Question

Which of the following is not expected to show paramanganetism ?

• A. $\left[Ni\right(H_{2}O){]}^{2+}$
• B. $Ni(CO{)}_4$
• C. $\left[Ni\right(N{H}_3{)}_4{]}^{2+}$
• D. $\left[Co\right(N{H}_3{)}_6{]}^{2+}$

Answer 1

The correct option is B $Ni(CO{)}_4$

In $\left[Ni\right(CO{)}_4]$, the valence shell electronic configuration of ground state Ni atom is $3d^{8}4s^2$. All of these 10 electrons are pushed into 3d orbitals and get paired up when strong field $CO$ ligands approach Ni atom. The empty 4s and three 4p orbitals undergo $s{p}^3$ hybridization and form bonds with four $CO$ ligands to give $\left[Ni\right(CO{)}_4]$ with tetrahedral geometry. Since all the electrons are paired, $\left[Ni\right(CO{)}_4]$ is diamagnetic.