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The study investigated the leaching kinetics of Chevreul's salt in ammonium chloride solutions by mechanical agitation experimental system. Reaction temperature, the concentration of ammonium chloride, stirring speed, and the solid-liquid ratio were selected as parameters. Experimental results were correlated using linear regression implemented in the statistical package program. The effect of parameters on Chevreul salt solubility was examined, and integrated rate expression of dissolution rate was found using kinetic models in solid-liquid heterogeneous reactions. The results revealed that the dissolution rate of Chevreul's salt decreased. At the same time, reaction temperature, concentration of ammonium chloride and stirring speed increased while dissolution rate decreased with the increase of the solid-liquid ratio. Based on the result of the applications of the obtained experimental results to the kinetic models, we can deduce that Chevreul's salt dissolution rate is controlled by diffusion through the ash (or product) layer. The activation energy of the dissolution reaction was 17.83 kJ/mol. The integrated rate expression, along with the effects of parameters on Chevreul's salt solubility, was found to be as follows: 1 - 3(1-X)2/3 + 2(1-X) = [2,96.1013.(CA)3,08. (S/L)-0,38.(W)1,23 e -9001,2 / T]. t. [ABSTRACT FROM AUTHOR]

Green synthesis of metal oxides as a treatment for bone diseases is still exploring. Herein, MgO and Fe 2 O 3 NPs were prepared from the extract of Hibiscus sabdariffa L. to study their effect on vit D 3 , Ca +2 , and alkaline phosphatase enzyme ALP associated with osteoporosis. Computational chemistry was utilized to gain insight into the possible interactions. These oxides were characterized by X-ray diffraction, SEM, FTIR, and AFM. Results revealed that green synthesis of MgO and Fe 2 O 3 NPs was successful with abundant. MgO NPs were in vitro applied on osteoporosis patients (n = 35) and showed a significant elevation of vit D 3 and Ca +2 (0.0001 > p < 0.001) levels, compared to healthy volunteers (n = 25). Thus, Hibiscus sabdariffa L. is a good candidate to prepare MgO NPs, with a promising enhancing effect on vit D 3 and Ca +2 in osteoporosis. In addition, interactions of Fe 2 O 3 and MgO NPs with ALP were determined by molecular docking study., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

A comprehensive investigation into the green synthesis of metal oxide nanoparticles (NPs) has garnered significant attention due to its commendable reliability, sustainability, and environmentally friendly attributes. Green synthesis methods play a crucial role in mitigating the adverse effects associated with conventional approaches employed for nanostructure preparation. This research endeavors to examine the impact of ginger plant extract-assisted green synthesis of metal oxides NPs on the serum ferritin levels of anemic diabetic patients in vitro, focusing specifically on α-Fe 2 O 3 and ZnO NPs. Sixty diabetic volunteers with anemia (35-50 years) and thirty healthy volunteers were enrolled as controls. The assessment was conducted using the VIDAS Ferritin (FER) assay. Photoluminescence (PL) spectroscopy measurements were performed to elucidate the intrinsic and extrinsic transitions of these NPs, affirming the successful formation of α-structured iron oxide. Density functional theory (DFT) calculations were carried out at the B3LYP/6-311++G(d,2p) level of theory to investigate the geometry optimization and molecular electrostatic potential maps of the NPs. Furthermore, TD-DFT calculations were employed to explore their frontier molecular orbitals and various quantum chemical parameters. The binding affinity and interaction types of ZnO and α-Fe 2 O 3 NPs to the active site of the human H-Chain Ferritin (PDB ID: 2FHA) target were determined with the help of molecular docking. Results unveiled the crystalline structure of ZnO and the α-structure of α-Fe 2 O 3 . Analysis of the frontier molecular orbitals and dipole moment values demonstrated that ZnO (total dipole moment (D) = 5.80 µ) exhibited superior chemical reactivity, biological activity, and stronger molecular interactions with diverse force fields compared to α-Fe 2 O 3 (D = 2.65 µ). Molecular docking of the metal oxides NPs with human H-chain ferritin provided evidence of robust hydrogen bond interactions and metal-acceptor bonds between the metal oxides and the target protein. This finding could have a great impact on using metal oxides NPs-ferritin as a therapeutic protein, however, further studies on their toxicity are required., (© 2024. The Author(s).)

Two new complexes of Co(II) and Zn(II) 2-chlorobenzoate (2-ClBA) with 3-cyanopyridine (CNP) of the general formula [Co(2-ClBA) 2 (CNP) 2 (H 2 O) 2 ] and [Zn(2-ClBA) 2 (CNP) 2 (H 2 O) 2 ] were synthesized. The structures of the complexes were characterized by single crystal XRD and FT-IR and NMR spectroscopy and Mass Spectrometry (MALDI-TOF MS) methods. Mononuclear complexes exhibit octahedral coordination. In addition, Hirshfeld surface analysis was performed to determine non-covalent interactions in crystal packing. The geometry optimization of the molecules was carried out using the LANL2DZ level of theory of the DFT method and the obtained findings were confirmed by comparing with the data obtained from the single crystal X-ray diffraction method. The theoretical and experimental bond angles and lengths are very close to each other. The effectiveness of the complexes against SARS-CoV-2 enzymes was investigated in silico using the molecular docking method, and a binding score of -8.0 kcal/mol on NSP16 of complex 1 as an inhibitor was obtained. To investigate the drug potential of the complexes, their pharmacokinetic and toxicokinetic properties were estimated by ADMET calculations., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 Elsevier B.V. All rights reserved.)

