Abstract: A process for the preparation of preceramic metallopolysilanes is described. The process consists of contacting and reacting organohalogendisilanes with metal-containing compounds in the presence of a redistribution catalyst in an inert, essentially anhydrous atmosphere while removing volatile byproducts. The resulting metallopolysilanes contain significant amounts of aluminum, boron, chromium, lanthanum, molybdenum, neodymium, niobium, samarium, tantalum, titanium, tungsten, vanadium, yttrium, or zirconium. Such metallopolysilanes can be prepared with relatively low oxygen levels. These polymers are useful as chemical intermediates to synthesize organosilicon materials or polymers. These polymers are also useful, when fired at high temperatures, to form ceramic materials.

Abstract: Halogenated polycarbosilanes are prepared by reacting a polycarbosilane containing at least 0.1 weight percent Si-H groups with a halogenating reagent selected from the group consisting of chlorine, bromine, phosphorous pentachloride, phosphorous pentabromide, antimony pentachloride, N-chlorosuccinimide, N-bromosuccinimide, sulfonyl chloride, and mixtures of CH.sub.e X.sub.f and a free radical initiator where e is 0 or 1, f is 3 or 4, the sum (e+f) is 4, and X is chlorine or bromine. The halogenated polycarbosilanes can be further treated to produce other derivatized polycarbosilanes. The halogenated and derivatized polycarbosilanes can be converted to silicon carbide-containing ceramic materials by pyrolysis at elevated temperatures under an inert atmosphere.