Synthesis of several di- and trispiro cyclic siliconmethylene compounds: X-ray crystal structure of 5,7,13-trisila-trisipiro [4.1.4.1.4.1]octadecane and 6,8,15-trisila-trispiro[5.1.5.1.5.1]heneicosane

Very Large Silacylic Substituent Effects on Response in Silole-Based Polymer Transistors

“…The exocyclic silacyclopentane ring is twisted and the distance between atoms C25 and C28 is 2.774 Å, while the theoretical distance from DFT calculations is 2.822 Å. The twisted confomation of the silacyclopentane is similar to that of other reported silacylopentanes. ,, In regard to packing, the conjugated backbones of the SM3 molecules are partially π−π stacked in a slipped cofacial orientation along the b axis. The minimum π−π distance between the closest thiophene rings is ∼3.78 Å.…”

“…The silacyclohexane ring adopts a chair conformation with a distance between C25 and C29 of 2.971 Å, while the theoretical distance from the DFT calculation is 2.993 Å. Such a chair confomation of the silacyclohexane substituent has been observed in related molecules. − As can be seen in Figure , the backbones of successive SM4 molecules assemble in a slipped herringbone conformation along the a axis with a minimum cofacial distance between the closest thiophene rings of 5.24 Å, which is significantly larger than that in SM3 . For compound SM5 having two Si- n -hexyl chains, the backbone is significantly twisted with thiophene-thiophene twist angles of 31.7, 25.3, 2.8, 21.8, and 27.3° on going from ring 1 to 6, respectively, indicating weak intramolecular π conjugation.…”