Unusual Hydrogen-bonding Networks Consisting of π-Extended 4,4′-Bipyridines and Chloranilic Acid

Abstract

Hydrogen-bonding networks of π-extended 4,4′-bipyridines, 2,5-di(4-pyridyl)thiophene (1), 2,5-di(4-pyridyl)furan (2) and 1,4-di(4-pyridyl)benzene (3) with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, CA) have been investigated. The dipyridyl compounds afforded complexes 4 [(dication of 1)·(monoanion of CA)²], 5 [(dication of 2)·(dianion of CA)·(MeOH)] and 6 [(3)·(dication of 3)·(dianion of CA)·(H²O)⁶] with CA. X-ray structure analyses revealed the formation of unusual molecular tape and sheet structures involving N–H ⃛O, O–H ⃛O, C–H ⃛O and N–H ⃛N hydrogen bonds, where the aromatic spacer groups play an important role in constructing the unique crystal structures.

Keywords:

• Crystal engineering
• Hydrogen-bonding network
• π-Extended bipyridines
• Chloranilic acid

Acknowledgements

This work was supported by a Grant-in-Aid for Scientific Research on Priority Areas from the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Notes

^†The hydrogen bond labeled c in Fig. 1 seems to be a head-on approach of two hydrogen atoms, and the position of the hydrogen atom may be uncertain. Because of the low quality of the crystal, we could not refine the hydrogen atom isotropically.

^‡The solvated methanol is disordered over two sites with occupancies of 0.592(6) and 0.408(6), respectively. The carbon and oxygen atoms of the disordered methanol were localized in the Fourier map and refined isotropically.