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The Boron conundrum: the case of cationic clusters Bn+ with n = 2–20
Ist Teil von
Theoretical chemistry accounts, 2012, Vol.131 (6)
Ort / Verlag
Berlin/Heidelberg: Springer-Verlag
Erscheinungsjahr
2012
Link zum Volltext
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
We investigate the molecular and electronic structure and thermochemical properties of the cationic boron clusters B
n
+
with
n
= 2–20, using both MO and DFT methods. Several functionals are used along with the MP2, G3, G3B3, G4, and CCSD(T)/CBS methods. The latter is the high accuracy reference. While the TPSS, TPSSh, PW91, PB86, and PBE functionals show results comparable to high-accuracy MO methods, both BLYP and B3LYP functionals are not accurate enough for three-dimensional (3D) structures. A negligible difference is observed between the B3LYP, MP2, and CCSD(T) geometries. A transition between 2D and 3D structures occurs for this series at the B
16
+
–B
19
+
sizes. While smaller clusters B
n
+
with
n
≤ 15 are planar or quasi-planar, a structural competition takes place in the intermediate sizes of B
16–19
+
. The B
20
+
cation has a 3D tubular shape. The standard heats of formation are determined and used to evaluate the cluster stability. The average binding energy tends to increase with increasing size toward a limit. All closed-shell species B
n
+
has an aromatic character, but an enhanced stability is found for B
5
+
and B
13
+
whose aromaticity and electron delocalization are analyzed using the LOL technique.