Ag(I) Complexes of Imine Derivatives of Unexpected 2-Thiophenemethylamine Homo-Coupling and Bis-(E)-N-(furan-2-ylmethyl)-1-(quinolin-2-yl)methanimine
Round 1
Reviewer 1 Report
The manuscript by Omondi and coworkers describes the synthesis of two Ag(I) complexes of heterocyclic imines and the full characterization of both complexes. These compounds will be of interest to Molbank readers and I recommend acceptance of this manuscript with minor revision, as follows:
- Abstract: The authors mention "an unexpected chemoselective hydrolytic cleavage of one mole of the (CH=N) imine ligands". The possibility of an imine metathesis process should be considered.
- In the description of compounds, protons are designed as Hb, Hc, Hg, etc. These protons should be identified in the structure of the compounds.
- Synthesis of L2: "The oil obtained was recrystallized from ethanol and dried over anhydrous magnesium sulfate." This sentence is not very clear. How was a solid compound dried over MgSO4?
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The structure of the 3-coordinate pyridinyl imine Ag(I) complexes (1) is rather unexpected, as mentioned by the authors. Can they cite literature precedent for such a structure? What is the distance between S1 and Ag1 in the X-Ray structure?
Author Response
Dear Reviewer,
Thank you for your comments, corrections, and suggestions. We have responded to all the comments and read the manuscript to clean it up further. Kindly find attached the detailed rebuttal of the comments.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The authors describe several imines, one of which is known, and then convert these imines to silver complexes. The compounds are adequately characterised.
The formation of the imines is trivial, and would not warrant publication, however, the silver complexes are novel. These are characterised by X-Ray diffraction as well as NMR establishing structure.
The most interesting part of the article was the silver promoted oxidative homocoupling of thiophenylmethylamine to give the bis thiophene which was unexpected.
The yields in the experimental must be corrected. From the experimental for complex 2, a 2:1 complex should form, yet the total mass of the product is greater than the theoretical. A combined mass of ligand and silver perchlorate of 370 mg affords 630 mg of product without explanation and there is no solvent in the X-Ray structures. Similar issues arise in the description of Complex 1.
In the synthesis of L2, the experimental should be corrected. The product is not described properly with regards to appearance. It is unclear if the authors collected the crystalline product and then dried it? If so the text should indicate the use of a dessicator. The experimental reads that the oil was dried with MgSO4 in a solvent free environment, then recrystallised. This doesnt make sense to me, considering that only 180 mg of materials was obtained. How was the MgSO4 removed from the oil?
The experimental is also not precise. It gives inexact masses of starting materials (ca 0.1 mL) then calculates yields to 2 sig figures. Masses of starting materials need to be given, even though the synthesis is trivial. These should also be given to a sufficient degree of accuracy such that the yield can be calculated.
A description of thiophene and furan use is not necessary in this article and this discussion is superfluous to the chemistry described - starting line 43.
Author Response
Dear Reviewer,
Thank you for your comments, corrections, and suggestions. We have responded to all the comments and read the manuscript to clean it up further. Kindly find attached the detailed rebuttal of the comments.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The article has been improved relative to the first instance.
A few minor issues that could still be fixed.
Remove the ca. from the experimental. Ca. is an abbreviation for about, not calculated which is what the authors seem to be using it for.... The amount that was used in the experiments must be exact and must have been recorded, so I am putting this down to an error in usage.
Lien 45. Remove However,
Line 76 Capitalise the first letter of the sentence.
Author Response
Dear Reviewer,
Thank you for your corrections, suggestions, and prompt response. We have attended to the comments as follows:
Comment 1:
Remove the ca. from the experimental. Ca. is an abbreviation for about, not calculated which is what the authors seem to be using it for.... The amount that was used in the experiments must be exact and must have been recorded, so I am putting this down to an error in usage.
Response 1:
Thank you for the correction. Ca. has now been removed for the experimental section since the exact amount used was recorded.
Comment 2:
Lien 45. Remove However,
Response 2:
Thank you for the correction. “However” has been removed from line 45. Line 45 is now as follows:
“Their coordination to transition metals has been reported to enhance their biological activities.”
Comment 3:
Line 76 Capitalise the first letter of the sentence.
Response 3:
Thank you for the correction. Line 76 is now as follows:
“Synthesis of L1: 4-pyridinecarboxaldehyde (1 mmol, 0.11 g, 0.09 mL) in anhydrous”
Sincerely,
Ms. A.A Adeleke
