The chemistry of perhalo-1,3,5,7-tetrahydrobenzo-[1,2-c:4,5-c′]-difuran: unusually stable solid state complexes with tertiary amides

The base catalyzed reactions of perfluoro-1,3,5,7-tetrahydrobenzo[1,2-c;4,5-c′]difuran (1) and 4,8-dichloro-perfluoro-1,3,5,7-tetrahydrobenzo[1,2-c;4,5-c′]difuran (3) with tertiary amides gave chemically and thermally stable crystalline complexes 2a-e and 4a-d, respectively. The X-ray structure determination of 2c has shown the shortest known intermolecular CO…phenol H-bonding distance and the shortest CO…F non-bonding interaction.