In this study, we explore for the first time interactions of atomically precise noble metal nanoclusters (NCs) in the gas phase, revealing fundamental nanoscale reactivity beyond solvent effects. Using ion-selected mass spectrometry and theoretical calculations, we investigate and establish the formation of a Coulombic ion pair between two oppositely charged NC ions, Ag17(o1-CBT)123- (o1-CBT = ortho-1-carboranethiol) and Cu14(o9,12-CBDT)6+ (o9,12-CBDT = ortho-9,12-carboranedithiol), that undergo metal exchange to form alloy NCs, focusing on how atom exchange processes can be understood in the isolated gas phase. The Coulombic contribution to the binding energy of the NC ion pair was estimated to be ∼66%, while the rest was from intercluster ligand interaction through van der Waals forces. Similar behavior across diverse oppositely charged NC ion pairs, including Ag29(1,3-BDT)123- (1,3-BDT = 1,3-benzenedithiol), PdAg28(1,3-BDT)124-, PtAg28(1,3-BDT)124-, Ag13Cu4(o1-CBT)123-, Au25(2-PET)18- (2-PET = 2-phenylethanethiol), PdAg24(2,4-DMBT)182- (2,4-DMBT = 2,4-dimethylbenzenethiol), PtAg24(2,4-DMBT)182-, Cu14(o9,12-CBDT)6+, Ag21(m9-CBT)12+ (m9-CBT = meta-9-carboranethiol), and Ag22(2,5-DMBT)12Cl4(DPPB)4+ (DPPB= diphenylphosphenobutane), confirms the universality of this process. Dithiol ligand exchange was observed between Ag29(1,3-BDT)123- and Cu14(o9,12-CBDT)6+ in their Coulombic adducts for the first time. These results highlight the intrinsic, solvent-independent reactivity of NCs in the gas phase.
Acharya et al. (Tue,) studied this question.