Cadmium(II) complex formation with selenourea and thiourea in solution: an XAS and 113Cd NMR study.
Cadmium(II) complex formation with selenourea and thiourea in solution: an XAS and 113Cd NMR study.
复制标题
解决方案中的镉（II）与Selenourea和Thiourea的复合形成：XAS和113CD NMR研究。
DOI：
10.1021/ic300852t
复制
发表时间：
2012-10-15
影响因子：
4.6
通讯作者：
Parmar K
中科院分区：
文献类型：
--
作者：
Jalilehvand F;Amini Z;Parmar K
用~（113）Cd NMR和X射线吸收光谱研究了Cd（CF_3SO_3）_2在甲醇溶液中与硒代硫酸根（SeU）或硫脲（TU）以及硫脲在水溶液中形成的配合物。在低温（~200 K）下，观察到明显的113 Cd NMR信号，对应于配体缓慢交换的CdLn ~（2+）物种（n = 0 - 4，L = TU或SeU）。峰积分被用来获得在甲醇溶液中的形态，允许稳定性常数进行估计。在Cd（S/Se）O_5或Cd（S/Se）_2O_4（O来自MeOH或CF_3SO_3 ~-）环境中，含硒（C=S）或硒（C=Se）基团的镉（II）配合物的~（113）Cd化学位移非常相似，分别在93-97 ppm和189 - 193 ppm之间。然而，Cd（SeU）42+（578 pm）和Cd（TU）42+（526 ppm）物种的化学位移的差异，分别与CdSe 4和CdS 4配位，显示配位Se原子的化学屏蔽比S少，与按顺序增加屏蔽的共同趋势相反：O > N > Se >S。在溶液中占主导地位的单和四硫脲/硒络合物，它们的配位和键距可以评估镉K边扩展X射线吸收精细结构（EXAFS）光谱。在~200 K和高过量硫脲下，通过113 Cd NMR信号的高场位移（高达423 ppm）和EXAFS振荡的振幅降低，检测到少量（高达~30%）的[Cd（TU）5-6]2+物种。通过拟合[Cd（TU）4]2+和[Cd（TU）6]2+络合物的模拟EXAFS光谱的线性组合来估计量。在室温下，[Cd（TU）4]2+是形成的最高络合物，也在水溶液中。镉L3边X射线吸收近边结构（XANES）光谱的镉（II）硫脲在甲醇中的溶液中，用于跟踪在室温下的CdSxOy配位的变化。113镉NMR化学位移和不同的镉（II）的协调环境之间的当前和以前的研究中发现的相关性通常是有用的评估镉配位含硫或硒供体配体在生化系统中或监测溶液中的形态。
The complexes formed in methanol solutions of Cd(CF3SO3)2 with selenourea (SeU) or thiourea (TU), for thiourea also in aqueous solution, were studied by combining 113Cd NMR and X-ray absorption spectroscopy. At low temperature (~200 K) distinct 113Cd NMR signals were observed, corresponding to CdLn2+ species (n = 0 - 4, L = TU or SeU) in slow ligand exchange. Peak integrals were used to obtain the speciation in the methanol solutions, allowing stability constants to be estimated. For cadmium(II) complexes with thione (C=S) or selone (C=Se) groups coordinated in Cd(S/Se)O5 or Cd(S/Se)2O4 (O from MeOH or CF3SO3-) environments the 113Cd chemical shifts were quite similar, within 93-97 ppm and 189 – 193 ppm, respectively. However, the difference in the chemical shift for the Cd(SeU)42+ (578 pm) and Cd(TU)42+ (526 ppm) species, with CdSe4 and CdS4 coordination, respectively, shows less chemical shielding for the coordinated Se atoms than for S, in contrast to the common trend with increasing shielding in the order: O > N > Se >S. In solutions dominated by mono- and tetra-thiourea / selenourea complexes, their coordination and bond distances could be evaluated by Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy. At ~200 K and high excess of thiourea a minor amount (up to ~30%) of [Cd(TU)5-6]2+ species was detected by an upfield shift of the 113Cd NMR signal (up to 423 ppm) and an amplitude reduction of the EXAFS oscillation. The amount was estimated by fitting linear combinations of simulated EXAFS spectra for [Cd(TU)4]2+ and [Cd(TU)6]2+ complexes. At room temperature, [Cd(TU)4]2+ was the highest complex formed, also in aqueous solution. Cd L3-edge X-ray absorption near edge structure (XANES) spectra of cadmium(II) thiourea solutions in methanol were used to follow changes in the CdSxOy coordination at room temperature. The correlations found from the current and previous studies between 113Cd NMR chemical shifts and different Cd(II) coordination environments are generally useful for evaluating cadmium coordination to thione-containing or Se-donor ligands in biochemical systems or for monitoring speciation in solution.
登录
查看更多内容
DOI：
10.1039/dt9720002103
发表时间：
1972-01-01
期刊：
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
影响因子：
--
作者：
AITKEN, GB;MCQUILLAN, GP;DUNCAN, JL
通讯作者：
DUNCAN, JL
DOI：
10.1002/zaac.19936190426
发表时间：
1993-04-01
影响因子：
1.4
作者：
BENSCH, W;SCHUSTER, M
通讯作者：
SCHUSTER, M
影响因子：
4.6
作者：
BOND, AM;COLTON, R;ELLIS, SR
通讯作者：
ELLIS, SR
DOI：
10.1039/f19868203415
发表时间：
1986-01-01
期刊：
JOURNAL OF THE CHEMICAL SOCIETY-FARADAY TRANSACTIONS I
影响因子：
--
作者：
CROW, DR
通讯作者：
CROW, DR
影响因子：
3
作者：
Epifani, M;Giannini, C;Manna, L
通讯作者：
Manna, L