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Synthesized Complexes (synthesized + complex)
Selected AbstractsSynthesis and Structure of Trialkyltantalum Complexes Stabilized by Aminopyridinato LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006Awal Noor Abstract (4-Methylpyridin-2-yl)(trimethylsilyl)amine (1), (6-methylpyridin-2-yl)(trimethylsilyl)amine (2), and (2,6-diisopropylphenyl)(pyridin-2-yl)amine (3) were deprotonated and used as ligands to synthesize trialkyltantalum complexes. The reaction of 2 equiv. of 1 or 2 with pentabenzyltantalum afforded tribenzyltantalum(V) complexes by toluene elimination. Analogous reaction using 3 failed. Lithiation of 3 followed by the reaction with tribenzyltantalum dichloride gave rise to the corresponding tribenzyl complex. Other alkyltantalum complexes stabilized by this ligand environment can be prepared by treating tantalum pentachloride with 2 equiv. oflithiated 3 to form a bis(aminopyridinato)tantalum trichloride. The reaction of this trichloride with 3 equiv. of alkyllithium compounds like methyllithium affords the corresponding trialkyltantalum complexes. X-ray diffraction studies of four of the synthesized complexes were carried out. They adopt two different coordination environments, either slightly distorted capped octahedrons (sterically less demanding aminopyridinato ligands) or pentagonal bipyramids (bulkier aminopyridinato ligands). The alkyl species were surprisingly stable at elevated temperatures and no formation of mixed alkyl/alkylidene complexes was observed. Alkyl cation formation and the behaviour of a selection of these compounds in olefin polymerization were explored. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Proton and metal-ion activation of C,H exchange in five-membered azolesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2002Erwin Buncel Abstract Factors influencing C,H isotopic exchange rates in five-membered azoles, that is imidazoles and thiazoles, under catalysis by H+ and Mn+, especially transition metals, Pt(II) and Co(III) are discussed. Hydrogen ion catalysis through N(3) protonation of azoles 1,3 is generally the most efficient, with rate enhancements in the range 102,109 over the neutral process being attained. Metal-ion coordination also results in effective catalysis, though less so than catalysis by protons. Catalysis of C,H exchange by Mn+ can be studied through addition of the metal salts to a buffered solution of the heterocycle in which labile complexes exist, or on synthesized complexes such as 4,13 which are substitution-inert thus precluding complications from unknown dissociation equilibria. A delicate balance of factors influence the ease of C,H exchange, including: (1) the magnitude of the fractional charge located at N(3) of the heterocycle through Mn+,N(3) , bond polarization; (2) metal-to-ligand , back-bonding; (3) the electronic structure of the metal ions. These considerations have obvious consequences for deuterium- and tritium-labelling of a number of biomolecules, e.g. proteins, enzymes, nucleic acids, some vitamins, as well as drugs which incorporate five-membered azoles in their structures. Copyright © 2002 John Wiley & Sons, Ltd. [source] Synthetic, spectral as well as in vitro antimicrobial studies on some bismuth(III) bis(N,N -dialkyldithiocarbamato) alkylenedithiophosphatesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 4 2010H. P. S. Chauhan Abstract Mixed sulfur donor ligand complexes of the type bismuth(III) bis(N,N -dialkyldithiocarbamato) alkylenedithiophosphate, [R2NCS2]2BiS2POGO [where R = CH3 and C2H5; G = -CH2 -C(C2H5)2 -CH2 -, -CH2 -C(CH3)2 -CH2 -, -CH(CH3)-CH(CH3)- and -C(CH3)2 -C(CH3)2 -] were synthesized in 1:1 molar ratio of bismuth(III) bis(N,N -dialkyldithiocarbamate) chloride and ammonium alkylenedithiophosphate in refluxing benzene and characterized by melting point, molecular weight determinations, elemental analysis (C, H, N, Bi and S) and spectral [UV, IR,NMR (1H,13C and 31P) and powder X ray diffraction] studies; all these studies were in good agreement with the synthesized complexes. These newly synthesized derivatives are yellow and brown colored solids and are soluble in common organic solvents like benzene, chloroform, dichloromethane and DMF. Based on the physicochemical and spectral studies, a tentative structure of these newly synthesized complexes was assigned and the average particle size of the synthesized complexes determined by powder XRD, showing that nano range polycrystalline particles were formed with a monoclinic crystal system. These complexes were also screened for their antimicrobial activities using the well diffusion method. The free ligands as well as their mixed metal complexes were tested in vitro against four bacterial strains: two