Isolation of elusive gold-phosphane tellurides: From bonding to σ-hole dynamics

Tellurium, one of Earth’s rarest elements, plays a crucial role in electronic and materials applications, yet its coordination chemistry with metals remains underexplored. Although gold and tellurium coexist in nature, their chemical interactions and tellurium transfer processes between metals are poorly understood due to the instability of intermediates. Here, we report the synthesis of elusive gold(I) and gold(III) complexes featuring a terminal triisopropylphosphane telluride, representing snapshots of a phosphane-mediated tellurium transfer. In gold(I) species, this process is driven by intermolecular Au···Au interactions, leading to decomposition. This instability is overcome by using a sterically demanding N-heterocyclic carbene, enabling the isolation of the first gold(I) complex with a terminal (iPr)3PTe ligand. Spectroscopic and computational studies reveal unique bonding trends across the chalcogen series (O, S, Se, and Te) and demonstrate that gold coordination amplifies the tellurium σ-hole, enhancing chalcogen bond catalysis, with the cationic gold(I) complex as the most active catalyst.