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6 INTERVIEW: PROFESSOR PAUL VON RAGUÉ SCHLEYER

6 INTERVIEW: PROFESSOR PAUL VON RAGUÉ SCHLEYER

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Schleyer quickly became enamored with the power of ab initio computations

to tackle interesting organic problems. His enthusiasm for computational chemistry eventually led to his decision to move to Erlangen—they offered unlimited

(24/7) computer time, while Princeton’s counteroffer was just 2 h of computer

time per week. He left Erlangen in 1998 due to enforced retirement. However,

his adjunct status at the University of Georgia allowed for a smooth transition

back to the United States, where he now enjoys a very productive collaborative

relationship with Professor Fritz Schaefer.

Perhaps the problem that best represents how Schleyer exploits the power

of ab initio computational chemistry is the question of how to define and

measure aromaticity. Schleyer’s interest in the concept of aromaticity spans his

entire career. He was drawn to this problem because of the pervasive nature

of aromaticity across organic chemistry. Schleyer describes his motivation:

“Aromaticity is a central theme of organic chemistry. It is re-examined by each

generation of chemists. Changing technology permits that re-examination to

occur.” His direct involvement came about by Kutzelnigg’s development of

a computer code to calculate chemical shifts. Schleyer began the use of this

program in the 1980s and applied it first to structural problems. His group

“discovered in this manner many experimental structures that were incorrect.”

To assess aromaticity, Schleyer first computed the lithium chemical shifts in

complexes formed between lithium cation and the hydrocarbon of interest. The

lithium cation would typically reside above the aromatic ring and its chemical

shift would be affected by the magnetic field of the ring. While this met with

some success, Schleyer was frustrated by the fact that lithium was often not

positioned especially near the ring, let alone in the center of the ring. This led

to the development of NICS, where the virtual chemical shift can be computed

at any point in space. Schleyer advocated using the geometric center of the ring,

then later a point 1 Å above the ring center.

Over time, Schleyer came to refine the use of NICS, advocating an examination of NICS values on a grid of points. His most recent paper posits using just

the component of the chemical shift tensor perpendicular to the ring evaluated

at the center of the ring. This evolution reflects Schleyer’s continuing pursuit

of a simple measure of aromaticity. “Our endeavor from the beginning was to

select one NICS point that we could say characterizes the compound,” Schleyer

says. “The problem is that chemists want a number which they can associate

with a phenomenon rather than a picture. The problem with NICS was that it

was not soundly based conceptually from the beginning because cyclic electron

delocalization-induced ring current was not expressed solely perpendicular to

the ring. It’s only that component which is related to aromaticity.”

The majority of our discussion revolved around the definition of aromaticity.

Schleyer argues that “aromaticity can be defined perfectly well. It is the manifestation of cyclic electron delocalization which is expressed in various ways.

The problem with aromaticity comes in its quantitative definition. How big is



INTERVIEW: PROFESSOR PAUL VON RAGUÉ SCHLEYER



179



the aromaticity of a particular molecule? We can answer this using some properties. One of my objectives is to see whether these various quantities are related

to one another. That, I think, is still an open question.”

Schleyer further detailed this thought, “The difficulty in writing about aromaticity is that it is encrusted by two centuries of tradition, which you cannot

avoid. You have to stress the interplay of the phenomena. Energetic properties

are most important, but you need to keep in mind that aromaticity is only 5

percent of the total energy. But if you want to get as close to the phenomenon

as possible, then one has to go to the property most closely related, which is

magnetic properties.” This is why he focuses upon the use of NICS as an aromaticity measure. He is quite confident in his new NICS measure employing the

perpendicular component of the chemical shift tensor. “This new criteria is very

satisfactory,” he says. “Most people who propose alternative measures do not

do the careful step of evaluating them against some basic standard. We evaluate

against aromatic stabilization energies.”

Schleyer notes that his evaluation of the ASE of benzene is larger than many

other estimates. This results from the fact that, in his opinion, “all traditional

equations for its determination use tainted molecules. Cyclohexene is tainted

by hyperconjugation of about 10 kcal mol−1 . Even cyclohexane is very tainted,

in this case by 1,3-interactions.” An analogous complaint can be made about the

methods Schleyer himself employs: NICS is evaluated at some arbitrary point

or arbitrary set of points, the block-diagonalized “cyclohexatriene” molecule is

a gedanken molecule. When pressed on what then to use as a reference that is

not ‘tainted’, Schleyer made this trenchant comment: “What we are trying to

measure is virtual. Aromaticity, like almost all concepts in organic chemistry,

is virtual. They’re not measurable. You can’t measure atomic charges within

a molecule. Hyperconjugation, electronegativity, everything is in this sort of

virtual category. Chemists live in a virtual world. But science moves to higher

degrees of refinement.” Despite its inherent ‘virtual’ nature, “Aromaticity has

this 200 year history. Chemists are interested in the unusual stability and reactivity associated with aromatic molecules. The term survives, and remains an

enormously fruitful area of research.”

