1)

 For the octahedral  complexes of Fe3+ in SCN- (thiocyanate- S) and in CN-  ligand environments, the difference between the spin only magnetic moments  in Bohr magnetons  (when approximated to the nearest  integer) is [ atomic number of Fe=26}


A) 3

B) 4

C) 1

D) 2

Answer:

Option B

Explanation:

 When S is donor atom of SCN- , it produces weak ligand field and forms high spin complex as 

 [Fe(SCN)6]3;Fe3+(3d5)=

732021477_c6.JPG

Spin           only       magnetic        moment

    (μs)=5(5+2)BM=35BM

 In case of CN- ligand , carbon  is the donor atom, it produces strong field and forms low spin  complex as

                         [Fe(CN)6]3:Fe3+(3d5)

732021725_c7.JPG

 Spin only magnetic moment   (μs)=1(1+2)BM

                           =3BM

  Hence, difference  in spin  only magnetic moment

      =353=4BM