Synthesis of some novel divalent transition metal complexes as antimicrobials

A novel series of transition metal complexes have been synthesized from the reaction of 5-((3-(methylthio)-5-(pyridin-4-yl)-4H- 1,2,4-triazol-4-ylamino)melhyl)quinolm-8-ol with transition metal salts.The structures of these compounds have been elucidated by elemental and spectral analysis.Furthermore,compounds were screened for in vitro antimicrobial activity against the representative panel of two Gram-positive and two Gram-negative bacteria and two strains of fungus.The various compounds show potent inhibitory action against test organisms.     

Molecular orbital studies of some transition metal complexes

A set of molecular orbital calculations based on a particular semi-empirical method, has been undertaken on a homologue series of bis(-2-methylallyl)transition metal (Ni, Co, Fe, Cr) complexes (abbreviated as ML₂). Arguments are found for predicting the stability of the NiL₂ system, which is the only one that could be synthetized.

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Zusammenfassung Eine Reihe von semiempirischen MO-Rechnungen wurde für die homologe Reihe von bis(-2-methylallyl) Metallkomplexen (Ni, Co, Fe, Cr) durchgeführt. Gründe für die Stabilität der Ni-Verbindung, die als einzige synthetisiert wurde, werden angeführt.

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Résumé Un ensemble de calculs par une méthode semi-empirique particulière d'orbitales moléculaires a été effectué sur une série homologue de complexes bis (-2-méthylallyl)-métal de transition (Ni, Co, Fe, Cr): ML₂.Certains arguments sont trouvés en faveur de la stabilité du système NiL₂, le seul à avoir été synthétisé.

     

Properties of some tetraphenylboronates of transition metal complexes

Summary Solid tetraphenylboronates of some cations,e.g. [Fe(1,10 phen)₃]³⁺ , [Co(NH₃)₆]³⁺, with E° values -0.26V are unstable, either thermally or photo chemically, or both. Products of such redox reactions are identified. The contrasting situation with more reducing cations,e.g. [Cr(en)₃ ]³⁺, is described.On leave from Paisley College of Technology, Renfrewshire, Scotland, U.K.     

On some transition metal complexes having orientational properties

The orientation properties of some complexes of chromium (III) or cobalt (II) with oxygen-containing ligands are presented. The orientation obtained is mostly homeotropic. The possibility of anchoring by coordination of liquid crystal (LC) molecules to the transition metal ion within the alignment layer is discussed on the basis of spectroscopic arguments.     

o-hydroxyaroyl-isonicotinoyl hydrazones as chelating agents with divalent transition metal ions

Summary Two series of bivalent metal complexes of the type M(Sal)· xH₂O and M(Naph) have been synthesized; where M = Co, Ni, Cu, Zn, Pd and Cd, and H₂-Sal and H₂-Naph are salicylaldehyde and o-hydroxynaphthaldehyde isonicotinoyl hydrazones which acted as dibasic terdentate ligands. The polymeric nature and coordination sites of the complexes have been characterized by elemental, d.t.a. and t.g.a analyses, molar conductance, pH, room temperature magnetic susceptibility and spectral (i.r., ¹H n.m.r, u.v.) measurements. The protonation constants of the ligands have been determined potentiometrically at different temperatures, ionic strengths and at different EtOH-H₂O compositions.     

Physical,chemical and biological studies on transition metal complexes of chelating tridentate ligand

Summary The interaction of 1-benzoin-4-phenylthiosemicarbazone (H₂ BPS) with some transition metal ions has been investigated. The ligand can function as a tridentate chelating agent, giving M(HBPS)₂ and M(BPS). Potentiometric studies proved that the mechanism of chelation is based on hydrogen ion liberation. Spectral studies in solution show that the ligand could be used for the microdetermination of Cu^IIions. On the basis of magnetic and spectral data, an octahedral structure is proposed for the Co^II and Ni^II complexes and a square-planar structure for the Cu^II complex. The corrosion inhibition of aluminium in Cl₃CCO₂H using H₂BPS is studied. The electrical conductivity of H₂BPS and of its complexes have been measured. The ligand shows an activation energy in the range of semiconducting materials. The antimicrobial activity of all compounds has also been demonstrated.     

