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Ch.21 - Transition Elements and Coordination Chemistry
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 130
Chapter 21, Problem 130

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.

Verified step by step guidance
1
Identify the coordination number and geometry of the cobalt complex. Cobalt typically forms octahedral complexes with a coordination number of 6.
Determine the possible isomers. Since the nitrite ions are bonded through the nitrogen atom, consider linkage isomerism and geometric isomerism.
For the two isomers with nonzero dipole moments, consider cis and trans arrangements of the ligands around the cobalt center. In a cis isomer, similar ligands are adjacent, while in a trans isomer, they are opposite.
Draw the structures of the cis and trans isomers. In the cis isomer, place two nitrite ions adjacent to each other, and in the trans isomer, place them opposite each other.
For the third compound, which is a salt, consider that it has a molar mass twice that of the other compounds. This suggests it is a dimer or contains additional ions. Draw a structure that reflects this, possibly with two cobalt centers or additional counterions.

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Key Concepts

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

Coordination Compounds

Coordination compounds consist of a central metal atom or ion bonded to surrounding molecules or ions, known as ligands. The nature of these bonds can significantly influence the properties of the compound, including its geometry and reactivity. Understanding the coordination number and the types of ligands involved is essential for predicting the structure and behavior of these compounds.
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Isomerism in Coordination Compounds

Isomerism in coordination compounds occurs when two or more compounds have the same molecular formula but different arrangements of atoms. This can include structural isomers, where the connectivity of atoms differs, and stereoisomers, where the spatial arrangement of atoms varies. The presence of different isomers can lead to variations in physical properties, such as dipole moments, which are crucial for understanding the behavior of these compounds.
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Dipole Moment

The dipole moment is a measure of the separation of positive and negative charges in a molecule, indicating its polarity. It is influenced by the molecular geometry and the electronegativity of the atoms involved. In coordination compounds, differences in dipole moments between isomers can arise from variations in ligand arrangement, affecting their interactions with electric fields and solvents, which is important for predicting their chemical behavior.
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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.

(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)