Synthesis and characterization of complexes of lanthanide nitrates with N,N′-dinaphthyl-N,N′-diphenyl-3,6-dioxaoctanediamide

Solid complexes of lighter lanthanide nitrates with N,N′-dinaphthyl-N,N′-diphenyl-3,6-dioxaoctanediamide (DDD), Ln(NO₃)₃(DDD) (Ln = La---Nd, Sm) have been prepared in non-aqueous media. These complexes have been characterized by elemental analysis, conductivity measurements, IR spectra, electronic spectra and TG-DTA techniques. In all the complexes, DDD and NO₃⁻ are coordinated to the lanthanide ions as tetradentate and bidentate ligands, respectively. The differences in the IR and electronic spectra between these complexes and lanthanide nitrate complexes with N,N,N′,N′-tetraphenyl-3,6-dioxaoctanediamide (TDD) are discussed.     

Synthesis,characterization, thermogravimetry,and structural study of uranium complexes derived from dibasic S-alkylated thiosemicarbazone ligands

Two pentagonal bipyramidal complexes, ethanol-(S-ethyl-N¹,N⁴-bis(3-methoxy-2-hydroxybenzaldehyde)-isothiosemicarbazide-N,N′,O,O′)-dioxidouranium(VI) (1) and ethanol-(S-ethyl-N¹-(2-hydroxyacetophenone)-N⁴-(5-bromo-2-hydroxybenzaldehyde)-isothiosemicarbazide-N,N′,O,O′)-dioxidouranium(VI) (2), have been prepared and characterized. Their structures have been determined by X-ray crystallography, and the structural parameters are discussed with those observed in related complexes. Electronic absorption, proton magnetic resonance, and FT-IR spectra have been recorded and analyzed. In both complexes, the U(VI) centers are surrounded by N₂O₂ donor ligands, two oxido groups, and one ethanol in a distorted pentagonal bipyramid. The thermal stability of the new complexes has also been determined.     

Synthesis,Crystal Structure and Properties of Two Macrocyclic Dinuclear Complexes

Two macrocyclic dinuclear complexes, [Cu₂L¹](PF₆)₂ and [Cu₂L²](ClO₄)₂, were synthesized by cyclo-condensation between N,N′-bis(3-formyl-5-methylsalicylidene)ethylenediimine or N,N′- bis(3-formyl-5-n-butylsalicylidene)ethylenediimine and ethylenediamine in the presence of Cu²⁺ ions. The crystal structures of the complexes were studied. The variable-temperature magnetic susceptibilities and cyclic voltammograms of the complexes were measured. The magnetic and electrochemical properties of the complexes were discussed. The results show that the complexes display very strong antiferromagnetic exchanges and that all copper(II) complexes undergo a one-electron transfer process.     

Synthesis, Crystal Structure and Properties of Polyamine Copper(II) Complexes

Two polyamine copper(II) complexes were synthesized by the reaction between N,N,N′,N′-tetrakis(2′-aminoethyl)propane-1,2-diamine hexahydrochloride and copper(II) perchlorate under almost the same conditions except for reaction temperature. The crystal structures of two complexes were determined by X-ray diffraction techniques, which shows that one of the complexes is unexpected and is a double chlorine or chloride-bridged dinuclear copper(II) complex formed by two diethylenetriamines, and another is a pentadentate mononuclear copper(II) complex composed of homo-protonated N,N,N′,N′-tetrakis(2′-aminoethyl)propane-1,2-diamine. The mechanism of the reaction leading to form the unexpected complex was discussed. The UV-visible spectra and cyclic voltammogram of the complexes were measured.     

