Intensity of bands of the C≡C stretching modes in the IR spectra and conjugation in silylacetylenes

Egorochkin, A. N.; Skobeleva, S. E.; Mushtina, T. G.; Bogoradovsky, E.T.

doi:10.1007/bf02495350

Cited by 3 publications

(14 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, the Koopmans relationship is not rigorously fulfilled for ethylene derivatives as well as for substituted benzenes. 4 In this case the ene~,,y, of perturbation 8s determined using Eq. (16) characterizes the mixing of the orbitals in the radical cation rather than that of the orbitals of neutral molecules (as should be in the ease of rigorous fulfillment of the Koopmans relationship).…”

Section: Resultsmentioning

confidence: 99%

“…It is assumed that ts 7 = gl + ~R +-In the case of rigorous fulfilment of relation (2), a quantumchemical calculation of radical cation M" + can be performed using wa,ce functions of the neutral molecule M. However, as was established by the example of benzene derivatives, 4 intramo[ecular resonance interactions in M and M'* appreciably differ. This means that the conjugation between the R3E and Ph groups in neutral PhER 3 compounds is characterized by the crR~ resonance parameters, whereas that in radical cations, when the negative effective charge on ~he Ph group is subsumtially decreased, is characterized by the ~R + parameters, 4 In the studies of ethylene derivatives R3ECH=CH2 we met conven6onal conditions for studying thte conjugation in R3EP~. molecules by analyzing the 1~ values: a common indicator center R.=.…”

Section: Procedures Of Calculationsmentioning

confidence: 99%

See 1 more Smart Citation

First ionization potentials and conjugation in molecules of ethylene derivatives containing organoelemental substituents of Group IV elements

1997

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Procedures Of Calculationsmentioning

confidence: 99%

First ionization potentials and conjugation in molecules of ethylene derivatives containing organoelemental substituents of Group IV elements

1997

Self Cite

View full text Add to dashboard Cite

show abstract

“…Until recently, + R values for organometallic substituents (which are arbitrarily referred to as primary) were known only for phenyl and benzyl derivatives (D = Ph, Table 1) which were extensively studied by chemical and spectral methods [1,2]. The corresponding values for other D became accessible only as a result of our studies [3][4][5][6][7][8][9] ( Table 1). Let us consider general relations holding in variation of + R for MMe 3 and CH 2 MMe 3 , depending on the nature of M and D.…”

mentioning

confidence: 97%

“…We are now capable of studying donor resonance effect in derivatives with D other than Ph. This is favored by accumulation of data (though poorly analyzed) on resonance effects in radical cations Me 3 MD + · and Me 3 MCH 2 D + · [3][4][5][6][7][8][9] having a large positive charge on various D centers. We anticipated that study of such radical cations will make it possible to analyze donor effects of , and ,n conjugation (which are the main factor responsible for nongeneral character of resonance parameters of organometallic substituents) provided that acceptor effects of d, and d,n conjugation (in Me 3 SnD + · ) or *, and *,n conjugation (in Me 3 MCH 2 D + · ) are less important.…”

mentioning

confidence: 99%

“…Conjugation in molecules like DMMe 3 and DCH 2 MMe 3 (M = Si, Ge, Sn) which possess a large positive charge on the D center (e.g., in radical cations Me 3 MD + · and Me 3 MCH 2 D + · ) is quantitatively characterized by electrophilic resonance parameters + R of MMe 3 and CH 2 MMe 3 substituents [1][2][3][4][5][6][7][8][9]. Until recently, + R values for organometallic substituents (which are arbitrarily referred to as primary) were known only for phenyl and benzyl derivatives (D = Ph, Table 1) which were extensively studied by chemical and spectral methods [1,2].…”

mentioning

confidence: 99%

See 1 more Smart Citation

Nongeneral Character of the Resonance Parameters Σ R + of Silicon-, Germanium-, and Tin-Containing Substituents in Radical Cations

