Mixed-ligand ternary complexes of potentially pentadentate but functionally tridentate Schiff base chelates
摘要:
The potentially pentadentate chelate 2,6-diacetylpyridine-bis(N-methyl-S-methyldithiocarbazate) (Nmedapsme) has been synthesized and structurally characterized by X-ray diffraction. Its reactions with nickel(II) salts did not lead to pentadentate coordinated ligand complexes but ternary complexes of general formula, INi(Nmedapsme)(nmesme)L]X center dot H2O (L = Br-, I- ; X =I-, BF4-) where Nmedapsme binds as a tridentate and nmesme = N-methyl-S-methyldithiocarbazate. The related ternary nickel(II) complexes of formula, Ni(Nmedapsme)(nmetsc)Br-2 has also been prepared and characterized. X-ray crystal structures of [Ni(Nmedapsme)(nmesme)I]I center dot H2O and INi(Nmedapsme)(nmestne)Br]BF4 center dot H2O revealed that, in these complexes, the Nmedapsme ligand acts as a tridentate NNN donor while the distal S-donors are not coordinated. The bidentate (NS) ligand, nmesme coordinates to the nickel(II) ion via the amino nitrogen and the thione sulfur atoms, the sixth coordination site is occupied by an anion. In both complexes, the nickel(II) ion adopts a distorted octahedral configuration. The complex [Cu(nmesme)(2)(ONO2)]NO3 was obtained from an unsuccessful attempt to complex copper(II) with Nmedapsme. Hydrolysis of the parent Schiff base Nmedapsme occurred during complexation. An X-ray crystallographic structure analysis shows that the complex, [Cu(nmesme)(2)(ONO2)]NO3 has an approximately square-pyramidal geometry with the two nmesme ligands coordinated to the copper(II) ion as NS bidentate chelating agents via the amino nitrogen and thione sulfur atoms and the fifth coordination position of copper(II) is occupied by a monodentate nitrate ligand. (C) 2010 Elsevier Ltd. All rights reserved.
The thermal decompositions of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of saccharin were studied in static air atmosphere. All of the complexes contain four molecules of coordination water and two molecules of crystallization water. The water molecules were removed in a single stage, except from the Zn(II) complex, which exhibited two endothermic effects. The dehydration process was usually accompanied by a sharp colour change. The anhydrous complexes exhibited a phase transition and the decomposition or combustion of saccharin occurred in the second and subsequent stages. The final decomposition products were identified by XRPD as the respective metal oxides. The kinetic parameters, such as the order of reaction and energy of activation for the dehydration stage, were evaluated and the thermal stabilities of the complexes are discussed.
Absolute asymmetric synthesis of five-coordinate complexes
作者:Anders Lennartson、Mikael Håkansson
DOI:10.1039/c5nj00254k
日期:——
of a five-coordinate complex. In this study, we discuss the chirality of five-coordinate enantiomers displaying mono- and bi-dentate ligands by optical resolution of three complexes. Through total spontaneous resolution, it was possible to obtain optically active bulk products starting from achiral precursors only. It was discovered that crystallisation of two of the complexes was influenced by undetectable
Catalytic Allylic Amination versus Allylic Oxidation: A Mechanistic Dichotomy
作者:Kimberly Smith、Christopher D. Hupp、Katherine L. Allen、Greg A. Slough
DOI:10.1021/om049052d
日期:2005.3.1
Allylic oxidation of hydrocarbon substrates is the foundation of many industrial and fine-chemical production processes. Direct allylic oxidation of cycloalkenes (C5-8) has been widely discussed in the chemical literature. However, certain mechanistic details related to the presence of allylic free radicals have yet to be fully resolved. The corresponding copper-catalyzed allylic amination reaction
Mixed-ligand ternary complexes of potentially pentadentate but functionally tridentate Schiff base chelates
作者:Mohammad Akbar Ali、Aminul Huq Mirza、Chiam Yin Yee、Hayatti Rahgeni、Paul V. Bernhardt
DOI:10.1016/j.poly.2010.11.019
日期:2011.2
The potentially pentadentate chelate 2,6-diacetylpyridine-bis(N-methyl-S-methyldithiocarbazate) (Nmedapsme) has been synthesized and structurally characterized by X-ray diffraction. Its reactions with nickel(II) salts did not lead to pentadentate coordinated ligand complexes but ternary complexes of general formula, INi(Nmedapsme)(nmesme)L]X center dot H2O (L = Br-, I- ; X =I-, BF4-) where Nmedapsme binds as a tridentate and nmesme = N-methyl-S-methyldithiocarbazate. The related ternary nickel(II) complexes of formula, Ni(Nmedapsme)(nmetsc)Br-2 has also been prepared and characterized. X-ray crystal structures of [Ni(Nmedapsme)(nmesme)I]I center dot H2O and INi(Nmedapsme)(nmestne)Br]BF4 center dot H2O revealed that, in these complexes, the Nmedapsme ligand acts as a tridentate NNN donor while the distal S-donors are not coordinated. The bidentate (NS) ligand, nmesme coordinates to the nickel(II) ion via the amino nitrogen and the thione sulfur atoms, the sixth coordination site is occupied by an anion. In both complexes, the nickel(II) ion adopts a distorted octahedral configuration. The complex [Cu(nmesme)(2)(ONO2)]NO3 was obtained from an unsuccessful attempt to complex copper(II) with Nmedapsme. Hydrolysis of the parent Schiff base Nmedapsme occurred during complexation. An X-ray crystallographic structure analysis shows that the complex, [Cu(nmesme)(2)(ONO2)]NO3 has an approximately square-pyramidal geometry with the two nmesme ligands coordinated to the copper(II) ion as NS bidentate chelating agents via the amino nitrogen and thione sulfur atoms and the fifth coordination position of copper(II) is occupied by a monodentate nitrate ligand. (C) 2010 Elsevier Ltd. All rights reserved.
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作者:H. Íçbudak、V. T. Yilmaz、H. Ölmez
DOI:10.1023/a:1010190701136
日期:——
The thermal decompositions of Mn(II), Fe(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of saccharin were studied in static air atmosphere. All of the complexes contain four molecules of coordination water and two molecules of crystallization water. The water molecules were removed in a single stage, except from the Zn(II) complex, which exhibited two endothermic effects. The dehydration process was usually accompanied by a sharp colour change. The anhydrous complexes exhibited a phase transition and the decomposition or combustion of saccharin occurred in the second and subsequent stages. The final decomposition products were identified by XRPD as the respective metal oxides. The kinetic parameters, such as the order of reaction and energy of activation for the dehydration stage, were evaluated and the thermal stabilities of the complexes are discussed.