A Heterobimetallic Superoxide Complex formed through O sub(2) Activation between Chromium(II) and a Lithium Cation

• Published in: Angewandte Chemie International Edition Vol. 54; no. 4; pp. 1352 - 1356
• Main Authors: Schax, Fabian, Suhr, Simon, Bill, Eckhard, Braun, Beatrice, Herwig, Christian, Limberg, Christian
• Format: Journal Article
• Language: English
• Published: 01.01.2015
• Subjects: Activation; Cations; Chromates; Chromium; Crystal structure; Ligands; Lithium; Oxides
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201409294

The reaction of 1,1,3,3-tetraphenyl-1,3-disiloxandiol (LH sub(2)) with n-butyllithium and CrCl sub(2) results in a mononuclear chromium(II) complex (1) that further reacts with O sub(2) at low temperatures to yield a mononuclear chromium(III) superoxide complex [L sub(2)CrO sub(2)(THF)][Li sub(2)(THF) sub(3)] (2). The crystal structure revealed that the chromium superoxido entity is stabilized by the coordination to an adjacent lithium cation. Complex 2 thus contains an unprecedented heterobimetallic [Cr super(III)( mu -O sub(2))Li super(+)] core; beyond this it is the first chromium superoxide for which a temperature-dependent magnetic characterization could be achieved, and the first structurally characterized representative with chromium in an exclusive O-donor environment. A superoxide in an oxide environment: A heterobimetallic superoxide was accessed by reaction of a mononuclear lithium siloxido chromate(II) with O sub(2) at low temperatures to yield a mononuclear chromium(III) superoxide complex. The crystal-structure and spectroscopic data reveal that the superoxido ligand interacts with an adjacent lithium cation, which may have aided the O sub(2) activation.