The Use of Phosphirenes as Conjugating Spacers in Polythiophene Chains

A series of thienyl-substituted phosphirene P−W(CO)₅ complexes were synthesized by reaction of the transient terminal phosphinidene complex [Ph−P−W(CO)₅] with the appropriate thienyl-substituted alkynes. The X-ray structural study of these complexes shows coplanar thiophene and phosphirene rings, suggesting a good inter-ring conjugation. A combined ¹³C NMR−NBO analysis indicates that the CC double bond of the phosphirene ring is highly polarizable. UV spectra show a red-shift of the absorption when converting the alkynes into the phosphirenes. CV data are also given.