Selenium Oxoanion Compounds of Palladium(II)

Three new palladium compounds, PdSeO₃, PdSe₂O₅, and Na₂Pd(SeO₄)₂, containing selenium oxoanions of both Se(IV) and Se(VI) have been prepared under mild hydrothermal conditions. PdSe₂O₅ and Na₂Pd(SeO₄)₂ both possess one-dimensional structures. Within the structure of PdSe₂O₅, [PdO₄] square planar building blocks are joined together through diselenite, Se₂O₅^2-, anions, and form a zigzag chain along the <i>c</i> axis. In Na₂Pd(SeO₄)₂, [PdO₄] units are connected by two selenate, SeO₄^2-, anions, and extend along the <i>a</i> axis to form a [Pd(SeO₄)₂]^2- chain. Na⁺ cations reside in the space between the [Pd(SeO₄)₂]^2- chains and act as counter cations. Unlike above two compounds, PdSeO₃ exhibits a layered structure. In the structure of PdSeO₃, [PdO₄] units are connected to each other by corner-sharing and form a zigzag chain along the <i>b</i> axis. The chains are further joined together by tridentate selenite, SeO₃^2-, anions to form layers in the [<i>ab</i>] plane that stack along the <i>c</i> axis. Crystallographic data:  (193 K; Mo Kα, λ = 0.71073 Å):  PdSeO₃, monoclinic, space group <i>P</i>2₁/<i>m</i>, <i>a</i> = 3.8884(5) Å, <i>b</i> = 6.4170(8) Å, <i>c</i> = 6.1051(7) Å, β = 96.413(2)°, <i>V</i> = 151.38(3) ų, <i>Z</i> = 2; PdSe₂O₅, monoclinic, space group <i>C</i>2/c, <i>a</i> = 12.198(2) Å, <i>b</i> = 5.5500(8) Å, <i>c</i> = 7.200(1) Å, β = 107.900(2)°, <i>V</i> = 463.8(1) ų, <i>Z</i> = 4; Na₂Pd(SeO₄)₂, triclinic, space group <i>P</i>1̄, <i>a</i> = 4.9349(11) Å, <i>b</i> = 5.9981(13) Å, <i>c</i> = 7.1512 (15) Å, α = 73.894(4)°, β = 86.124(4)°, γ = 70.834(4)°, <i>V</i> = 192.03(7) ų, <i>Z</i> = 1.