Given below are four statements regarding the geometry and magnetic property of coordination complexes: (A) [ Ni ( CN )₄]²⁻ is square planar and diamagnetic. (B) [ Ni ( CO )₄] is tetrahedral and diamagnetic. (C) [ MnBr ₄]²⁻ is square planar and paramagnetic. (D) [ CoF ₆]³⁻ is octahedral and diamagnetic. How many of the above statements are correct?

Step-by-step solution

Statement (A): In [ Ni ( CN )₄]²⁻ , Ni is in +2 oxidation state ( 3d^8 ). Since CN ^- is a strong field ligand, pairing of electrons takes place, resulting in dsp^2 hybridization (square planar) and no unpaired electrons (diamagnetic). Thus, it is correct. Statement (B): In [ Ni ( CO )₄] , Ni is in 0 oxidation state ( 3d^8 4s^2 ). The strong field CO ligand causes the 4s electrons to pair up in the 3d orbitals, giving a 3d¹⁰ configuration. This results in sp^3 hybridization (tetrahedral) and no unpaired electrons (