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Detection of Heavy Metal Ions by ESR Spectroscopy.

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shows the metal splitting given while the other signal consists
merely of a doublet due to a proton. We assign this signal to
Table 1, ESR data of the heavy metal complexes formed from (1) and various
cations in pyridine at room temperature.
traction with CHC13 was debenzoylated with sec-butylamine
in MeOH. Purification [DEAE-cellulose column (0.1-0.3 M
NEt3HC03)and RP 8 (HzO)] afforded crystalline (9) as the
triethylammonium salt in 7096 yield. The 'H-NMR spectrum
[DzO,adenine-H: 7.76,7.90,7.95,7.97,
8.08, 8.17;HI' (doublet): 5.82, 5.92, 6.171 and chromatogram [PEI-cellulose
(NH4HC03)]are consistent with the data in the literature['].
As expected (9) is cleaved enzymatically by phosphodiesterase from snake venom but not by phosphodiesterase from
spleen[*].
Received August 1, 1979 [Z 346 IE]
German version: Angew. Chem. 91, 1007 (1979)
111 I. M. Kerr, R. E. Brown, Proc. Nat. Acad. Sci. USA 7S, 256 (1978); A. Zilberstein, A. Kimchi, A. Schmidt, M. Revel, ibid. 75, 4734 (1978).
121 L. Carrasco, Nature 272, 694 (1978).
[3] R. H . Hall, Biochemistry 3, 6 (1964).
[4] C. B. Reese, Tetrahedron 34, 3143 (1978).
[5] J. H. van Boom, P. M . J. Burgers, C. van der Morel, C. H . M. Verdegaal, C.
Wille, Nucl. Acids Res. 4, 1047 (1977).
(61 J. Engels, Angew. Chem. 91, 155 (1979); Angew. Chem. Int. Ed. Engl. 18,148
(1979).
[7] E. M. Martin, N.J. M. Birdsall, R. E. Brown, I . M. Kerr, Eur. J. Biochem. 95,
295 (1979).
[XI K. K. Ogiluie, N . Y. Theriault. Tetrahedron Lett. 1979, 21 11.
Complex
Cation
an
[GI
aMeC.1
[GI
AH
[GI
g
(2)
(3)
Pb2'
Zn2"
CdZe
3.95
4.00
3.90
7.3
-
0.45
0.45
0.35
1.9993
2.0046
2.0044
Et,TI"
"free"
3.25
2.35
0.60
0.35
2.M)35
2.0048
(4)
(3[bl
16)
"'Cd 3.95 [a]
" T d 4.13 [a]
11.75
-
[a] Determined by spectral simulation. [b] Diethylthallium hydroxide was provided by U.Bergler.
the free ligand (6). Its proton coupling constant is considerably smaller and thus reveals the failure of complex formation
to take place.
As a result of the different g factors and metal splitting it is
possible to detect several ions simultaneously. Figure 1
shows the hyperfine structure observed on reaction of (1)
with CdZ@and Pbz@ions in pyridine. The lines marked x
correspond to the chelate (4), whereas the unmarked lines
are assigned to the chelate (2).
X
X
Detection of Heavy Metal Ions by ESR
Spectroscopy[**]
By Hartmut B. Stegmann, Martin Schnabel, and Klaus
ScheJJeiJ'l
The high sensitivity and the pronounced selectivity of
ESR spectroscopy have prompted us to examine the potential of this method for the detection of heavy metal ions. The
proposed technique requires ligands which form complexes
with cations and can subsequently be transformed into paramagnetic systems. Moreover, both the complex and the free
ligand should be insoluble in water in order to permit twophase reactions. These requirements are satisfied, for example, by 3,6-di-tert-butyl-2-(2-hydroxybenzylidenamino)hydroquinone (l)l'l.
The ligand (1)reacts in pyridine with Pbz@,ZnZQ,or Cd2@
to form chelates which are oxidized to paramagnetic complexes by atmospheric oxygen, silver oxide, or lead dioxide.
Some experimental values are listed in Table 1.
The spectra of two paramagnetic species can be observed
simultaneously in the (1)/Et2T1@systemrz1.The complex (5)
Prof. Dr. H. B. Stegmann [ 1' . Prof. Dr. K. Scheffler, M.Schnabel
Institut fur Organische Chemie der Universitat
Auf der Morgenstelle 18, D-7400 Tiibingen 1 (Germany)
[ 1' To whom correspondence should be addressed.
["I This work was supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industne.
['I
Angew. Chem. In[. Ed. Engl. I8 (1979) No. 12
i l
Fig. 1. ESR spectra of the Cd*" chelate (4) ( x ) and the Pb2' chelate (2) in p y
ridine at room temperature.
The above cations can also be detected if they are present
in aqueous phase. The aqueous solution is shaken with a
benzene solution of the ligand (1) in the presence of 10% of
pyridine. After separation, the organic phase is dried over sodium sulfate and transferred directly to the ESR sample
tube. Some lead dioxide may be added as oxidizing agent.
The ESR parameters of the resulting complex agree with the
values listed in Table 1. Working in this way with a
molar solution of zinc acetate and a lo-' mol/l concentration of
the ligand (1)in the organic phase the signal of (3) can be recognized without difficulty with a signal to noise ratio of
15 : 1. This sensitivity can be increased by two orders of magnitude on computerized spectral accumulation.
