Complex formation of 1,4,7-tris(β-diphenylphosphinylethyl)-1,4,7-triazacyclononane with divalent copper salts

An investigation of the monoligand complex of 1,4,7-tris(-diphenylphosphinylethyl)-1,4,7-triazacyclononane with divalent copper has been carried out in various solvents using electronic, IR, and ESR spectroscopy. It was found that the five-coordination polyhedron formed in the complex involves only donor atoms of the ligand and has the structure of a tetragonally elongated square pyramid with two nitrogen atoms and two oxygen atoms at the base and a nitrogen atom at the apex. Compared with the copper(II) complex with the corresponding acid, 1,4,7-tris(-dihydroxyphosphinylethyl)-1,4,7-triazacyclononane, the coordination compound studied has a higher order of symmetry. The absence of observable distortions in the case of the acid is probably connected with steric interaction of the bulky phenyl substituents in the test ligand.A. N. Nesmeyanov Institute of Heteroorganic Compounds, Russian Academy of Sciences, Moscow 117813. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 594–601, March, 1992.     

Syntheses and crystal structure of binuclear μ-oxamido copper(II) complexes containing 1,4,7-triazacyclononane as a terminal ligand

Two new binuclear copper(II) complexes, Cu(tacn)Cu(oxpn)(ClO₄)₂·C₂H₅OH (1), and Cu(tacn)Cu(oxap)(ClO₄)₂·CH₃OH (2), have been prepared from the planar fragment Cu(oxpn) and Cu(oxap) (tacn denotes 1,4,7-triazacyclononane, oxpn and oxap stand for the dianions of N,N′-bis(3-aminopropyl)oxamide, and N,N′-bis(2-aminopropyl)oxamide, respectively). The complexes have been characterized by means of elemental analyses and IR, and UV spectra. The crystal structure of compound 1 shows that copper(II) coordinates to the four nitrogen atoms of oxpn in a square-planar environment and the other copper(II) ion is in a distorted square-pyramidal environment.     

Coordination chemistry of 1,4-bis(carboxymethyl)-1,4,7-triazacyclononane: Synthesis and characterization of mononuclear and binuclear μ-oxo-bridged iron(III) complexes,and a 1D-helical copper(II) chain

The syntheses of the pentadentate ligand 1,4-bis(carboxymethyl)-1,4,7-triazacyclononane (LH₂) and its use in the preparation of [LHCu]ClO₄ (1), and a mononuclear iron(III) complex ([LFeCl] (2)) are reported. The hydrolysis of 2 in the presence of an excess of NaClO₄ resulted in the crystallization of a binuclear complex, [Fe₂(μ-O)L₂] · (NaClO₄)₃ · CH₃OH · 3H₂O (3). The crystal structures of 1–3 have been determined by single-crystal X-ray crystallography. In complex 1, the Cu(II) centre is in square based pyramidal environment, with two nitrogen atoms from the tacn ring and two oxygen atoms from two different carboxylate groups lying in the basal plane and the third nitrogen atom occupying the apical position. One pendant acetic acid group is protonated and, instead of coordinating to the copper(II) centre, participates in hydrogen bonding interactions with the perchlorate counter-ion. The coordinated carboxylate group forms a bridge to the copper atom of an adjacent [LHCu]⁺ molecule, thus generating 1D-helical chains. The compound exhibits weak ferromagnetic coupling probably due to weak interactions between [LHCu]⁺ molecules. In complex 2, the iron(III) centre is in a distorted octahedral geometry, with the fac-coordinated triamine ring, two carboxylate groups and one chloride ligand occupying the coordination sphere. In the binuclear complex 3, two iron(III) centres are bridged by one oxygen atom to form a μ-oxo-diiron(III) complex with an Fe?Fe distance of 3.423(3) Å and a non-linear Fe–O–Fe angle of 144.4°. This binuclear complex features strong antiferromagnetic coupling between the two iron(III) centres.     

Novel trinuclear copper(II) complexes with α,β-unsaturated carboxylates and imidazole

A MeOH solution of imidazole reacts with Cu₂A₄(H₂O)₂ [A = CH₂=CHCO^– ₂, CH₂=C(Me)CO^– ₂] to yield novel trinuclear copper(II) carboxylate complexes of general formula: Cu₃A₅(OH)(imH)₃ [(1) A=CH₂=CHCO^– ₂; (2) A = CH₂=C(Me)CO^– ₂; imH = imidazole]. The crystal structure of (2) has been determined. The geometry of one copper(II) atom is distorted trigonal bipyramidal, and the other two copper(II) atoms are distorted square-planar. The i.r. spectra show the presence of the absorption bands of both bidentate ₂-O,O and monodentate carboxylate ligands. The electronic reflectance spectra in the solid state suggest that the d–d transitions of complexes are in a trigonal bipyramidal ligand field and a square-planar ligand field. Room temperature X-band e.s.r. spectra of powdered samples with g _av = 2.140 for (1) and g _av = 2.092 for (2), indicate that there is no spin coupling between the copper(II) atoms.     

