Question

Among nickel (IV) and platinum (IV) compounds, which are more stable?

Answer 1

1. Platinum (IV) compounds are more stable than nickel (IV) compounds.
2. Stability is explained by ionisation enthalpies: the total energy needed to form Pt(IV) is less than for Ni(IV).
3. The sum of the first four ionisation enthalpies for Pt (IV) is lower (9.36 × 10³ kJ/mol) than that for Ni (IV) (11.29 × 10³ kJ/mol).
4. Hence, Pt(IV) compounds require less energy to form and are thermodynamically more stable.
5. Example: K₂PtCl₆ is a known Pt(IV) compound, whereas the corresponding Ni(IV) compound is not known.