Syntheses,characterization, and crystal structures of ruthenium(II)/(III) complexes with tridentate salicylaldiminato ligands

Treatment of [Ru(PPh₃)₃Cl₂] with one equivalent of tridentate Schiff base 2-[(2-dimethylamino-ethylimino)-methyl]-phenol (HL) in the presence of triethylamine afforded a ruthenium(III) complex [RuCl₃(κ²-N,N-NH₂CH₂CH₂NMe₂)(PPh₃)] as a result of decomposition of HL. Interaction of HL and one equivalent of [RuHCl(CO)(PPh₃)₃], [Ru(CO)₂Cl₂] or [Ru(tht)₄Cl₂] (tht = tetrahydrothiophene) under different conditions led to isolation of the corresponding ruthenium(II) complexes [RuCl(κ³-N,N,O-L)(CO)(PPh₃)] (2), [RuCl(κ³-N,N,O-L)(CO)₂] (3), and a ruthenium(III) complex [RuCl₂(κ³-N,N,O-L)(tht)] (4), respectively. Molecular structures of 1·CH₂Cl₂, 2·CH₂Cl₂, 3 and 4 have been determined by single-crystal X-ray diffraction.     

Ruthenium(III)-carbonyl and ruthenium(II)-nitrosyl complexes of nitrogen-containing ligands with ethoxysilane groups

Reactions of γ-aminopropyltriethoxysilane and 4-(diethylamino)salicylaldehyde in ethanol afforded a Schiff base L1H, which reacted with [Ru(CO)₂Cl₂]_n in the presence of Et₃N in THF giving a ruthenium(III) carbonyl complex RuCl(CO)₂(η¹-O-L1)(η²-O,N-L1) (1). Treatment of γ-aminopropyltriethoxysilane with 4-pyridinecarboxaldehyde gave the Schiff base L2. Interactions of L2, γ-aminopropyltriethoxysilane, and Ru(NO)Cl₃?H₂O in THF led to the formation of a ruthenium(II) nitrosyl complex RuCl₃(NO)(L2)[H₂N(CH₂)₃Si(OEt)₃] (2) with linear N≡O ligand. Complexes 1 and 2 were characterized by microanalyses and IR and MS spectroscopies and confirmed by single-crystal X-ray diffraction.     

Syntheses,structures, and properties of seven-coordinate calcium(II) and five-coordinate lead(II) complexes with 1-D structures

Two new 1-D heterometallic coordination polymers (CPs), {[Ca(NiL)(H₂O)₄]?·?3H₂O} _n (1) and {[Pb(NiL)(H₂O)₂]?·?3H₂O)} _n (2), have been prepared by reactions of CaCl₂ and NiL and Pb(NO₃)₂ and NiL in CH₂Cl₂–H₂O. H₂L denotes dimethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo-9,10-benzo-[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Single-crystal X-ray diffraction studies show that the coordination geometries around Ni(II) in both 1 and 2 are similar distorted N₄ square planar. All Ni–N bonds are short. Complex 1 has 1-D zigzag chain, while 2 shows 1-D “head-to-tail” structure. In crystals 1 and 2, 1-D CP chains were parallel-packed and 3-D supramolecular networks were formed via weak hydrogen bond interactions between aqua ligands and lattice water. The effects of water on the assemblies of the two CPs are discussed. Coordinated water plays an important role on the assembly procedure.     

Syntheses and crystal structures of three copper(II) complexes with bulky Schiff bases derived from rimantadine

The reactions of copper(II) chloride dihydrate and three bulky Schiff base ligands derived from rimantadine and salicylaldehyde (or methoxy-substituted salicylaldehydes), generated C₃₈H₄₈CuN₂O₂ (1), C₄₀H₅₂CuN₂O₄ (2), and C₄₀H₅₂CuN₂O₄ (3), respectively. These complexes were characterized by infrared spectra, UV–vis, elemental analysis and molar conductance. X-ray single-crystal diffraction analysis reveals that 1 has two different spatial configurations, 1a and 1b. For 1a, each asymmetric unit consists of one mononuclear copper(II) molecule. For 1b, each asymmetric unit consists of two copper(II) mononuclear molecules. All the complexes crystallize in the monoclinic system, P2₁/c space group for 1a and 2; P2₁/n space group for 1b; C2/c space group for 3. Each complex for 1–3 consists of one copper(II) and two corresponding deprotonated ligands. The central copper(II) in all complexes is four-coordinate via two nitrogens and two oxygens from the corresponding Schiff base ligands. The geometry around copper in 1a, 1b, and 2 is distorted square planar, but square planar in 3.     