2,4′-Bipyridyl complexes with silver(I) and copper(II)

Summary Ag^I and Cu^II complexes with 2,4-bipyridyl (2,4-bipy or L) with the general formulae AgL₂X (where X = NO _inf3 ^sup– or ClO₄ ^-), CuL₂X₂·2H₂O (X = Cl^- or Br^-), CuL₄SO₄·4H₂O, CuL₄(NO₃)₂·2H₂O and CuL₄(ClO₄)₂·H₂O have been isolated pure and characterized by analytical, spectral and magnetic measurements. The thermal decomposition of these complexes was studied under non-isothermal conditions in air.     

Synthesis,characterisation and electrochemical study of 4,4′-bis(salicylideneimino) diphenylethane and its complexes with cobalt(II), copper(II) and cadmium(II)

We have prepared and characterised a new series of metal complexes obtained from 4,4-bis(salicylideneimino)diphenylethane (saldipH₂) and cobalt(II), copper(II) and cadmium(II) chlorides. In every case, the coordinating atoms are N and O. However, each compound has its own structure:[Co(saldip)]·2 H₂O is monomeric and a mononuclear species, [Cu₂(saldip)₂(H₂O)] is a binuclear complex and finally the cadmium complex is formulated as:[(CdCl₂)₂(saldipH₂)]·CdCl₂. An electrochemical study (cyclic voltammetry) indicates that the reduction, as well as the oxidation, of copper in [Cu₂(saldip)₂(H₂O)] proceeds in two steps. For the reduction of the two other complexes, two steps are indicated out: the first is attributed to the reduction of the metal and the second to the reduction of the coordinated ligands.     

Crystal structure and thermal behaviour of copper(II) and zinc(II) complexes with N-pyrrolidine-N′-(2-chloro-benzoyl)thiourea

The crystal structures and thermal behaviour of bis(N-pyrrolidine-N′-(2-chloro-benzoyl)thioureato)zinc(II) (ZnL₂) and its copper(II) analogue (CuL₂) are reported. In both structures, the metal atoms are coordinated by two oxygen and two sulfur atoms to form neutral trans-square planar (Cu) and distorted tetrahedral (Zn) species. The thermal decomposition of the complexes was investigated by TG and DTA.     

Condensation of bis(β-alaninato)copper(II) with formaldehyde and ammonia

Various complexes have been prepared by the template condensation of -amino acids with formaldehyde or acetaldehyde in the presence of metal ions(^1–5). In particular, glycine has received much attention(^1–4). For example, (3N, 7N-1,3,5,7-tetraazabicyclo[3.3.1]nonyl)-diacetato nickel(II) (1) has been prepared by condensing bis(glycinato)nickel(II) dihydrate with formaldehyde and ammonia at pH 8.5⁴. More recently⁵, complex (2) has been prepared by condensing bis(L-alaninato)copper(II) with formaldehyde and ammonia. These reactions are interesting for the following reasons:

Synthesis and spectral characterization of sparteine and α -isosparteine complexes with copper(II) sulfate

Complexes of CuSO₄ of the general formula [Cu(C₁₅H₂₆N₂)SO₄] where [C₁₅H₂₆N₂] is sparteine or α-isosparteine have been obtained from copper(II) and an appropriate alkaloid. The 1?:?1 (metal?:?alkaloid) stoichiometry was confirmed by elemental analysis. The compounds have been characterized by mass spectrometry, IR, and UV–Vis spectroscopy. The magnetic properties were also determined; no anti-ferromagnetic behavior was observed. Information on the geometry of newly obtained compounds was obtained using quantum-chemical calculations.     

Ternary mixed-ligand complexes of copper(II) with α-aminoalkylphosphonic acids and amino acids

Formation of ternary mixed-ligand complexes of copper (II) with 16 -amino acids and -aminophosphonic acids (APA) with a 111 ratio of initial concentrations has been studied by potentiometric titration at 25C and 0.1 M KC1 in aqueous solution. The complexes Cu_pA_nB_sH_q are formed in solution, where A and B are the deprotonated ligands. The stability of the mixed-ligand complexes (log ) increases and the equilibrium is displaced more towards their formation (log K) as the hydrophobic nature of the ligands increases.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 570–575, March, 1991.     

