Chemical bonds from through-bridge orbital communications in prototype molecular systems

Nalewajski, Roman F.

doi:10.1007/s10910-010-9761-8

Cited by 33 publications

(41 citation statements)

References 35 publications

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“…9 [3,18]. As argued in the figure, the minimum (valence) basis set description of the bond structure in these two systems can be qualitatively understood in terms of the localized MO resulting from interactions between the directed (hybrid) orbitals on neighboring atoms, and the non-bonding electrons occupying the non-overlapping atomic hybrids.…”

Section: Local Probes Of Molecular Electron Distributionsmentioning

confidence: 95%

“…For example, this novel mechanism has been shown to have important implications for the bonding patterns of p-interactions in hydrocarbons [48,49]. The Hückel theory description of p-bonds in benzene predicts for the neighboring ortho-carbons a strong Wiberg bond multiplicity of almost exclusively through-space origin, while the crossring interactions, between the meta-and para-carbons, where shown to be described by smaller but practically equalized resultant bond-orders, being distinguished solely Fig.…”

Section: Indirect Chemical Interactionsmentioning

confidence: 97%

“…The chemical interaction between the specified pair of bonded atoms has recently been shown to exhibit both the direct (through-space) and, hitherto neglected, indirect (through-bridge) components resulting from the implicit dependencies between orbitals in the bond-subspace of the molecule [3,20,[48][49][50][51][52]. The former reflects the direct interactions/communications between AO, while the latter is realized indirectly, through the remaining basis functions which constitute an effective bridge for the implicit chemical coupling or the cascade probability scatterings between orbitals contributed by more distant atoms.…”

Section: Indirect Chemical Interactionsmentioning

confidence: 99%

“…However, even in these directly non-bonding cases, the chemical interaction between the specified (terminal) AO can still assume appreciable values, when the remaining atoms form an effective bridge of the neighboring, chemically bonded atoms, which links the two AO in question. The Wiberg-type indices for the indirect chemical bonds have been developed [3,48,49] and the molecular information channels for the indirect communications in the molecular bond system, involving a single or multiple sequential ''cascade'' of the remaining basis functions, have been established [3,52]. These indirect channels generate the associated bridge-contributions to the overall IT-covalency (communication-noise) and IT-ionicity (information-flow) bond descriptors, which together determine the entropic measure of the overall bridge-multiplicity of the chemical bond of interest.…”

Section: Indirect Chemical Interactionsmentioning

confidence: 99%

“…It is the main purpose of the next section to introduce the key concepts and techniques of IT which will be used in subsequent sections to illustrate some of the recent developments in alternative entropy/information probes of the molecular electronic structure and in OCT, the orbital formulation of the communication theory of the chemical bond (CTCB) [1]. The recently discovered mechanism of indirect chemical bonding [3,18,[48][49][50][51][52] will be also emphasized.…”

Section: Introductionmentioning

confidence: 99%

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Bond-order and entropic probes of the chemical bonds

Nalewajski

Gurdek

2012

Struct Chem

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An overview of the recent bond-order and entropy/information measures of the chemical bond multiplicity and of its covalent/ionic composition is given. The former include the Wiberg index of the molecular orbital (MO) theory and its atomic/diatomic components, while the latter explore the communication-noise (covalency) and information-flow (ionic) descriptors of molecular information channels in the atomic-orbital (AO) resolution. The illustrative application to the two-orbital model is presented and the atomic resolution of bond contributions is presented. Alternative information distributions, including densities of the displacement in the system Shannon entropy and its entropy deficiency relative to the ''promolecule,'' are advocated as effective probes of chemical bonds. They complement the familiar density difference diagrams of electron redistributions accompanying the bond formation process. These quantities are applied to investigate the central bond in small propellanes and the contragradience criterion, based upon the non-additive Fisher information in electron distribution, is shown to efficiently locate the bonding regions in butadiene and benzene. The novel, indirect bonding mechanism through the orbital intermediaries, inferred from the orbital communication theory in the AO resolution, is probed in these two illustrative p-electron systems using the generalized Wiberg bond-orders. It is shown to give rise to a more realistic representation of the second-neighbor interactions, which have previously been diagnosed as the direct (through-space) non-bonding. In MO theory, these through-bridge bond components are due to the implicit dependencies between the (non-orthogonal) AO projections onto the molecular bonding subspace of the occupied MO. They do not require the bond-charge accumulation between the nuclei of bonded atoms and can be realized at longer distances. The effective range of such indirect interactions is probed in representative polymers. Finally, the entropy/information concepts for three dependent probability distributions are used to qualitatively examine the promotion of reactants in catalysis. The chemisorbed species are predicted to undergo an ionic promotion, compared to the gas-phase reference, thus exhibiting more deterministic communications on the catalytic surface.

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Section: Local Probes Of Molecular Electron Distributionsmentioning

confidence: 95%

Section: Indirect Chemical Interactionsmentioning

confidence: 97%

Section: Indirect Chemical Interactionsmentioning

confidence: 99%

Section: Indirect Chemical Interactionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bond-order and entropic probes of the chemical bonds

Nalewajski

Gurdek

2012

Struct Chem

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Subsystem Communications and Electron Correlation

Nalewajski

2024

Electron Density

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Direct (through‐space) and indirect (through‐bridge) components of the chemical bond multiplicities

Nalewajski

2011

Int J of Quantum Chemistry

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It is argued that the chemical bond concept embodies all types of dependencies between general basis functions, called ' 'atomic orbitals' ' (AO), which are used to construct the bonding subspace of the occupied molecular orbitals (MOs), which in the single-determinant LCAO MO type approach fully describes the bonding pattern of a molecule. The chemical interaction between the specified AO can be both of the direct and indirect origin: the former results from the explicit dependency between the interacting AO, due to their constructive interference in a molecule, and the latter has its roots in the implicit dependencies between basis functions in the molecular bonding subspace. The indirect (throughbridge) contributions complement the familiar direct (through-space) bond-orders in the resultant pattern of bond multiplicities. The implicit components, realized via AO intermediates, are examined using the ' 'quadratic' ' Wiberg approach to the localized bond-orders and their information sources are investigated in the orbital communication theory of the chemical bond, in terms of the cascade communications between AO. The explicit and implicit dependencies between basis functions in the bonding subspace are linked to the relevant elements of the molecular charge-and-bond-order matrix. The conditional probabilities of the direct and bridge (cascade) probability propagations (' 'communications' ') between AO, which determine the associated molecular information channels, are derived and used to determine the information-theoretic (IT) bond descriptors. These entropy/information indices of the bond covalency and ionicity accordingly reflect the average ' 'noise' ' and the amount of the information flow in the molecular communications between AO. The multistage propagations involving full cascades of parallel AO bridges are shown to conserve the direct, stationary scattering probability between the given pair of terminal AO. This demonstrates the internal consistency of the bridge perspective on propagation of the electronic information in molecules. The associated Wiberg-type (quadratic) bond-order measures and IT bond multiplicities for these two types of interactions between AO are illustrated in the Hü ckel theory for selected p-electron systems (benzene, butadiene, and linear polyenes). In all these representative molecular systems, the resultant bond indices, combining the direct and indirect multiplicity contributions, are shown to generate a more balanced bonding perspective compared with the corresponding patterns resulting from the direct (Wiberg) bond-order approach alone. As illustrated for linear polyenes, the direct bonding can be realized at relatively short distances, while the indirect mechanism effectively extends the range of chemical interactions in molecular systems. The AO-resolved communications have been examined in a general basis set case, and the ' 'transition' ' communication system for the ' 'promolecule' ' ! molecule transformation has been proposed.

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Chemical bonds from through-bridge orbital communications in prototype molecular systems

Cited by 33 publications

References 35 publications

Bond-order and entropic probes of the chemical bonds

Bond-order and entropic probes of the chemical bonds

Subsystem Communications and Electron Correlation

Direct (through‐space) and indirect (through‐bridge) components of the chemical bond multiplicities

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