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Two new copper(ii) polymeric complexes, {[Cu(HPymat)(H2O)](NO3)}n (1) and [Cu2(Pymat)2(H2O)3]n (2), have been synthesized using the Schiff base ligand H2Pymat [H2Pymat = (E)-2-(1-(pyridin-2-yl)-methyleneamino)terephthalic acid]. Complex 1 is a cationic 1D polymer, whereas complex 2 is a two dimensional polymer. Both complexes were crystallographically, spectroscopically and magnetically characterized. Theoretical studies were performed and the catecholase activity of the complexes was also examined. Complex 1 is a ferromagnetically coupled complex with J = 2.8 cm-1 and 2 shows antiferromagnetic coupling with J = -1.6 cm-1. Both complexes show notable features in the EPR study. They show rhombic spectra at 77 K in the solid state, but by varying the temperature or solvents the nature of the spectra can be changed or inverted. This behaviour indicates a change of the ground state from dx2-y2 to dz2 orbitals. Theoretical calculations of 1 focus on the evaluation and characterization of interesting anion-π-anion assemblies that are formed in the solid state. In 2 we have analysed the unconventional chelate ringchelate ring π-stacking interactions that govern its solid state architecture. Both complexes act as functional models and show catechol oxidase activity with a kcat value of the order of 103 h-1.

Two copper(II) polymeric complexes {[Cu(HPymat)(MeOH)](NO3)}n (1) and {[Cu4(Pymab)4(H2O)4](NO3)4} (2) were synthesized with the carboxylate-containing Schiff-base ligands HPymat(-) and Pymab(-) [H2Pymat = (E)-2-(1-(pyridin-2-yl)methyleneamino)terephthalic acid, HPymab = (E)-2-((pyridine-2-yl)methyleneamino)benzoic acid]. Complex 1 is a one-dimensional Cu(II) cationic polymeric complex containing free protonated carboxylic groups and nitrate anions as counterions. Complex 2 is a zero-dimensional tetranuclear cationic Cu(II) complex containing nitrate anions as counterions. Complex 1 shows rhombic electron paramagnetic resonance (EPR) spectra in the solid state at room temperature (RT) and 77 K and tetragonal EPR spectra in dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) and "inverse" EPR spectrum in CH3CN. Complex 2 shows rhombic EPR spectra in the solid state at RT and 77 K. But complex 2 shows tetragonal spectra in DMSO, DMF, and CH3CN. Thermogravimetric analysis was also performed for both complexes 1 and 2. Mean-square displacement amplitude analysis was carried out to detect librational disorder along the metal-ligand bonds in crystal structures.

A novel type of C-H/σ supramolecular interaction involving σ-aromatic M2X2 (M = Cu, Hg; X = Cl, Br, I, S) cores is reported for the first time. Three new polymeric coordination copper complexes, {[Cu(μ-Cl)(Cl)(μ-L)]2}n (1), {[Cu(μ-I)(μ-L)]2}n (2) and [Cu(Br)2(μ-L)(CH3CN)2]2 (3), have been synthesized with the organic ligand α,ω-bis(benzotriazoloxy)propane system (L) and halides as counterions. A very interesting C-H/σ supramolecular interaction has been observed in the solid state structure of compound 2, similar to a C-Hπ interaction, which has been confirmed by Bader's "atoms-in-molecules" AIM analysis. The Nucleus Independent Chemical Shift (NICs) method was used to evaluate the aromatic character of the different cores in this study. The influence of the nature of the metal ions, bridging atoms, oxidation states, and coordination environments around the metal centers on the strength of the aromaticity of the M2X2 cores was theoretically analyzed and explained. The binding ability of the 1-alkoxy-1,2,3-benzotriazole ring to establish π-π and C-H/π interactions and how its coordination to Cu(I) and Cu(II) ions affects the strength of the aforementioned interactions have been discussed. The electron deficient triazole ring and its π-acidity increases upon coordination of the Cu ion, leading to the formation of a lone pair (lp)-π interaction involving the five-membered ring of the ligand, which has also been analyzed. We have also analyzed the C-H/σ interactions of previously reported X-ray crystal structures of different coordination polymers based on a binuclear copper(I) complex and 2,3-dimethylpyrazine, dithioethers, and benzotriazol-1-yl-based pyridyl units as ligands using I- as a counter-ion. Complex 1 shows antiferromagnetic behavior with a magnetic coupling constant of J = -7.9 cm(-1). Moreover, photoluminescence and TGA studies of the complexes were also carried out.

