Triaminotriborane(3): A Homocatenated Boron Chain Connected by B−B Multiple Bonds

• Published in: Angewandte Chemie 2017-11, Vol.129 (48), p.15436-15442
• Main Authors: Morisako, Shogo, Shang, Rong, Yamamoto, Yohsuke, Matsui, Hiroshi, Nakano, Masayoshi
• Format: Article
• Language: English
• Subjects: Atomic structure; Boron; Chains; Chemical bonds; Chemistry; Computer applications; Crystals; Diboran-Dianionen; Dichtefunktionalrechnungen; Mehrfachbindungen; Niederkoordiniertes Bor; Reduction; Single crystals; Sodium; X-ray diffraction; π-Delokalisierung
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201708215

A triaminotriborane(3) was isolated as purple crystals through the reduction of (TMP)BCl2 (TMP=2,2,6,6‐tetramethylpiperidino) by sodium naphthalenide. Single‐crystal X‐ray diffraction and computational studies of the obtained triaminotriborane(3) revealed a bent structure of the [B(NR2)]3 chain. The bond lengths between the central and terminal boron atoms were similar to those observed in neutral diborene species. The multiple‐bonding character may be best described by a three‐center two‐electron π‐bond along the B3 chain. The distance between the two terminal boron atoms (2.177 Å) in the solid‐state structure implies a weak interaction between them. When an excess amount of Li was used as the reducing agent, the reaction yielded an unusual dianionic species. The isolation and characterization of these two reduction products are reported herein. Kein schwächstes Glied: Ein Triaminotriboran(3) wurde durch Reduktion von Dichlor(2,2,6,6‐tetramethylpiperidino)boran synthetisiert und vollständig charakterisiert (siehe Schema). Die B‐B‐B‐Kette besteht aus Bor‐Bor‐Mehrfachbindungen; Experimente und Rechnungen zeigen außerdem eine Drei‐Zentren‐zwei‐Elektronen‐π‐Bindung außerhalb der Ebene der B3‐Kette.