Formation of C60-SnI4 adducts. Insights of the role of σ-hole and tetrel-bonding in the strength and interaction nature from DFT calculations

Abstract

C60-SnI4 cocrystals expose the ability of highly symmetric units to form chiral materials. Here, we explore the underlying characteristics accounting for the stabilization of the C60•••SnI4 interaction within the framework of relativistic dispersion-corrected DFT calculations. Our results explore different interaction modes ranging from a purely σ -bond to tetrel-bond for C60•••SnI4 denoting the larger contribution from London-type interaction being more relevant than the electrostatic character inherent to σ-hole interactions, owing to the presence of iodine atoms. The resulting aggregate is further evaluated owing to its structural flexibility given by different noncovalent interaction modes based on both σ -hole and tetrel-bonding characteristics of SnI4. Hence, it is proposed that C60-SnI4 cocrystals can be further modified under compression undergoing different phase transitions, leading to further exploration of crystal characteristics and versatility, which may be extended to other interesting π-systems. In addition, C60-EX4 (E = C, Si, Ge, Sn, Pb; X = Cl, Br, I) series are given, showing similar stabilizing characteristics, increasing towards heavier elements, denoting the C60-PbI4 cocrystal as a noteworthy case with stronger noncovalent interactions, which is here encouraged for further explorations.