This representation leads to a generalized proposal for analyzing and designing nearly isoenergetic spin states of transition metals in a given ligand environment. A new ligand specific parameter alpha that allows for quantifying the differential reduction potential as a function of the metal identity is introduced, and a novel protocol is presented that divides the ligand-metal interactions into primary and secondary characteristics, which we anticipate will be useful for rationally designing the electronics of transition metal complexes in general.
Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, USA.
Richard L
RL
Lord
Franklin A
FA
Schultz
Mu-Hyun
MH
Baik
D003198:Computer Simulation; D004583:Electrons; D006571:Heterocyclic Compounds / Q000737:chemistry*; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013816:Thermodynamics; D028561:Transition Elements / Q000737:chemistry*
D006571:Heterocyclic Compounds; D008024:Ligands; D009942:Organometallic Compounds; D028561:Transition Elements; C075712:1,4,7-triazacyclononane