The interaction of aliphatic amines with transition-metal complexes of aromatic di-imines. Part 2. Concurrent nucleophilic attack at the central metal and co-ordinated ligand in the reaction between ethylenediamine and dichloro(5-nitro-1,10-phenanthroline)palladium(II) in dimethylformamide

1984 ◽  
pp. 2785 ◽  
Author(s):  
Antonino Bartolotta ◽  
Matteo Cusumano ◽  
Antonino Giannetto ◽  
Vittorio Ricevuto
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Aliphatic Amines ◽  
Nucleophilic Attack ◽  
Central Metal

New cyclizations via catalytic ruthenium vinylidenes

2008 ◽  
Vol 80 (5) ◽  
pp. 1167-1177 ◽  
Author(s):  
Jesús A. Varela ◽  
Carlos González-Rodríguez ◽  
Silvia G. Rubín ◽  
Luis Castedo ◽  
Carlos Saá
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Nucleophilic Attack ◽  
Terminal Alkynes ◽  
Pericyclic Reactions ◽  
Catalytic Metal ◽  
Cyclic Compounds

New carbocyclizations that proceed via catalytic metal-vinylidenes are presented. Metal-vinylidene catalytic species, which are easily accessible from terminal alkynes and catalytic amounts of transition-metal complexes, can be involved either in pericyclic reactions or in tandem processes triggered by nucleophilic attack at the electrophilic position of the vinylidene. In both cases, a wide variety of valuable cyclic compounds are easily accessible. Some recent carbocyclizations will be described.

scholarly journals Synthesis, Characterization, Biological Activity and DNA Binding Studies of Metal Complexes with 4-Aminoantipyrine Schiff Base Ligand

2012 ◽  
Vol 9 (1) ◽  
pp. 389-400 ◽  
Author(s):  
B. Anupama ◽  
M. Padmaja ◽  
C. Gyana Kumari
Keyword(s):  
Schiff Base ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Schiff Base Ligand ◽  
Metal Ion ◽  
Spectral Studies ◽  
Significant Activity ◽  
Central Metal ◽  
Binding Studies

A new series of transition metal complexes of Cu(II),Ni(II),Co(II), Zn(II) and VO(IV) have been synthesized from the Schiff base ligand (L) derived from 4-amino antipyrine and 5- bromo salicylaldehyde. The structural features of Schiff base and metal complexes were determined from their elemental analyses, thermogravimetric studies, magneticsusceptibility, molar conductivity, ESI-Mass, IR, UV-VIS,1H NMR and ESR spectral studies. The data show that the complexes have composition of ML2type. The UV-VIS, magnetic susceptibility and ESR spectral data suggest an octahedral geometry around the central metal ion. Biological screening of the complexes reveals that the Schiff base transition metal complexes show significant activity against microorganisms. Binding of Co(II) complex with calf thymus DNA (CT DNA) was studied by spectral methods.

scholarly journals Structural Properties and Reactive Site Selectivity of Some Transition Metal Complexes of 2,2′(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene))bis(phenylmethan-1-yl-1-ylidene)dibenzoic Acid: DFT, Conceptual DFT, QTAIM, and MEP Studies

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Fritzgerald Kogge Bine ◽  
Nyiang Kennet Nkungli ◽  
Tasheh Stanley Numbonui ◽  
Julius Numbonui Ghogomu
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Structural Properties ◽  
Transition Metal Complexes ◽  
Metal Ion ◽  
Density Functional ◽  
Conceptual Dft ◽  
Distorted Octahedral Geometry ◽  
Chemical Hardness ◽  
Central Metal

