Binary and Ternary Complexes of Copper(II) Involving N,N,N′,N′-Tetramethylethylenediamine (Me4en) and Various Biologically Relevant Ligands

Binary and ternary complexes of copper(II) involving N,N,N′,N′-tetramethylethylene-diamine (Me₄en) and various biologically relevant ligands containing different functional groups are investigated. The ligands (L) used are dicarboxylic acids, amino acids, peptides and DNA unit constituents. The ternary complexes of amino acids, dicarboxylic acids or peptides are formed by simultaneous reactions. The results showed the formation of Cu(Me₄en)(L) complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was examined. Peptides form both Cu(Me₄en)(L) complexes and the corresponding deprotonated amide species Cu(Me₄en)(LH₋₁). The ternary complexes of copper(II) with (Me₄en) and DNA are formed in a stepwise process, whereby binding of copper(II) to (Me₄en) is followed by ligation of the DNA components. DNA constituents form both 1:1 and 1:2 complexes with Cu(Me₄en)²⁺. The concentration distribution of the complexes in solution was evaluated. [Cu(Me₄en)(CBDCA)] and [Cu(Me₄en)(malonate)] are isolated and characterized by elemental analysis and infrared measurements.     

Complex Formation Reactions of Promethazine Copper(II) and Various Biologically Relevant Ligands. Synthesis,Equilibrium Constants,Spectroscopic Characterization and Biological Activity

Binary and ternary complexes of copper(II) involving promethazine, N,N-dimethyl-3-(phenothiazin-10-yl)propylamine (Prom) and various biologically relevant ligands containing different functional groups, were investigated. The ligands (L) are dicarboxylic acids, amino acids, amides and DNA constituents. The ternary complexes of amino acids, dicarboxylic acids or amides are formed by simultaneous reactions. The results showed the formation of Cu(Prom)(L) complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was examined. Amides form both Cu(Prom)(L) complexes and the corresponding deprotonated species Cu(Prom)(LH₋₁). The ternary complexes of copper(II) with (Prom) and DNA are formed in a stepwise process, whereby binding of copper(II) to (Prom) is followed by ligation of the DNA components. DNA constituents form both 1:1 and 1:2 complexes with Cu(Prom)²⁺. The stability of these ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameters Δlog₁₀ K. The values of Δlog₁₀ K indicate that the ternary complexes containing aromatic amino acids were significantly more stable than the complexes containing alkyl- and hydroxyalkyl-substituted amino acids. The concentration distribution of various complex species formed in solution was also evaluated as a function of pH. The solid complexes [Cu(Prom)L)] where L=1,1-cyclobutanedicarboxylic acid (CBDCA), oxalic and malonic acid were isolated and characterized by elemental analysis, infrared, TGA, and magnetic susceptibility measurements. Spectroscopic studies of the complexes revealed that the complexes exhibits square planar coordination with copper(II). The isolated solid complexes have been screened for their antimicrobial activities using the disc diffusion method against some selected bacteria and fungi. The activity data show that the metal complexes are found to have antibacterial and antifungal activity.     

Synthesis, spectroscopic and electrochemical studies of a series of transition metal complexes with amino- or bis(bromomethyl)-substituted dppz-ligands: Building blocks for fullerene-based donor-bridge-acceptor dyads

Transition metal complexes with ligands based on dipyrido[3,2-a:2′,3′-c]phenazine (dppz) have been synthesized. As metal fragments the [Ru(bpy)₂]⁺, Re(CO)₃Cl and the [Cu(PPh₃)₂]⁺ moieties have been used. The complexes containing amino- or bis(bromomethyl) substituted dppz ligands can be used for fullerene-based donor-bridge-acceptor dyads. The electronic absorption spectra of these complexes and of the dppz ligands were investigated. The dppz ligands show strong absorptions in the 300 and 390 nm region. An additional absorption band in the visible region (∼440 nm) is observed for the amino-substituted dppz-ligands. Ruthenium complexes exhibited broad absorption bands at 350-500 nm arising from intraligand-based transitions and the MLCT transition. MLCT transitions of the Re(I) and Cu(I) complexes are observed as shoulders of the stronger ligand-based absorption band tailing out to 400-500 nm. The electrochemically active complexes and ligands were studied by cyclic voltammetry and square-wave voltammetry. All ligands show one first reversible one-electron reduction located at the phenazine portion. These reductions are shifted to more positive redox potentials upon complexation. Oxidation potentials for reversible processes could be determined for the Ru²⁺/Ru³⁺ couple. For rhenium(I) and copper(I) complexes one irreversible oxidation process is observed.     

