An NMR study of the oxidative degradation of Cp *ir catalysts for water oxidation: Evidence for a preliminary attack on the quaternary carbon atom of the -C-CH3 moiety

Zuccaccia, C., Bellachioma, G., Bolaño, S., Rocchigiani, L., Savini, A. and MacChioni, A. (2012) An NMR study of the oxidative degradation of Cp *ir catalysts for water oxidation: Evidence for a preliminary attack on the quaternary carbon atom of the -C-CH3 moiety. European Journal of Inorganic Chemistry, 2012 (9). pp. 1462-1468. ISSN 1434-1948

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Abstract

The reaction between H2O2 and two water oxidation catalysts {[Cp*Ir(H2O)3](NO3)2 (1, Cp* = pentamethylcyclopentadienyl) and [Cp*Ir(bzpy)(NO3)] (2, bzpy = 2‐benzoylpyridine)} was studied by means of in situ 1D‐ and 2D‐NMR experiments in order to elucidate if catalyst degradation proceeds through the initial functionalization of a quaternary carbon atom (C‐attack) or by hydrogen abstraction (H‐attack) of the Cp* –C–CH3 moiety. It was shown that 1 underwent double functionalization of the –C–CH3 moiety of Cp* leading to the formation of –C(OR)–CH2OR (R = H or OH) in a strictly analogous manner to that previously observed for the reaction of 1 with Ce4+. On the contrary, two new intermediates associated with the oxidative degradation of 2, which are functionalized only at the quaternary carbon atom(s) of the –C–CH3 moiety [–C(OR)–CH3], were intercepted and characterized by NMR spectroscopy. This indicates that the oxidative degradation of water oxidation catalysts, featuring the –Cp* ancillary ligand, likely starts with preferential C‐attack.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
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Depositing User: LivePure Connector
Date Deposited: 19 Jun 2019 07:30
Last Modified: 22 Apr 2020 07:57
URI: https://ueaeprints.uea.ac.uk/id/eprint/71469
DOI: 10.1002/ejic.201100954

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