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SCI: a robust and reliable density-based...
Journal article

SCI: a robust and reliable density-based descriptor to determine multiple covalent bond orders

Abstract

Very recently [J. Phys. Chem. A 2018, 122 (11), 3087–3095], we proposed to employ the Pauli energy to identify and determine strong covalent interactions (SCI), whose bond order are equal to or larger than two. This is done through the signature isosurface shape between the two bonding atoms. We discovered that the signature shape for a double, triple, and quadruple covalent bond is like a dumbbell, donut (torus), and four-beats, respectively. Systems with even higher bond orders were examined and confirmed. This work is a follow-up study of our previous work. The dependence of the signature isosurface shape on the choice of methodologies and basis sets is systematically investigated. Its effectiveness and robustness in determining bond orders are highlighted again with more examples. In addition, using the molybdenum dimer in different environments, e.g., in vacuum, sandwiched between molecules, and encapsulated in the C80 cage, as illustrative examples, we show that, generally speaking, bond strength and bond order are two different chemical concepts. For systems containing transition metals, it is not always true that a short metal-metal bond length corresponds to a larger bond order. Put together, these results should provide additional pieces of convincing evidence showing that the SCI index is a robust and reliable density-based descriptor to accurately determine multiple covalent bond orders.

Authors

Huang Y; Liu L; Rong C; Lu T; Ayers PW; Liu S

Journal

Journal of Molecular Modeling, Vol. 24, No. 8,

Publisher

Springer Nature

Publication Date

August 1, 2018

DOI

10.1007/s00894-018-3721-9

ISSN

1610-2940

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