Page 13 of 15
Journal of the American Chemical Society
(3) Hoffmann, R. Trimethylene and the addition of methylene to
ethylene. J. Am. Chem. Soc. 1968, 90, 1475–1485.
(4) Salem, L.; Rowland, C. The Electronic Properties of Diradicals.
Angew. Chem., Int. Ed. Engl. 1972, 11, 92–111.
(5) Borden, W. T. In Diradicals; Borden, W. T., Eds.; Wiley-
Interscience: New York, 1982; pp 1.
(6) (a) Abe, M. Diradicals. Chem. Rev. 2013, 113, 7011–7088.
(b)McClelland, R. A. In Reactive Intermediate Chemistry; Moss, R. A.,
Platz, M. S., Jones Jr. M., Eds; Wiley & Sons: Hoboken, New Jersey,
2004; pp 3–40.
(7) (a) Amyes, T. L.; Toteva, M. M.; Richard, J. P. In Reactive
Intermediate Chemistry; Moss, R. A., Platz, M. S., Jones Jr. M., Eds;
Wiley & Sons: Hoboken, New Jersey, 2004; pp 41–68. (b) Gronert, S.
In Reactive Intermediate Chemistry; Moss, R. A., Platz, M. S., Jones Jr.
M., Eds; Wiley & Sons: Hoboken, New Jersey, 2004; pp 69–120.
(8) (a) Mayr, H.; Patz, M. Scales of Nucleophilicity and
Photodenitrogenation
Stereoselectivity
of
2,3-
Diazabicyclo[2.2.1]heptanes. J. Phys. Chem. B, 2016, 120, 7217–7226.
(22) Abe, M.; Adam, W.; Hara, M.; Hattori, M.; Majima, T.; Nojima,
M.; Tachibana, K.; Tojo, S. On the Electronic Character of Localized
Singlet 2,2-Dimethoxycyclopentane-1,3-diyl Diradicals:ꢀ Substituent
Effects on the Lifetime. J. Am. Chem. Soc. 2002, 124, 6540–6541.
(23) Abe, M.; Hattori, M.; Takegami, A.; Masuyama, A.; Hayashi,
T.; Seki, S.; Tagawa, S. Experimental Probe for Hyperconjugative
Resonance Contribution in Stabilizing the Singlet State of 2,2-
Dialkoxy-1,3-diyls:ꢀ Regioselective 1,2-Oxygen Migration. J. Am.
Chem. Soc. 2006, 128, 8008–8014.
1
2
3
4
5
6
7
8
9
(24) Creary, X. Super Radical Stabilizers. Acc. Chem. Res. 2006, 39,
761–771.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
(25) Alabugin, I. V.; Gomes, G. dos. P.; Abdo, M. A.
Hyperconjugation. WIREs Comput Mol Sci. 2018, e1389.
(26) Nakagaki, T.; Sakai, T.; Mizuta, T.; Fujiwara, Y.; Abe, M.
Kinetic Stabilization and Reactivity of π Single‐Bonded Species: Effect
of the Alkoxy Group on the Lifetime of Singlet
2,2‐Dialkoxy‐1,3‐diphenyloctahydropentalene‐1,3‐diyls. Chem. Eur. J.
2013, 19, 10395–10404.
(27) Ye, J.; Fujiwara, Y.; Abe, M. Substituent effect on the energy
barrier for σ-bond formation from π-single-bonded species, singlet 2,2-
dialkoxycyclopentane-1,3-diyls. Beilstein. J. Org. Chem. 2013, 9, 925–
933.
(28) Abe, M.; Furunaga, H.; Ma, D.; Gagliardi, L.; Bodwll, G. J.
Stretch Effects Induced by Molecular Strain on Weakening σ-Bonds:
Molecular Design of Long-Lived Diradicals (Biradicals). J. Org. Chem.
2012, 77, 7612–7619.
(29) Harada, Y.; Wang, Z.; Kumashiro, S.; Hatano, S.; Abe, M.
Extremely Long Lived Localized Singlet Diradicals in a Macrocyclic
Structure: A Case Study on the Stretch Effect. Chem. Eur. J. 2018, 24,
14808–14815.
