Question

Write short notes on synergic bonding.

Answer 1

Hint: We must know that It is usually used in the context of organometallic chemistry where there is a transition metal center and good pi-acceptor ligands.

Complete step by step answer:
- The back donation reinforces the sigma bond and vice versa. This type of bonding has been called synergic bonding.
- Pi back bonding is very common in organometallic chemistry, where transition elements form coordinate covalent bonds with polyatomic ligands (examples of which include carbon monoxide and ethylene).
- Reason: This effect is observed when a pi-back donation of electron density occurs from an atomic orbital of one atom to the antibonding pi-orbital of another. The antibonding pi-orbital of a pi-acceptor ligand.
The interaction involved in the formation of a metal-carbonyl bond:

> Firstly donation of electrons from the ligand to an empty orbital on the metal which gives the typical ligand-metal interaction.
> A second interaction can occur if the metal has filled d orbitals. The electrons are donated from the filled d orbitals on the metal to an empty orbital of the ligand.
Together, these two interactions make up synergic bonding.
> Effects of synergistic bonds are:
(1) It strengthens the M-C bond while weakening the C-O bond.
(2) It also leads to a shortening of the M-C-O bond length.

Note: Synergistic bonds in organ-metallic chemistry are affected by various factors:
(1) Charge on the metal - To increase the strength of the synergic bonds, the central metal atom in the coordination complex should be electron rich.
(2) Contribution of other ligands on the metal center - Electron donating ligands increase the back-bonding process while the electron-withdrawing reduces the back-bonding process.