Das erste Oxocuprat(I) mit hantelförmigem Anion: KNa2[CuO2]

The First Oxocuprate(I) with Dumb-bell-like Anion: KNa₂[CuO₂] For the first time KNa₂[CuO₂] was prepared in transparent, dark yellow single crystals from KO_0.48 NaO_0.50 and Cu₂O (sealed cu-cylinders, 680°C, 30 d). The crystal structure, I 4mm, with a = 432.7(3), c = 1089.1(5) pm, Z = 2, D_x = 2.94 g/cm³, D_pyk = 2.89 g/cm³ was solved (four-circle-diffractometer PW 1100, 347 I₀ (hkl), MoKα; R = 0.073, R_x = 0.069). The structure of KNa₂[CuO₂] may be regarded as a “stuffed derivative” of XeF₂ with dumb-bell-like [CuO₂] units. The C.N. of the two crystallographically independent O^2? are 6 and 9, respectively. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated.