Syntheses, crystal structures and magnetic properties of two new chromium chalcogenides Cr(en)3SbSe4 and Cr(en)2AsSe3

We report two new chromium chalcogenides Cr(en)(3)SbSe4 and Cr(en)(2)AsSe3 which were obtained by solvothermal reactions at 170 degrees C. Cr(en)(3)SbSe4 adopts the tetragonal space group P4(2)bc with isolated [Cr(en)(3)](3+) ions and [SbSe4](3-) tetrahedrons. Cr(en)(2)AsSe3 is a molecular crystal with the monoclinic space group P2(1)/n. It has [Cr(en)(2)Se-2](-) octahedrons and [AsSe3](3-) triangle cones which are edge shared by Se atoms. Cr(en)(3)SbSe4 has a band gap of 2.3 eV, whereas Cr(en)(2)AsSe3 displays multiple-absorption characters with two absorption edges at 1.7 and 2.2 eV, respectively. Remarkably, Cr(en)(3)SbSe4 is a Curie-Weiss paramagnet between 2 and 300 K with an effective magnetic moment of 3.98 mu B, and is a potential magneto-caloric material with -Delta S-m = 16.3 J (kg K)(-1) at 4 K and Delta H = 8 T. Cr(en)(2)AsSe3 shows antiferromagnetism below 9 K. (c) 2018 Published by Elsevier B.V.