Copper(II) complexes of symmetrical and unsymmetrical tetradentate Schiff base ligands incorporating 1-benzoylacetone: Synthesis,crystal structures and electrochemical behavior

Three new copper(II) complexes [CuL¹]₂(ClO₄)₂ (1), [CuL²]ClO₄ (2) and [CuL³] (3) with three Schiff base ligands [HL¹ = 1-phenyl-3-{3-[(pyridin-2-ylmethylene)-amino]-propylimino}-butan-1-one, HL² = 1-phenyl-3-[3-(1-pyridin-2-yl-ethylideneamino)-propylimino]-butan-1-one and H₂L³ = 3-[3-(1-methyl-3-oxo-3-phenyl-propylideneamino)-propylimino]-1-phenyl-butan-1-one] have been synthesized and structurally characterized by X-ray crystallography. The mono-negative tetradentate asymmetric Schiff base ligands (L¹)⁻ and (L²)⁻ are chelated in complexes 1 and 2 to form square planar copper(II) complexes. In complex 1, the two units are associated weakly through ketonic oxygen of benzoylacetone fragment to form the dimeric entity. The square planar geometry of complex 3 is unusually distorted towards tetrahedral one. All three complexes exhibit reversible cyclic voltammetric responses in acetonitrile solution corresponding to the Cu^II/Cu^I redox process. The E_1/2 (−0.47 V versus SCE) of 3 shows significant anodic shift due to the tetrahedral distortion around Cu(II) compare to that of 1 and 2 (−0.82 and −0.87 V versus SCE, respectively).     

Synthesis,spectral, electrochemical and catalytic studies of new Ru(III) tetradentate Schiff base complexes

The synthesis and characterization of several hexa‐coordinated ruthenium(III) Schiff base complexes of the type [RuX(EPh₃)(L)] (X = Cl or Br; E = P or As; L = dianion of the tetradentate Schiff base) are reported. IR, EPR, electronic spectra and cyclic voltammetric data of the complexes are discussed. An octahedral geometry has been tentatively proposed for all of these complexes. The new complexes have been subjected to catalytic activity in the reaction of oxidation of alcohols in the presence of N‐methylmorpholine‐N‐oxide. Copyright © 2007 John Wiley & Sons, Ltd.     

Nickel(II) and copper(II) complexes of unsymmetrical tetradentate reduced Schiff base ligands

Two new reduced Schiff base ligands, [HL¹ = 4-{2-[(pyridin-2-ylmethyl)-amino]-ethylimino}-pentan-2-one and HL² = 4-[2-(1-pyridin-2-yl-ethylamino)-ethylimino]-pentan-2-one] have been prepared by reduction of the corresponding tetradentate unsymmetrical Schiff bases derived from 1:1: 1 condensation of 1,2-ethanediamine, acetylacetone and pyridine-2-carboxaldehyde/2-acetyl pyridine. Four complexes, [Ni(L¹)]ClO₄ (1), [Cu(L¹)]ClO₄ (2), [Ni(L²)]ClO₄ (3), and [Cu(L²)]ClO₄ (4) with these two reduced Schiff base ligands have been synthesized and structurally characterized by X-ray crystallography. The mono-negative ligands L¹ and L² are chelated in all four complexes through the four donor atoms to form square planar nickel(II) and copper(II) complexes. Structures of 3 and 4 reveal that enantiomeric pairs are crystallized together with opposite chirality in the nitrogen and carbon atoms. The two Cu^II complexes (2 and 4) exhibit both irreversible reductive (Cu^II/Cu^I; E_pc, −1.00 and −1.04 V) and oxidative (Cu^II/Cu^III; E_pa, +1.22 and +1.17 V, respectively) responses in cyclic voltammetry. The electrochemically generated Cu^I species for both the complexes are unstable and undergo disproportionation.     

