Electron deficient polyarylenesiloxanes

Abstract

The syntheses and spectroscopic characterizations of a series of siloxane and siloxane chromiumtricarbonyl model complexes and polymers are reported. The siloxane model compound, a,a,a',a'-tetramethyl-O,O'-bistriisopropylsiloxy-l,4-benzenedimethanol, was prepared from a,a,a',a'-tetramethyl-l,4-benzenedimethanol in methylene chloride by reaction with chlorotriisopropylsilane/pyridine. The siloxane polymers were prepared from a,a,a',a'-tetramethyl-l,4-benzenedimethanol in methylene chloride by reaction with dichlorodimethylsilane/pyridine and were terminated with chlorotriethylsilane and chlorotriisopropylsilane. The chromiumtricarbonyl starting material, (116-a,a,a',a'-tetramethyl-l,4-benzenedimethanol)chromiumtricarbonyl, was prepared via the reaction of a,a,a',a'-tetramethyl-l,4-benzenedimethanol with chromiumhexacarbonyl in refluxing dibutylether/tetrahydrofuran under inert atmospheric conditions. The siloxane chromiumtricarbonyl complex, (116-a,a,a',a'-tetramethyl-O,O'-bistriisopropylsiloxy-l,4benzenedimethanol)chromiumtricarbonyl was prepared from (116-a,a,a',a'-tetramethyl1,4- benzenedimethanol)chromiumtricarbonyl by reaction with chlorotriisopropylsilane/pyridine in methylene chloride. The siloxane chromiumtricarbonyl polymers were iv prepared from (116-a,a,a',a'-tetramethyl-I,4-benzenedimethanol)chromiumtricarbonyI in methylene chloride by reaction with dichlorodimethylsilane/pyridine and were terminated with chlorotriisopropylsilane. All of these compounds were characterized by IR and by IH and l3e NMR spectroscopy. The molecular weights were estimated by NMR and viscosity measurements. The relative stabilities ofthe complexes are reported.