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A new tetra­kis-substituted pyrazine carb­­oxy­lic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetra­yltetra­kis(methyl­ene)]tetra­kis­(sulfanedi­yl)}tetra­propionic acid: crystal structures of two triclinic polymorphs and of two potassium–organic frameworks.

A new tetra­kis-substituted pyrazine carb­­oxy­lic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetra­yltetra­kis(methyl­ene)]tetra­kis­(sulfanedi­yl)}tetra­propionic acid: crystal structures of two triclinic polymorphs and of two potassium–organic frameworks.

Authors :
Pacifico, Jessica
Stoeckli-Evans, Helen
Source :
Acta Crystallographica Section E: Crystallographic Communications; May2021, Vol. 77 Issue 5, Following p480-490, 29p
Publication Year :
2021

Abstract

Two polymorphs of the title tetra­kis-substituted pyrazine carb­oxy­lic acid, 3,3′,3′′,3′′′-{[pyrazine-2,3,5,6-tetra­yltetra­kis­(methyl­ene))tetra­kis­(sulfanedi­yl]}tetra­propionic acid, C<subscript>20</subscript>H<subscript>28</subscript>N<subscript>2</subscript>O<subscript>8</subscript>S<subscript>4</subscript>, (H<subscript>4</subscript>L1), have been obtained, H<subscript>4</subscript>L1_A and H<subscript>4</subscript>L1_B. Each structure crystallized with half a mol­ecule in the asymmetric unit of a triclinic P1̅ unit cell. The whole mol­ecules are generated by inversion symmetry, with the pyrazine rings being located about inversion centers. The crystals of H<subscript>4</subscript>L1_B were of poor quality, but the X-ray diffraction analysis does show the change in conformation of the –CH<subscript>2</subscript>—S—CH<subscript>2</subscript>—CH<subscript>2</subscript>– side chains compared to those in polymorph H<subscript>4</subscript>L1_A. In the crystal of H<subscript>4</subscript>L1_A, mol­ecules are linked by two pairs of O—H⋯O hydrogen bonds, enclosing R<subscript>2</subscript>²(8) ring motifs forming layers parallel to plane (100), which are linked by C—H⋯O hydrogen bonds to form a supra­molecular framework. In the crystal of H<subscript>4</subscript>L1_B, mol­ecules are also linked by two pairs of O—H⋯O hydrogen bonds enclosing R<subscript>2</subscript>²(8) ring motifs, however here, chains are formed propagating in the [001] direction and stacking up the a-axis. Reaction of H<subscript>4</subscript>L1 with Hg(NO<subscript>3</subscript>)<subscript>2</subscript> in the presence of a potassium acetate buffer did not produce the expected binuclear complex, instead crystals of a potassium–organic framework were obtained, poly[(μ-3-{[(3,5,6-tris­{[(2-carb­oxy­eth­yl)sulfan­yl]meth­yl}pyrazin-2-yl)meth­yl]sulfan­yl}propano­ato)potassium], [K(C<subscript>20</subscript>H<subscript>27</subscript>N<subscript>2</subscript>O<subscript>8</subscript>S<subscript>4</subscript>)]<subscript>n</subscript> (KH<subscript>3</subscript>L1). The organic mono-anion possesses inversion symmetry with the pyrazine ring being located about an inversion center. A carb­oxy H atom is disordered by symmetry and the charge is compensated for by a potassium ion. A similar reaction with Zn(NO<subscript>3</subscript>)<subscript>2</subscript> resulted in the formation of crystals of a dipotassium-organic framework, poly[(μ-3,3′-{[(3,6-bis­{[(2-carb­oxy­eth­yl)sulfan­yl]meth­yl}pyrazine-2,5-di­yl)bis(methyl­ene)]bis­(sulfanedi­yl)}dipropionato)dipotassium], [K<subscript>2</subscript>(C<subscript>20</subscript>H<subscript>26</subscript>N<subscript>2</subscript>O<subscript>8</subscript>S<subscript>4</subscript>)]<subscript>n</subscript> (K<subscript>2</subscript>H<subscript>2</subscript>L1). Here, the organic di-anion possesses inversion symmetry with the pyrazine ring being located about an inversion center. Two symmetry-related acid groups are deprotonated and the charges are compensated for by two potassium ions. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
20569890
Volume :
77
Issue :
5
Database :
Complementary Index
Journal :
Acta Crystallographica Section E: Crystallographic Communications
Publication Type :
Academic Journal
Accession number :
150195773
Full Text :
https://doi.org/10.1107/S2056989021003479