Question

Describe how the orbitals on a boron atom, in a borane cluster, may be conceptually hybridised in order to explain the bonding.

Answer 1

Solution:

The borane clusters are made up of borane molecules (BH3). The observed structure of the borane molecule, BH3, suggests sp2 hybridization for boron in this compound and molecule is trigonal planar. In clusters, boron forms 2c-2e (terminal B-H bonds) and 3c-2e (banana) bonds. The four orbitals of each boron atom will be hybridized to accommodate the three eletrons (electrons of 2 B-H bonds and shared electrons of 2 banana bonds). Thus hybridisation of boron in clusters is sp3.