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Crystal Structure of 4-Thiouridine.

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mine its structure with a view to contributing t o the solution
of this problem.
Fig. 3. Effect of pressure on the equilibrium (2) in methylarnine-arnmonia (2:l) at -120°C. The electron signal appears superimposed o n
the ESR septet of the benzene radical anions.
At this stage a number of structural peculiarities become
clear (see Fig. 1):
According t o the equation
Compound ( I ) could be obtained in the form of yellow prismatic crystals by slow evaporation of its aqueous solution.
Weissenberg photographs and diffractometer measurements
showed the space group to be C 2 and the dimensions of the
unit cell to be u = 13.174, b = 7.492, c = 13.042 A, /3 = 98.10 ’.
1400 reflections were recorded with an automatic diffractometer and corrected for geometrical factors but not for absorption. The structure analysis was performed by the heavy
atom technique. The usual Patterson and Fourier syntheses
and five cycles of isotropic and anisotropic refinement resulted in an R factor of 0.10.
the displacement of the equilibria (1) and (2), as determined
from the spectra, results in a volume change associated with
the reaction A V (= molar volume of the products minus
molar volume of the reactants) of -63 and -71 f 5 ml/mole,
respectively, reflecting the large apparent volume of the
electrons dissolved in the amine system.
For comparison, the equilibrium (2) was studied in tetrahydrofuran-dimethoxyethane (2:l; ether system), in which
only the benzene radical anions give rise to an ESR spectrum.
The intensity of the C6H6- spectrum, produced in the sample
cell by reaction of a benzene-ether solution at the surface of a
sodium wire, is independent of pressure in the region of 100
t o 400 atm at -100 ‘C. This result indicates that the apparent
volume of the diamagnetic electron species in the ether
system is smaller than that of the electrons dissolved in the
amine system.
// 146
Received: October 31, 1968
[Z 917 IEI
German version: Angew. Chern. 81, 118 (1969)
[*] Dr. K. W. Boddeker, Dip1.-Phys. G. Lang, and
Prof. Dr. U. Schindewolf
Institut fur Kernverfahrenstechnik der Universitrit
und des Kernforschungszentrurns
75 Karlsruhe, Postfach 3640 (Germany)
[l] U. Schindewov, K. W. Boddeker, and R . Vogelsgesang, Ber.
Bunsenges. physik. Chem. 70, 1161 (1966); U . Schindewolf and
R. Vogelsgesang, Angew. Chem. 79, 585 (1967); Angew. Chem.
internat. Edit. 6, 575 (1967); G . Lang, Diplomarbeit, Universitat
(TH) Karlsruhe, 1967; U . Schindewor, Angew. Chem. 80, 165
(1968); Angew. Chem. internat. Edit. 7, 190 (1968).
[21 E. J. Kirschke and W. L. Jolly, Science (Washington) 147, 45
(1965); Inorg. Chem. 6, 855 (1967).
[3] U. Schindewor, R. Vogeisgesang, and K . W. Boddeker,
Angew. Chem. 79, 1064 (1967); Angew. Chem. internat. Edit. 6,
1076 (1967).
[4] A . Eucken and R . Suhrinann: Physikaiisch-chemische Praktikumsaufgaben. Akadernische Verlagsgesellschaft, Leipzig 1960,
p. 103.
151 The equilibrium is strongly temperature dependent; under
the condidions used, the C6H6- spectrum becomes noticeable
below about -100 ”C.
Crystal Structure of 4-Thiouridine
By W . Suenger and K . H. Scheit [*I
After 4-thiouridine ( I ) had been discovered to be a constituent of t R N A of E.colilll,Lipsett and Doctor121 were able t o
show that tyrosine-specific tRNA from E.coli contains two
4-thiouridine units per molecule. Although the chemical and
physical properties of ( I ) in oligo- and polynucleotides [ 3 ~ 1
have been investigated, the function of this nucleoside in
E.coli-tRNA remains unclear. Since we had at o u r disposal
analytically pure, crystalline (1) f5.61, we attempted t o deterAngew. Chem. internat. Edit. J Vol. 8 (1969) J No. 2
Fig. 1 . Crystal structure of 4-thiouridine. Projection
onto 100. Bond lengths (A) and angles (”) not shown
in the Figure are:
= 101
= 103
= 110
= 107
= 119
= 110
= I19
= 109
= 110
= 115
a) Comparison of the nitrogen-containing rings in barium
5’-uridinephosphate [71 (2) and in ( 1 ) shows a similar arrangement of bond lengths and angles. The C-5-C-4 bond length
in ( I ) is 0.03 A greater than in (21, whereas the N-3-C-4
and N-3-C-2 bond lengths are shorter by 0.025 A, and the
bond angle C-2-N-I-C-6 is reduced from 124 t o 120’.
