The common features among the species `CN^-, CO` and `NO^+`

Options

A. bond order three and dimagnetic
B. Bond order three and weak field ligands
C. Paramagnetic and strong field ligands
D. Paramagnetic and `pi`-acceptor ligands

Answer

To determine the common features among the species CN^-, CO, and NO^+, we will analyze their electronic configurations, bond orders, and magnetic properties step by step.

### Step 1: Determine the Total Number of Electrons
1. **CN^-**:
- Carbon (C) has 6 electrons, and Nitrogen (N) has 7 electrons.
- CN^- has an additional electron due to the negative charge.
- Total electrons = 6 (C) + 7 (N) + 1 (extra electron) = 14 electrons.

2. **CO**:
- Carbon (C) has 6 electrons, and Oxygen (O) has 8 electrons.
- Total electrons = 6 (C) + 8 (O) = 14 electrons.

3. **NO^+**:
- Nitrogen (N) has 7 electrons, and Oxygen (O) has 8 electrons.
- NO^+ has lost one electron due to the positive charge.
- Total electrons = 7 (N) + 8 (O) - 1 (lost electron) = 14 electrons.

### Step 2: Write the General Electronic Configuration
For molecules with 14 electrons, the general electronic configuration can be represented as:
- 1s², 1s²*, 2s², 2s²*, 2p², 2p², 2p², 2p²*, where the asterisk (*) denotes anti-bonding orbitals.

### Step 3: Calculate the Bond Order
Bond order can be calculated using the formula:
\[ \text{Bond Order} = \frac{(\text{Number of bonding electrons}) - (\text{Number of anti-bonding electrons})}{2} \]

1. **Bonding Electrons**:
- From the configuration, there are 10 bonding electrons (2 from each of the 5 bonding orbitals).

2. **Anti-bonding Electrons**:
- There are 4 anti-bonding electrons (2 from each of the 2 anti-bonding orbitals).

3. **Bond Order Calculation**:
\[ \text{Bond Order} = \frac{10 - 4}{2} = \frac{6}{2} = 3 \]

### Step 4: Determine Magnetic Properties
- Since there are no unpaired electrons in the electronic configuration, all three species (CN^-, CO, NO^+) are **diamagnetic**.

### Conclusion
The common features among the species CN^-, CO, and NO^+ are:
- **Bond Order**: 3
- **Magnetic Property**: Diamagnetic

### Final Answer
The correct option is: **Bond order 3 and diamagnetic**.

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