DNA-binding and photocleavage studies of metallofluorescein–porphyrin complexes of zinc(II) and copper(II)

The DNA-binding behaviors of the fluorescein?Cporphyrinatozinc(II) complex Zn(Fl-PPTPP) (Fl-PPTPP?=?5-(4-fluoresceinpropyloxy)phenyl-10,15,20-triphenylporphyrin) and fluorescein?Cporphyrinatocopper(II) complex Cu(Fl-PPTPP) with calf thymus DNA (CT-DNA) were investigated by UV?CVis absorption titrations, fluorescence spectra, viscosity measurements, thermal denaturation and circular dichroism. The results suggest that both complexes interact with CT-DNA by intercalation. In addition, their photocleavage reactions with pBR322 supercoiled plasmid DNA were investigated. Both complexes exhibit significant DNA cleavage activity, and singlet oxygen may play an important role in these reactions.     

Binuclear complexes of copper(II) with 1′-phthalazinylhydrazones of substituted salicylic aldehydes: Physico-chemical study and quantum-chemical simulation

Binuclear complexes of copper(II) with 1′-phthalazinylhydrazones of substituted salicylic aldehydes have been prepared and studied. Antiferromagnetic exchange interaction between copper(II) ions has been revealed in all the complexes. Taking advantage of quantum-chemical simulation, we have investigated the influence of the complexes structural isomerism on the character of the exchange interaction between the paramagnetic centers. X-ray absorbance spectroscopy afforded the structural parameters of coordination spheres of copper(II) ions; it has been demonstrated that dimerization occurred via the nitrogen atoms of phthalazine fragments.     

The structure and EPR spectra of binuclear copper(II) complexes with acyldihydrazones of β-diketones

The synthesis and structure of binuclear copper(II) complexes with acyldihydrazones of some β-diketones are described. The molecular structure of the copper(II) complex [Cu₂L·4Py] with trifluoroacetylacetone succinyldihydrazone (H₄L) was determined by the single-crystal X-ray analysis. Central atoms are bridged by a chain of seven σ-bonds with a Cu...Cu distance of 8.750 Å. EPR spectra of copper(II) complexes with acyldihydrazones of trifluoroacetylacetone and lower dicarboxylic acids containing from one to four methylene groups in the aliphatic spacer show the seven-line HFS due to spin-spin coupling of unpaired electrons with the two equivalent copper nuclei (g = 2.110, a = (38.5–40.5)⊙10^?4 cm^?1). By extending polymethylene spacer, as well as by modifying starting β-diketone, an exchange interaction between paramagnetic centers is suppressed.     

Spectroscopic and electrochemical study of dinuclear and mononuclear copper complexes with the bidentate ligand of the 2,2′-diquinoline series

The newly synthesized complex (2) of copper(I) chloride with di-n-hexyl 2,2′-biquinoline-4,4′-dicarboxylate (L) was spectroscopically and electrochemically characterized. The X-ray diffraction study showed that the crystals of complex 2 consist of the dinuclear moieties [L₂Cu¹ ₂(μ-Cl)₂] containing Cu₂(μ-Cl)₂ clusters. Spectrophotometric studies and ESI-mass spec-trometric measurements showed that after the dissolution of complex 2 in acetonitrile (AN) and N-methyl-2-pyrrolidone (NMP), the solution contained not only the dinuclear complexes [L₂Cu¹ ₂(μ-Cl)₂] but also [L₂Cu¹]Cl, [LCu¹Cl(Sol)], and [Cu¹Cl(Sol)] (Sol is the solvent). The electrochemical data also confirm the conclusion that bridged dinuclear chloride complex 2 dissociates both in NMP and AN to form the tetrahedral bis-biquinoline complex [L₂Cu¹]Cl. In solutions of complex 2 in alcohols and _N,_N-dimethylformamide (DMF), only [L₂Cu¹]Cl and [Cu¹Cl(Sol)] are present. In EtOH, AN, and DMF, [Cu¹Cl(Sol)] undergoes disproportionation to [Cu¹¹Cl(Sol)] and Cu⁰.     

Interconversion of copper(II) to copper(I): synthesis,characterization of copper(II) and copper(I) 2,2′-biquinoline complexes and their microbiological activity

The complexes [Cu(biq)₂]Cl₂ and [Cu(biq)₂]BF₄·biq (biq?=?2,2′-biquinoline) have been prepared and characterized. The interconversion to copper(I) complex [Cu(biq)₂]BF₄·biq, from [Cu(biq)₂]Cl₂ has been established. The new complexes have been characterized by elemental analysis, conductivity and magnetic measurements, IR, UV-vis and ¹H- and ¹³C-NMR spectroscopy. The X-ray analysis of the complex [Cu(biq)₂]BF₄·biq supports the assumption of the interconversion of copper(II) to copper(I) in this case. The crystal structure shows that geometry around the metal is severely distorted from T_d, and displays many supramolecular motifs incorporating both hydrophobic (aryl···aryl) and hydrophilic (C–H···F) intermolecular interactions. The microbiological activity of the complexes against bacteria and fungi was found to be high against Candida albicans, and slight to moderate against bacteria. The antimicrobial activity of [Cu(biq)₂]BF₄·biq was slightly better than that observed for [Cu(biq)₂]Cl₂ against both bacteria and fungi.     

