Direct solvothermal growth, crystal structures, and optical properties of one-dimensional lanthanide selenidoarsenate(v) polymers [Ln(dien)2(μ3-AsSe4)] (Ln = Nd, Sm):: the first example of an AsSe43- anion acting as a ligand to a lanthanide complex

Two novel lanthanide selenidoarsenates(V)[Ln(dien)2(mu 3-AsSe4)](Ln = Nd 1, Sm 2, dien = diethylenetriamine) were synthesized by the reactions of As2O3 and Se with Nd2O3 or Sm2O3 in dien under solvothermal conditions. 1 and 2 are in the orthorhombic crystal system with Iba2 and Pbca space groups, respectively. The [AsSe4](3-) anion acts as a tridentate mu(3)-AsSe4 ligand to bridge the lanthanide [Ln(dien)(2)](3+) complexes leading to one-dimensional neutral [Ln(dien)(2)(mu(3)-AsSe4)]infinity chains. The chains contact through hydrogen bonding to form network structures. The lanthanide center lies within a nine-coordinated environment involving six N atoms of two dien ligands and three Se atoms of two different tetrahedral [AsSe4](3-) anions forming a distorted monocapped square antiprism. The novel coordination polymers [Nd(dien)(2)(mu(3)-AsSe4)]infinity and [Sm(dien)(2)(mu(3)-AsSe4)]infinity are the. rst examples of solvothermally synthesized selenidoarsenates with [AsSe4](3-) anion acting as a ligand in lanthanide complexes. The band gaps of 2.11 eV for 1, and 2.18 eV for 2 have been derived from optical absorption spectra. TG-DSC curves show that two compounds remove coordinated dien ligands in a single step.