Nicotinoyl hydrazide complexes of some first row transition metal ions

Summary Nicotinoyl hydrazide, L, complexes of the MLCl₂ · n EtOH type [M = manganese(II), iron(ll), cobalt(II), nickel(II) and copper(II); n = 0 or 1], WL₂) (NO₃)₂ [M = cobalt(II) and nickel(II)] and mixed metal complexes such as HgCo₂ L₂ Cl₆ and (NiL₂)HgI₄ have been prepared and their nature and structure studied by molar conductance, magnetic susceptibility, electronic, e.s.r. and i.r. spectral measurements. Octahedral structures have been proposed for all the complexes except MnLCl₂, CoLCl₂ and HgCo₂ L₂ C1₆ for which tetrahedral geometry is suggested.     

Thermal decompositions of some divalent transition metal complexes of triethanolamine

The thermal behaviours of the Ti(II), Mn(II), Fe(II), Ni(II), Cu(II) and Zn(II) complexes of triethanolamine were studied by means of thermogravimetry, differential thermogravimetry, differential thermal analysis infrared spectrophotometry and elemental analysis. The sequence of thermal stability of the metal complexes, determined by using the initial decomposition temperature, was found to be Ti(II)?Mn(II)>Fe(II)>Ni(II)>Zn(II)>Cu(II). Some of the kinetic parameters, such as the activation energy and order of reaction for the initial decomposition reaction, were calculated and the relationship between the thermal stability and the chemical structure of the complexes is discussed.     

Polyanionic N-donor ligands as chelating agents in transition metal complexes: synthesis, structural characterization and antiviral properties against HIV

We describe here the synthesis and characterization of new sulfonated and carboxylated-containing N-donor ligands [Na(4)(edts)]·4H(2)O (2), [Na(2)(dmeddp)]·2H(2)O (3) and [Na(4)(edtp)]·H(2)O (4) (edts = ethylene-diamine- N,N,N',N'-tetraethylenesulfonate ion; dmeddp = dimethyl-ethylene-diamine-N,N,N',N'-tetra-3-propionate ion; edtp = ethylene-diamine-N,N,N',N'-tetra-3-propionate ion) and their corresponding metal (Ni, Co, Cu and Zn) complexes. Mainly, UV-Vis and a computer aided analysis of the EPR spectra provided information on the geometry and structure of the complexes in solution. Some of the metal complexes inhibit HIV replication when treating both pre- and post-infected PBMC cells, and hustle the inhibitory effect compared to the metal salts alone.     

Synthesis of diferrocenylglyoxime and some of its transition metal complexes

Diferrocenylglyoxime has been prepared by the reaction of monolithioferrocene or dilithioferrocene with anti-dichloroglyoxime. Characterization of this novel vic-dioxime and some of its transition metal complexes are described.     

Divalent transition metal complexes

4-(4-ethoxy-phenylhydrazono)-1-phenyl-3-methyl-1H-pyrazolin-5(4H)-one (5a) (H-EMPhP) as ligand and its Cu(II), Co(II) and Ni(II) complexes 4(a-c) were synthesized and characterized by their thermal and spectral properties. The azocoupling product (H-EMPhP), able of azo-hydrazone tautomerism 5(a-d), act as a bidentate ligand involving in coordination the azogroup nitrogen of its common anion (7) and the oxygen atom that is bound to the pyrazole ring of the mentioned anion (7).     

Coordination and structure of some transition metal piperidinium pentamethylene dithiocarbamate complexes

Summary Cobalt(II), nickel(ll), and copper(II) complexes of piperidinum pentamethylene dithiocarbamate (pipmdte) have been prepared and studied by spectral (i.r. and absorption) and magnetic methods. The M(pipmdte)CI complexes are probably four coordinate and square planar, the tridentate ligand being coordinated via the two thiocarbamate sulphur atoms and the nitrogen atom of the piperidinium group.     

