Kinetically Stabilized 1,1′-Bis[(<i>E</i>)-diphosphenyl]ferrocenes: Syntheses, Structures, Properties, and Reactivity
作者:Noriyoshi Nagahora、Takahiro Sasamori、Yasuaki Watanabe、Yukio Furukawa、Norihiro Tokitoh
DOI:10.1246/bcsj.80.1884
日期:2007.10.15
Kinetically stabilized 1,1′-bis[(E)-diphosphenyl]ferrocenes were synthesized by taking advantage of extremely bulky substituents, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (denoted as Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (denoted as Bbt) groups, and characterized by the spectroscopic and X-ray crystallographic analyses. The electronic structures of the 1,1′-bis[(E)-diphosphenyl]ferrocenes were determined by analyzing electronic spectra, the transitions of which were reasonably assigned based on theoretical calculations. In the cyclic voltammograms, there were two well-defined reversible one-electron reduction couples corresponding to the intramolecular two diphosphene units. Furthermore, the 1,1′-bis[(E)-diphosphenyl]ferrocene was found to undergo ligand-exchange reactions with group 6 metal carbonyl complexes along with the E-to-Z isomerization of the diphosphene moieties, leading to the formation of the corresponding 1,1′-bis[(Z)-diphosphenyl]ferrocene group 6 metal tetracarbonyl complexes, [M(CO)4(Z,Z)-(BbtP=PC5H4)2Fe}] (M=Cr, Mo, and W). The molecular structures of these complexes were determined by spectroscopic analyses (1H, 13C, and 31P NMR spectra, and UV–vis spectra), and that of the tungsten complex was determined by X-ray crystallographic analysis. Several types of d→π∗P=P electron transitions due to the iron and group 6 metals were detected by using UV–vis spectroscopy, and these results were supported by theoretical calculations.
通过利用极 bulky 取代基 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl(简称 Tbt)和 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl(简称 Bbt)合成了动力学稳定的 1,1′-双[(E)-二膦基]铁烯,并通过光谱学和 X 射线晶体学分析进行了表征。通过分析电子光谱确定了 1,1′-双[(E)-二膦基]铁烯的电子结构,过渡的合理归属基于理论计算。在循环伏安图中,观察到与分子内两个二膦单位对应的两个明确的可逆一电子还原对。此外,发现 1,1′-双[(E)-二膦基]铁烯与 6 族金属碳氧络合物发生配体交换反应,同时导致二膦基团的 E-Z 异构化,形成相应的 1,1′-双[(Z)-二膦基]铁烯 6 族金属四羧基络合物 [M(CO)4(Z,Z)-(BbtP=PC5H4)2Fe}](M=Cr、Mo 和 W)。这些络合物的分子结构通过光谱分析(1H、13C 和 31P NMR 光谱,以及 UV–vis 光谱)确定,其中钨络合物的结构则通过 X 射线晶体学分析确定。使用 UV–vis 光谱检测到了由于铁和 6 族金属引起的几种类型的 d→π∗ P=P 电子跃迁,且这些结果得到了理论计算的支持。