Anion–Anion Chemistry with Mass‐Selected Molecular Fragments on Surfaces

While reactions between ions and neutral molecules in the gas phase have been studied extensively, reactions between molecular ions of same polarity remain relatively unexplored. Herein we show that reactions between fragment ions generated in the gas phase and molecular ions of the same polarity are possible by soft‐landing of both reagents on surfaces. The reactive [B(12)I(11)](1−) anion was deposited on a surface layer built up by landing the generally unreactive [B(12)I(12)](2−). Ex‐situ analysis of the generated material shows that [B(24)I(23)](3−) was formed. A computational study shows that the product is metastable in the gas phase, but a charge‐balanced environment of a grounded surface may stabilize the triply charged product, as suggested by model calculations. This opens new opportunities for the generation of highly charged clusters using unconventional building blocks from the gas phase.