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Book Review Carbene Carbenoide und Carbenanaloge (Carbenes Carbenoids and Carbene Analogs). By W

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The reactions of methyl radicals with silane, disilane ,phenylsilane, and their Si-deuterated analogs, which proceed via
H or D abstraction, have been studied by 0. P. Sfruusz,
E. Jakubowski, H . S . Sandhu, and H. E. Gunning. The methyl
radicals were produced by photolysis of azomethane and the
product distributions determined by mass spectrometry and
gas chromatography. Silanes are more reactive than hydrocarbons; the activation energies of the reactions are lower,
while the pre-exponential factors are equal. The reactions
CH;+ CH4
=
CH4
+ CH;
(1)
and
CH;
+ SiH4 = SiH; + CH4
(2)
are compared as an example: the activation energies are 14.65
kcal mole-1 for eq. (1) and 6.99 kcal mole-1 for eq. (2); the
logarithms ofthepre-exponential factors are 11.83 cm3 mole-1
s-1 for eq. (1) and 11.80 cm3 mole-1 s-1 for eq. (2). / J. chem.
[Rd 102 IE]
Physics 51, 552 (1960) /-Hz.
Trimethyltin isothiocyanate is reported by R . A. Forder and
G. M. Sheldrick to consist of zig-zag chains containing linear
S . . . Sn-N-C-S
units arranged along the z axis of the
orthorhombic unit cell (a = 13.20, b = 10.28, c = 12.01, all
~ 0 . 0 1A; Z = 8; dcalc. = 1.82 g/cm3), the bond angle at the
S atom being 97 rt 2O. The C3Sn unit is almost planar with
d SnC = 2.13 f 0.03 A. Theinteratomic distances are S . . . Sn
3.13 f 0.02, SnN 2.15 f 0.06, NC 1.15 f 0.07, and CS
1.64 f 0.07 A; the bond lengths in the NCS group lie between
those in HN=C=S and CH3S-C = N and thus suggest resonance of the kind
=S
. . .Sn-N=C=S.. .Sn-N=
++
9
d
e
-S-Sn-N=C-S-Sn-NF
e
which requires no contributions from @+d), bonding to
explain the stereochemistry. / Chem. Commun. 1969, 1125 /
-HB.
[Rd 104 lE]
The IR spectrum of CO in zeolites has been subjected to
investigation by P. J. Fenelon and H . E. Rubalcuva. It can be
deduced from the differences between the spectra of pure
12C160 and a mixture of 12C160 and 13C16O that CO can
rotate relatively freely in the cavities of Na zeolites (diameter
of cavity in Na zeolite 11.4 A, effective diameter of the rotating CO molecule approx. 4.5 A). The spectrum corresponds
approximately to that of CO gas at 50 atm. In Ca zeolites,
where considerably stronger adsorption forces occur, the
spectrum resembles that of liquid CO. It can be interpreted if
a relatively high threshold potential is assumed for the rotation. / J. chem. Physics 51, 961 (1969) / -Hz.
[Rd 107 JE]
The conductivity of aqueous electrolyte solutions in shock
waves has been studied by S. D . Hamann and M . Linton.
The molar conductivity of KCl does not change significantly
in shock waves up to 140 kbar; although the temperature
jump should increase the mobility of K+ and C1-, this effect
is cancelled by the simultaneous increase in the density. On
the other hand, the conductivities of KOH and HCI are increased several-fold, signifying that the additional mobilities
of H30f and OH- increase by a factor of 3 to 4 under shockwave conditions. The ionic product of water is estimated as
0.09 x 10-6 mole2 g-2 at a shock-wave pressure of 133 kbar.
A careful extrapolation permits the assumption that water is
almost completely dissociated at 200 kbar and then possesses
properties similar to a fused salt. A discontinuity in the compressibility curve of water in the region around 15&200 kbar
lends further support to such a concept. / Trans. Faraday
SOC.65, 2186 (1969) / -HZ.
[Rd 108 IE]
BOOK REVIEWS
Carbene, Carbenoide und Carbenanaloge (Carbenes, Carbenoids, and Carbene Analogs). By W . Kirmse. Vol. 7 of
“Chemische Taschenbiicher”. edited by W. Foerst and
H. Grcnewuld. Verlag Chemie GmbH., Weinheim/Berastr.
1969. 1st Edit., 260 pp.. 4 figs., 26 tables, paperback D M
18.-.
One of the focal points of organic chemical research during
the past decade has been the detection of short-lived intermediates and this has simultaneously given a new impulse to
preparative work. This intimate mixture of theory and practice is illustrated in Kirmse’s book on Carbenes, Carbenoids,
and Carbene Analogs. The author is an expert and successful
research worker in the outlined field and has mastered his
task in the concise style required by a pocket book.
He begins with an introduction to the theory of particles
containing bivalent carbon, passes to their reactivity in the
gas phase (where carbenes have been demonstrated beyond
dispute), and then turns to their reactions in solution. Here
there is a high probability that occurrence of carbenes must
be taken into account, so far as they are produced by photolysis or thermolysis of diazo compounds. Their characteristic
reactions are set out briefly and clearly with a large number
of examples.
The critical basis for the probability of production of carbenes or carbenoids is also presented. This is important for
the evaluation of reaction mechanisms with carbenoids
prepared by different methods, particularly those which are
organometallic. The next chapter concerning intramolecular
reactions introduces the reader to the role of carbenes and
Angew. Chem. internat. Edit.
VoI. 8 (1969) / No. I1
carbenoids in synthetic planning, to the extent that one
recognizes that they permit access to unusual ring structures
which are otherwise scarcely obtainable. - In the preparative
section, the synthesis of cyclopropane derivatives is given
prominence. These structures are able, in turn, to give
interesting transformations, either during the process of
formation or thereafter. The final chapter deals with carbene
analogs. Fascinating studies are described here concerning
the reactivity of carbon in the vapor phase and of the nitrenes.
The chemistry of these species corresponds in many respects
to that of carbenes.
The art of omission, which will not please everyone, is here
well warrented. The essential points (literature up to 1968
inclusive) have been clearly brought out by the author. Apart
from some misprints, the book can be warmly recommended
to all scientists, particularly to organic and organometallic
chemists.
G . Wittig [NB 827 IE]
Organometallic Chemistry. By P . L. Puuson. Edward Arnold
(Publishers) Ltd. Maidenhead 1967. 1st Edit., 202 pp.,
stitched ~ O S . bound
,
50s.
According to the author, who is Freeland Professor of Chemistry at the University of Strathclyde, Glasgow, this book is
intended, not for specialists, but as a general introduction for
advanced students.
A general, very concise introductory section on structure,
bonding, and thermochemical data is followed by skillfully
931
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