Synthesis and spectroscopic studies on 3-isonicotinamidorhodanine complexes of some bivalent metal ions

Summary 3-Isonicotinamido-rhodanine (HINRd) reacts with metal ions to yield complexes of the types M(INRd)OH·nH₂O (where M=Co^II, Ni^II, Zn^II or Cd^II and n=1 or 2), Cu(HINRd)X·2H₂O (where X=Cl or Br), Pd(HINRd)Cl₂ and Cd(HINRd)X₂·H₂O (where X=Cl or Br), depending on the metal salt used and the reaction conditions. The metal complexes have been characterized by elemental analysis, molar conductivities, molecular weights, magnetic susceptibility, visible, and i.r. studies. The i.r. spectra show that HINRd binds in a bidentate or monodentate manner. The spectral and magnetic studies suggest a tetrahedral arrangement for Co^II, octahedral for Ni^II and square-planar for Pd^II. HINRd behaves as a reducing agent towards Cu^II chloride or bromide forming diamagnetic Cu^I complexes.     

Synthesis,characterization, electrical and biological studies on some bivalent metal complexes

Metal complexes of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) with Schiff base derived from 2,5-dihydroxyacetophenone and s-benzyldithiocarbazate have been synthesized and characterized by elemental analysis, thermogravimetric analysis, molar conductance, molecular weight, magnetic susceptibility measurements, and electronic and infrared spectra. The molar conductivity data show them to be nonelectrolytes. The Schiff base behaves as a tridentate dibasic ONS donor towards metal ions. Thermal analyses indicate the presence of water in the complexes, making them six and four coordinates. The solid state electrical conductivity of the ligand and its complexes has been measured in the temperature range 313–414 K and the complexes are found to show semiconducting behavior. The antibacterial activities of the ligand and its complexes have also been screened against various organisms and it is observed that the coordination of metal ions has a pronounced effect on the bacterial activity of the ligand.     

Synthesis and spectral and antibacterial studies of bivalent transition metal ion macrocyclic complexes

A new series of the macrocyclic complexes of type [M(C₁₈H₁₆N₄O₂)X₂], where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and X = Cl⁻, NO₃⁻, CH₃COO₋, has been synthesized by the condensation of succinyldihydrazide with benzil in the presence of bivalent metal ions. The complexes have been characterized with the aid of elemental analyses, conductance measurements, and electronic, NMR, and infrared spectral studies. On the basis of these studies, a six-coordinate distorted octahedral geometry in which two nitrogen and two carbonyl oxygen atoms are suitably placed for coordination toward metal ion has been proposed for all the complexes. The complexes were tested for their in vitro antibacterial activity. Some of the complexes showed remarkable antibacterial activity against some selected bacterial strains.     

Synthesis,structural, and biological studies of some bivalent metal ion complexes with the tridentate Schiff base ligand

New complexes of a Schiff base derived from 2-hydroxy-5-chloroacetophenone and glycine with Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and UO₂(VI) have been synthesized. The ligand and the complexes have been characterized on the basis of analytical data, electrical conductance, IR, ESR, and electronic spectra, magnetic susceptibility measurements and thermogravimetric analysis. The ligand acts as a dibasic tridentate (ONO) donor molecule in all the complexes except the Zn(II) complex, where it acts as a monobasic bidentate (OO) donor. Antibacterial activities of the ligand and its metal complexes have been determined by screening the compounds against various Gram(+) and Gram(−) bacterial strains. The solid state d.c. electrical conductivity of the ligand and its complexes has been measured over 313–398 K and the complexes were found to be of semiconducting nature. The article is published in the original.     

Triazoles as complexing agents: Synthesis and structural studies of some bivalent metal ion complexes with Bi- and tridentate ligands

Summary Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of 4-amino-5-mercapto-3-trifluoromethyl-s-triazole (AMTT) and 5-mercapto-4-salicylideneamino-3-trifluoromethyl-s-triazole (MSTT) have been synthesized and characterized on the basis of elemental analyses, magnetic measurements, infrared and electronic spectral data. The ligandsAMTT andMSTT were characterized by elemental analyses, infrared and¹H NMR spectral studies.AMTT, involving N and S as donor atoms, andMSTT, involving N, O and S as donor atoms, act as bi- and tridentate ligands, respectively. The geometry of the complexes has been assigned on the basis of magnetic and electronic spectral data. EPR parameters for copper (II) complexes have been calculated. Thermal stabilities of the complexes are also reported. Due to insolubility in water and common organic solvents and infusibility at higher temperatures, all the complexes are thought to be polymeric in nature.