His interest in the annulenes is a natural extension of the quest for understanding aromaticity. Schleyer was particularly drawn to [18]-annulene because it can

express the same D6h symmetry as does benzene. His computed chemical shifts

for the D6h structure differed significantly from the experimental values, indicating that the structure was clearly wrong. “It was an amazing computational

exercise,” Schleyer mused, “because practically every level you used to optimize the geometry gave a different structure. MP2 overshot the aromaticity, HF

and B3LYP undershot it. Empirically, we had to find a level that worked. This

was not very intellectually satisfying but was a pragmatic solution.” Schleyer

expected a lot of flak from crystallographers about this result, but in fact none

occurred. He hopes that the X-ray structure will be redone at some point.



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Reflecting on the progress of computational chemistry, Schleyer recalls that

“physical organic chemists were actually antagonistic toward computational

chemistry at the beginning. One of my friends said that he thought I had gone

mad. In addition, most theoreticians disdained me as a black-box user.” In those

early years as a computational chemist, Schleyer felt disenfranchised from

the physical organic chemistry community. Only slowly has he felt accepted

back into this camp. “Physical organic chemists have adopted computational

chemistry; perhaps, I hope to think, due to my example demonstrating what

can be done. If you can show people that you can compute chemical properties,

like chemical shifts to an accuracy that is useful, computed structures that are

better than experiment, then they get the word sooner or later that maybe you’d

better do some calculations.” In fact, Schleyer considers this to be his greatest

contribution to science—demonstrating by his own example the importance of

computational chemistry toward solving relevant chemical problems. He cites

his role in helping to establish the Journal of Computational Chemistry in both

giving name to the discipline and stature to its practitioners.

Schleyer looks to the future of computational chemistry residing in the

breadth of the periodic table. “Computational work has concentrated on one

element, namely carbon,” Schleyer says. “The rest of the periodic table is

waiting to be explored.” On the other hand, he is dismayed by the state of

research at universities. In his opinion, “the function of universities is to do

pure research, not to do applied research. Pure research will not be carried out

at any other location.” Schleyer sums up his position this way—“Pure research

is like putting money in the bank. Applied research is taking the money out.”

According to this motto, Schleyer’s account is very much in the black.



REFERENCES

1. Feng, Y.; Liu, L.; Wang, J.-T.; Huang, H.; Guo, Q.-X. “Assessment of experimental

bond dissociation energies using composite ab initio methods and evaluation of the

performances of density functional methods in the calculation of bond dissociation

energies,” J. Chem. Inf. Comput. Sci. 2003, 43, 2005–2013.

2. Blanksby, S. J.; Ellison, G. B. “Bond dissociation energies of organic molecules,” Acc.

Chem. Res. 2003, 36, 255–263.

3. Henry, D. J.; Parkinson, C. J.; Mayer, P. M.; Radom, L. “Bond dissociation energies

and radical stabilization energies associated with substituted methyl radicals,” J. Phys.

Chem. A 2001, 105, 6750–6756.

4. Feng, Y.; Liu, L.; Wang, J.-T.; Zhao, S.-W.; Guo, Q.-X. “Homolytic C–H and N–H

bond dissociation energies of strained organic compounds,” J. Org. Chem. 2004, 69,

3129–3138.

5. Menon, A. S.; Wood, G. P. F.; Moran, D.; Radom, L. “Bond dissociation energies and

radical stabilization energies: an assessment of contemporary theoretical procedures,”

J. Phys. Chem. A 2007, 111, 13638–13644.



REFERENCES



181



6. Yao, X.-Q.; Hou, X.-J.; Jiao, H.; Xiang, H.-W.; Li, Y.-W. “Accurate calculations of

bond dissociation enthalpies with density functional methods,” J. Phys. Chem. A 2003,

107, 9991–9996.

7. Check, C. E.; Gilbert, T. M. “Progressive systematic underestimation of reaction

energies by the B3LYP model as the number of C–C bonds increases: why organic

chemists should use multiple DFT models for calculations involving polycarbon

hydrocarbons,” J. Org. Chem. 2005, 70, 9828–9834.

8. Redfern, P. C.; Zapol, P.; Curtiss, L. A.; Raghavachari, K. “Assessment of Gaussian-3

and density functional theories for enthalpies of formation of C1 -C16 alkanes,” J. Phys.

Chem. A 2000, 104, 5850–5854.

9. Luo, Y.-R. Handbook of Bond Dissociation Energies in Organic Compounds; CRC

Press: New York, 2002.

10. Rüchardt, C. “Relations between structure and reactivity in free-radical chemistry,”

Angew. Chem. Int. Ed. Engl. 1970, 9, 830–843.

11. Izgorodina, E. I.; Coote, M. L.; Radom, L. “Trends in R–X bond dissociation energies

(R = Me, Et, i-Pr, t-Bu; X = H, CH3 , OCH3 , OH, F): a surprising shortcoming of

density functional theory,” J. Phys. Chem. A 2005, 109, 7558–7566.

12. Coote, M. L.; Pross, A.; Radom, L. “Variable trends in R–X bond dissociation energies

(R = Me, Et, i-Pr, t-Bu),” Org. Lett. 2003, 5, 4689–4692.

