201. Crystal structure of a pyrazine-2,3-dicarboxamide ligand and of its silver(I) nitrate complex, a three-dimensional coordination polymer.
- Author
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Cati, Dilovan S. and Stoeckli-Evans, Helen
- Subjects
CRYSTAL structure ,COORDINATION polymers ,SILVER nitrate - Abstract
The title ligand, C
18 H16 N6 O2 ·2H2 O (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--HNpyrazine hydrogen bond present, forming an S(5) ring motif. In the crystal, adjacent molecules are linked by N--HOcarboxamide hydrogen bonds, forming a chain along [001]. A chain of hydrogen-bonded water molecules is linked to the chain of (L1) molecules by O--HN hydrogen bonds, forming columns propagating along the c axis. The columns are linked by C--HO and C--HN 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(C18 H16 N6 O2 )]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--HO and C--HO hydrogen bonds. [ABSTRACT FROM AUTHOR]- Published
- 2017
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