On the bonding of methane with magnetic Fe4 clusters

Fe 4 0 + , 1 + – ( CH 4 ) n , n = 1–4, systems were studied with the BPW91/6-311++G(2d,2p) method. In the 2S = 14 (S = total spin) Fe4–CH4 ground state, (GS) two weak CH–Fe bonds are formed and two C–H bonds are activated. For the higher 2S = 12 and 10 energy states, a weak Fe–C bonding also appears. The CH4 adsorption shows magnetic selectivity, because the GS have 2S = 14, 12, and 12 for n = 1, 2, and 3, respectively; n = 4 does not hold. Complete saturation was achieved for [Fe4–(CH4)n]+, n = 1–4, which have 2S = 11 GSs and similar C–H activation.