A Dimeric Hydride-Bridged Complex with Geometrically Distinct Iron Centers Giving Rise to an S = 3 Ground State.

Authors :: Hickey AK
Greer SM
Valdez-Moreira JA
Lutz SA
Pink M
DeGayner JA
Harris TD
Hill S
Telser J
Smith JM
Source :: Journal of the American Chemical Society [J Am Chem Soc] 2019 Jul 31; Vol. 141 (30), pp. 11970-11975. Date of Electronic Publication: 2019 Jul 19.
Publication Year :: 2019
Abstract: Structural and spectroscopic characterization of the dimeric iron hydride complex [Ph <subscript>2</subscript> B( <superscript>t</superscript> BuIm) <subscript>2</subscript> FeH] <subscript>2</subscript> reveals an unusual structure in which a tetrahedral iron(II) site ( S = 2) is connected to a square planar iron(II) site ( S = 1) by two bridging hydride ligands. Magnetic susceptibility reveals strong ferromagnetic coupling between iron centers, with a coupling constant of J = +110(12) cm <superscript>-1</superscript> , to give an S = 3 ground state. High-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy confirms this model. A qualitative molecular orbital analysis of the electronic structure, as supported by electronic structure calculations, reveals that the observed spin configuration results from the orthogonal alignment of two geometrically distinct four-coordinate iron fragments held together by highly covalent hydride ligands.

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