Synthesis,crystal structures,and properties of two heterometallic Cu(II)–M(II) (M = Zn,Ni) oxamidato-bridged coordination complexes

Two heterometallic coordination complexes, {[Cu(aeop)Zn(H₂O)₃]₂?·?3H₂O} _n (1) and [Cu(aeop)Ni(H₂O)₄]?·?4H₂O (2) (H₄aeop?=?N-(2-aminoterephthalic acid)-N′-(1,3-propanediamine)oxamidate), have been synthesized and characterized by elemental analyses, IR, UV spectroscopy, thermogravimetric analysis, and X-ray crystal diffraction. Complex 1 features a 1-D chain constructed from neutral tetranuclear units. Complex 2 is a neutral binuclear complex. Through intermolecular hydrogen-bonding interactions, 2 gives a 3-D network structure. The variable temperature magnetic susceptibility measurements (2–300?K) of 2 show a pronounced antiferromagnetic interaction between the copper(II) and nickel(II), and the exchange integral J is equal to ?42.7?cm^?1.     

Synthesis,DNA-binding,and photocleavage properties of Ru(II) complexes containing dppz-based ligand

A ligand ipdp (ipdp?=?indeno[1′,2′?:?5,6]pyrazino[2,3-i]dipyrido[3,2-a?:?2′,3′-c]phenazine-8-one) and its ruthenium complexes, [Ru(L)₂(ipdp)]²⁺ (L?=?bpy (2,2′-bipyridine), phen (1,10-phenanthroline)), have been synthesized and characterized by elemental analysis, electrospray mass spectra, and ¹H NMR. The interaction between the complexes and calf thymus DNA (CT-DNA) has been investigated by spectroscopic methods and viscosity measurements. The results indicate that the complexes can bind to CT-DNA in an intercalative mode. In addition, both complexes promote the photocleavage of plasmid pBR322 DNA under irradiation. The mechanistic studies reveal that singlet oxygen ¹O₂ plays a significant role in DNA photocleavage.     

Synthesis,characterization, antitumor,and cytotoxic activity of mononuclear Ru(II) complexes

In the search for antitumor active metal complexes several ruthenium complexes have been reported to be promising. A series of mononuclear Ru(II) complexes, [Ru(T)₂(S)]²⁺, where T?=?2,2′-bipyridine/1,10-phenanthroline and S?=?CH₃-bitsz, Cl-bitsz, Br-bitsz, tmtsz, dmtsz, have been prepared and characterized by UV-Vis, IR, ¹H-NMR, FAB-mass spectroscopy, and elemental analysis. The complexes were subjected to in vivo anticancer activity against a transplantable murine tumor cell line Ehrlich's ascitic carcinoma (EAC) and in vitro cytotoxic activity against human cancer cell line Molt 4/C₈, CEM, and murine tumor cell line L1210. Ruthenium complexes showed promising biological activity especially in decreasing tumor volume and viable ascitic cell counts. Treatment with these complexes prolonged the life span of EAC-tumor-bearing mice by 10–48%. In vitro evaluation of these ruthenium complexes revealed cytotoxic activity from 0.21 to 24?µmol?L^?1 against Molt 4/C₈, 0.16–19?µmol?L^?1 against CEM, and 0.75–32?µmol?L^?1 against L1210 cell proliferation, depending on the nature of the compound.     

Synthesis,characterization and biological activities of mononuclear and binuclear Fe(III) complexes with some symmetric and unsymmetric Schiff-base ligands

A series of mononuclear and binuclear Fe(III) complexes of some new symmetrical and unsymmetrical Schiff bases containing quinoline derivatives were synthesized and characterized by elemental and thermal analysis, conductance measurements and IR spectra. In mononuclear complexes, the unsymmetric Schiff bases are monobasic tetradentate towards the Fe(III) ion. However, in binuclear complexes, the symmetric Schiff-base ligands behave as monobasic bidentate towards each Fe(III) ion. The structure of the solid complexes are discussed and based on magnetic susceptibility measurements, electronic and ESR spectral studies. The biological activities of the ligands and their complexes are reported.     

