In Ziesses salt C=C bond length is :
`"Note":{{:(C-C"bond length in enthance is 1.54Å"),(C=C"bond length in enthance is 1.34Å"),(C-=C"bond length in enthance is 1.20Å"):}}`

Options

A. `1.37Å`
B. `1.19Å`
C. `1.87Å`
D. `1.34Å`

Explanation

To determine the bond length of the C=C bond in Zeiss's salt (also known as G's salt), we need to analyze the effects of coordination with platinum on the ethylene (C2H4) ligand. Here’s a step-by-step solution:

### Step 1: Identify the Formula of Zeiss's Salt
The formula of Zeiss's salt is given as potassium platinum(II) chloride, K2[PtCl4], which contains the ethylene ligand (C2H4).

**Hint:** Look for the coordination compound's formula to understand the ligands involved.

### Step 2: Understand the Structure of Ethylene
Ethylene (C2H4) has a double bond between the two carbon atoms, with a bond length of 1.34 Å. Each carbon is also bonded to two hydrogen atoms.

**Hint:** Recall the typical bond lengths of single, double, and triple carbon-carbon bonds.

### Step 3: Recognize the Role of Ethylene as a Ligand
In this complex, ethylene acts as a π-ligand. π-ligands can participate in synergic bonding with the metal center (platinum in this case).

**Hint:** Identify the type of ligand and its bonding characteristics.

### Step 4: Explain Synergic Bonding
In synergic bonding, the metal (platinum) accepts electron pairs from the π-ligand (ethylene) and simultaneously donates electron pairs back to the ligand's antibonding orbitals. This interaction affects the bond order of the C=C bond.

**Hint:** Understand how synergic bonding influences bond order and bond length.

### Step 5: Analyze the Effect on Bond Length
The bond order is defined as half the difference between the number of bonding and antibonding electrons. When the metal donates electrons to the antibonding orbitals, the bond order decreases, which in turn increases the bond length.

In this case, the initial bond length of ethylene is 1.34 Å. Due to the synergic bonding with platinum, the bond length will increase slightly.

**Hint:** Remember that an increase in bond length corresponds to a decrease in bond order.

### Step 6: Conclusion
Given that the bond length of the C=C bond in ethylene is initially 1.34 Å, and due to the synergic bonding effect, the bond length in Zeiss's salt will be slightly more than 1.34 Å. The correct bond length after coordination is approximately 1.37 Å.

**Final Answer:** The bond length of the C=C bond in Zeiss's salt is approximately **1.37 Å**.