Bistability of an iron-cobalt binuclear complex

Abstract

Bistability of the four cis/trans isomers of the proposed iron-cobalt binuclear complex [(CO) 2 (benzoate-)Fe II/III (-terephthalate-)Co III/II (-benzoate)(CO) 2 ] 1+ , arising from the Fe II/III ↔ Co III/II intramolecular charge transfer (IMCT) is investigated computationally at (TD)DFT-B3LYP/LanL2DZ level of theory. Energies, geometries, atomic charges, and the UV-Vis spectra are considered in this investigation. Results approve IMCT bistability of all cis/trans isomers by locating two stable states with distinctly different structures and charge distributions (Fe II -Co III and Fe III -Co II oxidation states). Also, well-defined first-order saddle points between these two IMCT states are found and characterized using QST2/QST3 method. Based on the analysis of the calculated charge distributions and the 0.35-1.66 eV activation (barrier) energies of the Fe II -Co III ↔ Fe III -Co II IMCT reactions, it can be predicted that electric field or NIR radiation may be used to switch between the two IMCT states of this bistable binuclear complex. It is also found that the cis/trans isomerization has significant effects on the energetics of this IMCT reaction, and that the trans-Fe II/III -trans-Co III/II isomer is the best candidate for prospective switching application due to having the least energy dissipation and the largest charge transfer. © 2018 Wiley Periodicals, Inc.