A new zinc(II) complex, [Zn(CB) 2 (INA) 2 ] (where CB is 4-chlorophenylacetate and INA is 4-pyridine carboxamide) was synthesized. The structure of the complex was characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction technique. Besides, the thermal stability of the complex was investigated by TGA/DTA analysis method. Moreover, the optical absorption and the emission features of the complex were examined by using UV-Vis and fluorescence spectrophotometers, respectively. Furthermore, Density Functional Theory (DFT) calculations were carried out to support the experimental results. Accordingly, it was determined that the complex crystallized in a monoclinic system with space group Pc, a = 8.3329 (2) Å, b = 25.6530 (4) Å, c = 13.5048 (3) Å, α = 90°, β = 91.703 (3)° and γ = 90°. The complex consists two crystallographically independent molecules. In each molecule, the Zn II ion adopts a distorted trigonal pyramidal coordination formed by two O atoms from the two 4 chlorophenylacetate ligand and two N atoms of the two 4-pyridine carboxamide ligands. It was observed that the linear absorption spectra of the complex were similar to linear absorption spectra of the semiconductors. In addition, two emission peaks were observed in the fluorescence spectra which could be due to the formation of excimer and the interactions of the benzene and pyridine rings. The energy gap (ΔE gap  = E LUMO - E HOMO ) of the complex has been calculated as 3.712 eV and this value is very close to the experimentally measured value (3.86 eV). Therefore, because of higher fluorescence intensity of emission peak that was observed between 309 and 556 nm wavelength besides other traits, the complex could potentially be used in the blue light OLED application by filtering of the emission peak around 710 nm wavelength. Graphical Abstract It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. The fluorescence measurements showed that these materials are much suitable for application area of the detection of nitroaromatic explosives. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results. It was reported synthesis and spectroscopic, structural and optical characterization of a new complex that is Zn(II) of 4-Chlorophenylacetate with isonicotinamide. The complex characterized by elemental analysis, Single crystal X-ray diffraction and FT-IR Spectroscopy. Thermal stabilities of the complex have also been investigated. The studying of the optical absorption and fluorescence spectra of the prepared complex is very important for the determination of the optical application areas. In addition to the Density Functional Theory (DFT) calculations were carried out to support the experimental results.

In the title centrosymmetric complex, [Mn(C 10 H 11 O 2 ) 2 (C 10 H 14 N 2 O) 2 (H 2 O) 2 ], the Mn II cation is located on an inversion centre. The four O atoms form a slightly distorted square-planar arrangement around the Mn II cation, and the distorted octa-hedral coordination is completed by two pyridine N atoms at distances of 2.3289 (15) Å. The dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 87.73 (16)°, while the benzene and pyridine rings are oriented at a dihedral angle of 43.03 (8)°. In the crystal, the water mol-ecules are involved in both intra-molecular (to the non-coordinating carboxyl-ate O atom) and inter-molecular (to the amide carbonyl O atom) O-H⋯O hydrogen bonds. The latter lead to the formation of layers parallel to (100). These layers are further linked via weak C-H⋯O hydrogen bonds, resulting in a three-dimensional supra-molecular network. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (70.0%), H⋯O/O⋯H (15.5%) and H⋯C/C⋯H (14.0%) inter-actions. One of the ethyl groups of the di-ethyl-nicotinamide ligand is disordered over two sets of sites, with an occupancy ratio of 0.282 (10):0.718 (10).

The asymmetric unit of the title complex, [Cd(C 10 H 11 O 2 ) 2 (C 6 H 6 N 2 O) 2 (H 2 O)], contains one half of the complex mol-ecule, with the Cd II cation and the coordinated water O atom residing on a twofold rotation axis. The Cd II cation is coordinated in a bidentate manner to the carboxyl-ate O atoms of the two symmetry-related 2,4,6-tri-methyl-benzoate (TMB) anions and to the water O atom at distances of 2.297 (2), 2.527 (2) and 2.306 (3) Å to form a distorted penta-gonal arrangement, while the distorted penta-gonal-bipyramidal coordin-ation sphere is completed by the two pyridine N atoms of the two symmetry-related monodentate nicotinamide (NA) ligands at distances of 2.371 (3) Å in the axial positions. In the crystal, mol-ecules are linked via inter-molecular N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds with R 2 2 (12), R 3 3 (8), R 3 3 (14), R (18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are H⋯H (56.9%), H⋯C/C⋯H (21.3%) and H⋯O/O⋯H (19.0%) inter-actions.3 3 (16), R 3 3 (20), R 3 3 (22), R 4 4 (22), R 5 5 (16), R 6 6 (16) and R 6 6 (18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are H⋯H (56.9%), H⋯C/C⋯H (21.3%) and H⋯O/O⋯H (19.0%) inter-actions.

In the crystal of the title complex, [Cu(C 7 H 6 NO 4 S) 2 (C 6 H 6 N 2 O) 2 (H 2 O)], the Cu II cation and the O atom of the coordinated water mol-ecule reside on a twofold rotation axis. The Cu II ion is coordinated by two carboxyl-ate O atoms of the two symmetry-related 4-sulfamoylbenzoate (SB) anions and by two N atoms of the two symmetry-related nicotinamide (NA) mol-ecules at distances of 1.978 (2) and 2.025 (3) Å, respectively, forming a slightly distorted square-planar arrangement. The distorted square-pyramidal coordination environment is completed by the water O atom in the axial position at a distance of 2.147 (4) Å. In the crystal, the mol-ecules are linked via O-H⋯O and N-H⋯O hydrogen bonds with R 2 (18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯O/O⋯H (42.2%), H⋯H (25.7%) and H⋯C/C⋯H (20.0%) inter-actions.2 (8) and R 2 2 (18) ring motifs, forming a three-dimensional architecture. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯O/O⋯H (42.2%), H⋯H (25.7%) and H⋯C/C⋯H (20.0%) inter-actions.

The asymmetric unit of the title complex, [Zn 3 (C 7 H 5 O 2 ) 6 (C 6 H 4 N 2 ) 2 ], contains one half of the complex mol-ecule, i.e. one and a half Zn II cations, three benzoate (Bnz) and one pyridine-3-carbo-nitrile (Cpy) mol-ecule; the Bnz anions act as bidentate ligands through the carboxyl-ate O atoms, while the Cpy ligand acts as a monodentate N(pyridine)-bonding ligand. The complete centrosymmetric trinuclear complex thus comprises a linear array of three Zn II cations. The central Zn II cation shows an octa-hedral coordination and is bridged to each of the terminal Zn II cations by three Bnz anions. By additional coordination of the CPy ligand, the terminal Zn II cations adopt a trigonal-pyramidal coordination environment. In the crystal, the Bnz anions link to the Cpy N atoms via weak C-H⋯N hydrogen bonds, forming a two-dimensional network. C-H⋯π and π-π inter-actions [between the benzene and pyridine rings of adjacent mol-ecules with an inter-centroid distance of 3.850 (4) Å] help to consolidate a three-dimensional architecture. The Hirshfeld surface analysis confirms the role of H-atom contacts in establishing the packing.

