In the crystal of the title polymeric compound, [CdBr2(C12H12N2)]n, the CdII cation is located on a twofold rotation axis and is six-coordinated in a distorted octa­hedral geometry formed by two N atoms from the 4,4′-dimethyl-2,2′-bipyridine ligand and by four bridging Br− anions. The bridging function of the Br− anions leads to a polymeric chain running along the c axis. Weak C—H⋯π inter­actions observed between adjacent chains are effective in the stabilization of the three-dimensional packing.

In the title compound, [CdI2(C12H12N2)(C3H7NO)], the CdII cation is five-coordinated in a distorted trigonal–bipyramidal configuration by two N atoms from a 4,4′-dimethyl-2,2′-bipyridine ligand, one O atom from a dimethyl­formamide ligand and two I− anions. π–π stacking between pyridine rings of adjacent mol­ecules [centroid–centroid distance = 3.666 (3) and 3.709 (4) Å] stabilizes the three-dimensional structure

The title compound, [Cd2Br4(C24H16N2)2], consists of a centrosymmetric dimeric unit in which two Br atoms bridge two CdII atoms, forming a four-membered ring. A terminal Br atom and a bidentate chelating 4,7-diphenyl-1,10-phenanthroline ligand complete a square-pyramidal geometry for the CdII atom. In the crystal, C—H⋯Br hydrogen bonds and π–π contacts between the pyridine and phenyl rings [centroid–centroid distances = 3.704 (4) and 3.715 (4) Å] lead to a three-dimensional supra­molecular structure.

In the mol­ecule of the title compound, [CoBr2(C11H10N2)], the CoII atom is four-coordinated in a distorted tetra­hedral geometry by two N atoms from a chelating 6-methyl-2,2′-bipyridine ligand and two terminal Br atoms. In the crystal, π–π stacking inter­actions between the pyridine rings along the a-axis direction [centroid–centroid distance = 3.761 (7) Å] and C—H⋯Br hydrogen bonds in the bc plane together generate the three-dimensional packing.

The asymmetric unit of the title compound, [InCl3(C12H12N2)(C3H7NO)]·0.5H2O, contains two independent InIII complex mol­ecules with similar structures and one lattice water mol­ecule. In each complex mol­ecule, the InIII atom is six-coordinated in a distorted octa­hedral geometry, formed by two N atoms from the chelating 5,5′-dimethyl-2,2′-bipyridine ligand, one O atom from a dimethyl­formamide and three facial Cl atoms. In the crystal, the lattice water mol­ecule is linked to the complex mol­ecules via O—H⋯Cl hydrogen bonds. Further weak C—H⋯Cl and C—H⋯O hydrogen bonds result in the formation of a three-dimensional structure.

In the title compound, [CoBr2(C14H12N2)]·CH3CN, the CoII atom is four-coordinated in a distorted tetra­hedral geometry by two N atoms from a chelating 2,9-dimethyl-1,10-phenanthroline ligand and two terminal Br atoms. In the crystal, π–π contacts between the pyridine and benzene rings [centroid–centroid distances = 3.828 (5), 3.782 (5), 3.880 (5) and 3.646 (5) Å] stabilize the structure.

In the title compound, [CoBr2(C12H12N2)], the CoII atom is four-coordinated in a distorted tetra­hedral geometry by two N atoms from a 6,6′-dimethyl-2,2′-bipyridine ligand and by two terminal Br atoms. Inter­molecular C—H⋯Br hydrogen bonds and π–π stacking between the pyridine rings in the bc plane [centroid–centroid distance = 3.725 (3) Å] are present in the crystal structure.

In the title compound, [In(C11H10N2)Cl3(C2H6OS)], the InIII cation is six-coordinated in a distorted octa­hedral configuration by two N atoms from the chelating 6-methyl-2,2′-bipyridine ligand, one O atom from a dimethyl­sulfoxide group and three Cl− anions. Weak inter­molecular C—H⋯O and C—H⋯Cl hydrogen bonds and intra­molecular C—H⋯Cl hydrogen bonds are present in the structure.

In the title compound, [VClO(C12H12N2)2]Cl·C2H5OH·H2O, the VIV atom is six-coordinated in a distorted octa­hedral geometry by four N atoms from two 4,4′-dimethyl-2,2′-bipyridine ligands, one O atom and one Cl atom. In the crystal, O—H⋯Cl, C—H⋯O and C—H⋯Cl hydrogen bonds and π–π contacts between the pyridine rings [centroid–centroid distances = 3.7236 (17) and 3.6026 (19) Å] stabilize the structure. Intra­molecular C—H⋯O and C—H⋯Cl hydrogen bonds are also present.

