Bis[5-(pyridin-2-yl)pyrazine-2-carbo­nitrile-κ²N⁴,N⁵](trifluoro­acetato-κO)silver(I)

In the asymmetric unit of the title compound, [Ag(C₁₀H₆N₄)₂(CF₃CO₂)], there two mononuclear but slightly different complex units. In each, two κ²N:N-chelating 5-(pyridin-2-yl)pyrazine-2-carbonitrile ligands surround the Ag^I atom, giving an N₄O square-pyramidal coordination geometry with one trifluoro­acetate O atom at the apex. The difference between the two lies in the Ag—N bond lengths: in one complex, three normal [range 2.272 (5)–2.552 (5) Å] and one long [2.706 (4) Å] and in the second, two normal [2.254 (5) and 2.290 (5) Å] and two long [2.647 (5) and 2.675 (5) Å] are present. Short inter­molecular F...F contacts [2.586 (4) Å] and weak π–π stacking inter­actions [minimum ring centroid separation 3.836 (5) Å] between pyridyl and pyrazinyl rings connect the complex units, forming columns which extend along the b-axis direction.

Poly[[hexa­aqua­(μ₃-2,2′-bipyridine-4,4′,6,6′-tetra­carboxyl­ato-κ⁶O⁴:N,O⁶,O^6′,N′:O^4′)dinickel(II)] dihydrate]

In the title complex, {[Ni₂(C₁₄H₄N₂O₈)(H₂O)₆]·2H₂O}_n, the two Ni^II atoms are located in different special positions (one on a twofold rotation axis and the second on a centre of symmetry) and have different distorted octa­hedral environments (one by two N atoms from a bipyridine unit, two O atoms from two water mol­ecules and two O atoms from two carboxyl­ate groups, and the second by four O atoms from four water mol­ecules and two O atoms from two carboxyl­ate groups). Thus, the environments of the Ni^II atoms may be denoted as NiN₂O₄ and NiO₆. In the crystal, there exists an extensive network of classical O—H...O hydrogen bonds.

3,4,5-Trimeth­oxy­phenol

The asymmetric unit of the title compound, C₉H₁₂O₄, consists of two crystallographically independent mol­ecules with similar conformations: essentially planar [r.m.s deviations for C₆O₄ = 0.0057 and 0.0137 Å] except for the central meth­oxy-methyl group [C—C—O—C torsion angles = 83.3 (2) and 83.9 (2)°]. In the crystal, O—H...O hydrogen bonds link the mol­ecules, generating supra­molecular chains along the b axis.The three-dimensional crystal structure is stabilized by C—H...O and C—H...π inter­actions.