Formation of polymeric chain assemblies of transition metal complexes with a multidentate Schiff-base

The new multidentate Schiff-base (E)-6,6′-((1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1-ylidene))bis(methan-1-yl-ylidene))bis(4-methyl-2-((E)(pyridine-2-ylmethylimino)methyl)phenol) H₂L and its polymeric binuclear metal complexes with Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) are reported. The reaction of 2,6-diformyl-4-methyl-phenol with ethylenediamine in mole ratios of 2:1 gave the precursor 3,3′-(1E,1′E)-(ethane-1,2-diylbis(azan-1-yl-1ylidene))bis(methan-1-yl-1-ylidene)bis(2-hydroxy-5-methylbenzaldehyde) W. Condensation of the precursor with 2-(amino-methyl)pyridine in mole ratios of 1:2 gave the new N₆O₂ multidentate Schiff-base ligand H₂L. Upon complex formation, the ligand behaves as a dibasic octadentate species with the involvement of the nitrogen atoms of the pyridine groups in coordination for all complexes. The mode of bonding and overall geometry of the complexes were determined through physico-chemical and spectroscopic methods. These studies revealed octahedral geometries for Cr(III), Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Cd(II) and Hg(II) complexes of general formulae [Cr₂^III(L)Cl₂]Cl₂, [Ni₂^II(L)(H₂O)₂]Cl₂ and [M₂(L)Cl₂] and five co-ordinate Zn(II) complex of general formula [Zn₂^II(L)]Cl₂.     

Antibacterial activity of ruthenium(II) carbonyl complexes containing tetradentate Schiff bases

Several new hexa-coordinated ruthenium(II) complexes of the type [Ru(CO)(LL)(B)] (where, LL = anthacac, anthdibm, 2-amtpacac or 2-amtpdibm; B = PPh₃ or py or pip or morph) have been prepared by reacting [RuHCl(CO)(PPh₃)₃] or [RuHCl(CO)(PPh₃)₂(B)] with tetradentate Schiff bases such as bis(anthranilic acid)acetylacetimine (H₂-anthacac), bis(anthranilic acid) dibenzoylmethimine (H₂-anthdibm), bis(2-aminothiophenol) acetylacetimine (H₂-2-amptacac) or bis(2-aminothiophenol) dibenzoylmethimine (H₂-2-amtpdibm). The complexes have been characterised by elemental analyses and spectral (i.r., electronic spectra, ¹H- and ³¹P-n.m.r.) data. An octahedral structure has been tentatively proposed for the complexes, which were also tested for their antibacterial properties.     

Synthesis,structure determination,and magnetic properties of pentakis[ bis (hexafluoroacetylacetonato)1,2,4-triazinecopper(II)]

Reaction of bis(hexafluoroacetylacetonato)copper(II) hydrate with 1,2,4-triazine (tz) in dichloromethane yields pentakis[bis(hexafluoroacetylacetonato)triazinecopper(II)] [Cu(hfac)₂(tz)]₅ (hfac = hexafluoroacetylacetonate) (1). The complex crystallizes in the triclinic space group P-1, with cell parameters a = 11.4124(5), b = 13.3405(5), c = 16.1794(7) Å, α = 93.360(2)°, β = 108.700(2)°, γ = 100.293(2)° at 120(1) K. In the complex, the copper(II) ions show three types of coordination polyhedra: square planar, square pyramidal, and octahedral (4 + 2). The tz ligand also shows different coordination modes (bridging and monodentate). In addition, disorder is observed in the triazine molecule, either through non-crystallographic two-fold rotation about the longitudinal N,N-axis, or with respect to a crystallographic center of symmetry. The crystal structure of 1 consists of alternating trimers and dimers. The weak coordination of the tz molecules results in negligible magnetic exchange through the ring.     

