Barriers to rotation of methyl groups in methyltriptycenes

F Imashiro, K Takegoshi, T Terao…

Index: Imashiro, Fumio; Takegoshi, Kiyonori; Terao, Takehiko; Saika, A. Journal of the American Chemical Society, 1982 , vol. 104, # 8 p. 2247 - 2251

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Citation Number: 10

Abstract

Abstract: Rotational barriers of methyl groups in methyltriptycenes are determined from the temperature dependence of the'H spin-lattice relaxation times. Barriers of bridgehead methyls increase appreciably by methyl substitution at peri positions, which suggests probable absence of the gear effect. Calculations by the molecular mechanics (MMI) method and the molecular orbital (CNDO/FK) method favor a clashed-gear conformation for ...