13. Matsunaga, N.; Rogers, D. W.; Zavitsas, A. A. “Pauling’s electronegativity equation

and a new corollary accurately predict bond dissociation enthalpies and enhance

current understanding of the nature of the chemical bond,” J. Org. Chem. 2003, 68,

3158–3172.

14. Lias, S. G.; Bartmess, J. E.; Holmes, J. L.; Levin, R. D.; Mallard, W. G. “Gas-phase

ion and neutral thermochemistry,” J. Phys. Chem. Ref. Data 1988, Suppl. 17.

15. Linstrom, P. J.; Mallard, W. G. “NIST chemistry webBook, NIST standard reference

database number 69,” 2012, URL: http://webbook.nist.gov

16. Kollmar, H. “The stability of alkyl anions. A molecular orbital theoretical study,” J.

Am. Chem. Soc. 1978, 100, 2665–2669.

17. Chandrasekhar, J.; Andrade, J. G.; Schleyer, P. v. R. “Efficient and accurate calculation

of anion proton affinities,” J. Am. Chem. Soc. 1981, 103, 5609–5612.

18. Saunders, W. H., Jr. “Ab initio and semi-empirical investigation of gas-phase carbon

acidity,” J. Phys. Org. Chem. 1994, 7, 268–271.

19. Burk, P.; Koppel, I. A.; Koppel, I.; Leito, I.; Travnikova, O. “Critical test of performance of B3LYP functional for prediction of gas-phase acidities and basicities,” Chem.

Phys. Lett. 2000, 323, 482–489.

20. Merrill, G. N.; Kass, S. R. “Calculated gas-phase acidities using density functional

theory: is it reliable?,” J. Phys. Chem. 1996, 100, 17465–17471.

21. Ochterski, J. W.; Petersson, G. A.; Montgomery, J. A., Jr. “A complete basis set model

chemistry. V. Extensions to six or more heavy atoms,” J. Chem. Phys. 1996, 104,

2598–2619.

22. Ochterski, J. W.; Petersson, G. A.; Wiberg, K. B. “A comparison of model

chemistries,” J. Am. Chem. Soc. 1995, 117, 11299–11308.

23. Topol, I. A.; Tawa, G. J.; Caldwell, R. A.; Eissenstat, M. A.; Burt, S. K. “Acidity of

organic molecules in the gas phase and in aqueous solvent,” J. Phys. Chem. A 2000,

104, 9619–9624.



182



FUNDAMENTALS OF ORGANIC CHEMISTRY



24. DePuy, C. H.; Gronert, S.; Barlow, S. E.; Bierbaum, V. M.; Damrauer, R. “The

gas-phase acidities of the alkanes,” J. Am. Chem. Soc. 1989, 111, 1968–1973.

25. Luh, T.-Y.; Stock, L. M. “Kinetic acidity of cubane,” J. Am. Chem. Soc. 1974, 96,

3712–3713.

26. Ritchie, J. P.; Bachrach, S. M. “Comparison of the calculated acidity of cubane with

that of other strained and unstrained hydrocarbons,” J. Am. Chem. Soc. 1990, 112,

6514–6517.

27. Hare, M.; Emrick, T.; Eaton, P. E.; Kass, S. R. “Cubyl anion formation and an experimental determination of the acidity and C–H bond dissociation energy of cubane,” J.

Am. Chem. Soc. 1997, 119, 237–238.

28. Rayne, S.; Forest, K. “Gas-phase enthalpies of formation, acidities, and strain energies

of the [m,n]polyprismanes (m ≥ 2; n = 3–8; m × n ≤ 16): a CBS-Q//B3, G4MP2, and

G4 theoretical study,” Theor. Chem. Acc. 2010, 127, 697–709.

29. Broadus, K. M.; Kass, S. R.; Osswald, T.; Prinzbach, H. “Dodecahedryl anion formation and an experimental determination of the acidity and C–H bond dissociation

energy of dodecahedrane,” J. Am. Chem. Soc. 2000, 122, 10964–10968.

30. Fattahi, A.; McCarthy, R. E.; Ahmad, M. R.; Kass, S. R. “Why does cyclopropene

have the acidity of an acetylene but the bond energy of methane?,” J. Am. Chem. Soc.

2003, 125, 11746–11750.

31. Manini, P.; Amrein, W.; Gramlich, V.; Diederich, F. “Expanded cubane: synthesis of a

cage compound with a C56 core by acetylenic scaffolding and gas-phase transformations into fullerenes,” Angew. Chem. Int. Ed. 2002, 4339–4343.

32. Bachrach, S. M. “Structure, deprotonation energy, and cation affinity of an

ethynyl-expanded cubane,” J. Phys. Chem. A 2003, 107, 4957–4961.

33. Bachrach, S. M.; Demoin, D. W. “Computational studies of ethynyl- and

diethynyl-expanded tetrahedranes, prismanes, cubanes, and adamantanes,” J. Org.

Chem. 2006, 71, 5105–5116.

34. de Visser, S. P.; van der Horst, E.; de Koning, L. J.; van der Hart, W. J.; Nibbering,

N. M. M. “Characterization of isomeric C4 H5 − anions in the gas phase; theory and

experiment,” J. Mass Spectrom. 1999, 34, 303–310.

