Question

A solution of [Ni(H2O)6]2+ is faint green and paramagnetic (μ = 2.90 BM), whereas a solution of [Ni(CN)4]2- is colorless and diamagnetic. (a) Draw the molecular geometry and the d-orbital energy level diagrams for each complex, showing the electronic occupancy of the d-orbitals. (b) Explain the differences in magnetism and color.

Answer 1

16 ligond Nicho), * = wilt = x® High spin (as Hyo is weak li eld Sy octahedral pairing does not → sp3t? Hybridization occer baramagnetic as it contains two unpaired High spin and the of electrons , Hence due to d-d transition, it is green coloured M= n(n+2 = 2 (2+8) = B = 2.90 BM ſ H20 727 i hyo 120 Hao Ni 1120 [Ni(CN),]2- = Ni 2+ = 18 (low spin) dsp? o Hybridization I Square planar - deya een strong filed ligand get pairing of é -CN- JL dxy - TL d22 IL TL dxz, dyz all ě are paired Hence d-d transition Hence colourless diamagnetic is spin forbidden -