Hydrogen Exchange in Benzyl Methyl Sulfoxide. Kinetic and Spectroscopic Nonequivalence of Methylene Protons

Rauk, Arvi; Buncel, Erwin; Moir, R. Y.; Wolfe, Saul

doi:10.1021/ja00951a050

Cited by 63 publications

(17 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Examples exist (57) in which racemic and optically active forms of the same complex under identical conditions display different kinetic behavior. Also, methylbenzyl sulfoxide shows two apparent coalescence temperatures for the diastereotopic benzylmethylene protons, and yet the sulfur center is stable to inversion (58). Here, temperature-dependent chemical shifts and perhaps sulfoxide association are complicating factors.…”

Section: Co Rmentioning

confidence: 99%

Rearrangement in Coordination Complexes

Jackson¹,

Sargeson²

1980

Organic Chemistry: A Series of Monographs

View full text Add to dashboard Cite

Section: Co Rmentioning

confidence: 99%

Rearrangement in Coordination Complexes

Jackson¹,

Sargeson²

1980

Organic Chemistry: A Series of Monographs

View full text Add to dashboard Cite

“…The relevance of d orbital conjugation to ground state properties of organosulfur compounds has been challenged on the basis of molecular orbital f If PhS0 2 GH 2 C(CH3)3 is used as a reference point, the acidifying effects from Table 2.3 expressed as ΔρΚ for (CH 3 ) 3 N + , P h S 0 2 , CN,COPh,and N O a are 11.8,19,19.2,19.8,and 24.1,respectively. calculations by Wolfe and co-workers (Wolfe et al, 1967(Wolfe et al, , 1970Rauk et al, 1965Rauk et al, , 1969Bernardi et al, 1975;Epiotis et al, 1976), Coulson (1969), Florey and Cusachs ( 1972), Musher ( 1972), Streitweiser and Williams (1975), and Lehn and Wipff (1976). For example, ab initio S C F -M O calculations on R S C H 2 -, R O C H 2 -, and R C H 2 C H 2 -(R = H or CH 3 ) predict the order of gas phase carbanion stabilization as S > O > C whether or not sulfur 3d orbitals are used in the calculations.…”

Section: -15mentioning

confidence: 99%

“…The diamagnetic anisotropy of the sulfoxide group results in the nonequivalence of these α-methylene protons in NMR spectra ; peak separation can generally be improved by addition of shift reagents or benzene (Barbarella et al, 1975 and references therein). The first evidence for the differential acidity of diastereotopic a-methylene protons such as H A and H B in 2-23 was provided in 1965 by Rauk and co-workers who demonstrated that one of the protons in 2-23 (later shown to be the pro-R hydrogen H A ) undergoes exchange in D 2 0/NaOD at a rate approxi mately 16 times faster than the other (H B or pro-S hydrogen) (Rauk et al, 1965; also see Baldwin et al, 1969 andViau, 1973). The basis for proton exchange in sulfoxides with retention and inversion of configuration was examined by molecular orbital calculations on the hypothetical anion -CH 2 S(0)H .…”

Section: Stereochemical Aspects Of α-Sulfinyl Carbanionsmentioning

confidence: 99%

Sulfur-Containing Carbanions

1978

Organic Chemistry: A Series of Monographs

View full text Add to dashboard Cite

“…Our primary interest is in the sulfinyl grouping (10). Because even the simplest sulfoxide, H,SO (I), represents a 26-electron problem containing four atoms, it was clear at the outset that a minimal basis set of G.t.f.…”

Section: Introductionmentioning

confidence: 99%

Nonempirical s.c.f. calculations on sulfur atom, hydrogen sulfide, and dihydrogen sulfoxide

Rauk¹,

Csizmadia²

1968

Can. J. Chem.

Self Cite

View full text Add to dashboard Cite

This paper reports the f i s t attempt to use Gaussian basis sets in nonempirical self-consistent field (s.c.f.) calculations on sulfur-containingchemical systems. Exponents for Gaussian-type functions (G.t.f.) on S atom are given for the minimal basis set. The optimization procedure is described and the optimized exponents utilized on calculations on S atom, H2S, and the hypothetical dihydrogen sulfoxide (H2SO). Calculations by the minimal basis set of G.t.f., using these exponents, gave a value for the HSH angle of H2S that agrees well with the experimentally determined value. Calculations of H,SO support a "multiple bond" picture of the S-0 bond.Canadian Journal of Chemistry, 46, 1205Chemistry, 46, (1968 Introduction Ab initio calculations on atoms and small molecules are well established in the chemical literature (1). Accurate results have been obtained usingexponential-type functions (e.t.f.) or, as usually referred to, Slater-type orbitals (S.t.0.) as basis functions in the s.c.f. procedure. Satisfactory results have also been obtained using Gaussian-type functions (G.t.f.) or, as sometimes called, Gaussian-type orbitals (G.t.o.), when the basis set size is approximately 2 to 3 times as large as the equivalent basis set of e.t.f. (2). Methane, as a classical example, may be quoted for comparison of the numerical results obtained from e.t.f. and G.t.f. basis sets (3)(4)(5)(6)(7)(8). These results are shown in Table I. A compendium of ab initio calculations covering the period of 1960-67 which includes results of both e.t.f. and G.t.f. calculations has been prepared (9). Because it is possible to compute integrals over a basis of G.t.f. about 1000 times faster than over e.t.f., it appears advantageous to use the former, especially when the number of electrons in the problem becomes large. Even with this device it may still be necessary to employ a basis set that is less than adequate for quantitative purposes.Our primary interest is in the sulfinyl grouping (10). Because even the simplest sulfoxide, H,SO (I), represents a 26-electron problem containing four atoms, it was clear at the outset that a minimal basis set of G.t.f. had to be utilized. Exponents for the S atom were unknown because no S-containing compounds had been previously treated with G.t.f. It was necessary therefore to obtain first an optimal set of exponents for stype and p-type functions from open shell s.c.f. calculations on S atom in its electronic ground (3P) state and the exponent for d-type functions from closed shell s.c.f. calculations on H,S. This paper reports these results. To complete this preliminary study we have also performed closed shell s.c.f. calculations on 1.The mathematical formalism for the open and closed shell s.c.f. as well as other calculations (dipole moment, population analysis, and electron density contour plots) have been reviewed recently (11) 46, 1968 results obtained from computations on S, H2S, and H 2 S 0 are given in this paper. The computations have been carried out on an IBM 7094-11 computer usin...

show abstract

Hydrogen Exchange in Benzyl Methyl Sulfoxide. Kinetic and Spectroscopic Nonequivalence of Methylene Protons

Cited by 63 publications

References 0 publications

Rearrangement in Coordination Complexes

Rearrangement in Coordination Complexes

Sulfur-Containing Carbanions

Nonempirical s.c.f. calculations on sulfur atom, hydrogen sulfide, and dihydrogen sulfoxide

Contact Info

Product

Resources

About