Search

Blue prismatic crystals of mononuclear [Cu II (O 2 CH) 2 (Py) 3 ] (Py = pyridine, C 5 H 5 N), 1 , were prepared from reaction solution containing dry pyridine and dinuclear [Cu 2 II (O 2 CH) 4 (Py) 2 ]. When a portion of solution together with crystals was exposed to air moisture, crystals of 1 dissolved in mother liquid. Simultaneously, blue needles of 2 , i.e. covalently linked one-dimensional chain structure with formula [Cu(O 2 CH) 2 (Py) 2 ] n · n H 2 O, grew out of the solution. The process lasted few minutes and was observed under optical microscope. The conversion from 1 to 2 takes place also outside of solution in the solid state. Single crystal X-ray diffraction data were collected at 150 K for 1 and after that for 2 , originating from the same reaction solution. This paper reports the structures of both compounds. Alternative synthesis method of 2 arising from a mixture of copper methanoate and pyridine is also reported.

The synthesis and characterization of two polymorphic modifications of new cobalt coordination compound with 2-aminopyridine are reported. The modifications were prepared by the reaction of a solution of cobalt acetate tetrahydrate and 2-aminopyridine. The crystal structures of both polymorphic modifications have been determined by single-crystal X-ray diffraction analysis. The structures of both modifications are quite similar. In both of them the Co2+ is six coordinated by four O atoms from two bidentate chelate acetate ligands and by two N atoms from two 2-aminopyridine molecules. Acetate and 2-aminopyridine ligands are lying cis about the metal centre. The most important difference is in asymmetry of acetate ligand chelate bonding and in H-bonding network. Compounds exhibit an extensive system of intra and intermolecular hydrogen bonding. Magnetic properties of both modifications were studied between 2 K and 300 K giving the result μeff = 4.6 BM for modification I and μeff = 4.7 BM for modification II in paramagnetic region.

We studied the mechanochemical synthesis of KNbO3, starting from a powder mixture of K2CO3 and Nb2O5. The milling experiments were designed with different ball-impact energies in order to investigate the mechanochemical reactions. X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, Raman spectroscopy and transmission electron microscopy were used to characterize the samples. Based on the results, we propose a mechanism for the mechanochemical reaction between K2CO3 and Nb2O5. The first stage of the reaction is characterized by the formation of an amorphous carbonato complex, which decomposes after prolonged milling at higher ball-impact energy giving rise to the crystallization of KNbO3 and other niobate phases with a molar ratio K/Nb

Several new copper(II) complexes with guaiacyl lignin models vanillin (HL1) [Cu(L1)2(nia)2] (1) (nia = nicotinamide) or vanillic acid (HL2) [Cu(L2)2(nia)2] (2) [Cu2(μ-L2)4(nia)2] (3), and [Cu(L2)2(Hetam)2] (4) (Hetam = ethanolamine) were isolated and characterized. The molecular structure of complex 1 reveals bidentate vanillin (HL1) coordination via the methoxy and the deprotonated hydroxy groups. On the other hand, the vanillic acid (HL2) complexes 2 - 4 show a deprotonated carboxylate group with chelating coordination mode in 2, bridging in 3 and monodentate coordination in 4. The mononuclear complexes 1, 2 and 4 show a distorted trans octahedral coordination sphere with pairs of monodentate and chelating ligands. A replacement of the monodentate nicotinamide ligand in 2 with the bidentate ethanolamine ligand in 4 changes the coordination mode of the vanillic acid anion from bidentate (complex 2) to monodentate (complex 4). This shift inside the coordination sphere reveals different O-Cu-O Jahn-Teller axes by the vanillic acid anion in 2 and ethanolamine in 4. Empty channels are present in the crystal structure of the dinuclear complex 3, stabilized by hydrogen bonds and π-π stacking.

