torquoselectivity of the ring-opening reaction of 3,3

doi.org/10.26434/chemrxiv.9178121.v1

Torquoselectivity of the Ring-Opening Reaction of 3,3-DihalosubstitutedCyclobutenes: Lone Pair Repulsion and Cyclic Orbital InteractionYuji Naruse, Atsushi Takamori

Submitted date: 31/07/2019 • Posted date: 31/07/2019Licence: CC BY-NC-ND 4.0Citation information: Naruse, Yuji; Takamori, Atsushi (2019): Torquoselectivity of the Ring-Opening Reactionof 3,3-Dihalosubstituted Cyclobutenes: Lone Pair Repulsion and Cyclic Orbital Interaction. ChemRxiv.Preprint.

Three major factors determine torquoselectivity, which is the diastereoselectivity in electrocyclic ring-openingreactions to produce E/Z-double bond(s). One is the interaction between the decomposing sCC bond andlow-lying vacant orbital(s), such as a p*- or s*-orbital on the substituent, which promotes the reaction, resultingin inward rotation of the substituent. Second, for a substituent with a lone pair(s), repulsive interactionbetween the decomposing s-bond and the lone pair(s) hinders inward rotation, so that the products of outwardrotation should be preferred. Finally, a more strongly donating s-electron-donating group (sEDG) rotatesinwardly due to stabilization by phase-continuous cyclic orbital interaction. We compared the latter twointeractions, repulsion between the lone pairs on the substituent and stabilization from phase-continuouscyclic orbital interaction, to determine which has a greater effect on the diastereoselectivity. We considered aseries of model reactions with halogen substituents, and concluded that the diastereoselectivity is mainlycontrolled by cyclic orbital interaction.

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1

Torquoselectivity of the Ring-Opening Reaction of

3,3-Dihalosubstituted Cyclobutenes: Lone Pair

Repulsion and Cyclic Orbital Interaction

Yuji Naruse1,2* and Atsushi Takamori1

1Department of Materials Chemistry and Processing, Graduate School of Gifu University, 1-1,

Yanagido, Gifu, 501-1193 JAPAN , 2Department of Chemistry and Biomolecular Science, Gifu

University, 1-1, Yanagido, Gifu, 501-1193 JAPAN

KEYWORDS: Torquoselectivity, Electrocyclic Ring-Opening Reaction, Geminal Bond

Participation, Bond Model Analysis.

ABSTRACT. Three major factors determine torquoselectivity, which is the diastereoselectivity

in electrocyclic ring-opening reactions to produce E/Z-double bond(s). One is the interaction

between the decomposing CC bond and low-lying vacant orbital(s), such as a *- or *-orbital

on the substituent, which promotes the reaction, resulting in inward rotation of the substituent.

Second, for a substituent with a lone pair(s), repulsive interaction between the decomposing -

bond and the lone pair(s) hinders inward rotation, so that the products of outward rotation should

be preferred. Finally, a more strongly donating -electron-donating group (EDG) rotates

2

inwardly due to stabilization by phase-continuous cyclic orbital interaction. We compared the

latter two interactions, repulsion between the lone pairs on the substituent and stabilization from

phase-continuous cyclic orbital interaction, to determine which has a greater effect on the

diastereoselectivity. We considered a series of model reactions with halogen substituents, and

concluded that the diastereoselectivity is mainly controlled by cyclic orbital interaction.

1. Introduction

Torquoselectivity is the diastereoselectivity in electrocyclic ring-opening reactions that produces

E-/Z-isomers of the double bond.1-4 Many reports have discussed this diastereoselectivity,

especially with regard to the electrocyclic ring-opening reaction of 3-substituted cyclobutenes.

However, the diastereoselectivity often does not seem to be guided by steric considerations, so

that electronic effects need to be considered. Three major interactions of the electronic effect

have been proposed to explain this torquoselectivity (Figure 1).

Figure 1. Torquoselectivity of 3-substituted cyclobutenes and its proposed electronic effects.

3

One is the interaction between the decomposing CC bond and a low-lying vacant orbital, such

as a *- or *-orbital on the substituent, which promotes the reaction (Figure 1a).3-6 Cyclobutene

with an alkoxycarbonyl group at the 3-position was reported to show torquoselectivity with

inward rotation of the alkoxycarbonyl group. This would be a donor-acceptor interaction, and

hence an attractive interaction, and the TS should be considerably stabilized, resulting in inward

rotation of the substituent. On the other hand, interaction between the decomposing CC bond and

the lone pair(s) on the substituent is a type of donor-donor interaction, which leads to repulsive

destabilization. Substituent(s) with lone pairs should prefer outward rotation (Figure 1b).