Syntheses,crystal structures,and antibacterial activities of manganese(III), nickel(II), and copper(II) complexes containing a tetradentate Schiff base

Three new mononuclear Schiff-base complexes, namely [Mn(L)Cl] (1), [Ni(L)] (2), and [Cu(L)] (3), where L?=?anion of [N,N′-bis(2-hydroxybenzophenylidene)]propane-1,2-diamine, have been synthesized by reacting equimolar amounts of the respective metal chloride and the tetradentate Schiff base, H₂L, in methanol. The complexes have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction, and other physicochemical studies. Structural studies reveal that 1 adopts a distorted square-pyramidal geometry whereas 2 and 3 are isotypic with distorted square-planar geometries. The antibacterial activities of 1–3 along with their Schiff base have been tested against some Gram(+) and Gram(?) bacteria.     

Synthesis, characterization, and X-ray structural analysis of some half-sandwich ruthenium(II) arene complexes with new N,S-donor Schiff base ligands

A series of cationic, half-sandwich ruthenium complexes with the general formula [(η⁶-arene)RuCl(R¹S-C₆H₄-2-CHNR²)]⁺ (arene = p-cymene or hexamethylbenzene; R¹ = CH₂Ph, ⁱPr, or Et; R² = aryl) have been prepared from the reaction of [(η⁶-arene)RuCl₂]₂ with various N,S-donor Schiff base ligands derived from 2-(alkylthio)benzaldehyde and several primary amines. All of the ruthenium complexes were characterized by IR, ¹H NMR, electrochemistry, and UV/Vis spectroscopies. The p-cymene complexes undergo irreversible oxidations while the hexamethylbenzene complexes undergo quasi-reversible oxidations. The molecular structures of ligand 1a and complexes 4a, 4l, and 5e were determined by X-ray crystallography.     

Syntheses and crystal structures of two Schiff-base copper(II) complexes with urease inhibition

Two new copper(II) complexes, [CuL1(N₃)] (1) and [CuL2(NCS)] (2) (HL1 = 4-chloro-2-[(2-piperidin-1-ylethylimino)methyl]phenol, HL2 = 4-chloro-2-[(2-morpholin-4-ylethylimino)methyl]phenol), were prepared and structurally characterized by elemental analyses, infrared spectroscopy, and single-crystal X-ray diffraction. Complex 1 is an azide coordinated mononuclear complex, while complex 2 is a terminal thiocyanate coordinated mononuclear complex. The coppers in both complexes are four-coordinate, square-planar. Both complexes show potent urease inhibitory properties.     

The crystal structures and electrochemical studies of two naphthalenic Schiff base copper(II) complexes

The Schiff base ligands, 2-hydroxy-N-cyclohexyl-l-naphthaldimine (I), and 3-hydroxy-N-cyclohexyl-2-naphthaldimine (II), and their corresponding Cu^II complexes (1–2) respectively were synthesized and characterized. The crystal and molecular structures of bis-{(cyclohexyl)[(2-oxo-1H-naphth-1-ylidene)-methyl]aminato}copper(II) (1) and bis-{(cyclohexyl)[(3-oxo-2H-naphth-2-ylidene)-methyl]aminato} copper(II) (2), were determined. The X-ray diffraction study shows that the geometry around the metal atom for (1), is stepped square planar with a step of 1.063 Å while for (2), the geometry around the metal atom for square planar with an angle between the coordination planes O(1)---Cu---N(1) and O(1a)---Cu---N(1a) of 39.9°. Electrochemical studies show a dependence of the Cu^II/Cu^I potentials on the ligand structure.     

