Boron Cluster Anions [BnHn]2– (n = 10, 12) in Reactions of Iron(II) and Iron(III) Complexation with 2, 2′‐Bipyridyl and 1, 10‐Phenanthroline

Complexation of Fe^II and Fe^III with azaheterocyclic ligands L (L = phen or bipy) were studied in the presence and in the absence of boron cluster anions [B_nH_n]^2– (n = 10, 12). The reactions were carried out in air at room temperature in organic solvents and/or water. In all the solvents used, well known [FeL₃]An (An = 2Cl^– or SO₄^2–) ferrous complexes were formed from Fe^II salts. Composition of ferric complexes with L ligands depends on the nature of solvent: either dinuclear oxo‐iron(III) chlorides [L₂ClFe^III–O–Fe^IIIL₂Cl]Cl₂ or ferric ferrates(III) [Fe^IIIL₂Cl₂][Fe^IIICl₄], or [Fe^IIIL₂Cl₂][Fe^IIICl₄L] were isolated from Fe^III salts. Introduction of the closo‐borate anions to a Fe³⁺(or Fe²⁺)/L/solv. mixture stabilizes ferrous cationic complexes [FeL₃]²⁺ in all the solvents used: only ferrous [FeL₃][B_nH_n] (n = 10, 12) complexes were isolated from all the reaction mixtures in the presence of boron cluster anions.     

Complexes of divalent transition metal chlorides with the tetradentate Schiff base ligand 1,2-bis(2′-pyridylmethyleneimino)-benzene

Summary Transition metal(II) chloro complexes of the new Schiff base ligand 1,2-bis(2-pyridylmethyleneimino)benzene (L), derived from 2-pyridinecarboxaldehyde and 1,2-phenylenediamine, were prepared. Compounds of [MnLCl₂]-H₂O, [CoLCl₂]·2H₂O, [NiLCl₂] and [Zn₃L₂Cl₄]Cl₂ were prepared. Details are given of the formation of the complex [Cu(L·EtOH)Cl₂], in which one molecule of EtOH adds across only one of the Schiff base {ie531-01} groups to give the coordinated ligand L·EtOH. The rationalization of this type of reaction by considering the steric requirements of the ligand is given. The complexes were characterized by elemental analyses, conductivity measurements, thermal techniques, mass spectra, magnetic susceptibilities and spectroscopic (i.r., ligand field, e.s.r., ¹H n.m.r.) studies. The nitrogen donor atoms of the tetradentate ligands L and L·EtOH are assumed to adopt an essentially planar arrangement about manganese(II), cobalt(II), nickel(II) and copper(II), with the remaining axial coordination sites occupied by chloro ligands to yield high-spin octahedral molecules. A trinuclear structure, based on tetrahedrally coordinated metal ions, is proposed for the zinc(II) complex.     

Three new binuclear copper(II) complexes with isonicotinic acid N-oxide: syntheses,crystal structures and properties

Three new copper(II) complexes with isonicotinic acid N-oxide (HL) and 1,10-phenanthroline (phen) as ligands, [Cu(L)(phen)(H₂O)]₂(NO₃)₂···2H₂O (1), [Cu(L)(phen)(H₂O)]₂(ClO₄)₂···2H₂O (2), and [Cu(L)(phen)Br]₂- [Cu(L)(phen)(H₂O)]₂Br₂···6H₂O (3) have been synthesized and structurally characterized. The structures of all three complexes feature a Cu₂ dimer formed by two Cu(II) ions interconnected by two bridging ligands. Each copper(II) ion has a distorted square pyramidal coordination geometry with elongated axial coordination by an aqua ligand or halogen anion. The isonicotinic acid N-oxide anion is bidentate, being coordinated to two Cu(II) ions through its N-O oxygen and one of its carboxylate oxygen atoms. Magnetic susceptibility measurements show a Curie–Weiss paramagnetic behavior characteristic of one unpaired electron for a copper(II) ion for all three complexes.     

