Siloles and germoles modified by partial hypercoordination through aminoxy substituents
作者:Udo Losehand、Norbert W. Mitzel
DOI:10.1039/a909547k
日期:——
1-Dimethylaminoxy-2,3,4,5-tetraphenyl-1-silacyclopentadiene (1), 1,2-bis(dimethylaminoxy)-2,3,4,5-tetraphenyl-1-silacyclopentadiene (2) and 1,2-bis(dimethylaminoxy)-2,3,4,5-tetraphenyl-1-germacyclopentadiene (3) have been prepared by the reactions of the corresponding chloro-2,3,4,5-tetraphenyl-1-(sila/germa)cyclopentadienes with LiONMe2. They are yellow crystalline materials, which have been identified by multinuclear NMR spectroscopy (1H, 13C, 15N, 17O, 29Si), mass spectrometry and elemental analysis. The UV–VIS spectra of 1, 2 and 3 show the absorption bands of the silole/germole to be only slightly affected by the Si⋯N interaction, which indicates that orbital interactions of the type lp(N)→σ*(SiC) do not play a significant role and thus the Si⋯N attraction is better interpreted as a dipole interaction. The crystal structures of 2 and 3 reveal planar C4Si and C4Ge rings, with a propeller-like arrangement of the phenyl groups. The SiON and GeON groups contain short Si⋯N distances [2.473(3) and 2.503(3) Å in 2, and 2.535(7) to 2.608(7) Å in 3]. 2 adopts a gauche-gauche conformation for the NOSiON backbone, while in 3, two independent molecules are found in the asymmetric unit, one with an anti-gauche conformation and one with a gauche-gauche conformation.
1-二甲基氨基氧基-2,3,4,5-四苯基-1-硅杂环戊二烯(1)、1,2-双(二甲基氨基氧基)-2,3,4,5-四苯基-1-硅杂环戊二烯(2)和 1,2-双(二甲基氨基氧基)-2,3、和 1,2-双(二甲基氨基氧基)-2,3,4,5-四苯基-1-锗环戊二烯(3)是通过相应的氯-2,3,4,5-四苯基-1-(硅/锗)环戊二烯与 LiONMe2 反应制备的。它们是黄色晶体物质,已通过多核核磁共振光谱(1H、13C、15N、17O、29Si)、质谱和元素分析进行了鉴定。1、2 和 3 的紫外-可见光谱显示,硅极/锗极的吸收带只受到 Si⋯N 相互作用的轻微影响,这表明 lp(N)→σ*(SiC) 类型的轨道相互作用没有发挥重要作用,因此 Si⋯N 的吸引力最好被解释为偶极相互作用。2 和 3 的晶体结构显示出平面的 C4Si 和 C4Ge 环,苯基呈螺旋桨状排列。SiON 和 GeON 基团的 Si⋯N 间距很短 [2 中为 2.473(3) Å 和 2.503(3) Å,3 中为 2.535(7) Å 至 2.608(7) Å]。在 2 中,NOSiON 主干采用了高切-高切构象,而在 3 中,不对称单元中有两个独立的分子,一个具有反高切构象,另一个具有高切-高切构象。