Top PDF Structural Studies of Diethylphenylphosphonite-Transition Metal Complexes

Structural Studies of Diethylphenylphosphonite-Transition Metal Complexes

Structural Studies of Diethylphenylphosphonite-Transition Metal Complexes

Since phosphine hydride complexes are notoriou sly non-rigid in solution , the n.m.r. data should not be taken.[r]

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Studies of transition metal nitrite complexes

Studies of transition metal nitrite complexes

Bonding parameters have been derived for the nitrite ligands, and the parameters are shown to be transferable to other complexes with the same transition metal ion and different nitri[r]

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Synthesis and structural studies of N   and O   donor complexes of  transition and post transition metal halides

Synthesis and structural studies of N and O donor complexes of transition and post transition metal halides

methylene ammonium cation is obtained as the oxidation product of trimethylamine, but the nature of the Cu(I) reduction product is not clear. In our studies further purification of the yellow solid via a Soxhlet extraction with boiling benzene provided a bright yellow solid with a sharp melting point 154 - 155 ° c. Micro-analytical data corresponds with the mono adduct CmCh-i iNtie, - identical with that of Lane and Yoke. The ir spectrum shows all the bands of co-ordinated trimethylamine ( 1 265 cm1, 999 cm1, 830 cm-' and 564 cm-') and the far ir has two bands below 400 cm-1 at 250 cm ' and 204 cm-' assigned to Cu-Cl stretching modes. The electronic spectrum has a "d-d"
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Structural studies of transition metal compounds

Structural studies of transition metal compounds

(For both film and diffractometer data sets~ weights were adjusted so that values, averaged over ranges of /F/ , A._, Sin8' and reflection indices, of the functio[r]

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Structural studies on some bivalent metal complexes

Structural studies on some bivalent metal complexes

The order of donor strengths of the halogen atoms can be used to rationalise the influence of the halogen upon the structures of the (RgP)CdX2 complexes in the solid state. The weaker donating halogens give rise to the more extented pentaco- ordinate structures e.g. (Et2p)CdX2 [x = Cl, Br ] , whereas the stronger donating iodine gives rise to the less -extended iodine-bridged dimer. Similarly while ct-(Cy^P^dC^ adopts a tetrametic structure, the bromide and iodide derivatives are dimeric. Thus the electron density donated by the stronger donor halogen is sufficient as to require only a tetraco-ordinate dimeric species to be formed. When the electron density donated by the halogen is decreased, a more-extended structure is formed.
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Synthesis and description of transition metal complexes and antimicrobial studies

Synthesis and description of transition metal complexes and antimicrobial studies

______________________________________________________________________________ ABSTRACT Mixed ligand complexes of transition metal with 8-quinolinols and 5-Alkoxumethyl-8-quinolinol have been prepared. Structural, spectroscopic and thermal properties have been studied on the basis of infrared spectra, Mass spectra, NMR spectra, electronic spectra, and elemental analyses. Also their antibacterial activities against Gram – ve (Escherichia coli and Ps. Aeruginosa Bacillus subtilis) and Gram +ve (Becillus megaterium and S.taphylococcus aureus) and antifungal activities again Aspergillus niger and Trichothesium Sp. have been carried out. All the tested complexes show higher antibacterial activity as compared to free ligand.
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Synthesis and Spectral Studies of Some Transition metal Complexes

Synthesis and Spectral Studies of Some Transition metal Complexes

INTRODUCTION Schiff bases are an important class of ligands in coordination chemistry and their complexing ability containing different donor atoms is widely reported 1,2 . The chemistry of Transition metal complexes containing schiff bases continues to be of interest on account of their interesting structural features and also because of their biological importance 3,4 .