Two new N3O donor ketoxime Schiff bases (HL(1) and HL(2)) have been synthesized by condensing N,N-dimethylethylenediamine with diacetylmonoxime and benzilmonoxime, respectively in a 1:1 ratio. Reaction of Cu(ClO4)2·6H2O with HL(1) resulted in a discrete oximato-bridged dinuclear Cu(II) complex [Cu2(L(1))2(H2O)2](ClO4)2 (1). The same reaction in presence of NaSCN affords the complex {[Cu(II)2(L(1))2][Cu(I)4(μ(1,3)-SCN)4(μ(1,1,3)-SCN)2]}n (2), where partial Cu(II)→Cu(I) reduction is observed. In 2, arrays of [Cu(II)2(L(1))2](2+) cationic units are inserted in between 2D {[Cu(I)4(SCN)6](2-)}n layers and connected via μ(1,1,3)-SCN(-) links, thus forming a 3D network. On the other hand, reaction of Cu(CH3COO)2 and HL(2) in the presence of NaSCN gave rise to a mixed-valence pentanuclear cluster {[Cu(II)2(L(2))2(NCS)]2[Cu(I)(SCN)(μ(1,1)-SCN)(μ(1,3)-SCN)]} (3) where Cu(II) is also partly reduced to Cu(I). In compound 3, two cationic [Cu(II)2(L(2))2(NCS)](+) units are bridged by the anionic [Cu(I)(SCN)3](2-) unit through long Cu-SCN linkages. The ligands and the complexes have been characterized by elemental analysis, UV/Vis and IR spectroscopy. The complexes are further characterized by single crystal X-ray diffraction and variable temperature magnetic (VTM) studies. Finally a complete magneto-structural correlation has been established between compounds 1-3 and all the characterized Cu dimers with a double NO bridge.

An easy reversible switching of the electronic ground state in a pentacoordinated copper(II) complex is reported for the first time. The simple protonation of a carboxylic group in a Cu(II) complex with a {dx(2)-y(2)}(1) electronic configuration leads to a flip of the ground electronic configuration from {dx(2)-y(2)}(1) to {dz(2)}(1) in the metal ion.

A mixed valent copper complex [Cu(II)Cu(I)(L)(μ-SCN)(μ(3)-SCN)](n) (LH = N'-((pyridin-2-yl)methylene)acetohydrazide) has been synthesized and characterized. It is a unique example of a 2D mixed valent Cu(II)-Cu(I) interlinked molecular assembly with a very unusual bridging property of the hydrazone ligand. An extraordinary in situ partial Cu(II)→ Cu(I) reduction is observed in this system at room temperature.

Syntheses and crystal structures of four new hydrazone-based Cu(ii) complexes, [{Cu(L(1))(H(2)O)}(2)(mu-pyraz)](ClO(4))(2) (), [{Cu(L(1))(OClO(3))}(2)(mu-4,4'-bipy)] (), [{Cu(L(2)H)}(mu-pyraz){Cu(L(2)H)(OClO(3))}].(ClO(4)) () and [{Cu(L(2))}(2)(mu-bpe)] () [L(1)H = condensation product of benzhydrazide and pyridine-2-carbaldehyde and L(2)H(2) = condensation product of benzoyl acetone and benzhydrazide], bridged by various organic spacers [pyrazine (pyraz), 4,4'-bipyridine (4,4'-bipy) and 1,2-di(4-pyridyl)ethane (bpe)] are reported in this paper. The single-crystal X-ray crystallographic studies reveal that all are dinuclear units where and form strong intermolecular H-bonding to form sheets of interconnected ions, whereas forms sheets of dinuclear chains through pi-pi interactions; in , molecules are linked only through van der Waals interactions. The variable-temperature magnetic moment studies reveal that and show antiferromagnetic coupling between the Cu(ii) centers at lower temperatures. The binding ability of with calf thymus DNA [CT-DNA] is reported using various spectroscopic studies (UV-Vis titration, circular dichroism and fluorescence). The binding constants of with CT-DNA, as calculated by different methodologies, are of the order of 10(5) M(-1). The mode of interaction between and CT-DNA has been predicted using circular dichroic (CD) spectroscopy, where it has been shown that most probably interacts with DNA via intercalation between the base pairs leading to a change in B-DNA conformation. is also able to cleave supercoiled (SC) plasmid DNA pUC19 in a time and dose dependent manner as demonstrated by agarose gel electrophoresis, and also demonstrates its potential to cleave the SC plasmid DNA via both oxidative and hydrolytic mechanisms. Approximately 50% of leukemic cells are found to be dead when two representative leukemic cell lines are exposed to ( approximately 80 muM) even for 24 h as determined by different cell cytotoxicity assays. Preliminary results also showed that, at 20 muM, could selectively induce apoptosis in leukemic cells without affecting normal lymphocytes.