Synthesis,Structure and Cytotoxicity of N,N and N,O-Coordinated RuII Complexes of 3-Aminobenzoate Schiff Bases against Triple-negative Breast Cancer

Half-sandwich Ru^II complexes, [(YZ)Ru^II(η⁶-arene)(X)]+, (YZ=chelating bidentate ligand, X=halide), with N,N and N,O coordination ( 1 – 9 ) show significant antiproliferative activity against the metastatic triple-negative breast carcinoma (MDA-MB-231). 3-aminobenzoic acid or its methyl ester is used in all the ligands while varying the aldehyde for N,N and N,O coordination. In the N,N coordinated complex the coordinated halide(X) is varied for enhancing stability in solution (X=Cl, I). Rapid aquation and halide exchange of the pyridine analogues, 2 and 3 , in solution are a major bane towards their antiproliferative activity. Presence of free −COOH group ( 1 and 4) make complexes hydrophilic and reduces toxicity. The imidazolyl 3-aminobenzoate based N,N coordinated 5 and 6 display better solution stability and efficient antiproliferative activity (IC₅₀ ca. 2.3–2.5 μM) compared to the pyridine based 2 and 3 (IC₅₀>100 μM) or the N,O coordinated complexes ( 7 – 9 ) (IC₅₀ ca. 7–10 μM). The iodido coordinated, 6 , is resistant towards aquation and halide exchange. The N,O coordinated 7 – 9 underwent instantaneous aquation at pH 7.4 generating monoaquated complexes stable for at least 6 h. Complexes 5 and 6 , bind to 9-ethylguanine (9-EtG) showing propensity to interact with DNA bases. The complexes may kill via apoptosis as displayed from the study of 8 . The change in coordination mode and the aldehyde affected the solution stability, antiproliferative activity and mechanistic pathways. The N,N coordinated ( 5 and 6 ) exhibit arrest in the G2/M phase while the N,O coordinated 8 showed arrest in the G0/G1 phase.     

Co(III) N,N′-diarylformamidine dithiocarbamate complexes: Synthesis,characterization, crystal structures and biological studies

Three symmetric N,N-diarylformamidine dithiocarbamates, N,N′-bis(2,6-dimethylphenyl)formamidine dithiocarbamate (DTL1), N,N′-bis(2,6-disopropylphenyl)formamidine dithiocarbamate (DTL2) and N,N′-dimesitylformamidine dithiocarbamate (DTL3), and three unsymmetric ones, N′-(2,6-dichlorophenyl-N-(2,6-dimethylphenyl)formamidine dithiocarbamate (DTL4), N′-(2,6-dichlorophenyl)-N-(2,6-diisopropylphenyl)formamidine dithiocarbamate (DTL5) and N′-(2,6-dichlorophenyl)-N-mesitylformamidine dithiocarbamate (DLT6), were reacted with chloridocobalt(III) in water to give Co-(DTL1)₃ ( 1 ), Co-(DTL2)₃ ( 2 ), Co-(DTL3)₃ ( 3 ), Co-(DTL4)₃ ( 4 ), Co-(DTL5)₃ ( 5 ) and Co-(DTL6)₃ ( 6 ). All the dithiocarbamates and complexes were characterized using ¹H NMR, ¹³C NMR, Fourier transform infrared, UV–visible and mass spectra and the purity confirmed by elemental analysis. In addition, crystal structures of complexes 1 , 2 , 4 and 5 were determined, confirming the formation of mononuclear species in which the Co(III) centers coordinated to six sulfur atoms from three dithiocarbamate ligands resulting in distorted octahedral geometries. All complexes showed moderate to good antibacterial activities against Gram-negative bacteria Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae and Pseudomonas aeruginosa even at low concentrations. None of the six were active against Gram-positive bacterium methicillin-resistant Staphylococcus aureus and only active against S. aureus at high concentrations. Complexes 5 and 6 were found to be more active than ciprofloxacin against S. typhimurium, E. coli, P. aeruginosa and K. pneumoniae and complexes with chloro-substituted ligands generally had enhanced activities. Antioxidant activities of the dithiocarbamate salts and their Co(III) complexes were also investigated using DPPH assay and the complexes were found to be more efficient. Complex 2 with an IC₅₀ value of 2.84 × 10⁻⁴ mM displayed the highest activity of all compounds tested, even outdoing ascorbic acid. The radical scavenging ability of the complexes followed the order 2 > 1 > ascorbic acid > 3 > 4 > 6 > 5 .     

