A Polysiloxide Complex with two Chromium(III) η2‐Superoxo Moieties

• Published in: Israel journal of chemistry Vol. 60; no. 10-11; pp. 1057 - 1060
• Main Authors: Wind, Marie‐Louise, Braun‐Cula, Beatrice, Schax, Fabian, Herwig, Christian, Limberg, Christian
• Format: Journal Article
• Language: English
• Published: Haifa Wiley Subscription Services, Inc 01.10.2020
• Subjects: Bonding strength; Chromium; O−O activation; Room temperature; siloxide; superoxo; Transition metals
• ISSN: 0021-2148; 1869-5868
• DOI: 10.1002/ijch.201900119

The isolation and identification of intermediates formed in the course of the activation of dioxygen at transition metal centers reveals important mechanistic insights concerning such processes. We previously reported the reaction of the dinuclear CrII complex [L2Cr2(MeCN)2][Li(MeCN)]2 (L=PhSi(OSiPh2O−)3) (5) with dioxygen, which resulted in the formation of the CrIV oxo complex [L2Cr2O2][Li(THF)2]2 (6), as the final room temperature stable product. Here we now report the isolation and characterization of an intermediate en route to 6, namely the dinuclear CrIII superoxo complex [L2Cr2(O2)2][Li(MeCN)]2 (7). 7 is the first example of a structurally characterized dinuclear CrIII superoxo complex with two independent side‐on bound superoxo ligands. Reactivity studies outline the capability of this superoxo complex to activate weak O−H bonds. A unique example of a dinuclear CrIII superoxo complex with two independent side‐on bound superoxo ligands is reported. This complex was identified as an intermediate in the reaction of a CrII polysiloxide complex with dioxygen. Reactivity studies outline the capability of this superoxo complex to activate weak O−H bonds.