In contrast, Inagaki proposed that phase-continuous cyclic orbital interaction8 that includes

geminal bond participation controls the diastereoselectivity (Figures 1c and 1d).7b The cyclic

orbital interactions among *C=C, decomposing CC and C-D of the -donating group (EDG) D

(Figure 1c) and among C=C, decomposing *CC and C-D (Figure 1d) satisfy the phase continuity

requirements, so that electron delocalization among them is enhanced to produce considerable

stabilization at TSs.

We wondered which of these three effects controlled the diastereoselectivity most effectively.

As a first step, we compared the effects of the latter two, i.e., the repulsive interaction between

the decomposing CC bond and the lone pair(s) on the substituent(s) and the cyclic orbital

interaction including geminal bond participation.

2. Expected torquoselectivity

To compare these effects, we should choose a system that is free from bond interaction on the

substituent(s). Thus, we chose 3,3-dihalocyclobutenes 1 as models. Halogens are monovalent, so

that there no other bonds on the substituent(s) and no effects from the * or *-orbital. The

4

atomic radii of halogens are in the order F < Cl < Br and the bond lengths of carbon-halogen

bonds are in the order C-F < C-Cl < C-Br. If repulsion with the decomposing CC bond is the

main contributor to diastereoselectivity, the preference for inward rotation should be in the order

F > Cl > Br, considering the atomic radii. In contrast, if a longer bond length reduces repulsion,

the order of preference should be reversed to F < Cl < Br.

Figure 2. 3,3-Dihalocyclobutenes considered.

From the perspective of cyclic orbital interaction7b,8, the energy level of C-X is well correlated

with electronegativity, so that the donating character is in the order C-F < C-Cl < C-Br, since

fluorine is the most electronegative (4.0), followed by chlorine (2.8) and bromine (2.7). We

previously confirmed this order by evaluating the energy levels of C-X bond orbitals: C-F (-

1.068 a.u.) < C-Cl (-0.882 a.u.) <C-Br (-0.834 a.u.).7b-d,9 Since the more strongly donating

character of the geminal C-X bond enhances the cyclic orbital interaction among *C=C,

decomposing CC and C-D and among C=C, decomposing *CC and C-D, we can expect that the

preference for inward rotation should be in the order F < Cl < Br.

3. Theoretical calculations

First, we performed theoretical calculations at the M06-2X/6-311++G** level (Figure 3).10

The results are summarized in Table 1.

5

Figure 3. Optimized TS structures (M06-2X/6-311++G**).

Table 1. Torquoselectivity of 3,3-dihalocyclobutenes (kcal/mol, M06-2X/6-311++G**)

substrate E‡(X1 inward) E‡(X2 inward) E‡

1a

(X1 = F; X2 = Cl) TS1ain 42.4 TS1aout 41.6 0.74

1b

(X1 = F; X2 = Br) TS1bin 42.4 TS1bout 41.2 1.2

1c

(X1 = Cl; X2 = Br) TS1cin 41.5 TS1cout 41.0 0.43

1d

(X1 = X2 = F) TS1d 42.7

] 1.3

] 1.6 1e

(X1 = X2 =Cl) TS1e 41.4

] 0.3 1f

(X1 = X2 = Br) TS1f 41.1

6

Apparently, the preference for inward rotation is in the order F < Cl < Br. The activation

energies are in the order TS1d (difluoro, 42.7 kcal/mol) > TS1e (dichloro, 41.4 kcal/mol) >

TS1f (41.1 kcal/mol, dibromo), and there is a preference for inward rotation of a chloro group

in TS1a and a bromo group in TS1b and TS1c. There is some regularity in these values. The

activation energies E‡ for fluoro-inward rotation of TS1ain (42.4 kcal/mol) and TS1bin (42.4

kcal/mol) are almost the same as that of difluoro TS1d (42.7 kcal/mol), the activation energies

E‡ for chloro-inward rotation of TS1aout (41.6 kcal/mol) and TS1cin (41.5 kcal/mol) are

almost the same as that of dichloro 1e (41.4 kcal/mol), and finally, the activation energies E‡ for

bromo-inward rotation of TS1bout (41.2 kcal/mol) and TS1cout (41.0 kcal/mol) are almost the

same as that of dibromo TS1e (41.1 kcal/mol). These results clearly indicate that the activation

energy heavily depends on the substituent that rotates inward.

Figure 3. Relationship among the optimized activation energies.

