Self-Assembly of a Rare High Spin FeII/PdII Tetradecanuclear Cubic Cage Constructed via the Metalloligand Approach
, Richard Wuhrer 5, Shinya Hayami 3, Jack K. Clegg 6, Christopher E. Marjo 4, Leonard F. Lindoy 7 and Feng Li 1,*
Round 1
Reviewer 1 Report
The ms of Min et al. presents two coordination compounds related by their metalloligand approach.
These two compounds are interesting and probably important, however the ms should be improved as technically several issues need to be addressed.
The structure of a paper is not clear. Authors should assign numbers to precursor, ligand, Fe compound and FePd compound and all these accompany with their formulae. Already in abstract and later on.
Abstract is written as discussion and last section of the Introduction. There shell be only the most obvious results.
Results and syntheses are not clearly separated.
All methods applied are physical. Some are written as something else (other title), some (CHN,NMR) not mentioned in 2.1.
Was magsus applied to FeL and FePdL ?. How are these results connected with Fe(II) high spin ?
Author Response
Responses to reviewers:
We thanks the referees for their comments
Reviewer 1
The ms of Min et al. presents two coordination compounds related by their metalloligand approach.
These two compounds are interesting and probably important, however the ms should be improved as technically several issues need to be addressed.
The structure of a paper is not clear. Authors should assign numbers to precursor, ligand, Fe compound and FePd compound and all these accompany with their formulae. Already in abstract and later on.
Answer: As requested, each compound has now been assigned a number and each number is given along with the correspond composition where appropriate throughout the manuscript. All empirical formulas are given in table 1.
Abstract is written as discussion and last section of the Introduction. There shell be only the most obvious results.
Answer: We have followed the template for this Journal in the abstract.
Results and syntheses are not clearly separated.
Answer: We believe that we have followed the template suggested for this journal.
All methods applied are physical. Some are written as something else (other title), some (CHN,NMR) not mentioned in 2.1.
Answer: The title of 2.1 has now been changed appropriately. A description of NMR and CHN have been added.
Was magsus applied to FeL and FePdL ?. How are these results connected with Fe(II) high spin ?
Answer: We did magnetic susceptibility only for the metalloligand [FeL](BF4)2. As discussed in the manuscript, the bonding distances between Fe-N for the cage [Fe8Pd6L8](BF4)28 at 100K clearly confirmed the high spin state Fe(II). We don’t think we would learn anything new about the spin state from magnetic runs. In addition, we do not have SQUID at Western Sydney University; any further experiments would need to be performed by collaborators in Japan.
Reviewer 2 Report
This paper reports on the self-assembly of heterometallic coordination cages. The interest in large molecular cages is a well stablished field since the initial reports from Fujita in the late nineties and early noughties. Different applications have been reported on such cages, being used for drug delivery, catalysis, stabilization of unstable species, etc… As such it is important to develop effective ways for the synthesis of metallic cages. The method reported here by Li focusses in a high spin Iron species. High spin cages are not common and as such this is a fine example that can be used to take advantage of the magnetic properties of high spin iron. The cage is characterized by ESI-MS, SEM and X-ray. The high spin nature of the cage is confirmed with SQUID magnetic data. The paper is well presented, well-written and I believe that the readers of Chemistry will be interested in the methodology described.
Author Response
This paper reports on the self-assembly of heterometallic coordination cages. The interest in large molecular cages is a well stablished field since the initial reports from Fujita in the late nineties and early noughties. Different applications have been reported on such cages, being used for drug delivery, catalysis, stabilization of unstable species, etc… As such it is important to develop effective ways for the synthesis of metallic cages. The method reported here by Li focusses in a high spin Iron species. High spin cages are not common and as such this is a fine example that can be used to take advantage of the magnetic properties of high spin iron. The cage is characterized by ESI-MS, SEM and X-ray. The high spin nature of the cage is confirmed with SQUID magnetic data. The paper is well presented, well-written and I believe that the readers of Chemistry will be interested in the methodology described.
Thanks for your comments.
Reviewer 3 Report
"Self-Assembly of a Rare High Spin FeII/PdII Tetradecanuclear Cubic Cage Constructed via the Metalloligand Approach" by H. Min at al. discusses the self-assembly of a cubic Fe8-Pd6 heterobimetallic cage using the metalloligand approach.
I appreciate the paper above all by the synthesis and the structure description point of view.
1. I suggest to enclose in the conclusion section also the measured magnetic properties. Magnetic data for metalloligand can be moved in supporting materials and I suggest to show in the main text magnetic data of the cage, even when from a structural point of view, these are expected to be no far from the metalloligand one.
