question_answer

A complex of a certain metal ion has a magnetic moment of 4.90 BM. Another complex of the same metal ion in the same oxidation state has a zero magnetic moment. The central metal ion could be which of the following?

A) \[C{{r}^{3+}}\]       

B)                    \[M{{n}^{3+}}\]                

C) \[F{{e}^{2+}}\]      

D)        \[C{{o}^{2+}}\]

Correct Answer: C

Solution :

[c] \[F{{e}^{2+}}:\] \[\mu =4.90\] B.M. corresponds to \[n=4\] which corresponds \[{{d}^{6}}\] configuration. In a weak field ligands, \[{{d}^{6}}\] configuration will have 4 unpaired electrons. In strong field ligands, \[{{d}^{6}}\]configuration will have no unpaired electrons with zero magnetic moment value. \[F{{e}^{2+}}\] have \[3{{d}^{6}}\] configuration. In weak field ligands: \[F{{e}^{2+}}:\]In strong field ligands: