We have investigated the simultaneous proton and hydride abstraction mechanism3 for various alkanes such as ethane, propane, n-butane, isobutane, isopentane and 2,3-diemthylbutane (hexane) for different pair framework-Al sites. We find linear Brønsted-Evans-Polanyi relations between the reduction energy of the monohydride site ([GaH]2+Z2-) and the activation barrier for C-H activation. We find systematic changes in the activation barrier for the simultaneous proton and hydride abstraction mechanism by changing the nature of the hydrogen donating carbon from primary to secondary to tertiary. These changes are quantified in terms of the group contribution relations to predict the activation barrier for the dehydrogenation reaction step. These combined group contribution and structure-activity relations enable use to predict the dehydrogenation activity corresponding to any combination of the active site structure and any given alkane.
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(3) Mota, C. J. A.; Bhering, D. L.; Ramirez-Solis, A. International Journal of Quantum Chemistry 2005, 105, 174.