Diverse Hydrogen-Bonded Structural Motifs in 1,4-Diazabicyclo[2.2.2]octane N,N’-Dioxide Salts with Oxoanions
Round 1
Reviewer 1 Report
The manuscript described the preparation of four compounds derived from 1,4-diazabicyclo[2.2.2]octane N,N'-dioxide (odabco) with several acids such as nitric/perchloric/sulfuric acids. The compounds were well characterized and their crystal structures determined by single-crystal X-ray diffraction analysis. The variety of hydrogen bonding patterns was discussed from structural results. While the quality of the structures is good, the reported compounds represent a new addition to the odabco-related field and the results are suitable for publication in Molbank.
There may be a typo in line 35 in page 1:
The “five” in sentence of “…characterization of five new protonated…” should be changed to “four” since authors only reported four compounds.
Author Response
The manuscript described the preparation of four compounds derived from 1,4-diazabicyclo[2.2.2]octane N,N'-dioxide (odabco) with several acids such as nitric/perchloric/sulfuric acids. The compounds were well characterized and their crystal structures determined by single-crystal X-ray diffraction analysis. The variety of hydrogen bonding patterns was discussed from structural results. While the quality of the structures is good, the reported compounds represent a new addition to the odabco-related field and the results are suitable for publication in Molbank.
Authors are grateful to the reviewer for such a high evaluation of the work.
There may be a typo in line 35 in page 1:
The “five” in sentence of “…characterization of five new protonated…” should be changed to “four” since authors only reported four compounds.
Thank you for noting such a curious mistake. The necessary correction has been made in the revised MS.
Reviewer 2 Report
In the paper "Diverse hydrogen-bonded structural motifs in 1,4-diazabicyclo[2.2.2]octane N,N'-dioxide salts with oxoanions" Pavel A. Demakov et al. compared hydrogen bonding systems in four salt crystals with a common cation (odabco ) and various qualitatively (HNO3, HClO4, H2SO4) or quantitatively (H2SO4 and 2H2SO4) anions. Comparison of the crystal structure of the obtained salts revealed a significant difference in the structure of agglomerates bound by intermolecular hydrogen bonds. If in the case of nitrate this is a short 0D associate of a base and two counterions, then in the case of perchlorate this is already an infinite 1D chain in which anions do not participate. In the case of sulfate, the helical 1D chains formed by both the cation and the anion form around the 21 axes and are therefore chiral. In this sense Fig. 3 is not very successful, because it does not reflect this important feature. Of course, the total number of P and M helices in an achiral crystal is the same. Finally, a 3D structure is realized in bisulfate crystals.
Overall, the work appears to be of good quality and may be published in the Molbank. In addition to the incompleteness of Figure 3 noted above, the reviewer recommends correcting word five in line 35 by word four and bringing the font used in references 6 and 17 to a unified form.
Author Response
In the paper "Diverse hydrogen-bonded structural motifs in 1,4-diazabicyclo[2.2.2]octane N,N'-dioxide salts with oxoanions" Pavel A. Demakov et al. compared hydrogen bonding systems in four salt crystals with a common cation (odabco ) and various qualitatively (HNO3, HClO4, H2SO4) or quantitatively (H2SO4 and 2H2SO4) anions. Comparison of the crystal structure of the obtained salts revealed a significant difference in the structure of agglomerates bound by intermolecular hydrogen bonds. If in the case of nitrate this is a short 0D associate of a base and two counterions, then in the case of perchlorate this is already an infinite 1D chain in which anions do not participate. In the case of sulfate, the helical 1D chains formed by both the cation and the anion form around the 21 axes and are therefore chiral. In this sense Fig. 3 is not very successful, because it does not reflect this important feature. Of course, the total number of P and M helices in an achiral crystal is the same. Finally, a 3D structure is realized in bisulfate crystals.
Authors thank the reviewer for kindly high evaluation of the work. Following the issue raised by the reviewer, figure 3b has been revised.
Overall, the work appears to be of good quality and may be published in the Molbank. In addition to the incompleteness of Figure 3 noted above, the reviewer recommends correcting word five in line 35 by word four and bringing the font used in references 6 and 17 to a unified form.
The necessary corrections have been made in the revised MS.
Reviewer 3 Report
- The article is well written and explains the results with clear experimental data. The references are well organized.
- I suggest minor revisions:
- In SI I would indicate the most important frequencies in the IR spectra
- The experimental characterization of the products presented is poor. The authors say because of the instability of them. It would be advisable to add other data to complete the characterization, for example HRMS or thermogravimetric analysis etc.
Author Response
The article is well written and explains the results with clear experimental data. The references are well organized.
Authors thank the reviewer for kindly high evaluation of the work.
I suggest minor revisions:
In SI I would indicate the most important frequencies in the IR spectra
Authors thank the reviewer for this suggestion. Figs. S5-S7 have been revised accordingly.
The experimental characterization of the products presented is poor. The authors say because of the instability of them. It would be advisable to add other data to complete the characterization, for example HRMS or thermogravimetric analysis etc.
Unfortunately, we do not have a fast access to HRMS. TG analyses have not been performed due to high explosion hazard of organic nitrates and perchlorates. Following the reviewer’s suggestion, we have additionally characterized 1 – 4 by 1H-NMR spectroscopy in D2O. The corresponding spectra are added to ESI as Fig. S8. The necessary comments are added to the experimental part.