0 Verlag Chemie, GmbH, 6940 Weinheim, 1979
0570-0833/79/12t2-0943
$ 02.SO/O
943
Received: August 6, 1979 [Z 347 IE]
German version: Angew. Chem. 91, 1007 (1979)
[l] The compound (f)is formed by reaction of 2-amino-3.5-di-terf-butylhydroquinone with 2-bydroxybenzaldehyde.
[2) K. B. Ulmschneider, H . B. Stegmann, K . Scheffler, G. Viertel, 2. Naturforsch.
B 33, 237 (1978).
Structure and Reactions of Methylenesulfur
Tetrafluoride'**'
By Hans Bock, James E. Boggs, Gert Kleemann, Dieter Lentz,
Heint Oberhammer, Eva Maria Peters, Konrad Seppelt, Arndt
Simon, and Bahman Solouki'']
Dedicated to Professor Gerhard Fritz on the occasion of his
60th birthday
\\I1
F
M
;"
H2C=SF4 is easily prepared by reaction of SF,-CH2Br
and n-C4H9Li at -llO°C['i. This methylene compound is
thermally more stable than all known phosphorus and sulfur
ylides and metal carbene complexes. In the gaseous state at
lo-* torr, it is stable up to 650 "C. The vibrational spectra['1
and the 'H-, 13C-, and 19F-NMR spectra['] are in agreement
with an ylidic double bond.
10
11
12
14
13
15
16
17
19
18
IE [ e V J
Fig. 1. He(1) PE spectrum of H2C=SF4 with qualitative assignment by comparison with SF4.
The resonance formula with the double bond, however, is
much more important than in other ylides: the spectroscopic
bond order is 1.8[*1; the charge on the carbon atom is -0.6,
as calculated by ab initio
These findings are supported by the photoelectron spectrum (Fig. 1). This shows a single band at 10.65 eV which is
assigned to ncs ionization. Compared with phosphorus
ylides, which have first ionization potentials below 7 eVr4I,in
H2C=SF4 the energy difference to the radical cationic state
is increased by the fluorine substitution.
Formal addition of (excited[4b1)CH2to the F4S sulfur electron pair (cf. Fig. 1) generates the mcs- and ucs bondsf4];the
radical cationic states of the type nF and uSFremain nearly
unchangedf5].
The IR, Raman, NMR, or PE spectra do not readily indicate the orientation of the methylene group or its possible axial e equatorial interchange, e. g. by pseudorotation of the
trigonal bipyramidal F4SC skeleton. The NMR data, however, indicated that the probably planar H2C group must be
oriented either axially (a) or equatorially (e).
['I
Priv.-Doz. Dr. K. Seppelt [ '1. Dip1.-Chem. G. Kleemann, Dr. D. Lentz
Anorganisch-chemisches Institut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg 1 (Germany)
Prof. Dr. H. Bock, Dr. 8. Solouki
Institut fur Anorganische Chemie der Universitat
Niederurseler Hang, D-6000 Frankfurt am Main 50 (Germany)
CI
F
H
F
H
Low temperature crystal structure analysis[61,electron diffractionfs1,and an ab initio calculation (Table 1) all resulted
in a trigonal bipyramidal structure similar to that of SF4, but
with a much smaller equatorial angle FSF. The methylene
group is oriented in the plane of the axial fluorine atoms.
This can be explained by the valence shell electron pair repulsion model Only in this configuration can the ncselectron density easily be accommodated, and the equatorial
~
Crystal
structure [6]
Electron
diffraction
171
ab initio
F.SF.
FS,
HCH
159.2, 159.4
156.0, 156.1
155.3
(82.2, 92.2)
170.44
96.44
120.91
159.5 (15)
157.5 (15)
155.0 (20)
108 [a]
170.0 (2.0)
97.0 (2.0)
122.0 [a]
159.1
156.2
154.2
106.6
169.9
98.8
123.3
$02.50/0
Angew. Chem. I n [ . Ed. EngI. 18 (1979) No. 12
s=c
C
Angles
I"]
To whom correspondence should be addressed.
This work was supported by the Fonds der Chemischen Industrie, the
Deutsche Fonchungsgemeinschaft, and the Robert A. Welch Foundation.
SCF [3]
~
Distances [pm] S F.
S F.
Prof. Dr. A. Simon, Dipl.-Chem. E. M. Peters
Max-Planck-Institut fur Festkorperforschung
Heisenbergstrasse 1, D-7000 Stuttgart 80 (Germany)
0 Verlag Chemie, CmbH, 6940 Weinheim, 2979
F
Table 1. Structural data of H>C=SFs.
Prof. Dr. H. Oberhammer
lnstitut fur Physikalische und Theoretische Chemie der Universitat
Auf der Morgenstelle 8, D-7400 Tiibingen 1 (Germany)
944
H
Fig. 2. Structural possibilities of H2C=SF4. According to the valence shell electron pair repulsion model the observed "axial" position of the protons is preferred. Qualitatively the observed structure (left) may be rationalized by linking a
tetrahedron with a n octahedron through two bent bonds.
Prof. J . E. B o g s
Department of Chemistry, University of Texas
Austin, Texas 78712 (USA)
['I
["I
F
H
[a] Estimated.
0570-0833/79/1212-o944
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