35. Siggel, M. R.; Thomas, T. D. “Why are organic acids stronger acids than organic alcohols?,” J. Am. Chem. Soc. 1986, 108, 4360–4363.

36. Burk, P.; Schleyer, P. v. R. “Why are carboxylic acids stronger acids than alcohols?

The electrostatic theory of Siggel–Thomas revisited,” J. Mol. Struct. (THEOCHEM)

2000, 505, 161–167.

37. Siggel, M. R. F.; Streitwieser, A. J.; Thomas, T. D. “The role of resonance and inductive

effects in the acidity of carboxylic acids,” J. Am. Chem. Soc. 1988, 110, 8022–8028.

38. Exner, O. “Why are carboxylic acids and phenols stronger acids than alcohols?,” J.

Org. Chem. 1988, 53, 1810–1812.

39. Dewar, M. J. S.; Krull, K. L. “Acidity of carboxylic acids: due to delocalization or

induction?,” J. Chem. Soc., Chem. Commun. 1990, 333–334.

40. Perrin, C. L. “Atomic size dependence of Bader electron populations: significance for

questions of resonance stabilization,” J. Am. Chem. Soc. 1991, 113, 2865–2868.

41. Hiberty, P. C.; Byrman, C. P. “Role of π-electron delocalization in the enhanced acidity of carboxylic acids and enols relative to alcohols,” J. Am. Chem. Soc. 1995, 117,

9875–9880.



REFERENCES



183



42. Rablen, P. R. “Is the acetate anion stabilized by resonance or electrostatics? A systematic structural comparison,” J. Am. Chem. Soc. 2000, 122, 357–368.

43. Holt, J.; Karty, J. M. “Origin of the acidity enhancement of formic acid over methanol:

resonance versus inductive effects,” J. Am. Chem. Soc. 2003, 125, 2797–2803.

44. O’Hair, R. A. J.; Bowie, J. H.; Gronert, S. “Gas phase acidities of the 𝛼- amino acids,”

Int. J. Mass Spectrom. Ion Processes 1992, 117, 23–36.

45. Jones, C. M.; Bernier, M.; Carson, E.; Colyer, K. E.; Metz, R.; Pawlow, A.; Wischow,

E. D.; Webb, I.; Andriole, E. J.; Poutsma, J. C. “Gas-phase acidities of the 20 protein

amino acids,” Int. J. Mass Spectrom. 2007, 267, 54–62.

46. Tian, Z.; Pawlow, A.; Poutsma, J. C.; Kass, S. R. “Are carboxyl groups the most acidic

sites in amino acids? Gas-phase acidity, H/D exchange experiments, and computations

on cysteine and its conjugate base,” J. Am. Chem. Soc. 2007, 129, 5403–5407.

47. Tian, Z.; Wang, X.-B.; Wang, L.-S.; Kass, S. R. “Are carboxyl groups the most acidic

sites in amino acids? Gas-phase acidities, photoelectron spectra, and computations on

tyrosine, p-hydroxybenzoic acid, and their conjugate bases,” J. Am. Chem. Soc. 2009,

131, 1174–1181.

48. Smith, G. D.; Jaffe, R. L. “Quantum chemistry study of conformational energies and

rotational energy barriers in n-alkanes,” J. Phys. Chem. 1996, 100, 18718–18724.

49. Gruzman, D.; Karton, A.; Martin, J. M. L. “Performance of Ab initio and density functional methods for conformational equilibria of Cn H2n+2 alkane isomers (n = 4–8),”

J. Phys. Chem. A 2009, 113, 11974–11983.

50. Allinger, N. L.; Fermann, J. T.; Allen, W. D.; Schaefer Iii, H. F. “The torsional conformations of butane: definitive energetics from ab initio methods,” J. Chem. Phys. 1997,

106, 5143–5150.

51. Herrebout, W. A.; van der Veken, B. J.; Wang, A.; Durig, J. R. “Enthalpy difference

between conformers of n-butane and the potential function governing conformational

interchange,” J. Phys. Chem. 1995, 99, 578–585.

52. Balabin, R. M. “Enthalpy difference between conformations of normal alkanes:

Raman spectroscopy study of n-pentane and n-butane,” J. Phys. Chem. A 2009, 113,

1012–1019.

53. Martin, J. M. L.; de Oliveira, G. “Towards standard methods for benchmark quality ab

initio thermochemistry—W1 and W2 theory,” J. Chem. Phys. 1999, 111, 1843–1856.

54. Parthiban, S.; Martin, J. M. L. “Assessment of W1 and W2 theories for the computation

of electron affinities, ionization potentials, heats of formation, and proton affinities,”

J. Chem. Phys. 2001, 114, 6014–6029.

55. Balabin, R. M. “Enthalpy difference between conformations of normal alkanes: effects

of basis set and chain length on intramolecular basis set superposition error,” Mol.

Phys. 2011, 109, 943–953.

56. Asturiol, D.; Duran, M.; Salvador, P. “Intramolecular basis set superposition error

effects on the planarity of benzene and other aromatic molecules: a solution to the

problem,” J. Chem. Phys. 2008, 128, 144108.

57. Császár, A. G. “Conformers of gaseous α-alanine,” J. Phys. Chem. 1996, 100,

3541–3551.

