Limits...
Crystal structure of 2-(aza ­ niumylmeth ­ yl)pyridinium bis(hydrogen squarate)

View Article: PubMed Central - HTML - PubMed

ABSTRACT

The asymmetric unit of the title compound, C6H10N22+·2C4HO4−, comprises two hydrogen squarate (Hsq−; systematic name: 2-hy­droxy-3,4-dioxo­cyclo­butano­late) anions and a 2-(aza­niumylmeth­yl)pyridinium dication. The squaric acid mol­ecules each donate an H atom to the N atoms of the pyridine ring and the amino­methyl units of a 2-(amino­meth­yl)pyridine mol­ecule, forming the 1:2 salt. The Hsq− anions are linked by strong O—H⋯O hydrogen bonds and an N—H⋯O hydrogen bond links the 2-(aza­niumylmeth­yl)pyridinium cation to one of the squaric acid anions. The crystal structure features additional N—H⋯O and O—H⋯O hydrogen bonds, π–π stacking and unusual weak C—O⋯π(ring) inter­actions.

No MeSH data available.


A view of the asymmetric unit of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. Dashed lines indicate hydrogen bonds.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5382627&req=5

fig1: A view of the asymmetric unit of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. Dashed lines indicate hydrogen bonds.

Mentions: 2-(Amino­meth­yl) pyridine forms a salt with two squaric acid mol­ecules and each mol­ecule of the acid loses one proton. One of these is transferred to the N atom of the pyridine ring, generating the 4-(amino­meth­yl)morpholinium mono-cation. The other from the second acid mol­ecule is engaged in the formation of a homo-conjugated hydrogen squarate anion via a short, symmetric O5—H5A⋯O3 [2.4583 (14) Å] hydrogen bond (Fig. 1 ▸). The electron density associated with this H atom is shared by the O5 and O3 atoms, indicating a large degree of ionic character (Gilli & Gilli, 2000 ▸). Considering the range (2.38–2.50 Å) of Gilli’s classification for such an inter­action, this hydrogen bonding can be referred to as negative charge-assisted hydrogen bonding [(−) CAHB] (Gilli & Gilli, 2009 ▸; Gilli et al., 2001 ▸; Becke, 1993 ▸, Lee et al., 1988 ▸) and can be represented as [-O⋯H⋯O-]−.


Crystal structure of 2-(aza ­ niumylmeth ­ yl)pyridinium bis(hydrogen squarate)
A view of the asymmetric unit of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. Dashed lines indicate hydrogen bonds.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382627&req=5

fig1: A view of the asymmetric unit of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. Dashed lines indicate hydrogen bonds.
Mentions: 2-(Amino­meth­yl) pyridine forms a salt with two squaric acid mol­ecules and each mol­ecule of the acid loses one proton. One of these is transferred to the N atom of the pyridine ring, generating the 4-(amino­meth­yl)morpholinium mono-cation. The other from the second acid mol­ecule is engaged in the formation of a homo-conjugated hydrogen squarate anion via a short, symmetric O5—H5A⋯O3 [2.4583 (14) Å] hydrogen bond (Fig. 1 ▸). The electron density associated with this H atom is shared by the O5 and O3 atoms, indicating a large degree of ionic character (Gilli & Gilli, 2000 ▸). Considering the range (2.38–2.50 Å) of Gilli’s classification for such an inter­action, this hydrogen bonding can be referred to as negative charge-assisted hydrogen bonding [(−) CAHB] (Gilli & Gilli, 2009 ▸; Gilli et al., 2001 ▸; Becke, 1993 ▸, Lee et al., 1988 ▸) and can be represented as [-O⋯H⋯O-]−.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

The asymmetric unit of the title compound, C6H10N22+·2C4HO4−, comprises two hydrogen squarate (Hsq−; systematic name: 2-hy­droxy-3,4-dioxo­cyclo­butano­late) anions and a 2-(aza­niumylmeth­yl)pyridinium dication. The squaric acid mol­ecules each donate an H atom to the N atoms of the pyridine ring and the amino­methyl units of a 2-(amino­meth­yl)pyridine mol­ecule, forming the 1:2 salt. The Hsq− anions are linked by strong O—H⋯O hydrogen bonds and an N—H⋯O hydrogen bond links the 2-(aza­niumylmeth­yl)pyridinium cation to one of the squaric acid anions. The crystal structure features additional N—H⋯O and O—H⋯O hydrogen bonds, π–π stacking and unusual weak C—O⋯π(ring) inter­actions.

No MeSH data available.