Synthesis and solvatochromism studies of new mixed-chelate dinuclear copper(II) complexes with different counter ions

Four new symmetric mixed-chelate dinuclear complexes type [Cu₂(L)₂(TAE)]X₂, where TAE = tetraacetylethane; L = N,N-dimethyl-N′-benzylethylenediamine (L¹) or N,N′-dibenylethylenediamine (L²); X = ClO₄ or BPh₄ have been synthesized and characterized on the bases of elemental analysis, spectroscopic and conductance measurements. The X-ray crystal analysis of [Cu₂(L¹)₂(TAE)](ClO₄)₂ demonstrated that the two copper(II) ions are not equivalent. The axial position of the first copper is occupied by a ClO₄⁻ ion with a square pyramidal geometry whereas; the second copper ion resides in an octahedral environment determined by two perchlorate anions. However, in solution, the perchlorate ions are driven out by solvent molecules leading to their solvatochromism. The solvatochromism of the complexes were investigated in various organic solvents and also were compared with those of the corresponding mononuclear complexes [Cu(L)(acac)]ClO₄. Their solvatochromism were also investigated with different solvent parameters models using stepwise multiple linear regression (SMLR) method. The results suggested that the DN parameter of the solvent has the dominate contribution to the shift of the d-d absorption band of the complexes. The results demonstrated that the complexes with counter ions of BPh₄ are more solvatochromic in very weak donor solvents owing to their disinclination in ion-pair formation.     

Synthesis, crystal structure, spectroscopic and magnetic properties of copper(II) complexes with 2-(2-pyridyl)imino-N-(2-thiazolin-2-yl)thiazolidine (PyTT)

The copper(II) complexes [Cu(PyTT)₂(H₂O)](NO₃)₂ (A) and [CuCl₂(μ-PyTT)₂CuCl(H₂O)]Cl · 3H₂O (B) were synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, UV-Vis-NIR diffuse reflectance and magnetic susceptibility measurements. In the mononuclear compound A the copper ion is in a distorted square pyramidal geometry, with the equatorial plane formed by two thiazoline nitrogen atoms, one imino nitrogen atom and one water molecule, whereas the axial site is occupied by one imino nitrogen atom. The compound B is dinuclear and both Cu(II) centres present environments that can be described as slightly distorted square pyramidal geometries. The observed molar magnetic susceptibility for A (μ=2.13 BM) allows to exclude metal-metal interactions, supporting a monomeric structural formulation for this compound. In compound B, magnetic susceptibility measurements in the temperature range 6.2-288 K show an intradimer antiferromagnetic interaction (J=−11.8 cm⁻¹).     

A new blue luminescent dichlorido-bridged dinuclear copper(II) complex with DNA binding and cytotoxic activities: Synthesis, structure and DFT studies

A blue luminescent dichlorido-bridged dinuclear copper(II) (S = 1/2) complex, [Cu^II₂(HL)₂(μ-Cl)₂]·2H₂O, 1a was synthesized with the 1:1 reaction of the acyclic tridentate salicylaldehyde 2-pyridyl hydrazone ligand, HL, 1. The complex 1a displays multiple bands in the visible region (400-470 nm). The association constant (K_ass, UV-Vis) was found to be 1.186 × 10⁴ for 1a at 298 K. The copper(II)-copper(III) oxidation potential lies near 0.32 V versus Ag/AgCl electrode. On excitation at 390 nm, the ligand 1 strongly emits at 444 nm due to an intraligand ¹(π-π^∗) transition. Upon complexation with copper(II) the emission peak is slightly red shifted (λ_ex 390 nm, λ_em 450 nm, F/F₀ 0.81) with little quenching. Molecular structure of 1a (Cu···Cu 3.523 Å) has been determined by single crystal X-ray diffraction studies. DFT and TDDFT calculations strongly support the spectral behavior of the ligand and the complex. The complex 1a exhibits a strong interaction towards DNA as revealed from the K_b (intrinsic binding constant) 2.05 × 10⁴ M⁻¹ and K_sv (Stern-Volmer quenching constant) 2.47 values. The complex exhibits cytotoxic effect and the LD₅₀ value for HeLa cells was calculated as 5.44 μM at which the cell cycle was arrested at G₂/M phase.     