Gram-positive, Staphylococcus aureus (ATCC 9144) (G+) and Bacillus subtilis (ATCC 6051), (G+) and two Gram-negative, Escherichia coli (ATCC 9637) (G,) and Pseudomonas aeruginosa (ATCC 25619) (G,) to assess their antimicrobial properties. The results were indeed positive and exhibited good antibacterial effects. Chloroamphenicol used as a standard for comparison and synthesized complexes showed good antibacterial effects over chloroamphenicol. On the basis of these studies, the synthesized complexes help to understand the different structural and biological properties of main group elements with sulfur donor ligands. Copyright © 2010 John Wiley & Sons, Ltd. [source] Synthesis, structural characterization, biological activity and thermal study of tri- and diorganotin(IV) complexes of Schiff base derived from 2-aminomethylbenzimidazoleAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 11 2009Mala Nath Abstract This report deals with the synthesis and structural features of tri- and diorganotin(IV) complexes of the general formulae, RnSn(L)m [n = 3, m = 1, R = Me, n -Bu and Ph; n = 2, m = 2, R = Me, n -Bu, n -Oct and Ph; HL = Schiff base derived from the condensation of 2-aminomethylbenzimidazole (ambmz) and salicylaldehyde (abbreviated as HL or Hsal-ambmz)]. The newly synthesized complexes were characterized by elemental analysis, molar conductance, electronic, infrared, far-infrared, 1H NMR, 13C NMR, 119Sn NMR and 119Sn Mössbauer spectral studies. Thermal studies of all of the synthesized complexes were also carried out using thermogravimetry,differential thermal analysis-derivative thermogravimetric (TG-DTA-DTG) techniques. The residues thus obtained were characterized by infrared and powder X-ray diffraction analysis. The bioassay results of anti-inflammatory activity (using the carrageenan-induced paw edema bioassay in rats) and acute toxicity (LD50) of the synthesized derivatives indicated that diorganotin(IV) derivatives (19.75,22.23% inhibition) show better activity as compared with triorganotin(IV) derivatives (10.32,17.86% inhibition). Copyright © 2009 John Wiley & Sons, Ltd. [source] Antibacterial, spectral and thermal aspects of drug based-Cu(II) mixed ligand complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2009G. J. Kharadi Abstract The antibiotic agent clioquinol is well known for its drug design and coordinating ability towards metal ions. Copper(II) mixed-ligand complexes of clioquinol with various uninegative bidentate ligands were prepared. The structure of the synthesized complexes was characterized using elemental analyses, infrared spectra, 1H-NMR spectra, electronic spectra, magnetic measurements, FAB mass spectrum and thermo gravimetric analyses. The kinetic parameters such as order of reaction (n) and the energy of activation (Ea) are reported using the Freeman,Carroll method. The pre-exponential factor (A), the activation entropy (,S#), the activation enthalpy (,H#) and the free energy of activation (,G#) were calculated. Complexes were also screened for their in vitro antibacterial activity against a range of Gram-positive and Gram-negative bacteria in order to set the precursors for anti-tumourigenic agent. Copyright © 2009 John Wiley & Sons, Ltd. [source] Metal-based antitumor, cytotoxic and antimicrobial activity: pharmacological evaluation of Knoevenagel condensate ,-diketone Schiff base thiosemicarbazone Cu(II) and Zn(II) complexesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2009N. Raman Abstract Knoevenagel condensate Schiff base ligands [L = 3-cinnamalideneacetylacetone-thiosemicarbazone (CAT)/3-cinnama- lideneacetylacetoneethylthiosemicarbazone (CAET)/3-cinnamalideneacetylacetonephenylthiosemicarbazone (CAPT)] and their copper/zinc complexes were synthesized. They were characterized by analytical and spectral techniques. From these data it was found that the ligands adopt square-planar geometry on metalation with Cu2+ and Zn2+. To evaluate the antitumor and cytotoxic activity of the synthesized complexes in mice and human cancer cell lines, the antitumor activity of the complexes was evaluated against an Ehrlich ascites carcinoma (EAC) tumor model. The activity was assessed using survival time and short-term in vitro cytotoxic activity. Oral administration of complexes (100 mg/kg) increased the survival time. The cytotoxic activity of complexes was evaluated using human breast cancer (MDA-MB-231), colon cancer (HCT-116) and nonsmall lung cancer (NCI-H-23) cell lines. Both the complexes possessed significant antitumor and cytotoxic activity on EAC and human cancer cell lines. The in vitro antimicrobial screening effect of the investigated compounds was also tested against the various organisms by well diffusion method. Copyright © 2009 John Wiley & Sons, Ltd. [source] |