Calculate the number of unpaired electrons and LFSE of [PtCl6 ]–2 ion .

Calculate the number of unpaired electrons and LFSE of [PtCl₆ ]^–2 ion .

The IUPAC  name of the above complex ion is hexa chlorido platinum(Iv) ion. The oxidation number or oxidation state of  platinum in this complex ion is +4 .

Coordination number( C.N ) of platinum is 6 .

The valence shell electronic configuration  of Pt ⁺⁴ ion  : [Xe] 5d⁶ .  The arrangement of the complex ion is octahedral .

Ligand Cl ^–, which is a weak  field Ligand . In Pt ⁺⁴ , the principal quantum number increased from 3 < 4 <5 . Hence, the Ligand field splitting factor increases by 70% and also the charge on the central cation is high .

 Hence, Cl ^– ion , which is actually acts as a weak field Ligand but acts as a strong field Ligand . Consequently, the crystal field splitting energy is greater than pairing energy , that is, 10 Dq_o >  P. 

Now, under the influence of the octahedral crystal field, the five degenerate d-orbital’s  of Pt ⁺⁴  ion are splitted into two sets of energetically different orbital’s. 

These two sets are energetically lower t_2g orbital and energetically higher e_g orbital . Since 10 Dq_o >  P , the pairing of electrons occurred in the low energy t_2g orbital .

As there are six electrons  in the 5d⁶ degenerate orbital’s , so according to crystal field theory the preffered  arrangement  is t_2g⁶ e_g⁰ .

The crystal field splitting of degenerate d-orbital’s of Pt ⁺⁴  ion  under the influence of Cl ^– ligand are as follows,

Since Cl ^– ligand acts as a strong  field Ligand , so the complex [PtCl₆ ]^–2 ion should be low  spin complex  and from the above splitting diagram ,it is clear that the complex ion have no unpaired electron . 

That is ,the number of unpaired electron is zero(0).

Since the number the number of unpaired electron is zero , so the complex [PtCl₆ ]^–2 does not exhibit magnetic properties.

The Ligand field stabilization energy ( LFSE ) of the above complex ion is,

6x( -4 Dq_o ) + 0 x 6 Dq_o +3P 
= –24 Dq_o + 0 Dq_o +3P  
= – 24 Dq_o +3P .
Summary:
Calculate the number of unpaired electrons and LFSE of [PtCl6 ]–2 ion .
What is ligand field stabilization energy ?
Calculate  the LFSE of [ Fe ( H₂O)₆ ]⁺³ ion  . 

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