Síntese e análise estrutural de polímeros bidimensionais de seleninatos e selenonatos metálicos

Abstract

In this work, the characterization of lithium and silver complexes selenonato and seleninato ligands, respectively, is described. These are the first examples of X-ray characterization of selenonato and seleninato complexes in the literature. Silver phenylseleninate, Ag(O2SeC6H5), 1 was obtained by the reaction with silver nitrate and one equivalent of the ammonium phenylselenate. Lithium selenonate, Li(O3SeC6H5), 2 was obtained by the reaction with lithium acetate with phenylselenonic acid. Crystals of compound 1 were obtained by the crystallization in concetrated aqueous ammonia. The single crystal X-ray structural determination found that the crystals belong to the triclinic system, space group P-1 with cell parameters a= 4,7417(7) Å, b= 4,7867(6) Å, c= 14,97692) Å, α= 91,753(11)°, β= 99,104(9)° and γ = 90,122(8)°. Solution and refinement gave R1= 0,0528 and wR2= 0,1404. In the structure of 1, the Ag+ íon is five coordinate with an approximate square pyramidal coordination geometry, formed by the oxygen atoms of four different phenylseleninate ligands, which form bridges between the metal centers creating a two-dimensional layered structure parallel to the crystallographic bc plane. This compound presents the interplanar distance betwen the layers of 7,48802(12) Å. Compound 2 was crystallized from a water:acetone (2:1 v/v) mixture resulting in the hydrated compound Li(PhSeO3)(H2O)3, 3, which belongs to the monoclinic space group P21/c, with cell parameters a = 11,3410(11) Å, b = 7,6180(8), c = 12,3021(3) Å and β = 91,720(6)°. Solution and refinement gave R1= 0,0423 and wR2= 0,0707. The íon Li+ shows a tetrahedrical coordination geometry, formed by one oxygen atom of the phenylselenonate ligand and three oxygen atoms of the three water molecules. The complex shows a net of hydrogen bonds in the solid state, forming a complex two-dimensional layer structure parallel to the crystallographic bc plane.