270578-35-3Relevant articles and documents
Reactivity of a Nickel(II) Bis(amidate) Complex with meta-Chloroperbenzoic Acid: Formation of a Potent Oxidizing Species
Corona, Teresa,Pfaff, Florian F.,Acu?a-Parés, Ferran,Draksharapu, Apparao,Whiteoak, Christopher J.,Martin-Diaconescu, Vlad,Lloret-Fillol, Julio,Browne, Wesley R.,Ray, Kallol,Company, Anna
, p. 15029 - 15038 (2015)
Herein, we report the formation of a highly reactive nickel-oxygen species that has been trapped following reaction of a NiII precursor bearing a macrocyclic bis(amidate) ligand with meta-chloroperbenzoic acid (HmCPBA). This compound is only detectable at temperatures below 250 K and is much more reactive toward organic substrates (i.e., CH bonds, CC bonds, and sulfides) than previously reported well-defined nickel-oxygen species. Remarkably, this species is formed by heterolytic OO bond cleavage of a Ni-HmCPBA precursor, which is concluded from experimental and computational data. On the basis of spectroscopy and DFT calculations, this reactive species is proposed to be a NiIII-oxyl compound. A highly reactive nickel-oxygen species has been spectroscopically trapped after heterolytic OO bond cleavage during the reaction of a NiII precursor with meta-chloroperbenzoic acid (HmCPBA). This species is used to carry out the oxidation of different substrates, such as olefins, sulfides, and CH bonds (see scheme).
Synthesis of four derivatives of 3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid, the stabilities of their complexes with Ca(II), Cu(II), Zn(II) and lanthanide(III) and water-exchange investigations of Gd(III) chelates
Cheng, Tsan-Hwang,Wang, Yun-Ming,Lin, Kuei-Tang,Liu, Gin-Chung
, p. 3357 - 3366 (2007/10/03)
The protonation constants of four poly(aminocarboxylates), N′-pyridylmethyl (TTDA-PY), N′-2-hydroxypropyl (TTDA-HP), N′-2-hydroxy-1-phenylethyl (TTDA-H1P) and N′-2-hydroxy-2-phenylethyl (TTDA-H2P) derivatives of TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid), and the stability constants of their complexes formed with Ca2+, Zn2+, Cu2+, La3+, Ce3+, Nd3+, Sm3+, Gd3+, Dy3+, Ho3+, Yb3+ and Lu3+ were determined by potentiometric methods at 25.0 ± 0.1 °C and 0.10 mol dm-3 ionic strength in Me4NNO3. The stability of the Gd(III) complexes follows the order TTDA-PY > TTDA-H2P ≈ TTDA-HP ≈ TTDA-H1P. The thermodynamic resistance of the gadolinium(III) complexes, at the plasma concentration used in clinical applications, towards demetallation in the presence of important components of blood plasma, such as Ca(II), Zn(II) and Cu(II), has been evaluated. The observed water proton relaxivity values of [Gd(TTDA-PY)]-, [Gd(TTDA-HP)]-, [Gd(TTDA-H1P)]- and [Gd(TTDA-H2P)]- became constant with respect to pH changes over the range of 4-10, 6-10, 6-10 and 6-10, respectively. 17O NMR shifts showed that the [Dy(TTDA-PY)]-, [Dy(TTDA-HP)]-, [Dy(TTDA-H1P)]- and [Dy(TTDA-H2P)]- complexes at pH 6.30 and 4.30 had 0.9 and 0.9; 2.2 and 3.4; 2.0 and 3.5; 1.8 and 3.0 inner-sphere water molecules, respectively. Water proton spin-lattice relaxation rates for gadolinium(III) complexes were also consistent with the number of inner-sphere water molecules. The EPR transverse electronic relaxation rate and 17O NMR transverse relaxation time were thoroughly investigated and the results obtained were compared with that previously reported for the other gadolinium(III) complex, [Gd(DTPA)(H2O)]2-. Short exchange lifetime values were obtained for the [Gd(TTDA)(H2O)]2-, [Gd(TTDA-PY)(H2O)]-, [Gd(TTDA-HP)(H2O)2]-, [Gd(TTDA-H1P)(H2O)2]- and [Gd(TTDA-H2P)(H2O)2]- complexes. Their water-exchange rates are about 24-45 times faster than that for the [Gd(DTPA)(H2O)]2- complex, which suggested that the longer backbone of the multidentate ligand may be pulled tightly into the first coordination sphere, resulting in high steric constraints at the water binding site.
