Copper(I) and -(II) complexes of neutral and deprotonated N-(2,6-diisopropylphenyl)-3-[bis(2-pyridylmethyl)amino]propanamide
Copper(I) and -(II) complexes of neutral and deprotonated N-(2,6-diisopropylphenyl)-3-[bis(2-pyridylmethyl)amino]propanamide
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DOI：
10.1021/ic0505697
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发表时间：
2005-12-12
影响因子：
4.6
通讯作者：
Olmstead, MM
中科院分区：
文献类型：
--
作者：
Patten, TE;Troeltzsch, C;Olmstead, MM
作为原子转移自由基聚合（ATRP）催化剂研究的一部分，制备了四种新的铜（I）和一种新的单阴离子三足四齿配体N-（2，6-二异丙基苯基）-3-[双（2-吡啶甲基）氨基]丙酰胺（DIPMAP）的铜（II）化合物。配体的合成是由2，6-二异丙基苯胺与丙烯酰氯的加成-消除反应，然后是刘易斯酸催化的双（2-吡啶基甲基）胺与该产物的迈克尔加成反应。配体络合到CuCl以产生单体Cu（DIPMAP）Cl，其特征在于游离酰胺氢和配位氯配体之间的分子内氢键。使用n-BuLi使Cu（DIPMAP）Cl中的酰胺氢去质子化，导致LiCl并入所得产物Li 2Cu 2（DIPMAP）（2）Cl-2中。该配合物表现出一种不寻常的二聚体结构，其中一个配体的胺氮与锂离子配位，同一配体的酰胺氧在锂离子之间桥接，并且该配体的酰胺化氮与具有类似于二卤代铜酸盐离子的结构的CuCl单元配位。用（KOBU）-Bu-t使Cu（DIPMAP）Cl去质子化，得到不含碱金属氯化物的产物Cu-2（DIPMAP）（2），其也表现出二聚体结构，其中一个配体的三个胺氮与一个Cu-I离子配位，同一配体的酰胺氮与另一个Cu-I离子配位。Cu-2（DIPMAP）（2）可有效地从有机卤化物中提取卤原子，但在丙烯酸叔丁酯的尝试ATRP中，观察到分子量与转化率行为，让人想起氧化还原引发的聚合。DIPMAP与CuBr 2配位生成具有四方锥结构的[Cu（DIPMAP）Br]Br。该配合物中的酰胺氢可被（KOBU）-Bu-t脱质子化形成配合物[DIPMAP]CuBr（6）。络合物6的光谱表征证实了配体的去质子化，并且它最有可能具有轴向扭曲的三角双锥结构，尽管不能获得适合于X射线分析的晶体。使用CBr 4溶液氧化Cu-2（DIPMAP）（2）产生产物，络合物4，其光谱特征与络合物6的光谱特征不匹配。Cu-2（DIPMAP）（2）的二聚体结构可能是使用Cu-2（DIPMAP）（2）作为催化剂的原子转移反应中观察到的缓慢失活速率的重要贡献因素。
As part of a study of atom-transfer radical polymerization (ATRP) catalysts, four new copper(I) and -(II) compounds of 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-diisopropylaniline with 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 bond between the free amide hydrogen and the coordinated chloride ligand. Deprotonation of the amide hydrogen in Cu(DIPMAP)Cl using n-BuLi led to the incorporation of LiCl in the resulting product, Li2Cu2(DIPMAP)(2)Cl-2. This complex 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 ligand coordinated to a CuCl unit that has a structure analogous to dihalocuprate ions. Deprotonation of Cu(DIPMAP)Cl using (KOBu)-Bu-t yielded an alkali-metal chloride free product, Cu-2(DIPMAP)(2), that also exhibited a dimeric structure in which the three amine nitrogens of one ligand were coordinated to one Cu-I ion and the amidate nitrogen of the same ligand was coordinated to the other Cu-I ion. Cu-2(DIPMAP)(2) was effective in abstracting halogen atoms from organic halides, but in the attempted ATRP of tert-butyl acrylate, molecular weight versus conversion behavior reminiscent 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 deprotonated using (KOBu)-Bu-t to form complex [DIPMAP]CuBr (6). Spectral characterization of complex 6 confirmed deprotonation of the ligand and that it most likely had an axially distorted trigonal-bipyramidal structure, although crystals suitable for X-ray analysis could not be obtained. Solution oxidation of Cu-2(DIPMAP)(2) using CBr4 yielded a product, complex 4, whose spectral signatures did not match those of complex 6. The dimeric structure of Cu-2(DIPMAP)(2) might be a significant contributing factor to the slow rate of deactivation observed in atom-transfer reactions using Cu-2(DIPMAP)(2) as the catalyst.