19259-11-1Relevant articles and documents
Revisiting Dehydrothiopheno[12]annulenes: Synthesis, Electronic Properties, and Aromaticity
Ohtomo, Yasuhiro,Ishiwata, Ken,Hashimoto, Shingo,Kuroiwa, Tatsuru,Tahara, Kazukuni
, p. 13198 - 13211 (2021/10/12)
The aromaticity and electronic properties of acetylene-bridged hexadehydrotristhiopheno[12]annulenes (HDTAs) were revisited using a combined experimental and theoretical approach. Moreover, we attempted the synthesis of the butadiyne-bridged octadehydrobisthiopheno[12]annulenes (ODTAs). While the formation of ODTAs was indicated by NMR spectroscopy, mass spectrometry, and UV-vis absorption measurements, our attempts to isolate ODTAs were unsuccessful on account of its instability. Instead, their structure and energetic properties were predicted using DFT calculations. HDTA isomers in which the position where the thiophene rings are fused to the 12-membered ring differs (b- vs c-position) show distinct differences in their HOMO-LUMO energy gaps (EGap). ODTAs also show large EGap differences depending on the fusion position of the thiophene rings. The diene character of the thiophene ring significantly changes the electronic properties; i.e., EGap differences of >1 eV were observed between the isomers of both HDTAs and ODTAs. A theoretical evaluation of HDTAs and ODTAs revealed significant variation in the local aromaticity/antiaromaticity between the b- and c-isomers. The antiaromatic character of the 12-membered ring is attenuated for the b-isomers, whereas it is decreased substantially for the c-isomers. The results of this study are useful for a detailed understanding of the fundamental aspects of dehydrothiopheno[12]annulenes.
A Convenient Synthesis of Dithieno[3,2- b:2′,3′- d ]thiophenes from Thiophene
Park, Kyung Hyun,Park, Joon Bum,Zong, Kyukwan
, p. 4126 - 4130 (2016/11/26)
A new synthetic method for dithieno[3,2-b:2′,3′-d]thiophenes was developed. The approach involves three steps starting from thiophene: tetraiodation of thiophene, selective dialkynylations on the 2,5-positions of the tetraiodothiophene, and finally CuI/TMEDA catalyzed double annulations of 2,5-dialkynyl-3,4-diiodothiophenes by Na2S, to afford dithieno[3,2-b:2′,3′-d]thiophene and its derivatives.
Interaction in molecular crystals, 166 [1, 2]. Polyiodo molecules I2C=CI2, (IC)4S, (IC)4NH, (IC)4N-CH3 and HCI3: Structure determination following crystallization or by Density Functional Theory calculation
Bock, Hans,Holl, Sven,Krenzel, Volker
, p. 13 - 24 (2007/10/03)
The structures of tri- and tetraiodo-substituted carbon compounds are determined either experimentally by X-Ray Structure Analysis or, because crystallization of tetraiodothiophene could not be achieved, approximated by Density Functional Theory optimization of structural data from a donor/acceptor complex. The structures show noteworthy details such as a second polymorph of tetraiodoethene crystallized by sublimation or herringbone crystal packing patterns of tetraiodopyrrole derivatives. All molecular geometries are discussed and compared based on relativistic density functional theory calculations with 6-31G* basis sets including iodine pseudopotentials. They reproduce even finer structural details due to van der Waals repulsion of the bulky iodo substituents. Natural Bond Orbital (NBO) charge distributions suggest positive partial charges at all iodine centers with the strongest polarization Cδ →Iδ⊕ in HCI3, which contains well over 97% iodine.
