The hybridisation of `[CoF_(6)]^(3-) & [Co(C_(2)O_(4))_(3)]^(3-)` are :-

Options

A. Both `sp^(3)d^(2)`
B. Both `d^(2)sp^(3)`
C. `sp^(3)d^(2)` and `d^(2)sp^(3)`
D. `d^(2)sp^(3) and sp^(3)d^(2)`

Explanation

To determine the hybridization of the complexes \([CoF_6]^{3-}\) and \([Co(C_2O_4)_3]^{3-}\), we will analyze each complex step by step.

### Step 1: Determine the oxidation state of cobalt in both complexes.

1. **For \([CoF_6]^{3-}\)**:
- The overall charge of the complex is \(-3\).
- Fluorine (F) has a charge of \(-1\) and there are 6 fluorine atoms.
- Let the oxidation state of cobalt be \(x\).
- The equation is:
\[ x + 6(-1) = -3 \implies x - 6 = -3 \implies x = +3 \]

2. **For \([Co(C_2O_4)_3]^{3-}\)**:
- The overall charge of the complex is \(-3\).
- The oxalate ion \((C_2O_4)^{2-}\) has a charge of \(-2\) and there are 3 oxalate ions.
- Let the oxidation state of cobalt be \(y\).
- The equation is:
\[ y + 3(-2) = -3 \implies y - 6 = -3 \implies y = +3 \]

### Step 2: Determine the electronic configuration of cobalt in both complexes.

- Cobalt (Co) has an atomic number of 27. Its ground state electronic configuration is:
\[ [Ar] 3d^7 4s^2 \]
- For \(Co^{3+}\), we remove 3 electrons (2 from 4s and 1 from 3d):
\[ Co^{3+} \rightarrow [Ar] 3d^6 \]

### Step 3: Analyze the ligands and their field strength.

1. **For \([CoF_6]^{3-}\)**:
- The ligand is \(F^-\) (fluoride), which is a weak field ligand and does not cause pairing of electrons.
- The \(3d\) orbitals will remain unpaired.
- The configuration will be:
\[ 3d: \uparrow \uparrow \uparrow \uparrow \uparrow \uparrow \]
- Since there are 6 ligands, the hybridization involves one \(s\), three \(p\), and two \(d\) orbitals:
- **Hybridization**: \(sp^3d^2\)

2. **For \([Co(C_2O_4)_3]^{3-}\)**:
- The ligand is \(C_2O_4^{2-}\) (oxalate), which is a strong field ligand and causes pairing of electrons.
- The \(3d\) orbitals will have paired electrons:
- The configuration will be:
\[ 3d: \uparrow\downarrow \uparrow\downarrow \uparrow\downarrow \uparrow \]
- Since there are 3 oxalate ligands, each donating 2 electrons (total 6 electrons), the hybridization involves two \(d\), one \(s\), and three \(p\) orbitals:
- **Hybridization**: \(d^2sp^3\)

### Final Answer:
- The hybridization of \([CoF_6]^{3-}\) is \(sp^3d^2\).
- The hybridization of \([Co(C_2O_4)_3]^{3-}\) is \(d^2sp^3\).

### Summary:
- \([CoF_6]^{3-}\) → \(sp^3d^2\)
- \([Co(C_2O_4)_3]^{3-}\) → \(d^2sp^3\)