Oxomolybdenum(V) complexes of bis-(2-benzimidazolyl) alkanes

Summary Oxomolybdenum(V) complexes of the type (LH₄) [MoOCl₅] (where LH₂ = dimethylene bis-2-benzimidazole or tetramethylene bis-2-benzimidazole), [MoOCl₃(LH₂)] (where LH₂ = tetramethylene bis-2-benzimidazole), [(Mo₂O₄Cl₂-(H₂O)₃)₂(LH₂)] (where LH₂ = dimethylene bis-2-benzimidazole, tetramethylene bis-2-benzimidazole or hexamethylene bis-2-benzimidazole) and [Mo₂O₃Cl₄(LH₂)₂] (where LH₂ = tetramethylene bis-5-nitro-2-benzimidazole) were prepared and characterised. The mononuclear complexes show u.v.-vis. absorptions characteristic of octahedral molybdenum(V). The dinuclear complexes do not absorb in the visible region, possibly due to the presence of an Mo₂O ₄ ^{2 +}} core, which is also indicated by their diamagnetic behaviour. The biological activities of the free ligands and their complexes have been studied.     

Crystal Structure and Magnetism of (μ-Maleato)Bis[(N-(2-(Diethylamino)Ethyl)-Salicylidenaminato)Copper(II)]- Methanol

The crystal and molecular structure of ( w -maleato)bis[(N-(2-(diethylamino)ethyl)salicylidenaminato)-copper(II)]-methanol, [Cu₂(salNet₂)₂( w -mal)]·CH₃OH, where salNet₂ = N-(2-(diethylamino)ethyl)salicylidenaminate, has been determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic space group P2₁/c, with a =11.994(1), b =14.723(1), c =20.0384(1) Å, and g =96.145(2)°. In the structure two copper(II) ions are bridged by the maleato ligand, which coordinates as a monodentate through its first carboxylato group and as a bis-monodentate ligand through its second carboxylato group. The local geometry around the first copper(II) ion is square planar, whereas that around the second is square pyramidal. Fitting of variable-temperature magnetic susceptibility data to the HDVV ? = -2J?₁?₂, S ₁ = S ₂ = 1/2 spin exchange model, yields of 2J value of -4.56 cm^-1. The mechanism of the observed antiferromagnetic interactions is discussed in the light of extended Hückel calculations. Analysis shows an almost linear dependence of the magnitude of the exchange coupling constant, |2J|, upon the calculated energy difference between the two SOMOs for a series of w -dicarboxylato-bridged bis-Cu(salNet₂) complexes.     

Catalase-like catalytic reaction of the dinuclear manganese–salen complex

Catalase-like activity of a dinuclear manganese-salen (Mn–salen) complex, [Mn(salen)(H₂O)]₂(ClO₄)₂ (salen = N,N ′-bis(salicylidene)-1,2-diaminoethane), was investigated. The dinuclear Mn–salen complex exhibits higher catalase-like activity than that of the mononuclear Mn–salen compound, and its activity can be enhanced by an external base. Different reaction intermediates in the presence and absence of an external base were observed, and the catalytically active species was dimeric as evidenced by UV-Vis spectroscopic studies and mass spectrometry data.     

Synthesis,spectral characterization,and antidiabetic study of new furan-based vanadium(IV) complexes

We have synthesized furan-based vanadium complexes, bis(5-nitrofuran-2-carboxylato)oxovanadium(IV) – [VO(5NF)₂], bis(1-furan-2-yl-ethanonato)oxovanadium(IV) sulfate – [VO(2AF)₂]SO₄, and bis(5-methyl-2-furalato)oxovanadium(IV) sulfate – [VO(MFFA)₂]SO₄ possessing [VO(O₄)] coordination mode. These complexes are characterized by physico-chemical and spectroscopic methods. Based on electron paramagnetic resonance parameters, the proposed geometry is close to a distorted square pyramid. Animal study was carried out using standard protocol and the complete profile of glucose, protein, and total cholesterol levels were analyzed followed by an oral glucose tolerance test.     

Novel structurally characterized hetero-bimetallic [Zn(II)2M(II)] (M = Ca and Sr) bis(salamo)-type complexes: DFT calculation,Hirshfeld analyses,antimicrobial and fluorescent properties

Two hetero-bimetallic [Zn(II)₂M(II)] (M = Ca and Sr) complexes [Zn₂Ca(L)(OAc)₂] ( 1 ) and [Zn₂Sr(L)(OAc)₂] ( 2 ) with a novel asymmetrical bis(salamo)-type tetraoxime ligand (H₅L) were designed and synthesized, and characterized by elemental analyses, FT-IR spectra, UV–vis absorption spectra, Density Functional Theory (DFT) calculation, Hirshfeld surface analyses and X-ray single crystal diffractions. Compared with the symmetric bis(salamo)-type ligands, the ligand H₅L and its [Zn(II)₂M(II)] (M = Ca and Sr) asymmetrical bis(salamo)-type complexes synthesized for the first time in this paper have more novel structures and better properties. The results of ultraviolet titration show that the coordination ratio of ligand, alkaline earth metal and transition metal is 1:1:2. Complexes 1 and 2 have good luminescent properties and obvious antimicrobial activities.     

