Stable Pentacoordinate Carbocations: Structure and Bonding

Fernández, Israel; Uggerud, Einar; Frenking, Gernot

doi:10.1002/chem.200700744

Cited by 34 publications

(29 citation statements)

References 50 publications

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“…Theoretical works (Jemmis et al, 1979;Ferná ndez et al, 2007) have shown the stability of penta-coordinated carbenium ions and other cations containing more electropositive elements than carbon (Be and Group 13 and 14 elements) and whose bonding scheme also fits to a (2e, 3c) bond.…”

Section: Introductionmentioning

confidence: 97%

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Vegas

Notario

Chamorro

et al. 2013

Acta Crystallogr Sect B

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A topological analysis of the electron localization function (ELF) of a molecule of hexamethyldisiloxane, (H 3 C) 3 -Si-OSi-(CH 3 ) 3 , has been carried out, drawing a consistent picture of Si-O-Si bonding both in the linear and angular geometries. The ELF analysis confirms the idea that the O atom, in the linear geometry of (H 3 C) 3 -Si-O-Si-(CH 3 ) 3 , is isolobal with the isoelectronic -CH þ 3 -and -BH 3 -groups, the bonding in the Si-O-Si group being described as a two-electron, three-center (2e, 3c) bond. At the same time, the three oxygen lone pairs mirror the three C-H and B-H bonds, respectively. On the contrary, in the angular geometry the same O atoms form two Si-O bonds and its lone pairs mimic the geometry of the -CH 2 -group. In this model the O atoms would play the same role as the formally present O 2À anions in the 'so-called' ionic solids, such as in the skeletons of aluminate and silicate polyanions, thereby connecting molecular and solid-state chemistry as formulated by the 'fragment formalism' or the 'molecular unit-cell approach'. This unifying concept as well as the calculations we have carried out fully agree and also give support to earlier ideas developed by Bragg and Bent, among other authors. Bonding in the series of compounds P 4 , P 4 O 6 , P 4 O 10 , N 4 (CH 2 ) 6 (hexamethylenetetramine) and (CH) 4 (CH 2 ) 6 (adamantane) is discussed in the context of the isolobal model.

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Section: Introductionmentioning

confidence: 97%

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Vegas

Notario

Chamorro

et al. 2013

Acta Crystallogr Sect B

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“…It is worth mentioning that inspired in this study showing the stabilization of the Si 2 (CH 3 ) 7 + ion through the contribution of threecenter-two-electron bonds, it was predicted, on theoretical grounds, that a similar stabilization occurs for the Ge, Sn and Pb containing analogues [71]. Based on the fact that the structure predicted for the Si 2 (CH 3 ) 7 + ion in ref.…”

Section: Pentacovalent Carbon Atomsmentioning

confidence: 65%

“…Based on the fact that the structure predicted for the Si 2 (CH 3 ) 7 + ion in ref. The theoretical study carried out by Fernández, Uggerud and Frenking [71] actually confirmed that the X 2 Me 7 + (X = Ge, Sn, Pb) ions also present a D 3h structure with a planar CH 3 group symmetrically bonded to two XMe 3 moieties. Hence, very likely, systems in which the SiMe 3 nucleophile is replaced by other electropositive groups, XMe 3 (X = Ge, Sn and Pb), will yield also X 2 Me 7 + stable species.…”

Section: Pentacovalent Carbon Atomsmentioning

confidence: 81%

Unexpected Gas-Phase Ion Chemistry Results Unraveled by Computational Chemistry

Gámez¹,

Corral²,

Mó³

et al. 2010

COC

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An overview of recent studies, which show the important role played by computational chemistry in explaining and predicting the behavior of a great variety of systems is presented. The first example illustrates the useful interplay experiment-theory which allowed to unambiguously characterize the X2(CH3)7 + (X = Si, Ge, Sn, Pb) cations as paradigmatic examples of molecular systems involving pentacovalently bound carbon atoms. Also, the possibility of deeply analyzing the bonding in molecular systems, led to a rationalization of the quite different behavior of acetylene and iminoborane derivatives, in spite of being isoelectronic species. Similarly, the analysis of the bonding perturbations usually associated with ion-molecule interactions in the gas phase, or with protonation and deprotonation processes, has made possible the characterization of non-conventional complexes as the key structures in the interactions of unsaturated and aromatic Si and Ge containing compounds with transition metal ions or to explain the dramatic enhanced acidity of alkylboranes and ,unsaturated borane derivatives.

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“…As the central C atom (CH þ 3 cation) has only three valence electrons, shared with the H atoms, the C and the two Si atoms must form a two-electron, three-center bond (Dá valos et al, 2007). Theoretical works (Jemmis et al, 1979;Ferná ndez et al, 2007) have shown the stability of penta-coordinated carbenium ions and other cations containing more electropositive elements than carbon (Be and Group 13 and 14 elements) and whose bonding scheme also fits to a (2e, 3c) bond.…”

Section: Siðch 3 þ þmentioning

confidence: 99%

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Vegas

Notario

Chamorro

et al. 2013

Acta Crystallogr Sect B

View full text Add to dashboard Cite

A topological analysis of the electron localization function (ELF) of a molecule of hexamethyldisiloxane, (H3C)3-Si-O-Si-(CH3)3, has been carried out, drawing a consistent picture of Si-O-Si bonding both in the linear and angular geometries. The ELF analysis confirms the idea that the O atom, in the linear geometry of (H3C)3-Si-O-Si-(CH3)3, is isolobal with the isoelectronic -CH3(+)- and -BH3- groups, the bonding in the Si-O-Si group being described as a two-electron, three-center (2e, 3c) bond. At the same time, the three oxygen lone pairs mirror the three C-H and B-H bonds, respectively. On the contrary, in the angular geometry the same O atoms form two Si-O bonds and its lone pairs mimic the geometry of the -CH2- group. In this model the O atoms would play the same role as the formally present O(2-) anions in the `so-called' ionic solids, such as in the skeletons of aluminate and silicate polyanions, thereby connecting molecular and solid-state chemistry as formulated by the `fragment formalism' or the `molecular unit-cell approach'. This unifying concept as well as the calculations we have carried out fully agree and also give support to earlier ideas developed by Bragg and Bent, among other authors. Bonding in the series of compounds P4, P4O6, P4O10, N4(CH2)6 (hexamethylenetetramine) and (CH)4(CH2)6 (adamantane) is discussed in the context of the isolobal model.

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Stable Pentacoordinate Carbocations: Structure and Bonding

Cited by 34 publications

References 50 publications

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Unexpected Gas-Phase Ion Chemistry Results Unraveled by Computational Chemistry

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

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Stable Pentacoordinate Carbocations: Structure and Bonding

Cited by 34 publications

References 50 publications

Isoelectronic and isolobal O, CH2, CH3+and BH3as electron pairs; similarities between molecular and solid-state chemistry

Isoelectronic and isolobal O, CH2, CH3+and BH3as electron pairs; similarities between molecular and solid-state chemistry

Unexpected Gas-Phase Ion Chemistry Results Unraveled by Computational Chemistry

Isoelectronic and isolobal O, CH2, CH3+and BH3as electron pairs; similarities between molecular and solid-state chemistry

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Product

Resources

About

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry

Isoelectronic and isolobal O, CH₂, CH₃⁺and BH₃as electron pairs; similarities between molecular and solid-state chemistry