58. Godfrey, P. D.; Firth, S.; Hatherley, L. D.; Brown, R. D.; Pierlot, A. P.

“Millimeter-wave spectroscopy of biomolecules: alanine,” J. Am. Chem. Soc. 1993,

115, 9687–9691.



184



FUNDAMENTALS OF ORGANIC CHEMISTRY



59. Jaeger, H. M.; Schaefer, H. F.; Demaison, J.; Császár, A. G.; Allen, W. D.

“Lowest-lying conformers of alanine: pushing theory to ascertain precise energetics

and semiexperimental Re structures,” J. Chem. Theory Comput. 2010, 6, 3066–3078.

60. Blanco, S.; Lesarri, A.; López, J. C.; Alonso, J. L. “The gas-phase structure of alanine,”

J. Am. Chem. Soc. 2004, 126, 11675–11683.

61. Gronert, S.; O’Hair, R. A. J. “Ab initio studies of amino acid conformations. 1. The

conformers of alanine, serine, and cysteine,” J. Am. Chem. Soc. 1995, 117, 2071–2081.

62. Dobrowolski, J. C.; Rode, J. E.; Sadlej, J. “Cysteine conformations revisited,” J. Mol.

Struct. (THEOCHEM) 2007, 810, 129–134.

63. Sanz, M. E.; Blanco, S.; López, J. C.; Alonso, J. L. “Rotational probes of six conformers of neutral cysteine,” Angew. Chem. Int. Ed. 2008, 47, 6216–6220.

64. Wilke, J. J.; Lind, M. C.; Schaefer, H. F.; Császár, A. G.; Allen, W. D. “Conformers

of gaseous cysteine,” J. Chem. Theor. Comput. 2009, 5, 1511–1523.

65. Grimme, S. “Seemingly simple stereoelectronic effects in alkane isomers and the

implications for Kohn-Sham density functional theory,” Angew. Chem. Int. Ed. 2006,

45, 4460–4464.

66. NIST. “NIST chemistry webBook,” 2005, URL: http://webbook.nist.gov/

67. Zhao, Y.; Truhlar, D. G. “A density functional that accounts for medium-range correlation energies in organic chemistry,” Org. Lett. 2006, 8, 5753–5755.

68. Schreiner, P. R.; Fokin, A. A.; Pascal, R. A.; DeMeijere, a. “Many density functional

theory approaches fail to give reliable large hydrocarbon isomer energy differences,”

Org. Lett. 2006, 8, 3635–3638.

69. Wodrich, M. D.; Corminboeuf, C.; Schleyer, P. v. R. “Systematic errors in computed

alkane energies using B3LYP and other popular DFT functionals,” Org. Lett. 2006, 8,

3631–3634.

70. Wodrich, M. D.; Corminboeuf, C.; Schreiner, P. R.; Fokin, A. A.; Schleyer, P. v.

R. “How accurate are DFT treatments of organic energies?,” Org. Lett. 2007, 9,

1851–1854.

71. Pieniazek, S. N.; Clemente, F. R.; Houk, K. N. “Sources of error in DFT computations

of C–C bond formation thermochemistries: π→σ transformations and error cancellation by DFT methods,” Angew. Chem. Int. Ed. 2008, 47, 7746–7749.

72. Brittain, D. R. B.; Lin, C. Y.; Gilbert, A. T. B.; Izgorodina, E. I.; Gill, P. M. W.; Coote,

M. L. “The role of exchange in systematic DFT errors for some organic reactions,”

Phys. Chem. Chem. Phys. 2009, 11, 1138–1142.

73. Song, J.-W.; Tsuneda, T.; Sato, T.; Hirao, K. “Calculations of alkane energies using

long-range corrected DFT combined with intramolecular van der Waals correlation,”

Org. Lett. 2010, 12, 1440–1443.

74. Sato, T.; Nakai, H. “Density functional method including weak interactions: dispersion

coefficients based on the local response approximation,” J. Chem. Phys. 2009, 131,

224104–224112.

75. Grimme, S. “n-Alkane isodesmic reaction energy errors in density functional theory

are due to electron correlation effects,” Org. Lett. 2010, 12, 4670–4673.

76. Krieg, H.; Grimme, S. “Thermochemical benchmarking of hydrocarbon bond

separation reaction energies: Jacob’s ladder is not reversed!,” Mol. Phys. 2010, 108,

2655–2666.



REFERENCES



185



77. Zhao, Y.; Schultz, N. E.; Truhlar, D. G. “Design of density functionals by combining

the method of constraint satisfaction with parametrization for thermochemistry, thermochemical kinetics, and noncovalent interactions,” J. Chem. Theory Comput. 2006,

2, 364–382.

78. Zhao, Y.; Truhlar, D. “The M06 suite of density functionals for main group thermochemistry, thermochemical kinetics, noncovalent interactions, excited states, and

transition elements: two new functionals and systematic testing of four M06-class

functionals and 12 other functionals,” Theor. Chem. Acc. 2008, 120, 215–241.

79. Mardirossian, N.; Parkhill, J. A.; Head-Gordon, M. “Benchmark results for empirical post-GGA functionals: difficult exchange problems and independent tests,” Phys.