Synthesis,spectroscopic characterization,in vitro cytotoxic and structure activity relationships of some mononuclear Ru(II) complexes

New mononuclear Ru(II) complexes [Ru(A)₂(B)]²⁺, where A?=?2,2′-bipyridine/1,10-phenanthroline and B?=?3,4,5-tri-OCH₃-DPC, 4-CH₃-DPC, 4-N(CH₃)₂-DPC, 4-NO₂-DPC, N-BITSZ, PTSZ and PINH, were prepared and characterized by spectroscopic methods. The in vitro cytotoxic activities of the complexes and their corresponding ligands were investigated against the human cancer T-lymphocyte cell lines molt 4/c8 and CEM and the murine tumor leukemia cell line L1210, human promyelocytic leukemia cells (HL-60) and Bel-7402 liver cancer cells by MTT assay. The complexes [Ru(A)₂(B)]²⁺ (A?=?1,10-phenanthroline, B?=?3,4,5-tri-OCH₃-DPC) exerts rather more potent activities against all of these cell lines, especially for CEM and L1210. Ru complexes and structure–activity relationships and anticancer mechanisms are also discussed.     

Syntheses,characterizations, and antimicrobial activities of binuclear ruthenium(III) complexes containing 2-substituted benzimidazole derivatives

Binuclear ruthenium(III) complexes [RuX₃L]₂?·?nH₂O (X?=?Cl, L?=?L¹, L², L³; n?=?1, L⁴ and L⁵, X?=?Br; L?=?L³), [RuX₃L_1.5]₂?·?nH₂O (X?=?Br, L?=?L¹; n?=?0, L⁴; n?=?6 and L⁵; n?=?10), and [RuX₃L₂]₂ (X?=?Br, L?=?L²) have been isolated by treatment of hydrated RuX₃ (X?=?Cl/Br) in acetone with 2-(2′-aminophenylbenzimidazole) (L¹), 2-(3′-aminophenylbenzimidazole) (L²), 2-[(3′-N-salicylidinephenyl)benzimidazole] (L³), 2-(3′-pyridylbenzimidazole) (L⁴), and 2-(4′-pyridylbenzimidazole) (L⁵) in acetone. The complexes were characterized by elemental analysis, conductivity and magnetic susceptibility measurements, IR, electronic, EPR, and mass spectral studies. The complexes were dimeric; based on analytical and spectral studies, an octahedral geometry was proposed for the complexes. The synthesized complexes were screened against Gram-positive and Gram-negative bacteria and fungi.     

Symmetric Ni(II) dithiocarbamates with bidentate phosphines ligands

Ni(II) mononuclear dithiocarbamate complexes with bidentate P,P ligands of composition [Ni(R₂dtc)(P,P)]X {R?=?pentyl (pe), benzyl (bz); dtc?=?S₂CN^?; P,P?=?1,2-bis(diphenylphosphino)ethane (dppe), 1,4-bis(diphenylphosphino)butane (dppb), 1,1′-bis(diphenylphosphino) ferrocene (dppf); X?=?ClO₄, Cl, Br, NCS} and binuclear complexes of composition [Ni₂(μ-dpph)(R₂dtc)₂]X₂ with a P,P-bridging ligand {P,P?=?1,6-bis(diphenylphosphino)hexane (dpph); X?=?Cl, Br, NCS} have been synthesized. The complexes have been characterized by elemental and thermal analysis, IR, electronic and ³¹P{¹H}-NMR spectroscopy, magnetochemical and conductivity measurements. Single crystal X-ray analysis of [Ni(pe₂dtc)(dppf)]ClO₄ confirmed a distorted square planar coordination in the NiS₂P₂ chromophore. For selected samples, the catalysis of graphite oxidation was studied.     

Vanadyl(IV) complexes of 4-alkoxy substituted [N,O] donor salicylaldimine Schiff bases derived from chloro-/nitro-aniline: synthesis,mesomorphism, and DFT study

