Primary selectivity in the activation of the carbon-hydrogen bonds of propane by silica supported zirconium hydride

The stoichiometric reaction between propane and(=SiO)(3)ZrH leads to the formation of a mixture of (= SiO)(3)ZrCH(CH3)(2) and (= SiO)(3)ZrCH2CH2CH3. The relative amounts of each complex resultant from the reaction was determined by (a) reaction of (= SiO)(3)ZrC3H7 with D2O to produce quantitatively a mixture of CH3CH3CH2D and CH3CHDCH3 which in turn were discriminated by mass spectroscopy, and (b) reaction of(= SiO)(3)ZrC3H7 with O-2 followed by HCl yielding 1-propanol and 2-propanol in low yield. Each of these methods indicated that (= SiO)(3)ZrCH2CH2CH3 was the major product of propane activation. The catalytic deuteration of propane by deuterium at room temperature catalysed by (= SiO)(3)ZrH showed that the primary C-H bonds of propane reacted seven times faster than the secondary C-H bonds. A mechanism of degenerate carbon-hydrogen bond activation is invoked for the latter reaction.