Conjugated Carbon Centered Radicals, High-Spin System and Carbenes

462 Pages·2002·3.041 MB·English

by  H. Fischer (auth.), H. Fischer (eds.)

General introduction 1
I General introduction
H. Fischer
A Definition and substances
In the context of these tables the term free radical means a chemically stable or transient paramagnetic
atomic or molecular species which derives its paramagnetism from a single, unpaired valence shell
electron. Following this definition the tables cover
a) atoms and atomic ions in ground and excited 2S and 2P states,
b) diatomic and linear polyatomic molecules in 2Σ and 2Π states,
c) polyatomic molecules and molecular ions which arise or may be thought to arise from the break of a
single bond of a diamagnetic molecule or molecular ion,
d) mono-(tri-, penta-, etc.) - negative or - positive ions of neutral organic or inorganic compounds.
Not classified as free radicals are atoms or molecules in ground or excited electronic states with
multiplicities larger than two (e.g. O, 3P; O , 3Σ; N, 4S; molecules in excited triplet states), transition
2
metal ions and their complexes deriving their paramagnetism exclusively or mainly from d- and f-
electrons and charge transfer complexes. However, a number of polyatomic molecular species which do
not fulfill the above definition are included because their properties closely resemble those of structurally
closely related free radicals. These are
e) metal(0) complexes and clusters,
f) high spin polyradicals with electron exchange or dipolar couplings not greatly exceeding the Zeeman
or hyperline interactions, triplet carbenes and poly-carbenes,
g) selected transition metal complexes deriving their paramagnetism from free radical ligands and the
electrons of the center atom.
The volumes cover only compounds with unambiguously verified or at least very plausibly assumed
structures. Papers which only state the presence of free radicals in a sample and do not give detailed
structures nor magnetic properties are not reviewed. Also not covered are publications which deal
exclusively with other topics than experimental determinations of magnetic properties of free radicals.
Such work may however be mentioned in footnotes or as further references at the appropriate places.
The ordering of the substances into subclasses is given in the general table of contents. The ordering
within the subclasses is explained, where not self explanatory, in the introductions to the individual
chapters.
The literature was considered mainly for the period of 1985 to 2001. The earlier literature was covered
in: Magnetic Properties of Free Radicals, Landolt-Börnstein, New Series, Group II, Vol. 1. Berlin:
Springer 1965; Landolt-Börnstein, New Series, Group II, Vols. 9a-9d2. Berlin: Springer 1977-80;
Landolt-Börnstein, New Series, Group II, Vols. 17a-17h. Berlin: Springer 1986-90. Further information
on free radicals is also found in: Radical Reaction Rates in Liquids, Landolt-Börnstein, New Series,
Group II, Vols. 13a-13e. Berlin: Springer 1984-85; Landolt-Börnstein, New Series, Group II, Vols. 18a-
18e2. Berlin: Springer 1994-97.
B Magnetic properties
The magnetic properties of most free radicals can conveniently be represented by parameters describing
their interaction with an external magnetic field and the intra-molecular hyperfine interactions, i.e. the
parameters g and aλ of the Spin-Hamiltonian
H = µµµµB B0 g S - Σ µN gNλ B0 Iλ + Σ S aλ Iλ
λ λ

Landolt Börnstein
New Series II/26B
2 General introduction
where µµµµB, µN, B0, g, S, gNλ, aλ, Iλ are the Bohr magneton, the nuclear magneton, the magnetic induction,
the g-tensor of the radical, the electron spin operator, the nuclear g-factor of nucleus λ, the hyperfine
coupling tensor of nucleus λ, and the spin operator of nucleus λ, respectively.
g is symmetric and the mean value of its diagonal elements

3
Σ
g = 1/3 g
ii
i=1
is called the isotropic g-factor. For many radicals g deviates only slightly from the g-factor of the free
electron
g = 2.002319304386(20)
e
aλ, the hyperfine coupling tensor, describes the dipolar and contact interaction between the electron
spin momentum and the nuclear spin momentum of nucleus λ of the radical. aλ is most often also
symmetric and the mean value

3
Σ
aλ = 1/3 aii, λ
i=1
is called the isotropic hyperfine coupling constant or splitting parameter. If a radical contains several
nuclei which interact there are several tensors aλ. In general their principal axes do not coincide, nor do
they with the principal axes of g.
