Herein, we present a novel approach towards organometallic group 13/15-compounds, i.e. the reaction of nanoparticular arsenic and antimony with low-valent aluminium species. The reaction of the two-electron reducing agent [AlCp*]4 (Cp* = C5Me5) with arsenic nanoparticles gave rise to a mixture of two unprecedented deca- and dodecanuclear Al-As clusters. In contrast, the analogous transformation with nanoparticular antimony yielded the already known Al-Sb compound [(AlCp*)3Sb2]. Additionally, two different dialanes [AlCp*X]2 (X = Br, I) were employed as one-electron reducing agents, forming calix like coordination compounds upon reaction with nano arsenic. The isolated species significantly enlarge the accessible structural variety of molecular group 13/15 compounds, highlighting the exceptional utility and reactivity of nanoscale group 15 precursors.