Mixed Ligand Complex Formation Reactions and Equilibrium Studies of Cu(II) with Bidentate Heterocyclic Alcohol (N,O) and Some Bio-Relevant Ligands

The formation equilibria of copper(II) complexes and the ternary complexes Cu(HMI)L (HMI=4-Hydroxymethyl-imidazole, L=amino acid, amides or DNA constituents) have been investigated. Ternary complexes are formed by a simultaneous mechanism. The results showed the formation of Cu(HMI)L and Cu(HMI,H₋₁)(L) complexes. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in terms of the parameters Δlog ₁₀ K and log ₁₀ X. The effect of the side chains of amino acid ligands (Δ_R) on complex formation was discussed. The concentration distributions of various species formed in solution were also evaluated as a function of pH. The thermodynamic parameters ΔH° and ΔS° calculated from the temperature dependence of the equilibrium constants are investigated. The effects of dioxane as a solvent, on the protonation constant of HMI and the formation constants of Cu^II–HMI complexes, were discussed.     

Synthesis,structure and spectral studies on mixed ligand copper(II) complexes of diimines and acetylacetonate

Two new mixed ligand complexes of copper(II) with acetylacetonate (acac), 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) belonging to the class of cytotoxic and antineoplastic compounds known as CASIOPEINAS^® were synthesized and structurally characterized. Crystals of both complexes [Cu(acac)(bpy)(H₂O)]NO₃ · H₂O (1), [Cu(acac)(phen)Br] (2) contain square pyramidal Cu(II) complex species. In frozen solution both compounds give well resolved EPR spectra with very similar parameters.     

Complex Formation Reactions of (2,2′-dipyridylamine)copper(II) with Various Biologically Relevant Ligands. The Kinetics of Hydrolysis of Amino Acid Esters

Binary and ternary copper(II) complexes involving 2,2′-dipyridylamine (DPA) and various biologically relevant ligands containing different functional groups are investigated. The ligands used are dicarboxylic acids, amino acids, peptides and DNA unit constituents. The ternary complexes of amino acids, dicarboxylic acids or peptides are formed by simultaneous reactions. The results showed the formation of 1:1 complexes with amino acids and dicarboxylic acids. The effect of chelate ring size of the dicarboxylic acid complexes on their stability constants was examined. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. The ternary complexes of copper(II) with DPA and DNA are formed in a stepwise process, whereby binding of copper(II) to DPA is followed by ligation of the DNA components. DNA constituents form both 1:1 and 1:2 complexes with Cu(DPA)²⁺. The concentration distribution of the complexes in solution was evaluated. [Cu(DPA)(CBDCA)], [Cu(DPA)(malonate)] and [Cu(DPA)(oxalate)] were isolated and characterized by elemental analysis, i.r. and magnetic measurements. Spectroscopic studies of [Cu(DPA)(malonate)] revealed that the complex exhibits square planner coordination with copper(II). The hydrolysis of glycine methyl ester (MeGly) is catalyzed by the Cu(DPA)²⁺ complex. The reaction has been studied by a pH-state technique over the pH range 5.8–6.8 at 25 °C and I=0.1 mol dm⁻¹. The kinetic data fits assuming that the hydrolysis proceeds in two steps. The first step, involving coordination of the amino acid ester by the amino and carboxylic group, is followed by the rate-determining attack by the OH⁻ ion. The second step involves equilibrium formation of the hydroxo-complex, Cu(DPA)(MeGly)(OH), followed by intramolecular attack.     