Herein is presented a density functional theory (DFT) study of reactivity and structural properties of transition metal complexes of the Schiff base ligand 2,2′(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene))bis(phenylmethan-1-yl-1-ylidene)dibenzoic acid (hereafter denoted EDA2BB) with Cu(II), Mn(II), Ni(II), and Co(II). The quantum theory of atoms-in-molecules (QTAIM), conceptual DFT, natural population analysis (NPA), and molecular electrostatic potential (MEP) methods have been used. Results have revealed a distorted octahedral geometry around the central metal ion in each gas phase complex. In the DMSO solvent, a general axial elongation of metal-oxygen bonds involving ancillary water ligands has been observed, suggestive of loosely bound water molecules to the central metal ion that may be acting as solvent molecules. Weak, medium, and strong intramolecular hydrogen bonds along with hydrogen-hydrogen and van der Waals interactions have been elucidated in the complexes investigated via geometric and QTAIM analyses. From the chemical hardness values, the complex [Co(EDA2BB)(OH2)2] is the hardest, while [Cu(EDA2BB)(OH2)2] is the softest. Based on the global electrophilicity index, the complexes [Ni(EDA2BB)(OH2)2] and [Cu(EDA2BB)(OH2)2] are the strongest and weakest electrophiles, respectively, among the complexes studied. In conclusion, the reactivity of the complexes is improved vis-à-vis the ligand, and stable geometries of the complexes are identified, alongside their prominent electrophilic and nucleophilic sites.

scholarly journals Designing, synthesis and spectral characterization of Schiff base transition metal complexes: DNA cleavage and antimicrobial activity studies

2008 ◽  
Vol 73 (11) ◽  
pp. 1063-1071 ◽  
Author(s):  
N. Raman ◽  
Syed Ali ◽  
Dhaveethu Raja
Keyword(s):  
Magnetic Susceptibility ◽  
Schiff Base ◽  
Transition Metal ◽  
Metal Complexes ◽  
Spectral Data ◽  
Transition Metal Complexes ◽  
Metal Ion ◽  
Spectral Studies ◽  
Central Metal ◽  
Elemental Analyses

A new series of transition metal complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been designed and synthesized using a Schiff base (L) derived from 4-aminoantipyrine, benzaldehyde and o-phenylenediamine. The structural features were derived from their elemental analyses, magnetic susceptibility and molar conductivity, as well as from mass, IR, UV-Vis, 1H-NMR and ESR spectral studies. The FAB mass spectral data and elemental analyses showed that the complexes had a composition of the ML type. The UV-Vis and ESR spectral data of the complexes suggested a square-planar geometry around the central metal ion. The magnetic susceptibility values of the complexes indicated that they were monomeric in nature. Antimicrobial screening tests were also performed against four bacteria, viz. Salmonella typhi, Staphylococcus aureus, Escherichia coli, and Bacillus subtilis and three fungi, viz. Aspergillus niger, Aspergillus flavus and Rhizoctonia bataicola. These data gave good results in the presence of metal ion in the ligand system. The nuclease activity of the above metal complexes shows that only the copper complex cleaves CT DNA in the presence of an oxidant.

Transition Metal Complexes of a Diaza-Crown Ether with two Carbamoylmethyl Substituents: Synthesis and Assessment as a Functional Nuclease

2017 ◽  
Vol 42 (2) ◽  
pp. 136-144
Author(s):  
Jia-qing Xie ◽  
Shu-lan Cai ◽  
Fa-mei Feng
Keyword(s):  
Transition Metal ◽  
Crown Ether ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Dna Cleavage ◽  
Catalytic Mechanism ◽  
Active Species ◽  
Lewis Acidity ◽  
Hydrolytic Cleavage ◽  
Central Metal

We report the synthesis, catalytic function and catalytic mechanism of two transition metal complexes (CuL, ZnL) of a diaza-crown ether with two acetylamino side arms [L = 2,2′-(1,4,10,13-tetraoxa-7,16-diazacyclooctadecane-7,16-diyl)diacetamide] in the hydrolysis of DNA. Their nuclease functions on pUC19 DNA cleavage were investigated. The results indicated that the active species might be formed by the deprotonation of the water-coordinated molecules in the complex and the optimum pH is 8.0 for both CuL and ZnL. The catalytic activity of CuL is higher than that of ZnL in DNA hydrolytic cleavage due to the difference in the Lewis acidity of the central metal ions, which is contrary to the result with the Cu and Zn complexes of the parent ligand L0 (1,4,10,13-tetraoxa-7,16-diazacyclooctadecane) as artificial nuclease. Comparison studies of DNA cleavage in the presence and absence of several oxygen scavengers showed that these complexes can promote DNA cleavage by a hydrolytic pathway. Our proposed mechanism suggests that the negative charge on the phosphorus oxygen atom of the substrate molecule is dispersed and the intermediate is formed and stabilised by hydrogen bonding between the DNA molecule and the acetylamino group of the complex.

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