Mixed ligand complexes of coumarilic acid/nicotinamide with transition metal complexes

Coumarilate–nicotinamide complexes of Co^II and Zn^II were synthesized and investigated by elemental analysis, magnetic susceptibility, solid state UV–Vis, direct injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA, and crystal X-ray diffraction methods. It was obtained that both complex structures contain 2 mol aqua ligands, 2 mol coumarilate (CCA^?) and 2 mol nicotinamide (NA) ligands per formula unit. The CCA^? and NA ligands were bonded to metal cations as monodentate through acidic oxygen and nitrogen of pyridine ring, respectively. Thermal decomposition of each complex starts with dehydration and continue removing of 1 mol NA ligand. The thermal dehydration of the complexes takes place in one or two steps. The decomposition mechanism and thermal stability of the investigated complexes are interpreted in terms of their structures. The final decomposition products are found to be metal oxides.     

Mixed ligand palladium(II) and platinum(II) complexes of tertiary diphosphines and benz-1,3-imidazoline-2-thione,benz-1,3-oxazoline-2-thione or benz-1,3-thiazoline-2-thione

Palladium(II) and platinum(II) complexes containing the mixed ligands tertiary diphosphines Ph₂P(CH₂) _n PPh₂, (n = 1–4) and benz-1,3-imidazoline-2-thione, benz-1,3-oxazoline-2-thione or benz-1,3-thiazoline-2-thione have been prepared and characterized by elemental analysis, magnetic susceptibility, molar conductance and i.r. spectral data. ³¹P–{¹H}-n.m.r. data have been applied to characterize the produced linkage isomers.     

Mixed ligand gold(I) complexes with phosphines and selenourea

A series of mixed ligand Au^I complexes with selenourea (Seu) and various phosphines, [R₃PAuSeu]Cl, have been prepared and characterized by elemental analysis, i.r. and n.m.r. methods. A decrease in the i.r. frequency of the C=Se mode of Seu upon complexation is indicative of Au^I binding via a selenone group. An upfield shift in the ¹³C-n.m.r. for the C=Se resonance of Seu, and downfield shifts in ³¹P-n.m.r., for the R₃P moiety are consistent with selenium coordination to Au^I.     

Radius-dependent assembly of complexes with the rigid unsymmetric ligand 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione: Syntheses,structures and luminescence properties

The free ligand, 5-(2-pyridyl)-1,3,4-oxadiazole-2-thione (1, HL5), has been synthesized and characterized; its three new functional d¹⁰ transition-metal complexes, [Zn(L5)₂(H₂O)₂] (2), [Cd(L5)₂]_n (3) and [Hg₂(L5)₄] (4), have been successfully obtained by a diffusion synthetic method and characterized by single-crystal X-ray diffraction, infrared spectroscopy, elemental analysis, thermogravimetric analysis, and photoluminescence. On the basis of the X-ray analyses, the radii of the metal ions are found to play an important role in determining the structures. The radii and nature of the metal ions can impart their influence on the coordination geometry of the d¹⁰ transition-metal atoms, which seems to be the main factor controlling the structures and luminescent properties of the reaction products in this system.     

Mixed ligand complexes involving aminoacid dithiocarbamates,substituted phosphines and nickel(II)

Mixed ligand complexes involving four aminoacid dithiocarbamates (RRdtc=glydtc^– (R=H; R=H), methdtc^– (R=H; R=C₃H₇S), sardtc^– (R=Me; R=H), trydtc^– (R=H; R=C₉H₈N), substituted phosphines [PPh₃, Ph₂PCH₂CH₂PPh₂(dppe)] and nickel(II) are reported. All are diamagnetic. Thermal analyses of the complexes are in keeping with the proposed formulae. Thermal decomposition of the dithiocarbamate moiety proceeds through the formation of Ni(SCN)₂. PPh₃ and dppe are lost in the initial decomposition stages.     

A 2-D nickel coordination polymer with an unsymmetric ligand, 5-(3-pyridyl)-1,3,4-oxadiazole-2-thione

A new nickel coordination polymer was obtained from an unsymmetric building block 5-(3-pyridyl)-1,3,4-oxadiazole-2-thione (HL6) and Ni(NO₃)₂ · 6H₂O-afforded [Ni(L6)₂(H₂O)₂] _n (1) with a (4,4) network. Complex 1 exhibits moderate antimicrobial activity against Bacillus subtilis ATCC 6633 and Candida albicans ATCC 90028. Thermogravimetric data and magnetic moments for 1 have been investigated.     

