Calorimetric Studies and Crystal Structure of [C2H10N2]5(Sb2Br11)2·4H2O

The chemical preparation and the main crystallographic, calorimetric, and structural features are given for a new alkyldiammonium antimony halogenide. [NH3(CH2)2NH3]5(Sb2Br11)2·4H2O salt is monoclinic P21/a with unit-cell dimensions a = 14.346(2), b = 13.206(1), c = 17.027(2) Å, β = 113.05(1)°, Z = 2; Dm = 2.985 M g−3; Dx = 2.941 M g−3; μ = 127.3 cm−1; F(000) = 2388; T = 298 K; R = 0.052 and Rw = 0.057 for 4136 observed reflections. The examination of the structure shows a layer arrangement parallel to the b axis: planes of (Sb2Br11)5− bioctahedra alternate with planes of [(CH2)2(NH3)2]2+. The (Sb2Br11)5− bioctahedra are connected through O(W)–H…Br hydrogen bonds, so that infinite chains of the composition [Sb2Br11(H2O)]n5n− are formed in the structure parallel to the b axis. The structure of this compound is built from (Sb2Br11)5− anions, [(CH2)2(NH3)2]2+ cations, and zeolitic water molecules connected by hydrogen bonds. The thermogravimetric analysis and differential scanning calorimetric studies show that the dehydration of this salt occurs in two steps: at 377 and 391 K, respectively, with a loss of two water molecules per step. The anhydrous salt starts to decompose at 490 K.