A novel dinuclear complex [Cu2(μ-L)4(HL)2] (1) was isolated from starting 2-pyridone (HL) via a resonance and a tautomeric transformation. Each copper centre is in a square-pyramidal coordination sphere, defined by two oxygen atoms (Cu–O4 1.978(5), Cu–O11 1.964(4) A) and two nitrogen atoms (Cu–N2 2.003(5), Cu–N3 2.007(5) A) of four bridging deprotonated pyridin-2-olates and an oxygen atom on the top from a neutral 2-pyridone (Cu–O2 2.227(5) A), analogous to tetracarboxylate paddle-wheel complexes. Compound 1 was compared with mixed pyridin-2-olato/methanoato analogues [Cu2(μ-HCO2)2(μ-L)2(HL)2] · 2CH3CN (2) and [Cu2(μ-HCO2)2(μ-L)2(HL)2] (2a) (2a is an air stable form obtained from 2 outside mother-liquid). The EPR spectra of air stable 1 and 2a show three signals Hz1, H⊥2 and Hz2, typical for the binuclear systems with spin S = 1, both revealing strong antiferromagnetism 2J = −334 (1) and −324 cm−1 (2a). Interestingly, only for 1 additional H⊥1 signal at 100 mT is noticed (D(1) = 0.293 cm−1

Two novel polynuclear complexes with methanoate anions and 3-hydroxypyridine ligands [Cu(l-HCO 2 ) 2 (3-pyOH)] n (1) and [Cu 2 -(l-HCO 2 ) 2 (l-3-pyOH) 2 (3-pyOH) 2 (HCO 2 ) 2 ] n (2), respectively, were synthesized and characterized. The central copper atom in 1 is sur-rounded by four methanoates and a 3-pyOH molecule, forming a square-pyramidal CuO 3 NO chromophore. All the methanoates arebidentate and serve as bridges between the adjacent copper ions via syn-anti and anti–anti coordination. The basal square coordinationaxes are formed by O(syn), N(3-pyOH) (1.974(2), 2.016(2) A˚) and O(anti), O(anti) (1.945(2), 1.960(2) A˚), while the third O(anti)(2.247(2) A˚) is on the top of the pyramid. A ferromagnetic transition with an exchange constant 2J/k B = 9.2 cm 1 is found for 1 below20 K. This interaction probably takes place through two syn-anti methanoates extended in a chain through the 2D structure. On theother hand, two monoatomic Cu–O–Cu intra-dinuclear asymmetric (1.986(2), 2.415(2) A˚) bridges of two methanoates in[Cu

We have studied the mechanism of the mechanochemical interaction between Na 2 CO 3 and Nb 2 O 5 in the initial stage of milling, before the final crystalline oxide product, i.e., NaNbO 3 , is formed. In order to do this, the milling parameters were chosen to give a relatively low ball-impact energy. In addition, one of the reactants, i.e., Na 2 CO 3 , was milled also individually so that the mechanochemical effect on the separately milled compound could be determined. X-ray diffraction analysis, thermal analysis and infrared spectroscopy were used in order to characterize the samples after different milling times. The mechanochemical treatment of the Na 2 CO 3 –Nb 2 O 5 mixture results in the formation of a carbonato complex, which represents an intermediate stage in the mechanochemical synthesis of NaNbO 3 .

Two copper(II) coordination compounds with vanillic acid C8H8O4 (1), namely [Cu- 2(C8H7O4)(2)(O2CCH3)(2)(CH3OH)(2)] (2) and [Cu-2(C8H7O4)(4)(H2O2)(2)] (3), were synthesized and characterized. Single crystals of 1-3 were obtained and their crystal structures determined. The structure of 2 shows dinuclear cage structure of copper acetate hydrate type, however with two different carboxylates, acetates and vanillic acid anions,. respectively. Both bridging anions are in pairs in trans orientation. Methanol molecules are apically coordinated (Cu-O7 2.160(2) angstrom), fulfilling square-pyramidal coordination sphere around both copper ions. The compound 2 decomposes outside mother-liquid (yielding [Cu-2(C8H7O4)(2)(O2CCH3)(2)(H2O)(2)] (2a)) with the removal of methanol, but without significant change of the dicopper tetracarboxylate cage structure, as noticed by mu(eff) 1.48 BM for 2a. Similar was found also in the X-band EPR spectra with three signals H-z1, H-perpendicular to 2 and H-z2 in the region from 0 to 600 mT. The structure of free vanillic acid 1 is composed of dimeric units of two molecules, connected by two parallel hydrogen bonds between carboxylate group of each other (O1-H(...)O2 2.642(3) angstrom), while the structure of 3 is of [Cu-2(O2CCH3)(4)(H2O)(2)] type. Interestingly, an additional signal in the EPR spectra of 3 is found at 80 mT (H- perpendicular to 1) at 298 and at 116 K, next to three signals H-z1, H-perpendicular to 2 and H-z2.

