Studies on Gas-phase Cyclometalations of [ArNi(PPh3) n ]+ (n = 1 or 2) by Electrospray Ionization Tandem Mass Spectrometry

Gas-phase cyclometalation of [ArNi(PPh3) n ]+ (n = 1, 2) complexes have been studied by ESI-MS/MS. The electron-donating substituents of aromatic iodides in the para position were found to inhibit the cyclometalation process of losing ArH, while the electron-withdrawing substituents in the para position were found to enhance it. These results indicate that the cyclometalation process of losing ArH is favored by electron-deficient aromatic groups. In addition, the detailed dissociation pathways of the cationic nickel complexes were studied, and among these pathways, the process of aryl-aryl interchange was also found to proceed in ESI-MS/MS. [Copyright &y& Elsevier]