Synthesis, crystal structures and magnetic studies of terephthalato- and fumarato-bridged dinickel(II) complexes with tripodal poly-benzimidazole ligand

Two novel dinuclear nickel(II) complexes [Ni₂(ntb)₂(μ-tp)(H₂O)_1.61(CH₃OH)_0.39](NO₃)₂·5.13CH₃OH·2.25H₂O (1) and [Ni₂(ntb)₂(μ-fum)(H₂O)(CH₃OH)](NO₃)₂·6CH₃OH·H₂O (2) (tp = terephthalate dianion, fum = fumarate dianion, ntb = tris(2-benzimidazolylmethyl)amine) containing tetradentate poly-benzimidazole ligand were synthesized and structurally characterized by IR spectra, UV-Vis, elemental analysis and X-ray crystallography. The Ni(II) ions in 1 and 2 have distorted octahedral geometry with four nitrogen atoms of ntb, one oxygen atom of water and one oxygen atom supplied by the carboxylate group of the bridged dicarboxylato ligand. Complexes 1 and 2 consist of terephthalato- and fumarato-bridged dinickel(II) centers in bis(monodentate) bonding fashion. The Ni?Ni distances are 11.333 Å for 1 and 8.966 Å for 2. The magnetic susceptibility measurements at variable temperature show that two complexes exhibit weak antiferromagnetic interactions between nickel(II) ions with J values of −0.25 cm⁻¹ and −0.36 cm⁻¹, respectively.     

Kinetics and DFT studies on the reaction of copper(II) complexes and H2O2

Copper(II) complexes supported by bulky tridentate ligands L1^H (N,N-bis(2-quinolylmethyl)-2-phenylethylamine) and L1^Ph (N,N-bis(2-quinolylmethyl)-2,2-diphenylethylamine) have been prepared and their crystal structures as well as some physicochemical properties have been explored. Each complex exhibits a square pyramidal structure containing a coordinated solvent molecule at an equatorial position and a weakly coordinated counter anion (or water) at an axial position. The copper(II) complexes reacted readily with H₂O₂ at a low temperature to give mononuclear hydroperoxo copper(II) complexes. Kinetics and DFT studies have suggested that, in the initial stage of the reaction, deprotonated hydrogen peroxide attacks the cupric ion, presumably at the axial position, to give a hydroperoxo copper(II) complex retaining the coordinated solvent molecule (H ^R ·S). H ^R ·S then loses the solvent to give a tetragonal copper(II)-hydroperoxo complex (H ^R ), in which the –OOH group may occupy an equatorial position. The copper(II)–hydroperoxo complex H ^R exhibits a relatively high O–O bond stretching vibration at 900 cm⁻¹ compared to other previously reported examples.Electronic Supplementary Material Supplementary material is available for this article at     

Spectral and structural studies of a new oxalato-bridged dinuclear copper(II) complex having two 3-(thiophen-2-yl)-1,10-phenanthroline ligands in a trans configuration

In this paper, spectral and structural characterizations of a new dinuclear copper(II) complex (1), formulated as [Cu₂(3-(thiophen-2-yl)-1,10-phenanthroline)₂(μ-oxalate)(DMF)₂](ClO₄)₂ (DMF = N,N′-dimethylformamide), have been described. Two five-coordinate copper(II) centers are bridged by a four-dentate oxalate dianion forming a planar molecular geometry with the Cu-Cu separation of 5.117(4) Å. The two ligands in 1 adopt a trans configuration to each other and two monodentate DMF molecules are positioned at each side of the molecular plane. In addition, typical π-π stacking interactions are found between adjacent phenanthroline and thiophene rings forming a layered packing structure. A compressed pyramidal configurational alteration is observed for each copper(II) center when the temperature is decreased from 291(2) to 100(2) K.     

DNA-binding and cleavage studies of novel binuclear copper(II) complex with 1,1'-dimethyl-2,2'-biimidazole ligand

DNA-binding properties of novel binulear copper(II) complex [Cu(2)(Dmbiim)(4)(H(2)O)(2)](ClO(4))(4).6H(2)O, where Dmbiim = 1,1'-Dimethyl-2,2'-biimidazole are investigated using electronic absorption spectroscopy, fluorescence spectroscopy, viscosity measurement and voltammetry. The results show that the copper(II) complex interacts with DNA through minor groove binding. The interaction between the complex and DNA has also been investigated by gel electrophoresis, interestingly, we found that the copper(II) complex can cleave circular plasmid pBR322 DNA efficiently in the presence of AH(2) (ascorbic acid) at pH 8.0 and 37 degrees C.     

