What is the magnetic moment (spin only) and hybridisation of the brown ring complex [Fe(H2O)5NO]SO4? — Coordination Compounds Chemistry Question

💡 Solution & Explanation

Step 1: In the brown ring complex [Fe(H2O)5NO]SO4, nitric oxide acts as a positive NO^+ ligand, making the iron center Fe^+ with a 3d^7 configuration. Step 2: Since H2O is a weak-field ligand, Fe^+ forms a high-spin octahedral complex (t_2g^5 e_g^2) with 3 unpaired electrons. Step 3: The spin-only magnetic moment is calculated as \mu = \sqrt{3(3+2)} = \sqrt{15} BM. Because it is a high-spin complex utilizing outer d-orbitals, the hybridization is sp^3d^2.