Geometries of ammonia complexes of Ni2, Pt2, and Zn2

The geometries of the ammonia complexes of Ni2, Pt2, and Zn2 can be determined by considering the electronic configuration and the number of valence electrons of these transition metal ions.

1. Nickel (Ni2)
Nickel is a transition metal with the electronic configuration [Ar] 3d8 4s2. In the Ni2+ ion, two electrons are removed from the 3d subshell, leaving behind an electronic configuration of [Ar] 3d8. Nickel can form coordination complexes with ammonia (NH3) as a ligand.

When nickel forms a complex with ammonia, it undergoes hybridization of its d orbitals to form complex orbitals. In the case of Ni2+, which has an electronic configuration of d8, the hybridization of the d orbitals results in the formation of six complex orbitals. These complex orbitals are then used to form bonds with the ligands (ammonia molecules).

The resulting geometry of the ammonia complex of Ni2 is octahedral because there are six ligands attached to the central nickel ion. The ammonia ligands occupy the six corners of an octahedron around the nickel ion.

2. Platinum (Pt2)
Platinum is another transition metal with the electronic configuration [Xe] 4f14 5d9 6s1. In the Pt2+ ion, two electrons are removed from the 5d subshell, leaving behind an electronic configuration of [Xe] 4f14 5d9. Platinum can also form coordination complexes with ammonia as a ligand.

Similar to nickel, platinum undergoes hybridization of its d orbitals to form complex orbitals. In the case of Pt2+, which has an electronic configuration of d9, the hybridization of the d orbitals results in the formation of six complex orbitals. These complex orbitals are used to form bonds with the ammonia ligands.

The resulting geometry of the ammonia complex of Pt2 is square planar because there are four ligands attached to the central platinum ion. The ammonia ligands occupy the four corners of a square plane around the platinum ion.

3. Zinc (Zn2)
Zinc is not a transition metal but can still form coordination complexes with ammonia. The electronic configuration of zinc is [Ar] 3d10 4s2. In the Zn2+ ion, two electrons are removed from the 4s subshell, leaving behind an electronic configuration of [Ar] 3d10.

Zinc does not have any d electrons available for hybridization. Therefore, it does not undergo any hybridization and retains its original electronic configuration. The resulting geometry of the ammonia complex of Zn2 is tetrahedral because there are four ligands attached to the central zinc ion. The ammonia ligands occupy the four corners of a tetrahedron around the zinc ion.

Summary
In summary, the geometries of the ammonia complexes of Ni2, Pt2, and Zn2 are:
- Ni2: Octahedral
- Pt2: Square planar
- Zn2: Tetrahedral