For polyatomic radicals in the gas phase the above Spin-Hamiltonian does not apply and four
magnetic hyperfine coupling constants a, b, c, d are needed to describe the interaction between a nuclear
and the electron spin. These are defined and explained in the introduction to the tables on inorganic
radicals.
Polyradicals and certain radicals on transition metal complexes have N unpaired electrons located on
different molecular segments k. Their Spin-Hamiltonian is
N N
H = µµµµB Σ B0 gk Sk + J Σ Sk Sl + S D S + Σ Σ Sk aλk Iλk
k l>k=1 k=1 λ
where the nuclear Zeeman terms are omitted and
S = Σ Sk .
k
J is the electron exchange parameter and D the zero-field splitting tensor. D is symmetric and
traceless, i.e.
3
Σ D = 0
ii
i=1
and consequently the two zero-field splitting parameters
D = 3/2 D
33
E = 1/2 (D - D )
11 22
Landolt Börnstein
New Series II/26B
General introduction 3
completely determine the tensor. J determines the energy separation of different spin states of the N-Spin
System. For N=2
J = E - E
triplet singlet
and for N=3
3/2 J = E - E .
quartet doublet
Further information on the description of N-electron spin systems are found in the introductions to the
appropriate chapters.
There are many experimental techniques in both continuous wave or pulse forms for the determination
of the Spin-Hamiltonian parameters g, aλ, J, D, E. Often applied are Electron Paramagnetic or Spin
Resonance (EPR, ESR), Electron Nuclear Double Resonance (ENDOR) or Triple Resonance, Electron-
Electron Double Resonance (ELDOR), Nuclear Magnetic Resonance (NMR), occasionally utilizing
effects of Chemically Induced Dynamic Nuclear or Electron Polarization (CIDNP, CIDEP), Optical
Detection of Magnetic Resonance (ODMR) or Microwave Optical Double Resonance (MODR), Laser
Magnetic Resonance (LMR), Atomic Beam Spectroscopy, and Muon Spin Rotation (µSR). The
extraction of data from the spectra varies with the methods, the systems studied and the physical state of
the sample (gas, liquid, unordered or ordered solid). For the detailed procedures the reader is referred to
the original literature and the monographs (D) listed below. Further, effective magnetic moments µ of
eff
free radicals are often known from static susceptibilities. In recent years such determinations are rare, but
they may be mentioned in the tables. A list of references covering the abundant earlier literature is found
in: Magnetic Properties of Free Radicals, Landolt-Börnstein, New Series, Group II, Vol. 1, Berlin:
Springer 1965, Vols. 9a-9d2, Berlin: Springer 1977-80 and Vols. 17a-h, Berlin: Springer 1986-90.
C Arrangements of the tables
For the display of the data the volumes are divided into chapters on specific classes of compounds. These
are prepared by authors who are experts in these fields. Each chapter is headed by an introduction which
specifies the coverage, the ordering of substances, details of the data arrangement, the special general
literature and special abbreviations, if necessary. The tables are followed by the references belonging to
the individual entries. A small overlap between chapters has been allowed for reasons of
comprehensiveness and consistency. An index of all substances appears at the end of the last subvolume
of the series.
Within the individual chapters the data are arranged in columns in a manner, which, as far as possible,
holds for all chapters:
The first column (Substance) describes the structure of the species. It contains the gross formula
including charge and, where appropriate, information on the electronic state. Whenever possible a
structural formula is also given or a reference to a structural formula displayed elsewhere.
The second column (Generation/Matrix or Solvent/Method/T[K]) briefly describes the method of
generation of the species, the matrix or solvent in which it was studied, the experimental technique
applied to obtain the magnetic properties and the temperature for which the data are valid in Kelvin. 300
normally means an unspecified room temperature.
