Abstract
In dimethyl 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ate, C18H14N4O4, (I), and diethyl 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carboxyl-ate, C20H18N4O4, (II), the dimethyl and diethyl esters of 5,6-bis-(pyridin-2-yl)pyrazine-2,3-di-carb-oxy-lic acid, the orientation of the two pyridine rings differ. In (I), pyridine ring B is inclined to pyrazine ring A by 44.8 (2)° and the pyridine and pyrazine N atoms are trans to one another, while pyridine ring C is inclined to the pyrazine ring by 50.3 (2)°, with the pyridine and pyrazine N atoms cis to one another. In compound (II), the diethyl ester, which possesses twofold rotation symmetry, the pyridine ring is inclined to the pyrazine ring by 40.7 (1)°, with the pyridine and pyrazine N atoms trans to one another. In the crystal of (I), mol-ecules are linked by C-H⋯N hydrogen bonds, forming chains along [001]. The chains are linked by C-H⋯π inter-actions, forming a three-dimensional structure. In the crystal of (II), mol-ecules are linked via C-H⋯O hydrogen bonds, forming a three-dimensional framework. There are C-H⋯π inter-actions present within the framework.
Highlights
50.3 (2), with the pyridine and pyrazine N atoms cis to one another
In compound (II), the diethyl ester, which possesses twofold rotation symmetry, the pyridine ring is inclined to the pyrazine ring by 40.7 (1), with the pyridine and pyrazine N atoms trans to one another
In the crystal of (I), molecules are linked by C—H N hydrogen bonds, forming chains along [001]
Summary
Was synthesized to study its coordination behaviour with first row transitions metals (Alfonso, 1999). It exists as a zwitterion, with the adjacent pyridine and pyridinium rings almost coplanar due to the presence of an intramolecular N—H N hydrogen bond. Metal-catalysed hydrolysis of amino acid esters is a well documented phenomenon (Dugas, 1989). Metal-ion-promoted ester hydrolysis leads to the formation of new ligands and may serve as a general route to prepare new coordination compounds. (I) and (II), were synthesized to study the hydrolysis of these esters with first row transition metals (Alfonso, 1999), and we report on their syntheses and crystal structures
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