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191.
A. M. George N. C. Mishra M. S. Nagar N. C. Jayadevan 《Journal of Thermal Analysis and Calorimetry》1996,47(6):1701-1708
Thermal decomposition of the amorphous coprecipitate of yttrium and aluminium hydroxides forming yttrium aluminium garnet has been investigated employing thermal analyses, X-ray diffraction and IR spectroscopy. On heating, the coprecipitate progressively loses water forming a stable but highly disordered hydroxy garnet which crystallizes at 1180 K and decomposes to YAG at 1290 K. Nucleation of the crystalline phase appears to begin at 800 K.The authors thank Dr. P. V. Ravindran of the Analytical Chemistry and Shri N. K. Kulkarni of the Fuel Chemistry Divisions of BARC for their assistance in the thermoanalytical experiments. 相似文献
192.
Xu-Fang Chen Li Liu Jian-Gong Ma Long Yi Peng Cheng Dai-Zheng Liao Shi-Ping Yan Zong-Hui Jiang 《Journal of Molecular Structure》2005,750(1-3):94-100
A series of chromium(III) complexes [Cr(bipy)(HC2O4)2]Cl·3H2O (1), [Cr(phen)(HC2O4)2]Cl·3H2O (2), [Cr(phen)2(C2O4)]ClO4 (3), [Cr2(bipy)4(C2O4)](SO4)·(bipy)0.5·H2O (4) and [Mn(phen)2(H2O)2]2[Cr(phen)(C2O4)2]3ClO4·14H2O (5) were synthesized (bipy=4,4′-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3–5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1–3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed. 相似文献
193.
194.
Synthesis and Structure of Ammine and Amido Complexes of Iridium The reaction of (NH4)2[IrCl6] with NH4Cl at 300 °C in a sealed glass ampoule yields the iridium(III) ammine complex (NH4)2[Ir(NH3)Cl5], which crystallizes isotypically with K2[Ir(NH3)Cl5] in the orthorhombic space group Pnma with Z = 4, and a = 1350.0(2); b = 1028.5(3); c = 689.6(2) pm. The reaction of (NH4)2[IrCl6] with NH3 at 300 °C, however, gives the already known [Ir(NH3)5Cl]Cl2 beside a small amount of [Ir(NH3)4Cl2]Cl2. In pure form [Ir(NH3)5Cl]Cl2 is obtained by ammonolysis of (NH4)2[Ir(NH3)Cl5] at 300 °C with NH3. [Ir(NH3)4Cl2]Cl2 crystallizes triclinic (P1, Z = 1, a = 660,2(3); b = 680,4(3); c = 711,1(2) pm; α = 103,85(2)°, β = 114,54(3)°, γ = 112,75(2)°). The structure contains Cl– anions and [Ir(NH3)4Cl2]2+ cations with a trans position of the Cl atoms. Upon reaction of [Ir(NH3)5Cl]Cl2 with Cl2 one ammine ligand is eliminated yielding [Ir(NH3)4Cl2]Cl, which is transformed to orthorhombic [Ir(NH3)4(OH2)Cl]Cl2 (Pnma, Z = 4, a = 1335,1(3); b = 1047,9(2); c = 673,4(2) pm) by crystallization from water. In the octahedral complex [Ir(NH3)4(OH2)Cl]2+ the four ammine ligands have an equatorial position, whereas the Cl atom and the aqua ligand are arranged axial. Oxidation of (NH4)2[Ir(NH3)Cl5] with Cl2 at 330 °C affords the tetragonal IrIV complex (NH4)[Ir(NH3)Cl5] (P4nc, Z = 2, a = 702.68(5); c = 912.89(9) pm). Its structure was determined using the powder diagram. Oxidation of (NH4)2[Ir(NH3)Cl5] with Br2 in water, on the other hand, gives (NH4)2[IrBr6] crystallizing in the K2[PtCl6] type. Oxidation of (PPh4)2[Ir(NH3)Cl5] with PhI(OAc)2 in CH2Cl2 affords the IrV amido complex (PPh4)[Ir(NH2)Cl5]. 相似文献
195.
以N,N′-二(4-甲氧基水杨基)邻苯二胺(H2L)为配体合成了2个新的稀土配合物[M_2L_3(H_2O)](M=Tb (1),Dy (2)),并对它们进行了红外分析、元素分析和单晶结构分析。单晶衍射结果表明,配合物1和2均为三明治型双核配合物。此外还研究了配合物1和2的磁学性质,结果表明配合物1和2都表现出反铁磁性作用和场诱导效应引起的慢弛豫行为。配合物2的有效能垒和驰豫时间分别为35.45 cm-1和2.7×10~(-10) s。 相似文献
196.
