• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Mechanistic aspects of the reaction between Br-2 and chalcogenone donors (LE; E = S, Se): Competitive formation of 10-E-3, T-shaped 1 : 1 molecular adducts, charge-transfer adducts, and [(LE)(2)](2+) dications
【24h】

Mechanistic aspects of the reaction between Br-2 and chalcogenone donors (LE; E = S, Se): Competitive formation of 10-E-3, T-shaped 1 : 1 molecular adducts, charge-transfer adducts, and [(LE)(2)](2+) dications

机译：Br-2和硫属激素供体之间反应的机理（LE; E = S，Se）：竞争性形成10-E-3，T形1：1分子加合物，电荷转移加合物和[（LE） （2）]（2+）种指示

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The synthesis and spectroscopic characterisation of the products obtained by treatment of N,N'-dimethyl-imidazolidine-2-thione (1), N,N'-dimethylimidazolidine-2-selone (2), N,N'-dimethylbenzoimidazole-2-thione (3) and N,N'-dimethylbenzoimidazole-2-selone (4) with Br-2 in MeCN are reported, together with the crystal structures of the 10-E-3, T-shaped adducts 2 . Br-2 (12), 3Br(2) (13) and 4 . Br-2 (14). A conductometric and spectrophotometric investigation into the reaction between 1-4 and Br-2, carried out in MeCN, allows the equilibria involved in the formation of the isolated 10-E-3 (E=S, Se) hyper valent compounds to be hypothesised. In order to understand the reasons why S and Se donors can give different product types on treatment with Br-2 and I-2, DFT calculations have been carried out on 1-8, 19 and 20, and on their corresponding hypothetical [LEX](+) cations (L=organic framework; E= S, Se; X = Br, I), which are considered to be key intermediates in the formation of the different products. The results obtained in terms of NBO charge distribution on [LEX](+) species explain the different behaviour of 1-8, 19 and 20 in their reactions with Br-2 and I-2 fairly well. X-ray diffraction studies show 12-14 to have a T-shaped (10-E-3; E = S, Se) hypervalent chalcogen nature. They contain an almost linear Br-E-Br (E = S, Se) system roughly perpendicular to the average plane of the organic molecules. In 12, the Se atom of each adduct molecule has a short interaction with the Br(1) atom of an adjacent unit, such that the Se atom displays a roughly square planar coordination. The Se-Br distances are asymmetric [2.529(1) vs. 2.605(1) Angstrom]. the shorter distance being that with the Br(1) atom involved in the short intermolecular contact. In contrast, in the molecular adducts 13 and 14, which lie on a two-fold crystallographic axis, the Br-E-Br system is symmetric and no short intermolecular interactions involving chalcogen and bromine atoms are observed. The adducts are arranged in parallel planes; this gives rise to a graphite-like stacking. The new crystalline modification of 10, obtained from acetonitrile solution, confirms the importance of short intermolecular contacts in determining the asymmetry of Br-E-Br (E = S, Se) and I-Se-I groups in hypervalent 10-E-3 compounds. The analogies in the conductometric and spectrophotometric titrations of 1 and 2-4 with Br-2, together with the similarity of the vibrational spectra of 11-14, also imply a T-shaped nature for 11. The vibrational properties of the Br-E-Br (E=S, Se) systems resemble those of the Br-3(-) and IBr2- anions: the Raman spectrum of a symmetric Br-E-Br group shows only one peak near 160 cm(-1), as found for symmetric Br-3(-) and IBr2- anions, while asymmetric Br-E-Br groups also show an antisymmetric Br-E-Br mode at around 190 cm(-1), as observed for asymmetric Br-3(-) and IBr2- ions. Therefore, simple IR and Raman measurements provide a useful tool for distinguishing between symmetric and asymmetric Br-E-Br groups, and hence allow predictions about the crystal packing of these hypervalent chalcogen compounds to be made when crystals of good quality are not available. [References: 76]
机译：通过处理N，N'-二甲基咪唑烷-2-硫酮（1），N，N'-二甲基咪唑烷-2-硒酮（2），N，N'-二甲基苯并咪唑-2处理的产物的合成和光谱表征报道了在MeCN中带有Br-2的-硫酮（3）和N，N'-二甲基苯并咪唑-2-硒酮（4），以及10-E-3，T形加合物2的晶体结构。 Br-2（12），3Br（2）（13）和4。 Br-2（14）。在MeCN中对1-4和Br-2之间的反应进行电导和分光光度研究，可以推测与形成分离的10-E-3（E = S，Se）高价化合物有关的平衡。为了理解S和Se供体在Br-2和I-2处理中提供不同产品类型的原因，已对1-8、19和20及其相应的假设[LEX]进行了DFT计算。 （+）阳离子（L =有机骨架; E = S，Se; X = Br，I），被认为是形成不同产物的关键中间体。根据NLEX在[LEX]（+）物种上的电荷分布获得的结果很好地解释了1-8、19和20在它们与Br-2和I-2反应中的不同行为。 X射线衍射研究表明12-14具有T形（10-E-3; E = S，Se）高价硫属元素。它们包含几乎垂直于有机分子平均平面的几乎线性的Br-E-Br（E = S，Se）系统。在12中，每个加合物分子的Se原子与相邻单元的Br（1）原子具有短相互作用，使得Se原子显示出大致正方形的平面配位。 Se-Br距离是不对称的[2.529（1）vs. 2.605（1）埃]。较短的距离是与短分子间接触所涉及的Br（1）原子的距离。相反，在位于两倍结晶轴上的分子加合物13和14中，Br-E-Br体系是对称的，没有观察到涉及硫族元素和溴原子的短分子间相互作用。加合物排列在平行的平面上。这导致了类似石墨的堆叠。从乙腈溶液中获得的10的新晶体修饰证实了分子间短接触在确定高价10-E-3中Br-E-Br（E = S，Se）和I-Se-I基团的不对称性中的重要性化合物。 Br-2与1和2-4的电导和分光光度滴定的相似性，以及11-14的振动光谱的相似性，也暗示了11的T形性质。Br-E的振动特性-Br（E = S，Se）系统类似于Br-3（-）和IBr2-阴离子：对称Br-E-Br基团的拉曼光谱仅在160 cm（-1）附近显示一个峰，因为可以发现对称的Br-3（-）和IBr2-阴离子，而不对称的Br-E-Br基团在190 cm（-1）附近也显示出反对称的Br-E-Br模式，如不对称的Br-3（- ）和IBr2-离子。因此，简单的IR和拉曼测量提供了一个有用的工具，可用于区分对称和不对称的Br-E-Br基团，因此，当没有高质量的晶体时，就可以对这些高价硫属元素化合物的晶体堆积进行预测。 [参考：76]

著录项

相似文献

  • 外文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号