Complexation of N-alkyl(aryl)- and N,N-dialkylcarbamoylmethylphosphine oxides with the f-elements

Complexation of N-alkyl(aryl)carbamoylmethylphosphine oxides (CMPO) and their N, N-dialkyl analogs in neutral media was studied. N-Alkyl derivatives react with praseodymium and europium nitrates both in solution and in the individual state to give 1: 2 and 1: 3 complexes, depending on the ratio of the starting reagents; for N-aryl amides, 1: 3 complexes were obtained only. With the uranyl cation, both N-alkyl and N,N-dialkyl derivatives of CMPO form various 1: 1 complexes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1856–1862, September, 2008.     

New acyclic Schiff-base copper(II) complexes and their electrochemical,catalytic, and antimicrobial studies

A new series of acyclic mononuclear copper(II) complexes have been prepared by Schiff-base condensation derived from 5-methylsalicylaldehyde, diethylenetriamine, tris(2-aminoethyl) amine, triethylenetetramine, N,N-bis(3-aminopropyl)ethylene diamine, N,N-bis(aminopropyl) piperazine, and copper perchlorate. All the complexes were characterized by elemental and spectral analyses. Electronic spectra of the complexes show a d–d transition in the range 500–800?nm, electrochemical studies of the complexes show irreversible one-electron-reduction process around ?1.10 to ?1.60?V. The reduction potential of the mononuclear copper(II) complexes shifts toward anodic direction upon increasing the chain length of the imine compartment. ESR spectra of the mononuclear copper(II) complexes show four lines, characteristic of square-planar geometry, with nuclear hyperfine spin 3/2. The copper(II) complexes show a normal room temperature magnetic moment value μ _eff?=?1.72–1.76?BM, close to the spin-only value of 1.73?BM. Electrochemical and catalytic studies of the complexes were compared on the basis of increasing the chain length of the imine compartment. All the complexes were screened for antifungal and antibacterial activities.     

Synthesis,characterization, and thermal decomposition of fluorinated salicylaldehyde Schiff base derivatives (salen) and their complexes with copper(II)

Trifluoromethoxy functionalized copper(II) Schiff base complexes N,N′-bis(5-trifluoromethoxysalicylaldehyde)cyclohexanediiminatodiaquacopper(II) and N,N′-bis(5-trifluoromethoxysalicylaldehyde)phenylenediiminatocopper(II) were synthesized and characterized. Thermal decompositions of the synthesized complexes were studied by thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathways. Three similar decomposition steps occurred for the two copper complexes. Mass losses and evolved gasses were characterized by TG/DTA-MS. Kinetic parameters were calculated and the results showed that the values obtained are comparable.     

Complexes of Uranyl Nitrate with 2,6‐Pyridinedicarboxamides: Synthesis,Crystal Structure,and DFT Study

Two complexes of uranyl nitrate with N,N,N′,N′‐tetrabutyl‐2,6‐pyridinedicarboxamide (TBuDPA) and N,N′‐diethyl‐N,N′‐diphenyl‐2,6‐pyridinedicarboxamide (EtPhDPA) were synthesized and studied. The complex of tetraalkyl‐2,6‐pyridinedicarboxamide with metal nitrate was synthesized for the first time. XRD analysis revealed the different type of complexation: a 1:1 metal:ligand complex for EtPhDPA and complex with polymeric structure for TBuDPA. The quantum chemical calculations (DFT) confirm that both ligands form the most stable complexes that match the minimal values pre‐organization energy of the ligands.     

The chemical and antifungal properties of the copper(II) complexes of 2-acetylpyrazine4 N-methyl-,4 N-dimethyl-, and 3-hexamethyleneiminylthiosemicarbazone

Summary Copper(II) complexes of 2-acetylpyrazine² N-methyl-,⁴ N-dimethyl- and 3-hexamethyleneiminylthiosemicarbazone have been prepared and characterized. Inhibition of the growth ofAspergillus niger andPaecilomyces bariotii by both the thiosemicarbazones and their copper(II) complexes is included.     

