SYNTHESIS AND SOLID-STATE NMR STRUCTURAL CHARACTERIZATION OF POLYSILOXANE-IMMOBILIZED THIOL-AMINE METAL(II) COMPLEXES

Abstract

The polysiloxane-immobilized thiol, amine, and thiol-mine ligand systems P-(CH₂)₃X (where P represents the siloxane network, Xdbnd]SH,NH₂, or hybride of amine and thiol ligand groups) have been made via the sol-gel process by hydrolytic condensation of Si(OEt)₄ and (MeO)₃Si(CH₂)₃X. The immobilized polysiloxanes thiol-acetate P-(CH₂)₃SCH₂COOMe and glycinate P-(CH₂)₃NHCH₂COOMe have been prepared by the reaction of the corresponding polysiloxane system P-(CH₂)₃SH, or P-(CH₂)₃NH₃ with methylchloroacetate. The immobilized thiol-amine ligands form metal(II) complexes when treated with aqueous metal(II) ion solutions (Mdbnd]Ni²⁺, Cu²⁺, Cd²⁺. Hg²⁺). High-resolution solid state NMR studies have been used to characterize these immobilized ligand systems and their metal(II) treated samples. ²⁹Si CP-NMR spectra suggest that these ligand systems undergo some leaching(1–4%) of small oligomers when treated with aqueous acid and metal ion solutions. ¹⁵N CP-NMR results show that substantial proportion of amine groups is coordinated to metal ions.