Consider the follwing complex:
`[Co(NH_(3))_(5)CO_(3)]Br`
The coordiantion number, oxidation number, number of d-electrons and number of unpaired d-electrons of the metal are respectively:

Options

A. `6,3,6,0`
B. `7,1,6,4`
C. `7,2,7,1`
D. `6,2,7,3`

Answer

To solve the problem regarding the complex `[Co(NH₃)₅CO₃]Br`, we will follow these steps:

### Step 1: Determine the Coordination Number
The coordination number is the total number of ligand donor atoms that are bonded to the central metal atom. In this complex:

- The ligands are 5 NH₃ (ammonia) and 1 CO₃ (carbonate).
- Each NH₃ is a monodentate ligand, meaning it donates one pair of electrons.
- The CO₃ is also a monodentate ligand.

Thus, the coordination number is:
\[ \text{Coordination Number} = 5 \text{ (from NH₃)} + 1 \text{ (from CO₃)} = 6 \]

### Step 2: Determine the Oxidation Number of Cobalt
Let the oxidation number of cobalt be \( x \). The overall charge of the complex is neutral, and we have:

- The charge from bromide (Br) is -1.
- The ammonia (NH₃) is neutral, contributing 0.
- The carbonate (CO₃) has a charge of -2.

The equation can be set up as follows:
\[ x + 5(0) + (-2) + (-1) = 0 \]
\[ x - 2 - 1 = 0 \]
\[ x - 3 = 0 \]
Thus, the oxidation number of cobalt is:
\[ x = +3 \]

### Step 3: Determine the Number of d-Electrons
Cobalt (Co) has an atomic number of 27. The electron configuration of neutral cobalt is:
\[ \text{Co: } [Ar] 3d^7 4s^2 \]

When cobalt is in the +3 oxidation state, it loses 3 electrons (2 from 4s and 1 from 3d):
\[ \text{Co}^{3+}: [Ar] 3d^6 \]

Thus, the number of d-electrons is:
\[ \text{Number of d-electrons} = 6 \]

### Step 4: Determine the Number of Unpaired d-Electrons
Since NH₃ is a strong field ligand, it causes pairing of d-electrons in the presence of cobalt. In the case of Co³⁺ with 6 d-electrons, the electron configuration in the presence of a strong field ligand will be:
- All 6 d-electrons will be paired.

Thus, the number of unpaired d-electrons is:
\[ \text{Number of unpaired d-electrons} = 0 \]

### Summary of Results
- Coordination Number: 6
- Oxidation Number of Cobalt: +3
- Number of d-Electrons: 6
- Number of Unpaired d-Electrons: 0

### Final Answer
The coordination number, oxidation number, number of d-electrons, and number of unpaired d-electrons of the metal are respectively: **6, +3, 6, 0**.

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