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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 21.86
Chapter 21, Problem 21.86

Which of the following complexes can exist as diastereoisomers?
 
(a) [Cr(NH3)2Cl4]-
(b) [Co(NH3)5Br]2+
(c) [MnCl2Br2]2- (tetrahedral)
(d) [Pt(NH3)2Br2]2-

Verified step by step guidance
1
Identify the type of isomerism: Diastereoisomers are non-mirror image stereoisomers, which can occur in coordination complexes with certain geometries.
Examine the geometry of each complex: Diastereoisomerism is possible in octahedral complexes with different ligands, but not in tetrahedral complexes.
Analyze complex (a) [Cr(NH_3)_2Cl_4]^-: This is an octahedral complex with two different types of ligands, which can lead to cis-trans isomerism, a form of diastereoisomerism.
Analyze complex (b) [Co(NH_3)_5Br]^2+: This is an octahedral complex but with only one type of ligand differing, which does not allow for diastereoisomerism.
Analyze complex (d) [Pt(NH_3)_2Br_2]^2-: This is a square planar complex, which can exhibit cis-trans isomerism, a type of diastereoisomerism.

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Key Concepts

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

Stereoisomerism

Stereoisomerism refers to the phenomenon where compounds have the same molecular formula and connectivity of atoms but differ in the spatial arrangement of those atoms. This can lead to different properties and reactivity. Diastereoisomers are a type of stereoisomer that are not mirror images of each other, which is crucial for understanding the behavior of coordination complexes.
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Coordination Complexes

Coordination complexes consist of a central metal atom bonded to surrounding ligands, which can be neutral molecules or ions. The geometry of these complexes, such as octahedral or tetrahedral, influences their stereochemistry and potential for isomerism. The arrangement of ligands around the metal center is key to determining whether diastereoisomers can exist.
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Ligand Types and Their Influence

Ligands can be classified as monodentate, bidentate, or polydentate based on the number of donor atoms they use to bind to the metal center. The type and arrangement of ligands affect the symmetry and possible isomeric forms of the complex. Understanding how different ligands interact with the metal is essential for predicting the existence of diastereoisomers in coordination compounds.
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Related Practice
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

Although Cl- is a weak-field ligand and CN- is a strong field ligand, [CrCl6]3- and [Cr(CN)6]3- exhibit approximately the same amount of paramagnetism. Explain.

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Textbook Question

What is the oxidation state of the metal in each of the complexes?

a. AgCl2–

b. [Cr(H2O)5Cl]2+

c. [Co(NCS)4]2–

d. [ZrF8]4–

e. [Fe(EDTA)(H2O)]–

89
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Textbook Question

The glycinate anion, gly-= NH2CH2CO2 -, bonds to metal ions through the N atom and one of the O atoms. Using to represent gly-, sketch the structures of the four stereoisomers of Co(gly)3.

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Textbook Question

Draw all possible diastereoisomers of [Cr(C2O4)2(H2O)2]-. Which can exist as a pair of enantiomers?

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Textbook Question

Predict the number of unpaired electrons for each of the following. 

(c) Zn2+

(d) Cr3+

86
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