(30) (a) Kamada, K.; Ohta, K.; Kubo, T.; Shimizu, A.; Morita, Y.;
Nakasuji, K.; Kishi, R.; Ohta, S.; Furukawa, S.; Takahashi, H.; Nakano,
M. Strong Two-Photon Absorption of Singlet Diradical Hydrocarbons.
Angew. Chem., Int. Ed. 2007, 46, 3544–3546. (b) Kishi, R.; Murata, Y.;
Saito, M.; Morita, K.; Abe, M.; Nakano, M. Theoretical study on
diradical characters and nonlinear optical properties of 1, 3-diradical
compounds. J. Phys. Chem. A, 2014, 118, 10837–10848.
(31) (a) Nakano, M. Excitation Energies and Properties of Open-Shell
Singlet Molecules, Springer, 2014. (b) Sun, Z.; Zeng, Z.; Wu, J. Acc.
Chem. Res. 2014, 47, 2582. (c) Zeng, Z.; Shi, X.; Chi, C.; López
Navarrete, J. T.; Casado, J.; Wu, J. Chem. Soc. Rev. 2015, 44, 6578. (d)
Kubo, T. Chem. Lett., 2015, 44, 111. (e) Michl, J. Chem. Rev. 2010, 110,
6891–6936. (f) Hansmann, M. M.; Melaimi, M.; Munz, D.; Bertrand, G.
J. Am. Chem. Soc. 2018, 140, 2546–2554. (g) Dressler, J. J.; Teraoka,
M.; Espejo, G. L.; Kishi, R.; Takamuku, S.; Gómez-Garcia, C. J.;
Zakharov, L. N.; Nakano, M.; Casado, J.; Haley, M. M. Nature Chem.
2018, 10, 1134–1140.
Electrophilicity
: A System for Ordering Polar Organic and
Organometallic Reactions. Angew. Chem., Int. Ed. Engl. 1994, 33,
938−957. (b) For a comprehensive database of nucleophilicity
parameters N and sN as well as electrophilicity parameters E, see:
(9) (a) Hoffmann, R. Trimethylene and the Addition of Methylene to
Ethylene. J. Am. Chem. Soc. 1968, 90, 1475–1485. (b) Hoffmann, R.
Interaction of Orbitals Through Space and Through Bonds. Acc. Chem.
Res. 1971, 4, 1–9. (c) Getty, S. J.; Hrovat, D. A.; Borden, W. T. Ab Initio
Calculations on the Stereomutation of 1,1-Difluorocyclopropane.
Prediction of a Substantial Preference for Coupled Disrotation of the
Methylene Groups. J. Am. Chem. Soc. 1994, 116, 1521–1527.
(10) Adam, W.; Fragale, G.; Klapstein, D.; Nau, W. M.; Wirz, J.
Phosphorescence and Transient Absorption of Azoalkane Triplet States.
J. Am. Chem. Soc. 1995, 117, 12578–12592.
(11) Kita, F.; Adam, W.; Jordan, P.; Nau, W. M.; Wirz, J. 1,3-
Cyclopentanediyl Diradicals:ꢀ Substituent and Temperature
Dependence of Triplet−Singlet Intersystem Crossing. J. Am. Chem. Soc.
1999, 121, 9265–9275.
(12) Lineberger, W. C.; Borden, W. T. The synergy between
qualitative theory, quantitative calculations, and direct experiments in
understanding, calculating, and measuring the energy differences
between the lowest singlet and triplet states of organic diradicals . Phys.
Chem. Chem. Phys. 2011, 13, 11792–11813.
(13) Abe, M.; Ishihara, C.; Nojima, M. DFT Prediction of Ground-
State Spin Multiplicity of Cyclobutane-1,3-diyls:ꢀ Notable Effects of
Two Sets of Through-Bond Interactions. J. Org. Chem. 2003, 68, 1618–
1621.
(14) Abe, M.; Kawanami, S.; Ishihara, C.; Nojima, M. 2-Silyl Group
Effect on the Reactivity of Cyclopentane-1,3-diyls. Intramolecular
Ring-Closure versus Silyl Migration. J. Org. Chem. 2004, 69, 5622–
5626.
