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 ?-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 ?-accepting properties: E1/2 =0.15?V (1), E1/2 =0.35?V (1?a), E1/2 =0.44?V (1?b).

SUBMITTER: Schlagintweit JF 

PROVIDER: S-EPMC7687264 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature