chemistry

Pnictogen bond

Pnictogen bond is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Pnictogen bond rather than just read about it. In short: In chemistry, a pnictogen bond (PnB) is a non-covalent interaction, occurring where there is a net attractive force between an electrophilic region on a 'donor' pnictogen atom (Pn) in a molecule, and a nucleophilic region on an 'acceptor' atom, which may be in the same or another molecule. Closely related to halogen and chalcogen bonding, pnictogen bonds are a form of non-covalent interaction which can be considered…

Key takeaways

Pnictogen bond belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Pnictogen bond to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Pnictogen bond from memory before moving on to harder problems.

Reference excerpt

In chemistry, a pnictogen bond (PnB) is a non-covalent interaction, occurring where there is a net attractive force between an electrophilic region on a 'donor' pnictogen atom (Pn) in a molecule, and a nucleophilic region on an 'acceptor' atom, which may be in the same or another molecule. Closely related to halogen and chalcogen bonding, pnictogen bonds are a form of non-covalent interaction which can be considered in terms of charge-transfer and electrostatic interactions.

Physical origins Pnictogen bonds typically demonstrate directionality, with the interaction forming either on a linear projection to the R–Pn bond (a σ-hole) or in a plane perpendicular to the three coplanar R–Pn bonds (a π-hole). In such cases, polarisation of the pnictogen atom by an electron-withdrawing substituent, results in an anisotropic electron distribution in the Pn atom affording a directional electropositive region, resulting in an attractive electrostatic interaction. As the polarisability of an atom increases upon descending the periodic table, pnictogen bond strengths typically increase upon descending pnictogen group, both as a result of increased poliarisation resulting in a greater electrostatic contribution to bonding, but also through increased dispersion interactions between the heavier PnB donor and the PnB acceptor atom. Contributions to pnictogen bonding interactions can also arise through charge transfer interactions, in which a lone pair on the pnictogen bond acceptor are donated into a σ*-orbital on the pnictogen atom. Despite the charge transfer interaction, pnictogen bond interactions are non-covalent interactions, with X···Y bond lengths shorter than the sum of the van der Waals radii, but significantly longer than the sum of the covalent radii.

Applications The directionality of σ-hole interactions, including PnB interactions, has resulted in their exploitation within the field of supramolecular chemistry, incorporating PnB donor systems into a range of systems exploiting the formation of weak intermolecular interactions for a range of applications.

Organocatalysis PnB donors have been demonstrated to be capable of functioning as Lewis acidic catalysts. PnB catalysis was first reported in 2018 when PnB interactions were demonstrated to be potent catalysts for the Reissert reaction. Given their intermediate position in the main group of the periodic table, PnB catalysis may be appealing due to a balance between steric repulsion and polarisability factors.

Anion recognition As for halogen and chalocogen bonding interactions, the σ-hole interactions in PnB hosts have been exploited for anion binding and recognition, with a report in 2022 exploiting a series of triaryl antinomy and bismuth receptors for binding of halide anions. The reported systems demonstrated selectivity for chloride from other halies and over the binding of oxoanions, in contrast to trends observed for hydrogen bonding systems, suggesting PnB interactions may have advantages in selective halide anion sensing over hydrogen bonding systems.

Transmembrane transport PnB systems have also been shown to be capable of transmembrane anion transport, in which lipophilic organopnictogen compounds bind an anion through PnB interactions, enabling transport. The redox activity of main group systems enables the tuning of transport, in which 'on/off' switchable behaviour is enabled between an inactive carrier and a reduced carrier. Park and Gabbaï have demonstrated such a system, in which reduction of an adjacent sulfonium enables the transmembrane transport of anions by an antimony transporter.

References

See also Sigma hole interactions Non-covalent interactions

Illustrations

Pnictogen bond: A pnictogen bonding anion receptor from Beer and co-workers. — A pnictogen bonding anion receptor from Beer and co-workers.

Worked examples

Example 1 — a first encounter with Pnictogen bond

Start with the simplest possible case. Write down what Pnictogen bond claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Pnictogen bond before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Pnictogen bond ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Pnictogen bond

In research: Pnictogen bond appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Pnictogen bond in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Pnictogen bond is common in secondary-school and first-year university syllabi. It links to neighbouring topics Chemical bonding, Intermolecular forces, so understanding it makes those chapters shorter.
In everyday life: Look for Pnictogen bond outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Pnictogen bond” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Pnictogen bond in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Pnictogen bond means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Pnictogen bond out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Pnictogen bond in simple terms?

Why does Pnictogen bond matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Pnictogen bond?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Pnictogen bond.