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Issue 27, 2016
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Multi-electron redox processes at a Zr(IV) center facilitated by an appended redox-active cobalt-containing metalloligand

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Abstract

The reactivity of a reduced heterobimetallic Co−I/ZrIV complex, (tBuNC)Co(iPr2PNMes)3Zr(THF) (2), with a series of azido and diazo reagents is explored to demonstrate the feasibility of facilitating two-electron redox processes at a formally d0 Zr(IV) center using the appended Co fragment exclusively as an electron-reservoir. Addition of mesityl or adamantyl azide to 2 affords the terminal (tBuNC)Co(iPr2PNMes)3Zr[triple bond, length as m-dash]NMes (3) and bridging (tBuNC)Co(iPr2PNMes)2(μ-NAd)Zr(iPr2PNMes) (4) CoI/ZrIV imido products, respectively. Similarly, diphenyldiazomethane reacts with 2 to afford the terminal Ph2CN22−-bound product (tBuNC)Co(iPr2PNMes)3Zr[triple bond, length as m-dash]N–N[double bond, length as m-dash]CPh2 (5) via a two-electron oxidation of the Co center. Thermolysis of 5 results in a structural rearrangement to the diazomethane-bridged isomer (tBuNC)Co(iPr2PNMes)2(μ-N2CPh2)Zr(iPr2PNMes) (6). In contrast, treatment of 2 with 0.5 equivalents of the conjugated diazo reagent ethyl diazoacetate affords a tetranuclear ZrIV/Co0 complex, (tBuNC)Co(iPr2PNMes)3Zr(μ2–κ1-O-η2-N,N-OC(OEt)CHN2)Zr(MesNPiPr2)3Co(CNtBu) (7), bridged through enolate and η2-bound diazo functionalities.

Graphical abstract: Multi-electron redox processes at a Zr(iv) center facilitated by an appended redox-active cobalt-containing metalloligand

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Publication details

The article was received on 18 Apr 2016, accepted on 14 Jun 2016 and first published on 16 Jun 2016


Article type: Paper
DOI: 10.1039/C6DT01498D
Citation: Dalton Trans., 2016,45, 11182-11190
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    Multi-electron redox processes at a Zr(IV) center facilitated by an appended redox-active cobalt-containing metalloligand

    J. P. Krogman, M. W. Bezpalko, B. M. Foxman and C. M. Thomas, Dalton Trans., 2016, 45, 11182
    DOI: 10.1039/C6DT01498D

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