This book focuses on the creation and demonstration of a carbon-carbon (C-C) single bond beyond 1.8 Å and on elucidation of its unique nature. C-C single bond is one of the most fundamental concepts in organic chemistry. The elucidation of its nature is important for further understanding chemical phenomena. The nature in the extreme state of C-C single bond is still unexplored because of the instability of compounds. In terms of its bond length, the limit had been predicted around 1.8 Å based on the experimental and theoretical studies. This book describes a first example of a C-C single bond beyond 1.8 Å by employing the original intramolecular core-shell strategy to make a weak and elongated bond stable enough. The presence of such an elongated bond was demonstrated by experimental and theoretical studies. The bond length changes could affect physical properties such as optical absorption and redox potential. Furthermore, its unique 'flexibility' was discovered. This book benefits the chemists with deeper understanding of the covalent bonding.

Takuya Shimajiri was born in Obihiro, Hoakkido Prefecture, Japan in 1994. He graduated from Hokkaido University in 2017 and received his Ph.D. in 2022 under the supervision of Professors Takanori Suzuki. He started his academic career as a specially appointed assistant professor at Hokkaido university in 2022. His research interest is focusing not only on chemical bonds but also on organic p-conjugated systems to elucidate unique chemical phenomena in extreme structures through experimental and theoretical studies.