| Summary: | The title ligand, C18H16N6O2·2H2O (L1) [N2,N3-bis(pyridin-4-ylmethyl)pyrazine-2,3-dicarboxamide], crystallized as a dihydrate. The molecule is U-shaped with the carboxamide groups being cis to one another, making a dihedral angle of 81.6 (5)°. The terminal pyridine rings are inclined to one another by 58.5 (4)°. There is an intramolecular N—H...Npyrazine hydrogen bond present, forming an S(5) ring motif. In the crystal, adjacent molecules are linked by N—H...Ocarboxamide hydrogen bonds, forming a chain along [001]. A chain of hydrogen-bonded water molecules is linked to the chain of (L1) molecules by O—H...N hydrogen bonds, forming columns propagating along the c axis. The columns are linked by C—H...O and C—H...N hydrogen bonds, forming a three-dimensional supramolecular structure. The reaction of ligand (L1) with silver(I) nitrate led to the formation of a new three-dimensional coordination polymer, {[Ag(C18H16N6O2)]NO3}n, poly[[[μ4-N2,N3-bis(pyridin-4-ylmethyl)pyrazine-2,3-dicarboxamide]silver(I)] nitrate] (I). The asymmetric unit is composed of half of one silver ion, located on a twofold rotation axis, half a ligand molecule and half a positionally disordered nitrate anion located about a twofold rotation axis. The full molecule of the ligand is generated by twofold rotational symmetry, with this twofold axis bisecting the Car—Car bonds of the pyrazine ring and the Ag—Ag bond. The carboxamide groups are now trans to one another, making a dihedral angle of 65.8 (4)°. The two terminal pyridine rings are inclined to one another by 6.6 (3)°. Two ligands wrap around an Ag—Ag bond of 3.1638 (11) Å, forming a figure-of-eight-shaped complex molecule. Each silver ion is coordinated by two pyridine N atoms and by two carboxamide O atoms of neighbouring molecules, hence forming a three-dimensional framework. The nitrate anion is linked to the framework by N—H...O and C—H...O hydrogen bonds.
|
|---|
