Question

The number of complexes from the following with no electrons in the t$_{2g}$ orbital is _______.
TiCl$_4$, [MnO$_4$]$^{-}$, [FeO$_4$]$^{2-}$, [FeCl$_4$]$^{-}$, [CoCl$_4$]$^{2-}$

• A. 3
• B. 1
• C. 4
• D. 2

Answer 1

The Correct Option is A

To determine the number of complexes with no electrons in the \(t_2\) orbital, analyze each complex and its oxidation state, electronic configuration, and crystal field splitting.
Step 1: Analyze each complex
1.\(\text{TiCl}_4\):
- Oxidation state of Ti: \(+4 \, (\text{Ti}^{4+})\).  
- Electronic configuration of \(\text{Ti}^{4+}\): \(3d^0\).  
- No electrons in \(t_2\) orbitals.

2.\([\text{MnO}_4]^-\):  
- Oxidation state of Mn: \(+7 \, (\text{Mn}^{7+})\).  
- Electronic configuration of \(\text{Mn}^{7+}\): \(3d^0\).  
- No electrons in \(t_2\) orbitals.

3.\([\text{FeO}_4]^{2-}\):  
- Oxidation state of Fe: \(+6 \, (\text{Fe}^{6+})\).  
- Electronic configuration of \(\text{Fe}^{6+}\): \(3d^0\).  
- No electrons in \(t_2\) orbitals.
4.\([\text{FeCl}_4]^-\): 
- Oxidation state of Fe: \(+2 \, (\text{Fe}^{2+})\).  
- Electronic configuration of \(\text{Fe}^{2+}\): \(3d^6\).  
- \(t_2\) orbitals are populated with electrons (\(t_2^3e^3\)).
5.\([\text{CoCl}_4]^{2-}\):
- Oxidation state of Co: \(+2 \, (\text{Co}^{2+})\).  
- Electronic configuration of \(\text{Co}^{2+}\): \(3d^7\).  
- \(t_2\) orbitals are populated with electrons (\(t_2^4e^3\)).
Step 2: Count complexes with no \(t_2\) electrons 
- \(\text{TiCl}_4\), \([\text{MnO}_4]^-\), and \([\text{FeO}_4]^{2-}\) have no electrons in \(t_2\) orbitals.  
- \([\text{FeCl}_4]^-\) and \([\text{CoCl}_4]^{2-}\) have electrons in \(t_2\) orbitals.
Conclusion:
The number of complexes with no electrons in the \(t_2\) orbital is:  
\[3 \, (\text{TiCl}_4, \, [\text{MnO}_4]^-, \, [\text{FeO}_4]^{2-}).\]
Final Answer: (1).