Synthesis and crystal structure of a pyrroline nitroxide radical, (N-2,2,5,5-tetramethyl-1-oxo-3-pyrroline-3-carbonyl) (N,N′-diisopropyl)urea
Synthesis and crystal structure of a pyrroline nitroxide radical, (N-2,2,5,5-tetramethyl-1-oxo-3-pyrroline-3-carbonyl) (N,N′-diisopropyl)urea
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DOI：
10.1023/a:1014310208644
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发表时间：
2001-06-01
影响因子：
0.8
通讯作者：
Chen, YZ
中科院分区：
文献类型：
--
作者：
Chen, SY;Nie, JJ;Chen, YZ
通过N,N'-二异丙基碳二亚胺(DIC)与2,2,5,5-四甲基-1-氧代-3-吡咯啉3-甲酸(TPCO)在EtOAc溶液中在氮气氛下反应合成包含稳定硝基氧自由基的标题化合物。从1:1 EtOAc/己烷中，该化合物在三斜空间群P (1)中结晶，在bar上，a = 11.078(2)。 b = 11.970(2)、c = 15.746(3) 埃、alpha = 105.41(3)、beta = 103.47(3)、gamma = 106.52(3) 度和 Z = 4。在不对称单元中，两个分子以相似的键距和角度彼此组装，但显示出晶体学上独立的构象。除了母体脲中显示的部分双 C=N 键之外，在标题化合物中观察到正常的单 C-N 键。 1.26 埃的较长 N-O 距离意味着 N 和 O 原子之间存在单电子 7 键，这可以稳定自由基分子。
The title compound including a stable nitroxide radical was synthesized by a reaction of N,N'-diisopropylcarbondiimide (DIC) with 2,2,5,5-tetramethyl-1-oxo-3-pyrroline3-carboxylic acid (TPCO) in an EtOAc solution under nitrogen atmosphere. From 1:1 EtOAc/hexane the compound crystallizes in triclinic space group P (1) over bar with a = 11.078(2). b = 11.970(2), c = 15.746(3) Angstrom, alpha = 105.41(3), beta = 103.47(3), gamma = 106.52(3)degrees, and Z = 4. In an asymmetric unit two molecules assemble with each other in similar bond distances and angles but show crystallographically independent conformation. A normal single C-N bond is observed in the title compound, other than the partial double C=N bond shown in the parent urea. A longer N-O distance of 1.26 Angstrom implies the existence of a single electron 7 bond between N and O atoms, which stabilizes the radical molecule.