A computational analysis of the apparent nido vs. hypho conflict: are we dealing with six- or eight-vertex open-face diheteroboranes?Dedicated to the memory of Professor Ken Wade.Electronic supplementary information (ESI) available: Cartesian coordinates for the structures of cB11, nB10, and aB9 (Tables S1-S3), 1a-1f (Tables S4-S9), and nido-[B6H11]+ (Table S10), the s character, p character, and resultant hybridisation of 1a-1f for all levels of theory (Tables S11-S13), and charges on the heter

• Main Authors: Nunes, João Pedro F, Holub, Josef, Rankin, David W. H, Wann, Derek A, Hnyk, Drahomír
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt01460c

A series of computational studies have been undertaken to investigate the electronic structures and bonding schemes for six hetero-substituted borane cages, all of which have been presented in the literature as potential hypho structures. The six species are hypho -7,8-[C 2 B 6 H 13 ] − ( 1a ), hypho -7,8-[CSB 6 H 11 ] − ( 1b ), hypho -7,8-[S 2 B 6 H 9 ] − ( 1c ), hypho -7,8-[NSB 6 H 11 ] ( 1d ), exo -7-Me- hypho -7,8-[NCB 6 H 12 ] ( 1e ), and endo -7-Me- hypho -7,8-[NCB 6 H 12 ] ( 1f ) and the so-called mno rule has been applied to each of them. As no structural data are known for the carbathia-, azathia-, and dithiahexaboranes, we have also applied the ab initio /GIAO/NMR structural tool for 1b-1d , with 1c having been prepared for this purpose. We conclude that an mno count of 10 means that 1a , 1b , 1d , 1e , and 1f should be termed pseudo-nido or pseudo-hypho . Only 1c can be considered to be correctly termed hypho -7,8-[S 2 B 6 H 9 ] − . Computational studies have been undertaken to investigate the electronic structures of six hetero-substituted borane cages, concluding that hypho -7,8-[S 2 B 6 H 9 ] − is the only true hypho species in this series.