Question

Given that Cl^- stronger trans effect ligand than NH₃ Predict the results of the following ligand substitution reactions. Label your product as cis or trans

a) Pt(NH₃)₃ Cl + Cl^-=>

b) Pt(NH₃)Cl₃+Cl^-=>

Answer 1

Factors contributing to trans direction of substitution:

1) Trans influence: This is a thermodynamic factor. Some ligands weaken the M-L bond trans to them in the ground state and thus by facilitating the substitution. E.g. Strong σ- donors like H^-, I^-, Me^-, PR₃ etc., destabilize the M-L bond trans to themselves and thus by bringing the easy substitution of that ligand.

2) Trans effect: This is a kinetic factor and considered as true trans effect. It occurs by the stabilization of the transition state. E.g. The strong π-acceptors like NO⁺, C₂H₄, CO, CN^- etc., stabilize the transition state by accepting electron density that the incoming nucleophilic ligand donates to the metal through π-interaction.