Oxovanadium(IV)-Schiff-base complexes, [VOL₂] {L?=?N,N′-bis-(4-X-amino phenyl (4′-n-alkoxy)-salicylaldiminato), n?=?10, 18; X?=?Cl, NO₂}, have been synthesized from the interaction of vanadyl (VO²⁺) and the bidentate [N,O] donor in methanol/ethanol. The compounds were characterized by FT–IR, ¹H- and ¹³C-NMR, FAB-mass spectra, elemental analyses, and solution electrical conductivity. Mesomorphic behavior of the ligands and their vanadyl complexes were probed by polarizing optical microscopy and differential scanning calorimetry. The compounds are thermally stable and exhibit enantiotropic smectic A mesomorphism over the temperature range of 57–231°C. The mesophase–isotropic transition temperatures for the complexes are much higher than the ligands. Melting and clearing points of the compounds did not show any definitive trend with regards to alkoxy chain length or electronegative substituent. Variable temperature magnetic susceptibility measurements of the vanadyl complexes clearly show the absence of exchange interactions among the vanadyl spin centers. Non-electrolytic natures of the complexes were shown by conductometric measurements. A ν(V=O) of ～970?cm^?1 corroborated the absence of any V=O?···?V=O interactions. Density functional theory study carried out using DMol3 at BLYP/DNP level to determine the energy-optimized structure revealed a distorted square pyramidal geometry for the vanadyl complexes.     

Complexes of Rhodium(III) with Two Chelating C⁁N Ligands and One Diimine Ligand

The synthesis of two series of cyclometalated Rh^III compounds is described, namely of 5 dinuclear chlorobridged species [{Rh(C?N)₂} (μ-Cl)₂] A and of 15 mononuclear complexes [Rh(C?N)₂(N?N)]⁺ B ; C?N stands for five different cyclometalating ligands, i.e. deprotonated phenylpyridine, deprotonated 2-(thienyl)pyridine, and three deprotonated 1-aryl-1H-pyrazoles, and N?N for six diimine ligands such as 2,2-bihyridine, 2,2′-bi-1H-imidazole, and 2,2′-bipyrimidine. For (2,2′-bipyridine)bis[2-(thien-2-yl)pyridinato-N,C^3′]rhodium(III) chloride, an X-ray structure determination was carried out. In the other cases, ¹H-NMR spectra established the configuration of the complexes. All mononuclear and dinuclear complexes show a C,C cis-configuration. The UV/VIS-absorption bands at longest wavelength are most likely due to metal-to-ligand charge-transfer (MLCT) transitions, depending on the nature of the cyclometalating ligand C?N and on the diimine ligand N?N. The receptor orbital is in some cases on the cyclometalating ligand, in others on the diimine. All monomer complexes exhibit at least one reversible reduction wave in the cyclovoltammogram in dimethylformamide solutions, attributable to a ligand-centered reduction. It is, therefore, concluded that the LUMO in [Rh(C?N)₂(N?N)]⁺ is of L(π*) character, as opposed to [Rh(bpy)₃]³⁺, where it is a metal d-orbital. The crystal system of (2,2′-bipyridine)bis[2-(thien-2-yl)pyridinato-N,C_3′]rhodium(III) chloride—water (1/2.125) is tetragonal (space group P⁴; R = 0.036, R_w = 0.040). The Rh-atom has slightly distorted octahedral environment; the average distances are (Rh? N/thienyl? pyridine) = 2.060 (3), Rh? C = 1.9885 (3), and Rh? N(bipyridine) = 2.1415 (3) Å. Of the three ligands the 2,2′-bipyridine is the most planar.     

Effects of electron-rich ancillary ligands on green and yellow-emitting bis-cyclometalated iridium complexes

Abstract

Six new green to yellow-emitting heteroleptic bis-cyclometalated iridium(III) complexes of the type Ir(C?N)₂(L?X) (C?N?=?cyclometalating ligand, L?X?=?monoanionic chelating ancillary ligand) bearing two widely used cyclometalating ligands (C?N?=?2-(2-thienyl)pyridine (thpy) and 2-phenylbenzoxazole (bo)) and six different ancillary ligands were prepared. In this study, the complexes include structurally diverse ancillary ligands that allow us to investigate several aspects of structure-property relationships. Ancillary ligands used in this study are small-bite-angle N-phenylacetamidate (paa), N-isopropylbenzamidate (ipba) and N,N′-diisopropylbenzamidinate (dipba), and larger bite-angle β-ketoiminate (acNac), β-diketiminate (NacNac), and β-thioketoiminate (SacNac). The emission color is governed by the choice of the cyclometalating ligand, but the ancillary ligands influence the electrochemical and photophysical properties. Electrochemical analysis shows that the energy of the HOMO varies substantially as the L?X structure is altered, whereas the energy of LUMO remains nearly constant. The emission maxima range from 537?nm to 590?nm, with solution quantum yields between 0.0094 and 0.60 and microsecond lifetimes. The results here reveal the ancillary ligands provide a channel to control redox properties and excited-state dynamics in cyclometalated iridium complexes that luminesce in the middle regions of the visible spectrum.     

