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Dioxygen Activation by Siloxide Complexes of Chromium(II) and Chromium(IV)
Author(s) -
Schax Fabian,
Bill Eckhard,
Herwig Christian,
Limberg Christian
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201406313
Subject(s) - chromium , chemistry , yield (engineering) , oxidation state , ligand (biochemistry) , diamond , crystallography , photochemistry , stereochemistry , materials science , catalysis , organic chemistry , metallurgy , receptor , biochemistry
The reaction of a tripodal trisilanol with n ‐butyllithium and CrCl 2 results in a dinuclear Cr II complex ( 1 ), which is capable of cleaving O 2 to yield in a unique complex ( 2 ) with an asymmetric diamond core composed of two Cr IV O units. Magnetic susceptibility data reveal significant exchange coupling of Cr II ( S =2) in 1 and large zero‐field splitting for Cr IV ( S =1) in 2 owing to strong spin–orbit coupling of the ground state. The Cr IV O compound can also be generated using PhIO, and evidence was gathered that although it is the stable product isolated after excessive O 2 treatment, it further activates O 2 to yield an intermediate species that oxidizes THF or Me‐THF. By extensive 18 O labeling studies we were able to show, that in the course of this process 18 O 2 exchanges its label with siloxide O atoms of the ligand via terminal oxido ligands.