Furthermore, the activation energy decreases with the outward-rotating substituent in the

order of F > Cl > Br, e.g., 1d (outward F: 42.7 kcal/mol) > 1a (outward Cl: 42.4 kcal/mol) ~ 1b

(outward Br: 42.4 kcal/mol) in the inward-F series, and 1a (outward F: 41.6 kcal/mol) > 1e

(outward Cl:41.4 kcal/mol) > 1c (outward Br: 41.0 kcal/mol) in the inward-Cl series. For the

inward Br series, there are no apparent differences of ca. 0.1 kcal/mol.

We can expect that these relationships can be attributed to the inductive effect. The stronger

-electron-withdrawing group attracts electrons on other atoms in the neighborhood, so that the

-bond energies of the other substituent bonds should be lowered. This inductive effect also

7

affects the charge on the other substituents to reduce steric repulsion while the bond lengths are

almost the same.

Thus, we can conclude that the obtained values are consistent with our expectation. Repulsion

should be reduced with longer bond lengths, and only the -bond of the substituent C-X bond

with inward rotation is involved in the cyclic orbital interaction. Thus, we can expect that one of

these two effects should mainly control the torquoselectivity.

4. Bond model analysis

To determine which effect should contribute more to the torquoselectivity, we performed a

bond model analysis11 to evaluate the bond interactions. We used the interbond energy IBE12 for

this evaluation. Due to the difficulty of separating the lone pairs of the valence electrons and the

core orbitals, we evaluated the sum IBE(CC-nX) of the repulsive interactions between

decomposing CC and the lone pairs on the halogen atom that rotates inward. We summarize our

analysis in Table 2.

Table 2. Charge and bond interactions (IBE in a.u., RHF/6-31G(d)//M06-2X/6-311++G**).

Lone pair repulsion

Cyclic orbital interaction

Among

CC-*C=C-C-D- orbitals

Among

C=C-*CC-C-D- orbitals

Mulliken

charge on

Xa

IBE(C

C-nX)/a.u.

IBE(CC-

*C=C)/a.u.

IBE(C-D-

*C=C)/a.u.

IBE(C=C-

*CC)/a.u.

IBE(C-D-

*CC)/a.u.

1a F-inward 0.0457

(-0.3370) 0.7814 -2.2363 -0.0356 -1.0408 0.0798

1a Cl-inward 0.1492

(0.0126) 0.8466 -2.2637 -0.0601 -1.1634 0.3288

1b F-inward 0.0366

(-0.3898) 0.9466 -2.6783 -0.0406 -1.2335 0.0981

1b Br-inward -0.0232 0.9495 -2.7379 -0.1082 -1.4206 0.4624

8

(-0.1045)

1c Cl-inward 0.1138

(0.0574) 1.1782 -2.6154 -0.0996 -1.5448 0.3961

1c Br-inward -0.0571

(-0.0568) 1.1044 -2.6363 -0.1118 -1.6146 0.3358

1d difluoro -0.0236

(-0.3360) 0.6758 -2.1999 -0.0263 -0.8872 0.0743

1e dichloro 0.1042

(0.0439) 1.0088 -2.2158 -0.0826 -1.1340 0.3229

1e dibromo -0.0343

(-0.0517) 1.2536 -3.0452 -0.1619 -1.8195 0.5669

aM06-2X/6-311++G**; at the level of RHF/6-31G(d)//M06-2X/6-311++G** in parentheses.

First, the evaluated steric repulsion IBE(CC-nX) is in the order F < Cl < Br, which is

opposite the order we expected. From a charge perspective, there is no correlation with the

changes in the activation energies. The steric repulsion should mostly depend on the atomic radii

of the halogens. The only exception is the case of 1c, where less steric repulsion is calculated for

the inward rotation of Br. We suppose that the longer bond length of C-Br (1.957 Å, M06-2X/6-

311++G**) compared to that of C-Cl (1.785 Å) would be the main contributor in this case.

Considering these results, we conclude that steric repulsion does not control the torquoselectivity.

For the cyclic orbital interaction, stabilization due to the bond interactions between CC and

*C=C and between C-D and *C=C in the cyclic orbital interaction among CC-*C=C-C-D-

orbitals, and those between C=C and *CC and between C-D-*CC in the cyclic orbital

interaction among C=C-*CC-C-D- orbitals are all enhanced in the order F < Cl < Br. For inward

rotation of the same atom, repulsive interaction increased in the order F < Cl < Br. In contrast,

the stabilization from the cyclic orbital interactions also increased. They should cancel each other

so that the activation energies remained almost the same regardless of the substituent rotating

outward. For example, in fluoro-inward rotation, repulsion between the decomposing CC and

lone pairs on the halogen IBE(CC-nX) increases according to the outward-rotating substituent

9

in the order F (1d, fluoro-outward: 0.6758 a.u.) < Cl (1a, Cl-outward: 0.7814 a.u.) < Br (1b, Br-

outward: 0.9466 a.u.). On the other hand, stabilization from CC-*C=C in the cyclic orbital

interaction is in the order F (1d, -2.1999 a.u.) < Cl (1a, -2.2363 a.u.) < Br (1b, -2.6783 a.u.).