Synthesis,characterization and oxygen affinity of Mn(II), Co(II) and Ni(II) complexes of diethylenetriamine Schiff bases

N,N′-diethyleneamine bis(salicylideneimine); H₂DETS and N,N′-diethyleneamine bis(o-hydroxyacetophenoneimine); H₂DETHA have been prepared to produce Mn(II), Co(II) and Ni(II) complexes by the addition of the synthesized Schiff bases to the studied ions under nitrogen. H₂DETS and H₂DETHA are neutral tridentate in the nitrato complexes and binegative pentadentate in the other complexes. A square pyramidal structure was suggested for all complexes based on elemental analysis, molar conductivity, infrared, electronic spectra and magnetic moment measurements. The oxygen absorption properties were studied for the isolated complexes by considering the solubility, oxygen affinity and stability. [Co(DETS)]·4H₂O has the highest affinity. Different concentrations for the Co(II) complex were studied.     

Complexes of substituted dipyridylpyridazines with palladium(II) and platinum(II)

Reactions of 3,6-bis(2′-pyridyl)pyridazine derivatives (n-dppn)¶ ¶For the n-dppn ligands, n stands for the size of the cyclic aliphatic ring on positions 4 and 5 of the pyridazine ring, n?=?5, 6, 8, and 12. with MX₂(PhCN)₂ (M?=?Pd, Pt; X?=?Cl,?Br) have been investigated. The new complexes cis-[PdCl₂(n-dppn)] (n?=?5,?6,?8,?12), cis-[PtCl₂(n-dppn)]?·?H₂O (n?=?5,?6), cis-[PtCl₂(8-dppn)] and cis-[PtBr₂(5-dppn)] have been characterized by elemental analyses, conductivity measurements, infrared, electronic and ¹H-NMR spectra.     

Synthesis,characterization and comparative studies of mono- and dimeric copper(II) complexes containing tripodal ligands

Mono and dimeric bromo-bridged copper(II) complexes of the type [CuBr₂(L)] and [Cu₂Br₂(L)₂](ClO₄)₂ containing nitrogen donor tripodal ligands L = 2,6-bis(pyrazol-1-yl)pyridine (bppy) or 2,6-bis(3,5-dimethylpyrazol-1-yl)pyridine (dmbppy) have been synthesized. All complexes have been characterized by elemental analysis, IR, ESR and electronic spectra and magnetic susceptibility and cyclic voltammetry measurements.     

Preparation and characterization of binuclear CuII complexes derived from diamines and dialdehydes

New macrocyclic complexes were synthesized by template reaction of 1,7-bis(2-formylphenyl)-1,4,7-trioxaheptane, 1,4-bis(2-carboxyaldehydephenoxy)butane or 1,3-bis(2-carboxyaldehydephenoxy)propane with 1,4-bis(2-aminophenoxy)butane, 1,3-bis(2-aminophenoxy)butane, 1,4-bis(4-chloro-2-aminophenoxy)butane or 1,3-bis(4-chloro-2-aminophenoxy)butane and Cu(NO₃)₂ ·?3H₂O or Cu(ClO₄)₂ ·?6H₂O, respectively. The complexes have been characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV–Vis spectra, magnetic susceptibility, conductivity measurements and mass spectra. All complexes are diamagnetic and binuclear.     

