To What Extent Do Iodomethane and Bromomethane Undergo Analogous Reactions?

Iodomethane and bromomethane (CH 3 I/CH 3 Br) are common chemicals, but their chemistry on nanometals is not fully understood. Here, we analyze the reactivity of Rh n + ( n = 3-30) clusters with halomethanes and unveil the spin effect and concentration dependence in the C-H and C-X bond activation. It is found that the reactions under halomethane-rich conditions differ from those under metal-rich conditions. Both CH 3 I and CH 3 Br undergo similar dehydrogenation on the Rh n + clusters in the presence of small quantity reactants; however, different reactions are observed in the presence of sufficient CH 3 I/CH 3 Br, showing dominant Rh(CH 3 Br) x + ( x = 1-4) products but a series of Rh n C x H y I z + species ( x = 1-4, y = 1-12, and z = 1-5) pertaining to H 2 , HI, or CH 4 removal. Density functional theory calculations reveal that the dehydrogenation and demethanation of CH 3 Br are relatively less exothermic and will be deactivated by sufficient gas collisions if helium cooling takes away energy immediately; instead, the successive adsorption of CH 3 Br gives rise to a series of Rh(CH 3 Br) x + species with accidental C-Br bond dissociation.