Note that the geminal interaction between C-D-*CC shows an antibonding character of IBE

values. Inagaki explained this phenomenon in terms of the antibonding nature of geminal

delocalization.13 The geminal bond interaction was erroneously considered to mean that there

was no interaction between the two geminal bonds. However, although the two hybrid orbitals on

the center atom are orthogonal, the geminal bonds still interact mostly via the hybrid orbital at

the terminal positions (Figure 4). The phase between the two geminal bonds is determined by the

two hybrid orbitals on the center atom. Thus, the overlaps between the other three hybrids should

often be out-of-phase combinations for the obtuse bond angle, which results in the antibonding

nature. This characteristic of geminal delocalization leads to the positive values for IBEs. Thus,

we can conclude that a more electron-donating character of EDG prefers inward rotation by

enhancing the cyclic orbital interaction, i.e., the order of electronegativity F > Cl > Br should

result in the donating character of a C-X bond to be in the order C-F < C-Cl < C-Br, so that the

preference for inward rotation is in the order F < Cl < Br due to the stabilization from the cyclic

orbital interaction at the TS. These results are in good agreement with our expectations.

Figure 4. Phase relationship and overlaps in geminal delocalization

Conclusion

10

We evaluated the electronic effects that affect torquoselectivity in the electrocyclic ring-

opening reaction of 3,3-dihalocyclobutenes. According to theoretical calculations, the change in

activation energies is in the order F > Cl > Br. From the perspective of repulsion between the

decomposing CC and the lone pair(s) on the halogens, the order was assumed to result from

longer bond lengths. On the other hand, from the perspective of cyclic orbital interaction, the

order was believed to be due to phase-continuous cyclic orbital interactions, where the electron-

donating ability of the C-X bond is essential. Electronegativity is in the order F > Cl > Br, and

thus, the -bond orbital energy is in the orderC-F < C-Cl < C-Br. The cyclic orbital interaction

is enhanced in the order F < Cl < Br. According to our bond model analysis, the change in cyclic

orbital interaction is consistent with our expectation, while repulsive interaction between the

decomposing CC and the lone pair(s) on the halogens does not follow the change in the

activation energies. Thus, we conclude that the cyclic orbital interaction controls

torquoselectivity in the electrocyclic ring-opening reaction of 3,3-dihalocyclobutenes.

ASSOCIATED CONTENT

Supporting Information. Summary of the theoretical calculations. This material is available

free of charge via the Internet.

Author Contributions

Both authors contributed to writing the manuscript and approved the final version of the

manuscript.

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Supporting Information.

12

11. (a) Bond Model Analysis 1.1 Inagaki, S.; Ikeda, H.; Ohwada, T.; Takahama, T. 1996-2013.

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where Pij, Hij, and Fij are the elements of the density, Fock and core Hamiltonian matrices of the

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Insert Table of Contents Graphic and Synopsis Here

