New hybrid diphosphates Ln2(NH2(CH2)2NH2)(HP2O7)2 4H2O (Ln = Eu, Tb, Er): synthesis, single crystal and powder X-ray crystal structure

Crystals of lanthanide ethylenediamine diphos phates Ln2(NH2(CH2)2NH2)(HP2O7)2·4H2O (Ln = Eu (1), Tb (2), Er (2)) have been synthesized and investigated by single crystal X-ray diffractometry (Eu and Tb phases) and by powder X-ray diffractometry (Er phase). The three structures resulted to be isostructural within triclinic space group P-1, with unit cell parameters of a = 6.5050(6) Å; b = 6.9990(2) Å; c = 9.8450(9) Å; ± = 81.548(5)°; ² = 80.631(19)°; ³ = 88.369(9)°; V = 437.44(6) Å3 (1), a = 6.4360(7) Å; b = 6.9480(12) Å; c = 9.816(4) Å; ± = 81.987(19)°; ² = 80.595(16)°; ³ = 88.591(13)°; V = 428.82(19) Å3 (2), a = 6.39658(2) Å; b = 6.86682(2) Å; c = 9.78849(3) Å; ± = 81.6811(4)°; ² = 80.2304(3)°; ³ = 88.3812(3)°; V = 419.255(3) Å3 (3).The three-dimensional network is built up by the repetition of ab-parallel layers of LnO8 polyhedra corner-sharing with (HP2O7) groups; ethylenediamine molecules lie between such layers, acting both as receptors and donors in strong hydrogen bonds which assure the stabilizing of the entire framework.