Stereochemical non-rigidity of phosphoranyl radicals: relative ligand apicophilicities
作者:John W. Cooper、Maxwell J. Parrott、Brian P. Roberts
DOI:10.1039/p29770000730
日期:——
A series of phosphoranyl radicals, produced by addition of photochemically generated alkoxyl or benzoyloxyl radicals to substituted 1,3,2-dioxaphospholans, have been studied by e.s.r. spectroscopy. The spectra of certain of these radicals exhibit line-shape effects which are interpreted in terms of intramolecular ligand exchange at phosphorus. On the basis of deuterium labelling studies, two types
通过ESR光谱法研究了通过将光化学产生的烷氧基或苯甲酰氧基基团加到取代的1,3,2-二氧杂膦酸酯上而产生的一系列磷酰基基团。这些自由基中某些自由基的光谱表现出线形效应,这可以通过磷中的分子内配体交换来解释。根据氘标记研究,已确定了两种类型的顶-赤道配体交换,分别涉及环外或环内取代基的互换。由4,4-二甲基-1,3,2-二氧杂磷杂环戊烷衍生的光谱表明,存在两个等摩尔磷烷基的近似等摩尔混合物,其中的内环CH 2O组位于顶端或赤道。某些环状和无环磷烷基的esr光谱显示,一般而言,配体的亲嗜性以F–,Cl–,RC(O)O –> [省略的图形] –,OCN–> RO–,R 2 N的顺序降低> H–> H 3 C–,紧密平行的基团电负性。用于与赤道ħ心尖的交换和Me速率常数2 Ñ配体,repectively,在无环基团ħ 2(Me)中ṖOBu吨和(ME 2 N)2 ClṖOBu吨进行了估计。