Synthesis, characterisation and reactions of bis[2-(dimethylaminomethyl)-phenyl] diselenide: its structure and that of [2-(dimethylaminomethyl)phenyl]-selenium bromide
作者:Rupinder Kaur、Harkesh B. Singh、Rajan P. Patel
DOI:10.1039/dt9960002719
日期:——
Bis[(2-dimethylaminomethyl)phenyl] diselenide (RSe)2 was obtained by the organolithium route. It underwent facile reaction with stoichiometric amounts of bromine and iodine to give the corresponding arylselenium halides RSeBr and novel RSeI in which the selenium is covalently bonded to iodine. With an excess of bromine it gave the corresponding tribromide RSeBr3 but a similar reaction with iodine gave only RSeI. With diazomethane it gave the selenoether (RSe)2CH2 and with HCl the known bis(hydrochloride)(RSe)2·2HCl. A catalytic conversion of alkenes into allylic acetates using (RSe)2 was carried out. The compounds were characterised by elemental analyses, mass, multinuclear NMR (1H, 13C, 77Se), IR, Fourier-transform-Raman spectrometry and conductance measurements. The compound RSeBr3 shows evidence for the existence of Se ⋯ N interaction in solution and was found to equilibrate between co-ordinated and non-co-ordinated forms. The structures of the diselenide (RSe)2 and its bromo derivative RSeBr were determined by X-ray crystallography. The compounds are isostructural and exhibit Se ⋯ N intramolecular co-ordination. The Se atom has T-shaped three-co-ordination in both structures and the five-membered chelate rings formed by the Se, C and N atoms are puckered and exist in an envelope conformation. The Se ⋯ N interaction in RSeBr [Se–N 2.143(6)Å] is, however, considerably stronger than that in (RSe)2[Se(1)–N(1) 2.856(3), Se(2)–N(2) 2.863(4)Å].
Bis[(2-二甲氨基甲基)苯基]二硒化物(RSe)₂是通过有机锂法获得的。它与等摩尔量的溴和碘发生了简单反应,生成相应的芳基硒卤化物RSeBr和新型RSeI,其中硒与碘形成共价键。在过量的溴存在下,生成了相应的三溴化物RSeBr₃,但与碘的类似反应仅生成了RSeI。与气态二氟甲烷反应产生了硒醚(RSe)₂CH₂,与HCl反应生成已知的双(盐酸盐)(RSe)₂·2HCl。使用(RSe)₂进行的催化反应将烯烃转化为烯丙基醋酸酯。该化合物通过元素分析、质谱、多核核磁共振(¹H, ¹³C, ⁷⁷Se)、红外光谱、傅里叶变换拉曼光谱和电导率测量进行了表征。化合物RSeBr₃在溶液中显示出Se⋯N相互作用的证据,并发现其在配位和非配位形式之间达到平衡。二硒化物(RSe)₂及其溴衍生物RSeBr的结构通过X射线晶体学确定。该化合物是同构结构,并表现出Se⋯N分子内配位。在两种结构中,Se原子具有T形三配位,而由Se、C和N原子形成的五元螯合环呈现鼓起的信封构象。然而,RSeBr中的Se⋯N相互作用[Se–N 2.143(6)Å]显著强于(RSe)₂中的相互作用[Se(1)–N(1) 2.856(3), Se(2)–N(2) 2.863(4)Å]。