Controversy in Chemistry: What Counts as Evidence?—Two Studies in Molecular Structure

Labinger, Jay A.; Weininger, Steve J.

doi:10.1002/anie.200330055

Cited by 14 publications

(5 citation statements)

References 54 publications

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“…The most important action for us to take is to admit our own errors as soon as we discover the correct answers. For another recent essay on controversy in chemistry, see the article by Labinger and Weininger 70…”

Section: Resultsmentioning

confidence: 99%

Synthetic examination of incorrectly proposed structures of biomolecules

Mori

2005

Chem. Record

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Many incorrect structures of biomolecules have been proposed for natural products. Synthesis of compounds having the proposed structures often enabled us to judge the correctness of the proposals. In some cases, we were able to revise the structures by synthesizing the biomolecules themselves. In other cases, we were able to definitely disprove the proposed structures. Some examples treated in this review include: auxin-a and b; the sex pheromone of Chlamydomonas; sex pheromones of the gypsy moth, the American cockroach, and the pink bollworm moth; Persoons' periplanone-A; orobanchol; naurol A; bifurcarenone; koninginin A; alpha-acoradiene; himachalene-type pheromones of the flea beetle; differolide; blattellastanoside A and B; etc.

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Section: Resultsmentioning

confidence: 99%

Synthetic examination of incorrectly proposed structures of biomolecules

Mori

2005

Chem. Record

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“…Falsification of empirical theories may take a long time and become so complicated that participants just drop out, get tired, or lack funding. Chemistry might be typical for a science which develops in a rather Darwinian process, relying not only on socioeconomic conditions but also on personal judgment …”

Section: Discussionmentioning

confidence: 99%

The controversy about nonclassical ions: Finished too early?

Schneider

2018

J of Physical Organic Chem

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The debate on nonclassical ions centered almost exclusively on the behavior of 2norbornyl esters. The hallmark of a nonclassical charge distribution in solvolysis reactions was always seen in the seemingly exceptional fast reaction of the 2-exoderivatives, with slow rates of the endo-esters. While the nonclassical bridged structure of the free norbornyl ion has been unequivocally established, possible steric contributions to the rate differences in solution remained a matter of debate. Many formerly used solvents were less suited to exhibit uniform reaction mechanisms; the most appropriate solvent hexafluorisopropanol was introduced rather late. Solvolysis rates of many cyclic esters including medium rings can be predicted by force field calculated strain energy differences ΔSI sp3/sp2 between sp 3 and sp 2 states. Large deviations from the correlation are observed for 2-tosyloxy norbornane-and for 17-tosyloxy steroids; they indicate that both nonclassical charge delocalization and steric hindrance play a major role for the reactivity differences. These reach an unprecedented rate constant ratio of >30.000 between, eg, the 17-steroid epimers, much larger than the ratio of 1.550 in 2-norbornyl reactions. The presence of alkyl groups or hydrogen antiperiplanar to the leaving group can lead to extreme reactivities by 1,2-shifts or Wagner-Meerwein rearrangement if asymmetric bridged transition states can occur which approach the stability of tertiary cations.The long controversy about nonclassical ions illustrates how progress in science can deviate significantly from the ideal pathways lined out by Karl Popper.

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“…The underlying cause for the coordination chemical flexibility manifest in compound 3 is an angular Jahn–Teller distortion at the iron centre 11. On a historical note, compound 3 presents a case of spin‐state isomerism ( 3a vs. 3b‐ls ),35,36 and at the same time is a true example of distortional isomerism ( 3a vs. 3b‐hs ), the latter being related to “bond‐stretch isomerism” which, at least in the context of coordination chemistry, is a contentious concept of some historical notoriety 37. Our findings underscore the interdependence of molecular and supramolecular effects in spin‐transition materials, and at the same time highlight the potential pitfalls inherent in the “programming” of SCO behaviour into bulk phases, both in three dimensions and, in the future, in two.…”

Section: Discussionmentioning

confidence: 99%

Parallel Crystallization of a “Static” and a Spin‐Crossover Polymorph of an Iron(II) Complex from the Same Solution

et al. 2009

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Keywords: Iron / Spin crossover / Polymorphism / N ligands / Magnetic propertiesThe ligand 2,6-bis(1H-pyrazol-1-yl)-4-(thiocyanatomethyl)-pyridine (L) has been prepared from the hydroxymethyl precursor by OH/Br exchange and subsequent thiocyanate substitution. Two polymorphs of the unsolvated iron(II) complex [Fe(L) 2 ](BF 4 ) 2 crystallize at room temperature from the same solution (MeOH), and side by side. One (yellow) is high spin between 4 and 350 K, whereas the other (red-brown) shows spin crossover, with a thermal spin-transition centred at 272 K (width ca. 50 K). Both forms have been fully charac-

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Controversy in Chemistry: What Counts as Evidence?—Two Studies in Molecular Structure

Cited by 14 publications

References 54 publications

Synthetic examination of incorrectly proposed structures of biomolecules

Synthetic examination of incorrectly proposed structures of biomolecules

The controversy about nonclassical ions: Finished too early?

Parallel Crystallization of a “Static” and a Spin‐Crossover Polymorph of an Iron(II) Complex from the Same Solution

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