Textbook Question
What is the oxidation state of the metal in each of the complexes?
a. [Ni(CN)5]3–
b. Ni(CO)4
c. [Co(en)2(H2O)Br]2+
d. [Cu(H2O)2(C2O4)2]2–
e. Co(NH3)3(NO2)3
Ch.21 - Transition Elements and Coordination Chemistry
McMurry8th EditionChemistryISBN: 9781292336145
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Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
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McMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 21.112
McMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 21.112Chapter 21, Problem 21.112
Draw a crystal field energy-level diagram for a square planar complex, and explain why square planar geometry is especially common for d8 complexes.
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Identify the metal ion and its oxidation state in the square planar complex. This will help determine the electron configuration and the number of d electrons present.
Understand that in a square planar complex, the ligands are positioned at the corners of a square in the xy-plane, leading to a specific splitting pattern of the d orbitals.
Recognize that the d orbitals split into different energy levels due to the ligand field. For a square planar complex, the order of increasing energy is typically: dz2, dxy, dyz = dxz, and dx2-y2.
Place the d electrons into the energy levels according to Hund's rule and the Pauli exclusion principle, starting from the lowest energy level. For a d8 complex, fill the lower energy orbitals first.
Explain that square planar geometry is common for d8 complexes because it allows for a stable electron configuration with lower energy, minimizing electron repulsion and maximizing ligand field stabilization energy.
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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 the d-orbitals. In a square planar geometry, the ligands are positioned in a way that causes specific splitting of the d-orbitals, leading to distinct energy levels. This theory helps predict the electronic structure and color of coordination complexes.
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Guided course
01:18
The study of ligand-metal interactions helped to form Ligand Field Theory which combines CFT with MO Theory.
d<sup>8</sup> Electron Configuration
The d<sup>8</sup> electron configuration refers to transition metal complexes that have eight electrons in their d-orbitals. This configuration is particularly stable in square planar complexes, as it allows for optimal pairing of electrons and minimizes electron-electron repulsion. Common examples include complexes of metals like nickel(II) and platinum(II).
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01:33Electron Configuration Example
Ligand Field Stabilization Energy (LFSE)
Ligand Field Stabilization Energy (LFSE) is the energy difference between the actual electronic configuration of a complex and the hypothetical configuration where all d-electrons are in the highest energy level. In square planar complexes, d<sup>8</sup> configurations can achieve a high LFSE due to effective pairing and lower energy arrangements, making this geometry energetically favorable.
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02:40Strong-Field Ligands result in a large Δ and Weak-Field Ligands result in a small Δ.
Related Practice
Textbook Question
Explain why [CoCl4]2- (blue) and [Co(H2O)6]2+ (pink) have different colors. Which complex has its absorption bands at longer wavelengths?
Textbook Question
Draw all possible diastereoisomers of [Cr(C2O4)2(H2O)2]-. Which can exist as a pair of enantiomers?
Textbook Question
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-
Textbook Question
Predict the number of unpaired electrons for each of the following.
(c) Zn2+
(d) Cr3+
Textbook Question
What is the general trend in standard potentials for the oxidation of first-series transition metals from Sc to Zn? What is the reason for the trend?