Issue Date: September 11, 2017 Web Date: September 7, 2017
Chemists retract 15-year-old paper and publish a revised version
Keywords: research integrity, macrocycle, lanthanide complex, chemical structure
In what is being called an honest mistake, a research group has reported that the structure of the headline compound from a paper it published in 2002 is incorrect. To set the record straight, the team has retracted the paper and at the same time published a new paper reporting the actual structure.
This strategy offers chemists a palatable way to correct the literature when a pervasive error is found and the error is not the result of any ethical misconduct. Other journals, such as the Journal of the American Medical Association, have handled similar situations by retracting and replacing papers, making the original versions available in supporting information sections with errors highlighted.
The original paper published by medicinal inorganic chemist Chris Orvig and his group at the University of British Columbia reported the synthesis of a new tetraazamacrocycle ligand (Inorg. Chem. 2002, DOI: 10.1021/ic010716a). The researchers made the compound to see how replacing two methylene groups in a macrocyclic ring with phosphinate groups affected the stability of complexes formed with lanthanide ions. Such complexes are of interest as contrast agents for magnetic resonance imaging.
Orvig says all the characterization data were consistent with the ligand having a dimeric structure. But the team had a hard time growing crystals of the ligand and couldn’t confirm its structure by X-ray analysis. When graduate student David M. Weekes was recently revisiting the ligand for a new project, he was able to get a crystal structure and found the data didn’t add up, literally. Weekes discovered the molecule is half the size expected—it is monomeric, not dimeric—and forms a 2:1 complex with lanthanides instead of a 1:1 complex as originally thought.
An incorrect structure might normally be handled by issuing a correction statement appended to the paper pointing out the error. But in this case, Orvig says, the incorrect assumption of the ligand structure nullified the conclusions. Orvig and the journal’s editors agreed the best solution would be to retract the paper (Inorg. Chem. 2017, DOI: 10.1021/acs.inorgchem.7b01932). But they also agreed that Orvig’s group could publish a new paper along with the retraction reporting the correct structure (Inorg. Chem. 2017, DOI: 10.1021/acs.inorgchem.7b01117). The event was first reported by Retraction Watch, a blog that aims to increase the visibility of the retraction process for scientific papers.
Orvig says it was important and the right thing to do to correct the literature, even if a little embarrassing, given that some researchers might have already tried to make the ligand and failed, and others might continue to do so. “This is the way science is supposed to work—correcting itself,” Orvig says.
Retracting a paper oftentimes is associated with misconduct—fabrication, plagiarism, or rigged peer review. Some researchers have suggested that papers like Orvig’s should be given a status different than retraction: For example, “withdrawal” could be used for an honest mistake, and “retraction” could be reserved for misconduct.
Inorganic Chemistry editor-in-chief William B. Tolman of the University of Minnesota applauds Orvig for coming forward to self-correct the mistake, when others might not have done so. “This is precisely why the retraction mechanism exists—to correct the published record,” Tolman says. “Orvig realized the error, did a bunch of work to reexamine it, and then pushed to have it corrected in the literature despite it being years later.” Tolman adds that he would hope researchers view this case as one of many data points in the larger story of how science corrects itself.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society
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Chris Orvig is a very honest in his reporting. That is how honest people report their new findings if they see that it differs from what they have reported before. I do have some examples that i will be happy to share with C&EN-News.
Prof. Hamada
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The ligand in question can be formed in a "Mannich-type" reaction between
formaldehyde, a secondary amine, and hypophosphorous acid (H3PO2).
Such reactions are reversible in the presence of water and Lewis-acid
catalysts or H+.
It is thus possible that there is an equilibrium between the monomer and the
dimer, and that the monomer crystallized more easily out of the equilibrium
mixture. But this is not sufficient evidence for affirming that all of its complexes
must contain it in the monomeric form, too. I dare suppose that adding Ni(2+) to
the monomeric ligand will push it into the dimeric form, because it prefers nitrogen
ligands over phosphinate and carboxylate oxygen. For other metal ions, such
as the lanthanide ions, there might be equilibria between both forms, as they like more carboxylate and phosphinate oxygen ligands than nitrogen ligands.
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If it was a static/dynamic mixture, the NMR/VT-NMR would have shown some evidence. Unlike crystallography, which uses micrograms sample, NMR, especially 31P NMR uses several milligrams. Normally it will represent the sample better. About 10 mg seems to have been used in the original NMR study. 1H and 31P NMR data seems normal.
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The published comments/letters from Richard and Robert Buntrock,although somewhat thoughtful,contain terribly awful syntax effectively reducing their impact. In fact, it is an embarrassment to any educated individual. Maybe you should contact them before publication with suggested edifications. After all, this is supposed to be a professional trade journal.
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