Atmospheric CO2 fixation by an aqueous solution containing Cu(ClO4)2.6H2O and 4-aminopyridine (4-apy) yields a novel example of a two-dimensional mu3-CO3 bridged copper(II) complex {[Cu(4-apy)2]3(mu3-CO3)2(ClO4)2.(1/2)CH3OH}n that has been characterized by IR, UV and X-ray crystallography; preliminary magnetic measurements show that complex exhibits long-range ordered ferromagnetic coupling.

The 1D polymer complex [Cu2(L)2(SCN)2]n (1) has been syn-thesised in a one-step in situ reaction of picolinaldehyde with sodium thiocyanate. The complex 1 was characterised by FTIR spectroscopy, UV/Vis spectrophotometry and elemental analysis. The crystal structure of complex 1 shows that chains of dimer complexes are formed with tetra- and pentacoordi-nate copper centres alternately linked by one thiocyanato and two alkoxido bridges. Variable-temperature magnetic measurements showed a strong antiferromagnetic interaction between the copper centres within the dimer mediated by the two alkoxido bridges with a J value of -374 cm-1, which is in agreement with the DFT-calculated value of -284 cm-1. EPR and cyclic voltammetric analyses were also carried out, as well as DFT calculations to evaluate the packing forces and their energies. [ABSTRACT FROM AUTHOR]

A novel type of C–H/σ supramolecular interaction involving σ-aromatic M2X2 (M = Cu, Hg; X = Cl, Br, I, S) cores is reported for the first time. Three new polymeric coordination copper complexes, {[Cu(μ-Cl)(Cl)- (μ-L)]2}n (1), {[Cu(μ-I)(μ-L)]2}n (2) and [Cu(Br)2(μ-L)(CH3CN)2]2 (3), have been synthesized with the organic ligand α,ω-bis(benzotriazoloxy)propane system (L) and halides as counterions. A very interesting C–H/σ supramolecular interaction has been observed in the solid state structure of compound 2, similar to a C–H⋯π interaction, which has been confirmed by Bader’s “atoms-in-molecules” AIM analysis. The Nucleus Independent Chemical Shift (NICs) method was used to evaluate the aromatic character of the different cores in this study. The influence of the nature of the metal ions, bridging atoms, oxidation states, and coordination environments around the metal centers on the strength of the aromaticity of the M2X2 cores was theoretically analyzed and explained. The binding ability of the 1-alkoxy-1,2,3-benzotriazole ring to establish π–π and C–H/π interactions and how its coordination to Cu(I) and Cu(II) ions affects the strength of the aforementioned interactions have been discussed. The electron deficient triazole ring and its π-acidity increases upon coordination of the Cu ion, leading to the formation of a lone pair (lp)–π interaction involving the five-membered ring of the ligand, which has also been analyzed. We have also analyzed the C–H/σ interactions of previously reported X-ray crystal structures of different coordination polymers based on a binuclear copper(I) complex and 2,3-dimethylpyrazine, dithioethers, and benzotriazol- 1-yl-based pyridyl units as ligands using I− as a counter-ion. Complex 1 shows antiferromagnetic behavior with a magnetic coupling constant of J = −7.9 cm−1. Moreover, photoluminescence and TGA studies of the complexes were also carried out. [ABSTRACT FROM AUTHOR]

