Textbook Question
For each of the following complexes, draw a crystal field energy-level diagram, assign the electrons to orbitals, and predict the number of unpaired electrons.
(a) [Pt(NH3)4]2+ (square planar)
24. Transition Metals and Coordination Compounds
Crystal Field Theory: Square Planar Complexes
Multiple Choice
Which of the following complexes will have the largest crystal field splitting energy?
A
[Co(NH3)6]2+
B
[Cr(NH3)3(H2O)3]2+
C
[ZnCl4]2–
D
[Ni(CN)4]2–
Verified step by step guidance1
Identify the ligands in each complex and their position in the spectrochemical series. Ligands higher in the series cause greater crystal field splitting. For example, CN⁻ is a strong field ligand, while Cl⁻ is a weak field ligand.
Consider the oxidation state and electron configuration of the central metal ion in each complex. The metal's electron configuration can affect the extent of splitting.
Evaluate the geometry of each complex. Octahedral complexes generally have larger crystal field splitting compared to tetrahedral complexes.
Compare the crystal field splitting energy (Δ) for each complex based on the ligand strength and geometry. Strong field ligands and octahedral geometry typically result in larger Δ.
Determine which complex has the largest Δ by considering the ligand strength and geometry. [Ni(CN)4]2–, with strong field CN⁻ ligands and a square planar geometry, will have a large crystal field splitting energy.
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