首页> 外文期刊>Polyhedron: The International Journal for Inorganic and Organometallic Chemistry >Ion-pair charge transfer complexes with intense near IR absorption: Syntheses, crystal structures, electronic spectra and DFT calculations
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Ion-pair charge transfer complexes with intense near IR absorption: Syntheses, crystal structures, electronic spectra and DFT calculations

机译:具有强烈的近红外吸收的离子对电荷转移配合物:合成,晶体结构,电子光谱和DFT计算

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摘要

Five ion-pair complexes, consisting of R-benzylidene-1-aminopyridinium derivatives and [Ni(mnt)(2)](2-) (R = p-nitro (1), p-methyl (2), p-bromo (3), p-chloro (4) and m-nitro (5); mnt(2-) = maleonitriledithiolate), were synthesized and structurally characterized. As for 1, it is interesting to observe a large deviation from square-planar coordination geometry for the Ni atom, while no deviation is observed in the other four complexes. In the solid state, UV-Vis-NIR spectra of 2-5 show similar properties with intense absorption in the 200-750 nm and moderate near IR absorption in the 750-1000 nm region, whereas 1 exhibits an intense absorption from UV/Visible to near-IR region (200-1100 nm). This unique spectral feature of 1 is attributed to its distinctive structural differences from 2 to 5, namely the strong intermolecular packing interactions between anions and cations, as well as a significant deviation from the planarity of the anion. Based on DFT and TDDFT calculations, near-IR absorbance bands in 1-5 were assigned to combined transitions of d-d, MLCT and pi-pi* in the [Ni(mnt)(2)](2-) anion as well as the ion-pair charge transfer (IPCT) from the anionic HOMO to the cationic LUMO. The IPCT band position in acetonitrile is independent of the substituent group feature in benzene ring of cations for 1-5, which could be interpreted that the substituent group in benzene ring only has a minor contribution to the cationic LUMO. (C) 2008 Published by Elsevier Ltd.
机译:五个离子对络合物,由R-亚苄基-1-氨基吡啶鎓衍生物和[Ni(mnt)(2)](2-)组成(R =对硝基(1),对甲基(2),对溴(3)合成了对氯(4)和间硝基(5); mnt(2-)=顺丁烯二腈)。对于1,有趣的是观察到与Ni原子的方平面配位几何形状有很大偏差,而在其他四个配合物中则没有观察到偏差。在固态下,2-5的UV-Vis-NIR光谱显示出相似的特性,在200-750 nm处具有强烈的吸收,在750-1000 nm区域中具有中等的近红外吸收,而1在UV / Visible下显示出强烈的吸收到近红外区域(200-1100 nm)。 1的这种独特光谱特征归因于其从2到5的独特结构差异,即阴离子和阳离子之间的强分子间堆积相互作用以及与阴离子平面度的显着偏离。根据DFT和TDDFT计算,将[Ni(mnt)(2)](2-)阴离子中dd,MLCT和pi-pi *的组合跃迁指定为1-5中的近红外吸收带。从阴离子HOMO到阳离子LUMO的离子对电荷转移(IPCT)。乙腈中的IPCT能带位置与1-5个阳离子的苯环中的取代基基团特征无关,这可以解释为苯环中的取代基对阳离子LUMO的贡献很小。 (C)2008由Elsevier Ltd.发布

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