title: Extremely Long C-C Bond in (-)-trans-1,2-Di-tert-butyl-1,2-diphenyl- and 1,1-Di-tert-butyl-2,2-diphenyl-3,8-dichlorocyclobuta[b]naphthalenes.
abstract: The sterically bulky t-Bu-substituted derivatives of 1,1,2,2-tetraphenyl-3,8-dichlorobuta[b]naphthalene (5), trans-1,2-tert-butyl-1,2-diphenyl- (8) and 1,1-di-tert-butyl-2,2-diphenyl-3,8-dichlorocyclobuta[b]naphthalene (12), were prepared. X-ray analysis of 8 and 12 at 150 K showed that C-C bonds of 8 and 12 are 1.686 and 1.729 Å, respectively. The latter bond length is longer than that of 1.720 Å in 5 and is the longest one reliably determined to date.
authors.affiliation: Department of Applied Chemistry, Faculty of Engineering, Ehime University, Matsuyama 790-8577, Japan, and Department of Chemistry, Faculty of Science, Osaka City University, Sugimoto-cho, Sumiyoshi-ku, Osaka 950, Japan.
authors.forename: Fumio
authors.initials: F
authors.lastname: Toda
authors.forename: Koichi
authors.initials: K
authors.lastname: Tanaka
authors.forename: Masaki
authors.initials: M
authors.lastname: Watanabe
authors.forename: Kenichi
authors.initials: K
authors.lastname: Tamura
authors.forename: Ikuko
authors.initials: I
authors.lastname: Miyahara
authors.forename: Tadashi
authors.initials: T
authors.lastname: Nakai
authors.forename: Ken
authors.initials: K
authors.lastname: Hirotsu