13

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M06-2X/6-311++G**

1a F-Cl reactant

Frequencies -- 165.2802 281.2907 359.8175

Sum of electronic and zero-point Energies= -714.712300

Sum of electronic and thermal Energies= -714.706882

Sum of electronic and thermal Enthalpies= -714.705938

Sum of electronic and thermal Free Energies= -714.741704

1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.333858

3 6 0 1.498834 0.000000 -0.065359

4 6 0 1.513169 -0.011645 1.483776

5 1 0 -0.750279 0.013383 -0.778079

6 1 0 -0.791779 0.017608 2.071658

7 9 0 2.066264 -1.096703 -0.640447

8 17 0 2.237218 1.438952 -0.830967

9 1 0 1.962980 0.867000 1.945668

10 1 0 1.943919 -0.925880 1.894438

TS1ain F-Cl-ts F-inward

Frequencies -- -673.6097 190.1844 249.6412





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.384206

3 6 0 1.376690 0.000000 -0.287797

4 6 0 1.221007 0.578411 1.777391

5 1 0 -0.799636 0.097911 -0.723700

6 1 0 -0.733195 -0.444502 2.050433

7 9 0 2.167777 -1.061690 -0.041259

8 17 0 1.990886 0.820251 -1.704952

9 1 0 1.484848 1.550774 1.386172

10 1 0 1.743803 0.282108 2.684956

.delta.E++ = 0.067491 a.u. = 42.4 kcal/mol

.delta.G++ = 0.067393 a.u. = 42.3 kcal/mol

14

.delta..delta.E++ = 0.001173 a.u. = 0.74 kcal/mol

.delta..delta.G++ = 0.001105 a.u. = 0.69 kcal/mol

IRC final strucures

stru. 1

1 6 0 -0.983558 0.414002 0.321754

2 6 0 -1.375566 0.131515 1.704705

3 6 0 0.129625 0.012088 -0.280396

4 6 0 -0.654817 -0.462413 2.658955

5 1 0 -1.660857 0.997818 -0.287271

6 1 0 -2.379485 0.460910 1.953801

7 9 0 1.057699 -0.721609 0.320084

8 17 0 0.552529 0.358154 -1.910693

9 1 0 0.355295 -0.815280 2.501780

10 1 0 -1.081773 -0.600912 3.644002

stru. 2

1 6 0 -1.406354 -0.462921 0.229273

2 6 0 -1.449988 0.167620 1.403871

3 6 0 0.072893 -0.252027 0.096322

4 6 0 0.038035 0.474464 1.464592

5 1 0 -2.122061 -0.942750 -0.423151

6 1 0 -2.257205 0.400866 2.086047

7 9 0 0.832221 -1.382919 0.080858

8 17 0 0.589654 0.749443 -1.293704

9 1 0 0.319602 1.527112 1.433497

10 1 0 0.601297 -0.052060 2.236347

TS1aout Cl-F-ts Cl-inward

Frequencies -- -608.2079 213.0030 244.4735





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.381666

3 6 0 1.368927 0.000000 -0.321843

4 6 0 1.234819 0.542313 1.779298

5 1 0 -0.802243 0.088057 -0.723274

6 1 0 -0.740624 -0.434921 2.044524

7 17 0 2.435739 -1.387228 -0.145812

8 9 0 1.765337 0.670406 -1.413049

9 1 0 1.528559 1.509146 1.396549

10 1 0 1.751125 0.223507 2.683434



IRC final structures

stru. 1

1 6 0 -1.496455 -0.037433 -0.009824

2 6 0 -1.542503 0.509225 1.204500

3 6 0 -0.028485 0.238433 -0.150544

4 6 0 -0.072133 0.893265 1.252605

5 1 0 -2.198849 -0.527153 -0.669971

6 1 0 -2.338023 0.635678 1.928363

7 17 0 1.012234 -1.210570 -0.288519

15

8 9 0 0.324494 1.084631 -1.158077

9 1 0 0.144570 1.962235 1.228023

10 1 0 0.535834 0.394044 2.008384

stru. 2

1 6 0 -1.036137 0.753564 -0.024922

2 6 0 -1.401698 0.550191 1.379371

3 6 0 -0.045078 0.195836 -0.708016

4 6 0 -0.578456 0.307570 2.398302

5 1 0 -1.666682 1.407025 -0.619606

6 1 0 -2.464897 0.642391 1.580954

7 17 0 1.106429 -0.949303 -0.150959

8 9 0 0.141654 0.474584 -1.997383

9 1 0 0.495702 0.245021 2.277389

10 1 0 -0.973376 0.179960 3.398465

1b F-Br

Frequencies -- 149.1768 255.9505 318.4960





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.334380

3 6 0 1.496179 0.000000 -0.064296

4 6 0 1.512916 0.002405 1.484952