Chem. Chem. Phys. 2011, 13, 19325–19337.

80. Song, J.-W.; Tsuneda, T.; Sato, T.; Hirao, K. “An examination of density functional

theories on isomerization energy calculations of organic molecules,” Theor. Chem.

Acc. 2011, 130, 851–857.

81. Chai, J.-D.; Head-Gordon, M. “Systematic optimization of long-range corrected

hybrid density functionals,” J. Chem. Phys. 2008, 128, 084106–084115.

82. McBride, J. M. “The hexaphenylethane riddle,” Tetrahedron 1974, 30, 2009–2022.

83. Selwood, P. W.; Dobres, R. M. “The diamagnetic correction for free radicals,” J. Am.

Chem. Soc. 1950, 72, 3860–3863.

84. Kahr, B.; Van Engen, D.; Mislow, K. “Length of the ethane bond in hexaphenylethane

and its derivatives,” J. Am. Chem. Soc. 1986, 108, 8305–8307.

85. Grimme, S.; Schreiner, P. R. “Steric crowding can stabilize a labile molecule: solving

the hexaphenylethane riddle,” Angew. Chem. Int. Ed. 2011, 50, 12639–12642.

86. Schreiner, P. R.; Chernish, L. V.; Gunchenko, P. A.; Tikhonchuk, E. Y.; Hausmann, H.;

Serafin, M.; Schlecht, S.; Dahl, J. E. P.; Carlson, R. M. K.; Fokin, A. A. “Overcoming lability of extremely long alkane carbon-carbon bonds through dispersion forces,”

Nature 2011, 477, 308–311.

87. Fokin, A. A.; Chernish, L. V.; Gunchenko, P. A.; Tikhonchuk, E. Y.; Hausmann, H.;

Serafin, M.; Dahl, J. E. P.; Carlson, R. M. K.; Schreiner, P. R. “Stable alkanes containing very long carbon–carbon bonds,” J. Am. Chem. Soc. 2012, 134, 13641–13650.

88. Smith, M. B.; March, J. March’s Advanced Organic Chemistry: Reactions, Mechanisms, and Structure; Wiley: New York, 2001.

89. Pedley, J. B.; Naylor, R. D.; Kirby, S. P. Thermochemical Data of Organic Compounds;

2nd ed.; Chapman and Hall: London, 1986.

90. Benson, S. W.; Cruickshank, F. R.; Golden, D. M.; Haugen, G. R.; O’Neal, H. E.;

Rodgers, A. S.; Shaw, R.; Walsh, R. “Additivity rules for the estimation of thermochemical properties,” Chem. Rev. 1969, 69, 279–324.

91. Benson, S. W. Thermochemical Kinetics: Methods for the Estimation of Thermochemical Data and Rate Parameters; 2nd ed.; Wiley: New York, 1976.

92. Wiberg, K. B. “Group equivalents for converting ab initio energies to enthalpies of

formation,” J. Comp. Chem. 1984, 5, 197–199.

93. Ibrahim, M. R.; Schleyer, P. v. R. “Atom equivalents for relating ab initio energies to

enthalpies of formation,” J. Comp. Chem. 1985, 6, 157–167.

94. Cioslowski, J.; Liu, G.; Piskorz, P. “Computationally inexpensive theoretical thermochemistry,” J. Phys. Chem. A 1998, 102, 9890–9900.



186



FUNDAMENTALS OF ORGANIC CHEMISTRY



95. Guthrie, J. P. “Heats of formation from DFT calculations: an examination of several

parameterizations,” J. Phys. Chem. A 2001, 105, 9196–9202.

96. Hehre, W. J.; Ditchfield, R.; Radom, L.; Pople, J. A. “Molecular orbital theory of the

electronic structure of organic compounds. V. Molecular theory of bond separation,”

J. Am. Chem. Soc. 1970, 92, 4796–4801.

97. George, P.; Trachtman, M.; Bock, C. W.; Brett, A. M. “An alternative approach to the

problem of assessing destabilization energies (strain energies) in cyclic hydrocarbons,”

Tetrahedron 1976, 32, 317–323.

98. George, P.; Trachtman, M.; Brett, A. M.; Bock, C. W. “Comparison of various

isodesmic and homodesmotic reaction heats with values derived from published

ab initio molecular orbital calculations,” J. Chem. Soc., Perkin Trans. 2 1977,

1036–1047.

99. Bachrach, S. M. “The group equivalent reaction: an improved method for determining

ring strain energy,” J. Chem. Ed. 1990, 67, 907–908.

100. Wheeler, S. E.; Houk, K. N.; Schleyer, P. v. R.; Allen, W. D. “A hierarchy of homodesmotic reactions for thermochemistry,” J. Am. Chem. Soc. 2009, 131, 2547–2560.

101. Boatz, J. A.; Gordon, M. S.; Hilderbrandt, R. L. “Structure and bonding in cycloalkanes

and monosilacycloalkanes,” J. Am. Chem. Soc. 1988, 110, 352–358.

102. Alcamí, M.; Mó, O.; đez, M. “G2 ab initio calculations on three-membered rings:

role of hydrogen atoms,” J. Comp. Chem. 1998, 19, 1072–1086.