A series of compounds of formula [{Cu2(OOCCmH2m þ 1)4(urea)}2] ðm ¼ 5–11Þ have been characterized. X-ray structure analysis for the hexanoate compound reveals a new type of tetranuclear dicopper(II) tetracarboxylate, where the central coordination sphere in [{Cu2(OOCC5H11)4(urea)}2] is composed of two dinuclear dicopper tetracarboxylates, connected via two inter-dinuclear Cu–O coordination bonds at a distance 2.222(2) � through the apical positions of two dimers. Urea molecules (Cu–O 2.114(2) � occupy both outside apical positions of the resulting tetranuclear units. A strong antiferromagnetic behaviour has been shown for [{Cu2(OOCC5H11)4(urea)}2 ]( � 2J ¼ 261:4ð4Þ cm � 1 ), and compared with related isolated dinuclear and polymeric hexanoate compounds [Cu2(OOCC5H11)4(urea)2], [Cu2(OOCC5H11)4]n, respectively. Only small differences in the magnetic susceptibility have been found, while EPR spectroscopy showed significantly different results for all three hexanoate compounds, also with the dicopper tetracarboxylate central core and square-pyramidal CuO4O chromophores. A solid-to-solid phase transition for [{Cu2 (OOCC5H11)4(urea)}2] was observed by magnetic measurement and analysed for the whole series [{Cu2(OOCCmH2m þ 1)4(urea)}2] by TG, DTA, and variable temperature XRD studies. � 2004 Elsevier B.V. All rights reserved.

The crystal structures of two monomeric copper(II) carboxylates with 2-aminopyridine have been determined by X-ray diffraction. The hexanoate complex crystallizes as its acetonitrile solvate [Cu(C6H11O2)2(C5H6N2)2 · CH3CN] in the triclinic space group P-1 with a = 8.1020(6), b = 13.7106(9), c = 13.7673(9) A, α = 113.79(1), β = 103.86(1), and γ = 94.38(4). The heptanoate compound shows an unsolvated structure [Cu(C7H13O2)2(C5H6N2)2] and also crystallizes in the triclinic space group P-1 with the following cell parameters: a = 8.4487(9), b = 12.238(1), c = 13.504(2) A, α = 87.034(9), β = 77.489(9), and γ = 71.41(1)°. Both compounds contain the CuO4N2 chromophore, with ligands arranged around the copper center in a cis mode. 2-Aminopyridine is coordinated through the endocyclic nitrogen atom. The ortho position of the amino group, with respect to the pyridine nitrogen atom, allows the formation of both, intra-and intermolecular hydrogen bonds.

A series of copper(II) carboxylates with 2-aminopyridine was prepared. In all cases typical dinuclear complexes with a paddle-wheel type structure, Cu2X4L2, as well as mononuclear complexes of type CuX2L2 were obtained (X = hexanoate, heptanoate, octanoate or nonanoate, L = 2-aminopyridine). The structures of monoclinic Cu2(O2CC7H15)4(C5H6N2)2, 1, and Cu(O2CC7H15)2(C5H6N2)2, 2, were determined by X-ray diffraction. VIS-absorption spectroscopic and isothermal calorimetric titrations, were employed to investigate the dimer–monomer equilibrium in acetonitrile solutions. The results were analysed on the basis of the mass-action model to obtain the equilibrium constants of monomer formation (KM ≈ 104 L mol−1). The thermodynamic analysis shows that for all studied systems monomer formation is an enthalpy-driven process (ΔHM° ≈ −14 kJ mol−1). The observed exothermic ΔHM° values result most likely from the attractive coordinative interactions between Cu2+ ion and 2-aminopyridine.

