Combination of the dithiol N,N'-bis(2-mercaptoethyl)isophthalamide, abbreviated as BDTH2 and as 1, with excess H2SeO3 in aqueous acidic (pH ≈ 1) conditions resulted in precipitation of BDT(S-Se-S) (6), with a (77)Se NMR chemical shift of δ = 675 ppm, and oxidized BDT. When the reaction is conducted under basic conditions Se(IV) is reduced to red Se(0) and oxidized 1. No reaction takes place between 1 and selenate (Se(VI)) under acidic or basic conditions. Compound 6 is stable in air but decomposes to red Se(0) and the disulfide BDT(S-S) (9) with heating and in basic solutions. Mechanisms and energetics of the reactions leading to 6 in aqueous solution were unraveled by extensive calculations at the ωB97X-D/aug-cc-pVTZ-PP level of theory. NMR chemical shift calculations with the gauge-independent atomic orbital (GIAO) method for dimethyl sulfoxide as solvent confirm the generation of 6 (calculated δ value = 677 ppm). These results define the conditions and limitations of using 1 for the removal of selenite from wastewaters. Compound 6 is a rare example of a bidentate selenium dithiolate and provides insight into biological selenium toxicity.
Three salen aluminum bromide compounds salen( t Bu)AlBr (1) (salen = N,N′-ethylenebis(3,5-di-tertbutylsalicylideneimine)), salpen( t Bu)AlBr (2) (salpen = N,N′-propylenebis(3,5-di-tert-butylsalicylideneimine)), and salophen( t Bu)-AlBr (3) (salophen = N,N′-o-phenylenenebis(3,5-di-tert-butylsalicylideneimine) were evaluated for their potential use as dealkylation agents with a series of organophosphates. These reactions led to the aluminum phosphate compounds containing six-coordinate aluminum centers and hydrolytically stable P−O−C bonds:] 2 , 9 = (salen( t Bu)AlO) 3 PO, 10 = (salpen( t Bu)AlO) 3 PO, 11 = (salophen( t Bu)AlO) 3 PO. All the compounds were characterized by 1 H, 13 C, 27 Al, and 31 P NMR, IR, and mass spectrometry. Furthermore, compounds 4−8 were structurally characterized by single-crystal X-ray diffraction. The potential hydrolysis of these compounds was modeled with 4 and demonstrated the unique stability of the final product and ease of isolation.
Rare earth metal‐organic frameworks generally contain lanthanide Ln 3+ ions coordinated by organic linkers with “hard” Lewis bases forming highly crystalline porous polymers. This chapter provides a brief description of rare earth metal‐organic frameworks and provides a comparison of their chemical and physical properties. The unique luminescent properties are examined across the lanthanide series and the origin of luminescence in rare earth metal‐organic frameworks is explored in detail. Potential applications involving rare earth metal‐organic frameworks are discussed. This includes their use as chemical sensors for various ions, small molecules, and changes in temperature. Additionally, their utility as potential materials for novel biotechnology applications is highlighted.
Rare earth oxides, which generally take the form Ln 2 O 3, are widely used in heterogeneous catalysis. This article provides a brief description of the Ln 2 O 3 oxides, which includes a comparison of their chemical and physical properties. The basicity of heterogeneous oxides is examined, and the different pKa's on the surface are modeled. The catalytic properties of the oxides will be correlated with their various chemical and physical properties. Several different examples of their use in rare earth heterogeneous catalysis will be described including oxidative methane coupling and transesterification of triglycerides.
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