Preparation and characterization of copper(II) and nickel(II) complexes with novel tetraaza-macrocyclic schiff bases

Novel tetraaza-macrocycles with N-substituted carbamoyl groups were prepared by the reaction of 5,7,12,14-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,5,7,12-tetraene with isocyanates (RNCO, R = Ch₃ and C₆H₅). Their copper(II) and nickel(II) complexes were characterized by magnetic susceptibilities, electronic absorption spectra, and electrochemical properties. The complexing abilities and extractabilities of the ligands for the metal ions were investigated.     

Salen and tetrahydrosalen nickel(II) and copper(II) complexes

The synthesis and characterisation of novel bis salen complexes, M(salenH2), N,N-bis-[5(1,1,3,3-tetramethyl- butyl)salicylidene]-1,2-diaminoethane complexes, (M=Ni or Cu), and the corresponding less studied, bis-tetrahydrosalen complexes, M[H2(salenH2)], N,N-bis-[2-hydroxy-5(1,1,3,3-tetramethylbutyl)benzyl]-1,2-diaminoethane complexes, (M=Ni or Cu), with a highly branched substitution pattern at C-5 of the benzene ring is described. The Schiff bases behave as dibasic tetradentate ligands. The tetrahydrosalen complexes show structural properties, chemical and thermal behaviour which is different from those of the corresponding salen complexes. The melting points and decomposition temperatures of these complexes were determined by d.s.c. and t.g.a.     

Synthesis of copper(II) and nickel(II) triazacycloalkane complexes

Summary Copper(II) and nickel(II) complexes of triazacycloalkanes (pqr-cy), with p, q, r = 2–6, have been prepared and characterized by means of electronic and i.r. spectroscopy, and by magnetic measurements. With nickel(II) mononuclear octahedral complexes [Ni(pgr-cy)₂](CI0₄)₂ are formed, but for copper(II) mononuclear octahedral complexes were obtained only for 222-cy and 223-cy. The other ligands gave copper(II) complexes of the type [Cu(pgr-cy)CI]CIO₄, [Cu(pgr-cy)OH]ClO₄, Or [Cu(pgr-cy)CI_1/2OH_1/2]ClO₄. The hydroxy complexes have low magnetic moments and binuclear hydroxy bridged structures are proposed.Ligand names: e.g. p = q = r = 2 is 1,4,7-triazacvclononane     

Preparation and characterization of mononuclear nickel(II) and copper(II) complexes of a hexaazamacrobicyclic ligand

Summary The structure of the hexaazamacrobicycle, sarcophagine, (diAMMEsar)·2H₂O, formed by extracting Co ion from the [Co(diAMMEsar H₂)]Cl₅·-H₂O cage with 8-hydroxyquinoline, has been determined by elemental analysis, and i.r., u.v.-vis., ¹H-n.m.r. and mass spectroscopies. Two octahedral complexes, [M(diAMM-EsarH₂)]Cl₄·2H₂O (M = Ni^II or Cu^II), have been prepared and characterized. The e.s.r. spectrum of the Cu^II complex in the solid state indicates spin-exchange interaction between the Cu^II ions. However, in CD₃OD-D₂O (10%) at 77K, the spectrum is characteristic of a compound having axial symmetry (d _x ²−y ²).     

Synthesis and properties of nickel(II) and copper(II) complexes of a di-N-acetamide tetraaza macrocycle

The syntheses of the hexadentate ligand 2,13-bis(acetamido)-5,16-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane (L²) and its complexes with Ni(II) and Cu(II) are described. Crystal structures of H₂L²·2HClO₄ (1), [Ni(L²)](ClO₄)₂ (2) and [Cu(L²)](ClO₄)₂ (3) are reported. The two pendant acetamide groups of the macrocyclic ligand 1 are trans to each other and the absolute configuration is a trans-IV in the solid state. The crystal structures of 2 and 3 revealed an axially elongated octahedral geometry with four nitrogen atoms of the macrocycle and two oxygen atoms of the pendant acetamide groups at the axial positions. The nickel(II) and copper(II) ions are located at an inversion center. The electronic spectra and electrochemical behaviors of the complexes are significantly affected by the presence of the pendant arms.     