Magnetic interactions in a new copper(II) carboxylate complex {Cu 2 (O 2 CH) 4 }{Cu(O 2 CH) 2 (2-methylpyridine) 2 } were studied with the aim of better understanding magneto-structural correlation in a quasi 1-D spin arrangement. The only magnetic ions in the structure (Cu 2+ , S =1/2) form chains of dimer–monomer units. Copper ions in dimers are bridged by four carboxylate groups with an antiferromagnetic exchange coupling J / k B =−320 K. Susceptibility of the monomer copper ions follows Curie 1/ T law down to 20 K. Below 20 K the susceptibility abruptly decreases due to the antiferromagnetic coupling between monomers.

Complexes of copper(II) octanoate, nonanoate and decanoate with 2-aminoethanol (ethanolamine) have been synthesized and characterized. The crystal structure of Cu(O2CC8H17)2(NH2C2H4OH)2 consists of mononuclear units with pairs of amino nitrogen atoms and deprotonated nonanoato oxygen atoms forming a square coordination plane around the central copper. The hydroxyl oxygen atoms from the 2-aminoethanol ligands are positioned axially with respect to the coordination plane. Results of screening for fungicidal activity against the wood-rotting fungus Trametes versicolor (L. ex Fr.) Pilat show that the complexes totally inhibit fungal growth at a concentration of 1.0 × 10−3 mol/1 but only partially at a concentration of 5.0 × 10−4 mol/1.

The novel title polymeric copper(II) complex, {Na2[Cu3-(CHO2)8]}n, consists of sodium cations and infinite anionic chains, in which neutral dinuclear [Cu2(O2CH)4] moieties alternate with dianionic [Cu(O2CH)4]2- units. Both metal-containing moieties are located on crystallographic inversion centers. The syn-syn bridging configuration between the mononuclear and dinuclear components yields a structure that is significantly more dense than the structures previously reported for mononuclear-dinuclear copper(II) carboxylates with syn-anti or anti-anti bridging modes.

In the title compound, [Cu2(CHO 2 ) 2 (C 6 H 4 NO)2(C 5 H 5 NO) 2 ]-1.02CH 3 CN, the dimeric unit is centrosymmetric, with two bidentate pyridin-2-olate and two bidentate formate syn-syn bridges, and two apical 2-pyridone ligands coordinated through the O atoms. The N atom from the apical 2-pyridone ligand is a donor of a hydrogen bond to the O atom of the bridging pyridinolate ligand of the same complex. The coordination polyhedron of the Cu atom is a distorted square pyramid.

Compounds of the composition CuX 2 (NH 3 ) 2 (H 2 O) (X = heptanoate, octanoate, nonanoate, decanoate or dodecanoate) were prepared, analysed and characterized by vibrational and electron paramagnetic resonance (EPR) spectroscopy and by magnetic susceptibility measurements. The crystal and molecular structure of diammineaquabis(decanoato)copper(II) was determined by X-ray diffraction. The structure consists of mononuclear units with (4 + 2) coordination around central copper.

Mononuclear compounds of the composition CuX2(py)2(H2O) and binuclear of the composition Cu2X4(py)2 (py = pyridine, X = heptanoate, octanoate, nonanoate, decanoate or dedecanoate) were prepared, analysed and characterized by vibrational spectroscopy and thermogravimetry. Generally, the complexes are unstable, the mononuclear being even less stable than binuclear, losing pyridine in air at room temperature. The X-ray crystal structure of the mononuclear adduct of copper(II) nonanoate with pyridine, Cu(O2CC8H17)2(py)2(H2O), was determined by X-ray diffraction. The copper(II) ion is in a square pyramidal environment with two pyridine nitrogen atoms and two oxygen atoms from unidentate nonaoato ligands forming the basal plane of the pyramid and a water molecule coordinated at the apex. The carboxylate oxygen O(2) is not coordinated to copper, but is bound to water from a neighbouring molecule by the OHO(2) hydrogen bond of 2.691 (5) A.