103. Cremer, D. “Pros and cons of σ-aromaticity,” Tetrahedron 1988, 44, 7427–7454.

104. Cremer, D.; Gauss, J. “Theoretical determination of molecular structure and conformation. 20. Reevaluation of the strain energies of cyclopropane and cyclobutane – CC

and CH bond energies, 1,3 interactions, and σ-aromaticity,” J. Am. Chem. Soc. 1986,

108, 7467–7477.

105. Baeyer, A. v. “Über polyacetylenverbindungen,” Chem. Ber. 1885, 18, 2269–2281.

106. Huisgen, R. “Adolf von Baeyer’s scientific achievements – a legacy,” Angew. Chem.

Int. Ed. Engl. 1986, 25, 297–311.

107. Snyder, R. G.; Schachtschneider, J. H. “A valence force field for saturated hydrocarbons,” Spectrochim. Acta 1965, 21, 169–195.

108. Walsh, A. D. “Structures of ethylene oxide, cyclopropane, and related molecules,”

Trans. Faraday Soc. 1949, 45, 179–190.

109. Bader, R. F. W. Atoms in Molecules – A Quantum Theory; Oxford University Press:

Oxford, 1990.

110. Pitzer, K. S. “Strain energies of cyclic hydrocarbons,” Science 1945, 101, 672.

111. Dunitz, J. D.; Schomaker, V. “The molecular structure of cyclobutane,” J. Chem. Phys.

1952, 20, 1703–1707.

112. Bauld, N. L.; Cessac, J.; Holloway, R. L. “1,3(Nonbonded) carbon/carbon interactions. The common cause of ring strain, puckering, and inward methylene rocking

in cyclobutane and of vertical nonclassical stabilization, pyramidalization, puckering,

and outward methylene rocking in the cyclobutyl cation,” J. Am. Chem. Soc. 1977, 99,

8140–8144.

113. Coulson, C. A.; Moffitt, W. E. “The properties of certain strained hydrocarbons,” Phil.

Mag. 1949, 40, 1–35.



REFERENCES



187



114. Baghal-Vayjooee, M. H.; Benson, S. W. “Kinetics and thermochemistry of the reaction

atomic chlorine + cyclopropane .dblarw. hydrochloric acid + cyclopropyl. Heat of

formation of the cyclopropyl radical,” J. Am. Chem. Soc. 1979, 101, 2838–2840.

115. Seakins, P. W.; Pilling, M. J.; Niiranen, J. T.; Gutman, D.; Krasnoperov, L. N. “Kinetics

and thermochemistry of R + HBr .dblarw. RH + Br reactions: determinations of the

heat of formation of C2 H5 , i-C3 H7 , sec-C4 H9 and t-C4 H9 ,” J. Phys. Chem. 1992, 96,

9847–9855.

116. Exner, K.; Schleyer, P. v. R. “Theoretical bond energies: a critical evaluation,” J. Phys.

Chem. A 2001, 105, 3407–3416.

117. Grimme, S. “Theoretical bond and strain energies of molecules derived from properties

of the charge density at bond critical points,” J. Am. Chem. Soc. 1996, 118, 1529–1534.

118. Johnson, W. T. G.; Borden, W. T. “Why are methylenecyclopropane and

1-methylcylopropene more “strained” than methylcyclopropane?,” J. Am. Chem. Soc.

1997, 119, 5930–5933.

119. Bach, R. D.; Dmitrenko, O. “The effect of substitutents on the strain energies of small

ring compounds,” J. Org. Chem. 2002, 67, 2588–2599.

120. Bach, R. D.; Dmitrenko, O. “Strain energy of small ring hydrocarbons. Influence of

C–H bond dissociation energies,” J. Am. Chem. Soc. 2004, 126, 4444–4452.

121. Dewar, M. J. S. “σ-Conjugation and σ-aromaticity,” Bull. Soc. Chim. Belg. 1979, 88,

957–967.

122. Dewar, M. J. S. “Chemical implications of 𝜎 conjugation,” J. Am. Chem. Soc. 1984,

106, 669–682.

123. Kraka, E.; Cremer, D. “Theoretical determination of molecular structure and conformation. 15. Three-membered rings: bent bonds, ring strain, and surface delocalization,” J. Am. Chem. Soc. 1985, 107, 3800–3810.

124. Moran, D.; Manoharan, M.; Heine, T.; Schleyer, P. v. R. “σ-Antiaromaticity in cyclobutane, cubane, and other molecules with saturated four-membered rings,” Org. Lett.

2003, 5, 23–26.

125. Fowler, P. W.; Baker, J.; Mark Lillington, M. “The ring current in cyclopropane” Theor.

Chem. Acta 2007, 118, 123–127.

126. Schleyer, P. v. R.; Jiao, H. “What is aromaticity?,” Pure. Appl. Chem. 1996, 68,

209–218.

127. Krygowski, T. M.; Cyrañski, M. K.; Czarnocki, Z.; Häfelinger, G.; Katritzky, A. R.

“Aromaticity: a theoretical concept of immense practical importance,” Tetrahedron

2000, 56, 1783–1796.

