anti- and syn-sesquihomodiamantenes (SDs) were prepared and structurally characterized. anti-SD and parent sesquihomoadamantene were CH-bond functionalized by utilizing a phase-transfer protocol. The density functional theory-computed ionization potentials of unsaturated diamondoid dimers correlate well with the experimental oxidation potentials obtained from cyclic voltammetry. Similar geometries ensue for both the reduced and ionized SD states, whose persistence is supported by the β-hydrogen's spatial sheltering. This makes SDs promising building blocks for the construction of diamond materials with high stability and carrier mobility.