Problem 185 - A Complete Resource Book in Chemistry for JEE Main

Question

A square planar complex is formed by hybridization of the following atomic orbitals [2002] (a) \(s, p_{x}, p_{y}, p_{z}\) (b) \(s, p_{x}, p_{y}, p_{z}, d\) (c) \(\mathrm{d}_{\mathrm{x}}^{2}-\mathrm{y}^{2}, \mathrm{~s}, \mathrm{p}_{\mathrm{x}}, \mathrm{p}_{y}\) (d) \(s, p_{x}, p_{y}, p_{z}, d_{z^{2}}\)

Step-by-Step Solution

Answer

The correct hybridization for a square planar complex is (c) dₓ²₋ᵧ², s, pₓ, pᵧ.

Step 1: Understanding square planar complexes

Square planar complexes are typically seen in coordination chemistry involving transition metals. The geometry involves four ligands symmetrically arranged around a central metal atom, all lying in the same plane.

Step 2: Hybridization concept

To form a square planar complex, the central metal atom undergoes hybridization to accommodate the ligands. The hybridization must involve orbitals that can form planar structures.

Step 3: Identify hybridization type

In square planar complexes, the typical hybridization is dsp², where one d-orbital, one s-orbital, and two p-orbitals form the hybrid orbitals that create the plane.

Step 4: Check given options

Evaluate each provided option to determine which orbitals are involved in dsp² hybridization.

Step 5: Analysis of options

- (a) s, pₓ, pᵧ, pₓ do not involve d-orbitals and form tetrahedral (sp³) hybridization. - (b) s, pₓ, pᵧ, pₓ, d indicates potential dsp³ (trigonal bipyramidal) hybridization. - (c) dₓ²₋ᵧ², s, pₓ, pᵧ is dsp², forming a square planar complex. - (d) s, pₓ, pᵧ, pₓ, dₓ² do not match typical square planar hybridization.

Step 6: Conclusion on correct option

The correct option is (c) \(d_{x^2-y^2}, s, p_x, p_y\), where dsp² hybridization occurs, typical for square planar complexes.

Key Concepts

Square Planar Complexes

Square planar complexes are a fascinating structure in coordination chemistry, mainly involving transition metals. The distinctive geometry of these complexes features four ligands symmetrically arranged around a central metal atom, with all components lying in a single plane. This arrangement gives the complex its name – 'square planar' – because the ligands form a square when viewed in projection onto the plane.

This type of structure is not just aesthetically pleasing but also carries specific electronic properties that make it interesting for chemists. Some of the key characteristics include:

• The planar nature of the complex allows for certain symmetry operations, giving it a unique set of symmetries compared to other geometries like tetrahedral or octahedral complexes.
• Square planar complexes often have a specific electron count and are prevalent for d8 configuration transition metals, such as Nickel(II), Palladium(II), and Platinum(II).

Square planar complexes are important in various applications, including catalysis and materials science, due to their unique properties and stability.

dsp² Hybridization

Hybridization is a process where atomic orbitals mix to form new hybrid orbitals suitable for pairing with other atoms. In the context of square planar complexes, the hybridization that takes place is known as dsp². This process involves the mixing of one d-orbital, one s-orbital, and two p-orbitals belonging to the central metal atom.

The specific d-orbital used in dsp² hybridization is typically the \(d_{x^2-y^2}\), which allows for optimal overlap with the p_x and p_y orbitals. The resulting dsp² hybrid orbitals project in a square planar orientation, perfectly fitting the geometry of the complex.

Here are some points to help you understand dsp² hybridization better:

• The involvement of the d_{x^2-y^2} orbital is crucial because it lies in the same plane as the p_x and p_y orbitals, allowing for effective overlapping with ligands.
• This type of hybridization characterizes specific transition metal ions, especially those that exhibit low-spin states due to strong-field ligands.
• The resulting geometry from dsp² hybridization makes it energetically favorable for certain electronic configurations, typically being more stable because of minimized ligand repulsion.

Transition Metal Complexes

Transition metal complexes, often a major topic in coordination chemistry, consist of a central transition metal ion bound to surrounding molecules or ions, known as ligands. These complexes are fundamental in numerous chemical processes and applications due to their variable oxidation states and ability to form stable structures.

Some key features of transition metal complexes include:

• The ability to form a variety of complex geometries, such as tetrahedral, octahedral, and square planar, depending on the metal and ligands.
• Transition metal complexes can exhibit unique magnetic and spectral properties, which are exploited in various industrial and scientific applications, such as in catalysts and biological systems.
• The presence of d-orbitals in transition metals allows them to participate in different types of chemical bonding, contributing to the diversity of possible complexes.

Overall, transition metal complexes are a cornerstone in both theoretical and applied chemistry, offering a wide range of behaviors and uses that extend from small-scale laboratory reactions to large-scale industrial processes.