Question
Among the following complexes, the one which shows zero crystal field stabilisation energy (CFSE) is
-
[Mn(H2O)6]3+
-
[Fe(H2O)6]3+
-
[Co(H2O)6]3+
-
[Co(H2O)]3+
Solution
B.
[Fe(H2O)6]3+
The CFSE for octahedral complex is given by
CFSE = [-0.4 t2g e- +0.6 ege-]
For Mn3+, [3d4]--> t2g3e1g
therefore,
CFSE = [-0.4 x 3 + 0.6 x1]
=-0.6
For Fe3+, [3d] --> t2g3e2g
CFSE = [(-0.4 x 3) + (0.6 x2)] = 0
For Co2+, [3d7] --> t2g5e2g
CFSE = [(-0.4 x 5) + (0.6 x2)] =-0.8
For Co3+, [3d6] ---> t2g4e2g
CFSE = [(-0.4 x4) + (0.6 x2)] = -0.4
For Fe3+, [3d] --> t2g3e2g
CFSE = [(-0.4 x 3) + (0.6 x2)] = 0
For Co2+, [3d7] --> t2g5e2g
CFSE = [(-0.4 x 5) + (0.6 x2)] =-0.8
For Co3+, [3d6] ---> t2g4e2g
CFSE = [(-0.4 x4) + (0.6 x2)] = -0.4
