Topic
Steric effects
About: Steric effects is a research topic. Over the lifetime, 16112 publications have been published within this topic receiving 319615 citations. The topic is also known as: steric hindrance.
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TL;DR: In this paper, the C-C bond length of di-t-butylmethane was found to be 1.534 ± 0.005 A from the neopentane reference value.
72 citations
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TL;DR: The results of experiments allow the identification of particular absorption bands in the 11-cis-retinal spectrum, which are steric hindrance and bend in the system of conjugated double bonds.
Abstract: THE absorption spectrum of 11-cis-retinal is strongly influenced by the presence of a cis bond between carbon atoms 11 and 12. The cis bond in this position results in two important spatial properties of the molecule: first, steric hindrance between the C13-methyl group and the C10-hydrogen atom; second, a bend in the system of conjugated double bonds. Both the steric hindrance and the bend in the molecule give rise to particular absorption bands. We now report the results of experiments which allow the identification of these absorption bands in the 11-cis-retinal spectrum.
71 citations
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TL;DR: The spirohydantoin (α-isomer) obtained from 4-tert-butylcyclohexanone by the Bucherer-Bergs reaction has been shown by as mentioned in this paper.
Abstract: The spirohydantoin (α-isomer) obtained from 4-tert-butylcyclohexanone by the Bucherer–Bergs reaction has been shown by n.m.r., u.v., and considerations of steric hindrance to have the tert-butyl gr...
71 citations
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TL;DR: Fundamental model compounds for the Hammett equation, meta- and para-substituted benzoic acids, were investigated by the density functional theory at the B3LYP/6-311+G(d,p) level and relative acidities correlated with the experimental gas-phase acidities almost within the experimental uncertainty.
Abstract: Fundamental model compounds for the Hammett equation, meta- and para-substituted benzoic acids, were investigated by the density functional theory at the B3LYP/6-311+G(d,p) level. Energies of 25 acids and of their anions were calculated in all possible conformations and from them the energies of the assumed mixture of conformers. Relative acidities correlated with the experimental gas-phase acidities almost within the experimental uncertainty, much more precisely than in the case of previous calculations at lower levels. Dissection of the substituent effects into those operating in the acid molecule and in the anion was carried out by means of isodesmic reactions starting from monosubstituted benzenes. Both effects are cooperating in the resulting effect on the acidity; those in the acid molecule are smaller but not negligible. They are also responsible for some deviations from the Hammett equation (through-resonance of para donor substituents) and for the weaker resonance in the acid molecule in meta derivatives; in the anions the inductive and resonance effects are almost equal. On the other hand, the cooperation of effects in the acid and in the anion makes the relative acidity more sensitive to electron withdrawing and is probably one of the reasons why the Hammett equation is so generally valid.
71 citations
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TL;DR: In this article, the electron donating abilities of naphthyl and anthracenyl phosphine ligands has been explored using gas phase photoelectron spectral data on the parent phosphines and their relative complexing ability to platinum precursor molecules has been assessed by means of synthetic studies and NMR experiments.
71 citations