In the title compound, [InCl3(C10H9N3)(C2H6OS)], the InIII atom is six-coordinated in a distorted octa­hedral geometry by two N atoms from a chelating di-2-pyridyl­amine ligand, one O atom from a dimethyl sulfoxide ligand and three Cl atoms. Inter­molecular C—H⋯Cl hydrogen bonds and π–π contacts between the pyridine rings [centroid–centroid distance = 3.510 (3) Å] are present in the crystal.

In the title compound, [InCl3(C12H12N2)(CH3OH)]·CH3OH, the InIII atom is six-coordinated in a distorted octa­hedral geometry by two N atoms from a chelating 4,4′-dimethyl-2,2′-bipyridine ligand, one O atom from a methanol mol­ecule and three Cl atoms. In the crystal, inter­molecular O—H⋯O and O—H⋯Cl hydrogen bonds link the complex and solvent methanol mol­ecules. Intra­molecular C—H⋯Cl hydrogen bonds are also present in the complex.

In the title compound, [CdBr2(C12H12N2)], the CdII atom is four-coordinated in a distorted tetra­hedral geometry by two N atoms from a 6,6′-dimethyl-2,2′-bipyridine ligand and two terminal Br atoms. In the crystal, C—H⋯Br hydrogen bonds and π–π stacking inter­actions between the pyridine rings [centroid–centroid distance = 3.763 (5) Å] are present.

In the title compound, [CdBr2(C11H10N2)(C2H6OS)], the CdII atom is five-coordinated in a distorted trigonal–bipyramidal geometry by two N atoms from a 6-methyl-2,2′-bipyridine ligand, one O atom from a dimethyl sulfoxide ligand and two Br atoms. An intra­molecular C—H⋯O hydrogen bond occurs. The crystal structure is stabilized by C—H⋯Br hydrogen bonds and π–π contacts between the pyridine rings [centroid–centroid distances = 3.582 (5) and 3.582 (5) Å].

In the title mol­ecule, [Cd(CH3COO)2(C6H6N2O)2], the CdII cation is N,N′-chelated by two 2-pyridine­aldoxime ligands and coordinated by two acetate anions in a distorted octa­hedral geometry. The hy­droxy groups of the 2-pyridine­aldoxime ligands link to the acetate anions via intra­molecular O—H⋯O hydrogen bonds. Weak inter­molecular C—H⋯O hydrogen bonds occur in the crystal.

In the crystal of the title polymeric compound, [Cu2(SO4)2(C5H5N3O)2(H2O)4]n, two independent CuII atoms are located on individual inversion centers. One CuII atom is coordinated by four water mol­ecules and two pyrazine-2-carboxamide ligands in a distorted O4N2 octa­hedral geometry; the other is N,O-chelated by two pyrazine-2-carboxamide ligands and further coordinated by two sulfate anions in a distorted O4N2 octa­hedral geometry. The pyrazine-2-carboxamide ligands bridge the CuII atoms to form a polymeric chain running along [110]. The crystal structure features N—H⋯O, O—H⋯O and weak C—H⋯O hydrogen bonds.

In the title compound, [CdBr2(C12H12N2)(C2H6OS)], the CdII atom is five-coordinated in a distorted trigonal–bipyramidal geometry by two N atoms from one 4,4′-dimethyl-2,2′-bipyridine (DMBP) ligand, one O atom from a dimethyl sulfoxide (DMSO) ligand and two Br atoms. A weak intra­molecular C—H⋯O hydrogen bond occurs between the DMBP and DMSO ligands. π–π stacking between pyridine rings [centroid–centroid distances = 3.682 (3) and 3.598 (3) Å] is observed in the crystal.

In the title compound, [Cd(NO3)2(C5H5N3O)2(H2O)2]·2C5H5N3O, the CdII cation is located on a twofold rotation axis and is coordinated by two pyrazine-2-carboxamide ligands and two water mol­ecules and chelated by two nitrate anions in a distorted square-anti­prismatic geometry. Extensive inter­molecular N—H⋯O, N—H⋯N, O—H⋯O and O—H⋯N hydrogen bonds, as well as weak inter­molecular C—H⋯N and C—H⋯O inter­actions occur in the crystal. π–π stacking between between pyrazine rings of coordinating ligands and lattice molecules [centroid–centroid distance = 3.5669 (14) Å] may further stabilize the structure.

