176.

Draw figure to show splitting of d orbitals in an octahedral crystal field.

Crystal field effects in octahedral coordination entities:

(i) Let us assume that the six ligands are positioned symmetrically along the cartesian axes, with metal atom at the origin. As the ligands approach first there is an increase in energy of d-orbitals relative to that of the free ion just as would be the case in a spherical field.

(ii) The orbitals lying along the axes (d_z² , and d_{x²– y²}) get repelled more strongly than d _xy’, d _yz. and d _zx orbitals which have lobes directed between the axes.


Fig. d-orbital splitting in an octahedral crystal field.

The d_z² , and d_{x²– y²} orbitals get raised in energy and d_xy, d_yz, d_xz orbitals are lowered in energy relative to the average energy in the spherical crystal field.

Thus, the degenerate set of d-orbitals get split into two sets: the lower energy orbitals set t_2g and the higher field energy orbitals e_g set. The energy is separated by Δ₀.