A square planar complex is formed by hybridization of which atomic orbitals? (a) \(s, p x, p y, d x^{2}-y^{2}\) (b) s, px, py, dyz (c) s, px, py, dz (d) \(\mathrm{s}, \mathrm{px}, \mathrm{py}, \mathrm{dxy}\)

Coordination chemistry is a branch of inorganic chemistry that focuses on the study of compounds formed between metal ions and various ligands. Ligands are ions or molecules that can donate a pair of electrons to the metal ion, forming a coordination complex. These complexes have a central metal atom or ion, which is called the coordination center, surrounded by a number of ligands forming coordinate bonds.

The number of ligands attached to the central ion is known as the coordination number, which is a significant factor that influences the molecular geometry of the complex. For a square planar complex, the coordination number is typically four. The geometry of these complexes can greatly impact their chemical behavior and properties, such as reactivity, color, and magnetic properties. Understanding the principles of coordination chemistry helps in predicting and explaining the structure and bonding in these complexes, which is essential for applications across various fields such as catalysis, material science, and biochemistry.

Molecular geometry refers to the three-dimensional arrangement of atoms within a molecule. The shape of a molecule is a crucial aspect in determining its chemical and physical properties. In the case of coordination complexes, the geometry is influenced by the coordination number and the electronic repulsions between the ligands.

In a square planar complex, the geometry is characterized by four ligands that are symmetrically arranged around the central metal ion, at the corners of a square. This particular structure is associated with a coordination number of four. The square planar shape is often observed in complexes where the metal is in a d^8 electronic configuration and is particular to transition metals. Notably, this geometry can result in interesting chemical properties, such as differing reactivity compared to other geometries like tetrahedral or octahedral.

Orbital hybridization is a concept from quantum chemistry which provides an explanation for the bonding and geometry of molecules. It is the mixing of atomic orbitals to form new hybrid orbitals that can overlap effectively to form bonds with other atoms. These hybrid orbitals have different shapes and energies than the original atomic orbitals.

For the formation of a square planar complex, the central atom's orbitals undergo hybridization by combining one s orbital, two p orbitals, and one d orbital. In the context of square planar geometry, the consistent overlap of these orbitals with the ligands leads to the formation of a plane. The correct d orbital for this hybridization matching the molecular geometry is the dx2-y2 orbital because its lobes lie directly in the xy plane, which allows effective overlapping with the ligands in square planar complexes. This type of hybridization helps us comprehend how the shape of a molecule is related to the types of bonds that can form during the formation of a complex.