Trivalent Actinide and Lanthanide Complexation of 5,6-Dialkyl-2,6-bis(1,2,4-triazin-3-yl)pyridine (RBTP; R = H, Me, Et) Derivatives: A Combined Experimental and First-Principles Study

详细信息    查看全文

• 作者：Arunasis Bhattacharyya ; Eunja Kim ; Philippe F. Weck ; Paul M. Forster ; Kenneth R. Czerwinski
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：January 18, 2013
• 年：2013
• 卷：52
• 期：2
• 页码：761-776
• 全文大小：934K
• 年卷期：v.52,no.2(January 18, 2013)
• ISSN：1520-510X

文摘

Complexations of lanthanide ions with 5,6-dialkyl-2,6-bis(1,2,4-triazin-3-yl)pyridine [RBTP; R = H (HBTP), methyl (MeBTP), ethyl (EtBTP)] derivatives have been studied in the acetonitrile medium by electrospray ionization mass spectrometry, time-resolved laser-induced fluorescence spectroscopy, and UV鈥搗is spectrophotometric titration. These studies were carried out in the absence and presence of a nitrate ion in order to understand the effect of the nitrate ion on their complexation behavior, particularly in the poor solvating acetonitrile medium where strong nitrate complexation of hard lanthanide ions is expected. Consistent results from all three techniques undoubtedly show the formation of lower stoichiometric complexes in the presence of excess nitrate ion. This kind of nitrate ion effect on the speciation of Ln³⁺ complexes of RBTP ligands has not so far been reported in the literature. Different Am³⁺ and Ln³⁺ complexes were observed with RBTP ligands in the presence of 0.01 M tetramethylammonium nitrate, and their stability constant values are determined using UV鈥搗is spectrophotometric titrations. The formation of higher stoichiometric complexes and higher stability constants for Am³⁺ compared to Ln³⁺ ions indicates the selectivity of these classes of ligands. A single-crystal X-ray diffraction (XRD) study of europium(III) complexes shows the formation of a dimeric complex with HBTP and a monomeric complex with EtBTP, whereas MeBTP forms both the dimeric and monomeric complexes. Density functional theory calculations confirm the findings from single-crystal XRD and also predict the structures of Eu³⁺ and Am³⁺ complexes observed experimentally.