Preparation, structure and vibrational spectrum of the dimethylmethyleniminium ion, including the role of cationic polymers in its formation
作者:George R. Clark、Graeme L. Shaw、Peter W. J. Surman、Michael J. Taylor、Derek Steele
DOI:10.1039/ft9949003139
日期:——
Crystalline [(CH3)2NCH2]X (1X, where X = Br or I) results from the reaction of N,N,N′,N′-tetra-methylmethylenediamine with CH2Br2 or CH2I2 at room temperature. The structure of 1Br has been determined by X-ray crystallography. The crystals are orthorhombic, a= 6.262(2)Å, b= 7.428(3)Å, c= 5.651(2)Å, z= 2, space group Pmmn. The final R= 0.037 for 484 observed reflections. The dimethylmethyleniminium cation, 1, has crystallographically imposed mm2 symmetry, with the CN bond distance 1.263(5)Å, C—N bond distance 1.474(4)Å, and the CH3—N—CH3 angle 114.4(4)°. The Raman spectrum of 1, investigated as the bromide and iodide salts, and supplemented by IR data for 12SnBr6, has been fully assigned with the aid of ab initio calculations using the 3-21G** basis at the SCF and MP2 levels. Isotopic labelling experiments which generate [(CH3)2NCD2]+ from CD2l2 have been used in conjunction with NMR and Raman measurements to investigate the reactions leading to the iminium salt. The intermediate [Me2NCH2NMe2CH2NMe2]+ and a cationic polymer [Me2N(CH2NMe2)nCH2NMe2]n+ are implicated in the reactions which form the basis of the synthesis of [(CH3)2NCH2]l.
晶体[(CH3)2NCH2]X(1X,其中X=Br或I)是通过N,N,N',N'-四甲基亚甲基二胺与CH2Br2或CH2I2在室温下反应得到的。通过X射线晶体学确定了1Br的结构。晶体为正交晶系,a=6.262(2)Å,b=7.428(3)Å,c=5.651(2)Å,z=2,空间群为Pmmn。对于484个观测反射,最终的R值为0.037。二甲基亚甲基亚胺阳离子1具有结晶学上强加的mm2对称性,其中CN键距离为1.263(5)Å,C—N键距离为1.474(4)Å,CH3—N—CH3角度为114.4(4)°。通过对溴化物和碘化物盐进行了拉曼光谱研究,并补充了1/2SnBr6的红外数据,通过使用3-21G**基组在SCF和MP2水平上进行从头计算,对其进行了全面分配。结合NMR和拉曼测量,利用从CD2l2生成[(CH3)2NCD2]+的同位素标记实验,研究了导致亚胺盐的反应。中间体[Me2NCH2NMe2CH2NMe2]+和一个阳离子聚合物[Me2N(CH2NMe2)nCH2NMe2]n+是形成[(CH3)2NCH2]I的反应的基础。