A copper cluster protected with phenylethanethiol

A copper cluster protected with 2-phenylethanethiol (PET) exhibiting distinct optical features in UV/Vis spectroscopy is reported. Matrix-assisted laser desorption ionisation mass spectrometry of the cluster shows a well-defined molecular ion peak at m/z 5,800, assigned to ∼Cu38(PET)25. Fragmented ions from the cluster show the expected isotope patterns in electrospray ionisation mass spectrometry. The as-synthesized cluster was well-characterised using other tools as well. Clusters undergo decomposition in about 2 h after synthesis as a metallic few-atom core of copper is highly unstable. The products of decomposition were also characterised.