An octahedral complex with the formula [ M(H ₂ O )₆]²⁺ has a spin-only magnetic moment of approximately 3.87 BM . Identify the central metal ion M from the following options:

Step-by-step solution

The spin-only magnetic moment ( ) is given by the formula = n(n+2) BM , where n is the number of unpaired electrons. Given 3.87 BM , we can find n : n(n+2) = 3.87 n(n+2) 15 This gives n = 3 unpaired electrons. In the complex [ M(H ₂ O )₆]²⁺ , the metal ion M is in the +2 oxidation state. Since H ₂ O acts as a weak field ligand for most +2 metal ions, the complex will be high-spin. We evaluate the 3d electron configurations for the +2 ions of the given options in a high-spin octahedral field: Chromium ( Cr ²⁺ ): 3d^