Why boron does not exist as `B^(2+)` ion in solution or in compound ?

Explanation

Boron has three electrons in its valence shell `(3s^(2) 3p^(1))`. The sum of the first three ionisation enthalpies for boron is very high. Thus, the total energy required to produce `B^(3+)`ion is much more than would be compensated by the hydration enthlpy, and hence `B^(3+)` ion does not exist. The sum of the first three ionistion enthalpies is also not overcome by the lattice enthalpy of the compound in the solid state, and hence `B^(3+)` ion does not exist in the compound.