A drop of a ligand exchange solution (10 mL acetonitrile, 200 µl HCl(aq), 200 µL 1,2ethanedithiol) was placed on the sample for about 7 s, removed by spinning the sample and rinsed with acetonitrile, followed by hexane. After the ligand exchange had been performed, the sample was stored in an air-and water free atmosphere.