3847-57-2Relevant articles and documents
Influence of axial ligands on diverse properties in three trinickel string complexes
Zhang, Jing,Zhu, Long-Guan
, p. 1071 - 1077 (2012)
Three new trinickel string complexes, [Ni3(dpa)4(3-nba) 2](1), [Ni3(dpa)4(4-nba)2]·(CH 3OH) (2), and [Ni3(dpa)4(3,5-dnba)2](3) where dpa- is the anion of 2,2-dipyridylamine, 3-nba- is 3-nitrobenzoate anion, 4-nba is 4-nitrobenzoate anion, and 3,5-dnba- is 3,5-dinitrobenzoate anion, were synthesized in good yield and characterized by X-ray crystallography, infrared spectra, elemental analysis, magnetic susceptibility, cyclic voltammogram (CV), UV-vis spectra, fluorescence spectra, and TG analysis. The magnetic susceptibilities suggested that the terminal Ni atoms in all three complexes are in high-spin state while the central Ni atom is in a low-spin state. The CVs of complexes 1-3 showed reversible one-electron redox waves at E1/2 = 1.1395 V for 1, 1.108 V for 2, and 1.109 V for 3 corresponding to Ni3 7+/Ni3 6+. The Ni-Ni distances in three complexes are somewhat different, indicating the axial nitrobenzoate ligands have significant effect on the structural assembly. Supplemental materials are available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.
Stabilities of trityl-protected substrates: The wide mechanistic spectrum of trityl ester hydrolyses
Horn, Markus,Mayr, Herbert
supporting information; experimental part, p. 7469 - 7477 (2010/09/11)
Ionization rates of para-substituted triphenylmethyl (trityl) acetates, benzoates, and para-nitrobenzoates have been determined in aqueous acetonitrile and aqueous acetone at 25 °C. Conventional and stoppedflow techniques have been used to evaluate rate constants ranging from 1.38 × 10-5 to 2.15 × 102S-1 by conductimetry and photospectrometry methods. The varying stabilities of the differently substituted tritylium ions account for a gradual change of reaction mechanism. Poorly stabilized carbocations are generated slowly by the ionization of their covalent precursors and trapped fast by water. Better stabilized carbocations are generated more rapidly and accumulate, so that ionization and trapping by water can be observed as separate steps in a single experiment. Finally, highly stabilized tritylium ions do not react with water, and only the rates of their formation could be measured. The ionization rate constants correlate linearly with Winstein's ionizing powers Y; the low slopes (0.17 + parameters is excellent for symmetrically substituted tritylium derivatives, deviations for unsymmetrically substituted systems are observed. The failing rate-equilibrium relationship between the rates of ionizations (log kion) and the stabilities of the carbocations in aqueous solution (pKR+) may be explained by the late " development of resonance between a p-amino group and the carbocationic center of the tritylium ion during the ionization process.
Effect of solvents on the kinetics and mechanism of the acidic and alkaline hydrolysis of hydroxamic acids
Ghosh, Kallol K.,Krishnani, Kishore K.,Ghosh, Sharmistha
, p. 337 - 342 (2007/10/03)
The acid catalyzed hydrolysis of N-phenylbenzohydroxamic acid (PBHA) C6H5C(=0)N(OH)C6H5 has been studied in aq. dioxane, acetone, dimethylsulphoxide, dimethylformamide, methanol, ethanol and 2-propanol mixtures. Dioxane and methanol have a rate enhancing effect but DMF, acetone, ethanol and 2-propanol exert a rate decreasing effect. In DMSO an increase is followed by a decrease i.e. a rate maximum is observed. An attempt has also been made to study the alkaline hydrolysis of PBHA and two of its derivatives (X-C6H4C(=0)N(OH)C6H5; X=4-NO2, 4-Cl) in aq. dioxane. In all case the pseudo first order rate constant increase with increasing dioxane content. The activation parameters ΔH(+), Δ(+), and ΔGH(+) have been calculated. An attempt has been made to correlate rate data for acidic hydrolysis in terms of solvatochromic parameters and linear free energy relationships.