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     

Syntheses,structures and catalytic properties of new mononuclear terpyridine-manganese(II) complexes with tetraphenylimido-diphosphinate and diphenylphosphinate ligands

Treatment of manganese(II) acetate tetrahydrate [Mn(CH3COO)₂·4H₂O] with one equivalent of 2,2′:6′,2′′-terpyridine (terpy) and two equivalents of potassium tetraphenylimido-diphosphinate K[N(Ph₂PO)₂] in methanol afforded a mononuclear manganese(II) complex, [(terpy)Mn{η¹-O-N(Ph₂PO)₂}₂(H₂O)] (1), with two terminal [N(Ph₂PO)₂]– ligands. Interaction of [Mn(CH₃COO)₂·4H₂O] with one equivalent of terpy in the presence of both K[N(Ph₂PO)₂] and Ph₂PO₂K in methanol gave a mononuclear manganese(II) complex [(terpy)Mn(η¹-O-O₂PPh₂){N(Ph₂PO)₂}] (2) with a chelated [N(Ph₂PO)₂]– ligand. Treatment of manganese(II) dichloride tetrahydrate [MnCl₂·4H₂O] with three equivalents of K[N(Ph₂PO)₂] in methanol resulted in isolation of a mononuclear manganese(III) complex [Mn{η¹-O-N(Ph₂PO)₂}-{N(Ph₂PO)₂}₂] (3) with one terminal and two chelated [N(Ph₂PO)₂]– ligands. Reaction of [Mn(CH₃COO)₂·4H₂O] with one equivalent of 4′-phenyl-[2,2′:6′,2′′]-terpyridine (4-Ph-terpy) and two equivalents of Ph₂PO₂K in methanol gave [(4-Ph-terpy)Mn(η¹-O-O₂PPh₂)₂(H₂O)] (4) with a labile water molecule. Complexes 1–4 have been spectroscopically characterized and their structures have been established by single-crystal X-ray diffraction. Catalytic behavior of 1 and 4 for sulfide oxidation was also investigated.     

Electrochemical behaviour of a series of Fe(III) complexes with tetradentate Schiff base ligands

Summary The electrochemical reduction of the Fe(III) complexes with a series of substituted N,N-Ethylenebisacetonimines was investigated by cyclic voltammetry in acetonitrile solution at a platinum electrode. The substituent does not significantly influence the redox properties of the studied complexes. The symmetry of the redox orbital is responsible for the observed behaviour of the complexes.

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Elektrochemisches Verhalten einer Reihe von Fe(III)-Komplexen mit vierzähnigen Schiffschen Basen als Liganden

Zusammenfassung Die elektrochemische Reduktion der Fe(III)-Komplexe einer Reihe von substituierten N,N-Ethylenbisacetoniminen wurde mittels cyclischer Voltammetrie in Acetonitril an einer Platinelektrode untersucht. Der Substituent beeinflußt die Redoxeigenschaften der untersuchten Komplexe nicht signifikant. Das beobachtete Verhalten der Komplexe wird von der Symmetrie des Redoxorbitals bestimmt.

     

Syntheses,characterization and X-ray crystal structures of Ni(II) complexes of tridentate monocondensed and tetradentate dicondensed Schiff bases

Two octahedral complexes [Ni(HL¹)₂](ClO₄)₂ (1) and [Ni(HL²)₂](ClO₄)₂ (2) and a square planar complex [Ni(HL³)]ClO₄ (3) have been prepared, where [HL¹ = 3-(2-amino-ethylimino)-butan-2-one oxime, HL² = 3-(2-amino-propylimino)butan-2-one oxime] and H₂L³ = 3-[2-(3-hydroxy-1-methyl-but-2-enylideneamino)-1-methyl-ethylimino]-butan-2-one oxime. All the complexes have been characterized by elemental analyses, spectral studies and room temperature magnetic moment measurements. The molecular structures of all three compounds were elucidated on the basis of X-ray crystallography; complexes 1 and 2 are seen to be the mer isomers.     

