The correct answer is option 2. Synergic effect
Synergic Effect:
The synergic effect is a term used in coordination chemistry to describe the combined effect of both σ-bonding and π-bonding interactions between a metal (M) and a ligand (L). When a ligand forms both a σ-bond (metal to ligand, M → L) and a π-bond (ligand to metal, L → M) with the metal center, it results in an overall stronger metal-ligand bond compared to a complex where only a σ-bond is formed.
In the synergic effect, the π-bond formed by the donation of electron density from the ligand's π-orbital to the metal's vacant d-orbital reinforces the σ-bonding interaction, leading to increased stability of the metal-ligand complex. This combined effect strengthens the metal-ligand bond and influences various properties of the coordination complex.
Explanation of the Other Options:
(1) Chelate effect: The chelate effect refers to the enhanced stability of a metal complex that results from the formation of a cyclic structure (chelate ring) involving the metal ion and multiple donor atoms of the same ligand. Chelating ligands have two or more coordinating groups that can bind to the metal center.
(3) Crystal field effect: The crystal field effect refers to the interaction between the ligand's electron orbitals and the metal ion's d-orbitals, leading to the splitting of d-orbitals into different energy levels in a coordination complex. This results in the characteristic color of transition metal complexes and affects their magnetic properties.
(4) Electromeric effect: The electromeric effect is a term used in organic chemistry and refers to the movement of electrons in a sigma bond in response to the attack of an electrophile or nucleophile, leading to a temporary charge separation.
Since the provided statement specifically relates to the strengthening of the σ M → L bond due to the additional π M ← L bond, the correct answer is option (2) Synergic effect. |
