1,3,2-Dithiaphospholanes with an annelated 1,2-dicarba-closo-dodecaborane(12) unit: formation and reactivity
作者:Bernd Wrackmeyer、Elena V. Klimkina、Wolfgang Milius
DOI:10.1039/c3dt52753k
日期:——
1,3,2-Dithiaphospholanes were prepared, containing an annelated 1,2-dicarba-closo-dodecaborane(12) unit, bearing halogens (F, Cl, Br, and I), H, NEt2, OEt groups, or organo substituents (R = i-Pr, t-Bu, Cy, 3,5-Me2-C6H3-CH2, Ph) at phosphorus. The t-Bu derivative was structurally characterised as its sulfide. The organo-substituted derivatives escape the ring strain by irreversible (R = t-Bu; X-ray analysis) or reversible dimerisation, by which 10-membered rings are formed. Using 1,1-bis(dichlorophosphino)methane, another dimer containing a 14-membered ring could be isolated and structurally characterised. The preferred conformation of the 1,3,2-dithiaphospholanes depends on the nature of the substituent at phosphorus. For instance, the substituents R = t-Bu, NEt2 prefer the equatorial position, as indicated by diagnostic NMR data, supported by DFT calculations [B3LYP/6-311+G(d,p) level of theory]. The calculations also predict the tendency for dimerisation, and calculated NMR parameters are in good agreement, in most cases, with experimental data.
1,3,2-二硫代磷杂环烯被制备,含有一个环状的1,2-二碳-closo-十二硼烷(12)单元,磷原子上带有卤素(F、Cl、Br和I)、H、NEt2、OEt基团或有机取代基(R = i-Pr、t-Bu、Cy、3,5-Me2-C6H3-CH2、Ph)。t-Bu衍生物被结构表征为其硫化物。有机取代衍生物通过不可逆(R = t-Bu;X射线分析)或可逆二聚反应逃避了环张力,从而形成10个成员的环。使用1,1-二氯磷酸基甲烷,还可以分离和结构表征另一个包含14个成员环的二聚体。1,3,2-二硫代磷杂环烯的优选构象取决于磷原子上的取代基性质。例如,取代基R = t-Bu、NEt2更倾向于赤道位置,这通过诊断性NMR数据表明,并得到了DFT计算的支持[B3LYP/6-311+G(d,p)理论水平]。计算还预测了二聚的倾向,并且计算得到的NMR参数在大多数情况下与实验数据良好一致。