The third column contains the magnetic properties. For radicals it is headed g-Factor, a-Value[mT],
and the information on g is given first where available. If only one value is listed it is the isotropic g-
factor. If four values are listed the first three are the principal elements of g, the fourth denoted by is: is
the mean value. For axially symmetric g occasionally only the two principal elements and the isotropic g
are listed. These entries are followed by the information on the hyperfine interactions. It states the nuclei
by their chemical symbols, a left upper index denoting the isotope, if necessary. Numbers preceding the
chemical symbols note the number of equivalent nuclei, i.e. 3H means three equivalent 1H nuclei. Right
hand indices of the symbols or information given in parentheses point to positions of the nuclei in the
structural formulae. The a-values are displayed following the symbols. If only one value is given it is the
Landolt Börnstein
New Series II/26B
4 General introduction
isotropic part of the coupling tensor. If four values are listed the first three are the principal values of a,
the fourth denoted by is: is the isotropic part. Signs are given if they are known. Errors are quoted in
parentheses after the values in units of the last digit quoted for the value.
In the tables on high spin systems the third column also gives the available information on the
exchange and zero-field parameters J, D and E, and the heading is changed accordingly. Further, in some
tables where liquid-crystal data are reported column five may give besides the isotropic coupling constant
a the shift ∆a caused by the partial alignment. It is related to the elements of a by
∆a = 2/3 Σ O a
ij ji
i, j
where O are the elements of the traceless ordering matrix. For the extraction of the parameters from the
ij
spectra the original literature and the introduction to the individual chapters should be consulted. Finally,
for radicals observed in the gas phase the third column lists the hyperfine coupling constants a, b, c, d.
The general unit of a-values in column three is milli-Tesla [mT] with the occasional and well founded
exception of Mc/s (MHz) for a few cases. The original literature often quotes coupling constants in Gauss
and the conversion is
1 mT = 10 Gauss = 28.0247 (g/g) Mc/s .
e
For the interaction energy terms J, D and E the unit cm-1 is used with 1 cm-1 = c -1 · 1 c/s where c is the
0 0
vacuum light velocity.
The fourth column (Ref./Add. Ref.) lists the reference from which the data of the former columns are
taken. This reference may be followed by additional but secondary references to the same subject. All
references belonging to one chapter are collected in a bibliography at the end of this chapter, and the
respective pages are referred to at the top of each page.
Throughout the chapters footnotes give additional information or explanations. A list of general
symbols and abbreviations are found at the end of each subvolume and the last subvolume contains an
index.
D Monographs, reviews and important conference proceedings
Atkins, P. W., Symons, M. C. R.: The Structure of Inorganic Radicals. Amsterdam: Elsevier 1967.
Ayscough, P. B.: Electron Spin Resonance in Chemistry. London: Methuen 1967.
Carrington, A., McLauchlan, A. D.: Introduction to Magnetic Resonance. Harper International 1967.
Gerson, F.: Hochauflösende ESR-Spektroskopie. Weinheim: Verlag Chemie 1967.
Poole, C. P., Jr.: Electron Spin Resonance. New York: Interscience 1967.
Alger, R. S.: Electron Paramagnetic Resonance. New York: Interscience 1968.
Kaiser, E.T., Kevan, L.: Radical Ions. New York: Interscience 1968.
Scheffler, K.. Stegmann, H. B.: Elektronenspinresonanz. Berlin, Heidelberg, New York: Springer 1970.
Geschwind. S., (Editor): Electron Paramagnetic Resonance. New York: Plenum Press 1972.
McLauchlan, K. A.: Magnetic Resonance. Oxford: Clarenden Press 1972.
Muus, L. T., Atkins. P. W., (Editors): Electron Spin Relaxation in Liquids. New York: Plenum Press
1972.
Swartz, H. M.. Bolton. J. R., Borg. D.C.: Biological Applications of Electron Spin Resonance. New York:
Wiley 1972.
