How molecular orbital theoryexplain the octahedral complexes?
Molecular Orbital Theory is a way of combining atomic orbitals to form bonding orbitals, non-bonding orbitals and antibonding orbitals. You then use available electrons to fill the bonding orbitals. These will be directed in space in common geometric arrangements, linear, trigonal, tetrahedral, trigonal bipyramidal, octahedral, and so on which will determine the primary shape of the molecule. The non bonding orbitals, if containing electrons, will also affect the shape. Antibonding orbitals need to be kept empty, if not they destabilize the molecule. Octahedral obviously means 6 x 2 electrons = 12, so what happened to the octet rule ? Well, as you go deeper into the periodic table, valence shells can and do accommodate more than 8 electrons, so you won’t find octahedral in the first two rows, but after that the valence shell sharing capacity can jump to 18 and beyond. Its usually spatial limitations that determine just how many shared pairs of electrons can fit around an atom.
