The reaction of the ligand 2,3,5,6-tetrakis[(methylsulfanyl)methyl]pyrazine (L1) with silver(I) nitrate led to {[Ag(C12H20N2S4)](NO3)}n, (I),catena-poly[[silver(I)-μ-2,3,5,6-tetrakis[(methylsulfanyl)methyl]pyrazine] nitrate], a compound with a metal–organic chain structure. The asymmetric unit is composed of two half ligands, located about inversion centres, with one ligand coordinating to the silver atoms in a bis-tridentate manner and the other in a bis-bidentate manner. The charge on the metal atom is compensated for by a free nitrate anion. Hence, the silver atom has a fivefold S3N2coordination sphere. The reaction of the ligand 2,3,5,6-tetrakis[(phenylsulfanyl)methyl]pyrazine (L2) with silver(I) nitrate, led to [Ag2(NO3)2(C32H28N2S4)]n, (II), poly[di-μ-nitrato-bis{μ-2,3,5,6-tetrakis[(phenylsulfanyl)methyl]pyrazine}disilver], a compound with a metal–organic network structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. The nitrate anion coordinates to the silver atom in a bidentate/monodentate manner, bridging the silver atoms, which therefore have a sixfold S2NO3coordination sphere. The reaction of the ligand 2,3,5,6-tetrakis[(pyridin-2-ylsulfanyl)methyl]pyrazine (L3) with silver(I) nitrate led to [Ag3(NO3)3(C28H24N6S4)]n, (III), poly[trinitrato{μ6-2,3,5,6-tetrakis[(pyridin-2-ylsulfanyl)methyl]pyrazine}trisilver(I)], a compound with a metal–organic framework structure. The asymmetric unit is composed of half a ligand, located about an inversion centre, that coordinates to the silver atoms in a bis-tridentate manner. One pyridine N atom bridges the monomeric units, so forming a chain structure. Two nitrate O atoms also coordinate to this silver atom, hence it has a sixfold S2N2O2coordination sphere. The chains are linkedviaa second silver atom, located on a twofold rotation axis, coordinated by the second pyridine N atom. A second nitrate anion, also lying about the twofold rotation axis, coordinates to this silver atomviaan Ag—O bond, hence this second silver atom has a threefold N2O coordination sphere. In the crystal of (I), the nitrate anion plays an essential role in forming C—H...O hydrogen bonds that link the metal–organic chains to form a three-dimensional supramolecular structure. In the crystal of (II), the metal–organic networks (lying parallel to thebcplane) stack up thea-axis direction but there are no significant intermolecular interactions present between the layers. In the crystal of (III), there are a number of C—H...O hydrogen bonds present within the metal–organic framework. The role of the nitrate anion in the formation of the coordination polymers is also examined.
The silver(I) nitrate complex of the ligandN-(pyridin-2-ylmethyl)pyrazine-2-carboxamide: a metal–organic framework (MOF) structure
