Bis-ferrocenyl-pyridinediimine trinuclear mixed-valent complexes with metal-binding dependent electronic coupling: Synthesis, structures, and redox-spectroscopic characterization

Cole Carter, Yosi Kratish, Titel Jurca, Yanshan Gao*, Tobin J. Marks

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

A family of metal dichloride complexes having a bisferrocenyl- substituted pyridinediimine ligand was systematically synthesized ((Fc2PDI)MCl2, M = Mg, Zn, Fe, and Co) and characterized crystallographically, spectroscopically, electrochemically, and computationally. Electronic coupling between the ligand ferrocene units is switched on upon binding to a MCl2 fragment, as evidenced by both sequential oxidation of the ferrocenes in cyclic voltammetry (ΔEox ≈ 200 mV) and by Inter-Valence Charge Transfer electronic excitations in the near IR. Additionally, UV-vis spectra are used to directly observe orbital mixing between the ferrocenyl units and the imine π system since breaking of the orbital symmetry results in allowed transitions (ϵ = 2800 M-1cm-1 vs ϵ ≈ 200 M-1cm-1 in free ferrocene) as well as broadening and red-shifting of the ferrocenyl transitions-indicating organic character in formerly pure metal-centered transitions. DFT analysis reveals that interaction between the ferrocenes and the MCl2 fragment is small and suggests that communication is mediated by better energy matching between the ferrocene and organic π∗ orbitals upon coordination, allowing superexchange coupling through the LUMO. Furthermore, single crystal diffraction data obtained from oxidation of one and both ferrocenes show distortions, introducing the empty dxy/dx2-y2 orbitals into the secondary coordination sphere of the MCl2 fragment. Such structural rearrangements are infrequent in ferrocenyl mixedvalent compounds, and implications for catalysis as well as electronic communication are discussed.

Original languageEnglish (US)
Pages (from-to)18715-18729
Number of pages15
JournalJournal of the American Chemical Society
Volume142
Issue number43
DOIs
StatePublished - Oct 28 2020

Funding

Financial support was provided by the National Science Foundation through Grant No. CHE-1856619 (C.C.). This work used the IMSERC facility at Northwestern University, which has received support from the NSF (CHE-1048773 and CHE-9871268); Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI-1542205); the State of Illinois and International Institute for Nanotechnology. We also thank Katia Kratish for graphic design of the Table of Contents figure, as well as Prof. Y. Apeloig of the Technion Israel Institute of Technology for providing computational resources. We also thank Dr. Boris Tumanskii of the Technion Israel Institute of Technology for informative and helpful discussions. Dr. N. LaPorte of Northwestern U. assisted with spectroelectrochemical and NIR experiments.

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry

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