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Ch.21 - Transition Elements and Coordination Chemistry
McMurry - Chemistry 8th Edition
McMurry8th EditionChemistryISBN: 9781292336145Not the one you use?Change textbook
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 21.107
Chapter 21, Problem 21.107

Draw a crystal field energy-level diagram, assign the electrons to orbitals, and predict the number of unpaired electrons for each of the following.
(a) [Cu(en)3]2+
(b) [FeF6]2-
(c) [Co(en)3]3+ (low spin) 

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1
Identify the oxidation state and electron configuration of the central metal ion for each complex.
Determine the geometry and crystal field splitting pattern (octahedral or tetrahedral) for each complex.
For each complex, draw the crystal field energy-level diagram, showing the splitting of the d-orbitals.
Assign the electrons to the d-orbitals according to the electron configuration and the crystal field splitting pattern.
Count the number of unpaired electrons in the d-orbitals for each complex.

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Key Concepts

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

Crystal Field Theory

Crystal Field Theory (CFT) explains how the arrangement of ligands around a central metal ion affects the energy levels of its d-orbitals. In an octahedral field, for example, the d-orbitals split into two energy levels: the lower-energy t2g and the higher-energy eg orbitals. This splitting is crucial for determining the electronic configuration of transition metal complexes and predicting their magnetic properties.

Electron Configuration and Orbital Filling

The electron configuration of a transition metal complex is determined by the number of d-electrons and the ligand field strength. Electrons fill the lower energy orbitals first, following Hund's rule and the Pauli exclusion principle. Understanding how to assign electrons to the split d-orbitals based on the ligand type (strong or weak field) is essential for predicting the number of unpaired electrons in a complex.
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Magnetic Properties of Transition Metal Complexes

The magnetic properties of transition metal complexes are influenced by the presence of unpaired electrons. Complexes with unpaired electrons exhibit paramagnetism, while those with all paired electrons are diamagnetic. By analyzing the electron configuration derived from the crystal field energy-level diagram, one can predict whether a complex will be paramagnetic or diamagnetic, which is important for understanding its chemical behavior.
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Related Practice
Textbook Question

The amount of paramagnetism for a first-series transition metal complex is related approximately to its spin-only magnetic moment. The spin-only value of the magnetic moment in units of Bohr magnetons (BM) is given by sqrt(n(n + 2)), where n is the number of unpaired electrons. Calculate the spin-only value of the magnetic moment for the 2+ ions of the first-series transition metals (except Sc) in octahedral complexes with (a) weak-field ligands and (b) strong-field ligands. For which electron configurations can the magnetic moment distinguish between high-spin and low-spin electron configurations?

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Textbook Question

The oxalate ion is a bidentate ligand as indicated in Figure 21.8. Would you expect the carbonate ion to be a monodentate or bidentate ligand? Explain your reasoning.

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Textbook Question

Six isomers for a square planar palladium(II) complex that contains two Cl-and two SCN-ligands are shown below.


(a) Which structures are cis-trans isomers?

(b) Which structures are linkage isomers?

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Textbook Question

For each of the following complexes, describe the bonding using valence bond theory. Include orbital diagrams for the free metal ion and the metal ion in the complex. Indicate which hybrid orbitals the metal ion uses for bonding, and specify the number of unpaired electrons. 

(a) [AuCl4]2 (square planar)

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Textbook Question

Draw a crystal field energy-level diagram for the 3d orbitals of titanium in [Ti(H2O)6]3+]. Indicate the crystal field splitting, and explain why is [Ti(H2O)6]3+] colored.

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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?

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