Acetone picolinoyl hydrazone complexes of some first row transition metal ions

Summary Acetone picolinoyl hydrazone (APH) complexes of the types M(APH)Cl₂nEtOH and M(APH-H)₂2EtOH (where M = manganese(II), iron(II), cobalt(II), nickel(II), or copper(II); n = 0 or 2) have been prepared and their nature and structures studied by molar conductance, molecular weight determination, thermal degradation, magnetic susceptibility, electronic and i.r. spectral measurements. Spin-free octahedral geometry has been proposed for all the complexes except Mn(APH)Cl₂ and Co(APH)Cl₂ for which tetrahedral geometry has been suggested.     

Synthesis and further reactivity studies of some transition metal gallyl complexes

Reactions of the anionic gallium(I) heterocycle salt, [K(tmeda)][Ga(DAB)] (DAB = {N(Dip)C(H)}₂; Dip = C₆H₃Prⁱ₂-2,6), with a series of groups 6-9 and 11 metal halide complexes have given rise to the metal gallyl complexes, [CpCr(IMes){Ga(DAB)}] (IMes = :C{(Mes)NC(H)}₂; Mes = mesityl), [M(tmeda){Ga(DAB)}₂] (M = Mn, Fe or Co) and [Cu(dppe){Ga(DAB)}] (dppe = 1,2-bis(diphenylphosphino)ethane). The majority of the complexes have been crystallographically characterized. The reactivity of the previously reported copper(I) gallyl complex, [(IPr)Cu{Ga(DAB)}] (IPr = :C{(Dip)NC(H)}₂), towards a variety of unsaturated substrates has been explored. Three crystallographically characterized complexes have arisen from this phase of the study, viz. [(IPr)CuCCPh], [(IPr)Cu{Ga(DAB)}(CNBu^t)] and [(IPr)Cu{κ¹-OC(O)C(CNHDip)(NHDip)}]. The results of these investigations show that the reactivity of [(IPr)Cu{Ga(DAB)}] is significantly different to that of related copper boryl complexes.     

Polyoxometalate tri-supported transition metal complexes containing mixed-valent transition metal ions

Three compounds, [AsMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·4H₂O (1), [PMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·3H₂O (2) and [PMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·3.5H₂O (3), have been synthesized under hydrothermal conditions and characterized by IR, UV–vis, XRD, TG, elemental analysis, and X-ray diffraction analysis. Single-crystal X-ray structure analysis reveals that 1 and 2 are isostructural and isomorphous, whereas 2 and 3 are polymorphs. Polymorphs of 1 have not been synthesized yet. The mixed-valent transition metal ion in 1–3 has been further confirmed by TG analyses. Catalytic properties of 1 and 2 have also been studied.     

Kinetics of thermal dehydration of some bis-salicylato-diaquo complexes of transition metal ions

The kinetics of thermal dehydration of bis-salicylato-diaquo complexes of VO(II), Cu(II), Ni(II), Co(II), Fe(II), Mn(II) and Zn(II) were studied. The activation energies and other kinetic parameters were evaluated. The observed kinetic parameters indicate first-order reactions. The activation energy of the thermal dehydration decreases in the sequence VO(II) > Cu(II) > Zn(II) > Co(II) > Ni(II) > Fe(II) > Mn(II), which is also the sequence for the difference in carboxyl group IR frequency.

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Zusammenfassung Die Kinetik der thermischen Dehydratisierung von Bis-salicylato-diaquo-Komplexen von VO(II), Cu(II), Ni(II), Co(II), Fe(II), Mn(II) und Zn(II) wurden untersucht. Aktivierungsenergien und andere kinetische Parameter wurden bestimmt. Die beobachteten kinetischen Parameter weisen auf Reaktionen erster Ordnung hin. Die Aktivierungsenergie der thermischen Dehydratisierung nimmt in der Reihenfolge VO(II) > Cu(II) > Zn(II) > Co(II) > Ni(II) > > Fe(II) > Mn(II) ab. In der gleichen Reihenfolge ändert sich auch die IR-Frequenz der Carbonylgruppe.

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-- , , , , , . , . VO(II) > Cu(II) > Zn(II) > Co(II) > Ni(II) > Fe(II) > Mn(II). .

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The authors express their sincere thanks to the late Dr. M. D. Karkhanawala (then Head, Chemistry Division, BARE, India), for providing the facilities for TG and DTA, and also to the UGC (India) for research fellowships to the authors (BDH and SMA).