Investigation of Geminally Diaurated Arene Complexes in the Gas Phase

The stability of gem-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 (p-MeO, p-Me, m-MeO, m-Me) strengthen,
while the electron-withdrawing ones (p-Cl, p-CN, p-NO2, m-Cl, m-CN, m-NO2) weaken
the three-center two-electron bond. More stable gem-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.