Investigation of Geminally Diaurated Arene Complexes in the Gas Phase

The stability of <i>gem</i>-diaurated arene complexes [Au₂(L)₂(μ-aryl)]⁺ has been investigated by collision-induced dissociation (CID) experiments and density functional theory (DFT) calculations. Performed mass spectrometric experiments revealed the influence of arene-ring substituents and a gold supporting ligand L on the stability of the corresponding diaurated complexes. From the determined appearance energies it emerged that the electron-donating substituents (<i>p</i>-MeO, <i>p</i>-Me, <i>m</i>-MeO, <i>m</i>-Me) strengthen, while the electron-withdrawing ones (<i>p</i>-Cl, <i>p</i>-CN, <i>p</i>-NO₂, <i>m</i>-Cl, <i>m</i>-CN, <i>m</i>-NO₂) weaken the three-center two-electron bond. More stable <i>gem</i>-diaurated complexes were found with electron-poor supporting ligands. It was found, however, that the electronic influences can be surpassed by the steric factors. Experimental results agree well with the performed DFT calculations at the mPW1PW91/cc-pVDZ:LanL2DZ­(Au) level of theory