Computational Design of Gallium Imides for Methane Activation

Activation of the strong non-polar C-H bonds in methane is difficult, especially in solution. In this work, computational modeling is used to modify NacNac gallium imide, which has recently been shown to cleave unactivated sp3 C-H bonds in organic substrates with the aim of making it suitable for methane activation. Density functional theory predicts that the 123 kJ mol−1 methane activation barrier for the experimentally employed gallium imide can be reduced to 93 kJ mol−1 by changing substituents around the active gallium center. Furthermore, pre-straining the gallium imide reduces the reaction barrier to just 62 kJ mol−1. Dimerization of the gallium imides can be prevented with bulky groups that do not affect the reaction barrier. Several modified NacNac gallium imides are thus shown to be viable for the homogeneous activation of methane and higher alkanes.