Assembling of copper(II) dipicolinate complexes

The role of ancillary ligands, namely imidazole (im), pyridine (py), 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) in the assembly of copper(II) dipicolinate complexes are presented. Mononuclear complexes are observed in the case of monodentate ligands. The mononuclear complex [Cu(im)₃L]·4H₂O (1) (L = dipicolinate anion) has a distorted octahedral structure with Z′ = 2, whereas [CuL(py)(H₂O)]·2H₂O (2) adopts distorted square pyramidal geometry. The bidentate ligands bpy and phen favor the formation of dinuclear complexes. The dinuclear complex [CuL(bpy)(μ-L)Cu(bpy)(H₂O)]·9H₂O (3) has one carbonyl oxygen atom of a carboxylate group of dipicolinate acting as a bridging ligand to the copper site that is devoid of a coordinated water molecule. The complex has an angle of 83.55° between the plane of L and bpy attached to one copper site, whereas it has an angle of 78.13° between the plane L and bpy attached to the other copper site. A 1,10-phenanthroline containing dinuclear copper(II) dipicolinate complex, [Cu(phen)(H₂O)(μ-L)Cu(phen)₂][CuL₂]·12H₂O (4), has been structurally characterized. It has an unusual carboxylate bridge.     

Supramolecular structures of macromolecules containing bipyridine–copper(I) complexes as revealed from transmission electron microscopy studies

Transmission electron microscopy (TEM) studies on bipyridine (bpy) containing block copolymer systems showed the formation of nanoscopic polymer–ion complexes through complexation with copper(I) ions which segregated to highly ordered columnar domains of mesoscopic dimensions. The domains, i.e. stacks of [(bpy)₂Cu(I)] complex moieties could be visualized by complementary TEM techniques. First, electron energy loss spectra (EELS) showed the absorption edges of copper and nitrogen, which are specific for the bipyridine copper complexes. The element spectroscopic imaging (ESI) technique allowed the imaging of the net copper and net nitrogen distribution, and the coinciding pictures exhibited a microphase separated system in the case of a 3-block copolymer with complexed end segments. High resolution elastic bright field images showed interference lines with a line to line distance of about 8 A which could be related to the Cu–Cu distance in staggered Cu(I)–bipyridine complexes. Received: 6 August 1997 Accepted: 28 April 1998     

The state of metals in the Pt/Al2O3 and (Pt-Cu)/Al2O3 catalysts as indicated by IR spectroscopy with isotope dilution of 12C16O with 13C18O molecules

Adsorption of ¹³C¹⁸O+¹²C¹⁶O mixtures on the Pt(2.9%)/γ-Al₂O₃, (Pt(2.6%)+Cu(2.7%))/γ-Al₂O₃, and (Pt(2.6%)+Cu(5.1%))/γ-Al₂O₃ catalysts was studied by FTIR spectroscopy. On the metallic Pt surface at coverages close to saturation, CO is adsorbed both strongly and weakly to form linear species for which the vibrational frequencies of the isolated ¹³C¹⁸O molecules adsorbed on Pt are ∼1940 and ∼1970 cm⁻¹, respectively. The redistribution of intensities of the high-and low-frequency absorption bands in the spectra of adsorbed ¹³C¹⁸O indicates that these linear forms are present on the adjacent metal sites. The weak adsorption is responsible for the fast isotope exchange between the gaseous CO and CO molecules adsorbed on metal. The Pt-Cu alloys, in which the electronic state of the surface Pt atoms characteristic of monometallic Pt remains unchanged, are formed on the surface of the reduced Pt-Cu bimetallic catalysts. The decrease in the vibrational frequencies of the isolated C=O bonds in the isolated Pt-CO complexes suggests that the CO molecules adsorbed on the Cu atoms affect the electronic properties of Pt. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 831–836, May, 2007.     

Mixed complex formation of copper(II) with 2,2′, 2″-terpyridine and some tridentate ligands in aqueous solution

Summary The formation of copper(II) ternary complexes [Cu(tpy)(L)] (tpy = 2,2,2-terpyridine; L = oxydiacetate, thiodiacetate, iminodiacetate or dipicolinate) has been studied by potentiometric measurements in aqueous solution at 25° and I = 0.1 mol dm^–3 (NaNO₃ or NaClO₄). All the systems investigated also form protonated species of the [Cu(tpy)(L)H]⁺ type. The effect of the different heteroatoms (donor atoms) in the ligands L (i.e. O, S or N), other than oxygens of the carboxylic groups, on the stability of the mixed complexes has been evaluated and compared with the trends observed for the analogous complexes of copper(II) with 2,2-bipyridine (bpy).The stabilization of ternary complexes of copper(II) with respect to the different coordination levels is also discussed.     