Zine Complexes of Cysteine,Histidine, and Derivatives Thereof: Potentiometric determination of their compositions and stabilities

The stabilities of Zn complexes of cysteine and histidine have been determined together with those with those of three derivatives of each n which one of their three donor functions (carboxyl, amino, and mercapto and imidazole, respectively) has been blocked. Using potentionmetric titrations of aqueous solutions, the 1:1 and 1:2 complexes of all for cysteine- and all four histidine-derived ligands are observed among te various species present (ligands, 1:1 and 1:2 complexes, and protonatd derivatives thereof). All cysteine-derived complexes are more stable than the corresponding histidine-derived complexes by 1–2 orders of magnitude for the 1:1 composition and by 1–6 order of magnitude for the 1:2 composition. For the cysteine series, the sequence of stabilities is cysteine > cysteine ethyl ester ? N(α)-acetylcysteine ? SMethylcysteine. For the histidine series, the corresponding sequence is histidine > histidine methyl ester > N,N (imidazole)-dimethylhistidine > N(α)-acetylhistidine. The order of stabilities can be explained by the relative strengths of the Zn–S vs. Zn–N coordination, y charge effects, and by chelate ring sizes.     

Preparation,spectral characterization,in vitro antitumor and thermal studies of new platinum(IV) and palladium(II) thiohydrazone complexes

Pt^IV and Pd^II complexes [Pt(L)₂Cl₂] and [Pd(HL)Cl₂] [HL = salicyclaldehyde morpholine N-thiohydrazone (HL¹), benzaldehyde morpholine N-thiohydrazone (HL²), acetophenone morpholine N-thiohydrazone (HL³), p-methylacetophenone morpholine N-thiohydrazone (HL⁴), cinnamaldehyde morpholine N-thiohydrazone (HL⁵), cyclohexanone morpholine N-thiohydrazone (HL⁶), benzaldehyde aniline N-thiohydrazone (HL⁷), benzaldehyde N-(methyl, cyclohexyl)-thiohydrazone (HL⁸) and benzaldehyde N-(ethyl, cyclohexyl)-thiohydrazone (HL⁹)] were prepared in MeOH and characterized by elemental analysis, i.r., electronic, ¹H-n.m.r. and ¹³C-n.m.r. spectral data. For some of the complexes cyclic voltammetric and thermal studies were carried out. The in vitro antitumor activity of some complexes was measured.     

Gold(III) complexes with imidazole,benzoxazole, purine and pyrimidine derivatives

Summary The synthesis and characterization of Au^III complexes with several heterocyclic ligands are reported. The compounds have general formula [AuX₃(L)], where L =N-methylimidazole (N-MeIz),N-ethylimidazole (N-EtIz),N-propylimidazole (N-PrIz), benzoxazole (BO), 2-methylbenzoxazole (2-MeBO), 2,5-dimethylbenzoxazole (2,5-diMeBO), 2-amino-pyrimidine (2-APm), 4(6) -hydroxy-pyrimidine [4(6)-hydrPm] or hypoxanthine (Hypox) and X = Cl or Br. Elemental analysis, conductivity measurements and spectral studies were used for the characterization of the complexes. A square-planar geometry withN-bonded heterocyclic ligands is suggested.     

Synthesis and characterization of group 12 complexes of N,N-methyl phenyl-N,N-butyl phenyl dithiocarbamate

Zn(II), Cd(II), and Hg(II) complexes of N-methyl-N-phenyl dithiocarbamate (L¹) and N-butyl-N-phenyl dithiocarbamate (L²) formulated as ML¹L² have been synthesized and characterized by elemental analysis, FT–IR, ¹H- and ¹³C-NMR spectroscopic techniques. Single-crystal X-ray structures of the Zn(II) and Hg(II) complexes are also reported. X-ray crystal structures revealed that in the zinc(II) complex, the dithiocarbamate is chelating and bridging, forming eight-member rings, while the Hg complex is monomeric with bidentate dithiocarbamate. In both complexes, the metals are in distorted tetrahedral geometry and the methyl and butyl groups of the dithiocarbamates exhibit compositional disorder between two positions.     

