Experimental and theoretical study of lithium(1+) affinities of methyldiazoles

Alcamı́, Manuel; Mó, Otília; Yáñez, Manuel; Anvia, F.; Taft, R. W.

doi:10.1021/j100375a011

Cited by 41 publications

(23 citation statements)

References 2 publications

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“…The fact that neither 1CAl nor 2CAl is stable reflects that, as it has been shown for other bases, ,− the interactions with Al + although essentially electrostatic have a non-negligible covalent character. Although Al + is a closed shell system as are Li + and Na + , it has empty low-lying 3p orbitals which are accessible for a charge transfer from the base lone pair.…”

Section: Resultsmentioning

confidence: 82%

Acetamidine−X⁺and Guanidine−X⁺(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

et al. 1997

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The structures, harmonic vibrational frequencies, amino rotational barriers and binding energies of complexes formed by Li+, Na+, Mg+, and Al+ association to guanidine and acetamidine have been investigated by means of the B3LYP density functional approach. Both neutrals are predicted to be stronger bases than ammonia when the reference acids are the aforementioned metal cations. The basicity enhancement with respect to Mg+ and Al+ is only slightly smaller than that reported before when the reference acid is H+. Metal cation association leads to a significant increase in the corresponding amino rotational barriers and to sizeable shiftings of different vibrational modes, in particular those associated with the amino groups. For Li+ and Na+ complexes, the ion−neutral interactions are essentially electrostatic, while the bonds involving Al+ have a significant covalent character. For this reason the Al+ complexes closely resemble the corresponding protonated species. Mg+ represents an intermediate situation between alkali cations and Al+. The empty 3p orbitals of the metal cation play an important role in this respect.

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Section: Resultsmentioning

confidence: 82%

Acetamidine−X⁺and Guanidine−X⁺(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

et al. 1997

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“…Formation of the polymers by organolithium compounds [23][24][25] as well as by lithium phenolates [26] is a very common phenomenon. Different character of the sigma bonds formed between base and proton (polar covalent) and alkali metal cations (largely ionic) [27][28][29][30][31][32][33][34] are believed to be responsible for the differences observed in chelation of these species. As this can be seen (vide infera), the hitherto efforts were ineffective to show unequivocally the character of metal-oxygen interactions in lithium, sodium and potassium ortho-formyl(benzo)phenolates.…”

Section: Introductionmentioning

confidence: 99%

NMR studies of benzoannulation in lithium, sodium and potassium ortho-formylphenolates

Skotnicka

Kolehmainen

Laihia

et al. 2010

Journal of Molecular Structure

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“…The basicities so defined are generally describes as intrinsic basicities or, in general, intrinsic reactivities, because they are not masked by solvent effects. Often the neutrals exhibit unexpected gas-phase reactivities associated with the formation of nonclassical structures, , which will not be stable in the condensed phase, or with the fission of some chemical bonds of the base, as is the case of the dissociative proton attachment processes of fluoro- and chloroalkanes, which lead to the loss of XH (X = F,Cl) or the protonation of highly strained species, as tetraphosphacubane, which results in a partial breaking of the cubic structure of the neutral.…”

Section: Introductionmentioning

confidence: 99%

Protonation of S₄, S₆, and S₈Sulfur Cycles. A Quantitative Study

et al. 1998

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We have determined the gas-phase basicities of S 6 and S 8 by means of Fourier transform ion cyclotron resonance spectroscopy (FT-ICR): 167.8 and 187.1 kcal/mol, respectively. An ab initio investigation of the local minima of the S 6 H + potential energy surface shows that the most stable protonated species corresponds to a distorted five-membered ring structure rather than to a six-membered ring species. When the final energy of the aforementioned protonated species is evaluated at the G2(SVP,MP2) level, the agreement with the experimental value is very good. A G2(MP2) survey of the S 4 and S 4 H + potential energy surfaces shows that the most stable neutral and protonated species present cis open-chain structures. The relative stabilities of the different species investigated are extremely sensitive to electron correlation effects. At the G2(MP2) level S 4 is predicted to be slightly more basic than S 6 in the gas phase. Some preliminary ab initio calculations on the most probable structures of S 8 H + are also reported. Experimental SectionMaterials. S 8 . A highly pure sample of cyclooctasulfur (99.99%, Aldrich) was used. lts purity was assessed by means of its mass spectrum. S 6 . Cyclohexasulfur was obtained, according to Schmidt and co-workers, 12 by treating bis(cyclopentadienyl)titanium pentasulfide with sulfur dichloride in CS 2 at 0°C in the dark. The product was further crystallized from cold CS 2 in the dark, dried, and immediately subject to the FT-ICR study. Again, purity was assessed by means of the mass spectrum.FT-ICR Spectrometer. The instrument is a modified Bruker CMS 47 FT-ICR mass spectrometer 13 used in previous studies. [4][5][6][7][8]14,15 A detailed description of the main features of this instrument are given in refs 4, 13, and 14. The substantial field strength (4.7 T) of its supraconducting magnet allows the monitoring of ion-molecule reactions for relatively long periods of time.

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Experimental and theoretical study of lithium(1+) affinities of methyldiazoles

Cited by 41 publications

References 2 publications

Acetamidine−X⁺and Guanidine−X⁺(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

Acetamidine−X⁺and Guanidine−X⁺(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

NMR studies of benzoannulation in lithium, sodium and potassium ortho-formylphenolates

Protonation of S₄, S₆, and S₈Sulfur Cycles. A Quantitative Study

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Experimental and theoretical study of lithium(1+) affinities of methyldiazoles

Cited by 41 publications

References 2 publications

Acetamidine−X+and Guanidine−X+(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

Acetamidine−X+and Guanidine−X+(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

NMR studies of benzoannulation in lithium, sodium and potassium ortho-formylphenolates

Protonation of S4, S6, and S8Sulfur Cycles. A Quantitative Study

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Acetamidine−X⁺and Guanidine−X⁺(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

Acetamidine−X⁺and Guanidine−X⁺(X = Li, Na, Mg, Al) Complexes in the Gas-Phase. A Theoretical Study

Protonation of S₄, S₆, and S₈Sulfur Cycles. A Quantitative Study