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Triazole als Komplexierungs-Agentien: Synthese und Strukturuntersuchungen an einigen bivalenten Metallionenkomplexen mit zwei- und dreizähnigen Liganden

Zusammenfassung Es wurden Co(II)-, Ni(II)-, Cu(II)-, Zn(II)- und Cd(II)-Komplexe von 4-Amino-5-mercapto-3-trifluormethyl-s-triazol (AMTT) und 5-Mercapto-4-salizylidenamino-3-trifluormethyl-s-triazol (MSTT) hergestellt und mittels Elementaranalyse, magnetischen Messungen, Infrarot- und Elektronenspektroskopie charakterisiert. Die LigandenAMTT undMSTT wurden elementaranalytisch und spektroskopisch (IR und¹H-NMR) charakterisiert.AMT wirkt über die N-und S-Donoratome als zweizähniger Ligand,MSTT über N, O und S als dreizähniger Ligand. Die Geometrie der Komplexe wurde auf der Basis von magnetischen und elektronenspektroskopischen Daten zugeordnet. Für die Cu(II)-Komplexe wurden die EPR-Parameter berechnet. Die thermischen Stabilitäten der Komplexe wurde ebenfalls untersucht. Wegen ihrer Unlöslichkeit in Wasser und gängigen organischen Lösungsmitteln und der Unschmelzbarkeit bei höheren Temperaturen wird eine polymere Natur der Komplexe angenommen.

     

Synthesis and structural studies of new Mannich base ligands and their metal complexes

The new Mannich bases bis(1,4-diphenylthiosemicarbazide methyl) phosphinic acid H₃L¹ and bis(1,4-diphenylsemicarbazide methyl) phosphinic acid H₃L² were synthesised from the condensation of phosphinic acid, formaldehyde with 1,4-diphenyl thiosemicarbazide and 1,4-diphenylsemicarbazide, respectively. Monomeric complexes of these ligands, of general formulae K₂[Cr^III(L ⁿ )Cl₂], K₃[Mn^II(L ⁿ )Cl₂] and K[M(L ⁿ )] (M = Co(II), Ni(II), Cu(II), Zn(II) or Hg(II); n = 1, 2), are reported. The mode of bonding and overall geometry of the complexes were determined through physico-chemical and spectroscopic methods. These studies revealed octahedral geometries for the Cr(III), Mn(II) complexes, square planar for Co(II), Ni(II) and Cu(II) complexes and tetrahedral for the Zn(II) and Hg(II) complexes.     

Synthesis and structural studies of mixed-ligand complexes

Seven mixed-ligand complexes of cobalt(II), nickel(II) and copper(II) containing benzoylacetone andL-proline (HL¹), 2-pyrrolidone-5-carboxylic acid (HL²) orL-thioproline (HL³) were prepared and characterized by means of elemental analysis, IR, electronic spectra, magnetic moment measurements and molar conductance. Both HL¹ and HL² coordinate with these metal ions in a neutral zwitterionic form (-NH₂-CH-COO^–), whereas HL³ coordinates as a monobasic chelating agent (O/N). The continuous thermochromism of the nickel(II) complex of HL¹ (2) was attributed to a geometry change; it was investigated by DTA, TG, electronic spectra and X-ray powder diffraction techniques.     

