Chapter 9, Problem 9.8E

(a)

Interpretation Introduction

Interpretation:

The type of ligands which are pi-acids in general has to be given.

Concept Introduction:

Pi-acid or Pi- acceptor:

Ligands having empty orbitals, which can interact with metal d-orbitals for the formation of $\text{π}$ -bond are called $\text{π}$-acceptor ligands.  This ligand possesses vacant $\text{π*}$-anti-bonding molecular orbitals or empty d- orbitals of metals along with filled $\text{σ}$-orbitals.  On bonding metal d-orbital donate its electron density to empty $\text{π}$-orbital of these ligands and this type of bonding is called $\text{π}$-backbonding.

(b)

Interpretation Introduction

Interpretation:

The type of ligands which are pi-base in general has to be given.

Concept Introduction:

Pi-base or Pi-donor:

In coordination chemistry, a pi-donor ligand is a kind of ligand that is capable with filled non-bonding orbital that overlap with metal-base orbitals.  If the ligand molecule has pi electrons in d-orbitals they are referred as pi-donor.