Textbook Question
Complete the exercises below. Draw the crystal-field energy-level diagrams and show the placement of electrons for each of the following complexes:
a. [VCl6]3–,
b. [FeF6]3– (a high-spin complex),
24. Transition Metals and Coordination Compounds
Magnetic Properties of Complex Ions: Octahedral Complexes
Multiple Choice
Which of the following complex ions is/are diamagnetic in nature?
I. [Mn(Br4)]2– II. [V(NO2)4]4– III. [Zn(NH3)4]2+ IV. [Sc(H2O)6]3+
A
I, II, and IV
B
II and III
C
I and II
D
I, III, and IV
E
III and IV
Verified step by step guidance1
Step 1: Determine the oxidation state of the metal ion in each complex. Use the overall charge of the complex and the known charges of the ligands to find the metal's oxidation state. For example, in [Mn(Br_4)]^{2-}, Br is typically -1, so calculate Mn's oxidation state accordingly.
Step 2: Identify the electronic configuration of the metal ion in its oxidation state. Use the periodic table to find the number of d-electrons for the metal ion after accounting for its oxidation state.
Step 3: Determine the nature of the ligands (whether they are strong field or weak field ligands) to predict the crystal field splitting and whether the complex is high spin or low spin. For example, NH_3 and NO_2^- are generally strong field ligands causing pairing of electrons, while Br^- and H_2O are weak field ligands.
Step 4: Draw the crystal field splitting diagram for each complex and fill the d-electrons according to the high spin or low spin configuration. Count the number of unpaired electrons in each case.
Step 5: Identify which complexes have all electrons paired (no unpaired electrons). Complexes with no unpaired electrons are diamagnetic. Based on the electron configurations and ligand field strength, determine which complexes are diamagnetic.
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