Observable but Not Isolable: The RhAu24 (PET)18 1+ Nanocluster.

The synthesis and characterization of RhAu24 (PET)18 (PET = 2-phenylethanethiol) is described. The cluster is cosynthesized with Au25 (PET)18 and rhodium thiolates in a coreduction of RhCl3 , HAuCl4 , and PET. Rapid decomposition of RhAu24 (PET)18 occurs when purified from the other reaction products, precluding the study of isolated cluster. Mixtures containing RhAu24 (PET)18 , Au25 (PET)18 , and rhodium thiolates are therefore characterized. Mass spectrometry, X-ray photoelectron spectroscopy, and chromatography methods suggest a combination of charge-charge and metallophilic interactions among Au25 (PET)18 1- , rhodium thiolates and RhAu24 (PET)18 resulting in stabilization of RhAu24 (PET)18 . The charge of RhAu24 (PET)18 is assigned as 1+ on the basis of its stoichiometric 1:1 presence with anionic Au25 (PET)18 , and its stability is contextualized within the superatom electron counting rules. This analysis concludes that the Rh atom absorbs one superatomic electron to close its d-shell, giving RhAu24 (PET)18 1+ a superatomic electron configuration of 1S2 1P4 . Overall, an updated framework for rationalizing open d-shell heterometal dopant electronics in thiolated gold nanoclusters emerges.