title: Electronic Structures of Reduced and Superreduced Ir2(1,8-diisocyanomenthane)4n+Complexes.
abstract: Molecular and electronic structures of Ir2(1,8-diisocyanomenthane)4n+(Ir(dimen)n+) complexes have been investigated by DFT for n = 2, 1, 0 (abbreviated 2+, 1+, 0). Calculations reproduced the experimental structure of 2+, ν(C≡N) IR, and visible absorption spectra of all three oxidation states, as well as the EPR spectrum of 1+. We have shown that the two reduction steps correspond to successive filling of the Ir-Ir pσ orbital. Complexes 2+ and 1+ have very similar structures with 1+ having a shorter Ir-Ir distance. The unpaired electron density in 1+ is delocalized along the Ir-Ir axis and over N atoms of the eight C≡N- ligands. The second reduction step 1+ → 0 changes the Ir(CN-)4coordination geometry at each Ir site from approximately planar to seesaw whereby one -N≡C-Ir-C≡N- moiety is linear and the other bent at the Ir (137°) as well as N (146°) atoms. Although complex 0 is another example of a rare (pσ)2dimetallic species (after [Pt2(μ-P2O5(BF2)2)4]6-, J. Am. Chem. Soc. 2016, 138, 5699), the redistribution of lower lying occupied molecular orbitals increases electron density predominantly at the bent C≡N- ligands whose N atoms are predicted to be nucleophilic reaction centers.
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences , Dolejškova 3, 182 23 Prague, Czech Republic.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Záliš
authors.affiliation: Beckman Institute, California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Bryan M
authors.initials: BM
authors.lastname: Hunter
authors.affiliation: Beckman Institute, California Institute of Technology , Pasadena, California 91125, United States.
authors.forename: Harry B
authors.initials: HB
authors.lastname: Gray
authors.affiliation: J. Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences , Dolejškova 3, 182 23 Prague, Czech Republic.|School of Biological and Chemical Sciences, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom.
authors.forename: Antonín
authors.identifier: http://orcid.org/0000-0002-6413-8311
authors.initials: A
authors.lastname: Vlček