The bond lengths C-2-0-2 and C-4-S are characteristic for
keto structures [8,91. The six-membered ring is largely planar;
the ring atoms deviate from the “best” plane by n o more than
0.04 A but S and C-1 stand out from this plane by 0.48 and
-0.23 A respectively.
b) The ribose unit is puckered: the interatomic distances and
bond angles agree well with thosefound by other authors [7,101.
C-3‘ lies out of the “best” plane, which can be constructed
through C-l’, C-2’, C-4’, and 0-l‘,by 0.59 A, and is on the
same side as C-5‘; the ribose is therefore in the endo conformation.
c) The most surprising feature of the structure is the syn
conformation of the nucleoside. The angle of twist about the
glycosidic C-1 ‘-N-1 bond (as defined by Trueblood, Horn,
and L ~ z z n t i [ l o lis) +83 ’. As far as we know, this conforma-
tion has not previously been observed for any pyrimidine
d) The molecules are arranged in the crystal such that hydrophobic and hydrophilic regions are oriented along the
a axis. The nitrogen-containlng rings are stacked parallel to
one another, separated by about 3.3 A, and form a hydrophobic channel along this axis. The ribose units occupy the
interior of the unit cell and are bound to one another by
water molecules (one and a half per asymmetric unit).
Further refinement of the structure is in progress.
Received: October 21, 1968
IZ 916 IE]
German version: Angew. Chem. 81, 121 (1969)
[*I Dr.
W. Saenger and Dr. K . H. Sche~t
Max-Planck-Institut fur experimentelle Medirin
Abteilung Chemie
34 Gottingen, Hermann-Rein-Str. 3 (Germany)
[l] M . N . Lipsett, J. biol. Chemistry 240, 3975 (1965).
[21 M. N . Lipsett and B. P. Doctor, J. biol. Chemistry 242, 4072
[3] K. H . Scheit, Biochim. biophysica Acta 166, 285 (1968).
[41 K . H . Scheit, unpublished.
[ 5 ] K . H . Scheit, Chem. Ber. 101, 1141 (1968).
[6] K . H . Scheit, Tetrahedron Letters 1967, 113.
[71 E. Shefter and K. N . Trueblood, Acta crystallogr. 18, 1067
[8] E. Shefter and H . G. Mautner, J. Amer. chem. SOC.89, 1249
[9] E. Shefter and T. I. Kalman, Biochem. biophysic. Res. Commun. 32, 878 (1968).
[lo] K. N . Trueblood, P . Horn, and V. Luzzati, Acta crystallogr.
14, 965 (1961).
The complex HCo(PF&PH3 was also produced by treating
HCo(PF&CO with phosphine, showing that CO is displaced
by PH3 in preference to PF3.
Received: October 14, 1968
[Z 918 IE]
German version: Angew. Cheni. 8 / , 120 (1969)
['I Dr. J. M. Campbell and Prof. Dr. F.
G. A. Stone
Department of Inorganic Chemistry,
The University
Bristol (England)
111 E. 0. Fischer, E. Louis, and R . J . J . Schneider, Angew. Chem.
80, 122 (1968); Angew. Chem. internat. Edit. 7, 136 (1968).
[2] F. Klanberg and E. L . Muetterties, J. Amer. chem. SOC.90,
3296 (1968).
[3] Th. Kruck, W . Lang, and A . Engelinann, Angew. Chem. 77,
132 (1965); Angew. Chem. internat. Edit. 4 , 148 (1965).
By H. Burger and U.Goetze [*I
In contrast to the large number of compounds in which
silicon is bonded to elements of Groups IV to VII, only a few
silyl derivatives of the electron-deficient elements of Groups
I to 111 are knownrll. In most cases their formation could be
deduced only from subsequent reaction products 121. The first
examples of relatively stable, fully silylated derivatives of a
Group 111 element are the thallium compounds (R3Si),TI
(R = CH3 131. C2H5 [I]).
