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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Effect of intramolecular pi-pi and CH-pi interactions between ligands on structure, electrochemical and spectroscopic properties of fac-[Re(bpy)(CO)(3)(PR3)](+) (bpy=2,2 '-bipyridine; PR3 = trialkyl or triarylphosphines)
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Effect of intramolecular pi-pi and CH-pi interactions between ligands on structure, electrochemical and spectroscopic properties of fac-[Re(bpy)(CO)(3)(PR3)](+) (bpy=2,2 '-bipyridine; PR3 = trialkyl or triarylphosphines)

机译：配体之间的分子内pi-pi和CH-pi相互作用对fac- [Re（bpy）（CO）（3）（PR3）]（+）（bpy = 2,2'-联吡啶的结构，电化学和光谱性质的影响; PR3 =三烷基或三芳基膦）

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Intramolecular pi-pi and CH-pi interactions between the bpy and PR3 ligands of fac-[Re(bpy)(CO)(3)(PR3)](+) affect their structure, and electrochemical and spectroscopic properties. Intramolecular CH-pi interaction was observed between the alkyl groups on the phosphine ligand (R = Bu-n, Et) and the bpy ligand, and intramolecular pi-pi and CH-pi interactions were both observed between the aryl group(s) on the phosphorus ligand (R = p-MeOPh, p-MePh, Ph, p-FPh, OPh) and the bpy ligand, while no such interactions were found in the trialkylphosphite complexes (R = (OPr)-Pr-i, OEt, OMe). The intramolecular interactions distort the pyridine rings of the bpy ligand as long as 3.7 x 10(-2) Angstrom in crystals. Molecular orbital calculations of the bpy ligand suggest that this distortion decreases the energy gap between its pi and pi* orbitals. An absorption band attributed to the pi-pi* (bpy) transition of the distorted rhenium complexes, measured in a KBr pellet, was red-shifted by 1-5 nm compared to the complexes without the distorted bpy ligand. Even in solution, similar red shifts of the pi-pi* (bpy) absorption were observed. The redox potential E-1/2(bpy/bpy(.-)) of the complexes with the trialkylphosphine and triarylphosphine ligand are shifted positively by 110-120 mV and 60-80 mV respectively, compared with those derived from the electron-attracting property of the phosphorus ligand. In contrast with these properties, three nu(CO) IR bands, which are sensitive to the electron density on the central rhenium because of pi-back bonding, were shifted to higher energy, and a Re(I/II)-based oxidation wave was observed at a more positive potential according to the electron-attracting property of the phosphorus ligand.
机译：fac- [Re（bpy）（CO）（3）（PR3）]（+）的bpy和PR3配体之间的分子内pi-pi和CH-pi相互作用影响其结构以及电化学和光谱性质。在膦配体（R = Bu-n，Et）和bpy配体上的烷基之间观察到分子内CH-pi相互作用，并且在芳基上的芳基之间观察到分子内pi-pi和CH-pi相互作用。磷配体（R = p-MeOPh，p-MePh，Ph，p-FPh，OPh）和bpy配体，而在亚磷酸三烷基酯络合物中未发现此类相互作用（R =（OPr）-Pr-1，OEt， OMe）。分子内相互作用使bpy配体的吡啶环扭曲，直到晶体中的3.7 x 10（-2）埃。 bpy配体的分子轨道计算表明，这种扭曲减小了其pi和pi *轨道之间的能隙。与不含扭曲的bpy配体的复合物相比，在KBr颗粒中测量的归因于扭曲的complex配合物的pi-pi *（bpy）跃迁的吸收带被红移了1-5 nm。即使在溶液中，也观察到类似的pi-pi *（bpy）吸收红移。与三烷基膦和三芳基膦配体配合物的氧化还原电势E-1 / 2（bpy / bpy（.-））分别正向偏移110-120 mV和60-80 mV，与从电子吸引得到的相比磷配体的性质。与这些性质相比，由于π背键对中心上的电子密度敏感的三个nu（CO）IR波段被转移到更高的能量，并产生了基于Re（I / II）的氧化波根据磷配体的电子吸引特性，在更正的电势下观察到α。

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