The asymmetric unit of the title complex, [Zn(C 10 H 11 O 2 ) 2 (C 6 H 6 N 2 O) 2 (H 2 O)], contains one half of the complex mol-ecule, and the Zn II cation and the water O atom lie on a twofold rotation axis. The Zn II cation is coordinated by two carboxyl-ate O atoms of the two symmetry-related 2,4,6-tri-methyl-benzoate (TMB) anions and by the water O atom at distances of 2.0311 (16) and 2.076 (2) Å to form a slightly distorted trigonal-planar arrangement, while the distorted trigonal-bipyramidal coordination sphere is completed by the two pyridine N atoms of the two symmetry-related monodentate nicotinamide (NA) ligands at distances of 2.2066 (19) Å in the axial positions. In the crystal, mol-ecules are linked via inter-molecular N-H⋯O and O-H⋯O hydrogen bonds with R 2 2 (12), R -axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (58.4%), H⋯C/C⋯H (20.3%) and H⋯O/O⋯H (18.3%) inter-actions.3 3 (10) and R 3 3 (16) ring motifs, forming a double-column structure running along the c -axis direction. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (58.4%), H⋯C/C⋯H (20.3%) and H⋯O/O⋯H (18.3%) inter-actions.

In the title Ni II complex, [Ni(C 10 H 11 O 2 ) 2 (C 6 H 6 N 2 O) 2 (H 2 O) 2 ]·2H 2 O, the divalent Ni ion occupies a crystallographically imposed centre of symmetry and is coordinated by two O atoms from the carboxyl-ate groups of two 2,4,6-tri-methyl-benzoate (TMB) ligands [Ni-O = 2.0438 (12) Å], two N atoms from the pyridyl groups of two isonicotinamide (INA) ligands [Ni-N = 2.1506 (15) Å] and two water mol-ecules [Ni-O = 2.0438 (12) Å] in a slightly distorted octa-hedral geometry. The coordinating water mol-ecules are hydrogen bonded to the non-coordinating carboxyl-ate O atom of the TMB ligand [O⋯O = 2.593 (3) Å], enclosing an S (6) hydrogen-bonding motif. Two solvent water mol-ecules are also present in the formula unit. In the crystal, a network of inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the complexes into a three-dimensional array. Hirshfeld surface analysis indicates that the most important contributions for the crystal packing are from H⋯H (59.8%), O⋯H/H⋯O (20.2%) and C⋯H/H⋯C (13.7%) inter-actions.

The asymmetric unit of the title one-dimensional polymeric compound, {[Co(C 10 H 11 O 2 ) 2 (H 2 O) 3 ]·2H 2 O} n , contains one Co II cation situated on a centre of inversion, one-half of a coordinating water mol-ecule, one 2,4,6-tri-methyl-benzoate (TMB) anion together with one coordinating and one non-coordinating water mol-ecule; the TMB anion acts as a monodentate ligand. In the anion, the carboxyl-ate group is twisted away from the attached benzene ring by 84.9 (2)°. The Co II atom is coordinated by two TMB anions and two water mol-ecules in the basal plane, while another water mol-ecule bridges the Co II atoms in the axial directions, forming polymeric chains running along [001]. The coordination environment for the Co II cation is a slightly distorted octa-hedron. The coordinating and bridging water mol-ecules link to the carboxyl-ate groups via intra- and inter-molecular O-H⋯O hydrogen bonds, enclosing S (6) ring motifs, while the coordinating, bridging and non-coordinating water mol-ecules link to the carboxyl-ate groups and the coordinating water mol-ecules link to the non-coordinating water mol-ecules via O-H⋯O hydrogen bonds, enclosing R 2 (8) ring motifs. Weak C-H⋯O and C-H⋯π inter-actions may further stabilize the crystal structure.2 (8) and R 3 3 (8) ring motifs. Weak C-H⋯O and C-H⋯π inter-actions may further stabilize the crystal structure.

The asymmetric unit of the title compound, [Cd 2 (C 7 H 4 NO 4 ) 4 (C 6 H 4 N 2 ) 4 ], contains one Cd II atom, two 3-nitro-benzoate (NB) anions and two 3-cyano-pyridine (CPy) ligands. The two CPy ligands act as monodentate N(pyridine)-bonding ligands, while the two NB anions act as bidentate ligands through the carboxyl-ate O atoms. The centrosymmetric dinuclear complex is generated by application of inversion symmetry, whereby the Cd II atoms are bridged by the carboxyl-ate O atoms of two symmetry-related NB anions, thus completing the distorted N 2 O 5 penta-gonal-bipyramidal coordination sphere of each Cd II atom. The benzene and pyridine rings are oriented at dihedral angles of 10.02 (7) and 5.76 (9)°, respectively. In the crystal, C-H⋯N hydrogen bonds link the mol-ecules, enclosing R 2 C-H⋯O hydrogen bonds, resulting in a three-dimensional network. In addition, π-π stacking inter-actions between parallel benzene rings and between parallel pyridine rings of adjacent mol-ecules [shortest centroid-to-centroid distances = 3.885 (1) and 3.712 (1) Å, respectively], as well as a weak C-H⋯π inter-action, may further stabilize the crystal structure.2 (26) ring motifs, in which they are further linked via C-H⋯O hydrogen bonds, resulting in a three-dimensional network. In addition, π-π stacking inter-actions between parallel benzene rings and between parallel pyridine rings of adjacent mol-ecules [shortest centroid-to-centroid distances = 3.885 (1) and 3.712 (1) Å, respectively], as well as a weak C-H⋯π inter-action, may further stabilize the crystal structure.

The mononuclear title cadmium complex, [Cd(C 10 H 14 N 2 O) 2 (C 8 H 4 NO 2 ) 2 (H 2 O) 2 ], is centrosymmetric and contains two water mol-ecules, two 4-cyanobenzoate (CB) ligands and two di-ethyl-nicotinamide (DENA) ligands. All the ligands are coordinated to the Cd II atom in a monodentate mode. The four nearest O atoms around the Cd II atom form a slightly distorted square-planar arrangement, with the distorted octa-hedral coordination sphere being completed by the two pyridine N atoms of the DENA ligands at distances of 2.3336 (13) Å. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 8.75 (16)°, while the benzene and pyridine rings are oriented at a dihedral angle of 57.83 (5)°. The water mol-ecules exhibit both intra-molecular [to the non-coordinating carboxyl-ate O atom, enclosing an S (6) hydrogen-bonding motif, where O⋯O = 2.670 (2) Å] and inter-molecular [to the amide carbonyl O atom, enclosing an R (16) ring motif, where O⋯O = 2.781 (2) Å] O-H⋯O hydrogen bonds. The latter lead to the formation of supra-molecular chains propagating along [110].2 2 (16) ring motif, where O⋯O = 2.781 (2) Å] O-H⋯O hydrogen bonds. The latter lead to the formation of supra-molecular chains propagating along [110].

