SYNTHESIS AND SOLID-STATE NMR STRUCTURAL CHARACTERIZATION OF POLYSILOXANE-IMMOBILIZED PHOSPHINE, PHOSPHINE-AMINE AND PHOSPHINE-THIOL LIGANDSYSTEMS

Polysiloxane-immobilized phosphine ligand systems have been prepared b y hydrolytic condensation of mixtures of Si(OEt)(4) and (R'O)(3)Si(CH2 )(n)PPh2 (n = 2, R' = Me; n = 3, R' = Et). Polysiloxane-immobilized ph osphine-amine and phosphine-thiol ligand systems have been prepared by hydrolytic condensation of mixtures of Si(OEt)(4), (R'O)(3)Si(CH2)(n) PPh2 (n=2, R'=Me; n=3, R'=Et) and (R'O)(3)Si(CH2)(3)X (X=NH2, R'=Et; X =NHCH2CH2NH2, R'=Me) or (MeO)(3)Si(CH2)(3)SH. In the polysiloxane-immo bilized phosphine-amine and phosphine-thiol systems two types of ligan d groups are introduced into the polysiloxane matrix during the sol-ge l process. Solid-state C-13, P-31 and Si-29 NMR spectroscopy was used to investigate the structures of the polysiloxane-immobilized ligand s ystems - e.g., to determine the presence of unhydrolyzed/uncondensed a lkoxy groups, to determine the ratios of phosphine to phosphine oxide moieties, to determine details of the silicon-based backbone (relative populations of various types of RSi(-O-)(3) and Si(-O-)(4) moieties) and to establish domain homogeneity throughout a given material.