Well-Defined Dinuclear Gold Complexes for Preorganization-Induced Selective Dual Gold Catalysis

The synthesis, reactivity, and potential of well‐defined dinuclear gold complexes as precursors for dual gold catalysis are explored. Using the preorganizing abilities of the ditopic PNHPiPr (LH) ligand, dinuclear AuI–AuI complex 1 and mixed‐valent AuI–AuIII complex 2 provide access to structurally characterized chlorido‐bridged cationic species 3 and 4 upon halide ion. For 2, this transformation involves unprecedented two‐electron oxidation of the redox‐active ligand, generating a highly rigidified environment for the Au2 core. Facile reaction with phenylacetylene affords the σ,π‐activated phenylacetylide complex 5. When applied in the dual gold heterocycloaddition of a urea‐functionalized alkyne, well‐defined precatalyst 3 provides high regioselectivities for the anti‐Markovnikov product, even at low catalyst loadings, and outperforms common mononuclear AuI systems. This proof‐of‐concept demonstrates the benefit of preorganization of two gold centers to enforce selective non‐classical σ,π‐activation with bifunctional substrates. Worth its weight in gold: Coordination of gold(I) to a rigid bis(o‐tolylamino)diphosphine ligand allows for versatile chemistry, including the isolation of a mixed‐valent AuI–AuIII species. Halide ion induces ligand‐to‐gold two‐electron transfer, producing a carbazolyldiphosphine analogue with a bridging chlorido ligand. This preorganized AuI–AuI species enables σ,π‐activation of alkynes and is an isolable precatalyst for highly selective heterocyclizations.