Egorochkin

Кузнецова

2005

Russ J Org Chem

Self Cite

View full text Add to dashboard Cite

The resonance parameters + R of substituents Y in radical cations YD + · [where D is a -or n-type center, and Y = MMe 3 , CH 2 MMe 3 (M = Si, Ge, Sn), C(SiMe 3 ) 3 ] depend on the nature of both Y and D. Using radical cations YD + · (Y = CH 2 SiMe 3 , SnMe 3 ) as examples, it was found that the two conjugation parameters, constants + R of substituents Y and perturbation energy calculated by the modified molecular orbital perturbation method, are linearly related to each other. The energies of donor and acceptor components of the overall resonance effect of CH 2 SiMe 3 and SnMe 3 with respect to radical cation centers D + · were estimated for the first time. The donor energy constituent in YD + · is considerably greater than in neutral DY molecules.In keeping with the modern views [1, 2], conjugation in DMMe 3 and DCH 2 MMe 3 molecules is determined by properties of both MMe 3 or CH 2 MMe 3 substituent (M = Si, Ge, Sn) and reaction center D; the latter may be an , -unsaturated or aromatic hydrocarbon radical (R ), as well as an atom (X) possessing unshared electron pairs. Therefore, the ability of substituents like MMe 3 and CH 2 MMe 3 to be involved in conjugation with D cannot be described by universal resonance parameters like R which are invariant from D. The absence of universality is closely related to the mechanism of conjugation in molecules like DMMe 3 and DCH 2 MMe 3 , which is more complex than in analogous carbon derivatives (M = C).The mechanism of conjugation is based on the concept involving dual (acceptor and donor simultaneously) resonance properties of MMe 3 substituents (M = Si, Ge, Sn) with respect to D in DMMe 3 molecules [1,2]. Acceptor resonance effect (d, or d,n conjugation) implies interaction between vacant nd orbitals of atoms M and antibonding * orbitals of the M-C bonds in MMe 3 , on the one hand, and R group (or X atom), on the other. This effect becomes weaker as the atomic number of M rises in the series Si > Ge > Sn; when M = C, acceptor resonance effect is absent. Donor resonance effect ( , or ,n conjugation) is interaction between orbitals of the M-C bond in MMe 3 and R group (or X atom), and it becomes stronger as the atomic number of M rises (C < Si < Ge < Sn); i.e., the effect is minimal for M = C.The CH 2 MMe 3 substituents in DCH 2 MMe 3 molecules act as weak acceptors and strong donors with respect to D [1]. Clearly predominating donor resonance effect of , and ,n conjugation originates from interaction between orbitals of the C-M bonds in CH 2 MMe 3 and R group (or X) [1, 2]. As with MMe 3 , the effect increases in the M series C < Si < Ge < Sn.Weak and poorly studied [1] acceptor resonance effect of CH 2 MMe 3 substituents originates from *, (or *,n) conjugation, i.e., interaction between antibonding * orbitals of the CH 2 -M bond and R (or X). It will be shown below that effects of *, and *,n conjugation in DCH 2 MMe 3 , despite their lesser importance as compared to donor , and ,n conjugation, are not negligible. Of the two opposite constituents of the overall resonance...

show abstract

Electron-rich Fe(ii) and Fe(iii) organoiron σ-alkynyl complexes bearing a functional aryl group. Vibrational spectroscopic investigations of the substituent effect on the CC triple bond

Paul

Mevellec

Lapinte

2002

J. Chem. Soc., Dalton Trans.

View full text Add to dashboard Cite

Intensity of bands of the C≡C stretching modes in the IR spectra and conjugation in silylacetylenes

Cited by 3 publications

References 13 publications

First ionization potentials and conjugation in molecules of ethylene derivatives containing organoelemental substituents of Group IV elements

First ionization potentials and conjugation in molecules of ethylene derivatives containing organoelemental substituents of Group IV elements

Nongeneral Character of the Resonance Parameters Σ R + of Silicon-, Germanium-, and Tin-Containing Substituents in Radical Cations

Electron-rich Fe(ii) and Fe(iii) organoiron σ-alkynyl complexes bearing a functional aryl group. Vibrational spectroscopic investigations of the substituent effect on the CC triple bond

Contact Info

Product

Resources

About