Exploring Au(i) involving halogen bonding with N-heterocyclic carbene Au(i) aryl complexes in crystalline media

Among the known types of non-covalent interactions with a Au(i) metal center, Au(i) involving halogen bonding (XB) remains a rare phenomenon that has not been studied systematically. Herein, using five N-heterocyclic carbene (NHC) Au(i) aryl complexes and two iodoperfluoroarenes as XB donors, we demonstrated that the XB involving the Au(i) metal center can be predictably obtained for neutral Au(i) complexes using the example of nine co-crystals. The presence of XB involving the Au(i) center was experimentally investigated by single-crystal X-ray diffraction and solid-state (13)C CP-MAS NMR methods, and their nature was elucidated through DFT calculations, followed by electron density, electrostatic potential, and orbital analyses. The obtained results revealed a connection between the structure and HOMO localization of Au(i) complexes as XB acceptors, and the geometrical, electronic, and spectroscopic features of XB interactions, as well as the supramolecular structure of the co-crystals.