Question

Prelab : 1. Which of the complexes is most likely to be a low-s pin complex? [M(H 2 O) x ] n+ or [M(CN) x ] n+ ?

2. Will Ti 4+ most likely be colored or colorless? Why?

3. Which of the compounds shown below can function as ligands? CH 4 , CH 3 NH 2 , CH 3 OH, CH 3 CH 3

4. How many d-electrons will Fe 3+ have?

5. Which complex of Mn 2+ will most likely be pale in color? It’s high-spin complex or low-spin complex? (First see how many d-electrons Mn 2+ has. Then, write out what the high-spin and low-spin d-orbital configuration will look like. Then decide the answer based on allowed and forbidden transitions).

Answer 1

1. Strong field ligand complexes are low spin complexes and weak filed ligand complexes are high spin complexes. From [M(H ₂O)_x ]ⁿ⁺ and [M(CN)_x ]ⁿ⁺ ; [M(CN)_x ]ⁿ⁺ is a strong field ligand complex, therefore it is most likely be a low spin complex.
2. Ti⁴⁺ is colorless. Because the electronic configuration of Ti⁴⁺ is 4s⁰3d⁰ (d-d transition is not possible, so no color is observed.)
3. The compounds shown below can function as ligands: CH₃-NH₂ , CH₃-OH. Because ligands can act as Lewis bases. Ligands have at least one donor atom with an electron pair used to form covalent bonds with the central atom.
4. Number of d-electrons present in Fe³⁺ is five. (4s⁰3d⁵)
5. Number of d-electrons present in Mn²⁺ is five. (4s⁰3d⁵). High spin electronic configuration is t_2g³ e_g². Low spin electronic configuration is t_2g⁴ e_g¹. Therefore high spin complex of Mn²⁺ will most likely be pale in color.