Question

Synergic bonding involves:
A. The transference of electrons from ligands to metal
B. The transference of electrons from filled metal orbitals to anti-bonding orbitals of ligand
C. Both (A) and (B)
D. None of these

Answer 1

Hint: It is usually used in the context of organometallic chemistry where there is a transition metal centre and good pi-acceptor ligands. Now try to apply this concept in this question.

Complete step by step answer:

Synergistic bond stems from the fact that some bonds are self-strengthening in nature.In the chemistry of organometallics, the 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 must be pi-acceptor ligand.

Synergic bonding involves transference of electrons form ligands to metal and The transference of electrons from filled metal orbitals to anti-bonding orbitals of ligands.
It's a bond between a carbonyl group acting as a ligand and a metal.Synergic bonding means self strengthening bond.
It is formed by pi-acid ligands like CO. Pi-acid ligands are those which have a lone pair of electrons to donate to metal atom and an empty antibonding molecular orbital to back bond with the d-orbital electrons of metal atom

Hence, from all these statements we can conclude that option C is correct.

Note: The effect of synergistic bonds are as follows:
It strengthens the M-C bond while weakening the C-O bond.The phenomenon can clearly be observed by the increase in vibrational frequency of M-C bond in infrared to a point that is outside the normal range for IR spectrophotometer.
It also leads to shortening of the M-C-O bond length.