Studies of copper(II) and nickel(II) complexation by bis(1,4,7-triazacyclononane) ligands containing alkene and alkyne bridging groups

The copper(II) and nickel(II) complexes of three new 1,2-bis(1,4,7-triazacyclononane) ligands containing unsaturated four carbon bridging groups is studied by continuous variation UV-Vis spectroscopic and pH potentiometric equilibrium experiments. The cis-butene-2 (L_C) linked ligand may form monomeric MN₆-type complexes while the trans-butene-2 (L_T) and butyne-2 (L_Y) ligands are prevented by their stereochemistry from forming monomeric complexes and form oligomeric complexes. It is determined that the stability of the CuL_C²⁺ complex is not appreciably different from the oligomeric complexes of L_T and L_Y. Single-crystal X-ray structure determinations are made on three square pyramidal Cu₂L⁴⁺ complexes: [Cu₂L_CCl₄] (1), [Cu₂L_YCl₄] (2), and [Cu₂L_T(NO₃)₂(H₂O)₂](NO₃)₂ (3). The structure of [Ni₂(L_C)₂](ClO₄)₄ · 2H₂O (4) is a binuclear dimer that contains two nickel(II) ions sandwiched between two ligands, indicating that bis([9]aneN₃) ligands with four linker atom chains may form either monomeric or oligomeric structures.     

Acid-base and copper (II) complexation equilibria of poly(inosinic)-poly(cytidylic)

The acid-base and copper (II) complexing properties of the heteropolynucleotide poly(inosinic)-poly(cytidylic) acid were studied by means of potentiometric, spectrophotometric, CD, and molecular fluorescence titrations in a working aqueous medium of 0.15 M ionic strength at 37°C. The study of the acid-base equilibria has proved the existence of four different species in the pH interval 2–11. Two new species are detected in the presence of copper(II) ion, at acidic and neutral pH values. Spectrophotometric, CD, melting, and fluorescence data were treated with a multivariate curve resolution procedure that allowed the determination of the number of species simultaneously present in each system [acid-base equilibria, copper(II) complexation equilibria], and the estimation of their concentration profiles and of the pure spectra for each species. From the concentration profiles an unambiguous assignment of which species are present at any pH conditions can be made. Furthermore, the knowledge of the pure uv-visible, fluorescence, and CD spectra recovered by the proposed resolution method for each species brings important structural information. When this mathematical approach was applied to the thermal denaturation data, the melting profile and the uv pure spectra for all the different species or conformations formed in the melting process, were calculated. © 1997 John Wiley & Sons, Inc. Biopoly 42: 271–283, 1997     

Electrochemical synthesis and crystal structure of iron(II), cobalt(II), nickel(II) and copper(II) complexes of dianionic tetradentate N4 Schiff base ligand

The electrochemical oxidation of anodic metal (iron, cobalt, nickel and copper) in an acetonitrile solution of the potentially chelating Schiff base N,N(dithiodiethylenebis-(aminylydenemethylydene)-bis(1,2-phenylene)ditosylamide (H₂L) afforded stable complexes of empirical formula [ML]. The compounds obtained have been characterized by microanalysis, IR spectroscopy and ES-MS mass spectrometry. The crystal and molecular structures of [FeL]·CH₃CN (1) [CoL]·CH₃CN (2), [NiL]·CH₃CN (3) and [CuL]·CH₃CN (4) have been determined by X-ray diffraction in all complexes, the metal atom is in a distorted tetrahedral environment with the Schiff base acting as a tetradentate N4 donor.     