Phase transformation in a nanostructured M300 maraging steel obtained by SPS of mechanically alloyed powders

New complexes of type [Cu(HTBG)₂]Cl₂ (1), [Cu(TBG)₂]·3H₂O (2) and [CuL]·nH₂O (3) L:L¹, n = 2 and (4) L:L², n = 1 (HTBG: 2-tolylbiguanide, L¹ and L²: ligands resulted from 2-tolylbiguanide, ammonia/hydrazine and formaldehyde one pot condensation) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. Redox behaviour was established by cyclic voltammetry. The in vitro qualitative and quantitative antimicrobial activity assays showed that the complexes exhibited variable antimicrobial activity against Gram-negative and Gram-positive strains isolated from the hospital environment. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. After water elimination, complexes have a similar thermal behaviour. Processes as water elimination, melting, chloride anion removal as well as oxidative degradation of the organic ligands were observed. The final product of decomposition was copper (II) oxide.     

Bi-, TRI- and Penta-Nuclear Complexes of Chelating Schiff Bases Derived from o-Acetoacetylphenol and Amine Complexes, [Ni(1,2-pn)2Cl2]·3H2O and [Cu(1,2-pn)2]SO4·2H2O

Two novel macroacylic Schiff base ligands were prepared by condensation of two diamine metal complexes, [Ni(1,2-pn)₂Cl₂]·3H₂O and [Cu(1,2-pn)₂]SO₄·2H₂O with o-acetoacetylphenol. The ligands MH₆L(M = Ni or Cu) are hexabasic and contain two O₄ coordination sites. They act as ligands towards transition metal ions yielding homo- and heteronuclear complexes of the type [NiH₄ LCu(H₂O)₂]·4H₂O, [MH₂LM' ₂(H₂O)₆], [MLM' ₄(H₂O)₈], [MH₂ LCe₂(NO>₃)₂(H₂O)₂] and [NiLTh₂(NO₃)₂(H₂O)₂] (M = Ni or Cu; M' = Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ce(III), Th(IV) and UO₂ (VI)). The complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), IR, visible and ESR spectra, magnetic susceptibility measurements and mass spectrometry. Magnetic moments were altered by the introduction of metal cations besides the one already present in the complex ligands. The M' cations were linked to two ketonic oxygen atoms and two phenyl oxygen atoms in [NiH₆ L(H₂O)₂] and [CuH₆ L] complex ligands. All homo- and hetero-, bi- and tri-nuclear complexes show antiferromagnetic interactions which are attributed to inter- or intramolecular interactions of the metal cations. Mass spectra of the complex ligands and selected homo- and heteronuclear complexes support the formula weights of these complexes. Visible and ESR spectra as well as magnetic moments indicated that the parent mononuclear complex ligands [MH₆ L] have an octahedral geometry for Ni(II) and a square-planar geometry distorted towards tetrahedral for Cu(II). The metal cations in bi-, tri- and pentanuclear complexes are octahedral or square-planar. The octahedral configuration is completed by chloride anions and/or solvent molecules.     

Ternary and binary copper(II) complexes: synthesis,characterization, ROS-inductive,proteasome inhibitory,and anticancer properties

Three ternary copper(II) complexes, [Cu(phen)(L-phe)Cl]·2H₂O, [Cu(phen)(L-leu)Cl]·4½H₂O, and [Cu(phen)(L-tyr)Cl]·3H₂O, and four binary copper(II) complexes, [Cu(phen)Cl₂]_, Cu(L-phe)₂·½H₂O, Cu(L-leu)₂·½H₂O, and Cu(L-tyr)₂·H₂O (where phen = 110-phenanthroline, L-phe = L-phenylalanine, L-tyr = L-tyrosine, L-leu = L-leucine and Cl^- = chloride), were synthesized and characterized by elemental analysis, spectroscopic techniques (FTIR, UV–visible, fluorescence spectroscopy), magnetic susceptibility, molar conductivity, and lipophilicity measurement. X-ray diffraction determination of a single crystal of [Cu(phen)(L-tyr)Cl] showed two independent molecules in the asymmetric unit, each with the same distorted square pyramidal geometry about copper(II). p-Nitrosodimethylaniline assay revealed that the three ternary complexes were better inducers of reactive oxygen species over time than binary complexes, CuCl₂, and free ligands. All the copper(II) complexes in this series inhibited the three proteolytic activities in the order Trypsin-like > Caspase-like > Chymotrypsin-like. In terms of anticancer properties, the copper(II)-phen complexes had GI50 values of less than 4 μM against MCF-7, HepG2, CNE1 and A549 cancer cell lines, more potent than cisplatin.     

