Ab Initio Studies on Disubstituted closo‐Icosahedral Heteroboranes, X2B10H10 [X = CH, SiH, N, P, and Sb]

Ab initio theoretical studies on X2B10H10 (X = CH, SiH, N, P and Sb) have been done for all the three possible isomers. Unlike lower‐vertex heteroboranes, all the hetero derivatives have shown similar trends in the relative stabilities, the 1,12‐isomer being more stable followed by 1,7‐ and 1,2‐isomers, except for N and Sb. No conventional 1,2‐isomer for N could be found. Instead, a new nido isomer which is 18.1 kcal/mol higher in energy than the most stable isomer has been located. Any hetero group substitution to icosahedral R12H122− is found to be thermodynamically destabilizing. However, the Nucleus Independent Chemical Shift criterion shows that all compounds, except for 8, have similar aromaticity.