Copper(I) and -(II) Complexes of Neutral and Deprotonated N-(2,6-Diisopropylphenyl)-3-[bis(2-pyridylmethyl)amino]propanamide

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• 作者：Timothy E. Patten ; Christina Troeltzsch ; and Marilyn M. Olmstead
• 刊名：Inorganic Chemistry
• 出版年：2005
• 出版时间：December 12, 2005
• 年：2005
• 卷：44
• 期：25
• 页码：9197 - 9206
• 全文大小：221K
• 年卷期：v.44,no.25(December 12, 2005)
• ISSN：1520-510X

文摘

As part of a study of atom-transfer radical polymerization (ATRP) catalysts, four new copper(I) and -(II) compoundsof a new monoanionic, tripodal tetradentate ligand, N-(2,6-diisopropylphenyl)-3-[bis(2-pyridylmethyl)amino]propanamide(DIPMAP), were prepared. Ligand synthesis followed from the addition-elimination reaction of 2,6-diisopropylanilinewith acryloyl chloride and then a Lewis acid catalyzed Michael addition of bis(2-pyridylmethyl)amine to this product.The ligand was complexed to CuCl to yield monomeric Cu(DIPMAP)Cl featuring an intramolecular hydrogen bondbetween the free amide hydrogen and the coordinated chloride ligand. Deprotonation of the amide hydrogen inCu(DIPMAP)Cl using n-BuLi led to the incorporation of LiCl in the resulting product, Li₂Cu₂(DIPMAP)₂Cl₂. Thiscomplex exhibited an unusual dimeric structure, with the amine nitrogens of one ligand coordinated to a lithium ion,the amide oxygen of the same ligand bridging between the lithium ions, and the amidate nitrogen of that ligandcoordinated to a CuCl unit that has a structure analogous to dihalocuprate ions. Deprotonation of Cu(DIPMAP)Clusing KO^tBu yielded an alkali-metal chloride free product, Cu₂(DIPMAP)₂, that also exhibited a dimeric structure inwhich the three amine nitrogens of one ligand were coordinated to one Cu^I ion and the amidate nitrogen of thesame ligand was coordinated to the other Cu^I ion. Cu₂(DIPMAP)₂ was effective in abstracting halogen atoms fromorganic halides, but in the attempted ATRP of tert-butyl acrylate, molecular weight versus conversion behaviorreminiscent of a redox-initiated polymerization was observed. DIPMAP was coordinated to CuBr₂ to yield[Cu(DIPMAP)Br]Br with a square-pyramidal structure. The amide hydrogen in this complex could be deprotonatedusing KO^tBu to form complex [DIPMAP]CuBr (6). Spectral characterization of complex 6 confirmed deprotonationof the ligand and that it most likely had an axially distorted trigonal-bipyramidal structure, although crystals suitablefor X-ray analysis could not be obtained. Solution oxidation of Cu₂(DIPMAP)₂ using CBr₄ yielded a product, complex4, whose spectral signatures did not match those of complex 6. The dimeric structure of Cu₂(DIPMAP)₂ might bea significant contributing factor to the slow rate of deactivation observed in atom-transfer reactions using Cu₂(DIPMAP)₂as the catalyst.