687. Organosilyloxy-derivatives of metals. Part I. Alkylsilyloxy-derivatives of titanium, zirconium, niobium, and tantalum

Abstract

or 0, M = Ti, Zr, Nb, or Ta, and n is the valency of M, have been prepared by various methods. Their physicochemical properties have been studied and are compared with the corresponding metal tertiary alkoxides. The organosilyloxy-metal compounds appear to be less susceptible to hydrolysis or thermal decomposition than the metal tertiary alkoxides.TETRAKISTRIMETHYLSILYLOXYTITANIUM Ti(O*SiMe,), was first reported by English and Sommerl in 1955. Although other authors2*3*4s5 have since prepared this and other trialkylsilyloxytitanium compounds, the yields were often low and little was known about them when our systematic studies began. Furthermore we have extended these studies to cover other transition metals whose trialkylsilyloxy-derivatives are more difficult to prepare. Now we report the preparation of derivatives of titanium, zirconium, niobium, and tantalum together with the results of molecular-weight studies (ebulliometrically in benzene) and boiling points under reduced pressure.Preparative Methods.-English and Sommer's synthesis of tetrakistrimethylsilyloxytitanium involved the reaction between titanium tetrachloride and trimethylsilanol in benzene in the presence of ammonia, and they inferred that the low yield (18%) was caused by water produced in the acid-catalysed condensation of the silanol. Zeitler and Brown obtained a better yield (56%) by the silanolysis of titanium tetra-n-butoxide in boiling toluene :They isolated butoxytrimethylsilane among the products and it was thus clear that condensation of the silanol with the butyl alcohol liberated by silanolysis also produced water which hydrolysed the titanium compounds. This behaviour confirmed our independent experiences with the trimethylsilanolysis of titanium or zirconium isopropoxides and it was clear that good yields of these trimethylsilyloxy-derivatives would only result under conditions which suppressed the condensation reactions of the silanol. Obviously the concentrations of silanol and liberated alcohol (in the silanolysis) must be minimised. By

Metal Oxide Trialkylsilyloxide Polymers (Polytrialkylsiloxanometalloxanes): Part I. Titanium Oxide Trimethylsilyloxide Polymers

“…Evaporation in vacuo a t room temperature gave as condensate a small quantity of silanol, hexainethyldisiloxane, and water, and left a liquid containing a white precipitate (1). The formation of silanol, disiloxane, and water suggested that some hydroxy compounds, e.g.…”

“…In a previous communication (1) we reported the preparation and properties of some trialkylsilyloxy derivatives of titanium, zirconium, niobium, and tantalum. I t was observed that these compounds were less susceptible to hydrolysis than the metal alkoxides and it was suggested that this property was connected with the water-repellant nature of the trialkylsilyloxy group.…”

Metal Oxide Trialkylsilyloxide Polymers. Part VI. Aluminum Oxide Trimethylsilyloxides

“…The solid product was purified by sublimation under vacuum. Analysis by general methods (8) Hydrolysis was carried out in dioxane which had been refluxed over sodium for several hours and fractionally distilled. A weighed amount of the silyloxide (2.0-2.5 g) was dissolved in dioxane (30 g) at room temperature, and a weighed amount of water ( h mole per mole metal atoms) was added to the stirred solution.…”

“…All hydrolysis products were analyzed for aluminum and silicon (8) and their molecular weights were determined by cryoscopy in cyclohexane. Infrared spectra were recorded for several products at concentrations of 3.0, 4.0, 5.0, and 6.0 wt.% in cyclohexane, using KBr cells of path length 0.1 mm and a Beckman IR-7 spectrophotometer.…”

THE PREPARATION OF ALKOXIDES AND TRIETHYLSILANOLATES OF Ti, Zr, V, Nb, Ta, AND Sn FROM THE DIALKYLAMIDES

“…Metals, except vanadium, were determined gravin~etrically a s the ignited oxides (A), and silicon a s silica (4). An oxidation inethod ( 5 ) was used for the determination of ethoxy and isopropoxy groups, and basic nitrogen was estimated in a modified I<jeldahl apparatus (I).…”