[P(μ-NTer)]2: A Biradicaloid That Is Stable at High Temperature
[P(μ-NTer)]2: A Biradicaloid That Is Stable at High Temperature
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DOI：
10.1002/anie.201103742
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发表时间：
2011-01-01
影响因子：
16.6
通讯作者：
Villinger, Alexander
中科院分区：
文献类型：
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作者：
Beweries, Torsten;Kuzora, Rene;Villinger, Alexander
早在1894年，Michaelis和Schroeter就从苯胺盐酸盐与过量PCl 3的反应中分离出了第一个磷（III）-氮杂环（方案1）。[1]有趣的是，作者们假设已经分离出了单体物质，C6 H5 N = P2Cl，他们称之为“氯化磷偶氮苯”，但已经推测了二聚体的存在。今天我们知道二聚体是稳定的形式，这种[XP（μ-NR）] 2型的四元环，含有交替的磷（III）和氮中心，被称为环-1，3-二磷杂（III）-2，4-二氮烷（X=卤素，R=有机基团;旧名：1，3-二氮杂-2，4-二磷杂环丁烷）。[2]它们在制备磷-氮化学中起着重要作用，因为这些物种是多环无机和有机金属化合物的良好起始材料。[3，4]环-1，3-二磷杂（III）-2，4-二氮烷（1）可作为具有三角锥P和三角平面N原子的顺式或反式异构体存在。[3]N和P原子都有一个局域孤对电子。因此，对于这种类型的富电子杂环，形式上发现八个电子（方案2）。据我们所知，带有6 π电子的四元P2 N2环是未知的。如方案2所示，可以考虑三种可能的目标分子（2，3和4），其电子结构与芳烃（[4 n + 2] π电子）[5]相关。最有希望的合成候选物似乎是中性环-1，3-二氧杂环己烷。
As early as 1894 Michaelis and Schroeter isolated the first phosphorus (III)–nitrogen heterocycle from the reaction of aniline hydrochloride with an excess of PCl3 (Scheme 1).[1] Interestingly, the authors assumed to have isolated the monomeric species, C6H5ÀN= PÀCl, which they called “phosphazobenzene chloride” but already speculated on the existence of the dimer. Today we know that the dimer is the stable form, and such four-membered rings of the type [XP (μ-NR)] 2, which contain alternating phosphorus (III) and nitrogen centers, are called cyclo-1, 3-diphospha (III)-2, 4-diazanes (X= halogen, R= organic group; old name: 1, 3-diaza-2, 4-diphosphetidines).[2] They play a major role in preparative phosphorus–nitrogen chemistry because such species are good starting materials for polycyclic inorganic and organometallic compounds.[3, 4]Cyclo-1, 3-diphospha (III)-2, 4-diazanes (1) can exist as cis or trans isomers with trigonal-pyramidal P and trigonal-planar N atoms.[3] Both the N and the P atoms have one localized lone pair. Thus, formally eight electrons are found for this type of electron-rich heterocycles (Scheme 2). To the best of our knowledge, four-membered P2N2 rings bearing 6 π electrons are unknown. As illustrated in Scheme 2, three possible target molecules (2, 3, and 4) with electronic structures that are related to those of aromatic hydrocarbons ([4n+ 2] π electrons),[5] can be considered. The most promising candidate for synthesis seemed to be the neutral cyclo-1, 3-