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The Atoms in Molecules Theory has been applied to analyze bonding
properties in potentially hypervalent structures with
chalcogen(O, S or Se)-chalcogen(O or S) bonds.
The topological analyses [based upon the electron charge density
r(r), its Laplacian
Ñ2r(r),
bond ellipticity, local energy density Ed(r)] and
the charges clearly displayed the dependence of the bonding properties with
the central atom:
(a) When the central atom is oxygen, the main electron charge concentration
remains in the surroundings of the central atom, yielding a very
weak coordinate bond.
(b) Bonding to the central sulfur and selenium atoms is consistent
with a model of a highly polarized sigma-bond, its
strength depending mainly on electrostatic interactions, so,
no evidence was found for double bonding, which has so
far been the conventional way to describe the interaction
in these systems.
The equilibrium geometries were optimized by both density functional
theory with a hybrid functional (B3LYP) and by ab initio
methods at the MP2(full) level, using the 6-311+G* basis set.
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