Syntheses,crystal structures and characterization of divalent transition metal sulfonate complexes with O-phenanthroline

Two new complexes, [Zn(phen)₂(H₂O)₂]2L·H₂O (1) and [Cu(phen)(L)(H₂O)₂]L·3H₂O (2), where HL?= 4-aminobenzenesulfonic acid and phen = o-phenanthroline, have been synthesized and their crystal structures determined by X-ray diffraction. In the complexes the Cu(II) and Zn(II) atoms revealed two different coordination environments. Complex 1 consists of a cation [Zn(phen)₂(H₂O)₂]²⁺, in which Zn(II) is six-coordinated by four nitrogen atoms from two o-phenanthroline molecules and by two water molecules. Complex 2 has two crystallographically unique Cu(II) ions, where Cu(II) ion is five-coordinate with two nitrogen atoms of o-phenanthroline, two water molecules and one sulfonate oxygen atom. The electrochemical behavior and FT-IR of the two compounds have also been studied in detail.     

Synthesis and characterization of CuII and CoII complexes derived from 2,4,6-tri-(2-pyridyl)-1,3,5-triazine (TPT) by chemical and tribochemical reactions

Four Cu^II and Co^II complexes–[Cu(L₁)Cl₂(H₂O)]3/2H₂O · 1/2EtOH, [Cu(L₁)₂Cl₂]6H₂O, [Co(L₁)Cl₂]3H₂O · EtOH, and [Co₂(L₁)(H₂O)Cl₄]1.5H₂O · EtOH (L₁ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine; TPT)–were synthesized by conventional chemical method and used to synthesize another four metal complexes–[Cu(L₁)I₂(H₂O)]6H₂O, [Cu(L₁)₂I₂]6H₂O, [Co(L₁)I(H₂O)₂]I · 2H₂O, and [Co₂(L₁)I₄(H₂O)₃]–using tribochemical reaction, by grinding it with KI. Substitution of chloride by iodide occurred, but no reduction for Cu^II or oxidation of Co^II. Oxidation of Co^II to Co^III complexes was only observed on the dissolution of Co^II complexes in d₆-DMSO in air while warming. The isolated solid complexes (Cu^II and Co^II) have been characterized by elemental analyses, conductivities, spectral (IR, UV-Vis, ¹H-NMR), thermal measurements (TGA), and magnetic measurements. The values of molar conductivities suggest non-electrolytes in DMF. The metal complexes are paramagnetic. IR spectra indicate that TPT is tridentate coordinating via the two pyridyl nitrogens and one triazine nitrogen forming two five-membered rings around the metal in M : L complexes and bidentate via one triazine nitrogen and one pyridyl nitrogen in ML₂ complexes. In binuclear complexes, L is tridentate toward one Co^II and bidentate toward the second Co^II in [Co₂(L₁)Cl₄]2.5H₂O · EtOH and [Co₂(L₁)I₄(H₂O)₃]. Electronic spectra and magnetic measurements suggest a distorted-octahedral around Cu^II and high-spin octahedral and square-pyramidal geometry around Co^II.     

Synthesis,structural characterization,antimicrobial, DNA-binding,and photo-induced DNA cleavage activity of some bio-sensitive Schiff base copper(II) complexes

Schiff base mixed-ligand copper complexes [CuL¹(phen)Cl₂], [CuL¹(bipy)Cl₂], [Cu(L¹)₂Cl₂], [Cu(L²)₂Cl₂], [CuL²(bipy)Cl₂], and [CuL²(phen)Cl₂] (where L^1?=?4-[3,4-dimethoxy-benzylidene]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazole-3-one; L^2?=?4-[3-hydroxy-4-nitro-benzylidene]-1,5-dimethyl-2-phenyl-1,2-dihydro-pyrazole-3-one; phen?=?1,10-phenanthroline; and bipy?=?2,2′-bipyridine) have been synthesized and characterized. Their DNA-binding properties have been studied by electronic absorption spectra, viscosity, and electrochemical measurements. The absorption spectral and viscosity results suggest that the copper(II) complexes bind to DNA via partial intercalation. The addition of DNA resulting in the decrease of the peak current of the copper(II) complexes indicates their interaction. Interaction between the complexes and DNA has also been investigated by submarine gel electrophoresis. The copper complexes cleave supercoiled pUC19 DNA to nicked and linear forms through hydroxyl radical and singlet oxygen in the presence of 3-mercaptopropionic acid as the reducing agent. These copper complexes promote the photocleavage of pUC19 DNA under irradiation at 360?nm. Mechanistic study reveals that singlet oxygen is likely to be the reactive species responsible for the cleavage of plasmid DNA by the synthesized complexes. The in vitro antimicrobial study indicates that the metal chelates have higher activity against the bacterial and fungal strains than the free ligands.     

