Which among the following is a paramagnetic complex?
(At No. of Mo=42, Pt=78)

  • Option 1)

    Mo(CO)_{6}

  • Option 2)

    \left [ Co(NH_{3})_{6} \right ]^{3}

  • Option 3)

    \left [ Pt(en)Cl_{2} \right ]

  • Option 4)

    \left [ CoBr_{4} \right ]^{2-}

 

Answers (1)
P Plabita

As we learnt in 

Magnetic Moments (spin only) -

\sqrt{n\left ( n+2 \right )} where n= number of unpaired electron.

- wherein

Number of unpaired e^{-} s and corresponding magnetic moments

\\1\rightarrow 1.7\\2\rightarrow 2.8\\3\rightarrow 3.9\\4\rightarrow 4.9\\5\rightarrow 5.9

Since Br^{-}  is a weak feild ligand, so electrons in Co^{2+} will not pair up.

\therefore the complex has 3 unpaired electrons leaving it paramagnetic in nature.

 

 


Option 1)

Mo(CO)_{6}

This is incorrect option

Option 2)

\left [ Co(NH_{3})_{6} \right ]^{3}

This is incorrect option

Option 3)

\left [ Pt(en)Cl_{2} \right ]

This is incorrect option

Option 4)

\left [ CoBr_{4} \right ]^{2-}

This is correct option

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