Open AccessMasked Radicals: Iron Complexes of Trityl, Benzophenone, and Phenylacetylene
Author(s) -
K. Cory MacLeod,
Ida M. DiMucci,
Edward P. Zovinka,
Sean F. McWilliams,
Brandon Q. Mercado,
Kyle M. Lancaster,
Patrick L. Holland
Publication year - 2019
Publication title -
organometallics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.231
H-Index - 172
eISSN - 1520-6041
pISSN - 0276-7333
DOI - 10.1021/acs.organomet.9b00534
Subject(s) - chemistry , phenylacetylene , benzophenone , photochemistry , radical , ligand (biochemistry) , acceptor , unpaired electron , alkyne , molecular orbital , crystallography , molecule , organic chemistry , catalysis , biochemistry , physics , receptor , condensed matter physics
We report the first Fe─CPh 3 complex, and show that the long Fe─C bond can be disrupted by neutral π-acceptor ligands (benzophenone and phenylacetylene) to release the triphenylmethyl radical. The products are formally iron(I) complexes, but X-ray absorption spectroscopy coupled with density functional and multireference ab initio calculations indicates that the best description of all the complexes is iron(II). In the formally iron(I) complexes, this does not imply that the π-acceptor ligand has radical character, because the iron(II) description arises from doubly-occupied frontier molecular orbitals that are shared equitably by the iron and the π-acceptor ligand, and the unpaired electrons lie on the metal. Despite the lack of substantial radical character on the ligands, alkyne and ketone fragments can couple to form a high-spin iron(III) complex with a cyclized metalladihydrofuran core.