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Ch.21 - Transition Elements and Coordination Chemistry
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 127
Chapter 21, Problem 127

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. (c) [Fe(H2O)6]2+ (high-spin) (d) [Fe(CN)6]4- (low-spin)

Verified step by step guidance
1
Step 1: Identify the oxidation state of the metal ion in each complex. For [Fe(H2O)_6]^{2+}, determine the oxidation state of Fe by considering the charge of the complex and the neutral charge of H2O ligands. Similarly, for [Fe(CN)_6]^{4-}, consider the charge of CN^- ligands.
Step 2: Determine the electron configuration of the free metal ion. For Fe^{2+} and Fe^{3+}, write the electron configuration based on the atomic number of iron (26) and the loss of electrons corresponding to the oxidation state.
Step 3: Use valence bond theory to describe the bonding in the complex. For [Fe(H2O)_6]^{2+}, identify the hybridization of the Fe^{2+} ion, considering it is a high-spin complex. For [Fe(CN)_6]^{4-}, identify the hybridization of the Fe^{3+} ion, considering it is a low-spin complex.
Step 4: Draw the orbital diagrams for the free metal ion and the metal ion in the complex. Show the distribution of electrons in the d orbitals for both high-spin and low-spin configurations, indicating any changes in electron pairing.
Step 5: Specify the number of unpaired electrons in each complex. For [Fe(H2O)_6]^{2+}, count the unpaired electrons in the high-spin configuration. For [Fe(CN)_6]^{4-}, count the unpaired electrons in the low-spin configuration.

Key Concepts

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

Valence Bond Theory

Valence Bond Theory (VBT) explains how atoms bond by overlapping their atomic orbitals to form localized bonds. In this theory, the hybridization of orbitals is crucial, as it describes how atomic orbitals mix to create new hybrid orbitals that can form bonds with other atoms. Understanding VBT is essential for analyzing the bonding in coordination complexes, as it helps predict the geometry and bond angles based on the types of hybrid orbitals involved.
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Valence Shell Electron Pair Repulsion Theory

Hybridization

Hybridization is the process of combining atomic orbitals to form new hybrid orbitals that are degenerate in energy. In coordination complexes, the metal ion can undergo hybridization to accommodate the ligands' electron pairs. For example, in [Fe(H2O)6]2+, the iron ion may use d2sp3 hybridization, while in [Fe(CN)6]4-, it may use dsp2 hybridization, reflecting the different geometries and electron configurations of the complexes.
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Spin States and Unpaired Electrons

The spin state of a complex refers to the arrangement of electrons in the d-orbitals of the metal ion, which can be either high-spin or low-spin. High-spin complexes have more unpaired electrons due to weaker field ligands, while low-spin complexes have fewer unpaired electrons due to stronger field ligands. Identifying the spin state is crucial for determining the magnetic properties of the complex and understanding the number of unpaired electrons, which influences the overall bonding and stability.
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Related Practice
Textbook Question

Give a valence bond description of the bonding in each of the following complexes. 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) [Ti(H2O)6]3+

Textbook Question

Give a valence bond description of the bonding in each of the following complexes. 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.

(c) [Fe(CN)6]3- (low-spin)

Textbook Question

Give a valence bond description of the bonding in each of the following complexes. 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.

(d) [MnCl6]32 (high-spin)

Textbook Question

There are three coordination compounds with the empirical

formula Co1NH3231NO223 in which all the nitrite ions

are bonded through the N atom. Two isomers have the

same molar mass but different nonzero dipole moments.

The third compound is a salt with singly charged ions and a molar mass twice that of the other compounds.

(a) Draw the structures of the isomeric compounds.