Coordination properties of ethyl bis(pyridin-2-ylmethyl)phosphate ligand with copper and zinc chloride. X-ray crystal structure of Cu(II) complex

A new ethyl bis(pyridin-2-ylmethyl)phosphate (2-bis(pm)Ope) ligand has been synthesized and used for synthesis of copper(II) and zinc(II) complexes of the formula [MCl₂(2-bis(pm)Ope)] [M = Cu(II), Zn(II)]. Despite having the same general formula, Cu(II) and Zn(II) complexes are not isostructural. The Zn(II) complex is four coordinated (MCl₂N₂) forming probably tetrahedral structure whereas the Cu(II) complex of distorted square pyramidal geometry is five coordinated (MCl₂ON₂). The later compound not only coordinates by two nitrogen atoms of pyridine rings but also by the oxygen atom of pyridin-2-ylmethoxyl residue. The compound (2-bis(pm)Ope) has been obtained as the product of diethyl (pyridin-2-ylmethyl)phosphate’s (2-pmOpe) transestrification. The compounds have been identified and characterized by IR, far-IR, ¹H NMR, ³¹P NMR and elemental analyses. The crystal structure of copper(II) complex i.e. [CuCl₂(2-bis(pm)Ope)] has been determined by the X-ray diffraction method. The low temperature magnetic study reveals significant antiferromagnetic interaction between copper centers through the H-bond system.     

A double helical dicopper(II) complex with biacetyl bis(benzoylhydrazone)

A dinuclear double helicate of copper(II) with the Schiff base biacetyl bis(benzoylhydrazone) (H₂babh) is reported. The solid state physical properties of the dicopper(II) species are compared with that of its mononuclear precursor. The O,N,N,O-donor babh²⁻ shows an unusual bridging coordination mode in [Cu₂(μ-babh)₂]. Each metal center in the complex is in very similar tetrahedrally distorted square-planar N₂O₂ coordination sphere assembled by the two halves of the two babh²⁻. To accommodate the metal centers, two halves of each ligand are twisted along the (CH₃)C-C(CH₃) bond.     

Unprecedented formation of binuclear copper(II) complex with a perylene derived ligand by the oxidative reaction

A new perylene-pendent tridentate ligand, N-(3-perylenylmethyl)-N,N-bis(2-pyridylmethyl)amine (perbpa) 1 and its Cu(II) complex, [Cu(perbpa)Cl₂] (2) were prepared and structurally characterized by the X-ray diffraction method. In the packing structure of ligand 1, perylene groups were aggregated to form a π-π stacked layer of dimerized pelylene moieties similar to the packing of pristine perylene. This result suggests both that the π-π interactions among the perylene moieties predominate for the arrangement of perbpa molecules in the crystal and that this ligand is a good candidate for constructing electron conducting path. A complex 2 was prepared from the ligand 1 and a copper(II) chloride dehydrate. Complex 2 had a mononuclear and 5-coordinate distorted square pyramidal structure with a perbpa and two coordinated chloride ions. The chemical oxidation of 2 by iodine resulted in the unprecedented binuclear Cu(II) species, [Cu₂(μ-Cl)₂(perbpa)₂](I₃)₂, 3·(I₃)₂. An X-ray crystal structure analysis of 3·(I₃)₂ revealed the binuclear structure bridged by the chloride ions. A temperature dependent magnetic susceptibility measurement of 3 showed a weak ferromagnetic exchange interaction with S = 1 ground state, g = 2.12 and J = +1.17 cm⁻¹, based on H = −2JS₁ · S₂. The UV-Vis absorption and the EPR spectra of 3 showed that the perylene groups are not oxidized. These results indicate a couple of Cu(II) constructed S = 1 ground state with intermolecular ferromagnetic interaction. The electrochemical study suggested that the crystallization of 3·(I₃)₂ was initiated by the oxidation of the N,N-bis-(2-pyridylmethyl)amino (bpa) groups of 2 by I₂.     

Iron release from transferrin induced by mixed ligand complexes of copper(II)

Summary Copper(II) complexes CuL₁L₂ with the ligand pairs 3-phosphoglycerate (PG)/ethylenediamine (en), phosphoserine (PS)/ethylenediamine, phosphoserine/malonate (mal) are shown to be effective in inducing the release of both iron atoms from di-ferric transferrin (Fe2Tf; human serum transferrin) at pH 7.3 in 1 M NaCl at 25°C. Half-times of the reaction with Cu(PG)(en)^– were less than 1 min at 0.02 M concentration. The iron(III) products are polynuclear hydroxo complexes. There is weaker interaction with Cu(PS) ₂ ^4– and virtually none with Cu(serine)(en) nor Cu(PS)(2,2-bipyridyl)^–, revealing crucial effects of the combined ligand sphere including the phosphomonoester group. The results suggest that the release of iron from Fe2Tf, or from either monoferric transferrins, occurred due to the breakdown of the stability of iron binding in conjunction with the expulsion of the synergistic anion carbonate (or oxalate). The active copper(II) complexes are postulated to be models of membrane components that could liberate iron from transferrin succeeding its uptake at the receptor sites of cells.Abbreviations PG phosphoglycerate - PS phosphoserine - en ethylenediamine - Fe2Tf diferric transferrin - Fe_cTf and Fe_NTf transferrin with iron bound to the lobe containing the C- or N-terminus, respectively - apoTf apotransferrin - K-3 all-cis-1,3,5-tris(trimethylammonio)-2,4,6-cyclo-hexanetriol - NTA nitrilotriacetic acid; bipy, 2,2-bipyridine; mal, malonate     

