An octahedral complex of Co ³⁺ is formed with ligands such that the crystal field splitting energy ( _o ) is greater than the pairing energy ( P ). The spin-only magnetic moment of this complex (in BM) is:

Step-by-step solution

Co has atomic number 27. Its electronic configuration is [ Ar ] 3d^7 4s^2 . For Co ³⁺ , the electronic configuration is [ Ar ] 3d^6 . Given that the complex is octahedral and _o > P , the ligands produce a strong field, leading to a low-spin complex. The 6 electrons will pair up in the lower energy t_ 2g orbitals, giving the configuration t_ 2g ^6 e_g^0 . Since there are no unpaired electrons ( n = 0 ), the spin-only magnetic moment is: = n(n+2) = 0(0+2) = 0 BM . Answer: 0