Copper(II) complexes of 2-formyl-, 2-acetyl- and 2-benzoyl-pyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxy-phenyl- and N(4)-p-nitrophenylthiosemicarbazones

Summary Cu^II complexes of 2-formyl-, 2-acetyl- and 2-benzoylpyridine N(4)-phenyl-, N(4)-o-methoxyphenyl-, N(4)-p-methoxyphenyl- and N(4)-p-nitrophenyltniosemicarbazones, coordinated either as neutral or monoanionic ligands, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as ¹H-and ¹³C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. However, some of these thiosemicarbazones possess significant activity against a number of tumour cell strains.     

Synthesis,Structure, and Fungicidal Activity of Organotin Dithiocarbamates Derived from Pyridinamines and Aryl Diamines

A reaction of N‐benzylpyridinamines with n‐BuLi, followed by a reaction with CS₂ and R₃SnCl or R₂SnCl₂ (R = n‐Bu, PhCH₂, or Ph) gave a series of mononuclear organotin dithiocarbamates. A similar reaction of N,N'‐bis(benzyl)‐1,3‐benzenediamine and N,N'‐bis(benzyl)‐2,6‐pyridinediamine afforded dinuclear and macrocyclic organotin dithiocarbamates. All of these complexes were characterized by elemental analysis, IR, and multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn). Their structures have been confirmed by the X‐ray single crystal diffraction analysis, suggesting the dithiocarbamate groups acted as anisobidentate chelating ligands in these complexes. The primary fungicidal activity of these complexes was tested in vitro, showing that most complexes displayed good antifungal activity to Sclerotinia sclerotiorum.     

13C NMR spectral data for some N,N-dialkylbenzylamines and their cyclopalladated complexes

¹³C NMR data for some N,N-dialkylbenzylamines and their chloro-(N,N-dialkylbenzylamine-6,C,N)-tri-phenylphosphinepalladium(II) complexes are presented and simple shift parameters defined.     

Neutral Pentacoordinate Silicon(IV) Complexes with a Tridentate Dianionic O,N,O or N,N,O Ligand,an Anionic PhX Ligand (X = O,S, Se), and a Phenyl Group: Synthesis and Structural Characterization in the Solid State and in Solution

A series of neutral pentacoordinate silicon(IV) complexes with a SiO₃NC, SiO₂SNC, SiO₂SeNC, SiO₂N₂C, SiOSN₂C, or SiOSeN₂C skeleton was synthesized and structurally characterized by multinuclear NMR spectroscopy in the solid state and in solution and by single‐crystal X‐ray diffraction. The compounds studied contain a tridentate dianionic O,N,O or N,N,O ligand, an anionic PhX ligand (X = O, S, Se), and a phenyl group. The structures, NMR spectroscopic parameters, and chemical properties of these silicon(IV) complexes were compared with those of related compounds that contain a tridentate dianionic S,N,O ligand instead of the O,N,O or N,N,O ligand.     

Aluminum complexes of sterically hindered tetradentate Schiff bases: Synthesis, structure, and reactivity toward -caprolactone

The sterically hindered Schiff bases tbmSalenH₂ [tbmSalen = N,N′-1,2-ethylenebis(3-tert-butyl-5-methylsalicylideneimine)] and tbmSalcenH₂ [tbmSalcen = N,N′-trans-1,2-cyclohexanediyl-bis(3-tert-butyl-5-methylsalicylideneimine)] afforded a series of aluminum complexes of the general formulae [Al(tbmSalen)X] and [Al(tbmSalcen)X] (X = Cl, Me, Et). The molecular structure of [Al(tbmSalcen)Cl] was determined by single-crystal X-ray structural analysis which revealed a five-coordinate aluminum center with a distorted square pyramidal geometry. The alkyl complexes were found to oligomerize -caprolactone.