Exploring the Potential Energy Surface of Medium-Sized Aromatic Polycyclic Systems with Embedded Planar Tetracoordinate Carbons: A Guided Approach
, Luis Leyva-Parra 1,2, Osvaldo Yañez 3, Andrew L. Cooksy 4, Venkatesan S. Thimmakondu 4,* and William Tiznado 1,*Round 1
Reviewer 1 Report
The authors have presented an interesting study designing a compound featuring planar tetracoordinate motifs. The design principle was proven to work on other compounds as was shown previously and they employed coronene as a template structure. This is a novel methodology to explore a potential energy surface using PAHs as starting materials. The manuscript is recommendation for publication after the following minor suggestions are taken into consideration.
1. The authors have emphasized a defining feature of the studied species Si8C22, i.e. Si-ptC-Si three-center two-electron sigma bonds. It is a more general phenomenon for hypercoordinate species, it could be pointed out in the manuscript that forcing C/Si atoms to adopt hypercoordinate bonding can alter the bonding qualitatively, up to the ultimate case when the atoms could be bonded together only through delocalized sigma bonds. For example, the authors could mention these papers (J. Am. Chem. Soc. 2015, 137, 2757–2762; Phys. Chem. Chem. Phys. 2015, 17, 26043–26048), where it was found that the stability of the hexacoordinate Si motifs comes form the multicenter sigma bonds only. Forcing C/Si atoms from planar coordinate to planar hexacoordinate configurations forces these atoms to form multicenter sigma bonds exclusively due to the electron deficiency and specific quantum confinement.
2. 5c-2e pi bonds shown in Figure 2 have an overlap, which is prohibited by AdNDP. While the sigma bonding makes sense, the partitioning of the pi density seems to be a little biased. Overcounting of the pi density should be revised.
3. The appearance of the 6c-2e pi bond seems to be artificial. Otherwise, the pi density should be found as more localized fragments. So, this is suggested for revision.
Author Response
Please find our response in the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The paper written by D. Instraonaz et al. discusses the use of potential energy surface analysis to design systems involving planar tetravalent carbon atoms. The authors present their findings clearly and provide a precise description of the subject. The methodology used is appropriate but needs some refinement, as mentioned by the authors.
In my opinion, the manuscript is ready for publication as it is. However, I suggest that the authors explain why they chose the DFT functional (PBE0 with D3 dispersion correction) instead of alternative methods like omegaB97XD. This explanation would benefit a wide range of readers.
Author Response
Please find our response in the attached file.
Author Response File: Author Response.pdf
