(i) Draw the geometrical isomers of complex [Pt(NH₃)₂Cl₂]

(ii) On the basis of crystal field theory, write the electronic configuration for d⁴ ion if .

(iii) Write the hybridization and magnetic behaviour of the complex [Ni(CO)₄].

(Atomic no of Ni = 28)

(i) Geometrical isomers of complex compounds are those which have same ligand adjacent(cis) or across(trans) from one another. [Pt(NH₃)₂Cl₂] complex exhibits cis and trans forms.

Trans-diamminedichloroplatinum(II)

Cis- diamminedichloroplatinum(II)

(ii) The condition given is crystal field splitting energy in an octahedral complex ( is less than the energy required to pair up the electrons (as pairing energy is high they will not pair up). This occurs under the influence of a weak field ligands as between t_2g and e_g is less and the electronic configuration will be for d⁴ will be t_2g³ and e_g¹ .

(iii) electronic configuration of Ni = [Ar]3d⁸4s²

CO is a strong field neutral ligand so pairing up of electrons takes place. As there is no charge on the complex, the oxidation state of nickel is zero(it does not lose any electrons but pairs up as shown below).

The 4 pairs of electrons donated by ligand occupy the 4s and 4p orbitals as 3d is completely filled. So, its hybridization is sp^3..

Since all the electrons are paired up it is diamagnetic in nature.