Consider the following two carbonyl compounds
(i) `[Tc(CO)_(6)]^(+) and (ii)[Nb(CO)_(6)]^(-)`
Select incorrect statement(s) for given carbonyl compounds.

Options

A. `{Tc(CO)_(6)]^(+)` acts as reducing agent and `[Nb(CO)_(6)]^(-)` acts as oxidizing agent
B. `[Nb(CO)_(6)]^(-)` acts as reducing agent and `[Tc(CO)_(6)]^(+)` acts as oxidizing agent
C. `"Nb-C"` bond order in `[Nb(CO)_(6)]^(-)` is greater than in `{Tc(CO)_(6)]^(+)`
D. "CO" bond order is greater in `[Nb(CO)_(6)]^(-)` than in `[Tc(CO)_(6)]^(+)`

Answer

To solve the question regarding the carbonyl compounds \([Tc(CO)_6]^+\) and \([Nb(CO)_6]^-\), we need to analyze the statements related to their properties and behavior. Here is a step-by-step solution:

### Step 1: Determine the Effective Atomic Number (EAN)

1. **For \([Tc(CO)_6]^+\)**:
- Atomic number of Technetium (Tc) = 43
- Each CO contributes 2 electrons, so for 6 CO, total = \(6 \times 2 = 12\) electrons.
- Total electrons = \(43 + 12 = 55\)
- Since the charge is +1, we subtract 1 electron: \(55 - 1 = 54\)

2. **For \([Nb(CO)_6]^-\)**:
- Atomic number of Niobium (Nb) = 41
- Total electrons from 6 CO = \(6 \times 2 = 12\)
- Total electrons = \(41 + 12 = 53\)
- Since the charge is -1, we add 1 electron: \(53 + 1 = 54\)

### Step 2: Analyze the EAN Rule

Both compounds have an EAN of 54, which corresponds to the electronic configuration of the nearest noble gas (Krypton). According to the EAN rule, this indicates that both compounds are stable and do not act as strong oxidizing or reducing agents.

### Step 3: Evaluate the Reducing and Oxidizing Behavior

- **Statement 1**: \([Tc(CO)_6]^+\) acts as a reducing agent and \([Nb(CO)_6]^-\) acts as an oxidizing agent.
- This statement is incorrect because both complexes do not exhibit significant oxidizing or reducing behavior due to their stable EAN.

### Step 4: Compare Bond Orders

1. **Bond Order of \([Nb(CO)_6]^-\) vs. \([Tc(CO)_6]^+\)**:
- The bond order is influenced by the size of the metal ion and the extent of backbonding.
- Nb is smaller than Tc, which allows for greater backbonding with CO ligands. Thus, \([Nb(CO)_6]^-\) has a higher bond order than \([Tc(CO)_6]^+\).

2. **Statement 2**: The bond order in \([Nb(CO)_6]\) is greater than in \([Tc(CO)_6]^+\).
- This statement is correct.

### Step 5: Compare CO Bond Orders

- **Statement 3**: The CO bond order is greater in \([Nb(CO)_6]\) than in \([Tc(CO)_6]\).
- Since \([Nb(CO)_6]\) has a higher bond order due to better backbonding, the CO bond order in \([Nb(CO)_6]\) will be greater than in \([Tc(CO)_6]\).

### Conclusion

The incorrect statements regarding the given carbonyl compounds are:
- **Statement 1**: \([Tc(CO)_6]^+\) acts as a reducing agent and \([Nb(CO)_6]^-\) acts as an oxidizing agent.