Wertz, J. E., Bolton, J. R.: Electron Spin Resonance. New York: McGraw-Hill 1972.
Atherton, N. M.: Electron Spin Resonance, Theory and Applications. New York: Halsted 1973.
Buchachenko, A. L., Wassermann. A. L.: Stable Radicals. Weinheim: Verlag Chemie 1973.
Kochi, J. K.. (Editor): Free Radicals. New York: Wiley 1973.
Norman, R. O. C., Ayscough, P. B., Atherton, N. M., Davies, M. J., Gilbert, B. C., (Editors): Electron
Spin Resonance. Specialist Periodical Reports. London: The Chemical Society 1973ff.
Landolt Börnstein
New Series II/26B
General introduction 5
Pake, G. E., Estle, T. L.: The Physical Principles of Paramagnetic Resonance, 2nd Ed.. Reading: Benjamin
1973.
Carrington, A.: Microwave Spectroscopy of Free Radicals. London: Academic Press 1974.
Box, H.C.: Radiation Effects. ESR and ENDOR Analysis. New York: Academic Press 1977.
Muus, L. T., Atkins. P. W., McLauchlan. K. A., Pedersen, J. B., (Editors): Chemically Induced Magnetic
Polarization, Dordrecht: Reidel 1977.
Ranby, B., Rabek. J. F.: ESR Spectroscopy in Polymer Research. Berlin: Springer 1977.
Harriman, J. E.: Theoretical Foundations of Electron Spin Resonance. New York: Academic Press 1978.
Slichter, C. P.: Principles of Magnetic Resonance. Berlin: Springer 1978.
Symons, M. C. R.: Chemical and Biochemical Aspects of Electron Spin Resonance Spectroscopy. New
York: van Nostrand-Reinhold 1978:
Dorio, M. M.. Freed. J. H., (Editors): Multiple Electron Resonance Spectroscopy. New York: Plenum
Press 1979.
Kevan, L., Schwartz. R.: Time Domain Electron Spin Resonance. New York: Wiley 1979.
Shulman, R. G., (Editor): Biological Applications of Magnetic Resonance, New York: Academic Press
1979.
Bertini, I., Drago, R. S.: ESR and NMR of Paramagnetic Species in Biological and Related Systems.
Hingham: Kluver Boston 1980.
Gordy, W.: Theory and Applications of Electron Spin Resonance. New York: Wiley 1980.
Il’yasov, A. V., Kargin, Yu. M., Morozova, I. D.: EPR Spectra of Organic Radical Ions. Moscow: Nauka
1980.
Molin, Yu. N., Salikhov, K. M., Zamaraev, K. I.: Spin-Exchange – Principles and Applications in
Chemistry and Biology. Berlin: Springer-Verlag 1980.
Schweiger, A.: Structure and Bonding, Vol. 51: Transition Metal Complexes: Electron Nuclear Double
Resonance of Transition Metal Complexes with Organic Ligands. Berlin: Springer-Verlag 1982.
Carrington, A., Hudson. A., McLauchlan, A. D.: Introduction to Magnetic Resonance, 2nd ed. New York:
Chapman and Hall, 1983.
Poole, C. P.: Electron Spin Resonance, 2nd ed. New York: Wiley 1983.
Walker, D.C.: Muon and Muonium Chemistry. Cambridge: Cambridge University Press 1983.
Weltner, W., Jr.: Magnetic Atoms and Molecules. New York: van Nostrand-Reinhold 1983.
Kokorin, A. I., Parmon, V. N., Shubin, A. A.: Atlas of Anisotropic EPR Spectra of Nitric Oxide
Biradicals. Moscow: Nauka 1984.
Salikhov, K.M.. Molin, Yu. N., Sagdeev, R. Z., Buchachenko, A. L.: Spin Polarization and Magnetic
Effects in Radical Reactions. Amsterdam: Elsevier 1984.