5 1 0 -0.749827 0.007329 -0.778374

6 1 0 -0.792194 0.015501 2.072087

7 9 0 2.065859 -1.098102 -0.631525

8 35 0 2.298178 1.566305 -0.922290

9 1 0 1.953170 0.887789 1.942994

10 1 0 1.953143 -0.905204 1.900490

TS1bin F-Br-ts F-inward

Frequencies -- -675.0412 171.1218 229.1909





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.384611

3 6 0 1.377343 0.000000 -0.283261

4 6 0 1.218415 0.582491 1.778838

5 1 0 -0.800536 0.094433 -0.722791

6 1 0 -0.730532 -0.449396 2.050816

7 9 0 2.168723 -1.061174 -0.035794

8 35 0 2.041547 0.887188 -1.844619

9 1 0 1.482419 1.553663 1.384952

10 1 0 1.740983 0.287637 2.686981






stru. 1

16

1 6 0 -1.190872 0.249613 0.937540

2 6 0 -1.623618 -0.088020 2.296814

3 6 0 -0.050515 -0.109529 0.359075

4 6 0 -1.021283 -0.890708 3.177203

5 1 0 -1.854032 0.855994 0.335316

6 1 0 -2.556442 0.384707 2.589427

7 9 0 0.873068 -0.843866 0.968571

8 35 0 0.457051 0.346192 -1.390935

9 1 0 -0.094903 -1.407640 2.967544

10 1 0 -1.469054 -1.048626 4.150532

stru. 2

1 6 0 -1.590447 -0.702194 0.720900

2 6 0 -1.634163 -0.005357 1.858166

3 6 0 -0.114443 -0.495828 0.574981

4 6 0 -0.146979 0.304792 1.901565

5 1 0 -2.305686 -1.219396 0.097345

6 1 0 -2.442392 0.269915 2.524193

7 9 0 0.653102 -1.617964 0.609029

8 35 0 0.426421 0.523344 -1.006522

9 1 0 0.136487 1.353463 1.820697

10 1 0 0.416472 -0.185356 2.696989

TS1bout Br-F-ts Br-inward

Frequencies -- -595.7911 187.9116 223.4353





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.381955

3 6 0 1.366647 0.000000 -0.326626

4 6 0 1.238521 0.533396 1.779041

5 1 0 -0.803500 0.083906 -0.722638

6 1 0 -0.739594 -0.436473 2.044735

7 35 0 2.533385 -1.518755 -0.150251

8 9 0 1.756848 0.666226 -1.423594

9 1 0 1.539952 1.498357 1.397611

10 1 0 1.753671 0.209429 2.682168



IRC fibnal structures

stru. 1

1 6 0 -1.848625 0.353115 0.062669

2 6 0 -1.914695 0.928495 1.265012

3 6 0 -0.389358 0.658168 -0.075323

4 6 0 -0.451307 1.338718 1.315509

5 1 0 -2.536424 -0.161975 -0.592176

6 1 0 -2.716836 1.054727 1.980214

7 35 0 0.779053 -0.910050 -0.187183

8 9 0 -0.044250 1.487944 -1.096046

9 1 0 -0.254403 2.410633 1.265309

10 1 0 0.156495 0.873040 2.090390

stru. 2

1 6 0 -1.315578 1.196492 0.060086

17

2 6 0 -1.705458 0.951984 1.451772

3 6 0 -0.372262 0.597066 -0.653790

4 6 0 -0.889044 0.692367 2.470577

5 1 0 -1.885190 1.934788 -0.498155

6 1 0 -2.771805 1.035291 1.641699

7 35 0 0.762541 -0.802297 -0.131982

8 9 0 -0.157249 0.941219 -1.923494

9 1 0 0.186045 0.640510 2.351697

10 1 0 -1.286856 0.536372 3.465678

1c Cl-Br

Frequencies -- 148.9661 221.1986 250.9802





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.333598

3 6 0 1.495007 0.000000 -0.082448

4 6 0 1.510681 0.002744 1.475640

5 1 0 -0.745972 -0.000127 -0.782311

6 1 0 -0.790454 0.003027 2.072935

7 17 0 2.213747 -1.448128 -0.838651

8 35 0 2.251288 1.608283 -0.901148

9 1 0 1.950986 0.897293 1.916322

10 1 0 1.954136 -0.894521 1.908216

TS1cin Cl-Br-ts Cl-inward

Frequencies -- -632.6326 171.9890 222.1517





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.380170

3 6 0 1.372040 0.000000 -0.332864

4 6 0 1.238948 0.539550 1.772238

5 1 0 -0.810392 0.093442 -0.713225

6 1 0 -0.742491 -0.423632 2.048892

7 17 0 2.411141 -1.409619 -0.132124

8 35 0 1.904940 1.016289 -1.869264

9 1 0 1.545980 1.496492 1.374380

10 1 0 1.757706 0.220802 2.675168






stru. 1

1 6 0 -1.653772 -0.523656 0.692222

2 6 0 -1.681432 0.134750 1.851394

