A kinetically stabilized ferrocenyl diphosphene: Synthesis, structure, properties, and redox behavior
A kinetically stabilized ferrocenyl diphosphene: Synthesis, structure, properties, and redox behavior
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DOI：
10.1002/chem.200400577
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发表时间：
2004-12-03
影响因子：
4.3
通讯作者：
Tokitoh, N
中科院分区：
文献类型：
--
作者：
Nagahora, N;Sasamori, T;Tokitoh, N
以2，4，6-三[二(三甲基硅基)甲基]苯基[TBT-P(H)-P(Cl)-FC](8)为原料，通过脱氯化氢反应合成了一种新的稳定的二茂铁基二膦[TBT-P=P-FC](1)(TBT=2，4，6-三[双(三甲基硅基)甲基]苯基，Fe=二茂铁基)，1，8-二氮杂双环[5.4.0]在1，8-二氮杂环-7-烯(DBU)下以较高的产率合成。双膦1在固态和溶液中都非常稳定。在P-31核磁共振谱(CA)中，双膦I在501.7和479.5 ppm处呈现低场AB四重态，其耦合常数(1)J(PP)=546 Hz，这是不对称取代的反式双膦的特征。通过X-射线晶体分析确定了1的分子结构，其结构为反式双膦，其C-P-P-C扭转角为177.86(17)度。1[2.0285(15)埃]的P-P键长比典型的P-P单键长度(约2.22-2.24埃)短得多，在已报道的二芳基双膦的P=P双键长度(1.985-2.051埃)范围内，证明了固体中1的P=P双键特征。此外，1的循环伏安曲线在-1.95和+0.34V分别出现了可逆的还原和氧化对。1的电化学结果得到了密度泛函理论的合理支持，这表明LUMO和HOMO轨道应该分别是铁(II)原子的双膦部分的pi*轨道和d轨道。
A new, stable ferrocenyl diphosphene [Tbt-P=P-Fc] (1) (Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl, Fe = ferrocenyl) was synthesized by the dehydrochlorination reaction of the corresponding diphosphane, [Tbt-P(H)-P(Cl)-Fc] (8), with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in good yield. Diphosphene 1 is very stable in the solid state and also in solution. In the P-31 NMR spectrum (CA), diphosphene I showed a low-fielded AB quartet at delta 501.7 and 479.5 ppm with the coupling constant (1)J(PP) = 546 Hz, which is characteristic of an unsymmetrically substituted trans-diphosphene. The molecular structure of 1 was established by X-ray crystallographic analysis, which showed a trans-diphosphene with a C-P-P-C torsion angle of 177.86(17)degrees. The phosphorus-phosphorus bond length of 1 [2.0285(15) Angstrom] which is considerably shorter than the typical P-P single-bond lengths (ca. 2.22-2.24 Angstrom) and within the range of reported P=P double-bond lengths (1.985-2.051 Angstrom) for diaryl diphosphenes, evidenced the P=P double-bond character of 1 in the solid state. In addition, the cyclic voltammograms of 1 showed reversible reduction and oxidation couples at -1.95 and +0.34 V versus SCE, respectively. The electrochemical results for 1 were reasonably supported by the DFT calculations, which suggested that the LUMO and HOMO orbitals should be mainly pi* orbital of the diphosphene moiety and d orbitals of the iron(II) atom, respectively.