Synthesis and Structure of Di-n-Butyltin Pyridine-2-phosphonate-6-carboxylate
摘要:
The crystal structure of di-n-butyltin pyridine-2-phosphonate-6-carboxylate, [C14H24NO6PSn](2), features centrosymmetric dimers disposed about a central Sn2O2 core. The phosphonate carboxylate dianion is mu(2)-tetradentate, coordinating one tin atom via one of the phosphonate oxygen atoms, the pyridine nitrogen atom, and one of the carboxylate oxygen atoms; the latter atom also coordinates the second tin atom of the dimer. The remaining positions in the seven-coordinate, distorted pentagonal bipyramidal geometry are occupied by a water molecule and two n-butyl groups that occupy axial positions. The lattice is stabilized by hydrogen-bonding contacts leading to an arrangement of parallel, orthogonally related chains of dimeric units. In methanol solution, the dimer is involved in a dissociation equilibrium that is fast on the NMR time scale.
作者:Zofia A. Dziuganowska、Katarzyna Ślepokura、Jean-Noël Volle、David Virieux、Jean-Luc Pirat、Paweł Kafarski
DOI:10.1021/acs.joc.6b00220
日期:2016.6.17
A small library of phosphonopiperidylcarboxylic acids, analogues of NMDA antagonist selfotel (CGS 19755), was synthesized. First, the series of aromatic esters was obtained via a palladium-catalyzed cross-coupling reaction (Hirao coupling) of dialkyl phosphites with bromopyridinecarboxylates, followed by their hydrolysis. Then, hydrogenation of the resulting phosphonopyridylcarboxylic acids over PtO2
Syntheses and Fe(II)/Fe(III) equilibria of the new multidentate ligands pyridine-2-phosphonic- 6-carbo×ylic acid and 2,6-pyridinediphosphonic acid for the use of their iron chelates as catalysts for the o×idation of H<sub>2</sub>S to S<sub>8</sub> by air
作者:Dian Chen、Arthur E. Martell、Ramunas J. Motekaitis、Derek McManus
DOI:10.1139/cjc-76-4-445
日期:——
The syntheses of two terdentate chelating agents, pyridine-2-phosphonic-6-carboxylic acid (2PP6C) and 2,6-pyridinediphosphonic acid (2,6PDPA), are described. The stepwise stability constants for the ferric complexes at 25.0 degrees C and mu=,0.100 M (KNO3) are log K-ML = 15.97 and log K-ML2 = 9.50 for 2PP6C, and log K-ML = 20.87 and log K(ML)2 = 7.81 for 2,6PDPA. Under the same conditions the stepwise formation constants for the ferrous chelates are log K-ML = 8.70 and log K-ML2 = 5.10 for 2PP6C, and log K-ML = 10.12 and log K-ML2 = 5.33 for 2,6PDPA. The stabilities of the Fe(III) and Fe(II) chelates are high enough to prevent precipitation of Fe(OH)(3) and FeS, respectively, from solutions having pH as high as 10.0. The rates of oxidative degradation of these ligands are very slow when the iron chelates are used as redox catalysts for the oxidation of H2S to S-8 by air. The rates of oxidative degradation are immeasurably slow when the iron chelates are used with sodium thiosulfate as a radical scavenger.
Pyridine-2-phospho-carboxylic Acids: Synthesis and Properties
作者:Bogdan Boduszek
DOI:10.1002/prac.19923340515
日期:——
6-Phosphoryl Picolinic Acids as Europium and Terbium Sensitizers
作者:Julien Andres、Anne-Sophie Chauvin
DOI:10.1021/ic200983y
日期:2011.10.17
Three 6-phosphoryl picolinic acid (6PPA) derivatives were synthesized and used as europium and terbium sensitizers. Two of the three ligands (6-diethoxyphosphoryl picolinic acid (Hdeppa) and 6-monoethoxyphosphoryl picofinic acid (H(2)meppa)) are water-soluble, once complexed to lanthanide ions, while the third (6-dihydroxyphosphoryl picolinic acid (H(3)dhppa)) forms a precipitate. The stability constants of the phosphoryl-based complexes were found to be higher than the carboxylate analogue (dipicolinic acid, H(2)dpa). The main species are the [LnL(3)] complexes under strict stoichiometric conditions, confirmed by (31)P NMR spectroscopy, mass spectrometry and lifetime analyses. The photophysical measurements reveal that the emission intensity of [Eu(deppa)(3)] is maximal at pH 4.8, whereas for [Eu(meppa)(3)](3-), the optimum pH is observed at 9.0. The lifetimes are all in the millisecond range and have confirmed the absence of water molecules in the first coordination sphere. The emissions of the terbium are always brighter than the corresponding europium within this phosphoryl series. The quantum yields of the phosphoryl containing complexes are lower than the carboxylate analogue ([Ln(dpa)(3)](3-)), except for [Tb(deppa)(3)], which exhibits an interesting quantum yield of 40% in aqueous solution.