`K_2 Pt Cl_6` is well known compound while corresponding Ni compound is not known?

Explanation

To understand why \( K_2PtCl_6 \) is a well-known compound while the corresponding nickel compound is not known, we need to analyze the oxidation states of the metals involved and the stability of those oxidation states.

### Step 1: Determine the oxidation state of Platinum in \( K_2PtCl_6 \)

1. **Identify the oxidation states of the components:**
- Potassium (K) has an oxidation state of +1. Since there are 2 potassium ions, their total contribution is \( 2 \times (+1) = +2 \).
- Chlorine (Cl) typically has an oxidation state of -1. With 6 chlorine ions, their total contribution is \( 6 \times (-1) = -6 \).

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