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: Identify that CN^-, CO, and NO^+ are 14-electron isoelectronic species (CN^- = 6+7+1 = 14; CO = 6+8 = 14; NO^+ = 7+8-1 = 14). Step 2: According to molecular orbital (MO) theory, any 14-electron diatomic species has a bond order of 3.0 with all electrons paired in the molecular orbitals. Step 3: Consequently, all three species are diamagnetic and possess a bond order of three, matching option (a).