Synthesis, Spectral and Thermal Analyses of Novel Bi- and Polyhomonuclear Complexes of Pyrimidine Bisazo-dianil Derivatives

Seven new bi‐ and polyhomonuclear transition metal complexes with three polyhydroxlated bisazodianil ligands were synthesized and characterized. The ligands were derived from condensation of 6‐(5‐formyl‐2‐hydroxyphenylazo)‐2,4‐dihydroxypyrimidine with aliphatic diamines (H₈L¹, H₈L² and H₆L³). The data of elemental and thermal analyses, molar conductance measurement, IR, electronic and ESR spectra as well as magnetic moment measurements support the formation of [L¹Co₇Cl₆(H₂O)₁₀]·22H₂O ( 1 ), [H₂L²Mn₆Cl₆(H₂O)₈]·3H₂O·2EtOH ( 3 ), [L²Co₈Cl₈(H₂O)₁₂]·24H₂O ( 4 ), [H₄L³Co₂Cl₂(H₂O)₂]·8H₂O·2EtOH ( 6 ) with a tetrahedral geometry and [H₂L¹Ni₅Cl₄(H₂O)₁₆]·19H₂O·EtOH ( 2 ), [L²Ni₈Cl₈(H₂O)₂₈]·8H₂O·EtOH ( 5 ) with an octahedral geometry while [H₆L³Cu₃(H₂O)₇]Cl₃·10H₂O ( 7 ) has a distorted tetrahedral arrangement. The mode of bonding between the metal ions and the ligand molecules is determined and the metal‐metal interaction was studied. The activation thermo‐kinetic parameters for the thermal decomposition steps of the complexes E*, ΔH*, ΔS*, and ΔG* were calculated.     

Copper(II) and Cadmium(II) Complexes Based on N,N‐Bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine Ligand: Syntheses,Structures, Magnetic,and Luminescent Properties

The reaction of the aryl‐oxide ligand H₂L [H₂L = N,N‐bis(3, 5‐dimethyl‐2‐hydroxybenzyl)‐N‐(2‐pyridylmethyl)amine] with CuSO₄ · 5H₂O, CuCl₂ · 2H₂O, CuBr₂, CdCl₂ · 2.5H₂O, and Cd(OAc)₂ · 2H₂O, respectively, under hydrothermal conditions gave the complexes [Cu(H₂L¹)₂] · SO₄ · 3CH₃OH ( 1 ), [Cu₂(H₂L²)₂Cl₄] ( 2 ), [Cu₂(H₂L²)₂Br₄] ( 3 ), [Cd₂(HL)₂Cl₂] ( 4 ), and [Cd₂(L)₂(CH₃COOH)₂] · H₂L ( 5 ), where H₂L¹ [H₂L¹ = 2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenol] and H₂L² [H₂L² = 2‐(2, 4‐dimethyl‐6‐((pyridin‐2‐ylmethylamino)methyl)phenoxy)‐4, 6‐dimethylphenol] were derived from the solvothermal in situ metal/ligand reactions. These complexes were characterized by IR spectroscopy, elementary analysis, and X‐ray diffraction. A low‐temperature magnetic susceptibility measurement for the solid sample of 2 revealed antiferromagnetic interactions between two central copper(II) atoms. The emission property studies for complexes 4 and 5 indicated strong luminescence emission.     

