Two types of products were isolated from the reaction of NH₄Se₂P(OR)₂ (R = Pr, Prⁱ), Cu(CH₃CN)₄PF₆, and Bu₄NI in a 3 ∶ 2 ∶ 2 molar ratio in diethyl ether. The formulation of 1, Cu₈(μ₈-Se)[Se₂P(OR)₂]₆, and 2, Cu₁₁(μ₉-Se)(μ₃-I)₃[Se₂P(OR)₂]₆, was confirmed by elemental analyses, positive FAB mass spectrometry, multinuclear NMR (¹H, ³¹P, and ⁷⁷Se), and X-ray diffraction (1a and 2b). The geometry in 1 can be described as a selenide-centered, slightly distorted Cu₈ cube with each edge of the cube being bridged by a selenium atom of the diselenophosphato (dsep) ligands . The sx dsep ligands, each capped on the square face of the cube, adopt a tetrametallic tetraconnective coordination pattern. The eleven copper atoms in 2 adopt the geometry of a 3,3,4,4,4-pentacapped trigonal prism with a selenium atom in the center. The coordination geometry for the central selenium atom is tricapped trigonal prismatic. In addition, the central core (Cu₁₁Se in 2) is further stabilized by three iodides and six dsep ligands. A unique ⁷⁷Se NMR pattern for the dsep ligands clearly indicates that local C_3h symmetry was retained in solution. Moreover, the octacoordinated and nonacoordinated selenium atoms in 1 and 2 are unequivocally characterized by the ⁷⁷Se NMR spectra, whose resonance frequencies are centered around −1150 and −1200 ppm, respectively.