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Synthesis and solid-state NMR structural characterization of polysiloxane-immobilized phosphine-amine and phosphine-thiol ligand systems

1997; Elsevier BV; Volume: 212; Issue: 2-3 Linguagem: Inglês

10.1016/s0022-3093(96)00682-5

1873-4812

Jane J. Yang, Issa M. El‐Nahhal, I-Ssuer Chuang, Gary E. Maciel,

Zeolite Catalysis and Synthesis

Polysiloxane-immobilized phosphine ligand systems have been prepared by hydrolytic condensation of mixtures of Si(OEt)4 and (R′O)3Si(CH2)nPPh2 (n = 2, R′ = Me; n = 3, R′ = Et) Polysiloxane-immobilized phosphine-amine and phosphine-thiol ligand systems have been prepared by hydrolytic condensation of mixtures of Si(OEt)4, (R′O)3Si(CH2)nPPh2 (n = 2, R′ = Me; n = 3, R′ = Et) and (R′O)3Si(CH2)3X (X = NH2, R′= Et; X = NHCH2CH2NH2. R′ = Me) or (MeO)3Si(CH2)3SH. In the polysiloxane-immobilized phosphine-amine and phosphine-thiol systems two types of ligand groups are introduced into the polysiloxane matrix during the sol-gel process. Solid-state 13C, 31P and 29Si NMR spectroscopy was used to investigate the structures of the polysiloxane-immobilized ligand systems — e.g., to determine the presence of unhydrolyzed/uncondensed alkoxy 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.