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Reactivity and structural studies of metal complexes bound to DNA

Reactivity and structural studies of metal complexes bound to DNA

Comparisons with Other Studies. As described previously, Geise and co- workers have recently reported a limited study of the effect of intervening mismatches on long-range guanine oxidation (10), and they concluded that any attenuation in long-range oxidation arose from a competition between trapping of a guanine radical at the mismatch site versus hole transport; at a guanine-containing mismatch, the guanine radical would be more accessible and, hence, easier to trap. The oxidant used as well as assemblies in which charge transport is measured differ from those described here, and that may lead to some differences between the two systems with respect to relative yields. Nonetheless, the proposed explanation of Geise and co-workers for attenuation of yield in the presence of intervening mismatches is clearly invalid here. It is evident from the results that mismatches that do not contain guanines, in fact, lead to the largest attenuation in the yield of long-range guanine oxidation. Guanine-containing mismatches instead cause at most only small perturbations in long-range charge transport. Therefore, competitive hole trapping at the mismatch site does not appear to be a key factor governing the efficiency of electron transport. Solvent accessibility is clearly, however, a more
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Studies of some transition metal complexes of biguanide and related ligands

Studies of some transition metal complexes of biguanide and related ligands

metal or not. The possibility of conjuga:bion in the chelate ring has not even been discussed previously althmtgh the ligand would probably lend itself readily to s[r]

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Spectral studies on transition metal complexes with novel tridentate aroylhydrazones

Spectral studies on transition metal complexes with novel tridentate aroylhydrazones

The coordination of azomethine nitrogen with metal ion is further supported by the presence of new bands in the far IR region 340-370 cm -1 assignable to ʋ(M-N) for complex [11]. The characteristic absorption band at 1565-1590 cm -1 and 725-750 cm -1 respectively, are assignable to ʋ (C C ),and ʋ(C-H) of the benzene ring ligand and complexes. The pyridine ring stretching, in plane ring deformation and out of plane ring deformation vibrations are found at 1480 cm -1 ,610 cm -1 and 505 cm -1 respectively in the ligands and remain unaffected in the complexes. The new absorption band at 3290-3390 cm -1 in Cr(III), Mn(II), Fe(II) and Zn(II) complexes are assignable to stretching vibrations of the crystal water involved in two complexes. In the far IR region two new bands around 420-450 cm -1 and 300-340 cm -1 in complex can be assigned to ʋ(M-O) and ʋ(M-N) respectively.
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Synthetic and Structural Studies of Some Bivalent Transition Metal Complexes with Oxygen and Nitrogen Containing Schiff Base

Synthetic and Structural Studies of Some Bivalent Transition Metal Complexes with Oxygen and Nitrogen Containing Schiff Base

Yield-65-70%. RESULTS AND DISCUSSION The important infrared frequencies of the ligand and its complexes along with their tentative assignments are given in Table-2. The IR spectra of the ligand exhibit strong and broad band at 3300 cm -1 assigned 17 ν N–H vibrations. In the spectra of the complexes this band suffered downward shift proposing coordination through N-atom of primary amino group. A medium intensity band at 1580 cm -

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STRUCTURAL STUDIES AND CRYSTAL ENGINEERING OF DITHIADIAZOLYL RADICALS AND THEIR METAL COMPLEXES

STRUCTURAL STUDIES AND CRYSTAL ENGINEERING OF DITHIADIAZOLYL RADICALS AND THEIR METAL COMPLEXES

100 With regard to future work, it is clear that polymorphism is rife in DTDA chemistry. The first step that should be taken is to control crystallization conditions to isolate phase pure material. 9, 10 A series of studies of vapor pressure, enthalpy of sublimation etc coupled with calculations of intermolecular interactions will provide more quantitative insight into relative polymorph stability. In particular, 1β and 2β would be of interest to study magnetically. Serendipity will continue to play a role in the discovery of these new phases for the time being. However as more examples of radicals grown under controlled sublimation conditions are gathered, the selective formation of different polymorphs or single-phase molecular architectures will no doubt become a more strategic, pre-planned phenomenon.
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Low-temperature protonation studies of transition metal alkyl complexes and the synthesis and characterization of early transition metal PCP pincer complexes and two-coordinate alkylamido complexes

Low-temperature protonation studies of transition metal alkyl complexes and the synthesis and characterization of early transition metal PCP pincer complexes and two-coordinate alkylamido complexes

