Ch.21 - Transition Elements and Coordination Chemistry

McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook

McMurry 8th Edition

Ch.21 - Transition Elements and Coordination Chemistry

Problem 21.120

Chapter 21, Problem 21.120

Look at the colors of the isomeric complexes in Figure 21.12, and predict which is the stronger field ligand, nitro (-NO₂) of nitrito (-ONO). Explain.

Verified step by step guidance

Step 1: Recall that the color of a complex is complementary to the color absorbed by the complex. This is due to the fact that when white light (which contains all colors) shines on the complex, the complex absorbs a certain color and the remaining colors are what we see.

Step 2: The color absorbed by the complex corresponds to a certain energy, which is the energy difference between the ground state and the excited state of the d-electrons in the metal ion. This energy difference is influenced by the field strength of the ligands: stronger field ligands cause a larger energy difference, which corresponds to a shorter wavelength (and thus a color towards the violet end of the spectrum).

Step 3: Look at the colors of the isomeric complexes in Figure 21.12. The complex with the color towards the red end of the spectrum is the one that absorbs a color towards the violet end, and thus has a stronger field ligand.

Step 4: Identify which of the isomers has the color towards the red end of the spectrum. This is the isomer with the stronger field ligand.

Step 5: Therefore, if the isomer with the nitro (-NO2) ligand is towards the red end of the spectrum, then nitro is the stronger field ligand. If the isomer with the nitrito (-ONO) ligand is towards the red end of the spectrum, then nitrito is the stronger field ligand.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Was this helpful?

Key Concepts

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

Ligand Field Theory

Ligand Field Theory explains how the presence of ligands around a central metal ion affects the energy levels of the d-orbitals. Strong field ligands cause a larger splitting of these d-orbitals, leading to greater stabilization of low-energy states. This theory is crucial for understanding the color and magnetic properties of coordination complexes.

Crystal Field Splitting

Crystal Field Splitting refers to the energy difference between the split d-orbitals in a transition metal complex due to the electrostatic interactions between the metal ion and surrounding ligands. The extent of this splitting is influenced by the nature of the ligands, with strong field ligands causing larger splits, which can affect the color observed in the complex.

Field Strength of Ligands

The field strength of ligands is a measure of their ability to split the d-orbitals of a metal ion. Ligands are classified as strong or weak field based on their ability to cause this splitting. Nitro (-NO2) is generally considered a stronger field ligand than nitrito (-ONO), leading to greater d-orbital splitting and different electronic transitions, which can be observed as distinct colors in the complexes.

Recommended video:

Guided course

02:40

Strong-Field Ligands result in a large Δ and Weak-Field Ligands result in a small Δ.

Related Practice

Textbook Question

Draw the structures of all possible diastereoisomers of an octahedral complex with the formula MA₂B₂C₂. Which of the diastereoisomers, if any, can exist as enantiomers?

views

Textbook Question

What is the electron configuration of Co²⁺ and how many unpaired electrons are in the free transition metal ion?

(a) [Ar]3d⁵4s²; 5 unpaired electrons

(b) [Ar]3d⁵4s²; 1 unpaired electron

(d) [Ar]3d⁷; 1 unpaired electron

views

Textbook Question

The [Cr(H₂O)₆]³⁺ ion is violet, and [Cr(CN)₆]^3- is yellow. Explain this difference using crystal field theory. Use the colors to order H₂O and CN^- in the spectrochemical series.

137

views

Textbook Question

Based on the wavelength of maximum absorption of the cobalt complexes, arrange the following ligands in a spectrochemical series from weakest-field to strongest-field ligand.

(a) Cl^- < NCS^- < H₂O < NH₃

(b) Cl^- < NCS^- < H₂O < NH₃

(d) Cl^- < H₂O < NCS^- < NH₃

105

views

Textbook Question

Based on effective nuclear charge (Z_eff), which ion is the strongest oxidizing agent?

(a) Cu²⁺

(b) Ni²⁺

(d) Mn²⁺

105

views