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

Crystals of lanthanide ethylenediamine diphos phates Ln 2 (NH 2 (CH 2 ) 2 NH 2 )(HP 2 O 7 ) 2 · 4 H 2 O ( 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; α = 81.548(5)°; β = 80.631(19)°; γ = 88.369(9)°; V = 437.44(6) Å 3 (1) , a = 6.4360(7) Å; b = 6.9480(12) Å; c = 9.816(4) Å; α = 81.987(19)°; β = 80.595(16)°; γ = 88.591(13)°; V = 428.82(19) Å 3 (2) , a = 6.39658(2) Å; b = 6.86682(2) Å; c = 9.78849(3) Å; α = 81.6811(4)°; β = 80.2304(3)°; γ = 88.3812(3)°; V = 419.255(3) Å 3 (3) .The three-dimensional network is built up by the repetition of ab -parallel layers of Ln O 8 polyhedra corner-sharing with (HP 2 O 7 ) 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.