Selective Imidazolidine Ring Opening during Complex Formation of Iron(III), Copper(II), and Zinc(II) with a Multidentate Ligand Obtained from 2-Pyridinecarboxaldehyde N-Oxide and Triethylenetet

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• 作者：M. Bog src="http ; //pubs.acs.org/images/entities/ccaron.gif" border="0">a ; P. Baran ; R. Bog src="http ; //pubs.acs.org/images/entities/ccaron.gif" border="0">a ; H. Fuess ; G. Kickelbick ; W. Linert
• 刊名：Inorganic Chemistry
• 出版年：2000
• 出版时间：July 24, 2000
• 年：2000
• 卷：39
• 期：15
• 页码：3205 - 3212
• 全文大小：165K
• 年卷期：v.39,no.15(July 24, 2000)
• ISSN：1520-510X

文摘

The condensation of 2-pyridinecarboxaldehyde N-oxide and triethylenetetramine yields a product with twoimidazolidine rings, as proven by a solid-state X-ray structure analysis as well as by NMR solution spectra. Thisligand, L¹, undergoes a ring-opening reaction on complex formation with Cu(II), yielding [CuL²]²⁺ where L²functions as a pentadentate ligand, containing only one imidazolidine ring. On complexation with Zn(II) andFe(III), both rings are opened and the complexes [ZnL³]²⁺ and [FeL³]³⁺ with a hexadentate L³ ligand are formed.The recrystallization of [ZnL³]²⁺ from DMSO solution results in the complex [ZnL¹(DMSO)₂]²⁺ in which L¹behaves as a tetradentate ligand. Thus L¹, L², and L³ are structural isomers with two, one, or no imidazolidinerings, as confirmed by X-ray structure analyses. The intramolecular ring formation is the result of the nucleophilicaddition of the N(amino) group to the electrophilic sp²-hybridized -HC^{ges/gifchars/delta.gif" BORDER=0 >+}=N site. Owing to the absence of thechelate effect on the sp³-hybridized carbon atom belonging to the imidazolidine ring, the ring opening is facilitatedand readily observed upon complex formation with Cu(II), Zn(II), and Fe(III).