By means of the reaction
+ 3 (CH3)3SiCI + 6 Li
THF, -30°C
Hydridophosphinetris( trifluorophosphine)cobalt(1)
By J. M. Campbell and F. G. A . Stone[*]
Transition metal complexes containing PH3 as a unidentate
ligand have only recently become known[l,*]. Herein we
report the compound HCo(PF&PH3 ( I ) , which is the first
example both of a hydrido-phosphine metal complex and of
a phosphine-trifluorophosphinecomplex.
The new compound is a pale yellow sublimable solid (m.p.
25 "C) which may be prepared by irradiating mixtures of
HCo(PF3)4 131 and PH3 (molar ratio 1:2) for periods of up to
one hour by means of a mercury discharge lamp, o r for longer
periods by exposure to sunlight. The compound was isolated
from PF3, PH3, and unreacted HCo(PF& by fractionation
in a high vacuum system (10-6 torr), compound ( I ) being
retained at -46OC whereas HCo(PF3)4 is condensed at
-64°C. Final purification was accomplished using a lowtemperature distillation column (yield 20 %).
The complex ( I ) was characterized by its mass spectrum,
and by its infrared and nuclear magnetic resonance spectra.
The mass spectrum shows a parent peak at m / e 358 and other
major peaks corresponding to the fragment ions HCo(PF&PH;, HCO(PF~)~PH;,
H C O ( P F ~ ) ~ P HHCO(PF~)(PF~)PH;,
HCo(PF3)(PFz)PH;, etc.
The gas phase infrared spectrum shows vmax at 2369 (vP-H),
1967 (vCo-H), 1049 (8P-H), and 925, 885, and 851 cm-1
(P-F vibrations).
The 1H-NMR spectrum (pure liquid, TMS as internal reference) shows a doublet of quartets at T = 6.12, (int. 3, PH3)
with JP-H = 352 Hz and JF,P-H = 17.6 Hz, and a broad
absorption at T = 24.4 (int. 1, CoH). This spectrum suggests
that the hydrogen atom and the phosphine group are trans to
one another, the three trifluorophosphine groups being in the
equatorial positions of the trigonal bipyramid. The 19F-NMR
spectrum (liquid) consisted of two multiplets (separation
1117 Hz) centered at 9.8 ppm above CCI3F.
+ 6 LiCl
which is analogous to those used for the synthesis of
[(CH&Si]dGe and [(CH3)3Si]4Sn141, we succeeded in preparing and isolating tris(trimethylsily1)indium ( I ) . A yield
of 40% is obtainable only by adherence to the procedure
given since a higher reaction temperature and slow stirring
for prolonged reaction times favor reduction of InC13 according to
+ 3 Li
+ 3 LiCl
+ In
and simultaneously inactivate the lithium metal.
On sublimation, pure ( I ) is deposited in the form of greenishyellow crystals, which decompose under vacuum above 50 OC
in the dark and above about 0 ° C on exposure to daylight.
The decomposition products are indium and hexamethyldisilane; the presence of CH31n groups could not be established. In solution or in contact with its decomposition
products, compound ( I ) even decomposes below room
Compound ( I ) is extremely reactive toward 0 2 ; it is spontaneously inflammable in air and explodes at room temperature in a current of oxygen. Consequently, in order to
ensure controllable combustion during C H analysis, we had
to use a stream of Ar containing an increasing proportion of
0 2 . Owing to the sensitivity of the substance, which exceeds
that of [(CH&Si]zHg, the values obtained from the C, H.
and In analyses showed a scattering of up to i 10%.
Even after extreme care had been exercised in the preparation
of the sample, the I R spectrum invariably contained bands
due to oxidation products (initially the strong bands due to
an indium silanolate at 455 (vInO) and 895 cm-1 (vSi0) and
subsequently those due to [(CH3)3Sil20 at 330 and 1060
cm-1). It can be deduced from the way in which the spectra
change with time that ( I ) exhibits medium absorption at 311
cm-1, which can be assigned to vasSi31n, alongside those
bands arisingfrom internal Si(CH3)3vibrations; the possibility
that this band arises from decomposition products cannot be
completely ruled out.
Angew. Chem. internat. Edit.
Vol. 8 (1969) 1 No. 2
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crystals, structure, thiouridine
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