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, X˭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 (M˭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.