Dehydrogenative coupling of primary alkyl silanes using Wilkinsonʹs catalyst

Primary alkyl silanes (RSiH3, where R=n-C12H25 or n-C8H17) undergo dehydrogenative coupling in the presence of (Ph3P)3RhCl (1) to give oligomeric products. 29Si{1H}-NMR and gel permeation chromatography suggest that chains of up to 5–6 silicons are forming in these reactions. Variations in product distributions observed for these two substrates, of supposedly comparable SiH reactivity, may be correlated with the relative rates of departure of hydrogen gas from the reaction mixtures. The sensitivity of this system to H2(g) concentrations may ultimately allow control over specific chain lengths formed.