Dalton, L. R., (Editor): EPR and Advanced EPR Studies of Biological Systems. Boca Raton: CRC Press
1985.
Il’yasov, A. V., Morozova, I. D., Vafina, A. A., Zuev, M. B.: EPR Spectra and Stereochemistry of
Phosphorous-Containing Free Radicals. Moscow: Nauka 1985.
Kirmse, R., Stach, J.: ESR-Spectroskopie. Anwendungen in der Chemie. Berlin: Akademie-Verlag 1985.
Wertz, J. E., Bolton, J. R.: Electron Spin Resonance: Elementary Theory and Practical Applications. New
York: Chapman and Hall 1986.
Kurreck, H., Kirste, B., Lubitz, W.: Electron Nuclear Double Resonance Spectroscopy of Radicals in
Solution. Weinheim: VCH Verlagsgesellschaft 1988.
Roduner, E.: The Positive Muon as Probe in Free Radical Chemistry. Berlin: Springer-Verlag 1988.
Waugh, J. S., (Editor): Advances in Magnetic Resonance, Vol. 12. San Diego: Academic Press 1988.
Hoff, A. J., (Editor): Advanced EPR. Applications in Biology and Biochemistry. Amsterdam: Elsevier
1989.
Platz, M. S., (Editor): Kinetics and Spectroscopy of Carbenes and Biradicals. New York: Plenum 1990.
I’Haya, Y. J., (Editor): Spin Chemistry. Tokyo: The Oji International Conference on Spin Chemistry
1991.
Bagguley, D. M. S., (Editor): Pulsed Magnetic Resonance: NMR, ESR and Optics, a Recognition of E. L.
Hahn. Oxford: Oxford University Press 1992.
Weil, J. A., Bolton, J. R., Wertz, J. E.: Electron Paramagnetic Resonance: Elementary Theory and
Practical Applications. New York: Wiley 1994.
Landolt Börnstein
New Series II/26B
6 General introduction
Lowe, D. J., (Editor): ENDOR and EPR of Metalloproteins. Berlin: Springer-Verlag 1995.
Sutcliffe, L. H., (Editor): Electron Spin Resonance, the Fiftieth Anniversary of Zavoiski’s Discovery of
Electron Resonance Spectroscopy (in Magn. Reson. Chem, 1995, 33, Spec. Issue). Chichester: Wiley
1995.
Brey, W. S., (Editor): Magnetic Resonance in Perspective: Highlights of a Quarter Century. San Diego:
Academic Press 1996.
Henry, Y., Guissani, A., Ducastel, B., (Editors): Nitric Oxide Research from Chemistry to Biology: EPR
Spectroscopy of Nitrosylated Compounds. Berlin : Springer-Verlag 1996.
Salikhov, K. M., (Editor): Magnetic Isotope Effect in Radical Reactions. Vienna, Springer-Verlag 1996.
Eaton, G. S., Eaton, S. S., Salikhov, K. M., (Editors): Foundations of Modern EPR. Singapore: World
Scientific Publ. Co. 1998.
Nagakura, S., Hayashi, H.; Azumi, T., (Editors): Dynamic Spin Chemistry. Tokyo: Kodansha Ltd. 1998.
Poole, C. P.: Handbook of Electron Spin Resonance, Volume 2. Secausus: AIP 1999.
Berliner, L. J., Eaton, G. R., Eaton, S. S., (Editors): Distance Measurements in Biological Systems by
EPR. New York: Plenum 2000.
Schweiger, A., Jeschke, G.: Principles of Pulse Electron Paramagnetic Resonance Spectroscopy. Oxford:
Oxford University Press 2001.
Landolt Börnstein
New Series II/26B
Ref. p. 303] 5 Carbon radicals with conjugated π-systems 7
ππππ
5 Carbon radicals with conjugated -systems
F. A. Neugebauer
5.1 Introduction
5.1.1 General remarks
In continuation of chapter 4 in Landolt-Börnstein, New Series, Vol. II/17c, the literature has been
surveyed beginning with the year 1986 (except the references published in Vol. II/17c) and ending in
2000. Data of the year 2000 may be not complete. The given earlier references (1978–1985) refer mainly
to µSR data which have not been considered previously. Main sources for references have been
“Chemical Abstracts“, the specialist periodical reports: “Electron Spin Resonance“ (The Royal Society of
Chemistry, London), and the bibliographies of the surveyed references.