Stabilities of the Ternary Complexes of Copper(II) with Substituted 1,10-Phenanthrolines and Some Amino Acids in Aqueous Solution

In this study the binary and ternary complexes of copper(II) with substituted 1,10-phenanthrolines [s-phen: 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (dmphen) and 5-nitro-1,10-phenanthroline (nphen)] and l-amino acids [aa: l-phenylalanine (phe), l-tyrosine (tyr) and l-tryptophan (trp)] have been investigated using potentiometric methods in 0.1 mol·L^?1 KCl aqueous ionic media at 298.2 K. The protonation constants of the ligands and the stability constants of the binary and ternary complexes of Cu(II) with the ligands were calculated from the potentiometric data using the “BEST” software package. It was inferred that the aromatic 1,10-phenanthrolines act as a primary ligand in the ternary complexes, while the oxygen and nitrogen donor-containing amino acids are secondary ligands. The observed values of Δlog₁₀ K indicate that the ternary complexes are more stable than the binary ones, suggesting no interaction takes place between the ligands in the ternary complexes. The magnitudes of the measured stability constants of all of the ternary complexes are in the order [Cu(s-phen)(trp)]⁺ > [Cu(s-phen)(tyr)]⁺ > [Cu(s-phen)(phe)]⁺, which is identical to the sequence found for the binary complexes of Cu(II) with the amino acids. When the substituted 1,10-phenanthroline is changed, the stability constants of the ternary complexes decrease in the following order: [Cu(dmphen)(aa)]⁺ > [Cu(phen)(aa)]⁺ > [Cu(nphen)(aa)]⁺.     

Theoretical study of vibration spectra of sensitizing dyes for photoelectrical converters based on ruthenium(II) and iridium(III) complexes

Quantum-chemical method of the density functional theory was employed to calculate, with the use of a B3LYP hybrid exchange-correlation functional, the IR absorption and Raman spectra of [Ru(bpy)₂(CN)₂] and [Ir(bpy)₂(CN)₂]⁺ complexes. All the normal vibrational frequencies were analyzed and new assignments of a number of bands in the IR absorption and Raman spectra were made. The role of vibrational motions of metal atoms and ligands in the vibronic deformation of electron shells in the course of electron transfer was discussed. This was done using data on surface-enhanced Raman spectra of [Fe(bpy)₂(CN)₂] and [Ru(bpy)₃]²⁺ complexes adsorbed on the surface of colloid silver.     

Coordination chemistry of copper(II) complexes with N4, N4S2, and N4O2 donor macrocyclic ligands: Biological aspects—antifungal, synthesis, spectral studies, and magnetic moments

Three macrocyclic ligands and their complexes with copper(II) salts (with anions Cl⁻, NO ₃ ⁻ , and NCS⁻) were prepared and investigated using a combination of microanalytical analysis, melting point, molar conductance measurement, magnetic susceptibility measurement, and electronic, IR and ESR spectral studies. Ligands L¹, L², and L³ having N₄, N₄O₂, and N₄S₂ core, respectively, and all the donor atoms of these ligands are bonded with Cu, which is confirmed by a seven-line pattern observed at half-field in the frozen (H₂O: MeOH = 10: 1 at pH 10) solution ESR spectrum. The polycrystalline ESR data (g _∥ = 2.20–2.27, g _⊥ = 2.01–2.05, and A _∥ = 120–270) of all the complexes together with the high asymmetry geometry suggest that all complexes appear to be near the static distortion (CuN₄O₂ and CuN₄S₂ chromophore geometry). The electronic spectra of the complexes involve two bands at the same intensity corresponding to a cis-distorted octahedral geometry. A common structural feature of both ligand L² and ligand L³ is that two different donor atoms at five-membered heterocyclic aromatic ring due to this N₄O₂ and N₄S₂ chromophore form stable six-membered chelate rings with metals via these two, Cu-O and Cu-S, new interactions comparatively to the first macrocyclic ligand, which has four-membered N,N′-chelate rings. The cyclic voltammetric studies point to a two-step electron transfer indicating the reduction of the two copper atoms to copper(I), i.e., Cu(III)Cu(II) ⇄ Cu(II)Cu(I) ⇄ Cu(I)Cu(0). The molar conductance for the complexes corresponds to 1: 2 and is nonelectrolyte in nature. The magnetic moment (μ_eff) of the complexes lie in the range between 1.80–1.96 μ_B. Finally, these complexes were screened for their antimicrobial activity against Aspergillus-niger of fungal strains. The text was submitted by the authors in English.     

