Estudo sobre teluroxanos gigantes: novos exemplos e metodologias para derivatização

Abstract

The current work describes the synthesis and structural characterization of a new class of compounds, the giant telluroxanes. Eleven new compounds were obtained: [{(PhTe)18{M(NO3)(H2O)}O24}2I16] (M = Y (1), La (2), Eu (3), Lu (4)), [{(PhTe)18- {Nd(dmf)2I}O24}2I16]∙4dmf∙5H2O (5), [{(PhTe)18{Y(dmf)(H2O)}O24}2Br18]∙5dmf∙6H2O (6), [{(PhTe)18{La(dmf)2(H2O)}O24}2Br18]∙8H2O (7), [{(PhTe)18{Ce(dmf)2Br)}O24}2(SO4)2Br12] (8), [{(PhTe)18{Y(NO3)(H2O)}O24}2(PhSeO2)4(NO3)12] (9), [{(PhTe)18{Ce(NO3)2}O24- (PhSeO2)}2{Ce2(NO3)6}(NO3)8]∙6C4H8O2 (10) and [{(PhTe)18{Na(diox)(H2O)}O24}2- (HNEt3)4Cl18]∙3dmf∙10H2O (11). The research about the synthesis of giant telluroxanes is scarce, despite their structural versatility and promising applications in materials science, such optical materials and CO2 trapping. The methodology used for the synthesis of these compounds is related to the hydrolysis of phenyltellurium halides (PhTeI3, PhTeBr3, [PhTeI]4 and PhTeCl – the last two prepared in situ) and subsequent aggregation and condensation in the presence of different metallic salts, forming structures containing two cationic half-spheres of composition [{(PhTe)18{ML}O24}]n+, interconnected and stabilized by chalcogen bonds Te∙∙∙X (X = Cl, Br, I) or even by covalent bonds performed by the use of a spacer ligand, as phenylseleninate. The halfspheres are composed of two macrocycles: (PhTe)12O12 and (PhTe)6O6, the latter being important for the cluster, as accommodates oxophilic metal ions in a rigid coordination environment formed by the six oxygen atoms, similar to 18-crown-6 ligand. Both macrocycles are connected by –O2- bonds. The tests carried out revealed that the choice of metal ions does not depend on their oxidation state, but depends on their ionic radii since each ion must accommodate more than six bonds in its coordination sphere. It was also verified that changes in the solvent and anion from metallic salt cause variation in the morphology of the half-spheres and, consequently, the entire cluster. Single-crystal X-ray diffraction analysis proved to be the main characterization technique, followed by infrared, Raman, UV-Vis spectroscopies, as well as elemental analysis, melting point determination and mass spectrometry.