Coordination of di- and triimine ligands at ruthenium(II) and ruthenium(III) centers: structural,electrochemical and radical scavenging studies

Herein, we explore the coordination of di- and triimine chelators at ruthenium(II) and ruthenium(III) centers. The reactions of 2,6-bis-((4-tetrahydropyranimino)methyl)pyridine (thppy), N¹,N²-bis((3-chromone)methylene)benzene-1,2-diamine (chb), and tris-((1H-pyrrol-2-ylmethylene)ethane)amine (H₃pym) with trans-[Ru^IICl₂(PPh₃)₃] afforded the diamagnetic ruthenium(II) complex cis-[RuCl₂(thppy)(PPh₃)] (1) and the paramagnetic complexes [mer-Ru₂(μ-chb)Cl₆(PPh₃)₂] (2), and [Ru(pym)] (3), respectively. The complexes were characterized by IR, NMR, and UV–vis spectroscopy and molar conductivity measurements. The structures were confirmed by single crystal X-ray diffraction studies. The redox properties of the metal complexes were probed via cyclic- and squarewave voltammetry. Finally, the radical scavenging capabilities of the metal complexes towards the NO and 2,2-di(4-tert-octylphenyl)-1-picrylhydrazyl (DPPH) radicals were investigated     

Investigations on the stability of bendamustin, a cytostatic agent of the nitrogen mustard type, I. Synthesis, isolation, and characterization of reference substances

Summary The following compounds were chosen as reference substances for HPLC investigations on 4-(6-bis(2-chloro-ethyl)amino-3-methylbenzimidazoyl(2))butyric acid (bendamustin), an antineoplastic agent of the N-lost type (synthesized or isolated from crude bendamustin): 4-(6-((2-chloroethyl)(2-hydroxyethyl)amino)-3-methylbenzimidazoyl(2))butyric acid (HP1), 4-(6-bis(2-hydroxyethyl)amino-3-methylbenzimidazoyl(2))butyric acid (HP2), ethyl-4-(6-bis(2-hydroxyethyl)amino-3-methylbenzimidazoyl(2))butyrate (dihydroxyester), and ethyl-4-(6-bis(2-chloroethyl)amino-3-methylbenzimidazoyl(2))butyrate (dichloroester). Furthermore, the so far unidentified side product 4-(7,8-dihydro-6-(2-chloroethylamino)-3-methyl-1,4-thiazino[3,2-g]benzimidazoyl(2))-butyric acid (NP1), formed in the last step of the synthesis, was isolated and identified.

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Untersuchungen zur Stabilität von Bendamustin, einem Cytostatikum vom N-Lost-Typ, 1. Mitt.: Synthese, Isolierung und Charakterisierung von Vergleichssubstanzen

Zusammenfassung Die folgenden Verbindungen wurden als Vergleichssubstanzen für HPLC-analytische Untersuchungen von 4-(6-Bis(2-chlorethyl)amino-3-methylbenzimidazoyl(2))buttersäure (Bendamustin), einem Antitumormittel des N-lost-Typs, synthetisiert oder aus Bendamustin-Rohstoff vor der Endreinigung isoliert: (4-(6-((2-Chlorethyl)(2-hydroxyethyl)amino)-3-methylbenzimidazoyl(2))buttersäure (HP1), 4-(6-Bis(2-hydroxyethyl)amino-3-methylbenzimidazoyl(2))buttersäure (HP2), 4-(6-Bis(2-hydroxyethyl)amino-3-methylbenzimidazoyl(2))buttersäureethylester (Dichlorester). Weiterhin konnte das bislang unbekannte Nebenprodukt 4-(7,8-Dihydro-6-(2-chlorethylamino)-3-methyl-1,4-thiazino[3,2-g]benzimidazoyl(2))buttersäure (NP1), welches sich im letzten Schritt der Synthese bildet, isoliert und identifiziert werden.

     

Regioselectivity in the Reactions of Bis-hydrazonoyl Halides with Pyrimidine-2-thiones

Summary.  Bis-hydrazonoyl chlorides react regioselectively with pyrimidine-2-thiones, which contain a masked thiourea residue, to give the hitherto unknown annelated 2,3-bis-arylhydrazono-thiazoles and 3,3′-bis-1,2,4-triazoles. Reaction of bis-hydrazonoyl chlorides with 2-methylthio derivatives gave only 3,3′-bis-1,2,4-triazoles. Received October 4, 2000. Accepted (revised) December 20, 2000     

DI-μ-CHLORO-BIS[l,2-BIS(DIPHENYLPHOSPHINO)-ETHANEPALLADIUM(II)]: SYNTHESIS AND CRYSTAL STRUCTURE

Abstract

On reacting 1,2-bis(diphenylphosphino)ethanedichloropalladium(II) with equimolar amount of silver perchlorate, a binuclear complex, di-μ-chloro-bis[1,2-bis(diphenylphosphino)ethane-palladium(II)] (1) is formed. The crystal structure of 1 has been solved. It crystallizes with two chloroform molecules. Chloro bridges are symmetrical and normal (Pd-Cl～2.414(3) Å). The immediate environment around palladium is slightly distorted square planar and the P-Pd-P angle is ～85°. IR bands at 290 and 270cm^?1 are observed for the chloro-bridged core of the complex.     

