| Autor: |
Lindley, Brian M., van Alten, Richt S., Finger, Markus, Schendzielorz, Florian, Würtele, Christian, Miller, Alexander J. M., Siewert, Inke, Schneider, Sven |
| Zdroj: |
Journal of the American Chemical Society; June 2018, Vol. 140 Issue: 25 p7922-7935, 14p |
| Abstrakt: |
A comprehensive mechanistic study of N2activation and splitting into terminal nitride ligands upon reduction of the rhenium dichloride complex [ReCl2(PNP)] is presented (PNP–= N(CH2CH2PtBu2)2–). Low-temperature studies using chemical reductants enabled full characterization of the N2-bridged intermediate [{(PNP)ClRe}2(N2)] and kinetic analysis of the N–N bond scission process. Controlled potential electrolysis at room temperature also resulted in formation of the nitride product [Re(N)Cl(PNP)]. This first example of molecular electrochemical N2splitting into nitride complexes enabled the use of cyclic voltammetry (CV) methods to establish the mechanism of reductive N2activation to form the N2-bridged intermediate. CV data was acquired under Ar and N2, and with varying chloride concentration, rhenium concentration, and N2pressure. A series of kinetic models was vetted against the CV data using digital simulations, leading to the assignment of an ECCEC mechanism (where “E” is an electrochemical step and “C” is a chemical step) for N2activation that proceeds via initial reduction to ReII, N2binding, chloride dissociation, and further reduction to ReIbefore formation of the N2-bridged, dinuclear intermediate by comproportionation with the ReIIIprecursor. Experimental kinetic data for all individual steps could be obtained. The mechanism is supported by density functional theory computations, which provide further insight into the electronic structure requirements for N2splitting in the tetragonal frameworks enforced by rigid pincer ligands. |
| Databáze: |
Supplemental Index |
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