Potentiometric studies of the interaction of amine-bridged dinuclear palladium(II) complex with nitrogen bases

Complexes formed by interaction of trans-diamminepalladium(II) chloride (Pd^II) with 1,6-hexanediamine (HDA) and nitrogen bases (B) (imidazole derivatives or methylamine) are investigated at 25°C and 0.1?mol?L^?1 NaNO₃ ionic strength using potentiometric measurements. The stability constants of all possible mononuclear and binuclear complexes were determined. The concentration distribution diagram of the binuclear Pd^II-HDA-Im derivative reveals the complexes predominating in the physiological pH range; the reaction of the binuclear Pd^II-HDA-Pd^II with imidazole derivatives is quite feasible.     

Ionic liquids from the cationic cobalt(III) Schiff base complex, [Co(acacen)L2][Tf2N] (acacen = N,N′-bis(acetylacetone)ethylenediamine,Tf2N = bis(trifluoromethanesulfonyl)amide)

Ionic liquids comprising cationic cobalt(III) complexes [Co(acacen)L₂][Tf₂N] (L?=?3-butylpyridine (1), 1-butylimidazole (2); acacen?=?N,N′-bis(acetylacetone)ethylenediamine, Tf₂N?=?bis(trifluoromethanesulfonyl)amide) were prepared. 1 is a liquid at room temperature and exhibits a glass transition at ?12?°C, whereas 2 is a solid at room temperature with a melting point of 74.6?°C and glass transition temperature of ?15?°C upon cooling from the melt. These salts are reddish brown diamagnetic materials that are stable against air and water; these properties differ from those of the corresponding iron(III) salt. Desorption of the axial ligands of 1 and 2 occurs at 180 and 207?°C, respectively.     

Spectroscopic characterization and electrochemical studies of ruthenium(II) carbonyl complexes containing bidentate Schiff bases and triphenylphosphine or a nitrogen heterocycle

Reactions of ruthenium(II) carbonyl complexes of the type [RuHCl(CO)(PPh₃)₂(B)] [B?=?PPh₃, pyridine (py), piperidine (pip) or morpholine (mor)] with bidentate Schiff base ligands derived from the condensation of 2-hydroxy-1-naphthaldehyde with aniline, o-, m- or p-toluidine in a 1?:?1 mol ratio in benzene resulted in the formation of complexes formulated as [RuCl(CO)(L)(PPh₃)(B)] [L?=?bidentate Schiff base anion, B?=?PPh₃, py, pip, mor]. The complexes were characterized by analyses, IR, electronic and ¹H NMR spectroscopy, and cyclic voltammetric studies. In all cases, the Schiff bases replace one molecule of phosphine and a hydride ion from the starting complexes, indicating that Ru–N bonds in the complexes containing heterocyclic nitrogenous bases are stronger than the Ru–P bond to PPh₃. Octahedral geometry is proposed for the complexes.     

Honeycomb‐like Ordered Assembly of DNA Induced by Flexible Binuclear Ruthenium(II)–Polypyridyl Complexes

A series of binuclear ruthenium(II)–polypyridyl complexes of the type [Ru₂(N‐N)₄(BPIMBp)]⁴⁺, in which N‐N is 2,2′‐bipyridine (bpy; 1 ), 1,10‐phenanthroline (phen; 2 ), dipyrido[3,2‐d:2′,3‐f] quinoxaline (dpq; 3 ), dipyrido[3,2‐a:2′,3′‐c] phenanzine (dppz; 4 ), and 1,4′‐bis[(2‐pyridin‐2‐yl)‐1H‐imidazol‐1‐yl)methyl]‐1,1′‐biphenyl (BPIMBp) is a bridging ligand, have been synthesized and characterized. These complexes are charged (4+) cations and flexible due to the ?CH₂ group of the bridging ligand and possess terminal ligands with variable intercalative abilities. The interaction of complexes 1 – 4 with calf thymus DNA (CT‐DNA) was explored by using UV/Vis absorption spectroscopy, steady‐state emission, emission quenching with K₄[Fe(CN)₆], ethidium bromide displacement assay, Hoechst displacement assay, and viscosity measurements and revealed a groove‐binding mode for all the complexes through a spacer and an intercalative mode for complexes 3 and 4 . A decrease in the viscosity of DNA revealed bending and coiling of DNA, an initial step toward aggregation. Interestingly, a distinctive honeycomb‐like ordered assembly of the DNA–complex species was visualized by fluorescence microscopy in the solution state. The use of SEM and AFM confirmed the disordered self‐organization of the DNA–complex adduct on evaporation of the solvent. The small orderly nanosized DNA aggregates were confirmed by means of circular dichroism, dynamic light scattering (DLS), and TEM. These complexes are moderately cytotoxic against three different cell lines, namely, MCF‐7, HeLa, and HL‐60.     

