Discuss the nature of bonding in metal carbonyls
Solution and Explanation
The metal-carbon bonds in metal carbonyls have both \(ÃÆ’\) and \(À\)characters. A \(ÃÆ’\) bond is formed when the carbonyl carbon donates a lone pair of electrons to the vacant orbital of the metal. A \(À\) bond is formed by the donation of a pair of electrons from the filled metal d orbital into the vacant anti-bonding \(À*\) orbital (also known as back bonding of the carbonyl group). The \(ÃÆ’\) bond strengthens the \(À\) bond and vice-versa. Thus, a synergic effect is created due to this metal-ligand bonding. This synergic effect strengthens the bond between CO and the metal.
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Concepts Used:
Bonding in Metal Carbonyls
The metal-carbon bond possesses both the σ and π character in a metal carbonyl. The synergic effect produced by the metal-ligand bond strengthens the bond between the carbonyl molecule and the metal. The types of bonding that exist in metal carbonyls are as follows:
Structure of Metal Carbonyls:
- Due to the donation of electrons by the carbonyl molecules to the vacant orbitals of the metal, a metal-carbon σ bond is formed.
- Due to the donation of a pair of electrons from a filled d orbital metal into the vacant anti bonding π orbital of carbonyl ligand, a metal-carbon π bond is formed.
Stability of Coordination Compounds:
They are found to dissociate in various solutions. The stability of a coordination compound in a solution mainly depends on the degree of association between the two species involved in the state of equilibrium. For the formation of the compound quantitatively the stability of any complex is given by the magnitude of the equilibrium constant. For instance,
A + 4B→ AB4