Three new hetero-bimetallic coordination complexes [Na(CuII L1)2](ClO4) ·0.5H2O ( 1), [Na(CuII L2)2][CuI2(μ1,3-NCS)3] n ( 2), and {[Na(CuII L3)2](μ1,5-dca)} n ( 3; dca = dicyanamide) have been synthesized by using different Schiff base ligands [e.g., L1H2 = N, N′-bis(3-methoxysalicylidenimino)-1,3-diaminopentane, L2H2 = N, N′-bis(3-ethoxysalicylidenimino)-1,3-diaminopropane, and L3H2 = N, N′-bis(5-bromo-3-methoxysalicylidenimino)-1,3-diaminopropane] in the presence of pseudohalide coligands N3-, SCN-, and N(CN)2- (dca), respectively. The ligands and the complexes have been characterized by microanalytical and spectroscopic techniques. The structures of the complexes, determined by single-crystal X-ray diffraction studies, show that in all cases a trinuclear Na(CuII L)2 unit is formed, but of different configurations. 1 does not include N3- anions. In contrast, in 2, SCN- extrudes partial in situ reduction of CuII to lead to the formation of an infinite [CuI2(μ1,3-NCS)3] n anionic chain; and in 3, N(CN)2- bridges the metal-ligand assemblies to form a 1D polymeric chain. ESI-MS, UV/Vis spectroscopy, and cyclic voltammetry were performed to investigate the solution-state behavior of the complexes. Theoretical calculations of the optimized geometries of the complexes were carried out at the BLYP/DNP level to determine their relative stabilities from the HOMO-LUMO gap and chemical softness values. [ABSTRACT FROM AUTHOR]

By slightly changing the synthetic conditions, we have prepared two closely related linear tetranuclear CuII complexes with the symmetrical ONNO donor tetradentate Schiff-base ligand [H2L = (OH)C6H4(CH3)C＝N(CH2)3N＝C(CH3)C6H4(OH)] and with azide ions. These two distinctly coloured crystalline products were characterized by elemental analysis, IR and UV–Vis spectroscopy, CV, EPR spectra and variable temperature magnetic measurements. Single crystal X-ray diffraction studies of the green [Cu4(μ-L)2(μ1,1-N3)2(N3)2] (1) and the red [Cu4(μ-L)2(μ1,1-N3)2(N3)2(H2O)2] (2) crystals show that the coordination environment of the two μ-phenoxo and μ1,1-azido bridged isomorphous tetranuclear CuII complexes are slightly different. Thus, both complexes are formed by very similar building units, although with a significant variation in the bridging Cu–O(phenoxo)–Cu and Cu–N(azido)–Cu bond angles. The consequences of these structural variations on the magnetic properties have been investigated from both the experimental and theoretical points of view by variable temperature magnetic measurements and DFT calculations. [ABSTRACT FROM AUTHOR]

Abstract: A novel hydroxo-bridged cyclic tetranuclear copper(II) complex with the guanazole ligand (3,5-diamino-1,2,4-triazole=Hdatrz), [Cu4(datrz)4(μ2-OH)2(NO3) (H2O)6]·(NO3) ·5(H2O) (1) has been synthesised and characterised by X-ray crystallography. In 1, the four copper(II) centres are linked by hydroxo bridges and the N1,N2-coordination of the deprotonated guanazole ligands. The core has considerably short Cu⋯Cu distances in the range of 3.3550(4)–3.3611(4)Å. Thermal analysis of 1 reveals that the cyclic framework constructed with hydroxo and guanazole ligands is stable up to 285°C. [Copyright &y& Elsevier]

Two new dicyanamide bridged 1D polynuclear copper(II) complexes [Cu(L1){μ1,5-N(CN)2}]n (1) [L1H=C6H5C(O)NHNC(CH3)C5H4N] and [Cu(L2){μ1,5-N(CN)2}]n (2) [L2H=C6H5C(O)CHC(CH3)NCH2CH2N(CH3)2] have been synthesised and structures of both the complexes and their crystal packing arrangements have been established by X-ray crystallography. For complex 1, a tridentate hydrazone ligand (L1H) obtained by the condensation of benzhydrazide and 2-acetylpyridine is used, whereas a tridentate Schiff base (L2H) derived from benzoylacetone and 2-dimethylaminoethylamine is employed for the preparation of complex 2. Variable temperature magnetic susceptibility measurement studies indicate there are weak antiferromagnetic interactions with J values −0.10 and −1.41cm−1 for 1 and 2, respectively. [Copyright &y& Elsevier]

