Structures of Hydrated Metal Ions in Solid State and Aqueous Solution

Round 1

Reviewer 1 Report

Reviews attached. 

Comments for author File: Comments.pdf

Author Response

General comments:

1. There is no evidence for equilibria between different coordination number and figures of hydrated and solvated metal ions in solution except in a limited number of cases. When such equilibria may exist, comments have been made in the text. Therefore, I find it incorrect to make a statement of the kind reviewer 1 proposes. The scattering events of X-rays and neutrons in material is the order of 10^-15 seconds, which is much faster than e.g. water exchange equilibria. This results in a significantly wider bond distance distribution and a different M-O bond distance compared to when a single coordination geometry is dominating as there is a very strict correlation between coordination figure and number and M-O bond distance for a specified ligand as water.
2. The physical parameters in Eqs. (1) and (2) are now denoted.
3. I do not like the idea to include mean M-O bond distances in Table 1 as the table then will include two messages and will become messy. I have therefore as an alternative prepared a Table 2 summarizing the mean M-O bond distances for hydrated metal ions in solid state and aqueous solution for an easier comparison.

Specific comments

1. The reference Phys Chem. B 2015, 119, 2003-2009 is now included.
2. I have decided to not include data at extreme conditions. I have unfortunately missed the reference Phys Chem. B 2007, 111, 13570-13577 was not included in the reviews I did refer to, ref. 20 and 21. The citation is now included.

3-7. The typos are corrected.

Reviewer 2 Report

The review on "Structures of hydrated metal ions in solid state and aqueous solution" gives a comprehensive overview on the solvation structures of metal ions in solid state and liquid state. I recommend it to be published as is.

However, I'd like to mention the following points:

The instrumental section is written very brief and might benefit from some more details. Anyways, appropiate citations are given for further reading.

It might be more instructural to give a few examples of original data or structures to illustrate the described structures.

Typos in references:
Ref. 6: ...ammo-.nium...
Ref. 49: ca²⁺ --> Ca²⁺

Author Response

Further citations are given describing the EXAFS and LAXS methods, references 1-3 and 4-5, respectively.

The typos are corrected.

Reviewer 3 Report

This manuscript extensively summarizes the hydrated metal ions observed in solid state and aqueous solutions. Methods used for identifying structures are well-defined. Ion configurations and coordination numbers associated are explicitly explained. This review prompts a compressive picture of the family of coordinated metal ions. I suggest the manuscript be published after minor revision.

1. References for Eq. (1) and (2) are suggested for clarification to the audience.

2. Format:

Line 52: font for the first sentence needs to be adjusted.

Line 510: No spacing is needed before ‘3.3.5.1 Titanium (III)’.

Author Response

I can do a compressive picture of the different structural configurations hydrated metal ions may have if the editor require it. However, I do not find it necessary as this knowledge is of general character and very easy to find in general chemical literature and on internet.

The physical parameters in Eqs. (1) and (2) are now denoted, and further citations are given describing the EXAFS and LAXS methods, references 1-3 and 4-5, respectively.

The typos are corrected.