Answer: t 2g to eg* transition (technically t 2g to eg MO; the antibonding eg* in MO theory corresponds to eg in CFT).
- A t<sub>2g</sub> to eg* transition (technically t<sub>2g</sub> to eg MO; the antibonding eg* in MO theory corresponds to eg in CFT)
- B A simple sigma bonding to sigma antibonding transition occurring within the ligand framework in general practice
- C A pi bonding to pi antibonding transition localised largely on the surrounding ligand atoms as frequently described
- D A deep core 1s to 2s electronic transition occurring within the central metal atom itself in most textbook accounts
Correct answer: A. t<sub>2g</sub> to eg* transition (technically t<sub>2g</sub> to eg MO; the antibonding eg* in MO theory corresponds to eg in CFT)
Explanation: In MO theory for octahedral complexes, the t<sub>2g</sub> MOs (non-bonding) and eg* MOs (antibonding, metal dx2-y2 and dz<sup>2</sup> character) are involved in the d-d transition responsible for colour.
The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).
Concept context
Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.