A new mixed ligand copper(II) complex, [Cu(2,4-pydc)(pic)(H2O)] · H2O (1) (where 2,4-pydc = pyridine-2,4-dicarboxylate, pic = 2-picolylamine) has been synthesized and characterized by elemental analysis, FT-IR and UV-Vis spectroscopic and thermogravimetric methods. Single crystal X-ray diffraction analysis reveals that copper(II) atom in the title complex adopts distorted square-pyramidal geometry. Structural characterization also reveals that interplay of O-H...O, N-H...O, C-H...O, and C-H...π interactions between lattice and coordinated water and ligands significantly contribute to the crystal packing leading to the formation and strengthening of three dimensional supramolecular assembly. Hirshfeld surface analysis employing 3D molecular surface contours and 2D fingerprint plots have been used to analyze intermolecular interactions present in the solid state of the crystal. [ABSTRACT FROM AUTHOR]

Abstract: The trinuclear complex [L2Cu3(CF3CO2)4] (1) has been synthesized and its crystal structure determined. It consists of a linear arrangement of Cu(II) centers. The central copper atom is bonded to six oxygen atoms and has a tetragonally distorted octahedral geometry, while the terminal copper atoms are bonded to three oxygen and two nitrogen atoms and show a distorted square pyramidal geometry. The complex shows di-μ(O,O′) syn–syn carboxylate bridging as well as monoatomic (μ-O) bridging, along with phenolate (μ-O) oxygen bridging. Cryomagnetic investigations in the range 2–300K revealed an antiferromagnetic spin exchange interaction with J =−95.7cm−1, based on the isotropic exchange model H ex =−2J[S 1 · S 2 + S 2 · S 3]. [Copyright &y& Elsevier]

A novel hexanuclear complex [{(CuL)2Cu}2(μ-dca)2](ClO4)2·2L′(1) (where H2L=(OH)C6H4C(CH3)=N(CH2)3N=C(CH3)C6H4(OH) or N,N′-bis(2-hydroxyacetophenone) propylenediimine and dca=N(CN)2− and L′=2-hydroxyacetophenone) has been synthesized and characterized by elemental analysis, UV–Vis, FT-IR spectroscopic and electrochemical methods. Single crystal X-ray structural characterization reveals a centrosymmetric nature of the complex unit, where the metal centers adopt distorted square-planar and distorted octahedral geometries. Structural analysis also reveals μ2-phenoxo bridges between terminal and the central copper(II) centers of the asymmetric [(CuL)2Cu(dca)] unit, the latter being interconnected to its symmetry related counterpart by double μ1,5-dca bridges, leading to the hexanuclear complex ion [{(CuL)2Cu}2(μ-dca)2]2+. Low temperature susceptibility measurements of 1 revealed the presence of strong antiferromagnetic coupling (2J = −407cm−1) between the copper(II) centers. [Copyright &y& Elsevier]

Abstract: Three new Cu(II) complexes of formula [Cu(L1)(pyz)(CH3OH)]ClO4 (1), [Cu(L1)(4,4′-bpy)(ClO4)]·0.5H2O (2) and [{Cu(L2)(ClO4)}2(μ-4,4′-bpy)] (3) have been synthesised by using pyrazine (pyz) and 4,4′-bipyridine (4,4′-bpy) and tridentate O,N,O-donor hydrazone ligands, L1H and L2H, obtained by the condensation of 1,1,1-trifluoro-2,4-pentanedione with salicyloylhydrazide and benzhydrazide, respectively. The ligands and their complexes have been characterized by elemental analyses, FT-IR, and UV–Vis spectroscopies. Single crystal X-ray structure analysis evidences the metal ion in a slightly deformed square pyramidal geometry in all the complexes. However complexes 1 and 2 are mononuclear with pyz and 4,4′-bpy, respectively, showing an unusual monodentate behavior, while complex 3 is dinuclear with 4,4′-bpy adopting the typical bridging coordination mode. Self assembly of the complex units by hydrogen bonding interactions produces one-dimensional arrangement in each crystal packing. The magnetic characterization of complex 3 indicates a weak antiferromagnetic exchange interaction between the Cu(II) ions (J =−0.96cm−1) mediated through the long 4,4′-bpy bridge. Electrochemical behavior of the complexes is also discussed. [Copyright &y& Elsevier]