(15) Abe, M.; Je, J.; Mishima, M. The chemistry of localized singlet
1,3-diradicals (biradicals): from putative intermediates to persistent
species and unusual molecules with a π-single bonded character. Chem.
Soc. Rev. 2012, 41, 3808–3820.
(16) Abe, M.; Akisaka, R. Is π-Single Bonding (C–π–C) Possible? A
Challenge in Organic Chemistry. Chem. Lett. 2017, 46, 1586–1592.
(17) Ishihara, C.; Abe, M. Notable Substituent Effects on the Rate
Constant of Thermal Denitrogenation of Cyclic Azoalkanes: Strong
Evidence for a Stepwise Denitrogenation Mechanism. Aust. J. Chem.
2010, 63, 1615–1618.
(32) Niecke, E.; Fuchs, A.; Baumeister, F.; Nieger, M.; Schoeller, W.
W. A P2C2 Four‐Membered Ring with Unusual Bonding—Synthesis,
Structure, and Ring Opening of a 1,3‐Diphosphacyclobutane‐2,4‐diyl.
Angew. Chem., Int. Ed. 1995, 34, 555–557.
(33) Sugiyama, H.; Ito, S.; Yoshifuji, M. Synthesis of
1,3‐Diphosphacyclobutane‐2,4‐diyl from Mes*C ≡P. Angew. Chem.,
Int. Ed. 2003, 42, 3802–3804.
(34) (a) Ito, S.; Ueda, Y.; Hgot, T. T. T.; Kobayashi, M.; Hashizume,
D.; Nishida, J.-I.; Yamashita, Y.; Mikami, K. Direct Arylations for
Study of the Air-Stable P-Heterocyclic Biradical: From Wide Electronic
Tuning to Characterization of the Localized Radicalic Electrons. J. Am.
Chem. Soc. 2013, 135, 17610–17616. (b) Ito, S.; Ueta, Y.; Koshino, K.;
Kojima, K. M.; Mckenzie, I.; Mikami, K. Observation of a Metastable
a
(18) Abe, M.; Adam, W.; Nau, W. M. Photochemical Generation and
Methanol Trapping of Localized 1,3 and 1,4 Singlet Diradicals Derived
from a Spiroepoxy-Substituted Cyclopentane-1,3-diyl. J. Am. Chem.
Soc. 1998, 120, 11304–11310.
(19) Abe, M.; Adam, W.; Heidenfelder, T.; Nau, W. M.; Zhang, X.
Intramolecular and Intermolecular Reactivity of Localized Singlet
P‐Heterocyclic
Radical
by
Muonium
Addition
to
a
1,3‐Diphosphacyclobutane‐2,4‐diyl. Angew. Chem., Int. Ed. 2018, 57,
8608–8613.
Diradicals:ꢀThe
Exceedingly
Long-Lived
2,2-Diethoxy-1,3-
diphenylcyclopentane-1,3-diyl. J. Am. Chem. Soc. 2000, 122, 2019–
2026.
(35) (a) Schoeller, W. W.; Rozhenko, A.; Bourissou, D.; Bertrand, G.
On the Electronic Structures of the 1,3‐Diboracyclobutane‐1,3‐diyls and
Their Valence Isomers with a B2E2 Skeleton (E=N, P, As). Chem. Eur.
J. 2003, 9, 3611–3617. (b) Soleilhavoup, M.; Bertrand, G. Let’s Play
with Valence Isomers: The Influence of Different Main Group Elements
on Their Relative Stability. Bull. Chem. Soc. Jpn. 2007, 80, 1241–1252.
(20) Ye, J.; Hatano, S.; Abe, M.; Kishi, R.; Murata, Y.; Nakano, M.;
Adam, W. A Puckered Singlet Cyclopentane‐1,3‐diyl: Detection of the
Third Isomer in Homolysis. Chem. Eur. J. 2016, 22, 2299–2306.
(21) Abe, M.; Tada, S.; Mizuno, T.; Yamasaki, K. Impact of Diradical
Spin State (Singlet vs Triplet) and Structure (Puckered vs Planar) on the
13
ACS Paragon Plus Environment