ESR and Mössbauer Spectroscopy of Iron(III) Spin Crossover Complexes Based on Pentadentate Schiff Base Ligands with Pseudohalide Coligands

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Could you please give me a chance to review a apparently valuable, attractive and important Fe（III）SCO materials using ESR , Mössbauer Spectroscopy and the ab initio calculations  in order to obtain apparently valuable data associated with apparently interesting　and sophisticated SCO behaviors?

  This paper reports attractive research area of Spin Crossover Behaviors associated with very deeply and fully precise studies mainly using ESR , Mössbauer Spectroscopy and the ab initio calculations. I also feel that there might be a deeply strong emphasis on magnetochemistry studies which involve a range of spectroscopic and structural techniques, in particular Mossbauer spectroscopy, for very valuable and important Fe(III)SCO compounds associated with molecular magnetism

I feel that  this  apparently great and valuable original paper is associated with a　particularly　successful　and　potentially　developing　research　kingdom　for　spin crossover　 iron(III)　 complexes with valuable and sophisticated functional magnetochemistry properties .The SCO behaviors in this paper might be novel phenomena of SCO materials, and the results presented here expand further the known magnetochemistry and,  magnetic and related properties accessible to developing the structural and magnetic properties associated with potential application smart materials as sensors and memories so on.

I feel that the authors might be expert in these SCO fields and the Mössbauer spectroscopic characterization reported here appears to be well carried out.  I feel that this paper demonstrates conventional Fe-57 Mossbauer spectroscopy is also very powerful and helpful tool for SCO materials. The author may wish to consider the following points when putting together a very suitable version of the very important and attractive manuscript.

1)Line widths in Mössbauer parameters are very important and valuable.  As to Mossbauer Figures, the specialists for Mossbauer spectroscopy must consider the asymmetry.

2) The time window for Mossbauer spectroscopy is different from that of ESR. Would the authors please explain in more detail the time windows of the measurements for SCO Iron(III) materials.  

 

3) A very interesting SCO behavior in this paper should be explained using many aspects of some models for SCO mechanisms.
4) Would you please explain more in detail the values of the high spin states in the Figures?

5) I feel that references should be more updated. I feel that references might be unfair since many research groups have been developing various interesting SCO behaviors using various aspects of coordination chemistry such as using Mossbauer spectroscopy associated with evolution on structural chemistry and magnetochemistry. I feel Nuclear Forward Scattering: NFS and Nuclear Inelastic Scattering :NIS using Synchrotron might be useful for SCO behaviors.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the manuscript entitled "ESR and Mössbauer Spectroscopy on Pentadentate Iron(III) Spin Crossover Complexes with Pseudohalide Coligands" Lucka et al. present the Mössbauer and ESR spectra of two mononuclear Fe(III) complexes that were previously shown to exhibit spin crossover behaviour. Although the manuscript "only" confirms the previously reported SCO effects, the study is performed well and the conclusions drawn from the in-depth analysis of the new spectral data sound and thus merits publication after some minor points have been addressed.

• One issue concerns the title which in its current form is wrong. The complexes are not pentadentate. The six-coordinate Fe(III) centres are coordinated by a pentadentate Schiff base ligand though.
• The English although generally good and perfectly understandable would benefit from another spell/grammar check, e. g. "solid-state cooperativity" (line 35), "show typical" (line 50), "is temperature dependent" (line 59), "by strongly interacting" (line 80), etc.
• Please include the molecular structure of compound 2 in Figure 1 and indicate the probability levels the anisotropy ellipsoids were drawn at.
• Please provide some references to the explanation of decreasing quadrupole splitting at higher temperatures (sentence starting in line 54 and ending in line 56).
• The simulations of the ESR spectra should be included in Figure 3. Furthermore, the quality of Figure 3 is rather poor (particularly the 77K spectra) and should be remade in higher quality. 
• Why is the experimental information of an additional complex [Fe(⁵Cl-L)(Cl)] reported in the experimental section? The elemental analyses of compounds 1 and 2 were simply copied from reference 15 where the compounds were initially reported and characterised. Were the measurements reported here performed on the same sample batches (from at least 12 years ago)? Or were the compounds reproduced as suggested by the sentence in line 121 and 122? In the latter case the elemental analyses of the sample batches that were used for the reported measurements should be added in order to provide a proof of purity.

Author Response

Please see the attachment

Author Response File: Author Response.pdf