Short N⋯O hydrogen bonds in the 1:1 adduct of 4,4′-bipyridyl and oxalic acid

✍ Scribed by Cowan, John A. ;Howard, Judith A. K. ;Puschmann, Horst ;Williams, Ian D.

• Publisher: International Union of Crystallography
• Year: 2007
• Tongue: English
• Weight: 202 KB
• Volume: 63
• Category: Article
• ISSN: 1600-5368
• DOI: 10.1107/s1600536807005156

✦ Synopsis

Oxalic acid, C~2~O~4~H~2~, and 4,4′-bipyridyl, C~10~H~8~N~2~, crystallize in a 1:1 ratio. The asymmetric unit consists of one oxalic acid (OXA) molecule and one 4,4'bipyridyl (BPY) molecule in general positions, together with one half-OXA molecule and one half-BPY molecule; the latter two molecules are centrosymmetric. The molecules are linked in two parallel independent chains by strong O—H...N hydrogen bonds. In one chain there is one independent O—H...N hydrogen bond [N...O = 2.557 (3) Å] and the molecules lie on centres of symmetry and are therefore constrained to have planar central portions. The second chain contains two independent O—H...N hydrogen bonds [O...N = 2.549 (3) and 2.581 (3) Å] and both molecules are twisted about their central bonds.