In the title complex, [Zn(C 8 H 4 NO 2 ) 2 (C 10 H 14 N 2 O) 2 (H 2 O) 2 ], the Zn II cation, located on an inversion centre, is coordinated by two water mol-ecules, two 4-cyano-benzoate (CB) anions and two di-ethyl-nicotinamide (DENA) ligands in a distorted N 2 O 4 octa-hedral geometry. In the mol-ecule, the dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 9.50 (14)°, while the benzene and pyridine rings are oriented at a dihedral angle of 56.99 (5)°. The water mol-ecules exhibit both an intra-molecular hydrogen bond [to the non-coordinating carboxyl-ate O atom, enclosing an S (6) hydrogen-bonding motif, where O⋯O = 2.6419 (19) Å] and an inter-molecular hydrogen bond [to the amide carbonyl O atom, enclosing an R 2 2 (16) ring motif, where O⋯O = 2.827 (2) Å]; the latter lead to the formation of supra-molecular chains propagating along the [110] direction.

The asymmetric unit of the title polymeric compound, [Cu(C8H4NO2)2(C10H14N2O)(H2O)] n , contains one Cu(II) atom, one coordinating water mol-ecule, two 4-cyano-benzoate (CB) ligands and one coordinating N,N-di-ethyl-nicotinamide (DENA) mol-ecule. The DENA ligand acts as a bis-monodentate ligand, while the CB anions are monodentate. Two O atoms of the CB ligands, one O atom of the water mol-ecule and the pyridine N atom of the DENA ligand form a slightly distorted square-planar arrangement around the Cu(II) atom which is completed to a square-pyramidal coordination by the apically placed O atom of the DENA ligand, with a Cu-O distance of 2.4303 (15) Å. In the two CB anions, the carboxyl-ate groups are twisted relative to the attached benzene rings by 2.19 (12) and 3.87 (15)°, while the benzene rings are oriented at a dihedral angle of 5.52 (8)°. The DENA ligands bridge adjacent Cu(2+) ions, forming polymeric coordination chains running along the b axis. In the crystal, strong water-carboxyl-ate O-H⋯O hydrogen bonds link adjacent chains into layers parallel to (10-1) and weak C-H⋯O hydrogen bonds further stabilize the crystal structure. The cyano group C and N atoms of one of the CB ligands are disordered over two sets of sites with equal occupancies.

The asymmetric unit of the mononuclear cobalt complex, [Co(C11H13O2)2(C6H6N2O)2(H2O)2]·2H2O, contains one half of the complex mol-ecule, one coordinating and one non-coordinating water mol-ecule, one 4-tert-butyl-benzoate (TBB) ligand and one nicotinamide (NA) ligand; the Co atom lies on an inversion centre. All ligands coordinating to the Co atom are monodentate. The four nearest O atoms around the Co atom form a slightly distorted square-planar arrangement, with the distorted octa-hedral coordination completed by the two pyridine N atoms of the NA ligands at distances of 2.1638 (11) Å. The coordinating water mol-ecules are hydrogen bonded to the carboxyl O atoms [O ⋯ O = 2.6230 (17) Å], enclosing an S(6) hydrogen-bonding motif, while inter-molecular O-H⋯O hydrogen bonds link two of the non-coordinating water mol-ecules to the coordinating water mol-ecules and NA anions. The dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 29.09 (10)°, while the benzene and pyridine rings are oriented at a dihedral angle of 88.53 (4)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, enclosing R 2 (2)(8), R 2 (2)(10) and R 4 (4)(12) ring motifs, forming layers parallel to (001). The C and H atoms of the tert-butyl group of the TBB ligand are disordered over two sets of sites with an occupancy ratio of 0.631 (5):0.369 (5).

The asymmetric unit of the title compound, [Mn(C7H4NO4)2(C6H6N2O)2(H2O)2], contains one Mn(II) atom, one 4-nitro-benzoate (NB) anion, one nicotinamide (NA) ligand and one water mol-ecule; NA and NB each act as a monodentate ligand. The Mn(II) atom, lying on an inversion centre, is coordinated by four O atoms and two pyridine N atoms in a distorted octa-hedral geometry. The water mol-ecules are hydrogen bonded to the carboxyl-ate O atoms. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 24.4 (3)°, while the benzene and pyridine rings are oriented at a dihedral angle of 86.63 (11)°. In the crystal, O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules, forming a layer parallel to the ab plane. The layers are further linked via weak C-H⋯O hydrogen bonds, a π-π stacking inter-action [centroid-centroid distance = 3.868 (2) Å] and a weak C-H⋯π inter-action, resulting in a three-dimensional network.

The centrosymmetric mol-ecule in the monomeric title cobalt complex, [Co(C10H11O2)2(C10H14N2O)2(H2O)2], contains two water mol-ecules, two 2,4,6-tri-methyl-benzoate (TMB) ligands and two di-ethyl-nicotinamide (DENA) ligands. All ligands coordinate to the Co(II) atom in a monodentate fashion. The four O atoms around the Co(II) atom form a slightly distorted square-planar arrangement, with the distorted octa-hedral coordination sphere completed by two pyridine N atoms of the DENA ligands. The dihedral angle between the planar carboxyl-ate group and the adjacent benzene ring is 84.2 (4)°, while the benzene and pyridine rings are oriented at a dihedral angle of 38.87 (10)°. The water mol-ecules exhibit both intra-molecular (to the non-coordinating carboxyl-ate O atom) and inter-molecular (to the amide carbonyl O atom) O-H⋯O hydrogen bonds. The latter lead to the formation of layers parallel to (100), enclosing R 4 (4)(32) ring motifs. These layers are further linked via weak C-H⋯O hydrogen bonds, resulting in a three-dimensional network. One of the two ethyl groups of the DENA ligand is disordered over two sets of sites with an occupancy ratio of 0.490 (13):0.510 (13).

In the title binuclear Cu(II) complex, [Cu2(C10H11O2)4(C6H6N2O)2], the two Cu(II) cations [Cu⋯Cu = 2.5990 (5) Å] are bridged by four 2,4,6-tri-methyl-benzoate (TMB) anions. The four nearest O atoms around each Cu(II) cation form distorted square-planar arrangements and the distorted square-pyramidal coordinations are completed by the pyridine N atoms of nicotinamide mol-ecules at distances of 2.164 (2) and 2.165 (2) Å, respectively. The Cu(II) cations are displaced by -0.2045 (3) and 0.2029 (3) Å from the corresponding planes formed by the nearest four O atoms. In the mol-ecule, the dihedral angles between the planes of the benzene rings and the adjacent carboxyl-ate groups are 80.6 (2), 51.4 (2), 24.4 (2) and 32.5 (2)°, while the planes of the pyridine rings are oriented at a dihedral angle of 11.28 (10)°. In the crystal, bifurcated N-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules, enclosing R 2 (2)(8) and R 4 (4)(8) ring motifs, into a three-dimensional network. The structure contains a solvent-accessible void of 72 Å(3), but there is no solvent mol-ecule located within this void. The crystal studied was an inversion twin refined with a minor component of 0.488 (8).

