Cu2+, Zn2+, and Ni2+ Complexes of C2-Symmetric Pseudopeptides with an Aromatic Central Spacer

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• 作者：Lingaraju Gorla ; Vicente Martí-Centelles ; Lena Freimuth ; Belén Altava ; M. Isabel Burguete ; Santiago V. Luis
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：August 1, 2016
• 年：2016
• 卷：55
• 期：15
• 页码：7617-7629
• 全文大小：727K
• 年卷期：0
• ISSN：1520-510X

文摘

Two new tetradentate C₂-symmetric pseudopeptidic ligands derived from Val and Phe containing two amino and two amido groups and a central o-substituted aromatic spacer have been prepared. Their complexes with Cu²⁺, Zn²⁺, and Ni²⁺ have been studied by potentiometry, UV–vis spectrophotometry, FT-IR, and ESI-MS. The presence of the aromatic spacer provides Cu²⁺ complexes with stability constants several orders of magnitude higher than those observed for related ligands containing aliphatic central spacers. Besides, the formation of [MH_–2L] complex species is favored. Crystal structures for the corresponding Cu²⁺ and Ni²⁺ have been obtained, revealing the metal atom in an essentially square-planar geometry, although, in several instances, the oxygen atom of an amide carbonyl of a second complex species can act as a fifth coordination site. In the case of Zn²⁺, the only crystal structure obtained displays a square-pyramidal arrangement of the metal center. Finally, preliminary experiments show the catalytic activity of some of these complexes, in particular, Zn²⁺ complexes, for epoxide ring-opening with using aniline as the nucleophile in a ligand accelerated process.