Structures of XH4+ and XH6+ (X = B, Al and Ga) cations
Structures and energies of XH4+ and XH6+ (X = B, Al and Ga) have been calculated at the density functional theory (DFT) B3LYP/6-311++G(3df,2pd) level. Calculations indicate that although the structure with a three center two electron (3c-2e) bond is the global minimum for BH4+, the global minima of AlH4+ and GaH4+ are not those with one 3c-2e bond, but those with two 3c-2e bonds. For calibration, both structures of AlH4+ were also calculated at the ab initio CCSD(T)/cc-pVTZ level and results in agreement with the DFT results were found. Similar calculations also indicate that although the C-2v symmetrical structure with two 3c-2e bonds is the global minimum for BH6+, the global minima of AlH6+ and GaH6+ are not the C-2v symmetrical structures with two 3c-2e bonds but the C-2 symmetrical structures with three 3c-2e bonds.
density functional calculations boronium ion three center two electron bond