Dibromidobis(pyrazine-2-carboxamide-κN(4))zinc

catena-Poly[[tetra-aqua-copper(II)]-μ-pyrazine-2-carboxamide-κ(3)N(4):N(1),O-[bis-(sulfato-κO)copper(II)]-μ-pyrazine-2-carboxamide-κ(3)N(1),O:N(4)]

In the crystal of the title polymeric compound, [Cu(2)(SO(4))(2)(C(5)H(5)N(3)O)(2)(H(2)O)(4)](n), two independent Cu(II) atoms are located on individual inversion centers. One Cu(II) atom is coordinated by four water mol-ecules and two pyrazine-2-carboxamide ligands in a distorted O(4)N(2) octa-hedral geometry; the other is N,O-chelated by two pyrazine-2-carboxamide ligands and further coordinated by two sulfate anions in a distorted O(4)N(2) octa-hedral geometry. The pyrazine-2-carboxamide ligands bridge the Cu(II) 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.

Diaqua-bis-(nitrato-κ(2)O,O')bis-(pyrazine-2-carboxamide-κN(4))cadmium-pyrazine-2-carboxamide (1/2)

In the title compound, [Cd(NO(3))(2)(C(5)H(5)N(3)O)(2)(H(2)O)(2)]·2C(5)H(5)N(3)O, the Cd(II) cation is located on a twofold rotation axis and is coordinated by two pyrazine-2-carboxamide ligands and two water mol-ecules and chelated by two nitrate anions in a distorted square-anti-prismatic geometry. Extensive inter-molecular N-H⋯O, N-H⋯N, O-H⋯O and O-H⋯N hydrogen bonds, as well as weak inter-molecular C-H⋯N and C-H⋯O inter-actions 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.