Cobalt(II), nickel(II) and copper(II) with 2-substituted benzimidazole complexes

Summary Complexes of stoichiometries M(Acbim)₂X₂·nH₂O and M(Bzbim)₂X₂·nH₂O (M = Co, Ni or Cu; Acbim = 2-acetylbenzimidazole, Bzbim = 2-benzoylbenzimidazole; X = Cl, Br, NO₃ or ClO₄; n = 0, 1 or 2) have been prepared and characterised by spectroscopic and physicochemical methods. The ligands coordinate through carbonyl oxygen and tertiary nitrogen.     

2-thiouracil-based cobalt(II), nickel(II) and copper(II) complexes

Summary Cobalt(II), nickel(II) and copper(II) complexes of 2-thiouracil and its arylazo derivatives were prepared. The elemental analysis suggest a range of 11, 21 and 13 stoichiometries. Electronic spectra and magnetic susceptibility measurements were used to infer the structures and the i.r. spectra of the ligands and their complexes to identify the type of bonding.     

Protolytic properties of 8-quinolylhydrazones of substituted salicylaldehydes and physicochemical properties of their copper(II) complexes

Acid-base properties of hydrazones derived from 8-hydrazinoquinoline and substituted salicylaldehydes were studied. Under the experimental conditions, only the first step of ionization of the hydrazones is realized. The ionization constants were calculated quantum-chemically. Copper(II) complexes of these hydrazones, (HL)Cu(X)(CH₃OH)_n, were isolated (HL^? is the monodeprotonated form of hydrazones, and X^? is the acid residue). According to the data of elemental analysis, IR spectroscopy, conductometry, and magnetochemistry, the majority of the complexes have a binuclear structure. The copper(II) ions in the dimeric complex show antiferromagnetic exchange coupling. The ionization constants of the hydrazones and the exchange parameters strongly depend on the substituent in the salicylaldehyde moiety.     

Cobalt(II), nickel(II) and copper(II) complexes of bidentate bibenzimidazoles

Summary Complexes of cobalt(II), nickel(II) and copper(II) with novel bidentate bibenzimidazoles, [M(L-L)Cl₂], where L-L are methylenebis(1, 1-benzimidazole), methylenebis(2, 2-benzimidazole) and dimethylenebis(2, 2-benzimidazole) are described and characterized by different physical measurements. The four coordinate complexes have distorted tetrahedral or square coplanar structures. The bridging entity between the two donor groups apparently influences the ligand field strength and the ligands occupy a higher position than that of benzimidazole in the spectrochemical series.     

Synthesis,crystal structures and physical properties of two terephthalate-bridged copper(II) and nickel(II) complexes

Two ₂-terephthalate (tp) bridged complexes, [Cu₂(tp)(pren)₄](ClO₄)₂ (pren = 1,3-diaminopropane) (1) and [Ni₂(tp)(pren)₄(Him)₂](ClO₄)₂ (Him = imidazole) (2), have been synthesized and characterized by X-ray single-crystal structural analysis. In the discrete dinuclear [Cu₂(tp)(pren)₄]²⁺ cation of complex (1), each Cu^II atom has a square-pyramidal geometry, being coordinated by four nitrogen atoms (avg. 2.031 Å) from two pren ligands at the basal plane and one oxygen atom [2.259(3) Å] from a bis-monodentate tp group at the axial position. In the discrete dinuclear [Ni₂(tp)(pren)₄(Him)₂]²⁺ cation of complex (2), each Ni^II center is coordinated by five nitrogen atoms [Ni—N 2.069(3)–2.109(2) Å] from one Him group and two pren groups, and completed by one oxygen atom [Ni—O 2.138(3) Å] from a bis-monodentate tp group to furnish a distorted octahedron. Magnetic susceptibility studies show that the pair of metal atoms, although being separated by >11.5 Å, exhibit weak intramolecular antiferromagnetic interactions in complexes (1) (g = 2.07 and J = –3.4 cm^–1) and (2) (g = 2.10 and J = –0.7 cm^–1). The electrochemical behaviors of the complexes have also been studied by cyclic voltammogram processes.     

Preparation of some nickel(II) and copper(II) complexes of the SCHIFF-Base derived from Acetophenone and Ethylenediamine

Preparation and properties of the following Ni^II and Cu^II complexes of the Schiff base derived from acetophenone and ethylenediamine (BAPE) and also of the mixed Ni^II and Cu^II chelates with BAPE and acetylacetone (acac-H) are described: In each case the Schiff base, BAPE, acts as a neutral bidentate ligand. The complexes are characterised by electronic spectra, magnetic susceptibilities, conductivities and elemental analyses. Pseudotetrahedral structure is proposed for M(BAPE)C1₂, while tetragonal structure for [M(BAPE)(acac)(H₂O)₂]C_lO₄ (M = Ni and Cu). The complex [Ni(BAPE) (acac)]ClO₄ has been found to be square planar.     

