Introduction to Boron Chemistry
Boron has electronic configuration [He]2s22p1, and main formal oxidation state +3.
Its bonding is mainly covalent, and it forms compounds with three bonds, and therefore six electrons in its valence shell: It is electron deficient.
The bonding orbitals are sp2 hybrid orbitals, and the remaining p-orbital on B acts as a pi-acceptor orbital, eg. in BF3 , where the back donation of p-electrons from F to B forms pπ-pπ bonds.
Ionic interactions also occur, and lead to a shortening and strengthening of bonds, eg. in BF4– , where pπ-pπ bonds are absent.
Main sources of Boron are hydrated oxides, like borax (Na2B4O5(OH)4.8H2O). Aluminium, the second element in Group 13, has the primary ore bauxite, containing hydrated aluminium oxide (Al2O3.H2O).
|The π-acceptor nature of B dominates its behavior as a Lewis acid, eg. in the reaction with tri-methylammonium.|