Isomerization Processes on Organoruthenium Complexes Bearing κ2 (P,C )-Bidentate Ligands Generated Through Nucleophilic Addition to Coordinated Alkenyl Phosphanes

2018 ◽  
Vol 2018 (45) ◽  
pp. 4875-4886 ◽  
Author(s):  
Isaac García de la Arada ◽  
Josefina Díez ◽  
M. Pilar Gamasa ◽  
Elena Lastra
Keyword(s):  
Nucleophilic Addition ◽  
Bidentate Ligands ◽  
Isomerization Processes

New methods in asymmetric catalysis based on new hemi-labile bidentate ligands

2008 ◽  
Vol 80 (5) ◽  
pp. 881-890 ◽  
Author(s):  
André B. Charette ◽  
Alexandre Côté ◽  
Jean-Nicolas Desrosiers ◽  
Isabelle Bonnaventure ◽  
Vincent N. G. Lindsay ◽  
...  
Keyword(s):  
Asymmetric Catalysis ◽  
Nucleophilic Addition ◽  
Conjugate Addition ◽  
Bidentate Ligands ◽  
New Methods ◽  
Conjugate Reduction ◽  
Nitro Derivatives

Chiral bidentate hemi-labile bis(phosphine) monoxide ligands were shown to be quite effective in various copper-catalyzed transformations. Among them, the nucleophilic addition to imines, the conjugate addition to α,β-unsaturated nitro derivatives, and the conjugate reduction of α,β-unsaturated sulfones generally gave good to excellent yields and high enantiomeric excesses.

Complexes with New Chelate Anionic Ligands Formed by Nucleophilic Addition in Copper(II) Coordination Sphere. III. The Crystal Structures of (2,2'-Bipyridine-N,N')(cyanato-N)[methyl(2-cyano-2-imidoxy Ethaneimidate-N,N')]copper(II) and (2,2'-Bipyridine-N,N')(2-cyano-2-imidoxy Ethaneimidate-N,N')copper(II)

1999 ◽  
Vol 64 (4) ◽  
pp. 600-612 ◽  
Author(s):  
Michal Dunaj-Jurčo ◽  
Ivan Potočňák ◽  
Dušan Mikloš ◽  
Robert Klement
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Coordination Polyhedron ◽  
Nucleophilic Addition ◽  
Bidentate Ligands ◽  
Hydroxide Ion ◽  
Coordination Polyhedra ◽  
Anionic Ligands ◽  
Distorted Trigonal Bipyramid ◽  
Bonding Systems

Crystal structures of Cu(II) compounds with new chelate anionic ligands are presented. The formulae of these compounds are [Cu(bipy)(mcoe)(NCO)] (1) and [Cu(bipy)(coe)] (2), where bipy is 2,2'-bipyridine, mcoe and coe are the anionic chelate ligands methyl(2-cyano-2-imidoxy ethaneimidate), [(ON)(NC)C-C(NH)(OCH3)]1- (3), and 2-cyano-2-imidoxy ethaneimidate, [(ON)(NC)C-C(NH)(O)]2- (4), respectively, formed by nucleophilic addition of methanol and hydroxide ion to the coordinatively activated β-carbon of the nitroso-dicyanomethanide. Formation of the hydroxide ion from water in the reaction mixture can be explained by protonation of the C(CN)3- anion. The coordination polyhedra in 1 and 2 are quite different. The coordination polyhedron around the Cu(II) ion in 1 is a distorted trigonal bipyramid and in 2 a distorted square. The Cu(II) ion in 1 is coordinated by four N atoms from two bidentate ligands and one N atom from the NCO- group. The crystal structure consists of discrete molecules with {CuN5} chromophore. On the other hand, the Cu(II) ion in 2 is coordinated by four N atoms from two bidentate ligands in square coordination and the molecules are linked by weaker contacts between copper and oxygen atoms (Cu-O1i = 2.503(3), Cu-O2ii = 2.801(3) Å; i = -x, -y, -z + 1; ii = -x + 1, -y, -z + 1) to infinite chains parallel with c. Thus the coordination polyhedron is completed to an elongated tetragonal bipyramid with the {CuN4O*O*} chromophore. The angle O1i-Cu-O2ii is 167.9(1)° and the crystal structure cannot be considered as molecular but consisting of chains running in one direction. Inspection of the bond distances in mcoe and coe indicates strongly delocalized π-bonding systems. This is also supported by the fact that the anions are almost planar with bond angles close to 120°. The calculated Wiberg (bond-order) indices show that due to conjugation, the bonds within the metallocycle in mcoe and coe exhibit partially multiple character.

Recent Progress in Chemosensors Using Aldehyde-bearing Fluorophores for the Detection of Specific Analytes and their Bioimaging

2019 ◽  
Vol 26 (21) ◽  
pp. 4003-4028 ◽  
Author(s):  
Fangjun Huo ◽  
Yaqiong Zhang ◽  
Caixia Yin
Keyword(s):  
Biomedical Research ◽  
Nucleophilic Addition ◽  
Recent Progress ◽  
Biological Imaging ◽  
Tissue Imaging ◽  
Fluorescence Probes ◽  
Biological Applications ◽  
Convenient Procedure ◽  
Nucleophilic Mechanism

In recent years, aldehyde-appended fluorescence probes have attracted increasing attention. Fluorescent biological imaging includes many modern applications for cell and tissue imaging in biomedical research. Meanwhile, the nucleophilic mechanism is a very simple and convenient procedure for the preparation of aldehyde-sensing probes. This tutorial review focuses on aldehyde-bearing chemosensors based on nucleophilic addition mechanism with biological applications.

