These are preliminary reports that have not been peer-reviewed. They should not be regarded as conclusive, guide clinical practice/health-related behavior, or be reported in news media as established information. For more information, please see our FAQs.
Ni(TAPPy)2_ChemRXiv.pdf (11.11 MB)

Ligand-Centered Electrochemical Processes Enable CO2 Reduction with a Nickel Bis(triazapentadienyl) Complex

submitted on 18.12.2018, 14:41 and posted on 19.12.2018, 15:15 by Zachary Dubrawski, Joshua E. Heidebrecht, Braulio M. Puerta Lombardi, Alexander Hyla, Janina Willkomm, Chase Radford, Jian-Bin Li, Gregory C. Welch, Sathish Ponnurangam, Roland Roesler, Demyan E. Prokopchuk, Warren Piers
We report the synthesis of Ni(TAPPy)2 (TAPPy = 1,3,5-triazapentadienyl-2,4-bis(2-pyridyl)) and its reactivity with CO2 under reducing conditions. Electrochemical reduction of Ni(TAPPy)2 under inert gas reveals that the complex accommodates up to two additional electrons, with DFT calculations indicating that electron density is delocalized almost exclusively onto the TAPPy ligand framework. The singly reduced product [K(crypt)][Ni(TAPPy)2] (crypt = 2.2.2-cryptand) has been synthesized, and its EPR data is consistent with having ligand-based radical anion character. Controlled potential electrolysis experiments reveal that reduced Ni(TAPPy)2 converts CO2 to form CO; however, spectroscopic and computational data indicate that deactivation readily occurs to form Ni(L)(CO)n compounds, CO32-, and carboxylated (RCOO-) ligand decomposition products. This study highlights that redox activity at the ligand can play an important role during the reduction of CO2 using transition metal complexes.


Canada First Excellence Research Fund (CFREF)

Canada Foundation for Innovation (CFI)

Compute Canada / Calcul Canada

Natural Sciences and Engineering Research Council

Find out more...


Email Address of Submitting Author


University of Calgary



ORCID For Submitting Author


Declaration of Conflict of Interest

No conflict of interest to declare