The structure of the title compound, Na2[Cu(CHO2)3.72(C2H3O2)0.28], is built of sodium cations and CuII complex anions; the latter are linked into infinite chains. The CuII atoms are coordinated by five O atoms belonging to five formate ligands, forming a distorted square-pyramidal coordin­ation. Four symmetry-independent formate ligands are bonded to the Cu atom with Cu—O distances in the range 1.9370 (10)–1.9886 (8) A. The fifth formate ligand, bonded to the CuII atom at a longer distance of 2.2889 (9) A, forms a bridge to the neighbouring copper(II) ion which is symmetry-related to the original ion by a twofold screw axis. Thus, infinite chains are formed along the b axis. One of the terminal formate ligands is disordered; 28.4 (13)% of its sites are occupied by acetate, which was present in the starting material and was not completely displaced in the course of the reaction.

Since the first laboratory experiments of M. Carey Lea and the original definition by F. W. Ostwald at the end of the 19th century, mechanochemistry, a field treating chemical changes induced in substances as a result of applied mechanical stress, has been evolved as an important area of chemistry from the viewpoint of both the fundamental research and applications (Takacs, 2004; Boldyrev & Tkacova, 2000). Whereas the fundamentals of mechanochemistry are still being extensively explored, the mechanical alloying, a powder metallurgy process involving ball milling of particles under high-energy impact conditions, met the commercial ground as early as in 1966 and was used to produce improved nickeland iron-based alloys for aerospace industry (Suryanarayana et al., 2001). In addition to metallurgy, the science and technology of mechanochemical processes are continuously developing within various other fields, including ceramics processing, processing of minerals, catalysis, pharmaceutics, and many others.

The crystal structure of the adduct of copper(II) octanoate with pyridine, (Cu2(C7H15COO)4(C5H5N)2, has been determined by X-ray diffraction. The complex forms discrete centrosymmetric tetracarboxylate-bridged dimers with pyridine moieties in the apical positions.

Crystal data: (I) Methylammonium hexachloromolybdate(III) Chloride, (CH3NH3)4[MoCl6]Cl, Mr = 472.38, orthorhombic, Pbam; a = 12.596(3), b = 9.923(2), c = 7.333(2) Å, V = 916.6(7) Å3, T = 293(2) K, Dx = 1.711(1) g cm−3, Dm = 1.70(2) g cm−3, Z = 2, F(000) = 474, MoKα radiation, λ = 0.71069 Å, μ = 17.16 g cm−1, final R = 0.043 and Rw = 0.048 for 1325 observed reflections [I > 3 σ (I)]. (II) Dimethylammonium hexachloromolybdate(III) chloride, [(CH3)2NH2]4[MoCl6]Cl, Mr = 528.48, orthorhombic, P21212; a = 12.867(2), b = 10.158(2), c = 8.719(2) Å, V = 1145.3(7) Å3, T = 293(2) K, Dx = 1.532(1) g cm−3, Dm = 1.53(2) g cm−3, Z = 2, F(000) = 538, MoKα radiation, λ = 0.71069 Å, μ = 13.81 cm−1, final R = 0.019 and Rw = 0.020 for 1548 observed reflections [I > 3 σ (I)]. There exist alternate layers of [Cation/[MoCl6]3−] and [Cation/Cl−] parallel to the (a, b) plane in both structures interlinked by hydrogen bonds N–H…Cl. The space group of compound (II) is a subgroup of the space group of compound (I). The symmetry reduction (Pbam → P21212) results from the orientation of the [Me2NH2]+ ions in compound (II).

