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The Cu 7 Sc Cluster is a Stable σ‐Aromatic Seven‐Membered Ring
Author(s) -
Höltzl Tibor,
Janssens Ewald,
Veldeman Nele,
Veszprémi Tamás,
Lievens Peter,
Nguyen Minh Tho
Publication year - 2008
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200700752
Subject(s) - scandium , chemistry , cluster (spacecraft) , copper , ring (chemistry) , aromaticity , atomic orbital , density functional theory , crystallography , atomic physics , electron , computational chemistry , molecule , inorganic chemistry , physics , organic chemistry , quantum mechanics , computer science , programming language
Density functional theory calculations demonstrate that the global minimum of the Cu 7 Sc potential energy surface is a seven‐membered ring of copper atoms with scandium in its center, yielding a planar D 7 h structure. Nucleus‐independent chemical shifts [NICS(1) zz and NICS(2) zz ] show that this cluster has aromatic character, which is consistent with the number of 4s electrons of copper and scandium plus the 3d electrons of scandium satisfying Hückel’s rule. According to a canonical MO decomposition of NICS(1) zz and NICS(2) zz , the MOs consisting of the 4s atomic orbitals are mainly responsible for the aromatic behavior of the cluster. The electron localizability indicator (ELI–D) and its canonical MO decomposition (partial ELI–D) suggest that a localized basin is formed in Cu 7 Sc by the copper atoms whereas the two circular localized domains are situated below and above the ring. The planar Cu 7 Sc cluster can thus be considered as a σ‐aromatic species. These findings agree with the phenomenological shell model.