In the crystal of the title polymeric compound, [CdBr2(C12H12N2)]n, the CdII cation is located on a twofold rotation axis. The CdII cation is six-coordinated in a distorted octa­hedral geometry formed by two N atoms from the 5,5′-dimethyl-2,2′-bipyridine ligand and four bridging Br− anions. The bridging function of the Br− anions leads to a polymeric chain running along the c axis.

In the title coordination polymer, [Hg(NCS)2(C4H5N3)], the HgII atom is four-coordinated by one aromatic N atom from a 2-amino­pyrimidine ligand, one S atom from a terminal thio­cyanate ligand, and one S atom and one N atom from a bridging thio­cyanate ligand. The crystal structure features polymeric chains running along the b axis which are stabilized by N—H⋯N hydrogen bonds.

In the crystal of the title compound, {[Zn(C5H5N3O)2(H2O)](NO3)2}n, the ZnII cation is N,O-chelated by two pyrazine-2-carboxamide (PCA) ligands and is further coordinated by one water mol­ecule and by one pyrazine-N atom from an adjacent PCA ligand in a distorted ZnN3O3 octa­hedral geometry. One of the two independent PCA ligands bridges two ZnII cations, forming a zigzag polymeric chain running along the c axis. In the crystal, the NO3 − anions link to the chain via O—H⋯O and N—H⋯O hydrogen bonding. Weak inter­molecular C—H⋯O inter­actions also occur.

In the crystal of the title compound, [ZnCl2(C5H5N3O)2], the mol­ecule has m symmetry, with the ZnII cation and Cl− anions located on the mirror plane. The ZnII cation is coordinated by two Cl− anions and two pyrazine-2-carboxamide ligands in a distorted ZnCl2N2 tetra­hedral geometry. The two pyrazine rings are nearly perpendicular to each other [dihedral angle = 86.61 (10)°]. Inter­molecular N—H⋯O and N—H⋯N hydrogen bonds and weak C—H⋯O inter­actions stabilize the crystal packing.

In the title compound, [HgCl2(C6H5NO2)2]n, the HgII cation is located on an inversion center and is six-coordinated in a distorted octa­hedral geometry by two N atoms from two pyridine-3-carb­oxy­lic acid mol­ecules and four bridging Cl− anions. The bridging function of the Cl− anions leads to polymeric chains running along the a axis. One Hg—Cl bond is much longer than the other. In the crystal, O—H⋯O and weak C—H⋯Cl hydrogen bonds are observed.

The title complex, [ZnBr2(C5H5N3O)2], shows crystallographic mirror symmetry with the Zn atom and the two bromine ligands located on the mirror plane. The Zn atom is four-coordinated in a distorted tetra­hedral fashion by two N atoms from two pyrazine-2-carboxamide ligands and two Br atoms. Only one of the amino H atoms is involved in an N—H⋯O hydrogen bond. The crystal packing is further stabilized by weak N—H⋯N and C—H⋯O inter­actions.

In the crystal of the title polymeric compound, [HgI2(C4H5N3)]n, the HgII cation is located on a twofold rotation axis and is coordinated by two I− anions and two 2-amino­pyrazine ligands in a distorted HgI2N2 tetra­hedral geometry. In the crystal, the 2-amino­pyrazine ligand is equally disordered over two positions about an inversion center, and bridges the HgII cations with pyrazine N atoms to form a polymeric chain running along the c axis. In the polymeric chain, the amino groups link to the coordinated I− anions via inter­molecular N—H⋯I hydrogen bonds.

In the title compound, [Zn(NO3)2(C12H12N2)(H2O)], the ZnII atom is six-coordinated in a distorted octa­hedral geometry by two N atoms from a chelating 4,4′-dimethyl-2,2′-bipyridine ligand, one water O atom, one O atom from a monodentate nitrate anion and two O atoms from a chelating nitrate anion. In the crystal, there are aromatic π–π contacts between the pyridine rings [centroid–centroid distances = 3.9577 (13) Å] and inter­molecular O—H⋯O and C—H⋯O hydrogen bonds.