3 6 0 -0.187061 -0.293441 0.501217

4 6 0 -0.203669 0.479295 1.854428

5 1 0 -2.368566 -1.046128 0.072486

6 1 0 -2.472016 0.356660 2.556448

18

7 17 0 0.816522 -1.770463 0.494370

8 35 0 0.260915 0.804450 -1.053797

9 1 0 0.045492 1.537047 1.768468

10 1 0 0.396878 0.007550 2.632808

stru. 2

1 6 0 -1.116316 0.345733 1.022186

2 6 0 -1.536433 -0.170747 2.329719

3 6 0 -0.131558 -0.087658 0.235799

4 6 0 -0.756819 -0.672214 3.286420

5 1 0 -1.708487 1.160706 0.619385

6 1 0 -2.602395 -0.079825 2.519172

7 17 0 0.906363 -1.420285 0.586876

8 35 0 0.203005 0.726874 -1.439912

9 1 0 0.317456 -0.748797 3.180270

10 1 0 -1.187804 -1.006129 4.222287

TS1cout Br-Cl-ts Br-inward

Frequencies -- -618.3863 174.8776 208.9335





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.380282

3 6 0 1.369832 0.000000 -0.338722

4 6 0 1.243387 0.528790 1.771782

5 1 0 -0.809598 0.090385 -0.715199

6 1 0 -0.742839 -0.422881 2.048569

7 35 0 2.499957 -1.550374 -0.117031

8 17 0 1.872016 0.914565 -1.745465

9 1 0 1.557013 1.485287 1.378084

10 1 0 1.761019 0.203878 2.673344




stru. 1

1 6 0 -1.843056 0.189414 0.234852

2 6 0 -1.900701 0.811767 1.412885

3 6 0 -0.382111 0.470583 0.064364

4 6 0 -0.434530 1.200313 1.440185

5 1 0 -2.535838 -0.337024 -0.406314

6 1 0 -2.701976 0.984491 2.119714

7 35 0 0.747027 -1.125134 0.038547

8 17 0 0.031339 1.517104 -1.321647

9 1 0 -0.218755 2.267330 1.376155

10 1 0 0.172660 0.734047 2.215927

stru. 2

1 6 0 -1.286954 1.073340 0.384872

2 6 0 -1.732020 0.673071 1.724372

3 6 0 -0.332088 0.540839 -0.375309

4 6 0 -0.959274 0.290560 2.738710

5 1 0 -1.833289 1.892000 -0.075577

6 1 0 -2.803605 0.757480 1.883520

7 35 0 0.725116 -0.952877 0.079897

19

8 17 0 0.013182 1.181682 -1.950311

9 1 0 0.118704 0.234203 2.655234

10 1 0 -1.397391 0.037182 3.696039

1d F-F

Frequencies -- 181.9022 332.0805 463.5757





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.334270

3 6 0 1.501968 0.000000 -0.052370

4 6 0 1.515273 -0.000165 1.491390

5 1 0 -0.756108 0.000407 -0.772637

6 1 0 -0.793129 0.000126 2.070711

7 9 0 2.078687 -1.084856 -0.631276

8 9 0 2.078564 1.085116 -0.630949

9 1 0 1.952968 0.897454 1.929566

10 1 0 1.952828 -0.897846 1.929597

TS1d F-F-ts

Frequencies -- -651.5445 246.0325 276.5491





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.385278

3 6 0 1.373756 0.000000 -0.285239

4 6 0 1.221186 0.569654 1.786696

5 1 0 -0.796031 0.104192 -0.726889

6 1 0 -0.739314 -0.443708 2.044663

7 9 0 2.181062 -1.043801 -0.070149

8 9 0 1.838978 0.617629 -1.369563

9 1 0 1.483165 1.547377 1.407980

10 1 0 1.735945 0.269472 2.697347




stru.1

1 6 0 -1.278797 -0.297494 -0.086369

2 6 0 -1.321587 0.255698 1.127000

3 6 0 0.199841 -0.054513 -0.202882

4 6 0 0.164179 0.583754 1.202856

5 1 0 -1.997943 -0.749125 -0.755403

6 1 0 -2.124954 0.423146 1.832467

7 9 0 0.980684 -1.160169 -0.312987

8 9 0 0.588932 0.780487 -1.201020

9 1 0 0.424036 1.643012 1.214625

10 1 0 0.738179 0.036397 1.951555

stru.2

1 6 0 -0.913165 0.398558 -0.098420

2 6 0 -1.175673 0.345603 1.341538

3 6 0 0.192876 0.004303 -0.707436

20

4 6 0 -0.381173 -0.128040 2.303182

5 1 0 -1.677479 0.792605 -0.754378

6 1 0 -2.143845 0.744513 1.627177

7 9 0 1.255334 -0.502804 -0.119514

8 9 0 0.391714 0.063809 -2.008485

9 1 0 0.598148 -0.544027 2.106129

10 1 0 -0.711710 -0.104933 3.333881

1e Cl-Cl

Frequencies -- 160.1446 266.0103 267.7204





