Metal Carbonyls (G & E)

1. Match the ligands with their electron count based on neutral atom method

NO (bent)

Alkene (sideways)

μ-X (X is halogen)

η4-C4H4

η5-C5H5

Submit

2. V(CO)₆ readily reacts with Na to give Na[V(CO)₆] because V(CO)₆ is an 18-electron complex

True

False

The given statement is false. V(CO)6 does not readily react with Na to give Na[V(CO)6]. V(CO)6 is not an 18-electron complex.

Explanation

The given statement is false. V(CO)6 does not readily react with Na to give Na[V(CO)6]. V(CO)6 is not an 18-electron complex.

3. Match the complexes with the number of M-M bonds present in them

Cp2ZrCl2

Fe2(CO)9

(μ-H)2[η5-Cp(NO)WH]2

[η5-CpMo(CO)2]2

Submit

4. [η⁵-CpM(CO)₃]₂ obeys 18 electron rule and has one M-M bond. M could be

Mn(I), Cr(0)

Cr(0), Fe(I)

Ti(-I), Fe

Ti (0), Fe

The complex [η5-CpM(CO)3]2 has a total of 18 valence electrons, which satisfies the 18 electron rule. Additionally, it has one M-M bond, indicating that the metal M is present in two oxidation states. The only combination of metal oxidation states that satisfies both of these conditions is Mn(I) and Cr(0). Therefore, Mn(I) and Cr(0) are the possible options for M in this complex.

Explanation

The complex [η5-CpM(CO)3]2 has a total of 18 valence electrons, which satisfies the 18 electron rule. Additionally, it has one M-M bond, indicating that the metal M is present in two oxidation states. The only combination of metal oxidation states that satisfies both of these conditions is Mn(I) and Cr(0). Therefore, Mn(I) and Cr(0) are the possible options for M in this complex.

5. The complex, [η⁴-C₄H₄)₂M₂(CO)₃] obeys 18 electron rule and there is a triple bond between the metal atoms. Identify M from first row transition series

Cr

Fe

Co

Ni

The complex, [(η4-C4H4)2M2(CO)3], obeys the 18 electron rule, which means that it has a total of 18 valence electrons. Since there is a triple bond between the metal atoms, each metal atom contributes 3 electrons to the complex. This means that the remaining 12 electrons must come from the ligands. In the given options, only Fe (iron) has an atomic number that allows for the formation of a complex with 18 valence electrons. Therefore, Fe is the correct answer.

Explanation

The complex, [(η4-C4H4)2M2(CO)3], obeys the 18 electron rule, which means that it has a total of 18 valence electrons. Since there is a triple bond between the metal atoms, each metal atom contributes 3 electrons to the complex. This means that the remaining 12 electrons must come from the ligands. In the given options, only Fe (iron) has an atomic number that allows for the formation of a complex with 18 valence electrons. Therefore, Fe is the correct answer.

6. The decreasing order of backbonding is

[Ti(CO)6]2-< [V(CO)6]- < [Cr(CO)6] < [Mn(CO)6]+ < [Ir(CO)6]3+

[V(CO)6]- < [Ti(CO)6]2-< [Cr(CO)6] < [Ir(CO)6]3+ < [Mn(CO)6]+

[Ir(CO)6]3+ < [Mn(CO)6]+ < [Cr(CO)6] < [V(CO)6]- < [Ti(CO)6]2-

[V(CO)6]- < [Ti(CO)6]2-< [Cr(CO)6] < [Mn(CO)6]+< [Ir(CO)6]3+

The correct answer is [Ir(CO)6]3+

Explanation

The correct answer is [Ir(CO)6]3+

7. In the linear complex, (CO) – M – (CO) group, one of the CO group is replaced by Et₃N. Choose the correct statement that is related to the above substitution reaction

υCO increases because Et3N is a pi-acid ligand

υCO decreases because Et3N is a pi-acid ligand

υCO increases because Et3N is not a pi-acid ligand

υCO decreases because Et3N is not a pi-acid ligand

The correct statement is that υCO decreases because Et3N is not a pi-acid ligand. This is because Et3N is a Lewis base and not a pi-acid ligand. In the given linear complex, the CO ligands are pi-acceptor ligands, meaning they accept electron density from the metal center. When one of the CO ligands is replaced by Et3N, which is not a pi-acid ligand, it does not have the ability to accept electron density from the metal center like the CO ligands do. Therefore, the overall electron density around the metal center decreases, leading to a decrease in υCO.

Explanation

The correct statement is that υCO decreases because Et3N is not a pi-acid ligand. This is because Et3N is a Lewis base and not a pi-acid ligand. In the given linear complex, the CO ligands are pi-acceptor ligands, meaning they accept electron density from the metal center. When one of the CO ligands is replaced by Et3N, which is not a pi-acid ligand, it does not have the ability to accept electron density from the metal center like the CO ligands do. Therefore, the overall electron density around the metal center decreases, leading to a decrease in υCO.

8. [η⁵-Cp₂Fe₂(CO)_³] is an 18 electron compound and shows single band at 1785 cm^-1. Choose the statement from the following which describes its correct structure

There are no bridging CO groups and the complex contains Fe-Fe double bond

There are no terminal CO groups and the complex contains Fe-Fe double bond

There are 2 terminal and 1 bridging CO groups and the complex contains Fe-Fe double bond

There are 1 terminal and 2 bridging CO groups and the complex contains Fe-Fe double bond

The presence of a single band at 1785 cm-1 indicates the absence of terminal CO groups. Additionally, the complex contains an Fe-Fe double bond.

Explanation

The presence of a single band at 1785 cm-1 indicates the absence of terminal CO groups. Additionally, the complex contains an Fe-Fe double bond.