2. Reading the introduction emerge the importance of the ligand employed because it has been modified by the addition of some pyridil groups, it could be important in 3.4 subparagraph do a comparison about the magnetism of this system respect tha magnetism of some cages exhibiting SCO containing the unmodified ligand. "In this work, we have manipulated the ligand field of the well-studied tris(2,4-imidazolimine) coordination environment[35–37] which has been shown to result in Fe(II) SCO in most cases. We modified the ligand field by the addition of three 4-pyridyl groups (Figure 1) which resulted in HS Fe(II) centres in the metalloligand FeL(BF4)2. This metalloligand in turn gave rise to the self-assembled [Fe8Pd6L8](BF4)28 octahedral cage. Thus both HS metalloligand and heterobimetallic cage were successfully synthesised (and characterised)."
3. In the introduction are cited some synthetic method for the realization of complex structure "the symmetry-interaction approach,[9] the molecular panelling approach,[10] the subcomponent self-assembly approach[11] and the molecular-library approach.[12,13]" authors should describe with more detail the reported examples.
4. The headings of the subparagraph 3.1-3.4 should regard only characterization and no synthesis. Additionally is not necessary repeat a summury of the synthetic procedure for metalloligand and cage.
5. Check the minus upperscript for the formula of tetrafluoroborate in the whole text.
6. I suggest to add crystallographic axis in figure 2 for (a) and (b)
7. Caption of figure 4 is not well describing the image, better english editing is required.
Author Response
"Self-Assembly of a Rare High Spin FeII/PdII Tetradecanuclear Cubic Cage Constructed via the Metalloligand Approach" by H. Min at al. discusses the self-assembly of a cubic Fe8-Pd6 heterobimetallic cage using the metalloligand approach.
I appreciate the paper above all by the synthesis and the structure description point of view.
- I suggest to enclose in the conclusion section also the measured magnetic properties. Magnetic data for metalloligand can be moved in supporting materials and I suggest to show in the main text magnetic data of the cage, even when from a structural point of view, these are expected to be no far from the metalloligand one.
Answer: Thanks for your comments. We agree with this suggestion the additional data would complement the present results. Unfortunately, we do not have a SQUID at Western Sydney University, and only have quite limited access to one via collaborators in Japan. The crucial result from the present investigation is that the bonding distances between Fe-N for the cage [Fe8Pd6L8](BF4)28 at 100K clearly confirmed the high spin state for Fe(II). We propose that this is an important finding that is able to stand alone in the absence of further experiments
- Reading the introduction emerge the importance of the ligand employed because it has been modified by the addition of some pyridil groups, it could be important in 3.4 subparagraph do a comparison about the magnetism of this system respect tha magnetism of some cages exhibiting SCO containing the unmodified ligand. "In this work, we have manipulated the ligand field of the well-studied tris(2,4-imidazolimine) coordination environment[35–37] which has been shown to result in Fe(II) SCO in most cases. We modified the ligand field by the addition of three 4-pyridyl groups (Figure 1) which resulted in HS Fe(II) centres in the metalloligand FeL(BF4)2. This metalloligand in turn gave rise to the self-assembled [Fe8Pd6L8](BF4)28 octahedral cage. Thus both HS metalloligand and heterobimetallic cage were successfully synthesised (and characterised)."
Answer: The unmodified ligand may not a viable candidate for the synthesis of cages. There are some examples of the imidazoleimine chelating moiety being used in the formation of coordination cages, and some examples have been discussed in the manuscript. While a comparison between the magnetic properties of the cage presented, and other cages employing the imidazoleimine coordinating moiety could be interesting, we feel that it is outside the scope of the present work.
- In the introduction are cited some synthetic method for the realization of complex structure "the symmetry-interaction approach,[9] the molecular panelling approach,[10] the subcomponent self-assembly approach[11] and the molecular-library approach.[12,13]" authors should describe with more detail the reported examples.
Answer: Thanks, we have described the self-assembly approaches in general. We believe a more thorough description of each approach is not appropriate as part of the introduction since the reader can refer to the provided references for more information.
- The headings of the subparagraph 3.1-3.4 should regard only characterization and no synthesis. Additionally is not necessary repeat a summury of the synthetic procedure for metalloligand and cage.
Answer: Done, “synthesis and” has been removed from subheadings 3.2 and 3.3. as well as removing the first paragraph from 3.3 beginning: “To a solution….”.
- Check the minus upperscript for the formula of tetrafluoroborate in the whole text.
Answer: The minus on the BF4 is superscript. The template format font makes the superscript look like a subscript. We have changed the font of the superscript minus to Nirmala UI to make the minus look more superscript.
- I suggest to add crystallographic axis in figure 2 for (a) and (b)
Answer: the axes in figure 2 have been added
- Caption of figure 4 is not well describing the image, better english editing is require
Answer: Caption in figure has been changed to a better description.
Round 2
Reviewer 3 Report
The revised manuscript can be published in the present form.