Beatriz Lozano-Torres M. Dolores Marcos Teresa Pardo Félix Sancenón Knut Rurack 《Journal of Coordination Chemistry》2018,71(6):786-796
AbstractProbe 1, which contains an anilinopyridine chromophore and an aza-oxa macrocyclic subunit, presented an absorption band centered at 340 nm in acetonitrile. Addition of Fe(III), Cr(III) and Hg(II) induced the growth of a new absorption band at 430 nm (with color change from colorless to yellow), whereas in the presence of Cu(II), Zn(II) and Pb(II), less marked changes were observed. The color changes observed upon addition of Fe(III), Cr(III) and Hg(II) were ascribed to the formation of 1:1 stoichiometry complexes with probe 1. Coordination of Fe(III), Cr(III) and Hg(II) with the pyridine fragment of 1 induced an enhancement of the charge transfer character accompanied with a marked bathochromic shift that was reflected in a color change from colorless to yellow. The strength of the interaction between probe 1 and Fe(III) cation was modulated upon interaction with anions. Of all the anions tested, only cyanide was able to induce the bleaching of the yellow 1·Fe(III) complex solution. This bleaching was ascribed to the formation of 1·Fe(III)-CN complex that restored, to some extent, the optical features of the free probe allowing the chromogenic sensing of cyanide. Besides, 1·Fe(III) complex was used to detect cyanide in acetonitrile-water 90:10 v/v mixtures with good recoveries. 相似文献
197.
Reactions of carbonate radical anion with amino-carboxylate complexes of manganese(II) and iron(III)
Amir Mizrahi Eric Maimon Haim Cohen Israel Zilbermann 《Journal of Coordination Chemistry》2018,71(11-13):1749-1760
AbstractThe reaction kinetics of eight amino-carboxylate complexes of Fe(III) and Mn(II) with carbonate radical anion were studied using the pulse radiolysis method and UV-vis spectroscopy. Difference spectra revealed the formation of Fe(IV) and Mn(III) after reaction with CO3??. Spectral measurements revealed the first step to be the coordination of carbonate to the metal center. All of these led to the conclusion that the role of coordinated carbonate is essential to the electron transfer process by carbonate radical anion. 相似文献
198.
AbstractIn strongly alkaline media ([OH?]?≥?0.12 M), nicotinamide (nica) forms a complex with square-planar Ag(OH)4? [nica]?≥?0.05 M. The complex decomposes in seconds to nicotinamide N-oxide. The correlation of maximum absorbance of the complex with concentrations of nicotinamide and hydroxide requires that the complex is either the five-coordinate Ag(OH)4(H-1nica)2? or the six-coordinate Ag(OH)5(nica)2?. Comparison with the reactions of Ag(OH)4? with nicotinate ion (nic?) and acetamide under similar conditions indicates that nicotinamide coordinates with Ag(OH)4? by the amido group rather than the nitrogen on the pyridine ring or the amido oxygen. Kinetics of the Ag(III)-nica redox reaction are consistent with direct reaction between nicotinamide and uncoordinated Ag(OH4)?. Oxidation takes place at the pyridine ring, yielding nicotinamide N-oxide. Silver(III) is reduced to monovalent silver. 相似文献
199.
Arenediazonium o-benzenedisulfonimides have been used as efficient electrophilic partners in Au(I) catalysed Suzuki coupling reactions. The synthetic protocol is general, easy and produced either biaryls or heteroaryl arenes in good yields (51 positive examples, average yield 80%). o-Benzenedisulfonimide was recovered at the end of the reactions and was reused to prepare the starting salts for further reactions. Mechanistic insights suggest that the o-benzenedisulfonimide anion act as an electron transfer agent and promotes a catalytic cycle which does not require the presence of photocatalysts or external oxidants. 相似文献
200.
Two polydentade Schiff base ligands and their Ru(III), Cr(III) and Fe(III) complexes were synthesized and characterized by elemental analysis (C, H, N), UV/Vis, FT IR, 1H and 13C NMR, LC–MS/MS, molar conductivity and magnetic susceptibility techniques. The absorption bands in the electronic spectra and magnetic moment measurements verified an octahedral environment around the metal ions in the complexes. The thermal stabilities were investigated using TGA. The synthesized complexes were used in the catalytic oxidation of 2-methyl naphthalene (2MN) to 2-methyl-1,4-naphthoquinone; vitamin K3, menadione, 2MNQ; using hydrogen peroxide, acetic acid and sulfuric acid. L1-Fe(III) complex showed very efficient catalytic activity with 58.54% selectivity in the conversions of 79.11%. 相似文献