Adamantonium Ions

Adamantonium Ions. There exists a single theoretical study for ada-mantonium ions.850 Mota and co-workers have found three isomeric structures (490-492) and two van der Waals complexes (1-adamantyl cation+ H2 and 2-adamantyl cation + H2) [MP2(full)/6-31G level]. The C—H bond lengths in the 3c-2e interactions in ion 490 are 1.276 and 1.266 A and in ion 491 are 1.266 and 1.280 A. The C-adamantonium ion (492) has nonequivalent C—H bond distances (1.191 and 1.294 A) and the C—C bond distance is 2.348 A. Interestingly, the 2-adamantyl cation + H2 complex shows a nonclassical bonding nature similar to the 

2-norbomyl cation. Cation 492 is the most stable, but it is 9.30 kcal mol 1 less stable than the 1-adamantyl cation + H2 complex. 

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