Problem 149 - A Complete Resource Book in Chemistry for JEE Main

Question

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

Step-by-Step Solution

Answer

The correct answer is (a) s, px, py, ext{d}_{x^2-y^2}.

Step 1: Understand Square Planar Geometry

Square planar complexes are coordination compounds that adopt a square-like arrangement around the central atom. This geometry is commonly observed in some transition metal complexes.

Step 2: Identify Suitable Hybridization

Square planar complexes typically involve dsp² hybridization because they require the central atom to utilize its d-orbitals in bonding to form a planar structure.

Step 3: Analyze the Given Options

The task is to determine which set of atomic orbitals can hybridize to form the dsp² hybridized orbitals. This requires identifying the orbitals used in dsp² hybridization: one s orbital, two p orbitals (px and py), and one d orbital ( ext{d}_{x^2-y^2}).

Step 4: Match Hybridization with Options

- Option (a) matches the dsp² hybridization with orbitals s, px, py, and ext{d}_{x^2-y^2}. - Options (b), (c), and (d) do not correspond to dsp² hybridization.

Key Concepts

dsp² Hybridization

Square planar complexes typically feature a unique type of bonding known as dsp² hybridization. This involves the mixing of atomic orbitals on a central atom to allow for the formation of a stable, coordinating structure. Specifically, dsp² hybridization involves the mixing of:

• one s orbital
• two p orbitals (namely\( p_x\) and\( p_y\))
• one d orbital (specifically the\( d_{x^2-y^2}\) orbital)

In this context, an unfilled d orbital from the central atom of the transition metal is essential. It helps accommodate electrons from the ligands, facilitating strong bonding between the central atom and the surrounding ligands. The stability achieved via dsp² hybridization is due to the specific alignment of these hybrid orbitals in a square plane. The geometry allows for maximum overlap with ligands, forming strong σ bonds.

Atomic Orbitals

Atomic orbitals are regions within an atom where there is a high probability of finding electrons. They come in different shapes, including s, p, and d shapes, which contribute to the electronic configuration and chemical behavior of atoms.

• s orbitals: These orbitals have spherical symmetry and can hold up to two electrons.
• p orbitals: They come in sets of three—\( p_x\), \( p_y\), and \( p_z\)—and have a dumbbell-like shape. Each can hold two electrons, contributing to the atom's directional bonding abilities.
• d orbitals: Five d orbitals are present, with varied complex shapes. In transition metals, these orbitals play a significant role in forming coordination compounds.

Understanding the characteristics and orientation of these orbitals is crucial for comprehending how atoms, particularly transition metals, form bonds and coordinate with other atoms or molecules.

Transition Metal Complexes

Transition metal complexes are fascinating structures where a central transition metal atom binds to surrounding molecules or ions, known as ligands. These complexes are integral in many chemical processes and applications, from catalysis to the color of compounds. Transition metals, due to their partially filled d orbitals, have distinct characteristics that enable them to form complexes. Some key aspects include:

• Variable Oxidation States: Transition metals often exhibit several oxidation states, allowing them to form various stable complexes.
• Coordination Number: This refers to the number of ligand atoms bonded to the central metal. For square planar complexes, the coordination number is typically four.
• Color and Magnetism: The presence of unpaired electrons in d orbitals can result in colorful complexes and affect magnetic properties.

These complexes are essential in diverse fields like biochemistry, where they can mimic the activity of natural metal-containing enzymes.