Abstract

To probe the possibility that carbodicarbenes (CDCs) are redox active ligands, all four members of the redox series [Fe(1)2]n+ (n = 2 - 5) were synthesized, where 1 is a neutral tridentate CDC. Through a combination of spectroscopy and DFT calculations, the electronic structure of the pentacation is shown to be [FeIII(1.+)2]5+ (S = (Formula presented.)). That of [Fe(1)2]4+ is more ambiguous, but it has significant contributions from the open-shell singlet [FeIII(1)(1.+)]4+ (S=0). The observed spin states derive from antiferromagnetic coupling of their constituent low-spin iron(III) centres and cation radical ligands. This marks the first time redox activity has been observed for carbones and expands the diverse chemical behaviour known for these ligands. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim