Synthesis and Characterization of Alkoxide-Bridged Heterometallic Clusters of Cerium and Copper

• Published in: Inorganic chemistry 2019-10, Vol.58 (19), p.12565-12572
• Main Authors: Tsurugi, Hayato, Ikeda, Yuri, Shinohara, Koichi, Shirase, Satoru, Toya, Nozomi, Tanaka, Shinji, Mashima, Kazushi
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b01213

We prepared alkoxide-bridged heterometallic clusters of cerium and copper by the complexation of two metal alkoxides: treatment of Ce­(O t Bu)4 with [Cu­(O t Bu)]4 in a 1:1 metal ratio produced an alkoxide-bridged tetranuclear cluster, Ce2Cu2(O t Bu)10 (1). Upon adding 4-substituted pyridine derivatives to complex 1, trinuclear clusters, Ce2Cu­(O t Bu)9(L) (2a: L = DMAP (4-dimethylaminopyridine); 2b: L = BPY (4,4′-bipyridine)), were obtained along with the release of 0.25 equiv of [Cu­(O t Bu)]4, in which a three-coordinated copper center was involved. In contrast, reaction of 1 with 4 equiv of 2,6-dimethylphenylisocyanide (XylNC) and 0.5 equiv of [Cu­(O t Bu)]4 resulted in the selective formation of CeCu2(O t Bu)6(CNXyl)2 (3). In addition, Ce2K­(O t Bu)9 was used for complexation with CuCl2 by salt-elimination, giving Ce2CuCl­(O t Bu)9 (4) including a five-coordinated copper center. These complexes 1–4 were characterized by crystal structure determination as well as cyclic voltammetry of 1, 2a, and 4. The cyclic voltammogram of 4 in CH2Cl2 and THF suggested that reorganization of the coordination sphere around the copper center was observed for 4 during the Cu­(I/II) redox processes assisted by the coordination of THF.