Synthesis,structures and characterization of two new supramolecular coordination complexes with the ambidentate ligand 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot)

Two new coordination supramolecular complexes based on a versatile and unsymmetrical 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) and Mn^II and Ni^II have been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Reaction of MnCl₂?· 4H₂O with Hpot afforded a neutral mononuclear complex [Mn(pot)₂(H₂O)₄]?·?2H₂O (1), which exhibits a three-dimensional (3-D) supramolecule through versatile intermolecular O–H?···?X (X=O, N and S) hydrogen bond interactions. When using NiCl₂?·?6H₂O instead of MnCl₂?· 4H₂O under similar reaction conditions, a neutral mononuclear complex [Ni(pot)₂(H₂O)₄] (2) is also obtained, which does not exhibit intermolecular hydrogen bonds and π–π stacking interactions. It is very interesting that the pot anion exhibits different coordination modes in complexes 1 and 2. The IR spectra and the TGA for 1 and 2 have been investigated and discussed in detail.     

Antituberculosis,antifungal and thermal activity of mixed ligand transition metal complexes

Mixed‐ligand complexes of the type [M(CQ)(Ph)(OH)(H₂O)], where M = Cu(II), Ni(II), Co(II) and Mn(II), have been investigated. Furthermore, there has been some additional work investigating the effect of metal ions on biological activity. Aiming to obtain novel transition metal complexes that exhibit biological activity, we have synthesized mixed ligand complexes using clioquinol (5‐chloro‐7‐iodo‐8‐hydroxyquinoline) and 1,10‐phenanthroline as ligands. The compounds were characterized using IR, FAB mass spectroscopy, elemental analyses, electronic spectra, magnetic measurements and gravimetric analyses. The kinetic parameters such as order of reaction, the energy of activation, the pre‐exponential factor, activation entropy, activation enthalpy and free energy of activation have been reported. The complexes show antituberculosis and antifungal (minimal inhibitory concentration) activities. Copyright © 2010 John Wiley & Sons, Ltd.     

3,4-Dicyano-5-aminopyrazole complexes of anhydrous divalent transition metal chlorides and their triphenylphosphine derivatives

Summary 3,4-Dicyano-5-aminopyrazole, H3,4(CN)₂5NH₂pz (L) reacts either with anhydrous MCl₂ or with [M(PPh₃)₂Cl₂] to yield ML₄Cl₂ complexes (M = Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd or Hg), whose monomeric and covalent natures have been confirmed by their solubility in most non-polar solvents and their low electrical conductivities. The bonding mode of substituted pyrazole is inferred from the position of the (C-N) band in the i.r. spectra. The electronic spectra and the magnetic moments of these compounds were recorded.     

Metal-assisted transformation of N-benzoyldithiocarbazate to 5-phenyl-1,3,4-oxadiazole-2-thiol in the presence of ethylenediamine,and its first row transition metal complexes

The reaction of metal complexes of the type [M(HL)Cl] or [M(HL)₂] [where M = Cu(II), Ni(II), Mn(II), Co(II) and Zn(II) and H₂L = N-benzoyldithiocarbazate] with an excess of ethylenediamine (en) in CHCl₃–MeOH medium leads to ring closure by desulfurisation to yield unique mixed-ligand complexes 1–4, [Cu(en)₂](pot)₂(pot = 5-phenyl-1,3,4-oxadiazole-2-thiol), [M(en)₂(pot)₂] [M = Ni(II), Mn(II)] and [Zn(en)(pot)₂]. The metal complexes have been characterized by various physicochemical methods. The molecular structure of [Cu(en)₂](pot)₂ has been determined by a single crystal X-ray diffraction study. In the centrosymmetric unit of [Cu(en)₂](pot)_2, the metal ion has a square planar arrangement of four symmetry related N-atoms of two en groups and is ionically bonded to two pot anions. Weak interaction studies on the complex reveal the presence of a hydrogen-bonded network in the molecule involving non-coordinating donor atoms of the pot anion with en resulting in the formation of an extended three-dimensional network. The arrangement of the [Cu(en)₂]²⁺ units, at a dihedral angle of 49.43° to pot⁻, provides a network of intermingled chains leading to a π–π stacked 3-dimensional framework.     

Tetracarbonyl group 6 complexes containing secondary and tertiary phosphines

The mixed ligand tetracarbonyl derivatives, cis-M(CO)₄(PPh₂H)(PPh₃) (M  Cr, Mo, W) and cis-W(CO)₄(PPh₂H)(L) (L  PEt₃, PEt₂Ph, PEtPh₂) have been prepared from the reaction of M(CO)₅PPh₂H with L in THF in the presence of potassium t-butoxide. These reactions are accompanied in most instances by the formation of [W(CO)₅PPh₂]⁻, [(OC)₅M(μ-PPh₂)M(CO)₅]⁻, [(OC)₅M(μ-PPh₂)-M(CO)₄(PPh₂H)]⁻, [(OC)₄M(μ-PPh₂)₂M(CO)₄]²⁻, (OC)₄M(μ-PPh₂)₂M(CO)₄, and cis-M(CO)₄(PPh₂H)₂.     

