<p>Precision engineering of semiconductor nanomaterials remains difficult. Here we present a programmable approach to synthesizing a library of atomically precise semiconductor nanoclusters via cation exchange. Using a universal metal–ligand coordination complex to program cations and surface ligands, and a Cu₂₆Se₁₃ template cluster to control the anion lattice, we synthesize a homologous series of Zn₁₄Se₁₃, Cd₁₄Se₁₃ and Hg₁₄Se₁₃ clusters, all featuring a pair of prominent absorption peaks. The shared A₁₄B₁₃ framework with icosahedral anion packing and tetrahedral cation bonding serves as a blueprint for constructing chiral semiconductor nanostructures. Theoretical calculations reveal atom-like frontier orbitals, including triply degenerate P-type orbitals for holes and singlet S-type orbitals for electrons. The doublet absorptions originate from the spin–orbit splitting of the P → S transition. The precise and programmable synthesis is expected to enable atomic-level control over the optical, electronic and spin properties of semiconductor artificial atoms and their assemblies.</p><p></p>