"Like-like" tetrel bonding interactions between Sn centres: a combined ab initio and CSD study

Area of Science:

• Inorganic Chemistry
• Supramolecular Chemistry
• Computational Chemistry

Background:

• Noncovalent interactions are crucial for supramolecular assembly and crystal engineering.
• Tetrel bonding, a type of noncovalent interaction, typically involves heavier p-block elements.
• The potential of tin (Sn) to participate in tetrel bonding, specifically SnSn interactions, remains underexplored.

Purpose of the Study:

• To investigate the ability of tin (Sn) to form 'like-like' tetrel bonding interactions.
• To analyze the prevalence and structural patterns of SnSn contacts in existing crystal structures.
• To quantify the strength of SnSn interactions and the influence of substituents on these bonds.

Main Methods:

• Searched the Cambridge Structural Database (CSD) for noncovalent SnSn contacts.
• Performed ab initio calculations using RI-MP2/def2-TZVP level of theory on model dimers.
• Employed wave function analysis and Bader's theory of 'atoms-in-molecules' (AIM).

Main Results:

• Noncovalent SnSn contacts are common in X-ray structures, with two predominant patterns identified.
• Calculated binding energies for SnSn interactions range from 2-13 kcal mol⁻¹, comparable to hydrogen bonds.
• Substituent effects on interaction energies were analyzed using Hammett plots, showing good correlations.
• AIM analysis confirmed a correlation between electron density at the bond critical point and interaction strength.

Conclusions:

• Tin (Sn) readily forms 'like-like' tetrel bonds, demonstrating significant binding energies.
• These SnSn interactions are relevant for supramolecular assemblies and can be exploited in crystal engineering.
• The study highlights SnSn interactions as an underexplored but valuable motif in inorganic structural chemistry.