Synthesis,spectral and magnetic properties of binuclear copper(II)/nickel(II) and copper(II) complexes bridged by glyoximate groups

Three new dinuclear complexes, [(tmen) (H2O)2Ni (Hdmg)(dmg)Cu]·ClO4, [(dien)(H2O)Ni (Hdmg)(dmg) Cu]·ClO4 and [(tmen)Cu(Hdmg)(dmg) Cu] ClO4·H2O (H2dmg=dimethylglyoxime, tmen=tetramethylene diamine), have been prepared. Variable-temperature- magnetic susceptibility measurements (75–300K) on the complexes reveal the presence of intramolecular antiferromagnetic interactions through the oximate bridges. The formation of mononuclear, dinuclear complexes has been confirmed by spectrophotometry.     

Zinc(II) halide and copper(II) bromide complexes with caffeine: structures,physicochemical properties,and biological activity

Russian Chemical Bulletin - This study provides a comparative characterization of the structural parameters and cytotoxicity of zinc halide and copper(II) bromide complexes with caffeine (caf) of...     

QSAR of copper(II) complexes with cytotoxic properties

Summary A QSAR based on a multiple regression analysis for 15 copper(II) semi- and thiosemicarbazone complexes with cytotoxic properties is presented. In vitro cytotoxicity was selected as the dependent variable and Van der Waals volumes (Vm), octanol- water partition coefficients (logP), specific rate constants of the copper(II) complexes towards superoxide radicals (k _s ) and variation in C=N vibration bands (CN) in IR spectra of the complexes with respect to the free ligands were selected as the independent variables. The stepwise regression procedure and the all possible regressions were practiced in the analysis of the data. The orthogonality analysis proved noncollinearity among the variables. According to the obtained equation the two best copper(II) complexes were submitted to a broad in vivo screening study and resulted to be active against La, P-388 and L-1210 leukemias.

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QSAR von Kupfer(II)-Komplexen mit cytotoxischen Eigenschaften

Zusammenfassung Es wird eine quantitative Struktur-Aktivitäts-Beziehung basierend auf einer multiplen Regressionsanalyse für 18 Kupfer(II)-Semi- und Thiosemicarbazon-Komplexe präsentiert. Die in vitro-Cytotoxizität wurde als die abhängige Variable und Van-der-Waals-Volumina (Vm), Octanol-Wasser-Verteilungskoeffizienten (logP), spezifische Geschwindigkeitskonstanten der Kupfer(II)-Komplexe gegenüber Superoxid-Radikalen (k _s ) und die Variationen der C=N-Vibrationsbanden (CN) in den IR-Spektren der Komplexe gegenüber den freien Liganden als unabhängige Variablen eingeführt. Es wurde stufenweise Regression und die alle möglichen Regressionen-Prozedur in der Analyse der Daten verwendet. Die Orthogonalitätsanalyse zeigte Nichtkolinearität der Variablen an. Entsprechend den erhaltenen Gleichungen wurden die beiden besten Kupfer(II)-Komplexe einem breiten in vivo-Screening unterworfen. Sie waren gegenüber La, P-388 und L-1210 Leukemie aktiv.

     

Ferromagnetic coupling of copper(II) and nickel(II) complexes with a cyclam-based paramagnetic host

Bis(NN–CH₂)-substituted dimethylcyclam (cyclamNN₂) was designed and synthesized as a paramagnetic host, where NN stands for 4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide. We prepared transition-metal complexes [M(cyclamNN₂)](ClO₄)₂ (M = Cu (1), Ni (2)) and investigated their metal–radial exchange couplings. The copper ion in 1 is located at the center of the cyclam cavity and one radical arm is coordinated at an axial position. Compound 1 showed ferromagnetic coupling (2J/k_B = +44(3) K), which is ascribable to the NN–Cu coupling. Ferromagnetic coupling was also observed in 2, but the molecular structure was unknown at present. The Curie–Weiss analysis gave the Weiss temperature (θ) of +13.5(6) K for 2.     

