Theoretical Study of Multi-Coordinated Xe(AuF)n (n = 2-4): Intriguing Bond-bending Isomerism

This work reports a theoretical study of a novel family of multi-coordinated noble gas (Ng) complexes, Xe(AuF)n (n = 2-4). Geometrical optimization at the LC-ωPBE-D3/def2TZVPP level locates two types of structures based on the bond-bending isomerism induced by an intramolecular competition between Xe-Au covalent bonding and Au···Au aurophilic interactions. They both comprise a center Xe atom serving as an electron donor binding to AuF moieties, but pronouncedly differ in the Au-Au distance and Au-Xe-Au bending angle. Comprehensive chemical bonding analysis undisputedly demonstrates that aurophilic interactions exist and affect the strength of Xe-Au bonds whose covalent nature is evident. By scanning the potential energy surface of Xe(AuF)2 with arbitrary one atom being substituted by its analogue, we found only Xe(AuF)2 and Xe(AuCl)2 feature bond-bending isomerism, due to the highly electronegative F/Cl atom inducing strongly covalent Xe-Au bond via electron donation-feedback mechanism. The present work predicts multi-coordinated Ng-metal complexes and demonstrates the bond-bending isomerism, which could be an interesting addition and call out more attentions to the research field of Ng chemistry.