Synthesis,characterization, crystal structure,and electrochemical properties of three copper(II) complexes with 3,5-dihalosalicylaldehyde Schiff bases derived from amantadine

Abstract

Complexes 1-3, C₃₄H₃₆X₄CuN₂O₂ (X?=?Cl, Br, I), were synthesized with copper chloride dihydrate and three new Schiff base ligands derived from amantadine and 3,5-dihalosalicylaldehydes. They were characterized by IR, UV–VIS, elemental analysis, molar conductance, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that 1 and 2 crystallize in the triclinic system, Pī space group. Each asymmetric unit consists of one copper(II) ion, two corresponding deprotonated Schiff base ligands and one lattice dichloromethane molecule. 3 crystallizes in the monoclinic system, P2₁/n space group. Each asymmetric unit consists of one copper(II) ion and two deprotonated iodo- Schiff base ligands. The tetra-coordination of the central copper(II) ion in 1-3 is constructed by two nitrogen atoms and two oxygen atoms from the corresponding Schiff base ligands, forming a distorted tetrahedral geometry. Electrochemical properties of the complexes were determined by cyclic voltammetry.

     

ESCA OF TETRAAZA MACROCYCLIC COMPLEXES OF SILVER(II)

Abstract

ESCA results for four tetraaza macrocyclic ligands and their silver(II) complexes have been measured. The Ag 3d binding energies of these complexes fall in the narrow range of 374.3–375.3 eV (3d_3/2) and 368.2–375.3 eV (3d_3/2) and 368.2–369.3 eV (3d_5/2) which are in agreement with the E_b values published previously for silver(II) complexes containing nitrogen donor ligands. Ring substitution with methyl groups has no pronounced influence on the Ag 3d, binding energies while ring size variation does cause a small shift in the binding energies. Ring strain energy is invoked as the probable reason for the observed effect.     

Schiff base complexes of ruthenium(II) with tridentateN-methyl-S-methyldithiocarbazate ligands

Summary Schiff bases (HL) produced by the condensation ofN-methyl-S-methyldithiocarbazate with -diketones and aromatic aldehydes or ketones react with [RuHClCO(PPh₃)₃] to yield hexacoordinated complexes of the type [RuClCO(PPh₃)₂(L)]. These Schiff bases react with [RuCl₂{P(OR)₃}₄] in 11 molar ratio to yield [RuCl{P(OR)₃}₂(L)] in which L is a tridentate. The chlorine atom in the complex can be removed in coordinating solvents in the presence of anions such as [BPh₄]^– to give cationic complexes. Bis chelate complexes, [Ru{P(OR)₃}₂(L)₂] are prepared from 12 molar proportions of the reactants. These complexes were characterised by elemental analyses, i.r.,¹H n.m.r., u.v. and conductivity studies.NCL Communication No. 4224.     

Syntheses,crystal structure and biological evaluation of three novel Cu (II) complexes with Schiff base derived from fluorinated amino acid and Salicylaldehyde

Three novel Cu (II) coordination complexes, formulated as [Cu₃(C₁₄H₈NO₃F) ₂ (CH₃COO)₂]_n ( 1 ), [Cu₂(C₁₄H₉NO₃F)₂(CH₃COO)Cl] ( 2 ) and [Cu(C₁₄H₈NO₃F)(CH₃OH)₂] ( 3 ), have been synthesized by 3-Fluoroanthranilic acid, Salicylaldehyde and Cu (II) salt as sources in different reaction conditions and characterized by single crystal X-ray diffraction, X-ray powder diffraction, IR spectroscopy and elemental analysis. Single-crystal diffraction analysis revealed that the complexes exhibited different coordination modes and conformations which were linked into multidimensional networks through some weak interactions. The biological activities vary greatly on account of the different Cu (II) numbers among the three complexes. In order to discuss the bioactivities, the complexes have been screened for antimicrobial activities against E. coli and S. aureus, antitumor activities against A549 (human lung cancer cells), Hela (human cervical cancer cells) and HepG-2(human liver hepatocellular carcinoma cells). Their interactions with calf thymus DNA were investigated by UV–visible and fluorescence spectrometry, as well as viscosity measurements. Interestingly, 1 (the rare 3-core Cu (II) coordination polymer) shows great antibacterial activities and highest DNA binding affinities. Antitumor studies revealed that complex 1 also exhibited highest activity.