A synchrotron X-ray study of the electron density in Y₂BaCuO₅

The deformation density (Δρ) for Y₂BaCuO₅, barium diyttrium cuprate, determined by single-crystal X-ray diffraction with synchrotron radiation, is affected to only a limited degree by the bonding interactions involving the O anions. Electron density is strongly depleted along the cation–cation contacts within the mirror plane in the structure and is transferred to regions between mirror planes that do not lie along short cation–cation vectors. The structural geometry for the CuO₅ moiety, with the Cu atom in the +2 state, closely resembles that of the Cu₂O₅ group in YBa₂Cu₃O_7−δ, for which the +3 state involvement for Cu has been suggested. Space group Pnma, orthorhombic, M_r = 458.68, a = 12.1793 (7), b = 5.6591 (5), c = 7.1323 (4) Å, V = 491.6 ų, Z = 4, D_x = 6.197 Mg m⁻³, λ = 0.9 Å, μ_0.9 = 28.893 mm⁻¹, F(000) = 812, T = 293 K, R = 0.020, wR = 0.020, S = 3.09 (5) for 2225 unique reflections.

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