How many unpaired electrons does [Fe(bpy)3]2+ have?

To determine the number of unpaired electrons in [Fe(bpy)3]2+, we need to know the oxidation state of Fe and the electron configuration.

1. The oxidation state of Fe in [Fe(bpy)3]2+ is +2 because the overall charge of the complex is +2 and the ligands (bpy) are neutral.

2. The electron configuration of Fe is [Ar] 3d6 4s2. When Fe loses two electrons to become Fe2+, it loses the 4s electrons first, so the electron configuration of Fe2+ is [Ar] 3d6.

3. The 3d6 configuration can be split into t2g and eg sets in an octahedral field. The splitting of d orbitals is due to the ligand field created by the ligands surrounding the metal ion. In this case, the ligand is bipyridine (bpy), which is a strong field ligand and causes a large splitting of the d orbitals.

4. According to the Crystal Field Theory, the electrons will fill the lower energy t2g orbitals first. So, the 6 electrons in the 3d orbitals of Fe2+ will fill the t2g orbitals completely (with 6 electrons) and the eg orbitals will be empty.

5. Therefore, there are no unpaired electrons in [Fe(bpy)3]2+ because all the electrons are paired in the t2g orbitals.