Cobalt(II), nickel(II), and copper(II) complexes of 14-membered hexaazamacrocycles: synthesis and characterization

Cobalt(II), nickel(II), and copper(II) complexes containing 5,12-di(4-bromophenyl)-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H₂L¹) and 5,12-diphenyl-7,14-dimethyl-1,2,4,8,9,11-hexaazacyclotetradeca-7,14-diene-3,10-dione (H₂L²) have been synthesized. All complexes were characterized by elemental analysis, MALDI TOF-MS spectrometry, and electronic absorption spectroscopy. The crystal structures of two compounds, [Cu₂(H₂L¹)Cl₄]_n and [NiL²], were determined by X-ray powder diffraction. In the polymeric [Cu₂(H₂L¹)Cl₄]_n, the Cu₂Cl₄ units and H₂L¹ molecules are situated on inversion centers. Each Cu(II) has a distorted trigonal-bipyramidal coordination environment formed by N and O from H₂L¹ [Cu–N 2.340(14)?Å, Cu–O 1.952(11)?Å], two bridging chlorides [Cu–Cl 2.332(5), 2.279(5)?Å] and one terminal chloride [Cu–Cl 2.320(6)?Å]. In the [NiL²] complex, the Ni(II) situated on inversion center has a distorted square-planar coordination environment formed by four nitrogens from L² [Ni–N 1.860(11), 1.900(11)?Å].     

Metal Derivatives of Thiosemicarbazones: Crystal and Mole­cular Structures of Mono‐ and Dinuclear Copper(II) Complexes with N1‐Subsitituted Salicylaldehyde Thiosemicarbazones

Reactions of copper(II) acetate with N¹‐subsitituted salicylaldehyde thiosemicarbazones [R¹R²C²=N³–N²H–C¹(=S)–N¹HR³;R¹ = 2‐HO–C₆H₄–, R² = H : R³ = Me (H₂L¹), Et (H₂L²)] are described. Copper(II) acetate was reacted with H₂L¹ and H₂L² ligands in the presence of polypyridyl co‐ligands, and this led to the formation ofmononuclear complexes, [Cu(κ³‐O, N, S‐L¹)(κ²‐N, N‐bipy)] ( 1 ),[Cu(κ³‐O, N, S‐L)(κ²‐N, N‐phen)] [L = L¹ ( 3 ), L² ( 4 )], [Cu(κ³‐O, N, S‐L)(κ²‐N, N‐tmphen)] [L =L¹ ( 5 ), L² ( 6 )] and a dinuclear complex, [Cu₂L²₂(bipy)] ( 2 ) (bipy = 2, 2′‐bipyridine, phen = 1, 10‐phenanthroline, tmphen = 3, 4, 7, 8‐tetramethyl‐1, 10‐phenanthroline). In dinuclear complex 2 , one ligand is O, N³,S‐chelating, while second is O, N³,S‐chelation‐cum‐N²‐bridging; and in all others thio‐ligands are O, N³,S‐chelating. The μ_eff values for the complexes lie in the range of 1.79–1.83 BM. Complexes 1 , 3 – 6 have square pyramidal arrangement, whereas complex 2 has two independent molecules in the crystal lattice, and each molecule has trigonal bipyramidal square planar (5:4) coordination pair. Complexes 2 , 4 , and 6 showed fluorescence properties.     

Antitumor Activity and Physicochemical Properties of New Thiosemicarbazide Derivative and Its Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) Complexes

A novel biologically active thiosemicarbazide derivative ligand L (N-[(phenylcarbamothioyl)amino]pyridine-3-carboxamide) and a series of its five metal(II) complexes, namely: [Co(L)Cl₂], [Ni(L)Cl₂(H₂O)], [Cu(L)Cl₂(H₂O)], [Zn(L)Cl₂] and [Cd(L)Cl₂(H₂O)] have been synthesized and thoroughly investigated. The physicochemical characterization of the newly obtained compounds has been performed using appropriate analytical techniques, such as ¹H and ^l3C nuclear magnetic resonance (NMR), inductively coupled plasma (ICP), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and magnetic measurements. In order to study the pharmacokinetic profile of the compounds, ADMET analysis was performed. The in vitro studies revealed that the synthesized compounds exhibit potent biological activity against A549 human cancer cell line.     

RUTHENIUM (II) COMPLEXES IN CATALYTIC OXIDATION

Abstract

Ruthenium (II) complexes of the type RuL(CO)₂Cl₂, [RuL(CO)₂L^? ₂]²⁺ and [RuL(CO)₂Cl L′]⁺ [L = bipyridine (bpy), phenanthroline (phen), biquinoline (biq) and L′ = pyridine (py), 4-chloropyridine (Cl-py), 4-methoxypyridine (MeO-py)] were synthesized from [Ru(CO)₂Cl₂]_n and L, to produce the intermediate RuL(CO)₂Cl₂ followed by hydrolysis and reaction with L′. The catalytic activity of these complexes in epoxidation of olefins with iodosylbenzene under ambient conditions was investigated. A possible mechanism of these reactions, explaining the effects of the ligands on the reaction was explored. At least one carbonyl ligand remained bound to the metal through the reaction. The formation of an oxo intermediate was inferred from spectroscopic detection of bridged oxygen Ru—O—Ru and Ru=O species.     