DFT characterization of 1-acetylpiperazinyl-dithiocarbamate ligand and its transition metal complexes

Employing DFT and handling the solvent effects with the PCM model, the 1-acetylpiperazinyldithiocarbamate acpdtc ligand and its M(acpdtc)₂ complexes, where M is Mn(II), Fe(II), Co(II), Ni(II) and Cu(II), are characterized computationally. The obtained results suggest that the piperazine ring adopts chair conformation in all the studied species. In the gas and solution phases, the chair form of the ligand is dominant. For the Mn, Fe and Co complexes the tetrahedral structure is more stable than the square form in the gas and solution phases. However, the Ni and Cu complexes adopt the square form, in which the complex has the inversion center. The calculated vibrational frequencies are in agreement with the experimental ones, confirming the suitability of the optimized geometries of the compounds. Atomic charges, electron distribution of the frontier orbitals, and stabilizing electron transfers are determined by the NBO analysis.     

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.     

Synthesis of 5-(4,6-dimethyl-2-pyrimidinyl)-1,3,4-oxadiazole-2-thione and its alkylation,aminomethylation, and acylation

The reaction of the hydrazide of 4,6-dimethyl-2-pyrimidinecarboxylic acid with potassium ethylxnthate gave 5-(4,6-dimethyl-2-pyrimidinyl)-1,3,4-oxadiazole-2-thione. The alkylation of this product in an alkaline medium proceeds at the sulfur atom, while the aminomethylation and acylation proceed at the nitrogen atom. The major criterion for the structure of the S- and N-derivatives is the chemical shift of C₍₂₎ in the 1,3,4-oxadiazole ring in the ¹³C NMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 700–705, May, 1993.     

5-(2-芳氧甲基苯并咪唑-1一亚甲基)-1,3,4-噁二唑-2-硫酮的合成、晶体结构及生物活性研究

以2-芳氧甲基苯并咪唑-1-乙酰肼类化合物为原料在微波辐射条件下合成了10种尚未见文献报道的5-(2-芳氧甲基苯并咪唑-1-亚甲基)-1,3,4-噁二唑-2-硫酮衍生物,化合物结构经IR 1H NMR,13C NMR和元素分析进行了表征,6a晶体结构表明,该化合物通过分子间氢键自组装成了沿b轴无限延伸的一维链状超分子结构,属于单斜晶系,P21/c空间群,a=11.5484(13)A,6=16.5319(19)A,c=11.3595(14)A,β=108.755(2)°,Z=2,V=2053.6(4)A3,Dx=1.328 g/cm3,F(000)=860,μ=0.19 mm-1,R=0.060,wR=0.196.初步生物活性试验结果表明该系列部分化合物对油菜幼苗的生长具有明显的生长调节作用,并对枯草杆菌具有一定的抑制作用.     

5-(4,6-Diphenyl-2-pyrimidinyl)-1,3,4-oxadiazole-2-thione with Some C-Electrophiles and N-Nucleophiles

5-(4,6-Diphenyl-2-pyrimidinyl)-1,3,4-oxadiazole-2-thione reacted with haloalkanes or their derivatives containing side chain oxo group to give S-alkylated compounds. Aminomethylation and acylation of the thione yielded N₍₃₎-derivatives. Treatment of the title compound with hydrazine hydrate in butanol resulted in 4-amino-5-(4,6-diphenyl-2-pyrimidinyl)-1,2,4-triazole-3-thione via a recyclization reaction. Reaction of the title compound with hydrazine hydrate or phenylhydrazine in dioxane led to formation of the corresponding thiocarbohydrazides. The latter in the presence of a base were cyclized to 4-amino-1,2,4-triazole-3-thiones.     

Formylferrocene 5–phenyloxazole-2–carbonylhydrazone bivalent transition metal complexes

Bivalent transition metal complexes of the new ligand formylferrocene 5–phenyloxazole-2–carbonylhydrazone (HFfoh) have been prepared and characterized by elemental analyses, molar conductivities, i.r., n.m.r., u.v. spectra and thermal analyses. In all the complexes, the ligand coordinates to the metal ion via the azomethine nitrogen and enolic oxygen as a bidentate donor to give [MOAc(Ffoh)]nH2O, where OAc− also acts as a bidentate ligand. This revised version was published online in June 2006 with corrections to the Cover Date.