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Copper(i)- and copper(0)-promoted homocoupling and homocoupling–hydrodehalogenation reactions of dihalogenoclathrochelate precursors for C–C conjugated iron(ii) bis-cage complexesстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 марта 2017 г.
- Авторы: Varzatskii Oleg A., Shul’ga Sergey V., Belov Alexander S., Novikov Valentin V., Dolganov Alexander V., Vologzhanina Anna V., Voloshin Yan Z.
- Журнал: Dalton Transactions
- Том: 43
- Номер: 48
- Год издания: 2014
- Издательство: Royal Society of Chemistry
- Местоположение издательства: United Kingdom
- Первая страница: 17934
- Последняя страница: 17948
- DOI: 10.1039/c4dt01557f
- Аннотация: Iron(II) dibromo- and diiodoclathrochelates undergo copper(I)-promoted reductive homocoupling in HMPA at 70–80 °C leading to C–C conjugated dibromo- and diiodo-bis-clathrochelates in high yields. Under the same conditions, their dichloroclathrochelate analog does not undergo the same homocoupling reaction, so the target dichloro-bis-cage product was obtained in high yield via dimerization of its heterodihalogenide iodochloromonomacrobicyclic precursor. The use of NMP as a solvent at 120–140 °C gave the mixture of bis-clathrochelates resulting from a tandem homocoupling–hydrodehalogenation reaction: the initial acetonitrile copper(I) solvato-complex at a high temperature underwent re-solvatation and disproportionation leading to Cu(II) ions and nano-copper, which promoted the hydrodehalogenation process even at room temperature. The most probable pathway of this reaction in situ includes hydrodehalogenation of the already formed dihalogeno-bis-clathrochelate via the formation of reduced anion radical intermediates. As a result, chemical transformations of the iron(II) dihalogenoclathrochelates in the presence of an acetonitrile copper(I) solvato-complex were found to depend both on the nature of halogen atoms in their ribbed chelate fragments and on reaction conditions (i.e. solvent and temperature). The C–C conjugated iron(II) dihalogeno-bis-clathrochelates easily undergo nucleophilic substitution with various N,S-nucleophiles giving ribbed-functionalized bis-cage species. These iron(II) complexes were characterized by elemental analysis, MALDI-TOF mass spectrometry, IR, UV-Vis, 1H and 13C NMR spectroscopy, and by X-ray diffraction; their electrochemical properties were studied by cyclic voltammetry. The isomeric shift values in 57Fe Mössbauer spectra of such cage compounds allowed identifying them as low-spin iron(II) complexes, while those of the quadrupole splitting are the evidence for a significant TP distortion of their FeN6-coordination polyhedra. As follows from CV data, the C–C conjugated iron(II) bis-clathrochelates undergo stepwise electrochemical reduction and oxidation giving mixed-valence FeIIFeI and FeIIFeIII bis-cage intermediates.
- Добавил в систему: Вологжанина Анна Владимировна