Square tetravalent chalcogen bonds in dimeric aggregates: a joint crystallographic survey and theoretical study

Abstract

Chalcogen bonds (ChBs) involving hypervalent chalcogen atoms have been the target of several recent crystallographic and theoretical studies. In this study, we first gathered a large number of crystal structures containing a four-membered synthon with double tetravalent Ch⋯O contacts were initially gathered from the Cambridge Structural Database. Then, a series of dimeric complexes of tetravalent chalcogenoxide species were selected to model such square interactions found in the crystals. In addition, atoms in molecules, noncovalent interaction index, natural bond orbital, and energy decomposition analyses were also employed to characterize these interactions. Square tetravalent ChBs show primary electrostatic character and become stronger with increasing atomic polarizability (S < Se < Te), similar to conventional divalent ChBs. In general, strong electron-withdrawing groups have a stronger effect on the σ-hole intensity of the chalcogen atoms than the basicity of the interacting O atoms, leading to enhanced tetravalent ChB interactions. We hope that the results reported herein will promote the application of hypervalent ChBs in crystal engineering and materials design.