The Telluraboranes closo‐TeB5Cl5 and closo‐TeB11Cl11 with Exceptionally Long Body Diagonals: Synthetic and Bonding Motifs for Innovative Octahedral and Icosahedral Geometries

• Published in: Angewandte Chemie International Edition Vol. 62; no. 24
• Main Authors: Keller, Willi, Ballmann, Joachim, Sárosi, Menyhárt B., Fanfrlík, Jindřich, Hnyk, Drahomír
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 12-06-2023
• Edition: International ed. in English
• Subjects: 4c-2e Bonding; Apexes; Bonding; DFT Calculations; Mass spectroscopy; NMR; Nuclear magnetic resonance; Polyhedra; Pyrolysis; Solid-State Chemistry; Telluraboranes
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202219018

Six‐vertex closo‐TeB5Cl5 (1) and twelve‐vertex closo‐TeB11Cl11 (2) telluraboranes have been prepared via co‐pyrolysis of B2Cl4 with TeCl4 in vacuo at temperatures between 360 °C and 400 °C. Both compounds are sublimable, off‐white solids, and they have been characterized by one‐ and two‐dimensional 11B NMR and high‐resolution mass spectroscopy. Both ab initio/GIAO/NMR and DFT/ZORA/NMR computations support octahedral and icosahedral geometries for 1 and 2, respectively, as expected due to their closo‐electron counts. The octahedral structure of 1 has been confirmed by single‐crystal X‐ray diffraction on an incommensurately modulated crystal. The corresponding bonding properties have been analyzed in terms of the intrinsic bond orbital (IBO) approach. 1 is the first example of a polyhedral telluraborane with a cluster size smaller than 10 vertices.
The formation of the first small‐sized polyhedral telluraborane, i.e. closo‐TeB5Cl5, has been achieved in a two‐component, one‐pot thermal reaction of diboron tetrachloride and tellurium tetrachloride. The co‐pyrolysis also generates the icosahedral closo‐TeB11Cl11. The assembly of electron‐deficient polyhedral frameworks from small, electron‐precise precursory molecules provides a unique entry into the field of heteroatom‐containing boranes.