Crystal structure of 4,4′,3″,4‴‐Tetramethyl2,2′:5′,2″:5″,2‴‐tetrathiophene: A comparison with the conformation in solution

Are thiophene rings and chains more easily deformed than those in polyphenylene, polyfuran and polypyrrole? The conformation has great influence on the conjugation lenght of the polymers and therefore on their optical and electronic properites. Data obtained from an extremely rare X‐ray structure determination of an α, α'‐conjugated oligothiophene is comapared with that obtained from solution studies and both are discussed in light of MMP2 force‐field calculations.