Preparation and molecular structures of N,N-2,2′-dipicolyl- and N,N-3,3′-dipicolyldithiocarbamato metal complexes

New iron(III) and cobalt(III) complexes, [Fe(2,2′-dpdtc)₃], [Fe(3,3′-dpdtc)₃], [Co(2,2′-dpdtc)₃], and [Co(3,3′-dpdtc)₃] (dpdtc?=?dipicolyldithiocarbamate) have been synthesized and their molecular structures and spectroscopic properties determined. The 2,2′- and 3,3′-dpdtc ligands have four donors, S, S′, N, and N′. These complexes are insoluble in water, but soluble in acidic solution. Crystal structures of these metal complexes reveal that the central metal ions have MS₆ (M?=?Fe and Co) octahedral structures and all dipicolyl groups do not coordinate.     

Synthesis,electrochemical and antimicrobial studies of mono and binuclear iron(III) and oxovanadium(IV) complexes of [ONO] donor tridentate Schiff-base ligands

Tridentate Schiff bases (H₂L¹ or H₂L²) were derived from condensation of acetylacetone and 2-aminophenol or 2-aminobenzoic acid. Binuclear square pyramidal complexes of the type [M₂(L¹)₂]?·?nH₂O (M?=?Fe–Cl, n?=?0; M?=?VO, n?=?1) were accessed from interaction of H₂L¹ with anhydrous FeCl₃ and VOSO₄?·?5H₂O, respectively. A similar reaction with H₂L², however, produced mononuclear complexes [ML²(H₂O) _x ]?·?nH₂O (M=Fe–Cl, x?=?0, n?=?0; M=VO, x?=?1, n?=?1). The compounds were characterized using elemental analysis, FT-IR, UV-Vis, and NMR (for ligand only), and mass spectroscopies and solution electrical conductivity studies. Magnetic susceptibility measurements suggest antiferromagnetic exchange in binuclear Fe(III) and VO(IV) complexes. Thermo gravimetric analysis (TGA) provided unambiguous evidence for the presence of coordinated as well as lattice water in [VOL²(H₂O)]?·?H₂O. Cyclic voltammetric studies showed well-defined redox processes corresponding to Fe(III)/Fe(II) and VO(V)/VO(IV). In vitro antimicrobial activities of the compounds were investigated against Klebsiella pneumoniae, Staphylococcus aureus, Pseudomonas aeroginosa, Escherichia coli, Bacillus subtilis, and Proteus vulgaris. H₂L¹ and its binuclear complexes exhibited pronounced activity against all the microorganisms tested.     

Mononuclear,homo- and hetero-binuclear complexes of 1-(5-(1-(2-aminophenylimino)ethyl)-2,4-dihydroxyphenyl)ethanone: synthesis,magnetic, spectral,antimicrobial, antioxidant,and antitumor studies

A new Schiff base, H₂L, was prepared by condensation of 4,6-diacetylresorcinol with o-phenylenediamine in molar ratio 1?:?1. The ligand reacted with copper(II), nickel(II), cobalt(II), iron(III), zinc(II), oxovanadium(IV), and dioxouranium(VI) ions in the absence and presence of LiOH to yield mononuclear and homobinuclear complexes. The mononuclear dioxouranium(VI) complex [(HL)-(UO₂)(OAc)(H₂O)]·5H₂O was used to synthesize heterobinuclear complexes. The ligand and its metal complexes were characterized by elemental analyses, IR, ¹H-, and ¹³C-NMR, electronic, ESR and mass spectra, conductivity, and magnetic susceptibility measurements as well as thermal analysis. In the absence of LiOH, mononuclear complexes (1, 4, and 9) were obtained; in the presence of LiOH, binuclear complexes (3, 5, 7, and 10) as well as mononuclear complexes (2, 6, and 8) were obtained. In the mononuclear complexes, the coordinating sites are the phenolic oxygen, azomethine nitrogen, and amino nitrogen. In addition to these coordinating sites, the free carbonyl and phenolic OH are involved in coordination in binuclear complexes. The metal complexes exhibited octahedral, tetrahedral, and square planar geometries while the uranium is seven-coordinate. The antimicrobial and antioxidant activities of the ligand and its complexes were investigated. The ligand and the metal complexes showed antitumor activity against Ehrlich Acites Carcinoma.     

