1,1-Digoldallylium Complexes: Diaurated Allylic Carbocations Indicate New Prospects of the Coordination Chemistry of Carbon.

Reacting (NHC)(cyclopropenyl)gold(I) complexes with cationic gold complexes [(IPr)AuX] afforded extremely reactive allylium-1,1-diido-bridged digold intermediates. We prove the existence and constitution of this structure with FT-ICR-MS/MS, NMR, and UV-Vis-NIR experiments and isolated the nucleophilic addi-tion product [(Me)(Ph)(CCHC){Au(IPr)}2(SOMe2)]NTf2 with DMSO. Our computational investigation unveiled that the bond-ing situation of this -allylium-1,1-diido digold domain was best described as a three-center four electron bond with -backbond. The valence orbitals showed extreme delocalization and strong -interactions between the three centers Au1-C1-Au2. The bridging carbon atom C1 was best described as trigonal planar sp-hybridized carbon in this structure. Excitation succeeded in UV-Vis-NIR measurements with energies as low as near IR radiation.