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

Research output: Contribution to journalArticlepeer-review

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
Pages (from-to)18715-18729
Number of pages15
JournalJournal of the American Chemical Society
Volume142
Issue number43
DOIs
Publication statusPublished - Oct 28 2020

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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