Synthesis and structure of a Schiff base and its bivalent transition metal complexes

A Schiff base (HCSmz) was synthesized via (E)-cinnamaldehyde with S-methyl dithiocarbazate and six bivalent transition metal complexes [M(CSmz)₂] (M=Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, and Hg²⁺) were prepared. The complexes were characterized by elemental analyses, IR, ¹H NMR, and UV-Vis spectra, and the Ni(II) and Zn(II) complexes were also characterized by single crystal X-ray diffraction. After tautomerism of thiotone to thioenol and deprotonization of the thioenol, two ligands chelate the metal by two nitrogens of azomethine and two sulfurs of thioenol. Ni(CSmz)₂ crystallizes in the centrosymmetric space group P2₁ /n with a perfectly square planar trans-configuration with Ni located at the center of the square; crystal packing is stabilized by intra- and intermolecular C–H···S hydrogen bonds. Zn(CSmz)₂ is in the mirror-symmetric space group I4₁ /a in a distorted tetrahedral geometry with two equivalent Zn–N and Zn–S bonds; crystal packing is stabilized by intermolecular C–H···π hydrogen bonds.     

Thermal and other studies on bivalent metal selenltes

BaSeO₃·2·5H₂O(I), PbSeO₃· 2H₂O(II) and CdSeO₃·3.5H₂O(III) were prepared and analysed. Their hygroscopicity and solubility was investigated. These compounds have high thermal Stability, as shown by their TG and DTA data. IR spectra show multi-dentate coordination of selenite to cations, due to considerable splitting of the asymmetric v₃ and v₄ bands of SeO ₃ ^{2 –} in the 780-730 cm^–1 and 420-325 cm^–1 region.Tentative structures have been proposed involving bridging oxygen atoms.

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Zusammenfassung BaSeO₃-2.5H₂O(I), PbSeO₃ · 2H₂O(II) und CdSeO₃· 3.5H₂O(III) wurden hergestellt, analysiert sowie deren Hygroskopizität und Löslichkeit untersucht. TG- und DTA-Untersuchungen erweisen die hohe thermische Stabilität dieser Verbindungen. Die IR-Spektren zeigen mehrzählige Koordination von Selenit zu Kationen, was aus einer beträchtlichen Aufspaltung der antisymmetrischenv ₃ undv ₄ Banden von SeO ₃ ^{2 –} im Bereich 780-730cm^–1 bzw. 420-325 cm^–1 hervorgeht. Es wurden versuchsweise Strukturen mit überbrückenden Sauerstoffatomen vorgeschlagen.

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BaSeO₃· 2,5H₂O, PbSeO₃ · 2H₂O CdSeO₃ · 3,5H₂O . . - , v ₃ v ₄ SeO ₃ ² }- 780-730 420-325 ^–1. , .

     

Spectroscopic and structural studies on metal halide complexes of 4-vinylpyridine

Fourier transform infrared spectra (4000–400 cm⁻¹) are reported for metal(II) halide 4-vinlypridine complexes of the following stoichiometries: [MX₂(4-vipy]_n (n=4, M=Ni, X=Cl or Br; n=2, M=Cd, X=Cl, Br or I) and assignment are given for all the observed bands. These spectra were compared with X-ray powder diffraction patterns of complexes. It is shown that the proposed structures for these complexes derived from FTIR spectra are consistent with the X-ray powder diffraction measurements and the elemental analysis results. Coordination effect on 4-vinylpyridine has also been investigated.     

2,6-Diacetylpyridinesalicylaldazine complexes of bivalent metal ions

Summary 2,6-Diacetylpyridinesalicylaldazine (H₂daps) forms complexes [Ni(H₂daps)ClH₂O]Cl, [M(H₂daps)Cl₂H₂O] (M = Mn, Co, Cu or Zn) and [M(daps)(H₂O)₂] (M = Mn, Co, Ni, Cu or Zn) which have been characterized by elemental analyses, physicochemical methods, spectroscopy and X-ray powder diffraction.     

Synthesis and structural studies of some first row transition metal complexes of acetone isonicotinoyl hydrazone

Acetone isonicotinoyl hydrazone (AINH) has been found to form complexes of the types MCl₂·AINH·nEtOH and M(AINH-H)₂·nH₂O where M  Mn(II), Fe(II), Co(II), Ni(II), Cu(II) or Zn(II) and n  0, 1 or 2. Cu^ICl·AINH has also been prepared starting with Cu(II) chloride. All the complexes are found to be non-electrolytes in pyridine. Tentative structural conclusions are drawn for these complexes based upon electronic spectral and room-temperature magnetic measurements. IR spectral studies suggest that AINH functions as a bi- or tridentate ligand in the complexes of the former type and as a tridentate one in the latter type of complexes. The positions of the v(M-O) mode in the low frequency IR spectra of the complexes have been correlated with their overall stability constants, log K.     

