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A bis ‐Pyrazolate Pincer on Reduced Cr Deoxygenates CO 2 : Selective Capture of the Derived Oxide by Cr II
Author(s) -
Labrum Nicholas S.,
Chen ChunHsing,
Caulton Kenneth G.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901134
Subject(s) - pincer movement , chemistry , oxide , paramagnetism , crystallography , pyridine , stoichiometry , ligand (biochemistry) , selectivity , carbonate , pincer ligand , inorganic chemistry , electron paramagnetic resonance , stereochemistry , medicinal chemistry , catalysis , nuclear magnetic resonance , organic chemistry , physics , biochemistry , receptor , quantum mechanics
Abstract Reduction of the bis ‐(pyrazolyl)pyridine complex [LCr] 2 with stoichiometric KC 8 in THF produces a species that is reactive with CO 2 to produce an aggregate composed of paramagnetic K 2 L 2 Cr 2 (CO 3 ) linked by KCl into a product of formula [K 2 L 2 Cr 2 (CO 3 )] 4 ⋅2KCl. X‐ray diffraction reveals a pincer hydrocarbon exterior and an inorganic interior composed of K + , Cl − and carbonate oxygens. Every Cr is five coordinate and square pyramidal, with the axial N donor weakly bonded to Cr due to the Jahn–Teller effect of a high spin d 4 configuration. Reaction with 13 CO 2 confirms that carbonate here is derived from CO 2 , that oxide is derived from CO 2 , and that CO is indeed released, since it is not a competent ligand to Cr II . Guiding principles for selectivity in CO 2 reduction are deduced from the diverse successful molecular constructs to date.