[1.1.1]Propellane

Wiberg, Kenneth B.; Walker, Frederick H.

doi:10.1021/ja00383a046

Cited by 297 publications

(258 citation statements)

References 3 publications

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“…I tend to think, maybe in a simple minded way, that sulfur makes use of sp 3 hybrid orbitals for bonding and therefore there cannot be four two-electron bonds stemming from each S atom in A, but one should rather invoke delocalized bonding involving simultaneously the three metals and the opposing sulfur atom. During the discussion Roald pointed out that there is nothing wrong with having such a bonding pattern and referred to the topologically analogous [1.1.1]propellane, D. [13,14] I argue that the four short carbon distances from an apical carbon are not two-electron bonds, but a delocalized description of the bonding in that molecule is required, that includes occupation of an outward-pointing lone pair at the apical atoms and only three sp 3 hybrids of each bridgehead carbon atom can be used to form its four C À C "bonds". The presence of those lone pairs has been substantiated recently through an analysis of the electron localization function.…”

Section: Santiagomentioning

confidence: 97%

“…This would have been nothing new to Robert Mulliken, who has a well-known quote to that effect. 13 As we said at the outset, the presence or absence of a bond may be judged by several experimental and theoretical criteria. What was interesting in our discussion is how we moved from simple distance criteria to other gauges of bonding.…”

Section: Don't Think the [Aga C H T U N G T R E N N U N G (Olefin) 4 ]mentioning

confidence: 99%

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A Bonding Quandary—or—A Demonstration of the Fact That Scientists Are Not Born With Logic

Álvarez

Hoffmann

Mealli

2009

Chemistry A European J

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We document here a spirited debate among three colleagues and friends who have strong opinions on a specific bonding problem, the presence or absence of a cross-ring sulfur-sulfur bond in a trinuclear Cu(3)S(2) cluster. The example may seem esoteric, but through their struggles with this specific bond (and with each other) the authors approach the more general problematic of chemistry, the chemical bond. The discussion focuses on bond lengths and the population of bonding and antibonding orbitals, and on oxidation states, electron counting, and associated geometries. It expands to encompass other bonding criteria, and introduces examples ranging far across organic and inorganic chemistry. The authors suggest molecules that might test their ideas. An Appendix to the paper discusses a matter rarely broached in the chemical literature--should one review for publication a paper which criticizes one of your own contributions.

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Section: Santiagomentioning

confidence: 97%

Section: Don't Think the [Aga C H T U N G T R E N N U N G (Olefin) 4 ]mentioning

confidence: 99%

A Bonding Quandary—or—A Demonstration of the Fact That Scientists Are Not Born With Logic

Álvarez

Hoffmann

Mealli

2009

Chemistry A European J

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“…I lpropellane by Wiberg and Walker (17,18). Research has also been carried out on propellanes containing boron and heavier elements (Si, P, S, Sn, Ge) in bridge and (or) bridgehead positions (19,20).…”

Section: Propellanesmentioning

confidence: 99%

Quantum chemical valence indices from the one-determinantal difference approach

Nalewajski¹,

Mrozek²,

Mazur³

1996

Can. J. Chem.

134

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The recently introduced quadratic (two-electron) valence indices, ionic and covalent, derived from the HartreeFock finite-difference approach, are applied to selected organic and inorganic molecules to demonstrate their utility in monitoring chemical bonding patterns in molecular systems. The indices are defined in terms of differerences between simultaneous probabilities of finding two electrons on specified atoms, calculated from the molecular and separated-atomlimit (SAL) wave functions, respectively, in the UHF approximation. The total quadratic valence number represents the overall number of chemical bonds in the system under consideration; it is interpreted as the molecular expectation value of the difference operator of the molecular and SAL density operators. This interpretation leads to a new set of ionic atomic and diatomic valence components; these modified valence numbers are discussed using the two-orbital model in the UHF scheme. A new procedure is proposed for dividing the one-center contributions to the bond valences; it generates effective bond orders in qood agreement with chemical expectations. The new valence quantities are tested on selected typical molecules and prototype hydrogen-bonded dimers. A more extensive study has been canied out on small-ring propellanes, to examine changes in bond valences between bridgehead atoms in selected systems.

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“…Since the successful synthesis of [1.1.1] propellane by Wiberg and Walker, 1 numerous experimental 2, 3 and theoretical 4 studies have been devoted to understand the unusual structure and stability of this type of compounds. The remarkable stability of this propellane and related derivatives in spite of its considerable ring strain yields to these compounds new properties and potential applications in technological materials, which are being explored, such as molecular machines.…”

Section: Introductionmentioning

confidence: 99%

New insights on the bridge carbon–carbon bond in propellanes: A theoretical study based on the analysis of the electron localization function

2007

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The nature of the bonding between bridgehead carbon atoms (Ca, Ca') as well as the ring strain in a family of 10 propellanes formed by three-, four-, or five-member rings: [1.1.1] (I), [2.1.1] (II), [3.1.1] (III), [2.2.1] (IV), [3.2.1] (V), [2.2.2] (VI), [3.3.1] (VII), [3.2.2] (VIII), [3.3.2] (IX), and [3.3.3] (X) are studied by means of the electron localization function (ELF) at the DFT level (B3LYP/cc-pVTZ). The ELF analysis of smaller propellanes (I, II, and III) reveals the coexistence of two resonance forms: one with a nonbonding electron pair partially delocalized between Ca and Ca' atoms outside the cage (ionic) and the other with a bridge bond between the same atoms (covalent). The weights of each form are calculated according to the ELF-basin populations, yielding 94, 88, and 53% for the ionic structure of I, II, and III, respectively, while larger propellanes (IV-X) present only the covalent form. The question of the s-character of the bridge bond is addressed by dissecting the bridge-bond ELF basin into the molecular orbital contributions. Finally, sigma-aromaticity associated to surface electron delocalization has been analyzed by means of nucleus-independent chemical shift (NICS) calculations. The results point out that the stability of the fused ring structure of propellanes I, II, and III, can be assigned to the remarkable sigma-aromaticity of the involved three-member rings.

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[1.1.1]Propellane

Cited by 297 publications

References 3 publications

A Bonding Quandary—or—A Demonstration of the Fact That Scientists Are Not Born With Logic

A Bonding Quandary—or—A Demonstration of the Fact That Scientists Are Not Born With Logic

Quantum chemical valence indices from the one-determinantal difference approach

New insights on the bridge carbon–carbon bond in propellanes: A theoretical study based on the analysis of the electron localization function

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