| A series of novel polysiloxanes containing transition metals were synthesized via dehydrogenative coupling reactions assisted by Wilkinson's catalyst. Ferrocene-grafted siloxanes were prepared in high yields (∼79--97%) via Rh-catalyzed dehydrogenative coupling of a series of monomeric, polymeric, and cyclic hydrosiloxanes with ferrocenemethanol. Wilkinson's catalyst was the most efficient of those surveyed (Karstedt's catalyst, H2PtCl 6, Co2(CO)8, 10% Pd/C, 10% Pt/C, 5% Rh/C) with respect to yield and selectivity. Benzene and toluene were better solvents than tetrahydrofuran and methylene chloride.; Siloxanes containing sigma-complexes of metal halides were prepared from amine-functionalized polysiloxanes. N,N,N',N'-tetramethyl-1,3-diamino-2-propanol was successfully attached to the polymer backbone via dehydrogenative coupling reaction using Wilkinson's catalyst. Transition metal halides such as FeCl 2, FeCl3, CoCl2, NiCl2, and PtCl 2 were complexed with diamine functionalized polysiloxanes. The magnetic properties of the paramagnetic polymers were investigated by superconducting quantum interference device (SQUID) which showed Curie-Weiss behavior at temperatures below 20 K.; Polysiloxane containing mixed sigma- and pi-complexes were prepared from dehydrogenative coupling of ferrocenemethanol (1) and N,N,N',N'-tetramethyl-1,3-diamino-2-propanol (L4) with poly(methylhydrosiloxanes) (b). Incorporation of CoCl2, NiCl2, and PtCl2 into the polymers via complexation with diamine ligands afforded novel polysiloxanes with pendent mixed sigma- and pi-complexes.; Shaped magnetic silicon oxycarbide ceramics containing binary and ternary metal alloy nanoparticles were prepared from pyrolysis of metal-containing polysiloxanes in good ceramic yields. Ceramics containing PtFe, CoFe, NiFe, and PtCoFe were successfully prepared. The ceramic materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and vibrating sample magnetometry (VSM). Magnetic silicone rubber films containing Co, Pt, and Ni were prepared by blending metal-functionalized polysiloxanes with silicone resins, followed by thermal treatment at 200°C. The films were analyzed by SEM, XRD, and VSM. |