The asymmetric unit of the title salt, [Zn(C8H4NO2)(C6H6N2O)(H2O)3](C8H4NO2), contains one complex cation and one 4-cyano-benzoate (CNB) counter-anion. The Zn(II) atom in the cation is coordinated by one 4-cyano-benzoate ligand, one nicotinamide (NA) ligand and three water mol-ecules, the CNB anion thereby coordinating in a bidentate O,O'-mode through the carboxyl-ate group. The latter, together with one water O atom and the N atom of the NA ligand, form a distorted square-planar arrangement, while the considerably distorted octa-hedral coordination sphere of the Zn(II) atom is completed by the two O atoms of additional water mol-ecules in the axial positions. The dihedral angles between the planar carboxyl-ate groups and the adjacent benzene rings in the two anions are 10.25 (10) and 5.89 (14)°. Inter-molecular O-H⋯O hydrogen bonds link two of the coordinating water mol-ecules to two free CNB anions. In the crystal, further hydrogen-bonding inter-actions are present, namely N-H⋯O, O-H⋯O and C-H⋯O hydrogen bonds that link the mol-ecular components, enclosing R 2 (2)(12), R 3 (3)(8) and R 3 (3)(9) ring motifs and forming layers parallel to (001). π-π contacts between benzene rings [centroid-to-centroid distances = 3.791 (1) and 3.882 (1) Å] may further stabilize the crystal structure.

In the title complex, [Co(C8H4NO2)2(C6H6N2O)2(H2O)2], the Co(II) atom is located on an inversion centre and is coordinated by two 4-cyano-benzoate (CNB) anions, two nicotinamide (NA) ligands and two water mol-ecules. The four O atoms in the equatorial plane form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination sphere is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 22.11 (15)°, while the pyridine and benzene rings are oriented at a dihedral angle of 89.98 (5)°. In the crystal, inter-molecular N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules, enclosing R 2 (2)(8) and R 4 (4)(8) ring motifs, forming layers parallel to (100). The layers are linked via C-H⋯O and C-H⋯N hydrogen bonds, resulting in a three-dimensional network. A weak C-H⋯π inter-action is also observed.

The asymmetric unit of the title coordination polymer, [Zn(C7H4NO4)2(C6H6N2O)2] n , contains two 4-nitro-benzoate (NB) anions and two nicotinamide (NA) ligands. The Zn(II) atom has a slightly distorted octa-hedral coordination sphere. In the equatorial plane, it is coordinated by three carboxyl-ate O atoms of the NB anions and one O atom of one of the two NA ligands. The axial positions are occupied by the pyridine N atoms of the two NA ligands. In the two NB anions, the carboxyl-ate groups are twisted away from the attached benzene rings by 13.8 (2) and 13.4 (2)°, while the benzene rings are oriented at a dihedral angle of 11.5 (2)°. The dihedral angle between the NA rings is 10.3 (1)°. Only one of the two NB anions and one of the two NA ligands bridge adjacent Zn(II) ions through eight- and twelve-membered rings, respectively, forming polymeric chains running along the a-axis direction. In the crystal, N-H ⋯ O hydrogen bonds link adjacent chains, enclosing R(16), R 2 (2)(20) and R 6 (6)(16) ring motifs, forming layers parallel to (01-1). The layers are linked via a number of C-H⋯O hydrogen bonds, forming a three-dimensional network.

The asymmetric unit of the title polymeric compound, [Zn(C8H5O3)2(C4H4N2)(H2O)] n , contains two mol-ecular units. Each unit comprises two 4-formyl-benzoate (FB) anions, one pyrazine mol-ecule and one coordinating water mol-ecule; the FB anions act either as bidentate or as monodentate ligands. The O atoms of the bidentately coordinating FB anions are disordered over two positions, and they were refined with fixed occupancy ratios of 0.75:0.25 and 0.70:0.30, respectively. In the ordered monodentately coordinating FB anions, the carboxyl-ate groups are twisted away from the attached benzene rings (B and E) by 12.1 (2) and 9.2 (2)°, respectively. In the disordered FB anions, the corresponding angles are 14.1 (1) and 4.0 (2)° for benzene rings A and D, respectively. Benzene rings A and B are oriented at a dihedral angle of 45.7 (1)°, D and E at 23.2 (1)°. Pyrazine ring C makes dihedral angles of 85.6 (1) and 72.7 (1)°, respectively, with benzene rings A and B, and pyrazine ring F makes dihedral angles of 87.0 (1) and 81.3 (1)° with benzene rings D and E, respectively. The pyrazine ligands bridge the Zn(II) cations, forming polymeric chains running parallel to the b-axis direction. Medium-strength intra-molecular O-H⋯O hydrogen bonds link the water mol-ecules to the carboxyl-ate O atoms. In the crystal, water-carboxyl-ate O-H⋯O hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via weak pyrazine-formyl C-H⋯O and form-yl-carboxyl-ate C-H⋯O hydrogen bonds. π-π contacts between the benzene rings, with centroid-to-centroid distances of 3.7765 (16), 3.7905 (15) and 3.8231 (16) Å, may further stabilize the structure. There are also weak C-H⋯π inter-actions present.

In the title polymeric compound, [Co(C8H5O3)2(C4H4N2)(H2O)2] n , the Co(II) atom is located on a twofold rotation axis and has a slightly distorted octa-hedral coordination sphere. In the equatorial plane, it is coordinated by two carboxyl-ate O atoms of two symmetry-related monodentate formyl-benzoate anions and by two N atoms of two bridging pyrazine ligands. The latter are bis-ected by the twofold rotation axis. The axial positions are occupied by two O atoms of the coordinating water mol-ecules. In the formyl-benzoate anion, the carboxyl-ate group is twisted away from the attached benzene ring by 7.50 (8)°, while the benzene and pyrazine rings are oriented at a dihedral angle of 64.90 (4)°. The pyrazine ligands bridge the Co(II) cations, forming linear chains running along the b-axis direction. Strong intra-molecular O-H⋯O hydrogen bonds link the water mol-ecules to the carboxyl-ate O atoms. In the crystal, weak O-Hwater⋯Owater hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via C-Hpyrazine⋯Oform-yl hydrogen bonds, forming a three-dimensional network. There are also weak C-H⋯π inter-actions present.

