Crystal and molecular structure of 4,7-di-(2-thienyl)-4,5,6,7-tetrahydrobenzo[b]thiophen

Abstract

The crystal structure of the title compound, the ‘pentamer’ fraction of the acid-catalysed polymerisation of thiophen, has been determined by direct methods from three-dimensional photographic data. The crystals are monoclinic, space group, P2₁/c(C⁵_2h), with a= 14·13, b= 7·68, c= 13·78 Å and β= 104·1°. The disordered structure has been refined by least-squares methods to R 0·111 over 2307 independent reflexions. The cyclohexene ring adopts the half-chair conformation with the thienyl substituents in a cis-configuration.