128. Stanger, A. “What is … aromaticity: a critique of the concept of aromaticity – can it

really be defined?,” Chem. Commun. 2009, 1939–1947.

129. Minkin, V. I.; Glukhovtsev, M. N.; Simkin, B. Y. Aromaticity and Antiaromaticity:

Electronic and Structural Aspects; John Wiley & Sons: New York, 1994.

130. Schleyer, P. v. R. “Aromaticity,” Chem. Rev. 2001, 101, 1115–1566.

131. Cyranski, M. K. “Energetic aspects of cyclic Pi-electron delocalization: evaluation

of the methods of estimating aromatic stabilization energies,” Chem. Rev. 2005, 105,

3773–3811.

132. Cyranski, M. K.; Schleyer, P. v. R.; Krygowski, T. M.; Jiao, H.; Hohlneicher, G. “Facts

and artifacts about aromatic stability estimation,” Tetrahedron 2003, 59, 1657–1665.



188



FUNDAMENTALS OF ORGANIC CHEMISTRY



133. Hedberg, L.; Hedberg, K.; Cheng, P.-C.; Scott, L. T. “Gas-phase molecular structure

of corannulene, C20H10. An electron-diffraction study augmented by ab initio and

normal coordinate calculations,” J. Phys. Chem. A 2000, 104, 7689–7694.

134. Dobrowolski, M. A.; Ciesielski, A.; Cyranski, M. K. “On the aromatic stabilization of

corannulene and coronene,” Phys. Chem. Chem. Phys. 2011, 13, 20557–20563.

135. Choi, C. H.; Kertesz, M. “Bond length alternation and aromaticity in large annulenes,”

J. Chem. Phys. 1998, 108, 6681–6688.

136. Aromaticity, Pseudo-Aromaticity, Anti-Aromaticity, Proceedings of an International

Symposium; Bergmann, E. D.; Pullman, B., Eds.; Israel Academy of Sciences and

Humanities: Jerusalem, 1971; Vol. 33 see the following exchange: E. Heilbronner:

“Now could you point out a molecule, except benzene, which classifies as ‘aromatic’?”

B. Binsch: “Benzene is a perfect example!” E. Heilbronner: “Name a second one.” B.

Binsch: “It is, of course, a question of degree”.

137. Katritzky, A. R.; Barczynski, P.; Musumarra, G.; Pisano, D.; Szafran, M. “Aromaticity

as a quantitative concept. 1. A statistical demonstration of the orthogonality of classical

and magnetic aromaticity in five- and six-membered heterocycles,” J. Am. Chem. Soc.

1989, 111, 7–15.

138. Jug, K.; Koester, A. M. “Aromaticity as a multi-dimensional phenomenon,” J. Phys.

Org. Chem. 1991, 4, 163–169.

139. Schleyer, P. v. R.; Freeman, P. K.; Jiao, H.; Goldfuss, B. “Aromaticity and antiaromaticity in five-membered C4H4X ring systems: classical and magnetic concepts may

not be orthogonal,” Angew. Chem. Int. Ed. Engl. 1995, 34, 337–340.

140. Katritzky, A. R.; Karelson, M.; Sild, S.; Krygowski, T. M.; Jug, K. “Aromaticity as a

quantitative concept. 7. Aromaticity reaffirmed as a multidimensional characteristic,”

J. Org. Chem. 1998, 63, 5228–5231.

141. Cyranski, M. K.; Krygowski, T. M.; Katritzky, A. R.; Schleyer, P. v. R. “To what extent

can aromaticity be defined uniquely?,” J. Org. Chem. 2002, 67, 1333–1338.

142. Moran, D.; Simmonett, A. C.; Leach, F. E.; Allen, W. D.; Schleyer, P. v. R.; Schaefer,

H. F. III, “Popular theoretical methods predict benzene and arenes to be nonplanar,”

J. Am. Chem. Soc. 2006, 128, 9342–9343.

143. Baldridge, K. K.; Siegel, J. S. “Stabilization of benzene versus oligoacetylenes: not

another scale for aromaticity,” J. Phys. Org. Chem. 2004, 17, 740–742.

144. Roberts, J. D.; Streitwieser, A. J.; Regan, C. M. “Small-ring compounds. X. Molecular

orbital calculations of properties of some small-ring hydrocarbons and free radicals,”

J. Am. Chem. Soc. 1952, 74, 4579–4582.

145. Schaad, L. J.; Hess, B. A., Jr. “Dewar resonance energy,” Chem. Rev. 2001, 101,

1465–1476.

146. Pauling, L. The Nature of the Chemical Bond; Cornell University Press: Ithaca, NY,

1960.

147. Wheland, G. W. The Theory of Resonance; John Wiley: New York, 1944.

148. Mo, Y.; Schleyer, P. v. R. “An energetic measure of aromaticity and antiaromaticity

based on the pauling-wheland resonance energies,” Chem. Eur. J. 2006, 12,

2009–2020.

149. Dewar, M. J. S.; De Llano, C. “Ground states of conjugated molecules. XI. Improved

treatment of hydrocarbons,” J. Am. Chem. Soc. 1969, 91, 789–795.



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