Copper(II) complexes of carnosine, glycylglycine, and glycylglycine-imidazole mixtures

Carnosine complexes with copper(II) ions were studied with magnetic resonance techniques over a wide range of ligand to metal ratios at various pH values. Water proton relaxation rates increased with decreasing carnosine to copper ratios until a molar ratio of 48 was reached. Over the ratio range of 48–2 carnosine molecules per copper ion, the relaxation rate decreased so that in the 2:1 carnosine-copper(II) complex, the water-copper(II) distance was estimated to be 1.92 Å. Proton NMR studies revealed the broadening of imidazole proton lines at high mole ratios followed by other histidyl protons as the ratio decreased. The β-alanyl methylene protons were the last to be broadened by the addition of copper(II) ions. Carbon to copper(II) distances were determined for the carnosine to copper mole ratios of 500:1 and 5000:1. EPR spectra obtained at 93°K revealed the probable existence of four carnosine imidazoles as the sole coordinated ligands to copper(II) at high dipeptide-to-metal ratios (>10). At mole ratios below four, nuclear hyperfine lines characteristic of both monomeric and dimeric carnosine-copper(II) forms were observed. These results reveal that imidazole from carnosine is the sole ligand contributed to copper(II) for coordination over the pH range 5 to 7 at high carnosine to copper(II) ratios     

Squarato-metal(II) complexes. 1: Structural and magnetic characterization of squarato-bridged dinuclear nickel(II) and copper(II) complexes

A new series of dinuclear squarato-bridged nickel(II) and copper(II) complexes [Ni₂(2,3,2-tet)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂ (1), [Ni₂(aepn)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂ (2), [Cu₂(pmedien)₂(μ_1,3-C₄O₄)(H₂O)₂](ClO₄)₂.4H₂O (3) and [Cu₂(DPA)₂(μ_1,2-C₄O₄)(H₂O)₂](ClO₄)₂ (4) where is the dianion of 3,4-dihydroxycyclobut-3-en-1,2-dione (squaric acid), 2,3,2-tet = 1,4,8,11-tetraazaundecane, aepn = N-(2-aminoethyl)-1,3-propanediamine, pmedien = N,N,N′,N″,N″-pentamethyldiethylenetriamine and DPA = di(2-pyridylmethyl)amine were synthesized and structurally characterized by X-ray crystallography. The spectral and structural characterization as well as the magnetic behaviour of these complexes is reported. In this series, structures consist of the groups as counter ions and the bridging the two M(II) centers in a μ-1,3- (1-3) and in a μ-1,2-bis(monodentate) (4) bonding fashions. The coordination geometry around the Ni(II) ions in 1 and 2 is six-coordinate with distorted octahedral environment achieved by N atoms of the amines and by one or two oxygen atoms from coordinated water molecules, respectively. In the Cu(II) complexes 3 and 4, a distorted square pyramidal geometry is achieved by the three N-atoms of the aepn or DPA and by an oxygen atom from a coordinated water molecule. The electronic spectra of the complexes in aqueous solutions are in complete agreement with the assigned X-ray geometry around the M(II) centers. The complexes show weak antiferromagnetic coupling with ∣J∣ = 1.8-4.2 cm⁻¹ in the μ-1,3- bridged squarato compounds 1-3, and J = −16.1 cm⁻¹ in the corresponding μ-1,2- bridged squarato complex 4. The magnetic properties are discussed in relation to the structural data.     