In the title polymeric compound, [Ni(C8H5O3)2(C4H4N2)(H2O)2] n , the Ni(II) atom is located on a twofold rotation axis and has a slightly distorted octa-hedral coordination sphere. In the equatorial plane, it is coordinated by two carboxyl-ate O atoms of two symmetry-related monodentate formyl-benzoate anions and by two N atoms of the bridging pyrazine ligand, which is bis-ected by the twofold rotation axis. The axial positions are occupied by two O atoms of the coordinating water mol-ecules. In the formyl-benzoate anion, the carboxyl-ate group is twisted away from the attached benzene ring by 7.0 (6)°, while the benzene and pyrazine rings are oriented at a dihedral angle of 66.2 (3)°. The pyrazine ligands bridge the Ni(II) cations, forming polymeric chains running along the b-axis direction. Intra-molecular O-H⋯O hydrogen bonds link the water ligands to the carboxyl-ate O atoms. In the crystal, water-water O-H⋯O hydrogen bonds link adjacent chains into layers parallel to the bc plane. Pyrazine-formyl C-H⋯O hydrogen bonds link the layers, forming a three-dimensional network. There are also weak C-H⋯π inter-actions present. The title compound is isotypic with the copper(II) complex [Çelik et al. (2014a). Acta Cryst. E70, m4-m5].

The polymeric title compound, [Cd(C8H5O3)2(C4H4N2)(H2O)] n , contains two 4-formyl-benzoate (FB) anions, one pyrazine mol-ecule and one coordinating water mol-ecule; the FB anions act as bidentate ligands. The O atom, the aldehyde H atom and the benzene ring of one of the FB anions are disordered over two positions. The O atoms were freely refined [refined occupancy ratio 0.79 (2):0.21 (2)], while the aldehyde H atoms and the benzene ring atoms were refined with fixed occupancy ratios of 0.8:0.2 and 0.5:0.5, respectively. In the ordered FB anion, the carboxyl-ate group is twisted away from the attached benzene ring (A) by 22.7 (8)°. In the disordered FB anion, the corresponding angles are 15.6 (10) and 11.4 (11)° for rings B and B', respectively. Benzene rings A and B are oriented at a dihedral angle of 24.2 (7), A and B' at 43.0 (8)°. The pyrazine ring makes dihedral angles of 67.5 (4), 89.6 (7) and 86.2 (7)°, respectively, with benzene rings A, B and B'. The pyrazine ligands bridge the Cd(II) cations, forming polymeric chains running along the b-axis direction. In the crystal, O-Hwater ⋯ Ocarboxyl-ate hydrogen bonds link adjacent chains into layers parallel to the bc plane. These layers are linked via C-Hpyrazine ⋯ Oform-yl hydrogen bonds, forming a three-dimensional network. π-π interactions [centroid-centroid distances = 3.870 (11)-3.951 (5) Å] further stabilize the crystal structure. There is also a weak C-H⋯π inter-action present.

In the title polymeric compound, [Cu(C8H5O3)2(C4H4N2)(H2O)2] n , the Cu(II) atom is located on a twofold rotation axis and has a slightly distorted octa-hedral coordination sphere. In the equatorial plane, it is coordinated by two carboxyl-ate O atoms of two symmetry-related monodentate formyl-benzoate anions and by two N atoms of the bridging pyrazine ligand, which is bis-ected by the twofold rotation axis. The axial positions are occupied by two O atoms of the coordinating water mol-ecules. In the formyl-benzoate anion, the carboxyl-ate group is twisted away from the attached benzene ring by 6.2 (2)°, while the benzene and pyrazine rings are oriented at a dihedral angle of 68.91 (8)°. The pyrazine ligands bridge the Cu(II) cations, forming polymeric chains running along the b-axis direction. Strong intra-molecular O-H⋯O hydrogen bonds link the water mol-ecules to the carboxyl-ate O atoms. In the crystal, O-Hwater⋯Owater hydrogen bonds link adjacent chains into layers parallel to the bc plane. The layers are linked via C-Hpyrazine⋯Oform-yl hydrogen bonds, forming a three-dimensional network. There are also weak C-H⋯π inter-actions present.

In the crystal of the title Cd(II) polymeric complex, [Cd(C7H4ClO2)2(C10H14N2O)(H2O)] n , the Cd(II) cation is chelated by two chloro-benzoate anions and coordinated by two N,N-di--ethyl-nicotinamide (DENA) ligands and one water mol-ecule in a distorted NO6 penta-gonal-bipyramidal geometry. The Cd(II) cations are bridged by the pyridine N atom and carbonyl O atom of the DENA ligand to form a polymeric chain running along the b axis. Inter-molecular O-H⋯O hydrogen bonds between coordinating water mol-ecules and carboxyl-ate groups link adjacent chains into layers parallel to the bc plane. π-π contacts between benzene rings [shortest centroid-centroid distance = 3.912 (2) Å] further stabilizes the crystal structure. In the mol-ecule, weak C-H⋯O hydrogen bonds occur between the pyridine ring and carboxyl-ate groups; the dihedral angles between the carboxyl-ate groups and adjacent benzene rings are 4.6 (3) and 12.8 (3)°, while the benzene rings are oriented at a dihedral angle of 1.89 (13)°.

The title compound, [Cu(C7H4ClO2)2(C10H14N2O)2(H2O)], has twofold symmetry with the Cu(II) cation and the O atom of the coordinating water mol-ecule located on the axis. The Cu(II) cation is coordinated by two carboxyl-ate O atoms of chloro-benzoate (CB) anions, two N atoms of N,N-di-ethyl-nicotinamide (DENA) ligands and one water mol-ecule in a distorted N2O3 square-pyramidal geometry. The benzene and pyridine rings are oriented at a dihedral angle of 82.51 (6)°. In the anionic ligand, the carboxyl-ate group is twisted away from the attached benzene ring by 12.85 (11)°. In the crystal, O-H⋯O hydrogen bonds between the coordinating water mol-ecule and the carboxyl group link the complex mol-ecules into supra-molecular chains running along the c-axis direction.