Abstract: Two new cyano bridged Cu–Co and Cu–Fe trinuclear bimetallic assemblies, [(CuL)[Co(CN)6](CuL)]ClO4 ·3.5H2O (1) and [(CuL)[Fe(CN)6](CuL)]·13H2O (2) where [L=(3E,5E)-N 1,N 4-bis((pyridin-2-yl)methylene)butane-1,4-diamine] have been prepared using cyanometallates as anion precursors and characterised by elemental analyses, spectroscopic studies, single crystal X-ray diffraction and cryomagnetic susceptibility measurements. Magneto-structural correlations have been drawn from cryomagnetic susceptibility measurements over a wide temperature range (2–300K) under 0.5T magnetic fields. Weak antiferromagnetic interactions with J =−0.81 and −0.73cm−1 are found for 1 and 2, respectively, showing a very weak coupling, as expected from the diamagnetic long chain –NC–Co–CN–CN– and –NC–Fe–CN–CN– bridges revealed from the single crystal X-ray diffraction studies. [Copyright &y& Elsevier]

Abstract: A new end-to-end (EE) doubly azido bridged dinuclear complex [Cu2L2(μ1,3-N3)2] (1) [where L=(E)-4-(2-(dimethylamino)ethylimino)-1,1,1-trifluoropentan-2-one)] has been synthesized and characterized by elemental and spectroscopic techniques. Single crystal X-ray diffraction analysis reveals that the dimeric complex possesses a center of inversion. Each copper atom in 1 is in a distorted square pyramidal geometry with a CuN4O chromophore as revealed from the τ value, 0.19. The four basal positions are occupied by two imine N and one keto O atom of the Schiff base and one N atom from the azide anion. Another N atom from a coordinated azide occupies the apical position. Temperature dependent magnetic susceptibility of 1 was fitted using the Bleaney–Bowers expression which led to the parameters J =13.6cm−1 and R =3.4×10−5. It indicates a ferromagnetic interaction through the double azido bridges connecting the individual copper Schiff base units. [Copyright &y& Elsevier]

Abstract: The synthesis, crystal structures and magnetic properties of two different copper(II) complexes of formula [Cu(L1)(dca)] n · nClO4 (1) and [Cu(L2)]2(dca)(ClO4) (2) [L1 = N,N-dimethylethylene-N′-(pyridine-2-carbaldiiminato), HL2 = N,N-dimethylethylene-N′-salicylaldiiminato, dca=dicyanamide anion] are described. Spectroscopic and electrochemical properties have also been discussed. A one-dimensional chain structure with single, symmetrical, μ1,5-dca bridges is found in compound 1. The copper atom in 1 has a square pyramidal geometry. A tridentate Schiff base ligand, having NNN donor sites, and one nitrogen atom from dca occupy the basal plane. N(18) of a neighbouring unit occupies the apical site. The Schiff base used in compound 2 is a tridentate anion with NNO donor sites, which changes the structure in a dinuclear unit of copper atoms bridged by single end-to-end dicyanamide ion. The environment around copper in 2 is square planar. Magnetic susceptibility measurements for 1 and 2 reveal the occurrence of weak antiferromagnetic interaction through the dca ligand. [Copyright &y& Elsevier]

Abstract: A 3-D porous coordination polymer of Cu(II) has been synthesized using two different organic bridging ligands, pyridine-2,4-dicarboxylate (pydc) and trans-1,2-bis(4-pyridyl)ethylene (bpe). Here, pydc and bpe connect two adjacent Cu(II) centers, resulting in a rectangular grid-like 2-D sheet with grid dimensions 10.058×15.258 Å. The channels are formed when 2-D networks running along the b-axis which are filled by solvent water molecules. The stability of porous networks, after removal of guest water molecules is confirmed by thermogravimetric analysis and X-ray powder diffraction technique. The low temperature magnetic study has been carried out, which indicates the presence of weak antiferromagnetic coupling with J =−0.59 cm−1. [Copyright &y& Elsevier]

The complex [Cu2(bpc)2(N3)4Ca(H2O)2Na2(H2O)2]n (1) (bpc2−=2,2′-bipyridyl-3,3′-dicarboxylate) has been prepared and characterised by elemental analyses, spectroscopic and single crystal X-ray diffraction study. Single crystal X-ray analysis revealed a novel polynuclear complex containing three different metal centres such as an alkali metal (sodium), an alkaline earth metal (calcium) and a transition metal atom (copper) connected together by azide and carboxylato groups. [Copyright &y& Elsevier]