Ring contraction in secondary cyclohexyl cation

See also
"Cyclopentyl, cyclohexyl, and cycloheptyl cations: computational studies of the structures, stability, 13C NMR chemical shifts, and possible rearrangement pathways."
Prakash, G.K.S., Rasul, G. Struct Chem 28, 317–326 (2017)

Confornational search: crest program (GFN2-xTB method)
P. Pracht, F. Bohle, S. Grimme, PCCP, 2020, 22, 7169-7192;
S. Grimme, JCTC, 2019, 15, 2847-2862;
P. Pracht, S. Grimme, Chem. Sci., 2021, 12, 6551-6568

TS's pathfinder: xtb --gsm (GFN2-xTB method)
See https://xtb-docs.readthedocs.io/en/latest/gsm.html

Finishing optimization, IRC and NMR chem. shifts: Priroda program (DFT/PBE/Λ1 method)
Chem. Phys. Lett. 1997, 281, 151; Russ. Chem. Bull. 2005, 54, 820
Basis Λ1 [Chem. Phys. Lett. 2005, 416, 116; Theor Chem Acc (2019) 138: 40]: H (6s,2p)→[2s,1p]; C (10s,7p,3d)→[3s,2p,1d]


Drawing of energy diagram: xyz2PES script (dot/graphviz method) + inkscape
See http://limor1.nioch.nsc.ru/quant/program/xyz2PES/


Click on ellipse to view 3D structure in popup window (run JSmol)
 image/svg+xml 13 - 12 - 11 - 10 - ~ ~ 9 - 7 - 6 - 5 - 4 - 3 - 2 - 1 - 0 - ~ ~ -1 - -12 - -13 - -12.55 kcal 3-12.55 kcal 0.38 kcal 1a0.38 kcal 3.95 kcal 1a-1b3.95 kcal 5.61 kcal 1a-1c5.61 kcal 13.02 kcal 1a-213.02 kcal 0.00 kcal 1b0.00 kcal 3.79 kcal 1b-1b3.79 kcal 1.51 kcal 21.51 kcal 3.73 kcal 2-23.73 kcal 4.95 kcal 2-34.95 kcal 3.07 kcal 1c3.07 kcal 10.08 kcal 1c-210.08 kcal 1,2-Me ~ ΔEDFT+ΔG298+ΔED3 kcal/mol
Oct 04, 2021