Issue 39, 2020

Redox chemistry and H-atom abstraction reactivity of a terminal zirconium(iv) oxo compound mediated by an appended cobalt(i) center

Abstract

The reactivity of the terminal zirconium(IV) oxo complex, O[triple bond, length as m-dash]Zr(MesNPiPr2)3CoCNtBu (2), is explored, revealing unique redox activity imparted by the pendent redox active cobalt(I) center. Oxo complex 2 can be chemically reduced using Na/Hg or Ph3C to afford the ZrIV/Co0 complexes [(μ-Na)OZr(MesNPiPr2)3CoCNtBu]2 (3) and Ph3COZr(MesNPiPr2)3CoCNtBu (4), respectively. Based on the cyclic voltammogram of 2, Ph3˙ should not be sufficiently reducing to achieve the chemical reduction of 2, but sufficient driving force for the reaction is provided by the nucleophilicity of the terminal oxo fragment and its affinity to bind Ph3C+. Accordingly, 2 reacts readily with [Ph3C][BPh4] and Ph3CCl to afford [Ph3COZr(MesNPiPr2)3CoCNtBu][BPh4] ([5][BPh4]) and Ph3COZr(MesNPiPr2)3CoCl (6), respectively. The chemical oxidation of 2 is also investigated, revealing that oxidation of 2 is accompanied by immediate hydrogen atom abstraction to afford the hydroxide complex [HOZr(MesNPiPr2)3CoCNtBu]+ ([9]+). Thus it is posited that the transient [OZr(MesNPiPr2)3CoCNtBu]+ [2]+ cation generated upon oxidation combines the basicity of a nucleophilic early metal oxo fragment with the oxidizing power of the appended cobalt center to facilitate H-atom abstraction.

Graphical abstract: Redox chemistry and H-atom abstraction reactivity of a terminal zirconium(iv) oxo compound mediated by an appended cobalt(i) center

Supplementary files

Article information

Article type
Edge Article
Submitted
02 8 2020
Accepted
04 9 2020
First published
04 9 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2020,11, 10729-10736

Redox chemistry and H-atom abstraction reactivity of a terminal zirconium(IV) oxo compound mediated by an appended cobalt(I) center

H. Zhang, G. P. Hatzis, D. A. Dickie, C. E. Moore and C. M. Thomas, Chem. Sci., 2020, 11, 10729 DOI: 10.1039/D0SC04229C

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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