Organometallic chemistry of new carbon materials. Structure and dynamic behavior of group 6 metal tricabonyl complexes of graphene and perforated graphene: a DFT study

Abstract

The mechanism of inter-ring haptotropic rearrangements (IRHR) was investigated by DFT for tricarbonyl η 6 -complexes of group 6 metals (M = Cr, Mo, W) of coronene (I-M), kekulene (II-M) and a model graphene (III-M). The computed η 6 ,η 6 -IRHR activation barriers in the middle size PAHs I-M, and II-M were calculated to be substantially lower than in the case of complexes of relatively small size PAHs such as naphthalene chromium tricarbonyl (ΔG # ≈ 20-25 kcal mol -1 vs. ≈ 30 kcal mol -1 ). The barrier is further lowered in the case of the model graphene complex III-Cr (ΔG # ≈ 13 kcal mol -1 ). An even lower barrier is found for III-Mo (ΔG # ≈ 10 kcal mol -1 ), whereas it slightly increases for III-W (ΔG # ≈ 14 kcal mol -1 ).

DFT Investigation of the η6 ⇌ η6-Inter-ring Haptotropic Rearrangement of the Group 8 Metals Complexes [(graphene)MCp]+ (M = Fe, Ru, Os)

“…It is noteworthy to mention that the computed gas-phase IRHR activation barriers Δ G ‡ ≈ 28–30 kcal/mol (see Table ) are significantly lower than the activation barriers computed for the similar processes in (MCp) + (M = Fe, Ru, Os) complexes of the middle size PAHs (Δ G ‡ ≈ 36–41 kcal/mol). , In the group 8 triad, the largest activation barrier is found for Fe and the lowest for Ru, the Os case being intermediate. This is in line with what we found earlier for the similar systems of the group 6 metals (Cr, Mo, W): the second metal of the triad affords the smallest IRHR activation barrier. , …”

“…This was already proven computationally by us for the group 6 metals (Cr, Mo, W) tricarbonyl complexes with the middle-sized kekulene and coronene 47 as well as with large-sized graphene. 48,49 Also, this finding was proven computationally by Nunzi et al and by Zhulyaev for these complexes with nanotubes 50,51 in comparison with the complexes of smaller size PAH such as naphthalene. 11 Sato et al, who computationally compared (CpRu) + −coronene complexes to smaller PAHs, also found this trend.…”

“…This is in line with what we found earlier for the similar systems of the group 6 metals (Cr, Mo, W): the second metal of the triad affords the smallest IRHR activation barrier. 48,49 Energy Decomposition Analysis Results. A deeper insight into the bonding variations along the IRHR process is provided by the energy decomposition analysis (EDA) carried out with the ADF program (see Computational Methods).…”

“…Although the ML n OMGs prefer to coordinate with peripheral rings of PAH, ,,− this choice was driven by the statistical significance of the central location in pristine graphene . Moreover, it has been previously shown that IRHR activation barriers depend poorly on the OMG localization on the plane of large PAH ligands, , which further justifies our choice of the ML n OMGs localization. The structures of the investigated [(η 6 -C 96 H 24 )­MCp] + (M = Fe, Ru, Os) complexes ( 1 and 2 ) are shown in Figure .…”