Several copper(II) methanoato complexes, namely mononuclear [Cu(O2CH)(2)(2-mpy)(2)] (1) (2-mpy = 2- methylpyridine), binuclear [Cu-2(mu-O2CH)(4)(2-mpy)(2)] (2), and the polynuclear {[Cu(mu-O2CH)(2)(2-mpy)(2)] [Cu-2(mu- O2CH)(4)]}(n) (3) and {Na-2[Cu(mu-O2CH)(2)(O2CH)(2)][Cu-2(mu-O2CH)(4)]}(n) (4), have been synthesized. The mononuclear complex I is formed by two asymmetric chelate methanoate anions and two 2-methylpyridine molecules, giving a highly distorted 'elongated octahedral' coordination sphere. Complex I decomposes outside the mother-liquid, transforming into a regular isolated binuclear paddle-wheel complex 2 with four intra-binuclear bridging methanoates and two axial 2-mpy ligands. The polynuclear complex 3 is formed of alternate mononuclear and binuclear building blocks resembling the central cores of I and 2, but with significant differences, especially for the methanoates of the mononuclear units. The oxygen atom of the mononuclear unit in the octahedral axial position in 3 is simultaneously coordinated to the axial position of the binuclear paddle-wheel central core, thus enabling a chain type of structure. A chain of alternate mononuclear and binuclear building blocks, as in the neutral compound 3. are found as well in the ionic polymeric compound 4, though two types of bridges are found in 4, while there is only one type in 3. Namely, the axial position of the octahedral mononuclear unit in 4 is occupied by the methanoate oxygen atom that is already a part of the binuclear paddle-wheel unit, while one equatorial methanoate from the mononuclear unit serves as a triatomic bridge to the axial position of the binuclear building block. A very strong antiferromagnetic interaction is found for all the complexes with the paddle-wheel building blocks [Cu-2(mu-O2CH)(4)] 2-4 (-2J = 444-482 cm(-1)), attributed to the methanoate intra-binuclear bridges. On the other hand, this strong antiferromagnetism, found already at room temperature, reduces the intensity of the EPR S = 1 spin signals reported for the isolated paddle-wheel complex 2. For the polymeric 3, only the spin S = 1/2 signals are found in the EPR spectra, and they are assigned to the mononuclear building blocks. No signals with a clear origin are however seen in the room temperature EPR spectrum of the polymeric analogue 4, only the S = 1/2 signals in the low temperature spectra. This feature is suggested to be due to a specific influence between the adjacent S = 1 (binuclear) and S = 1/2 (mononuclear) species via their bridges.

In the title compound, [Cu(C 2 H 3 O 2 ) 2 (C 6 H 8 N 2 ) 2 ], the Cu atom is surrounded by two O atoms from the two mono-dentate acetate ligands and by two pyridine N atoms from the two 2-amino-6-methylpyridine ligands in a trans square-planar arrangement. The Cu-O and Cu-N distances are 1.952(2) and 2.046 (2) A, respectively. The complex has an inversion centre. The remaining carboxylate O atoms are located at 2.764 (3) A from the Cu atom, above and below this plane. The coordination around the Cu atom can therefore be described as (4+2). The pyridine ring is twisted 73.2 (1)° with respect to the plane formed by the Cu, the N and the more strongly bonded O atoms.

The Cu II atom in [Cu(C 7 H 5 O 3 ) 2 (C 6 H 6 N 2 O)2(H 2 O)) 2 is octahedrally coordinated by N atoms from two nicotinamide ligands [at 2.018(2) and 2.019 (2) A], by O atoms of two salicylate ligands [at 1.9656(19) and 1.9762(19) A], and by trans water molecules at considerably different distances [2.373 (3) and 2.894 (4) A]. Neutral monomeric units are held together by hydrogen bonds through water molecules and N and O atoms of the CONH 2 group of nicotinamide and carboxylate groups.

The sulfate anion acts as a bridging ligand between the copper(II) ions in the linear polymeric chain of the title compound, [Cu(SO 4 )(C 6 H 6 N 2 O) 2 (H 2 O) 2 ] n . Distorted octahedral coordination about the copper(II) ion is achieved by two ring N atoms of the nicotinamide groups, in a cis conformation [Cu-N 2.016 (3) and 2.018(3)A], by two water molecules [Cu-OW 1.986 (3) and 1.989(3)A], and by two O atoms of two sulfate ligands [Cu-O 2.418 (3) and 2.421 (3) A].

