The geometry of `[PtCI_(4)]^(2-)`is

Options

A. Tetrahedral
B. Square planar
C. Octahedral
D. Pyramidal

Answer

To determine the geometry of the complex ion \([PtCl_4]^{2-}\), we can follow these steps:

### Step 1: Identify the oxidation state of platinum
The complex \([PtCl_4]^{2-}\) consists of platinum and four chloride ions. Each chloride ion (Cl) has a charge of -1. Therefore, the total charge contributed by the four chloride ions is -4. Since the overall charge of the complex is -2, we can set up the following equation to find the oxidation state of platinum (Pt):

\[ \text{Charge of Pt} + \text{Charge from Cl} = \text{Total charge} \]
\[ \text{Charge of Pt} - 4 = -2 \]

Solving for the charge of Pt gives:
\[ \text{Charge of Pt} = -2 + 4 = +2 \]

Thus, the oxidation state of platinum in \([PtCl_4]^{2-}\) is +2.

### Step 2: Determine the coordination number
In the complex \([PtCl_4]^{2-}\), there are four chloride ligands coordinated to the platinum ion. Therefore, the coordination number is 4.

### Step 3: Identify the type of ligands
Chloride ions (Cl\(^-\)) are considered weak field ligands. Weak field ligands typically do not cause significant splitting of the d-orbitals in transition metals.

### Step 4: Determine the geometry based on coordination number and ligand strength
For a coordination number of 4, the possible geometries are tetrahedral and square planar. However, the geometry can be influenced by the oxidation state and the nature of the metal ion.

In the case of platinum(II) with a +2 oxidation state, it is known to favor a square planar geometry due to the larger size of the d-orbitals and the resulting greater splitting of the d-orbitals, even when coordinated with weak field ligands like Cl\(^-\).

### Conclusion
Thus, the geometry of the complex \([PtCl_4]^{2-}\) is **square planar**.

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