The carbon radicals with conjugated π-systems in this chapter are defined as species which , in terms of
valence bond nomenclature, can be represented by at least two resonance structures locating the unpaired
electron on two or more carbons.
− −
Ketyl and thioketyl radicals are included as O - or S -substituted derivatives of corresponding carbon
radicals with conjugated π-systems after the corresponding OH- or SH-substituted radicals.
Radicals containing heteroatoms (e.g. N, O) as π-centers are included when, in terms of valence bond
resonance structures, the unpaired electron is not located at the heteroatom (e.g. 2-azaallyl, 2-oxaallyl).
Transverse field muon spin rotation (FT-µSR) has enabled the study of a wide range of organic
radicals, formed by addition of the light hydrogen isotope muonium (Mu ≡ µ+e−) to unsaturated
molecules during irradiation with positive muons (µ+). Muon-electron hyperfine coupling constants are
related to the radical structures in the same way as corresponding hydrogen-electron couplings of
analogous H-substituted radicals. Reduction of a(Mu) by the muon/proton relative magnetic moments,
µµ/µp = 3.1833, gives a(Mu)⋅µp/µµ values [in the tables Mu(µp/µµ)], which can be compared with a(H)
data of hydrogens in equivalent positions. Furthermore, avoided-level-crossing muon spin resonance
(ALC-µSR) allows the determination of other nuclear hyperfine coupling constants, e.g. a(H), a(D),
a(13C), a(F).
5.1.2 Arrangement of tables
1. The first principle of ordering is the number of conjugated π-electrons of unsubstituted basic
radicals:
3π-electrons: allyl, cyclic allyl, allenyl
5π-electrons: pentadienyl, cyclic pentadienyl
7π-electrons: cyclic heptatrienyl, benzyl, and related radicals
9π-electrons: indenyl, dihydronaphthyl, benzopyridinyl, benzopyryl, benzothiapyryl
11π-electrons: naphthylmethyl and related radicals
13π-electrons: phenalenyl, diphenylmethyl, dibenzocyclohexadienyl, and related radicals
15π-electrons: diphenylvinylmethyl, dibenzoheptatrienyl, dihydropyrenyl
17π-electrons: 2-furyldiphenylmethyl, naphthylphenylmethyl
19π-electrons: tribenzocycloheptatrienyl, triphenylmethyl, and related radicals
Landolt-Börnstein
New Series II/26B
8 5.1 Introduction [Ref. p. 303
π-electrons of substituents (e.g. vinyl, phenyl, aryl groups) attached to these basic systems are not
counted (tetraphenyl allyl can be found under allyl radicals).
Exceptions:
Radicals of type 1 and type 2 are presented in connection with pyryl or thiapyryl (5π) radicals (3).
X [ ] X . [ ] X
. n n .
X X

X = O, S 1 2 3
Similarly, radicals of type 4 and type 5 are presented in connection with benzopyryl or benzothiapyryl
(9π) radicals (6).
X [ ] X . [ ] X
. n n .
O O

X = O, S 4 5 6
7H-Benz[d,e]anthracen-7-yl radicals (e.g. 7), 7H-dibenz[a,kl]anthracen-7-yl (8), and 7H-benzo[d,e]-
naphthacen-7-yl (9) are treated together with dibenzocyclohexadienyl (13π) radicals (10).
_
O H H H
. . . .
7 8 9 10
The largest conjugated 45π-electron system 11, which consists of three phenalene subunits attached to a
benzene center, is presented in connection with phenalenyl (13π) radicals (12).
.
.