Regularities of the formation of binuclear homo- and heteroleptic complexes of <Emphasis Type="Italic">d</Emphasis> metals with 3,3′-bis(dipyrrolylmethenes) in DMF

The reactions of seven symmetrically alkylated tetradentate ligands 3,3′-bis(dipyrrolylmethenes) (H₂L) with d-metal acetates (M(AcO)₂) in DMF solutions at 298.15 K were studied by spectrophotometry. Helicands H2L were found to be structurally preorganized to form stable binuclear homoleptic two-helix helicates [M₂L₂] with Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Hg(II) acetates. The coordination of the ligands by the metal ions included consecutive stages of formation of the heteroleptic [M₂L(AcO)₂] and homoleptic [M₂L₂] complexes. The [M₂L(AcO)₂] complexes were spectrally revealed in solutions containing a ligand excess (c _{H 2 L} / c _{M(AcO) 2} > 1). An increase in the salt concentration shifted the system of equilibria to the homoligand product [M₂L₂]. The thermodynamic constants of the reactions increased in the series of complexing agents: Cu(II) < Cd(II) < Hg(II) < Ni(II) < Co(II) < Zn(II). An analysis of the data on the thermodynamic constants of [M₂L₂] helicate formation in solutions and the earlier obtained results of the IR and ¹H NMR studies of the hydrobromic salts of the ligands (H₂L · 2HBr) showed that the key regularities of the influence of the structural factors on the coordination properties of the ligands were in an increase in the stability of the [M₂L₂] complexes with an increase in the basicity of the ligands.     

Synthesis,Structural Characterization,and Antimicrobial Activities of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) Complexes of Triazole‐based Azodyes

The synthesis and characterization of new transition metal complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3‐(2‐hydroxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL¹ ) and 3‐(2‐hydroxy‐3‐carboxynaph‐1‐ylazo)‐1,2,4‐triazole ( HL² ) have been carried out. Their structures were confirmed by elemental analyses, thermal analyses, spectral and magnetic data. The IR and ¹H NMR spectra indicated that HL¹ and HL² coordinated to the metal ions as bidentate monobasic ligands via the hydroxyl O and azo N atoms. The UV‐Vis, ESR spectra and magnetic moment data revealed the formation of octahedral complexes [Mn L¹ (AcO)(H₂O)₃] ( 1 ), [Co L¹ (AcO)(H₂O)₃]·H₂O ( 2 ), [Mn L² (AcO)(H₂O)₃] ( 6 ) and [Co L² (AcO)(H₂O)₃] ( 7 ), [Ni L¹ (AcO)(H₂O)] ( 3 ), [Zn L¹ (AcO)(H₂O)]·H₂O ( 5 ), [Ni L² (AcO)(H₂O)] ( 8 ), [Zn L² (AcO)(H₂O)]·10H₂O ( 10 ) have tetrahedral geometry, whereas [Cu L¹ (AcO)(H₂O)₂] ( 4 ) and [Cu L² (AcO)(H₂O)₂]·5H₂O ( 9 ) have square pyramidal geometry.. The mass spectra of the complexes under EI‐con‐ ditions showed the highest peaks corresponding to their molecular weights, based on the atomic weights of ⁵⁵Mn, ⁵⁹Co, ⁵⁸Ni, ⁶³Cu and ⁶⁴Zn isotopes; besides, other peaks containing other isotopes distribution of the metal. Kinetic and thermodynamic parameters of the thermal decomposition stages were computed from the thermal data using Coats‐Redfern method. HL² and complexes 6 – 10 were found to have moderate antimicrobial activities against Staphylococcus aureus (gram positive), Escherichia coli (gram negative) and Salmonella sp bacteria, and antifungal activity against Fusarium oxysporum, Aspergillus niger and Candida albicans. Also, in most cases, metallation increased the activity compared with the free ligand.     

