Coordination Chemistry of Proton. In Situ Synthesis and X-Ray Structural Analysis of 2-Hydroxyethanaminium Picrate, HOCH<sub>2</sub>CH<sub>2</sub>NH<sub>3</sub><sup>+</sup>·C<sub>6</sub>H<sub>2</sub>N<sub>3</sub>O<sub>7</sub><sup>−</sup>
作者:Narinder S. Poonia、Ramesh Chandra、W. S. Sheldrick
DOI:10.1246/bcsj.63.1512
日期:1990.5
2-Hydroxyethanaminium picrate, HOCH2CH2NH3+·C6H2N3O7−, is prepared through a metathetical reaction of Mg(Pic)2 and HOCH2CH2NH2 (2-aminoethanol, MEA) in ethanol through in situ generation of HPic. Orange yellow crystals (MEAH+Pic−) (mp 163°C) of the “Salt” are produced alongwith the colorless Mg(CH2NH2CH2O−)2, even when MEA is less than 1:1 with respect to Mg(Pic)2. The crystals are monoclinic, space group P21/c, a=11.797(4), b=14.288(3), c=7.124(2) Å, β=97.63(2)°, Z=4, Dcal=1.62 g cm−3. Structural analysis from the 1617 reflection data (R=0.059, Rw=0.056) reveals that the picric acid proton is formally transferred to the MEA nitrogen (N–H, 0.968 Å) and is merely bonded to the phenoxide of Pic (H···O−, 1.951 Å) and weakly also to an oxygen of o-nitro group of the anion (H···ONO, 2.379 Å). The transferred proton becomes an integral part of the cation MEAH+ and completes the fourth covalent bond of the sp3 N of MEA, and does not show any special affinity for the anionic oxygen of Pic; the N–H···O− (142.8°) and N–H···ONO (141.6°) angles are closely comparable.
2-羟基乙胺苦味酸盐(HOCH2CH2NH3+·C6H2N3O7−)是通过Mg(Pic)2和HOCH2CH2NH2(2-氨基乙醇,MEA)在乙醇中的原位生成HPic的复分解反应制备的。即使MEA与Mg(Pic)2的比例小于1:1,也会生成“盐”的橙黄色晶体(MEAH+Pic−)(熔点163°C)和无色的Mg(CH2NH2CH2O−)2。晶体为单斜晶系,空间群P21/c,a=11.797(4),b=14.288(3),c=7.124(2) Å,β=97.63(2)°,Z=4,Dcal=1.62 g cm−3。根据1617反射数据(R=0.059,Rw=0.056)进行的结构分析显示,苦味酸质子被正式转移到MEA氮(N–H,0.968 Å)上,仅与Pic的苯氧基(H···O−,1.951 Å)结合,并与阴离子的邻硝基基团的氧(H···ONO,2.379 Å)