Introduction The study of alkane σ-complexes is motivated, in large part, by the desire to understand the mechanism of alkane C-H bond activation processes, and thus aid in the development of efficient and selective C-H activation catalysts. One such C-H activation process of great interest is the partial oxidation of methane to methanol. Methane is an abundant natural resource which is currently being underutilized due to the cost of its capture, transport, and storage. A cost-efficient process to convert methane into a methanol would enable the use of this natural resource in our liquid-fuel infrastructure as well as increase the utility of methane as a chemical feedstock. 1 Heterogeneous catalysts suffer from over-oxidation of methane; the C-H bonds of methanol are weaker than those of methane. Recent work with copper zeolites addresses the issue of selectivity by employing low conversion rates or stepwise procedures. 2
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STRUCTURAL STUDIES OF DITHIOCARBAMATE METAL COMPLEXES AND DICARBOXLIC ACID METAL SALTS JIMMY AHMAD

STRUCTURAL STUDIES OF DITHIOCARBAMATE METAL COMPLEXES AND DICARBOXLIC ACID METAL SALTS JIMMY AHMAD

5 interest in low spin and high spin cross-over phenomenon in an iron complex (Butcher & Sinn, 1976; Healy & Sinn, 1975). Dithiocarbamates reported complexes complement the theory of unoccupied d orbitals to give square planar, tetrahedral, and octahedral or other geometries. These metal complexes usually are showing homonuclear or dimeric structures. Homonuclear complexes may consist of one metal centre with various numbers of ligands while dimeric may compose of two metal centres with one or more bridging ligands. There are times where a polymeric structure was also obtained using the dithiocarbamates functional groups. This kind of structure had triggered interest of many chemists to create an infinite array of metal centres extending into 1, 2 or 3 dimensions.
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Synthesis, physicochemical and antimicrobial  studies of first row transition metal complexes

Synthesis, physicochemical and antimicrobial studies of first row transition metal complexes

niger, P. triticena and F. species). Antimicrobial studies shows that the Mn (II) complexes are more toxic than other metal complexes. Magnetic susceptibility measurements reveal octahedral geometry around the metal ion. The complexes were found to be non electrolyte in nature on the basis of low value of molar conductance.

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STUDIES ON THE SYNTHESIS AND CHARACTERIZATION OF THE TRANSITION METAL COMPLEXES OF NOVEL MANNICH BASE

STUDIES ON THE SYNTHESIS AND CHARACTERIZATION OF THE TRANSITION METAL COMPLEXES OF NOVEL MANNICH BASE

During last two decades, there has been increased research activity in the field of organometallic complexes particularly derived from Mannich bases. Mannich reaction is a three component condensation in which a compound containing an active hydrogen ( substrate) is reacted withformaldehyde and a secondary amine.It is a prototype of carbon-carbon bond forming reaction involves the addition resonance stabilized nucleophile to iminiumions.During the course of the reaction, three compounds condense with concomitant release of water to produce a new base, called Mannich base in which the active hydrogen in the substrate is replaced with an aminomethylgroup.The formation of both C-C bond and C-N bond makes this reaction a extremely useful synthetic procedure.Literature survey reveals that some Mannich bases possess broad spectrum biological activities which include Antineoplastic 1 , Antibacterial 2,3 ,
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Synthesis and structural characterization of some transition metal complexes with cyclic N2OS2 ligand

Synthesis and structural characterization of some transition metal complexes with cyclic N2OS2 ligand

The great interest in synthetic macrocycles and their corresponding metal complexes is related to the fact they can mimic naturally- occurring macrocyclic molecules in their structural features. The formation of macrocyclic complexes depends significantly on the dimension of the internal cavity, on the rigidity of macrocycle, on the nature of its donor atoms and on the complexing properties of the counterion.The syntheses of the macrocyclic ligands are generally carried out in the presence of a suitable salt. [4].