Formation of spiro adduct from N-methyl-N-(2,4,6-trinitrophenyl)glycine anion

1989 ◽  
Vol 54 (2) ◽  
pp. 440-445 ◽  
Author(s):  
Vladimír Macháček ◽  
Alexandr Čegan ◽  
Miloš Sedlák ◽  
Vojeslav Štěrba
Keyword(s):  
Nmr Spectroscopy ◽  
Dimethyl Sulfoxide ◽  
Equilibrium Constant ◽  
Mole Fraction ◽  
Nucleophilic Addition ◽  
Adduct Formation ◽  
First Case ◽  
C Nmr

The intramolecular nucleophilic addition of N-methyl-N-(2,4,6-trinitrophenyl)glycine anion in methanol-dimethyl sulfoxide mixtures produces spiro[(3-methyl-5-oxazolidinone)-2,1'-(2',4',6'-trinitrobenzenide)]. The spiro adduct has been identified by means of 1H and 13C NMR spectroscopy. This is the first case when the formation of a Meisenheimer adduct with carboxylate ion is observed. Logarithm of the equilibrium constant of adduct formation increases linearly with the mole fraction of dimethyl sulfoxide in its mixture with methanol.

Ligand isomerism in Pt(II) complexes – structural aspects

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Milan Melník ◽  
Peter Mikuš
Keyword(s):  
Mixed Ligand ◽  
Bidentate Ligands ◽  
Trans Isomers ◽  
Mean Values ◽  
Bite Angle ◽  
Coordination Spheres ◽  
Structural Aspects

Abstract This review has focused on ligand isomers in Pt(II) complexes. There are a variety of inner coordination spheres about the platinum(II) atom (PtN4, PtN2Cl2, PtP2Cl2, PtPNC2, PtPNCl2, PtP2CBr, PtP2CS), build up by mono- and bidentate ligands. The bidentate ligands create a variety of metallocyclic rings. The L–Pt–L bite angle (mean values) open in the sequence: 73.1° (PNP) < 78.7° (NC2C) < 80.4° (NC2N) < 86.4° (PC2P) < 86.7° (PNNP) < 93.0° (CC3S). There are three types of isomers: ligand, mixed – (ligand + distortion), and mixed – (ligand + cis-trans), isomers, which are rarity.

Regioselective Functionalization of N-Fused Heteroaromatics via FeCl3-Catalyzed Nucleophilic Addition to Activated N-Heterocycles

Synthesis ◽  
2020 ◽  
Author(s):  
Ikyon Kim ◽  
Sung June Kim ◽  
Sunhee Lee
Keyword(s):  
Aromatic Compounds ◽  
Nucleophilic Addition ◽  
Chemical Space ◽  
Wide Range ◽  
Regioselective Functionalization

AbstractBroadening of nitrogen-fused heteroaromatic chemical space such as indolizine and pyrrolo[1,2-a]pyrazine was achieved via FeCl­3-catalyzed nucleophilic addition of these N-fused aromatic compounds to a wide range of azolinium systems generated in situ, leading to novel N-fused heteroaromatic scaffolds with dearomatized N-heterocyclic substituents regioselectively. Nucleophilic addition of indolizines and pyrrolo[1,2-a]pyrazines mainly occurred at the C1 position of the isoquinoliniums and at the C4 site of the quinoliniums.

scholarly journals Complexes of Copper and Iron with Pyridoxamine, Ascorbic Acid, and a Model Amadori Compound: Exploring Pyridoxamine’s Secondary Antioxidant Activity

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 208
Author(s):  
Guillermo García-Díez ◽  
Roger Monreal-Corona ◽  
Nelaine Mora-Diez
Keyword(s):  
Antioxidant Activity ◽  
Ascorbic Acid ◽  
Rate Constant ◽  
Stable Complex ◽  
Aqueous Environment ◽  
Oh Radicals ◽  
Bidentate Ligands ◽  
Superoxide Radical Anion ◽  
Amadori Compound ◽  
The Stability

The thermodynamic stability of 11 complexes of Cu(II) and 26 complexes of Fe(III) is studied, comprising the ligands pyridoxamine (PM), ascorbic acid (ASC), and a model Amadori compound (AMD). In addition, the secondary antioxidant activity of PM is analyzed when chelating both Cu(II) and Fe(III), relative to the rate constant of the first step of the Haber-Weiss cycle, in the presence of the superoxide radical anion (O2•−) or ascorbate (ASC−). Calculations are performed at the M05(SMD)/6-311+G(d,p) level of theory. The aqueous environment is modeled by making use of the SMD solvation method in all calculations. This level of theory accurately reproduces the experimental data available. When put in perspective with the stability of various complexes of aminoguanidine (AG) (which we have previously studied), the following stability trends can be found for the Cu(II) and Fe(III) complexes, respectively: ASC < AG < AMD < PM and AG < ASC < AMD < PM. The most stable complex of Cu(II) with PM (with two bidentate ligands) presents a ΔGf0 value of −35.8 kcal/mol, whereas the Fe(III) complex with the highest stability (with three bidentate ligands) possesses a ΔGf0 of −58.9 kcal/mol. These complexes can significantly reduce the rate constant of the first step of the Haber-Weiss cycle with both O2•− and ASC−. In the case of the copper-containing reaction, the rates are reduced up to 9.70 × 103 and 4.09 × 1013 times, respectively. With iron, the rates become 1.78 × 103 and 4.45 × 1015 times smaller, respectively. Thus, PM presents significant secondary antioxidant activity since it is able to inhibit the production of ·OH radicals. This work concludes a series of studies on secondary antioxidant activity and allows potentially new glycation inhibitors to be investigated and compared relative to both PM and AG.

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