When degenerate d-orbitals of an isolated atom/ion come under influence of magnetic field of ligands — Coordination Compounds Chemistry Question
Question
When degenerate d-orbitals of an isolated atom/ion come under influence of magnetic field of ligands, the degeneracy is lost. The two set t2g (d_xy, d_yz, d_zx) and eg (d_z^2, d_x^2-y^2) are either stabilized or destabilized depending upon the nature of magnetic field. It can be expressed diagrammatically as : [SEE DIAGRAM] Value of CFSE depends upon nature of ligand and a spectrochemical series has been made experimentally, for tetrahedral complexes, \Delta is about 4/9 times to \Delta_o (CFSE for octahedral complex). This energy lies in visible region and i.e., why electronic transition are responsible for colour. Such transitions are not possible with d^0 and d^10 configuration.
💡 Solution & Explanation
Step 1: Ammonia (NH3) is a Lewis base that coordinates to copper ions through the lone pair of electrons on its nitrogen atom. Step 2: In acidic solutions, the high concentration of protons (H^+) causes ammonia to undergo protonation to form the ammonium ion (NH4^+). Step 3: Because NH4^+ lacks a lone pair of electrons, it cannot coordinate to Cu^2+ ions. Therefore, ammonia coordinates with protons instead of forming the complex, which corresponds to option (d).