Phenalene−phosphazene complexes: injection of electron spin density into the cyclotriphosphazene ring system
Phenalene−phosphazene complexes: injection of electron spin density into the cyclotriphosphazene ring system
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苯酚-磷腈配合物：将电子自旋密度注入环三磷腈环系
DOI：
10.1021/ja00311a061
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发表时间：
1985
影响因子：
15
通讯作者：
J. H. Marshall
中科院分区：
文献类型：
--
作者：
R. Haddon;S. L. Mayo;S. V. Chichester;J. H. Marshall
提出了一种理论模型，该模型提供了一种通过磷 dT 轨道将电子自旋密度从螺取代基注入磷腈键的机制。这种 pT-dT 螺离域化对于为磷原子选择的 dT 基本集是不变的。 1, 9-二取代-苯烯基体系显示出具有满足理论模型要求的前沿分子轨道。一系列六氯环三磷腈的单取代螺[菲那烯]衍生物已被制备和表征。用三氟乙氧基取代剩余的氯官能团的尝试产生了不同的取代模式，具体取决于菲那烯部分的性质。 4,, 4', 6,, 6,-四（三氟乙氧基）-4,, 4', 6', 6,-四氢-l-甲基螺[phenaleno [l, 9-i/e]-l, 3, 2-二氮杂磷碱-2 (l//), 2'-[1, 3, 5, 2, 4, 6] 三氮杂三磷](8) 在三氟乙醇钠存在下保持其结构完整性，并且可以在没有并发症的情况下分离。该化合物在环外亚氨基氮原子上经历质子化和甲基化（产生 9+、BF4~）。后一个结果已通过 9+, BPh4" 的 X 射线晶体学研究得到证实。电子和 P31 NMR 谱提供的证据强烈表明，即使与阳离子取代基键合（如 9+ 中出现的那样），四（三氟乙氧基）环三磷腈系统也是强电子受体。8 和 9+, BF4" 均具有电活性，显示出 和两个还原步骤，分别。第一个还原产物已通过电子自旋共振光谱进行了检查。对 9 获得的 ESR 光谱的分析提供了电子自旋密度注入磷腈键片段的第一个证据。至少一半的环三磷腈环核具有 ESR 活性。近年来，磷腈的环状和线性（聚合）形式引起了人们的极大兴趣。 1-3 这些化合物的化学性质日益完善，磷腈可能构成无机同源共价化合物的首要例子。磷腈的结构和键合在环系中的成键、离域和芳香特征方面特别令人感兴趣，并且关于环磷腈和聚磷腈的电子结构存在许多重要的悬而未决的问题。在许多方面，磷腈的化学性质与共轭有机化合物的化学性质相似。然而，有一个重要的区别：虽然磷腈中的 PN 键通常长度相等，并且可能在形式上的单键和双键之间处于中间状态，但它们没有表现出通常与共轭有机物相关的许多特征。
A theoretical model is advanced which provides a mechanism for the injectionof-electron spin density from a spirosubstituent into a phosphazene linkage via the phosphorus dT orbitals. Such pT-dT spirodelocalization is shown to be invariant to the dT basic set chosen for the phosphorusatom. The 1, 9-disubstituted-phenalenyl system is shown to possess a frontier molecular orbital which fulfills the requirements of the theoretical model. A series of monosubstituted-spiro [phenalene] derivatives of hexachlorocyclotriphosphazene havebeen prepared and characterized. Attempts to replace the remaining chlorine functionality with trifluoroethoxy groups gave rise to different modes of substitution, depending on the nature of the phenalene moiety. 4,, 4', 6,, 6,-tetrakis (trifluoroethoxy)-4,, 4', 6', 6,-tetrahydro-l-methylspiro [phenaleno [l, 9-i/e]-l, 3, 2-diazaphosphorine-2 (l//), 2'-[1, 3, 5, 2, 4, 6] triazatriphosphorine](8) retains its structural integrity in the presence of sodium trifluoroethoxide and may be isolated without complications. The compound undergoes both protonation and methylation (to produce 9+, BF4~) on the exocyclic imino-nitrogen atom. This latter result has been confirmed by an X-ray crystallographic study of 9+, BPh4". Electronic and P31 NMR spectra provide evidence which strongly suggests that the tetrakis (trifluoroethoxy) cyclotriphosphazene system is a strong electron acceptor even when bonded to a cationic substituent (as occurs in 9+). Both 8 and 9+, BF4" are electroactive, showing one and two reduction steps, respectively. The first reduction products havebeen examinedby electron spin resonance spectroscopy. Analysis of the ESR spectrum obtained from 9 providesthe first evidence for the injection of electron spin density into a segment of a phosphazene linkage. At least half of the cyclotriphosphazene ring nuclei are ESR-active.The phosphazenes havebeen of great interest in recent years, both in their cyclic and linear (polymeric) forms. 1-3 The chemistry of these compounds is becomingincreasingly well-developed and the phosphazenes probably constitute the premiere example of an inorganic homologous covalent class of compounds. The structures and bonding of the phosphazenes are of particular interest with respect to-bonding, delocalization, and aromatic character in the ring systems, and there are a number of important outstanding questions with regard to theelectronic structure of the cyclo-and polyphosphazenes. In many respects, the chemistry of the phosphazenes parallels that of conjugated organiccompounds. There is, however, an important difference: while the PN bonds in phosphazenes are usually equal in length and presumably intermediate in character between formal single and double bonds, they do not show many of the characteristicsnormally associated with conjugated organic