Question

When a metal cation forms an octahedral complex the ligands approach directly along the x, y, and z axes. the two d orbitals with lobes along the axes will experience a_______repulsion than the three d orbitals with lobes between the axes. the d _____ orbitals will be split into two groups; the higher energy group has_____orbitals and the lower energy group has orbitals.

a. lower; three; two
b. lower; two; three
c. greater; two; three
d. greater; three; two

Answer 1

In an octahedral complex, the eg orbitals (dx² - y² and d₂²) experience greater repulsion and are higher in energy due to direct alignment with the ligands, resulting in two higher energy orbitals, while the t2g orbitals (dxy, dxz, and dyz) point between the ligands and have three lower energy orbitals.

Step-by-step explanation:

When a metal cation forms an octahedral complex, the ligands approach along the x, y, and z axes. This interaction causes a split in the energies of the five d orbitals. The two d orbitals with lobes along the axes experience a greater repulsion than the three d orbitals with lobes between the axes.

The d orbitals pointing directly at the ligands are the eg orbitals (dx² - y² and d₂²), which will be higher in energy due to electrostatic repulsions with the approaching negative ligands. Conversely, the t2g orbitals (dxy, dxz, and dyz) have lobes oriented between the axes, resulting in less repulsion and lower energy levels compared to the eg orbitals. Therefore, in an octahedral complex, the eg orbitals will be split into a higher energy group with two orbitals, and the t2g will form a lower energy group with three orbitals.