Which of the following outer octahedral complexes have same number of unpaired electrons? 1. ( [ MnCl ₆ ]³⁻ ) 2. ( [ FeF ₆ ]³⁻ ) 3. ( [ CoF ₆ ]³⁻ ) 4. ( [ Ni ( NH ₃ )₆ ]²⁺ )

Step-by-step solution

All four complexes given are outer orbital or high spin octahedral complexes. So, (d )-orbital electrons of central metal ions of the complexes remain unaffected by weak field ligands. So, (d )-configuration of free (M^ n+ ) and coordinated (M^ n+ ) will remain same. 1. 1. ( [ Mn Cl ₆ ]³⁻ Mn ³⁺ d^4, n=4 ) [ ( n= ) Number of unpaired electrons] 2. ( [ FeF ₆ ]³⁻ Fe ³⁺ d^5, n=5 ) 3. ( [ CoF ₆ ]³⁻ Co ³⁺ d^6, n=4 ) 4. ( [ Ni ( NH ₃ )₆ ]²⁺ Ni ²⁺ d^3, n=2 ) So, complexes 1 and 3 have same number of unpaired electrons ((n=