Synthesis,DNA-binding,and photocleavage studies of ruthenium(II) complexes with an asymmetric ligand

An asymmetric ligand (pdpiq?=?2-(pyridine-2-yl)-6,7-diphenyl-1-H-imidazo[4,5-g]quinoxaline) and its ruthenium complexes with [Ru(L)₂pdpiq]²⁺ (L?=?bpy (2,2′-bipyridine) or phen (1,10-phenanthroline)) have been synthesized and characterized by elemental analysis, ES-MS, and ¹H NMR. The DNA-binding behaviors of these complexes were studied by spectroscopic methods and viscosity measurements. The results indicate that the complexes can intercalate into DNA base pairs. When irradiated at 365?nm, the two complexes promote the cleavage of plasmid pBR322DNA. The mechanism of DNA cleavage is an oxidative process by generating singlet oxygen.     

Ruthenium complexes of hexakis(cyanophenyl)[3]radialenes and their di(cyanophenyl)methane precursors: synthesis,photophysical, and electrochemical properties

The coordination chemistry of cross-conjugated ligands and the effect of cross-conjugation on the nature of metal–metal and metal–ligand interactions have received limited attention. To explore the effects of cross-conjugation eight ruthenium complexes were synthesized, mononuclear complexes of two isomeric cross-conjugated [3]radialenes [RuCp(PPh₃)₂(L)]PF₆ and [{RuCp*(dppe)}(L)]PF₆ (L?=?hexakis(4-cyanophenyl)[3]radialene, 2; hexakis(3-cyanophenyl)[3]radialene, 3), and dinuclear complexes [{RuCp(PPh₃)₂}₂(L)](PF₆)₂ and [{RuCp*(dppe)}₂(L)](PF₆)₂ of the diarylmethane precursors (L?=?4,4′-dicyanodiphenylmethane, 4; 3,3′-dicyanodiphenylmethane, 5) to the [3]radialenes. Considerable synthetic challenges allowed only clean isolation of mononuclear complexes of the multidentate radialenes 2 and 3. As expected, coordinating a positively charged metal induces a red shift for the π–π* transition in complexes of ligand 2, but unexpectedly a blue shift for the same transition in complexes of 3 was observed. This points to conformational differences for the [3]radialene in the ruthenium complexes of the para- (2) versus meta- (3) substituted hexaaryl[3]radialenes. Cyclic voltammetry indicates that the methylene spacer in 4 and 5 does not enable any interaction between metal centers and the absorption behavior is essentially as observed for [Ru(NCPh)(PPh₃)₂Cp]PF₆ and [Ru(NCPh)(dppe)Cp*]PF₆ but generally with a slight red shift in absorbance maxima.     

Mono- and binuclear copper(II) complexes of saccharin with 2-pyridinepropanol synthesis,spectral, thermal and structural characterization

Mono- and binuclear copper(II) saccharinate (sac) complexes containing 2-pyridinepropanol (pypr) have been prepared and characterized by elemental analyses, i.r., u.v.–vis., magnetic measurements and single crystal X-ray diffraction. The copper(II) ion in trans-[Cu(pypr)₂(sac)₂] has –1 site symmetry and is octahedrally coordinated by two bidentate neutral pypr (N, O) and two sac (O) ligands. The binuclear copper(II) complex, [Cu₂(-pypr)₂(sac)₂], is built up around a centre of symmetry and contains two strongly distorted square–planar coordinated copper(II) ions bridged by two alkoxo groups of the deprotonated pypr ligand, which also coordinates to the copper(II) ions through its nitrogen. In contrast to the mononuclear complex, the sac ligands in the binuclear complex is N-coordinated. The binuclear complex exhibits diamagnetic behaviour. The i.r. spectra and thermal decompositions of both complexes are described.