Substituent effects of beta-diketiminate ligands on the structure and physicochemical properties of copper(II) complexes

Substituent effects of beta-diketiminate ligands on the structure and physicochemical properties of the copper(II) complexes have been systematically investigated by using 3-iminopropenylamine derivatives R1LR3H, R3-N=CH-C(R1)=CH-NH-R3, where R1 is Me, H, CN, or NO2, and R3 is Ph, Mes (mesityl), Dep (2,6-diethylphenyl), Dipp (2,6-diisopropylphenyl), or Dtbp (3,5-di-tert-butylphenyl). When the ligands with R3=Ph or Dtbp were treated with CuII(OAc)2, bis(beta-diketiminate) copper(II) complexes exhibiting distorted tetrahedral geometries were obtained, the crystal structures of which were nearly the same as each other regardless of the alpha-substituent (R1); dihedral angles between the two beta-diketiminate coordination planes are 62.5 +/- 1.2 degrees, and the Cu-N bond lengths are 1.959 +/- 0.008 A. The distorted tetrahedral structures are maintained in solution, but the spectroscopic features, especially gII values of the ESR spectra and the d-d bands of the absorption spectra, as well as the electrochemical behaviors of the complexes, are significantly affected by the electronic nature of R1. The ligands with R3=Mes and Dep, on the other hand, gave di(mu-hydroxo)dicopper(II) complexes, and their crystal structures as well as spectroscopic and electrochemical features have also been explored. Furthermore, the ligand with the more sterically encumbered aromatic substituent (Dipp) provided a mononuclear four-coordinate square planar copper(II) complex supported by one beta-diketiminate ligand and one didentate acetate ion. Thus, the beta-diketiminate ligands with a variety of substituents (R1 and R3) have been explored to provide coordinatively unsaturated (four-coordinate) mononuclear and dinuclear copper(II) complexes with significantly different coordination geometry and properties.     

Synthesis,spectroscopy and thermal properties of the nickel(II), palladium(II) and copper(II) complexes of oxalyldihydrazide

Summary The new complexes K₂[ML₂]·2H₂O (M=Ni, Cu), K₂[PdL₂]·H₂O, K₂[CuL₂(H₂O)₂]·H₂O, [Ni(LH₂)Cl₂]_x ·xH₂O and [Ni(LH₂)Br₂]_x·1,5xH₂O, where LH₂= oxalyldihydrazide, have been prepared. Emphasis has been put on determining the conditions for the synthesis of both deprotonated and non-deprotonated Ni^II complexes. They were characterized by analyses, conductivity measurements, thermogravimetry, magnetic susceptibility and spectroscopic methods like i.r. and far-i.r., diffuse reflectance u.v. vis, and e.s.r. Monomeric square planar and distorted octahedral structures were found for the deprotonated complexes in the solid state while the non-deprotonated Ni^II complexes appeared to be pseudo-tetrahedral polymers. The doubly deprotonated L²-ion exhibits a bidentate N(amide), N(amide)-coordination, while the neutral LH₂ molecule behaves as a N(amino), N(amino)-bidentate ligand forming polymeric structures. Vibrational analysis of the complexes was carried out, using hydrogen and metal isotopic substitution.     

Spectroscopic studies of cobalt(II), nickel(II) and copper(II) complexes with N-ethyl- and N-propylimidazole

The preparations are reported of complexes of the type ML₂X₂, (M = Cu(II), X = Cl, Br, SCN; M = Ni(II), X = SCN: M = Co(II), X = Cl, Br, I, SCN): ML₄X₂(M = Cu(II), X = Cl, Br, N0₃, CIO₄ Bφ₄: M = Ni(II), X = Cl, I, SCN, NO₃; M = Co(II), X = SCN, ClO₄, Bφ₄); ML₆X₂(M = Ni(II), X = Cl, Br, I, NO₃, ClO₄, Bφ₄: M = Co(II), X = Br, NO₃): L = N-ethylimidazole, N-propylimidazole. Magnetic susceptibility, i.r. and electronic spectra, conductivity data in MeOH or EtNO₂ at 25°C are reported and structural information is deduced. The CuL₂X₂ complexes are generally square planar. NiL₂(NCS)₂ and CoL₂X₂ have pseudotetrahedral structure, CoL₄ (ClO₄)₂ are tetrahedral, CuL₄X₂(X = Cl, Br, ClO₄, Bφ₄) ar square, CuL₄(NO₃)₂ square-planar pseudo-octahedral, NiL₄X₂, NiL₆X₂, CoL₄(NCS)₂ and CoL₆X₂ are octahedral.