Certainly! Here is the answer to your question: --- ### **Trans Effect:** The **trans effect** is an effect observed in square planar complexes (especially of platinum(II)), where certain ligands can increase the rate of substitution of the ligand trans (opposite) to themselves. In other words, a ligand with a strong trans effect makes it easier for another ligand to replace the ligand opposite to it. **Order of trans effect (from strongest to weakest):** `CN⁻ > CO > NO₂⁻ > I⁻ > Br⁻ > Cl⁻ > py (pyridine) > NH₃ > H₂O` --- ### **Synthesis of [PtCl(py)(NH₃)Br] from [PtCl₄]²⁻:** #### **Step 1: Starting Material** - [PtCl₄]²⁻ (tetrachloroplatinate(II)) #### **Step 2: Substitution with NH₃** Add ammonia (NH₃) to substitute one Cl⁻ ligand. - **[PtCl₄]²⁻ + NH₃ → [PtCl₃(NH₃)]⁻ + Cl⁻** NH₃ will replace a Cl⁻. Since Cl⁻ and NH₃ both have weak trans effect, the substitution can occur at any position. #### **Step 3: Substitution with Pyridine (py)** Add pyridine (py) to substitute another Cl⁻ ligand. - **[PtCl₃(NH₃)]⁻ + py → [PtCl₂(py)(NH₃)] + Cl⁻** Py has a stronger trans effect than NH₃, so it prefers to go trans to NH₃. #### **Step 4: Substitution with Br⁻** Add Br⁻ to substitute the Cl⁻ ligand trans to py (because py has a stronger trans effect than Cl⁻ or NH₃). - **[PtCl₂(py)(NH₃)] + Br⁻ → [PtCl(py)(NH₃)Br] + Cl⁻** --- ### **Sequence of Reactions:** 1. **[PtCl₄]²⁻ + NH₃ → [PtCl₃(NH₃)]⁻ + Cl⁻** 2. **[PtCl₃(NH₃)]⁻ + py → [PtCl₂(py)(NH₃)] + Cl⁻** 3. **[PtCl₂(py)(NH₃)] + Br⁻ → [PtCl(py)(NH₃)Br] + Cl⁻** --- ### **Summary Table:** | Step | Reactant | Reagent | Product | |------|-------------------------------|-------------|-------------------------------| | 1 | [PtCl₄]²⁻ | NH₃ | [PtCl₃(NH₃)]⁻ | | 2 | [PtCl₃(NH₃)]⁻ | py | [PtCl₂(py)(NH₃)] | | 3 | [PtCl₂(py)(NH₃)] | Br⁻ | [PtCl(py)(NH₃)Br] | --- **Note:** The order of addition is crucial due to the trans effect. Adding py before Br⁻ ensures that Br⁻ will be placed trans to py, which is dictated by the stronger trans effect of pyridine compared to NH₃ or Cl⁻. --- If you would like a reaction scheme or structural diagrams, let me know!