In the title centrosymmetric binuclear Cu(II) complex, [Cu2(C7H4ClO2)4(C10H14N2O)2], the two Cu(II) cations [Cu⋯Cu = 2.6314 (4) Å] are bridged by four 3-chloro-benzoate (CB) anions. The four carboxyl-ate O atoms around each Cu(II) cation form a distorted square-planar arrangement, the distorted square-pyramidal coordination geometry being completed by the pyridine N atom of the N,N-di-ethyl-nicotinamide (DENA) mol-ecule. The dihedral angle between the benzene ring and the carboxyl-ate group is 4.49 (11)° in one of the independent CB ligands and 12.00 (10)° in the other. The benzene rings of the independent CB ligands are oriented at a dihedral angle of 84.13 (6)°. In the crystal, weak C-H⋯O hydrogen bonds link the binuclear complex mol-ecules into supra-molecular chains running along [101].

In the centrosymmetric dinuclear title compound, [Cd2(C7H4ClO2)4(C6H6N2O)2(H2O)2], the Cd(II) atom is coord-inated by one N atom from one bridging nicotinamide ligand and one O atom from another symmetry-related bridging nicotinamide ligand, four O atoms from two 3-chloro-benzoate ligands and one water mol-ecule in an irregular geometry. The dihedral angles between the carboxyl-ate groups and the adjacent benzene rings are 6.98 (12) and 2.42 (13)°, while the benzene rings are oriented at a dihedral angle of 4.33 (6)°. Inter-molecular O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. π-π inter-actions, indicated by short centroid-centroid distances [3.892 (1) Å between the pyridine rings and 3.683 (1) Å between the benzene rings] further stabilize the structure.

In the polymeric title compound, [Zn(C7H4ClO2)2(H2O)] n , the Zn(II) cation is located on a twofold rotation axis and is coordinated by carboxylate O atoms of four monodentate chloro-benzoate anions and by one water mol-ecule, located on a twofold rotation axis, in a distorted square-pyramidal geometry. In the anion, the carboxyl-ate group is twisted away from the attached benzene ring by 44.16 (11)°. The chloro-benzoate anion bridges Zn(II) cations, forming polymeric chains running along the c-axis direction. O-H⋯O hydrogen bonds between coordinating water mol-ecules and carboxyl-ate groups link adjacent chains into layers parallel to the bc plane.

The mol-ecule of the title Cu(II) complex, [Cu(C7H4ClO2)2(C6H6N2O)2], contains two 3-chloro-benzoate (CB) and two nicotinamide (NA) ligands; the CB act as bidentate ligands, while the NA are monodentate ligands. The resulting CuN2O4 coordination polyhedron is a considerably distorted octahedron. The dihedral angles between the carboxyl-ate groups and the adjacent benzene rings are 17.92 (12) and 24.69 (16)°, while the two benzene rings and the two pyridine rings are oriented at dihedral angles of 52.20 (8) and 1.56 (6)°. In the crystal, N-H⋯N and C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. The π-π contact between the benzene rings [centroid-centroid distance = 3.982 (2) Å] may further stabilize the crystal structure.

In the title complex, [Co(C7H4ClO2)2(C6H6N2O)2(H2O)2], the Co(II) atom is located on an inversion center and is coordinated by two 3-chloro-benzoate (CB) anions, two nicotinamide (NA) ligands and two water mol-ecules. The four O atoms in the equatorial plane form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 9.14 (9)°, while the pyridine and benzene rings are oriented at a dihedral angle of 82.18 (8)°. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds link the mol-ecules into a two-dimensional network lying parallel to (101). π-π stacking between parallel pyridine rings of adjacent mol-ecules [centroid-centroid distance = 3.7765 (8) Å] further stabilizes the crystal structure.

The asymmetric unit of the centrosymmetric dinuclear title compound, [Cu2(C8H5O3)4(C6H6N2O)4], contains one half of the complex mol-ecule. The Cu(II) atoms are bridged by the carboxyl-ate groups of two 4-formyl-benzoate (FOB) anions. Besides the two bridging FOB anions, one additional chelating FOB anion and two isonicotinamide (INA) ligands complete the distorted CuN2O4 octa-hedral coordination of each Cu(2+) cation. Within the asymmetric unit, the benzene and pyridine rings are oriented at dihedral angles of 25.1 (3) and 12.6 (3)°, respectively. In the crystal, N-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. π-π contacts between the pyridine rings [shortest centroid-centroid distance = 3.821 (3) Å] may further stabilize the crystal structure. One of the formyl groups of the two FOB anions is disordered over two sets of sites with an occupancy ratio of 0.65:0.35.

The asymmetric unit of the title compound, [Zn(C6H6N2O)2(H2O)4](C7H5O3)2·4H2O, contains half of the complex cation with the Zn(II) ion located on an inversion center, a 3-hy-droxy-benzoate counter-anion and two uncoordinating water mol-ecules. Four water O atoms in the equatorial plane around the Zn(II) ion [Zn-O = 2.089 (2) and 2.128 (2) Å] form a slightly distorted square-planar arrangement and the distorted octa-hedral geometry is completed by the two N atoms [Zn-N = 2.117 (2) Å] from two isonicotinamide ligands. In the anion, the carboxyl-ate group is twisted from the attached benzene ring at 9.0 (2)°. In the crystal, a three-dimensional hydrogen-bonding network, formed by classical O-H⋯O and N-H⋯O and weak C-H⋯O hydrogen bonds, consolidates the crystal packing, which exhibits π-π stacking between the benzene and pyridine rings, with centroid-centroid distances of 3.458 (2) and 3.609 (2) Å. One of the two H atoms of each uncoordinating water mol-ecule is disordered over two orientations with an occupancy ratio of 0.60:0.40.

The crystal structure of the title compound, [Cd(C7H5O3)2(C6H6NO)2(H2O)2]·2[Cd(C7H5O3)2(C6H6NO)(H2O)2]·4H2O, consists of two kinds of Cd(II) complexes (A and B) and lattice water mol-ecules. In complex A, [Cd(C7H5O3)2(C6H6NO)2(H2O)2], the Cd(II) cation is located on an inversion center and is coordinated by two salicylate anions, two nicotinamide (NA) ligands and two water mol-ecules in a slightly distorted octa-hedral geometry. In complex B, [Cd(C7H5O3)2(C6H6NO)(H2O)2], the Cd(II) cation is coordinated by two salicylate anions, one nicotinamide (NA) ligand and two water mol-ecules in an irregular seven-coordinate geometry. There are extensive intra-molecular O-H⋯O and weak C-H⋯O hydrogen bonds as well as extensive inter-molecular O-H⋯O and N-H⋯O hydrogen bonding in the crystal structure. π-π stacking between the pyridine and benzene rings, between the benzene rings, between the benzene and pyridine rings and between the pyridine rings [centroid-centroid distances = 3.5989 (10), 3.6005 (10), 3.5800 (9) and 3.5205 (10) Å, respectively] further stabilize the crystal structure. A weak N-H⋯π inter-action also occurs. One of the lattice water mol-ecules is disordered over two positions with an occupancy ratio of 0.70:0.30.

