Beyond hydrogen bonding: new definitions for secondary bonding interactions to end confusion

Proposals for the new definition of the tetrel bond will be available for community review in 2025, according to International Union of Pure and Applied Chemistry’s (Iupac) committee chair Giuseppe Resnati. The announcement follows the release of the pnictogen bond recommendations earlier this year as part of a 20-year mission to formally clarify the terminology around secondary bonding interactions after decades of confusion and misuse.

As a fundamentally non-visual discipline, chemistry needs clear and well-defined nomenclature to provide a reliable and meaningful way to convey for researchers to convey their findings to others. While the hydrogen bond is universally recognised by the chemistry community, its more obscure relatives – the halogen, pnictogen and tetrel bonds – are often overlooked, either misnamed or misclassified as other types of interaction. Over the last several decades, this widespread misuse of terminology created a disjointed and inconsistent base of knowledge within the literature which, in 2004, Iupac decided to tackle head-on.