Which of the following octahedral complexes has a spin-only magnetic moment of 2.83 BM and a Crystal Field Stabilization Energy (CFSE) of -1.2 _o (ignoring pairing energy)?

Step-by-step solution

A spin-only magnetic moment of 2.83 BM indicates the presence of n = 2 unpaired electrons, since = 2(2+2) = 2.828 BM. Let us evaluate the number of unpaired electrons ( n ) and CFSE for each complex: [Cr(H₂O)₆]³⁺ : Cr ³⁺ is 3d^3 . The configuration is t_ 2g ^3 . n = 3 CFSE = 3 (-0.4 _o) = -1.2 _o [Ni(H₂O)₆]²⁺ : Ni ²⁺ is 3d^8 . The configuration is t_ 2g ^6 e_g^2 . n = 2 CFSE = 6 (-0.4 _o) + 2 (0.6 _o) = -2.4 _o + 1.2 _o = -1.2 _o [Mn(CN)₆]³⁻ : Mn ³⁺ is 3d^4 . CN^- is a strong field ligand, so it forms a low-spin co