Electronic Structure of a Diiron Complex: A Multitechnique Experimental Study of [(dppf)Fe(CO) 3]+/0

Mario Winkler; Marc Schnierle; Felix Ehrlich; Kim-Isabelle Mehnert; David Hunger; Alena M Sheveleva; Lukas Burkhardt; Matthias Bauer; Floriana Tuna; Mark R Ringenberg; Joris van Slageren

doi:10.1021/acs.inorgchem.0c03259

Electronic Structure of a Diiron Complex: A Multitechnique Experimental Study of [(dppf)Fe(CO) ₃]^+/0

Inorg Chem. 2021 Mar 1;60(5):2856-2865. doi: 10.1021/acs.inorgchem.0c03259. Epub 2021 Feb 11.

Affiliations

¹ Institute of Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart 70569, Germany.
² Institute of Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart 70569, Germany.
³ Department of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
⁴ Department of Chemistry and Center for Sustainable Systems Design, Paderborn University, Warburger Strasse 100, Paderborn 33098, Germany.

PMID: 33569942
DOI: 10.1021/acs.inorgchem.0c03259

Abstract

Here we explore the electronic structure of the diiron complex [(dppf)Fe(CO)₃]^0/+ [1^0/+; dppf = 1,1'-bis(diphenylphosphino)ferrocene] in two oxidation states by an advanced multitechnique experimental approach. A combination of magnetic circular dichroism, X-ray absorption and emission, high-frequency electron paramagnetic resonance (EPR), and Mössbauer spectroscopies is used to establish that oxidation of 1⁰ occurs on the carbonyl iron ion, resulting in a low-spin iron(I) ion. It is shown that an unequivocal result is obtained by combining several methods. Compound 1⁺ displays slow spin dynamics, which is used here to study its geometric structure by means of pulsed EPR methods. Surprisingly, these data show an association of the tetrakis[3,5-bis(trifluoromethylphenyl)]borate counterion with 1⁺.