首页> 外文期刊>Chemistry: A European journal >Redox non-innocence of thioether crowns: Spectroelectrochemistry and electronic structure of formal nickel(III) complexes of aza-thioether macrocycles
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Redox non-innocence of thioether crowns: Spectroelectrochemistry and electronic structure of formal nickel(III) complexes of aza-thioether macrocycles

机译:硫醚冠的氧化还原无毒:氮杂硫醚大环形式镍(III)配合物的光谱电化学和电子结构

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摘要

The Ni~(II) complexes [Ni([9]aneNS_2-CH_3) _2]~(2+) ([9]aneNS_2-CH_3=N-methyl-1-aza- 4,7-dithiacyclononane), [Ni(bis[9]aneNS_2-C_2H _4)]~(2+) (bis[9]aneNS_2-C_2H _4=1,2-bis-(1-aza-4,7-dithiacyclononylethane) and [Ni([9]aneS _3)_2]~(2+) ([9]aneS_3=1,4,7- trithiacyclononane) have been prepared and can be electrochemically and chemically oxidized to give the formal Ni~(III) products, which have been characterized by X-ray crystallography, UV/Vis and multi-frequency EPR spectroscopy. The single-crystal X-ray structure of [Ni~(III)([9] aneNS_2-CH_3)_2](ClO_4) _6·(H_5O_2)_3 reveals an octahedral co-ordination at the Ni centre, while the crystal structure of [Ni~(III)(bis[9]aneNS_2-C_2H_4)](ClO _4)_6·(H_3O)_3· 3H _2O exhibits a more distorted co-ordination. In the homoleptic analogue, [Ni~(III)([9]aneS_3)_2](ClO _4)_3, structurally characterized at 30 K, the Nii-S distances [2.249(6), 2.251(5) and 2.437(2) ?] are consistent with a Jahn-Teller distorted octahedral stereochemistry. [Ni([9]aneNS _2-CH_3)_2](PF_6)_2 shows a one-electron oxidation process in MeCN (0.2 M NBu_4PF_6, 293 K) at E_(1/2)=+1.10 V versus Fc~+/Fc assigned to a formal Ni~(III)/Ni~(II) couple. [Ni(bis[9]aneNS_2-C _2H_4)](PF_6)_2 exhibits a one-electron oxidation process at E_(1/2)=+0.98 V and a reduction process at E _(1/2)=-1.25 V assigned to Ni~(II)/Ni~(III) and Ni ~(II)/Ni~I couples, respectively. The multi-frequency X-, L-, S-, K-band EPR spectra of the 3+ cations and their 86.2 % ~(61)Ni- enriched analogues were simulated. Treatment of the spin Hamiltonian parameters by perturbation theory reveals that the SOMO has 50.6 %, 42.8 % and 37.2 % Ni character in [Ni([9]aneNS_2-CH_3)_2]~(3+), [Ni(bis[9]aneNS_2-C_2H_4)]~(3+) and [Ni([9]aneS_3)_2]~(3+), respectively, consistent with DFT calculations, and reflecting delocalisation of charge onto the S-thioether centres. EPR spectra for [~(61)Ni([9]aneS_3) _2]~(3+) are consistent with a dynamic Jahn-Teller distortion in this compound.
机译:Ni〜(II)配合物[Ni([9] aneNS_2-CH_3)_2]〜(2+)([9] aneNS_2-CH_3 = N-甲基-1-氮杂-4,7-二硫代环壬烷),[Ni(双[9] aneNS_2-C_2H _4)]〜(2+)(双[9] aneNS_2-C_2H _4 = 1,2-双-(1-氮杂-4,7-二硫代环壬基乙烷)和[Ni([9] aneS制备了_3)_2]〜(2+)([9] aneS_3 = 1,4,7-三硫代环壬烷),并可以进行电化学和化学氧化,得到形式为Ni〜(III)的产物,其特征在于X射线晶体学,UV / Vis和多频EPR光谱[Ni〜(III)([9] aneNS_2-CH_3)_2](ClO_4)_6·(H_5O_2)_3的单晶X射线结构揭示了Ni中心的八面体配位,而[Ni〜(III)(bis [9] aneNS_2-C_2H_4)](ClO _4)_6·(H_3O)_3·3H _2O的晶体结构表现出更扭曲的配位。在均质类似物中,[Ni〜(III)([9] aneS_3)_2](ClO_4)_3在结构上以30 K为特征,Nii-S距离为[2.249(6),2.251(5)和2.437( 2)?]与Jahn-Teller扭曲的八面体立体化学是一致的[Ni([9] aneNS _2-CH_3)_2](PF_6)_2显示了在MeCN(0.2 M NBu_4PF_6,293 K)中,E_(1/2)= + 1.10 V时的单电子氧化过程,相对于分配给正式Ni〜的Fc〜+ / Fc (III)/ Ni〜(II)对[Ni(bis [9] aneNS_2-C _2H_4)](PF_6)_2在E_(1/2)= + 0.98 V时显示单电子氧化过程,在E _(1/2)=-1.25时显示还原过程V分别分配给Ni〜(II)/ Ni〜(III)和Ni〜(II)/ Ni〜I对。模拟了3+阳离子及其富86.2%〜(61)Ni的类似物的多频X,L,S,K波段EPR谱。用摄动理论处理自旋哈密顿量参数表明,SOMO在[Ni([9] aneNS_2-CH_3)_2]〜(3 +),[Ni(bis [9]]中具有50.6%,42.8%和37.2%的镍特征aneNS_2-C_2H_4)]〜(3+)和[Ni([9] aneS_3)_2]〜(3+),分别与DFT计算一致,反映了电荷在S-硫醚中心的离域化。 [〜(61)Ni([9] aneS_3)_2]〜(3+)的EPR光谱与该化合物的动态Jahn-Teller畸变一致。

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