Electronic Finetuning of a Bio-inspired Iron(II) tetra-NHC Complex by trans Axial Isocyanide Substitution

Jonas F. Schlagintweit; Carolin Hintermeier; Markus R. Anneser; Eva Maria H.J. Esslinger; Stefan Haslinger; Fritz E. Kühn

doi:10.1002/asia.202000214

Electronic Finetuning of a Bio-inspired Iron(II) tetra-NHC Complex by trans Axial Isocyanide Substitution

Jonas F. Schlagintweit
, Carolin Hintermeier
, Markus R. Anneser
, Eva Maria H.J. Esslinger
, Stefan Haslinger
, Fritz E. Kühn

Associate Professorship of Molecular Catalysis

Technical University of Munich

Research output: Contribution to journal › Article › peer-review

12 Scopus citations

Abstract

The synthesis of trans axially substituted mono- (1 a) and bis(tert-butylisocyanide) (1 b) derivatives of the highly active homogeneous bio-inspired iron(II) olefin epoxidation (pre-)catalyst 1 bearing an equatorial macrocyclic tetra N-heterocyclic carbene and two trans axial labile acetonitrile ligands is reported. NMR spectroscopy and SC-XRD indicate a considerable π-backdonation from the iron(II) centres to the isocyanide ligand(s). The impact of isocyanide substitution on the electronic features of the complexes is studied by cyclic voltammetry revealing a significant increase in half-cell potential assignable to the reversible Fe(II)/Fe(III) redox couple with an increasing number of isocyanides as a result of their π-accepting properties: E_1/2=0.15 V (1), E_1/2=0.35 V (1 a), E_1/2=0.44 V (1 b).

Original language	English
Pages (from-to)	1896-1902
Number of pages	7
Journal	Chemistry - An Asian Journal
Volume	15
Issue number	12
DOIs	https://doi.org/10.1002/asia.202000214
State	Published - 17 Jun 2020

Keywords

N-heterocyclic carbene
cyclic voltammetry
electronic finetuning
isocyanide
non-heme iron complexes

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10.1002/asia.202000214

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title = "Electronic Finetuning of a Bio-inspired Iron(II) tetra-NHC Complex by trans Axial Isocyanide Substitution",

abstract = "The synthesis of trans axially substituted mono- (1 a) and bis(tert-butylisocyanide) (1 b) derivatives of the highly active homogeneous bio-inspired iron(II) olefin epoxidation (pre-)catalyst 1 bearing an equatorial macrocyclic tetra N-heterocyclic carbene and two trans axial labile acetonitrile ligands is reported. NMR spectroscopy and SC-XRD indicate a considerable π-backdonation from the iron(II) centres to the isocyanide ligand(s). The impact of isocyanide substitution on the electronic features of the complexes is studied by cyclic voltammetry revealing a significant increase in half-cell potential assignable to the reversible Fe(II)/Fe(III) redox couple with an increasing number of isocyanides as a result of their π-accepting properties: E1/2=0.15 V (1), E1/2=0.35 V (1 a), E1/2=0.44 V (1 b).",

keywords = "N-heterocyclic carbene, cyclic voltammetry, electronic finetuning, isocyanide, non-heme iron complexes",

author = "Schlagintweit, \{Jonas F.\} and Carolin Hintermeier and Anneser, \{Markus R.\} and Esslinger, \{Eva Maria H.J.\} and Stefan Haslinger and K{\"u}hn, \{Fritz E.\}",

note = "Publisher Copyright: {\textcopyright} 2020 Wiley-VCH Verlag GmbH \& Co. KGaA, Weinheim",

year = "2020",

month = jun,

day = "17",

doi = "10.1002/asia.202000214",

language = "English",

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pages = "1896--1902",

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T1 - Electronic Finetuning of a Bio-inspired Iron(II) tetra-NHC Complex by trans Axial Isocyanide Substitution

AU - Schlagintweit, Jonas F.

AU - Hintermeier, Carolin

AU - Anneser, Markus R.

AU - Esslinger, Eva Maria H.J.

AU - Haslinger, Stefan

AU - Kühn, Fritz E.

PY - 2020/6/17

Y1 - 2020/6/17

N2 - The synthesis of trans axially substituted mono- (1 a) and bis(tert-butylisocyanide) (1 b) derivatives of the highly active homogeneous bio-inspired iron(II) olefin epoxidation (pre-)catalyst 1 bearing an equatorial macrocyclic tetra N-heterocyclic carbene and two trans axial labile acetonitrile ligands is reported. NMR spectroscopy and SC-XRD indicate a considerable π-backdonation from the iron(II) centres to the isocyanide ligand(s). The impact of isocyanide substitution on the electronic features of the complexes is studied by cyclic voltammetry revealing a significant increase in half-cell potential assignable to the reversible Fe(II)/Fe(III) redox couple with an increasing number of isocyanides as a result of their π-accepting properties: E1/2=0.15 V (1), E1/2=0.35 V (1 a), E1/2=0.44 V (1 b).

AB - The synthesis of trans axially substituted mono- (1 a) and bis(tert-butylisocyanide) (1 b) derivatives of the highly active homogeneous bio-inspired iron(II) olefin epoxidation (pre-)catalyst 1 bearing an equatorial macrocyclic tetra N-heterocyclic carbene and two trans axial labile acetonitrile ligands is reported. NMR spectroscopy and SC-XRD indicate a considerable π-backdonation from the iron(II) centres to the isocyanide ligand(s). The impact of isocyanide substitution on the electronic features of the complexes is studied by cyclic voltammetry revealing a significant increase in half-cell potential assignable to the reversible Fe(II)/Fe(III) redox couple with an increasing number of isocyanides as a result of their π-accepting properties: E1/2=0.15 V (1), E1/2=0.35 V (1 a), E1/2=0.44 V (1 b).

KW - N-heterocyclic carbene

KW - cyclic voltammetry

KW - electronic finetuning

KW - isocyanide

KW - non-heme iron complexes

UR - https://www.scopus.com/pages/publications/85082775910

U2 - 10.1002/asia.202000214

DO - 10.1002/asia.202000214

M3 - Article

C2 - 32202690

AN - SCOPUS:85082775910

SN - 1861-4728

VL - 15

SP - 1896

EP - 1902

JO - Chemistry - An Asian Journal

JF - Chemistry - An Asian Journal

IS - 12

ER -

Electronic Finetuning of a Bio-inspired Iron(II) tetra-NHC Complex by trans Axial Isocyanide Substitution

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