Metal Complexes Derived from Hydrazoneoxime Ligands: I. Synthesis,Characterization and Magnetochemical Studies of (Acylhydrazoneoxime) Copper(II) Complexes

Reactions of 2-hydroxyimino-1-methylpropylidene (acetyl-) and (benzoylhydrazine) with copper(II) chloride, nitrate and acetate were studied. Three types of copper(II) complexes of general formula [Cu(H₂L)Cl₂], [{Cu(HL)}₂][sdot]2NO₃[sdot]nH₂O and [{Cu(L)}₂], where H₂L, HL, and L refer, respectively, to the neutral, monoanionic and dianionic ONN tridentate acylhydrazoneoxime ligands, were isolated and characterized. Variable-temperature magnetic susceptibility measurements for [Cu(H₂L)Cl₂] suggest Curie-Weiss behavior. Both [{Cu(HL)}₂][sdot]2NO₃[sdot]nH₂O and [{Cu(L)}₂] show strong antiferromagnetic exchange coupling with ? 2J values of 898-934 and 718-757 cm^?1, respectively, indication dimeric structures with oximate bridges.     

Synthesis,characterization, and biological activity studies on (E)-N′-[2-hydroxy-1,2-di(pyridin-2-yl)ethylidine]aroyl hydrazides and their copper(II) complexes

The reaction of copper(II) salts with (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene)aroyl hydrazide (H₂L¹, H₂L², H₃L³) or (E)-N-(2-hydroxy-1,2-di(pyridin-2-yl)ethylidene) isonicotinohydrazide (H₂L⁴) afforded the complexes [(L)Cu(H₂O)₃], [(H₂L)Cu(OAc)(H₂O)], [(HL)Cu(OAc)] _n , [(H₂L)Cu(H₂O)](ClO₄)₂ and [(H₂L)Cu(OAc)(H₂O)], where n = 1 or 2 and L is the dinegative ion of the ligands. The ligands and their complexes are characterized by elemental analyses, spectral (IR, NMR, electronic, and ESR) and magnetic studies. The FT-IR indicates that the ligands are neutral or anionic polydentate. The number of the coordinating centers depends on the nature of the metal used and the reaction conditions. The room temperature magnetic moment values, electronic spectra and ESR data indicate square planar, trigonal bipyramidal, square pyramidal, and distorted octahedral ligand fields around copper(II). Thermal decomposition of the complexes was monitored by TG and DTG under N₂ and the thermal decomposition mechanisms are given. The compounds were screened for their antimicrobial activities on some Gram-positive and Gram-negative bacterial species. The free ligands are inactive against all studied bacteria. The complexes have variable activity with the most active [(H₂L)Cu(H₂O)](ClO₄)₂, where H₂L is H₂L¹ or H₂L². The minimum inhibition concentrations for these two complexes were determined. These biological activity results are related to the structures of the compounds.     

Preparation,characterization and biological activity of novel metal-NNNN donor Schiff base complexes

Novel Schiff base (H₂L) ligand is prepared via condensation of benzil and triethylenetetraamine. The ligand is characterized based on elemental analysis, mass, IR and ¹H NMR spectra. Metal complexes are reported and characterized based on elemental analyses, IR, ¹H NMR, solid reflectance, magnetic moment, molar conductance, and thermal analyses (TG, DTG and DTA). 1:1 [M]:[H₂L] complexes are found from the elemental analyses data having the formulae [M(H₂L)Cl₂]·yH₂O (M = Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)), [Fe(H₂L)Cl₂]Cl·H₂O, [Th(H₂L)Cl₂]Cl₂·3H₂O and [UO₂(H₂L)](CH₃COO)₂·2H₂O. The metal chelates are found to be non-electrolytes except Fe(III), Th(IV) and UO₂(II) complexes are electrolytes. IR spectra show that H₂L is coordinated to the metal ions in a neutral tetradentate manner with 4Ns donor sites of the two azomethine N and two NH groups. The geometrical structures of these complexes are found to be octahedral. The thermal behaviour of these chelates is studied where the hydrated complexes lose water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters are calculated using Coats–Redfern method. The ligand (H₂L), in comparison to its metal complexes, is screened for its antibacterial activity. The activity data show that the metal complexes have antibacterial activity more than the parent Schiff base ligand and cefepime standard against one or more bacterial species.