In the title complex, [Co(C7H4ClO2)2(C6H6N2O)2(H2O)2], the Co(II) cation is located on an inversion center and is coord-inated by two 2-chloro-benzoate anions, two nicotin-amide (NA) ligands and two water mol-ecules. The four O atoms in the equatorial plane around the Co(II) cation form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two pyridine N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 29.7 (4)°, while the pyridine and benzene rings are oriented at a dihedral angle of 83.17 (15)°. Intra-molecular O-H⋯O hydrogen bonding occurs between the carboxyl-ate group and coordinating water mol-ecule. In the crystal, inter-molecular N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

In the dinuclear centrosymmetric title compound, [Cd2(C8H7O2)4(C6H6N2O)2(H2O)2], the Cd(II) ion is chelated by two carboxyl-ate groups from 4-methyl-benzoate anions, and is further coordinated by one nicotinamide and one water mol-ecule; a carboxyl-ate O atom from an adjacent 4-methyl-benzoate anion bridges to the Cd(II) ion, completing the irregular coordination sphere of the seven ligand atoms. In the crystal, inter-molecular O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network. The methyl-benzene moiety of one bridging 4-methyl-benzoate anion is disordered over two orientations of equal occupancy.

In the title complex, [Cu(C(7)H(4)IO(2))(2)(C(6)H(6)N(2)O)(2)(H(2)O)(2)], the Cu(II) cation is located on an inversion center and is coordinated by two monodentate 2-iodo-benzoate (IB) anions, two nicotinamide (NA) ligands and two water mol-ecules in a distorted octa-hedral coordination geometry. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 32.12 (14)°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 82.02 (5)°. The coordinating water mol-ecule links with the carboxyl-ate group via an intra-molecular O-H⋯O hydrogen bond. In the crystal, N-H⋯O, O-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular network.

In the title polymeric compound, [Pb(C(12)H(6)N(2)O(4))](n), the Pb(II) cation, located on a mirror plane, is N,N'-chelated by a 2-2'-bipyridine-5,5'-dicarboxyl-ate (bpdc) anion and is further coordinated by six O atoms from four carboxyl groups of bpdc anions in an irregular N(2)O(6) geometry. The carboxylate groups bridge the Pb(II) cations, forming a three-dimensional polymeric structure. The carboxyl-ate group is twisted away from the attached pyridine ring by 11.4 (3)°.

In the title complex, [Zn(C(8)H(5)O(3))(2)(C(10)H(14)N(2)O)(2)(H(2)O)(2)], the Zn(II) cation is located on an inversion center and is coordinated by two 4-formyl-benzoate anions, two N,N-diethyl-nicotinamide (DENA) ligands and two water mol-ecules. The four O atoms in the equatorial plane around the Zn(II) cation form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two N atoms of the DENA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 2.96 (11)°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 79.26 (4)°. The coordinating water mol-ecule links with the carboxyl-ate group via an intra-molecular O-H⋯O hydrogen bond. In the crystal, O-H⋯O and weak C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional supra-molecular network. A π-π contact between the parallel pyridine rings of adjacent mol-ecules may further stabilize the crystal structure [centroid-centroid distance = 3.5654 (8) Å].

In the title complex, [Zn(C(8)H(5)O(3))(2)(C(6)H(6)N(2)O)(2)(H(2)O)(2)], the Zn(II) cation is located on an inversion center and is coordinated by two 4-formyl-benzoate (FB) anions, two nicotinamide (NA) ligands and two water mol-ecules. The four O atoms in the equatorial plane around the Zn(II) cation form a slightly distorted square-planar arrangement, while the slightly distorted octa-hedral coordination is completed by the two N atoms of the NA ligands in the axial positions. The dihedral angle between the carboxyl-ate group and the adjacent benzene ring is 24.13 (8)°, while the pyridine ring and the benzene ring are oriented at a dihedral angle of 88.52 (4)°. The coordinating water mol-ecule links with the carboxyl-ate group via an O-H⋯O hydrogen bond. In the crystal, N-H⋯O and O-H⋯O hydrogen bonds, and a weak C-H⋯π inter-action link the mol-ecules into a two-dimensional network parallel to (010). These networks are linked via C-H⋯O and π-π inter-actions between inversion-related benzene rings [centroid-centroid distance = 3.8483 (7) Å], forming a three-dimensional supra-molecular structure.

The asymmetric unit of the polymeric title compound, [Co(C(7)H(4)IO(2))(2)(H(2)O)(2)](n), contains one Co(II) cation, two iodo-benzoate anions and two water mol-ecules. One iodo-benzoate anion and one water mol-ecule bridge adjacent Co cations, forming a polymeric chain running along the a axis, while the other iodo-benzoate anion and water mol-ecule coordinate in a monodentate manner to the Co(II) cation, completing the slightly distorted octa-hedral geometry. In the two independent anionic ligands, the carboxyl-ate groups are twisted away from the attached benzene rings by 51.38 (18) and 39.89 (11)°, and the two benzene rings are nearly perpendicular to each other with a dihedral angle of 86.09 (10)°. Intra-molecular O-H⋯O hydrogen bonds between coordinating water mol-ecules and adjacent carboxyl-ate O atoms help to stabilize the mol-ecular structure. In the crystal, weak C-H⋯O hydrogen bonds link the polymeric chains into a three-dimentional supra-molecular network.

In the centrosymmetric binuclear title complex, [Cu(2)(C(7)H(4)IO(2))(4)(H(2)O)(2)], the two Cu(II) ions [Cu⋯Cu = 2.6009 (5) Å] are bridged by four 2-iodo-benzoate (IB) ligands. The four nearest O atoms around each Cu(II) ion form a distorted square-planar arrangement, the distorted square-pyramidal coordination being completed by the O atom of the water mol-ecule at a distance of 2.1525 (16) Å. The dihedral angle between the benzene ring and the carboxyl-ate group is 25.67 (13)° in one of the independent IB ligands and 6.44 (11)° in the other. The benzene rings of the two independent IB ligands are oriented at a dihedral angle of 86.61 (7)°. In the crystal, O-H⋯O inter-actions link the mol-ecules into a two-dimensional network. π-π contacts between the benzene rings [centroid-centroid distances = 3.810 (2) and 3.838 (2) Å] may further stabilize the structure.