Spectroscopic and structural properties of complexes of 3,3′-bis(2-benzimidazolyl)-2,2′-bipyridine with copper(I) and silver(I)

The pseudo-tetrahedral complexes [CuL₂]PF₆·7H₂O·CH₃OH (1) and [AgL₂]CF₃SO₃·H₂O (2) (L?=?3,3′-bis(2-benzimidazolyl)-2,2′-bipyridine) have been synthesized and characterized through crystal structure analyses, electrochemistry, and spectroscopic methods. X-ray structural analyses of 1 and 2 indicate that sterically constrained N₄ ligands L are cis and behave as bidentate chelates to a single metal ion in a pseudo-tetrahedral fashion through the benzimidazole. As two benzimidazolyl rings exhibit considerable steric hindrance, the bipyridine unit of L remains uncoordinated. The pseudo-tetrahedral cation [CuL₂]⁺ shows a quasi-reversible Cu^I/Cu^II oxidation–reduction wave in the CV in DMF (counter-ion PF₆^?). The fluorescence titration of L with copper(I), silver(I), and also with pH have been conducted to examine the selectivity. The ligand shows remarkably high selectivity and sensitivity for Ag(I).     

Crystal structures and spectroscopic properties of copper(II)–dipicolinate complexes with benzimidazole ligands

The syntheses, crystal structures and spectroscopic properties of three Cu(II)–dipicolinate complexes with benzimidazole ligands, namely [Cu(bzim)(dipic)(MeOH)] (1), [Cu₂(2-Etbzim)₂(dipic)₂]_n·0.5nH₂O (2) and [Cu₂(2-ⁱPrbzim)₂(dipic)₂]_n (3), where dipic?=?dipicolinate, bzim?=?1-H-benzimidazole, 2-Etbzim?=?2-ethyl-1-H-benzimidazole and 2-iPrbzim?=?2-isopropyl-1-H-benzimidazole, are reported. Crystal structure studies revealed different coordination modes of the dipicolinate ligands; tridentate chelating for monomeric complex 1, and both tridentate chelating and bridging for similar polymeric complexes 2 and 3. Polymers 2 and 3 both contain two units, in which the Cu(II) central atoms Cu1 and Cu2 have different coordination polyhedra. The first unit {Cu(dipic)₂} with Cu1 is connected to the second via two bidentate carboxylate groups of an μ₃-bridging dipicolinate. In the second unit, Cu2 is coordinated by two imidazole nitrogen atoms from 2-ethyl-1-H-benzimidazole (2) or 2-isopropyl-1-H-benzimidazole (3) ligands. Complex 2 is of higher symmetry and has a localized Cu(II) atom Cu2 in a special position on the twofold axis. EPR spectra of all three Cu(II) complexes, which were measured at both room temperature and 98 K, indicate distorted tetragonal coordination spheres for all the Cu(II) atoms. The g-factor relation (g_//>?g_┴?>?2.0023) is consistent with a \(d_{{x^{2} - y^{2} }}\) ground electronic state in each case.     

Synthesis and magnetic properties of copper(II)-cobalt(II) complexes ofN,N′-1,2-propanedisalicylamidatocuprate(II)

Summary The binuclear metal complexes [Cu(sampn)Co(L)₂] (L=bipy, phen), have been prepared by the reaction of sodiumN,N-1,2-propanedisalicylamidatocuprate(II) heptahydrate, Na₂[Cu(sampn)] 7H₂O, with a divalent metalion, and 2,2-bipyridine or 1, 10-phenathroline. The complexes were characterized by variable-temperature magnetic susceptibility measurements; the results indicate that a weak antiferromagnetic spin-exchange interaction operates between the metal ions.     

Features of сhitosan interaction with copper(II) and cobalt(II) tetrasulfophthalocyanines

The interaction of chitosan with copper(II) and cobalt(II) tetrasulfophthalocyanines is studied by spectral methods. The main parameters of binding of chitosan to anionic metal phthalocyanines are determined by Scatchard analysis. It is found that the formation of the polymer complex is considerably contributed by donor?acceptor interactions between the coordinately unsaturated metal phthalocyanine and chitosan amino groups. Сhitosan reacts with a monomeric cobalt(II) tetrasulfophthalocyanine, whereas copper(II) tetrasulfophthalocyanine in its complex with chitosan remains in the dimeric state. The reaction centers responsible for the Cu(SO₃H)₄Pc)₂–chitosan and Co(SO₃H)₄Pc–chitosan complexes are revealed by means of IR spectroscopy.