Synthesis and structural studies of some copper-benzoate complexes

The reaction of CuCl₂·2H₂O with 3,5-diisopropylpyrazole (Pz^iPr2H) in the presence of sodium parafluorobenzoate (Na-p-FBz) resulted in the formation of an oxo-chloro-bridged tetranuclear complex [Cu₄(Pz^iPr2H)₄(μ-O)(μ-Cl)₆] 1, whereas the reaction of Cu(NO₃)₂·3H₂O with Pz^iPr2H in the presence of different benzoates gave [Cu(Pz^iPr2H)₂(μ-OCH₃)]₂(NO₃)₂ 2, [Cu(Pz^iPr2H)₃(NO₃)(p-ClBz)]·CH₃CN 3, [Cu(p-CH₃Bz)₂(Pz^iPr2H)]₂·2CH₃CN 4, [Cu(p-OCH₃Bz)₂(CH₃CN)]₂·4CH₃CN 5 and [Cu(p-CNBz)(CH₃CN)]₂ 6. Single-crystal X-ray diffraction studies confirmed these formulations. DNA binding studies for these complexes were performed by means of UV-visible absorption titration and viscosity measurements. Gel electrophoresis studies showed that hydroxyl radicals are involved in DNA cleavage in the presence of the complexes.     

Synthesis and structural studies of some first row transition metal complexes of acetone nicotinoyl hydrazone

Summary Acetone nicotinoyl hydrazone (ANII) complexes of the types M(ANH)Cl₂ · nEtOH and M(ANH-H)₂ H₂O (where M = Mn^II Fe^II, Co^II, Ni^II, Cu^II or Zn^II and n = 0,1 or 2) have been prepared and their structures studied by molar conductance, i.r. and electronic spectra, and room temperature magnetic measurements. All the complexes arc nonionic in a 0.001 M solution of formic acid. Magnetic and electronic spectral studies show that all the complexes are spin-free regular or distorted octahedra except Mn(ANH)Cl₂ and Co(ANH)CI₂ which are tetrahedral. The distorted octahedral geometry of Cu(ANH-H)₂ · H2O has also been confirmed from its sold state e.s.r spectrum at 77 K. From i.r. spectral studies, ANH has been found to act as a tridentate ligand in all the complexes except Mn(ANH)Cl₂ where it behaves as a bidentate ligand.     

Synthesis and structural characterization of a fully conjugated macrocyclic tetraaza(14)-membered Schiff base and its bivalent metal complexes

A novel 14-membered macrocyclic Schiff base derived from 3-cinnamalideneacetoacetanilide and o-phenylenediamine acts as a tetradentate and strongly conjugated ligand to form a cationic solid complex with CuCl₂/NiCl₂/CoCl₂/ZnCl₂. The ligand and the complexes were characterized by the usual spectral and analytical techniques. The main i.r. band of the macrocyclic Schiff base was compared to that of its metal complexes. The C=N bands are shifted to the lower wave number. The cyclic voltammogram of the copper complex shows that the macrocyclic ligand is able to stabilize the copper(III) oxidation state. The e.s.r. spectra of the copper complex in DMSO solution at room temperature and liquid N₂ temperature were recorded and their salient features thoroughly discussed. The antimicrobial screening tests were also recorded and gave good results in the presence of metal ions in the ligand system.     

Study on Semi-Glycinecresol Red complexes with bivalent metal ions

Semi-Glycinecresol Red (SGCR or H(3)SGCR) was purified by means of chromatography on cellulose and by cation-exchange. A potentiometric, spectrophotometric and ESR study on the complex formation equilibria of several bivalent metal ions with SGCR was performed. The acid-base and metal-ligand stoichiometries were determined, and the formation constants, lambda(max) and absorptivities of the visible-region absorption spectra of the corresponding proton and metal complexes were determined. The copper complexes were examined by ESR spectroscopy. Each metal ion was found to form the 1:1 and 1:2 (metal:ligand) complex species, MSGCR(-) and M(SGCR)(4-)(2), in alkaline solution. However, only Cu(II) was found to form the protonated complexes, CuHSGCR and Cu(HSGCR)(2-)(2), in weakly acidic media. SGCR is suitable as an indicator for Cu(II) in a weakly acidic solution and for Cu(II), Zn(II) and Pb(II) in alkaline solution.     

