A comparison of the energies of double bonds of second-row elements with carbon and silicon

Schleyer, Paul v. R.; Kost, Daniel

doi:10.1021/ja00215a016

Cited by 215 publications

(141 citation statements)

References 2 publications

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“…The energy of the π bond has been estimated [54] at the MP4(SDTQ) 6Ϫ31(d) level for the three parent compounds H 2 SiϭNH (37.0 kcal·mol Ϫ1 ), H 2 SiϭPH (29.7 kcal·mol Ϫ1 ) and H 2 SiϭS (43.6 kcal·mol Ϫ1 ), and we found the same order from the values observed for the ionizations associated with the ejection of a π bond electron. The authors [54] proposed a correlation between the π bond energy and the electronegativity of the X atom (P: 2.1, S: 2.5, N: 3.0).…”

Section: Photoelectron Spectrometry ؊ Theoretical Resultssupporting

confidence: 78%

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Flash Vacuum Thermolysis Synthesis of New Reactive Compounds Containing a Silicon−Heteroatom Double Bond

2000

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Section: Photoelectron Spectrometry ؊ Theoretical Resultssupporting

confidence: 78%

“…The authors [54] proposed a correlation between the π bond energy and the electronegativity of the X atom (P: 2.1, S: 2.5, N: 3.0).…”

Section: Photoelectron Spectrometry ؊ Theoretical Resultsmentioning

confidence: 99%

Flash Vacuum Thermolysis Synthesis of New Reactive Compounds Containing a Silicon−Heteroatom Double Bond

2000

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“…Table 2 contains the p-bond energies of Gordon et al [9] and Schleyer et al [11] along with the computed and average [according to Eq. (1 a)] BOVB values.…”

Section: Resultsmentioning

confidence: 99%

“…Gordon et al [9] found p-bond energies by both rotation barriers and the previously discussed hydrogenation reaction for H m A BH n molecules, where A, B C, N, O, Si, P, S. Estimates of p-bond energies obtained with the two methods differ by as much as 9 kcal mol À1 in the case of HNNH. Using isodesmic reactions, Schleyer and Kost [11] obtained p-bond energies for H m A BH n molecules, where A C, Si and B C, N, O, Si, P, S which were generally greater than those of Gordon et al [9] by as much as 16 kcal mol À1 for H 2 CO. Notable also is the disparity with the values of Kutzelnigg [12] which were obtained through evaluation of experimental thermodynamical data.…”

Section: Abstract In Hebrewmentioning

confidence: 95%

π Bonding in Second and Third Row Molecules: Testing the Strength of Linus's Blanket

et al. 2000

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The flexibility of valence bond (VB) theory provides a new method of calculating pi-bond energies in the double-bonded species H(m)A=BH(n), where A, B = C, N, O, Si, P, S. This new method circumvents the problems usually associated with obtaining pi-bond strengths by targeting only the pi bond, while all other factors remain constant. In this manner, a clean separation between sigma- and pi effects can be achieved which highlights some expected trends in bond strength upon moving from left to right and up and down the Periodic Table. Intra-row pi bonds conform to the classic statement by Pauling [L. Pauling, The Natiure of the Chemical Bond, Cornell University Press, Ithaca, 1960, 3rd edition] regarding the relationship of heteronuclear bond strengths to their homonuclear constituents whereas inter-row pi bonds do not. This variance with Pauling's statement is shown to be due to the constraining effect of the underlying sigma bonds which prevents optimal p(pi)-p(pi) overlap. While Pauling's statement was based on the assumption that the resonance energy (RE) would be large for heteronuclear and small for homonuclear bonds, we have found large REs for all bonds studied herein; this leads to the conclusion that REs are dependent not only on the electronegativity difference but also the electronegativity sum of the constituent atoms. This situation where the bond is neither covalent nor ionic but originates in the covalent-ionic mixing has been termed charge shift (CS) bonding [S. Shaik, P. Maitre, G. Sini, P. C. Hiberty, J. Am. Chem. Soc. 1992, 114, 7861]. We have shown that CS bonding extends beyond single sigma bonds in first row molecules, thus supporting the idea that CS-bonding is a ubiquitous bonding form.

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“…Phosphanickelocenes bridised phosphorus centres such as phosphinines, [28][29][30] phosphaalkynes [31,32] or phosphaalkenes, [33,34] and other phosphametallocenes. [35][36][37] However, they remain high with respect to classical phosphines [38] so that the phosphorus centre must be characterised as weakly basic.…”

Section: Full Papermentioning

confidence: 99%

Synthesis and Properties of [NiCp*(2,5‐tBu₂PC₄H₂)], a 20‐Valence‐Electron Phosphanickelocene

Burney

Carmichael

Forissier

et al. 2005

Chemistry A European J

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The reaction of the bulky phospholide salt Li(2,5-tBu2PC4H2) x 2THF (1; THF = tetrahydrofuran) with [NiCp*(acac)] (HCp* = pentamethylcyclopentadiene, Hacac = acetylacetone) gives the green air-sensitive phosphanickelocene [NiCp*(2,5-tBu2PC4H2)] (2) in yields of about 85%. An X-ray structural determination of 2 shows long Ni-ring bonds and "delocalised" ring P-C and C-C bonds characteristic of a classical 20-valence-electron (ve) nickelocene. The electronic structure of 2 has been clarified through a combined Amsterdam density functional (ADF) and photoelectron spectroscopic study, which indicates that the higher lying semi-occupied molecular orbital (SOMO) (-5.82 eV) has a' symmetry and that the phosphorus "lone pair" is energetically low-lying (-8.15 eV). Oxidation of phosphanickelocene 2 by AgBF4 occurs quantitatively to give the corresponding air-sensitive orange phosphanickelocenium salt [NiCp*(2,5-tBu2PC4H2)][BF4] (3). This complex has also been characterised by an X-ray crystallographic study, which reveals long Ni-C(alpha) and short C(alpha)-C(beta) bonds in the phospholyl ligand indicative of a SOMO having a'' symmetry. PMe3 reacts with 2 at room temperature to provoke a ring-slip reaction that gives the 18ve complex [NiCp*eta1-(2,5-tBu2PC4H2)(PMe3)] (4), but shows no reaction with the phosphanickelocenium salt 3 under the same conditions.

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A comparison of the energies of double bonds of second-row elements with carbon and silicon

Cited by 215 publications

References 2 publications

Flash Vacuum Thermolysis Synthesis of New Reactive Compounds Containing a Silicon−Heteroatom Double Bond

Flash Vacuum Thermolysis Synthesis of New Reactive Compounds Containing a Silicon−Heteroatom Double Bond

π Bonding in Second and Third Row Molecules: Testing the Strength of Linus's Blanket

Synthesis and Properties of [NiCp*(2,5‐tBu₂PC₄H₂)], a 20‐Valence‐Electron Phosphanickelocene

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A comparison of the energies of double bonds of second-row elements with carbon and silicon

Cited by 215 publications

References 2 publications

Flash Vacuum Thermolysis Synthesis of New Reactive Compounds Containing a Silicon−Heteroatom Double Bond

Flash Vacuum Thermolysis Synthesis of New Reactive Compounds Containing a Silicon−Heteroatom Double Bond

π Bonding in Second and Third Row Molecules: Testing the Strength of Linus's Blanket

Synthesis and Properties of [NiCp*(2,5‐tBu2PC4H2)], a 20‐Valence‐Electron Phosphanickelocene

Contact Info

Product

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Synthesis and Properties of [NiCp*(2,5‐tBu₂PC₄H₂)], a 20‐Valence‐Electron Phosphanickelocene