11 12
2. Within the groups defined under 1. open chain radicals are followed by semicyclic, carbocyclic, and
heterocyclic systems. Only those systems are termed “cyclic“, in which different π-centers are connected
to a cycle. Radicals with partial structures like 13 and 14, where the same π-center is the beginning and
the end of a cycle are treated together with dialkyl substituted species.
Landolt-Börnstein
New Series II/26B
Ref. p. 303] 5 Carbon radicals with conjugated π-systems 9
. .
13 14

3. The following additional subdivisions have been introduced: radicals like
H H H R R R
. precede . precede .

. . .
H H R
C precede C precede C
H R R
4. Substituents. The radicals of equal basic structure are arranged within individual tables according to
the following ordering of substituents:
Substituent is hydrogen - substituent is bound to the basic structure by a carbon–carbon bond (leading
atom is carbon) - substituent is bound to the basic structure by a heteroatom–carbon bond (leading atom
is the heteroatom).
Carbon substituents are arranged in the order: primary alkyl, secondary alkyl, tertiary alkyl, vinyl, aryl,
cyano, acyl, acyloxy, etc. Substituents with leading heteroatom are ordered alphabetically to the chemical
symbol, i.e. Al, B, Br, Cl, Co, F, Ga, Ge, I, Mn, N, O, P, Pb, Re, S, Se, Si, Sn, Te. Radicals differing from
each other by varying substituents of substituents are ordered according to the same principle.
5. Numbering of positions is to be taken from the corresponding structural formula. Frequently, the
given numbering does not follow the systematic numbering of the precursor of the radical.
6. Stereochemical positions of substituents of allyl radicals are indicated by “endo“ and “exo“. Allyl
radicals with known stereochemistry are drawn in the bent form 15, those with unknown stereochemistry
linearly (16).
.
.
exo
15 RR' C C CR"R"' 16
endo
7. For some radicals the magnetic properties have been determined for different molecular
environments or temperatures. In these cases the display of the data follows the order: gas phase, solution
(with increasing polarity of the solvent), matrix, single crystal, polycrystalline. For the same environment
and different temperatures they are arranged according to increasing temperatures.
Landolt-Börnstein
New Series II/26B
10 5.2.1 Allyl and labeled allyl radicals [Ref. p. 303
Substance Generation / Matrix or g-Factor / Ref. /
Solvent / Method / T [K] a-Value [mT] add. Ref.
5.2 Radicals with 3 conjugated pppp-electrons
5.2.1 Allyl and labeled allyl radicals
[C H ] 2.8-MeV e-irr. of 2.00252 88McM1
3 5
propene 1)/
H 2H(1,3, exo): 1.483 88His1/
.
H H exo H O 2H(1,3, endo): 1.392 89Dai1/
1 2 3 2 H(2): 0.420 90Sch1/
H H endo
ESR / 290 91Suz1/
92But1/
97Per11)
2.8-MeV e-irr. of 2.00252
[1-13C]propene
2H(1,3, exo): 1.483
H O 2H(1,3, endo): 1.392
2
H(2): 0.420
ESR / 290 13C(1): 2.193
2.8-MeV e-irr. of 2.00253
[2-13C]propene
2H(1,3, exo): 1.487
H O 2H(1,3, endo): 1.397
2
H(2): 0.422
ESR / 290 13C(2): 1.721
1) Ab initio calculations.
[C H D ] Reaction of Al atoms H(1, exo): 1.48 88How1
3 3 2
with [1,1-D ]propene H(1, endo): 1.4
2
H (rotating cryostat) at H(2): 0.4
.
H D exo 77 K D(3, exo): 0.23
1 2 3 D(3, endo): 0.21
H D endo
Adamantane
ESR / 162
[C D ] Reaction of Al atoms 2D(1,3, exo): 0.23 88How1
3 5
with [D ]propene 2D(1,3, endo): 0.21
6
D (rotating cryostat) at D(2): 0.06
.
D D exo 77 K
1 2 3
D D endo
Adamantane
ESR / 255
Landolt-Börnstein
New Series II/26B