Abstract
The title ligand, C18H16N6O2·2H2O (L1) [N2,N3-bis-(pyridin-4-ylmeth-yl)pyrazine-2,3-dicarboxamide], crystallized as a dihydrate. The mol-ecule 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 intra-molecular N-H⋯Npyrazine hydrogen bond present, forming an S(5) ring motif. In the crystal, adjacent mol-ecules are linked by N-H⋯Ocarboxamide hydrogen bonds, forming a chain along [001]. A chain of hydrogen-bonded water mol-ecules is linked to the chain of (L1) mol-ecules 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 supra-molecular 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-ylmeth-yl)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 mol-ecule and half a positionally disordered nitrate anion located about a twofold rotation axis. The full mol-ecule of the ligand is generated by twofold rotational symmetry, with this twofold axis bis-ecting 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 mol-ecule. Each silver ion is coordinated by two pyridine N atoms and by two carboxamide O atoms of neighbouring mol-ecules, hence forming a three-dimensional framework. The nitrate anion is linked to the framework by N-H⋯O and C-H⋯O hydrogen bonds.
Highlights
Crystal structure of a pyrazine-2,3-dicarboxamide ligand and of its silver(I) nitrate complex, a threedimensional coordination polymer
Adjacent molecules are linked by N— HÁ Á ÁOcarboxamide hydrogen bonds, forming a chain along [001]
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[[[4-N2,N3-bis(pyridin-4-ylmethyl)pyrazine-2,3-dicarboxamide]silver(I)] nitrate] (I)
Summary
The title ligand, N2,N3-bis(pyridin-4-ylmethyl)pyrazine-2,3dicarboxamide (L1), is one of a series of ligands synthesized in order to study the superexchange in supramolecular complexes formed using pyrazine carboxamide derivatives and first row transition metal ions (Cati, 2002; Cati et al, 2004). It is very similar to the ligand N2,N3-bis(pyridin-2-ylmethyl)pyrazine-2,3-dicarboxamide (L2), for which a number of transition metal complexes have been described, including some interesting tetranuclear 2Â2 grid-like and square complexes (Hausmann et al, 2003; Klingele et al, 2007). Two such complexes, {[Cu4(L2)4](ClO4)4}Á5CH3OHÁ4H2O and {[Ni4(L2)4]Cl4}Á5CH3CNÁ13H2O (Cati et al, 2004), exhibit. With the tetradendate ligand 1,6-bis(2H-1,2,3-triazol-2-yl)hexane, Huo et al (2016) synthesized the three-dimensional coordination polymer, catena-[[-2,20-(butane-1,4-diyl)bis(2H-1,2,3triazole)]bis(-nitrato)disilver] They showed that it exhibits highly selective and sensitive luminescence sensing of Cr2O72À ions in aqueous solution. It is an interesting ligand to study its coordination behaviour with silver nitrate, and we describe the solid state structures of ligand (L1), and the new three-dimensional coordination polymer, poly[[[4-N2,N3-bis(pyridin-4-ylmethyl)pyrazine2,3-dicarboxamide]silver(I)]nitrate] (I)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
