title: Intercalation of Transition Metals into Stacked Benzene Rings: A Model Study of the Intercalation of Transition Metals into Bilayered Graphene.
abstract: Structures of neutral metal-dibenzene complexes, M(C6H6)2 (M = Sc-Zn), are investigated by using Møller-Plesset second order perturbation theory (MP2). The benzene molecules change their conformation and shape upon complexation with the transition metals. We find two types of structures: (i) stacked forms for early transition metal complexes and (ii) distorted forms for late transition metal ones. The benzene molecules and the metal atom are bound together by δ bonds which originate from the interaction of π-MOs and d orbitals. The binding energy shows a maximum for Cr(C6H6)2, which obeys the 18-electron rule. It is noticeable that Mn(C6H6)2, a 19-electron complex, manages to have a stacked structure with an excess electron delocalized. For other late transition metal complexes having more than 19 electrons, the benzene molecules are bent or stray away from each other to reduce the electron density around a metal atom. For the early transition metals, the M(C6H6) complexes are found to be more weakly bound than M(C6H6)2. This is because the M(C6H6) complexes do not have enough electrons to satisfy the 18-electron rule, and so the M(C6H6)2 complexes generally tend to have tighter binding with a shorter benzene-metal length than the M(C6H6) complexes, which is quite unusual. The present results could provide a possible explanation of why on the Ni surface graphene tends to grow in a few layers, while on the Cu surface the weak interaction between the copper surface and graphene allows for the formation of a single layer of graphene, in agreement with chemical vapor deposition experiments.
authors.affiliation: Department of Chemistry and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Il Seung
authors.initials: IS
authors.lastname: Youn
authors.affiliation: Department of Chemistry and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Dong Young
authors.initials: DY
authors.lastname: Kim
authors.affiliation: Department of Chemistry and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: N Jiten
authors.initials: NJ
authors.lastname: Singh
authors.affiliation: Department of Chemistry and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Sung Woo
authors.initials: SW
authors.lastname: Park
authors.affiliation: Department of Chemistry and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Jihee
authors.initials: J
authors.lastname: Youn
authors.affiliation: Department of Chemistry and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea.
authors.forename: Kwang S
authors.initials: KS
authors.lastname: Kim