Fac-mer equilibria of coordinated iminodiacetate (IDA2?) in ternary CuII(ida)(H?1B)? complex formation (B = imidazole, benzimidazole) in aqueous solution

pH potentiometric and spectrophotometric investigations on the complex formation equilibria of Cu^II with iminodiacetate (ida²⁻) and heterocyclic N-bases, viz. imidazole and benzimidazole (B), in aqueous solution in binary and ternary systems using different molar ratios of the reactants indicated the formation of complexes of the types, Cu(ida), Cu(ida)(OH)⁻, (ida)Cu(OH)Cu(ida)⁻, Cu(B)²⁺, Cu(H^-1B)⁺, Cu(ida)(H₋₁B)⁻, (ida)Cu(B)Cu(ida) and (ida)Cu(H₋₁B)Cu(ida)⁻. Formation constants of the complexes at 25 ±1° at a fixed ionic strength,I = 0.1 mol dm⁻³ (NaNO₃) in aqueous solution were evaluated and the complex formation equilibria were elucidated with the aid of speciation curves. Departure of the experimental values of the reproportionation constants(ΔlogK _cu) of ternary Cu(ida)(H₋₁B)⁻ complexes from the statistically expected values, despite their formation in appreciable amounts at equilibrium, were assigned tofac(f)-mer(m) equilibria of the ida²⁻ ligand coordinated to Cu^II, as the N-heterocyclic donors, (H₋₁B)⁻, coordinatetrans- to the N-(ida²⁻) atom in the binary Cu(ida) _f complex to form the ternary Cu(ida) _m (H₋₁B)⁻ complexes     

Synthesis and characterization of the [Cu(Cin2bda)2]ClO4 and [Cu(Ncin2bda)2]ClO4 complexes: Crystal structure of [Cu(Ncin2bda)2]ClO4

Two copper(I) complexes [Cu(Cin₂bda)₂]ClO₄ (I) and [Cu(Ncin₂bda)₂]ClO₄ (II) have been prepared by the reaction of the ligands N²,N²′-bis(3-phenylallylidene)biphenyl-2,2′-diamine (L¹) and N²,N²′-bis[3-(2-nitrophenyl)allylidene]biphenyl-2,2′-diamine (L²) and copper(I) salt. These compounds were characterized by CHN analyses, ¹H NMR, IR, and UV-Vis spectroscopy. The C=N stretching frequency in the copper(I) complexes shows a shift to a lower frequency relative to the free ligand due to the coordination of the nitrogen atoms. The crystal and molecular structure of II was determined by X-ray single-crystal crystallography. The coordination polyhedron about the copper(I) center in the complex is best described as a distorted tetrahedron. A quasireversible redox behavior was observed for complexes I and II. The article is published in the original.     

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.     

Transition metals as electron traps. I. Structures,energetics, electron capture,and electron‐transfer‐induced dissociations of ternary copper–peptide complexes in the gas phase

Electron‐induced dissociations of gas‐phase ternary copper‐2,2′‐bipyridine complexes of Gly‐Gly‐Gly and Gly‐Gly‐Leu were studied on a time scale ranging from 130 ns to several milliseconds using a combination of charge‐reversal (⁺CR^?) and electron‐capture‐induced dissociation (ECID) measured on a beam instrument and electron capture dissociation (ECD) measured in a Penning trap. Charge‐reduced intermediates were observed on the short time scale in the ⁺CR^? and ECID experiments but not in ECD. Ion dissociations following electron transfer or capture mostly occurred by competitive bpy or peptide ligand loss, whereas peptide backbone fragmentations were suppressed in the presence of the ligated metal ion. Extensive electron structure theory calculations using density functional theory and large basis sets provided optimized structures and energies for the precursor ions, charge‐reduced intermediates, and dissociation products. The Cu complexes underwent substantial structure changes upon electron capture. Cu was calculated to be pentacoordinated in the most stable singly charged complexes of the [Cu(peptide ? H)bpy]^{+ ?} type where it carried a ～+ 1 atomic charge. Cu coordination in charge‐reduced [Cu(peptide ? H)bpy] intermediates depended on the spin state. The themodynamically more stable singlet states had tricoordinated Cu, whereas triplet states had a tetracoordinated Cu. Cu was tricoordinated in stable [Cu(peptide ? H)bpy]^{? ?} products of electron transfer. [Cu(peptide)bpy]^{2 + ?} complexes contained the peptide ligand in a zwitterionic form while Cu was tetracoordinated. Upon electron capture, Cu was tri‐ or tetracoordinated in the [Cu(peptide)bpy]⁺ charge‐reduced analogs and the peptide ligands underwent prototropic isomerization to canonical forms. The role of excited singlet and triplet electronic states is assessed. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and Single-crystal Structures of Two Copper(II) Complexes and One Iron(II) Complex Prepared by in situ Ligand Substitution at Room Temperature