The monoclinic form of the title compound, [Cu(C 7 H 5 O 3 ) 2 (C 6 H 6 N 2 O) 2 ], was isolated during the systematic synthesis of copper salicylates. A distorted octahedral coordination around Cu II , located on the centre of symmetry, is formed by four carboxylic O atoms from two salicylate ligands [Cu-O 1.928 (2) and 2.766 (2) A] and by two N atoms from two nicotinamide groups [Cu-N 2.022 (2) A]. Monomeric structural units are linked together via hydrogen bonds of the type N-H...O between the N and O atoms of the nicotinamide ligands.

Copper(II) acetate [Cu(OOCCH3)2(L1)2] (L1 = 2,6-diaminopyridine) (1), [Cu(OOCCH3)2(L2)2] (L2 = 2-amino-6-methylpyridine) (2) and benzoate compounds [Cu2(OOCC6H5)4(L1)2]·2CH3CN (3), [Cu2(OOCC6H5)4(L1)2] (4), [Cu2(OOCC6H5)4(L2)2] (5), [Cu(OOCC6H5)2(L2)2] (6), were synthesized and characterized. X-ray structure analysis revealed monomeric structure in 1 and 6. In 1, cis arrangement of the ligands was found, and trans in 6, in an elongated octahedral CuO4N2 chromophore. The basal plane in 1 and 6 is formed by one co-ordinated oxygen atom from both carboxylates (Cu–O 1.9560(12)–2.007(3) Å) and pyridine nitrogen atom from two pyridine ligands (Cu–N 2.013(3)–2.282(14) Å), forming a CuO2N2 plane, while the second carboxylate oxygen atoms are more distant (Cu–O 2.488(3)–2.7648(16) Å). The dinuclear paddle- wheel central core was found in 5 (Cu–O 1.942(6)–1.992(6) Å), with pyridine nitrogen atoms in the axial positions (Cu–N 2.283(7), 2.284(7) Å). All compounds were characterized by magnetic measurements, electronic and vibrational spectroscopy and tested for fungal growth retardation activity.

The central CuIIatom of the molecular title complex, [CuCl2(C2H3N3)4], is situated on a site with symmetry 2.22. It is six-coordinated in an elongated octahedral geometry, with the equatorial plane defined by four N atoms of four 1,2,4-triazole ligands and the axial positions occupied by two Cl atoms situated on a twofold axis. The molecules are connectedviaN—H...Cl hydrogen bonds and the crystal consists of two interpenetrating three-dimensional hydrogen-bonded frameworks.

The title compounds, tetrakis(micro-benzoato-O:O')bis(2,6-diaminopyridine)-1kappaN,2kappaN-dicopper(II)-acetonitrile (1/2), [Cu(2)(C(7)H(5)O(2))(4)(C(5)H(7)N(3))(2)].2C(2)H(3)N, (I), and bis(acetonitrile)-1kappaN,2kappaN-tetrakis(micro-benzoato-O:O')dicopper(II)-acetonitrile (1/1.5), [Cu(2)(C(7)H(5)O(2))(4)(C(2)H(3)N)(2)].1.5C(2)H(3)N, (II), crystallize as acetonitrile solvates exhibiting different stability. They have similar molecular structures with discrete dimeric units located at crystallographic inversion centres. The copper ions are bridged by four benzoate groups and neutral N-donor ligands, viz. 2,6-diaminopyridine in (I) and acetonitrile in (II), are coordinated at apical positions. The diverse stability is probably due to hydrogen-bond interactions of the solvated acetonitrile molecules with neighbouring dimers in compound (I).

The structure of the title compound, Na2[Zn(C6H11O2)4], consists of two-dimensional polymeric sheets. The Zn2+ ions are approximately tetrahedrally coordinated by O atoms from different hexanoate anions. Both Na+ ions are six-coordinated by carboxyl­ate O atoms. One of the hexanoate O atoms is attached to one Zn2+ ion and one Na+ ion, and the remaining O atom is attached to two Na+ ions.