Cerium(IV) Hexanuclear Clusters from Cerium(III) Precursors: Molecular Models for Oxidative Growth of Ceria Nanoparticles. Issue 38 (31st July 2015)

• Record Type: Journal Article
• Authors: Mathey, Laurent; Paul, Mitali; Copéret, Christophe; Tsurugi, Hayato; Mashima, Kazushi
• Is Part Of: Chemistry. Volume 21:Issue 38(2015)
• Page Start: 13454
• Page End: 13461
• Publication Date: 2015-07-31
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201501731
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>Reactions of cerium(III) nitrate, Ce(NO<sub>3</sub>)<sub>3</sub>⋅6 H<sub>2</sub>O, with different carboxylic acids, such as pivalic acid, benzoic acid, and 4‐methoxybenzoic acid, in the presence of a tridentate <italic>N</italic>, <italic>N</italic>, <italic>N</italic>‐donor ligand, diethylenetriamine (L<sup>1</sup>), under aerobic conditions yielded the corresponding cerium hexamers Ce<sub>6</sub>O<sub>8</sub>(O<sub>2</sub>C<italic>t</italic>Bu)<sub>8</sub>(L<sup>1</sup>)<sub>4</sub> (<bold>1</bold>), Ce<sub>6</sub>O<sub>8</sub>(O<sub>2</sub>CC<sub>6</sub>H<sub>5</sub>)<sub>8</sub>(L<sup>1</sup>)<sub>4</sub> (<bold>2</bold>), and Ce<sub>6</sub>O<sub>8</sub>(O<sub>2</sub>CC<sub>6</sub>H<sub>4</sub>‐4‐OCH<sub>3</sub>)<sub>8</sub>(L<sup>1</sup>)<sub>4</sub> (<bold>3</bold>). Hexamers <bold>1</bold>, <bold>2</bold>, and <bold>3</bold> contain the same octahedral Ce<sup>IV</sup><sub>6</sub>O<sub>8</sub> core, in which all interstitial oxygen atoms are connected by μ<sub>3</sub>‐oxo bridging ligands. In contrast, treatment of the Ce<sup>IV</sup> precursor (NH<sub>4</sub>)<sub>2</sub>Ce(NO<sub>3</sub>)<sub>6</sub> (CAN) with pivalic acid and the ligand L<sup>1</sup> under the same conditions afforded Ce<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub>(O<sub>2</sub>C<italic>t</italic>Bu)<sub>12</sub>(L<sup>1</sup>)<sub>2</sub> (<bold>4</bold>), exhibiting a deformed octahedral Ce<sup>IV</sup><sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub> core containing μ<sub>3</sub>‐oxo and μ<sub>3</sub>‐hydroxo moieties in defined positions. In contrast to the formation of <bold>1</bold>–<bold>3</bold>, the use of <italic>N</italic>‐methyldiethanolamine (L) in the reaction with Ce(NO<sub>3</sub>)<sub>3</sub>⋅6 H<sub>2</sub>O and pivalic acid afforded a previously reported Ce<sup>III</sup> dinuclear cluster, Ce<sub>2</sub>(O<sub>2</sub>C<italic>t</italic>Bu)<sub>6</sub>L<sub>2</sub>, even in the presence of dioxygen. ESI‐MS analysis of the reaction mixture clearly indicated the importance of the ligand L<sup>1</sup> in promoting oxidation of the Ce<sup>III</sup> aggregates, [Ce<sub><italic>n</italic></sub>(O<sub>2</sub>C<italic>t</italic>Bu)<sub>3<italic>n</italic></sub>(L<sup>1</sup>)<sub>2</sub>], which is necessary for the formation of Ce<sup>IV</sup> hexamers.</p> </abstract>