Two hexa-coordinate copper(II) complexes formulated as [Cu(phen)(4-dmampy)₂(ClO₄)₂] and [Cu(bpy)(3-ampy)₂(ClO₄)₂] · 0.5CH₃OH · 0.5H₂O (phen = 1,10–phenanthroline bpy = 2,2′-bipyridine, 3-ampy = 3-aminopyridine, 4-dmampy = 4-dimethylaminopyridine), and one low-spin ferrous complex formulated as [Fe(dmbpy)₃](ClO₄)₂ · H₂O (dmbpy = 4,4′-dimethyl-2,2′-bipyridine), were synthesized by in situ ligand substitution at room temperature, and characterized by X-ray single-crystal diffraction. This is the first structural report where either 4-dmampy and phen molecules, or 3-ampy and bpy molecules, are located simultaneously around one metal center.     

Low-dimensional Compounds Containing Cyano Groups. XI. Preparation,Crystal Structure and Properties of Two Copper(II) Dicyanamide Complexes with PF<Stack><Subscript>6</Subscript><Superscript>−</Superscript></Stack> Anions

From the reaction mixtures containing Cu(NO₃)₂, Na[N(CN)₂], KPF₆ and 2,2′-bipyridine (bpy) or 1,10- phenanthroline (phen) in 1:1:1:2 molar ratios, [Cu(bpy)₂N(CN)₂][Cu(bpy)₂(H₂O)](PF₆)₃ (1b) and [Cu (phen)₂N(CN)₂]PF₆ (1p) complexes were isolated. Measured i.r. spectra confirm the presence of all functional groups in both complexes and, moreover, they indicate monodentate coordination of dicyanamide through the cyano nitrogen atom in (1p). The structure of (1b) contains two crystallographically independent complex cations. In both, Cu is coordinated by two chelating bpy molecules, and either dicyanamide anion or water molecule fills the fifth position, completing the basal plane. The Cu^II atoms in (1p) are coordinated by two chelating phen ligands and by one dicyanamide anion in the equatorial plane. Hexafluorophosphate anions in (1b) and (1p) remain uncoordinated. Besides the ionic forces in both structures, the structure of (1b) is stabilized by strong O—H···F and O—H···N hydrogen bonds and, moreover, both structures are stabilized by weak C—H···F hydrogen bonds and possible π-π interactions between pyridine rings of bpy or phen molecules.     

Crystal structure and strong antiferromagnetic interaction of a terephthalate-bridged binuclear copper(II) Complex, [{Cu(dipn)}2(μ-TPHA)](ClO4)2 (dipn = N-(3-aminopropyl)-1,3-propanediamine)

Three binuclear copper(II) complexes bridged by three different bridging ligands: μ-TPHA (terephthalato), μ-PHTA (phthalato) and μ-TCB (tetracarboxylatobenzene) have been synthesized. The crystal structure of [{Cu(dipn)}₂(μ-TPHA)](ClO₄)₂ where dipn = N-(3-aminopropyl)-1,3-propanediamine was solved at room temperature. The [{Cudipn}₂(μ-TPHA)](ClO₄)₂ complex consists of a μ-terephthalato bridging binuclear copper(II) cationic unit and two non-coordinated perchlorate anions. The TPHA ligand bridges in a bismonodentate fashion. The environment of the copper(II) ion is a distorted plane-square-planar coordination sphere. The magnetic properties of the three complexes have been investigated in the 75–300 K range, and show that the geometry of the Cu^II atom is the important factor for magnetic interactions in the terephthalato bridging binuclear copper(II) complexes. This revised version was published online in June 2006 with corrections to the Cover Date.