Synthesis and characterization of manganese(II), nickel(II), copper(II) and zinc(II) Schiff-base complexes derived from 1,10-phenanthroline-2,9-dicarboxaldehyde and 2-mercaptoethylamine

The synthesis of a new Schiff base containing 1,10-phenanthroline-2,9-dicarboxaldehyde and 2-mercaptoethylamine is described. The reaction of 1,10-phenanthroline-2,9-dicarboxaldehyde with 2-mercaptoethylamine leads to 2,9-bis(2-ethanthiazolinyl)-1,10-phenanthroline (I) which undergoes rearrangement when reacted with manganese, nickel, copper or zinc ions to produce complexes of the tautomeric Schiff base 2,9-bis[2-(2-mercaptoethyl)-2-azaethene]-1,10-phenanthroline (L). The [M(L)Cl₂] complexes [where M = Mn(II), Ni(II), Cu(II) and Zn(II) ions] were characterized by physical and spectroscopic measurements which indicated that the ligand is a tetradentate N₄ chelating agent.     

Regioselectivity in the Reactions of Bis -hydrazonoyl Halides with Pyrimidine-2-thiones

 Bis-hydrazonoyl chlorides react regioselectively with pyrimidine-2-thiones, which contain a masked thiourea residue, to give the hitherto unknown annelated 2,3-bis-arylhydrazono-thiazoles and 3,3′-bis-1,2,4-triazoles. Reaction of bis-hydrazonoyl chlorides with 2-methylthio derivatives gave only 3,3′-bis-1,2,4-triazoles.     

Reactions of Bis(β-Alaninato) Metal(II) Complexes with Formaldehyde and Benzamide: The Crystal Structure of Bis[N-Methyl-N-(N′-Methyl-Benzamido)-β-Alaninato]Copper(II) Monohydrate and Characterization of Bis[N,N-DI(N′-Methylbenzamido)-β-Alaninato]Metal(II) Complexes

The bis[N-methyl-N-(N'-methylbenzamido)-β-alaninato]copper(II), Cu(II)[Me-MeBA]₂, is synthesized by reacting bis(β-alaninato)copper(II) with formaldehyde and benzamide in the presence of a base (NaOH) over the pH range 5.5-8.5. However, the bis[N,N-di (N'-methylbenzamido)-β-alaninato]metal(II) complexes, M(II)[DMeBA]₂ (M = Zn, Ni, Co), are obtained when the respective bis(β-alaninato)metal(II) reacts with formaldehyde and benzamide in the presence of the base in similar pH ranges. Nevertheless, Cu(II)[DMeBA]₂ can be synthesized if the reaction is carried out in the absence of base. The M(II)[DMeBA]₂ complexes are characterized by elemental analysis, IR and UV-Visible spectroscopy and magnetic susceptibility measurements. X-ray crystal structure analysis of Cu(II)[Me-MeBA]₂ suggests that the N'-methylbenzamido substituent of the β-alanine moiety is formed through Mannich aminomethylation, and that the other N-methyl substituent is formed via a Canizzaro-type methylation.     

Synthesis and characterization of a cationic oxorhenium(V) complex containing the pentadentate N3O2-donor ligand bis ( N -methylsalicylideneiminopropyl)amine

The complex salt [ReO(bsa)]PF₆ (H₂bsa?=?bis(N-methylsalicylideneiminopropyl)amine) was prepared from the reaction of cis-[ReO₂I(PPh₃)₂] with H₂bsa in toluene. The dianionic pentadentate ligand bsa is coordinated to the ReO³⁺ moiety via one secondary amino and two imino nitrogens, and two anionic phenolate oxygens. The complex was characterized by spectroscopy and analytical data, and the structure has been determined by single-crystal X-ray diffraction analysis.