Synthesis and structural studies of some fluorescent group XII metal complexes with a terpyridine based ligand

Three 4′-(2-thienyl) substituted terpyridine (thioterpy) complexes of cadmium(II) and mercury(II) have been synthesized and fully characterized by spectroscopies. According to the crystallographic studies, the packing of these complexes was stabilized by several intermolecular interactions such as hydrogen bonding, C-H?π and π?π. Finally, the florescent properties of the prepared complexes have been investigated.     

Synthesis, spectroscopic, and structural studies on transition metal complexes involving homoleptic tripodal selenoether and telluroether coordination

The reaction of [MCl2(NCMe)2] (M = Pd or Pt) with 2 molar equiv of MeC(CH2ER)3 (E = Se, R = Me; E = Te, R = Me or Ph) and 2 molar equiv of TlPF6 affords the bis ligand complexes [M(MeC(CH2ER)3)2][PF6]2. The crystal structure of [Pt(MeC(CH2SeMe)3)2][PF6]2 (C16H36F12P2PtSe6, a = 12.272(10) A, b = 18.563(9) A, c = 15.285(7) A, beta = 113.18(3) degrees, monoclinic, P2(1)/n, Z = 4) confirms distorted square planar Se4 coordination at Pt(II), derived from two bidentate tripod selenoethers with the remaining arm not coordinated and directed away from the metal center. Solution NMR studies indicate that these species are fluxional and that the telluroether complexes are rather unstable in solution. The octahedral bis tripod complexes [Ru(MeC(CH2SMe)3)2][CF3-SO3]2 and [Ru(MeC(CH2TePh)3)2][CF3SO3]2 are obtained from [Ru(dmf)6][CF3SO3]3 and tripod ligand in EtOH solution. The thioether complex (C18H36F6O6RuS8, a = 8.658(3) A, b = 11.533(3) A, c = 8.659(2) A, alpha = 108.33(2) degrees, beta = 91.53(3) degrees, gamma = 106.01(2) degrees, triclinic, P1, Z = 1) is isostructural with its selenoether analogue, involving two facially coordinated trithioether ligands in the syn configuration. NMR spectroscopy confirms that this configuration is retained in solution for all of the bis tripod Ru(II) complexes. These low-spin d6 complexes show unusually high ligand field splittings. The hexaselenoether Rh(III) complex [Rh(MeC(CH2SeMe)3)2][PF6]3 was obtained by treatment of [Rh(H2O)6]3+ with 2 molar equiv of MeC(CH2SeMe)3 in aqueous MeOH in the presence of excess PF6- anion, while the iridium(III) analogue [Ir(MeC(CH2SeMe)3)2][PF6]3 was obtained via the reaction of the Ir(I) precursor [IrCl(C8H14)2]2 with the selenoether tripod in MeOH/aqueous HBF4. NMR studies reveal different invertomers in solution for both the Rh and Ir species. The Cu(I) complexes [Cu(MeC(CH2ER)3)2]PF6 were obtained from [Cu(NCMe)4]PF6 and tripod ligand in CH2Cl2 solution. The corresponding Ag(I) species [Ag(MeC(CH2TeR)3)2]CF3SO3 (R = Me or Ph) were obtained from Ag[CF3SO3] and tripod telluroether. In contrast, a similar reaction with 2 molar equiv of MeC(CH2SeMe)3 afforded only the 1:1 complex [Ag(MeC(CH2SeMe)3)]CF3SO3. The structure of this species (C9H18AgF3O3SSe3, a = 8.120(3) A, b = 15.374(3) A, c = 14.071(2) A, beta = 93.86(2) degrees, monoclinic, P2(1)/n, Z = 4) reveals a distorted trigonal planar geometry at Ag(I) derived from one bidentate selenoether and one monodentate selenoether. These units are then linked to adjacent Ag(I) ions to give a one-dimensional linear chain cation.