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.333130

3 6 0 1.497399 0.000000 -0.081701

4 6 0 1.510951 0.001042 1.475573

5 1 0 -0.745874 -0.000554 -0.782546

6 1 0 -0.790450 -0.000509 2.072314

7 17 0 2.208413 -1.459594 -0.832344

8 17 0 2.210712 1.456446 -0.835587

9 1 0 1.952342 0.897942 1.910626

10 1 0 1.953814 -0.894388 1.912144

TS1e Cl-Cl-ts

Frequencies -- -630.6632 186.9043 235.0402





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.380134

3 6 0 1.372497 0.000000 -0.331687

4 6 0 1.238017 0.541945 1.771819

5 1 0 -0.807978 0.091767 -0.716520

6 1 0 -0.741948 -0.424379 2.048688

7 17 0 2.408671 -1.413333 -0.117193

8 17 0 1.884666 0.912571 -1.737057

9 1 0 1.540993 1.501084 1.376276

10 1 0 1.758155 0.224129 2.674310




stru. 1

1 6 0 -1.553392 -0.229938 0.256018

2 6 0 -1.594611 0.387883 1.436746

3 6 0 -0.085692 0.022672 0.082098

4 6 0 -0.119772 0.745099 1.461841

5 1 0 -2.258738 -0.737966 -0.386229

6 1 0 -2.390678 0.575482 2.145211

7 17 0 0.931542 -1.447831 0.034596

8 17 0 0.335955 1.075414 -1.300885

9 1 0 0.120364 1.807426 1.409524

10 1 0 0.479418 0.254616 2.229514

21

stru. 2

1 6 0 -1.034566 0.681189 0.389812

2 6 0 -1.474844 0.322376 1.740999

3 6 0 -0.044197 0.167677 -0.339391

4 6 0 -0.752857 -0.193566 2.737265

5 1 0 -1.616940 1.445596 -0.111417

6 1 0 -2.519481 0.547638 1.929167

7 17 0 1.011326 -1.100182 0.161449

8 17 0 0.269056 0.730524 -1.950694

9 1 0 0.302177 -0.413582 2.649655

10 1 0 -1.222147 -0.394515 3.692370

1f Br-Br

Frequencies -- 139.5995 170.0888 240.6337





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.334053

3 6 0 1.492783 0.000000 -0.083299

4 6 0 1.510275 -0.000875 1.475802

5 1 0 -0.746196 0.000421 -0.781993

6 1 0 -0.790470 0.000341 2.073528

7 35 0 2.256892 -1.596414 -0.906713

8 35 0 2.255492 1.598966 -0.903767

9 1 0 1.952465 0.894273 1.913752

10 1 0 1.951199 -0.897244 1.912553

TS1f Br-Br-ts

Frequencies -- -620.4469 161.4098 181.9885





1 6 0 0.000000 0.000000 0.000000

2 6 0 0.000000 0.000000 1.380348

3 6 0 1.369427 0.000000 -0.339810

4 6 0 1.243946 0.527271 1.772062

5 1 0 -0.812227 0.091121 -0.711766

6 1 0 -0.743053 -0.422576 2.048860

7 35 0 2.501783 -1.546296 -0.130623

8 35 0 1.890961 1.018226 -1.877984

9 1 0 1.561121 1.481573 1.375726

10 1 0 1.760688 0.201756 2.673907




stru. 1

1 6 0 -1.854231 -0.133776 0.579138

2 6 0 -1.902326 0.538028 1.730566

3 6 0 -0.394667 0.129558 0.389986

4 6 0 -0.433879 0.917469 1.734942

5 1 0 -2.553403 -0.682269 -0.035989

22

6 1 0 -2.700448 0.747481 2.431494

7 35 0 0.726280 -1.467615 0.415776

8 35 0 0.038470 1.214767 -1.173756

9 1 0 -0.210355 1.979478 1.632264

10 1 0 0.174059 0.474570 2.523887

stru. 2

1 6 0 -1.344525 0.711695 0.847152

2 6 0 -1.812611 0.217046 2.147835

3 6 0 -0.353050 0.250588 0.085875

4 6 0 -1.048910 -0.181287 3.162550

5 1 0 -1.900168 1.546721 0.429625

6 1 0 -2.891151 0.244744 2.277627

7 35 0 0.714161 -1.251676 0.486102

8 35 0 0.058974 1.085836 -1.561957

9 1 0 0.032095 -0.185473 3.104315

10 1 0 -1.497173 -0.503269 4.094658

download fileview on ChemRxivcycX-YNa9729d.pdf (920.45 KiB)

https://chemrxiv.org/ndownloader/files/16724714

https://chemrxiv.org/articles/Torquoselectivity_of_the_Ring-Opening_Reaction_of_3_3-Dihalosubstituted_Cyclobutenes_Lone_Pair_Repulsion_and_Cyclic_Orbital_Interaction/9178121/1?file=16724714

torquoselectivity of the ring-opening reaction of 3,3

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