[1ChCl∶2EG]/CrCl_3·6H_2O离子液体中Cr(Ⅲ)配合物的研究

The Coordination Complexes of Cr(Ⅲ)in [1ChCl∶2EG]/CrCl_3·6H_2O ILs

利用电喷雾质谱(ESI-MS)和紫外-可见吸收光谱(UV-Vis)分析,研究了CrCl_3·6H_2O浓度为0.1~0.6mol·L^(-1)的水溶液和[1ChCl∶2EG]/CrCl_3·6H_2O ILs中,Cr(Ⅲ)配合物的存在形式。研究结果表明,在含有CrCl_3·6H_2O的溶液中,Cr(Ⅲ)与Cl^-和H_2O形成[Cr(H_2O)_nCl_(6-n)]^(n-3)配合物,其配合物的优势物种受CrCl_3·6H_2O浓度的影响。水溶液中Cr(Ⅲ)的优势配合物为[Cr(H_2O)_6]^(3+)与[Cr(H_2O)_5Cl]^(2+),并随CrCl_3·6H_2O浓度增加,水溶液的UV-Vis吸收光谱峰红移,[Cr(H_2O)_5Cl]^(2+)的相对含量增加。而[1ChCl∶2EG]/CrCl_3·6H_2O ILs中的优势配合物为[Cr(H_2O)_2Cl_4]^-和[Cr(H_2O)_3Cl_3],且随CrCl_3·6H_2O浓度增加,溶液的颜色从浅橙红色逐渐变为深绿色,溶液的UV-Vis吸收光谱峰蓝移,[Cr(H_2O)_3Cl_3]的相对量增加。说明CrCl_3·6H_2O的浓度变化,将影响配体Cl^-和H_2O与Cr(Ⅲ)配位结合的配位数,从而影响配合物优势物种的相对量。

The existing forms of Cr(Ⅲ)complexes in aqueous solution and[1ChCl∶2EG]/CrCl 3·6H 2O ILs containing 0.1~0.6 mol·L-1 CrCl 3·6H 2O,respectively,were investigated by using ESI-MS and UV-Vis absorption spectra.The results showed that Cr(Ⅲ)combined with Cl-and H 2O to form[Cr(H 2O)nCl 6-n]n-3 in both cases,and the dominant species of which were affected by the concentration of CrCl 3·6H 2O.Concretely,the dominant complexes of Cr(Ⅲ)in aqueous solution are[Cr(H 2O)6]3+and[Cr(H 2O)5Cl]2+,and the UV-Vis absorption spectra is observed to redshift with an increase in the concentration of CrCl 3·6H 2O,along with enhancement in the mole fraction of[Cr(H 2O)5Cl]2+.By contrast,thedominant species of Cr(Ⅲ)in[1ChCl∶2EG]/CrCl 3·6H 2O ILs are[Cr(H 2O)2Cl 4]-and[Cr(H 2O)3Cl 3].Increasing the concentration of CrCl3·6H 2O results in gradual color change of the solution from light orange-red to dark green,blue shift of the UV-Vis absorption spectra,and higher mole fraction of[Cr(H 2O)3Cl 3].Both the coordination number of Cl-and H 2O that complexes with Cr(Ⅲ)as well as the relative content of the dominant complexes of Cr(Ⅲ)in solvent is proved to be influenced by variation in theconcentration of CrCl 3·6H 2O.