Skip to main content
Ch.23 - Transition Metals and Coordination Chemistry
Chapter 23, Problem 22

Complete the exercises below. Which species are more likely to act as ligands? a. Positively charged ions or negatively charged ions? b. Neutral molecules that are polar or those that are nonpolar?

Verified step by step guidance
1
Step 1: Understand the concept of a ligand. A ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. Ligands can donate a pair of electrons to the metal atom.
Step 2: Consider the electron donation ability of charged ions. Negatively charged ions (anions) have extra electrons and are more likely to donate electron pairs compared to positively charged ions (cations), which are electron-deficient.
Step 3: Analyze the electron donation ability of neutral molecules. Polar molecules have regions of partial positive and negative charges, which can facilitate electron pair donation, making them more likely to act as ligands compared to nonpolar molecules, which have a more even distribution of electron density.
Step 4: Compare the likelihood of negatively charged ions and positively charged ions acting as ligands. Since ligands need to donate electrons, negatively charged ions are more likely to act as ligands due to their excess electrons.
Step 5: Compare the likelihood of polar and nonpolar neutral molecules acting as ligands. Polar molecules, with their uneven charge distribution, are more likely to donate electron pairs and act as ligands than nonpolar molecules.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ligands

Ligands are ions or molecules that can donate a pair of electrons to a central metal atom to form a coordination complex. They can be classified based on their charge and polarity, which significantly influences their ability to bond with metal ions. Understanding the nature of ligands is crucial for predicting their reactivity and stability in coordination chemistry.
Recommended video:
Guided course
01:12
Ligands Example

Charge of Ions

The charge of an ion plays a critical role in its ability to act as a ligand. Negatively charged ions (anions) are generally more effective ligands than positively charged ions (cations) because they can easily donate electron pairs to metal centers. This electron donation is essential for the formation of stable coordination complexes.
Recommended video:
Guided course
01:39
Polyatomic Ion Charges

Polarity of Molecules

The polarity of a molecule affects its solubility and interaction with metal ions. Polar molecules, which have a significant dipole moment, are more likely to interact with charged metal ions due to their ability to stabilize ionic interactions. In contrast, nonpolar molecules lack this ability, making them less effective as ligands in coordination chemistry.
Recommended video:
Guided course
02:38
Molecular Polarity