Question

State a reason for each of the following situations :
$CO$ is a stronger complexing reagent than $N{H}_3$.

Answer 1

$CO$ is a stronger Complexing reagent than $N{H}_3$ because of back bonding. In case of $CO$, It is a good Sigma donor and a pi acceptor. There exists a back bonding in $CO$ complexes which are a donation of electrons from the filled d orbital of metals to a pi molecular orbital of $CO$.