Imidazolate-bridged dicopper(II) and copper(II)–zinc(II) complexes of macrocyclic ligand with methylimidazol pendants: Model study of copper(II)–zinc(II) superoxide dismutase

Two new homo- and hetero-dinuclear complexes, [Cu₂L(im)](ClO₄)₃4H₂O (1) and [CuZnL(im)](ClO₄)₃4H₂O (2) (where Im=1H-1midazole and L = 3, 6, 9, 16, 19, 22-hexaaza-6, 19-bis(1H-imidazol-4-ylmethyl)tricycle[22, 2, 2, 2^11,14]triaconta-1, 11, 13, 24, 27, 29-hexaene) were synthesized and characterized as model compounds for the active site of copper(II)–zinc(II) superoxide dismutase (Cu₂Zn₂–SOD). X-ray crystal structure analysis revealed that the metal centers in both complexes exhibit distorted trigonal-bipyramid coordination geometry and the CuCu and CuZn distances are both 6.02 Å. Magnetic and ESR spectral measurements of 1 showed antiferromagnetic exchange interactions between the imidazolate-bridged Cu(II) ions. The ESR spectrum of 2 displays typical signals of mononuclear Cu(II) complex, demonstrating the formation of heterodinuclear complex 2 rather than a mixture of homodinuclear Cu(II)/Zn(II) complexes. pH-dependent ESR and UV–visible spectral measurements manifest that the imidazolate exists as a bridging ligand from pH 6 to 11 for both complexes. The IC₅₀ values of 1.96 and 1.57 μM [per Cu(II) ion] for 1 and 2 suggest that they are good models for the Cu₂Zn₂–SOD.     

Synthesis and characterization of a high spin d Fe(II) complex with the tridentate ligand dipyrido(2,3-a:3,2-j)phenazine (dpop)

A new bis-(N-tridentate) Fe(II) complex [Fe(dpop^′)₂](PF₆)₂ (dpop^′=dipyrido(2,3-a:3^′,2^′-j)phenazine) was prepared and studied. The magnetic moment of the solid was determined as μ=5.2-4.9 BM and in CH₃CN solution as μ=4.9 BM and indicate the high spin Fe(II) state. The electronic absorption spectrum displays a broad weak absorption MLCT transition at 602 nm (ε=3.8×10³ M⁻¹ cm⁻¹), consistent with CT absorptions of other Fe(II) HS complexes. The cyclic voltammogram of the complex shows an irreversible Fe^2+/3+ oxidation at +1.55 V and two dpop^′0/−1 centered reductions at −0.20 and −0.59 V versus Ag/AgCl.     

DNA binding affinity of a macrocyclic copper(II) complex: Spectroscopic and molecular docking studies

The interaction of a novel macrocyclic copper(II) complex, ([CuL(ClO₄)₂] that L is 1,3,6,10,12,15-hexaazatricyclo[13.3.1.1^6,10]eicosane) with calf thymus DNA (ct-DNA) was investigated by various physicochemical techniques and molecular docking at simulated physiological conditions (pH = 7.4). The absorption spectra of the Cu(II) complex with ct-DNA showed a marked hyperchroism with 10 nm blue shift. The intrinsic binding constant (K_b) was determined as 1.25 × 10⁴ M^?1, which is more in keeping with the groove binding with DNA. Furthermore, competitive fluorimetric studies with Hoechst33258 have shown that Cu(II) complex exhibits the ability to displace the ct-DNA-bound Hoechst33258 indicating that it binds to ct-DNA in strong competition with Hoechst33258 for the groove binding. Also, no change in the relative viscosity of ct-DNA and fluorescence intensity of ct-DNA-MB complex in the present of Cu(II) complex is another evidence to groove binding. The thermodynamic parameters are calculated by van't Hoff equation, which demonstrated that hydrogen bonds and van der Waals interactions played major roles in the binding reaction. The experimental results were in agreement with the results obtained via molecular docking study.     

Synthesis of a new tetradentate bis(imino-phosphine) ligand and its complexation with copper(I) ions

Schiff base condensation of m-phenylenediamine with two equivalents of o-(diphenylphophino)benzaldehyde products the potentially tetradentate molecule 1,3-(Ph₂P(o-C₆H₄)CHN)₂C₆H₄ (1) in high yield. The reaction of 1 and [Cu(NCMe)₄]BF₄ affords the dinuclear complex [(1,3-(Ph₂P(o-C₆H₄)CHN)₂C₆H₄)₂Cu₂](BF₄)₂ (2) through coordination of the imino-phosphine groups. The structure of 2 has been determined by an X-ray diffraction study.