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Transition Metal Complexes of Dibenzyl Tetraazamacrocycles

Transition Metal Complexes of Dibenzyl Tetraazamacrocycles

(Prof. Tim Hubin, Department of Chemistry) Tetraazamacrocycles, cyclic molecules with four nitrogen at- oms, have long been known to produce highly stable transition metal complexes. Cross-bridging such molecules with 2-car- bon chains has been shown to enhance the stability of these complexes even further, providing enough stability to use the resulting compounds in applications as diverse and demanding as aqueous, green oxidation catalysis all the way to drug mol- ecules injected into humans. Although the stability of these compounds is believed to result from the increased rigidity and topological complexity imparted by the cross-bridge, there is insufficient experimental data to exclude other causes. In this study, standard organic and inorganic synthetic methods were used to produce unbridged dibenzyl tetraazamacrocycle ana- logues of known cross-bridged tetraazamacrocycles and their transition metal complexes to allow direct comparison of mol- ecules identical except for the cross-bridge. The syntheses of the known tetraazamacrocycles and the novel transition met- al complexes were successful with high yields and purity. Ini- tial chemical characterization of the complexes by UV-Visible spectroscopy and cyclic voltammetry shows little difference in electronic properties from bridged versions. Direct comparison studies of the unbridged and bridged compounds’ stabilities re- main to be carried out and will shed light on the importance of the cross-bridge to complex robustness.
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Synthesis and Structural Studies on Some Transition metal complexes of Bis-(benzimidazole-2-thio) ethane, propane and butane ligands

Synthesis and Structural Studies on Some Transition metal complexes of Bis-(benzimidazole-2-thio) ethane, propane and butane ligands

All chemical were of reagent grade, were used as supplied (Fluka) or (B.D.H). Elemental analyses (C.H.N and S) were carried out using micro analytical techniques on Perkin Elmer 2400 (IEES) at AL-AL-bayt University (Jordon). Metal estimation were done on PYE UNICAM SPg atomic absorption spectro-photometer. The chloride was determined using the method in Vogel 20 . Conductivity measure- ements for 10 -3 M solution of the complexes in (DMF) were carried out with on Jenway 4070 conductivity meter and a dip cell with platinized electrode. Infrared spectra were recorded on a FTIR Brucker Tensor 27co spectrophotometer in the 200-4000 cm -1 range using CsI discs. The UV/Vis spectra were recorded on a Shimadzu UV-160 spectrophoto- meter for 10 -3 M solution of
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Synthesis, characterization and biological studies of sulfadiazine drug based transition metal complexes

Synthesis, characterization and biological studies of sulfadiazine drug based transition metal complexes

The metal complexes of sulfadiazine drug have gained considerable importance due to their pronounced biological activity. A series of transition metal complexes of the above drug have been prepared and characterized by elemental analysis, molar conductance, electronic spectra, FT-IR, thermogravimetric analysis, proton NMR and cyclic voltammetry techniques. The electronic spectra of the ligand and complexes revealed the octahedral geometry for Ni(II) and Co(II)complexes and distorted octahedral geometry for Cu(II)complex. The corresponding infrared spectra suggest that the ligand behaves bidentate and confirm the presence of water molecules in the coordination sphere. The NMR spectral studies established changes in chemical shift of sulfa-imino proton and free –NH 2 group of ligand indicating complexation involving these groups. The thermal stability of the complexes has been studied by thermogravimetric and differential scanning calorimetry, which support the presence of water ligand and metal. The complexes exhibit an octahedral geometry around the metal Centre. The cyclicvoltammetric studies of the metal complexes showed that all but the cobalt complex exhibit an irreversible electron transfer redox processes. The cobalt complex, however, revealed a quasi-reversible behavior. The antimicrobial studies of synthesized metal complexes and ligand were screened for antibacterial activity against bacteria such as Escherchia coli, Staphylococcus aureus, Pseudomonousaureginosa and antifungal activity against P. Aeruginosa and Candida albicans species. Metal complexes of sulfadiazine drug exert a greater effect on the antimicrobial activities than the ligand drug
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