Multielectron Redox Chemistry of Transition Metal Complexes Supported by a Non‐Innocent N3P2 Ligand: Synthesis, Characterization, and Catalytic Properties

Authors

Denan Wang, Marquette UniversityFollow
Danushka M. Ekanayake, Wayne State UniversityFollow
Sergey V. Lindeman, Marquette UniversityFollow
Cláudio N. Verani, Wayne State University
Adam T. Fiedler, Marquette UniversityFollow

Document Type

Article

Language

eng

Publication Date

10-9-2018

Publisher

Wiley

Source Publication

European Journal of Inorganic Chemistry

Source ISSN

1434-1948

Abstract

A new redox‐active, diarylamido‐based ligand (L^N3P2) capable of κ⁵‐N,N,N,P,P chelation has been used to prepare a series of complexes with the general formula [M^II(L^N3P2)]X, where M = Fe (1; X = OTf), Co (2; X = ClO₄), or Ni (3; X = ClO₄). The diarylamido core of monoanionic L^N3P2 is derived from bis(2‐amino‐4‐methylphenyl)amine, which undergoes condensation with two equivalents of 2‐(diphenylphosphanyl)benzaldehyde to provide chelating arms with both arylphosphine and imine donors. X‐ray structural, magnetic, and spectroscopic studies indicate that the N₃P₂ coordination environment generally promotes low‐spin configurations. Three quasi‐reversible redox couples between +1.0 and –1.5 V (vs. Fc⁺/Fc) were observed in voltammetric studies of each complex, corresponding to M^II/M^III oxidation, L^N3P2‐based oxidation, and M^II/M^I reduction (in order of highest to lowest potential). Spectroscopic and computational analyses of 3^ox – generated via chemical one‐electron oxidation of 3 – revealed that a stable diarylaminyl radical (L^N3P2·) is formed upon oxidation. The ability of the Co^II complex (2) to function as an electrocatalyst for H₂ generation was evaluated in the presence of weak acids. Moderate activity was observed using 4‐tert‐butylphenol as the proton source at potentials below –2.0 V. The insights gained here will assist in the future design of pentadentate mixed N/P‐based chelates for catalytic processes.

Comments

Accepted version. European Journal of Inorganic Chemistry, Vol. 2018, No. 37 (October 9, 2018): 4133-4141. DOI. © 2018 John Wiley & Sons, Inc. Used with permission.

Recommended Citation

Wang, Denan; Ekanayake, Danushka M.; Lindeman, Sergey V.; Verani, Cláudio N.; and Fiedler, Adam T., "Multielectron Redox Chemistry of Transition Metal Complexes Supported by a Non‐Innocent N3P2 Ligand: Synthesis, Characterization, and Catalytic Properties" (2018). Chemistry Faculty Research and Publications. 960.
https://epublications.marquette.edu/chem_fac/960