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Direct Structural Proof for the Pentazole Ring System in Solution by 15N-NMR Spectroscopy.

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independent molecules). Enraf-Nonius CAD4 diffractometer, monochroM o k , , radiation,
4292 independent reflections with
2.0=s//s22.0', full matrix refinement with 2616 reflections [f>2cT(f)];
R=0.0676, R,,=0.0491 [~==.(o'+O.O009F:,)-']. Further details of the
cryztal structure investigation are available on request from the Fachinforrnationszentrum Energie Physik Mathematik, D-75 14 Eggenstein-Leopoldshafen 2 on quoting the depository number C S D 51 288, the names of
the authors and the full citation of the journal.
On the Absolute Configuration of ( )-Tartaric Acid
By Hartmuth Buding, Bertold Deppisch, Hans Musso, *
and Giinther Snatzke
The absolute configuration of (+)-tartaric acid from
grape juice was determined in 1951 by Bijuoet et al.['I for
the rubidium salt using the anomalous dispersion of zirconium K, X-rays. This result was questioned by Tanaka
et at.':' in 1972, but DunitzL3'has shown it to be correct. In
the meantime new structure determinations on tartrate^'^]
have appeared and there is independent evidence that macroscopic crystal forms can be related to molecular chirality by X-ray methods.['' According to Prelog et aLF6]each
new example that reconfirms Bijvoet's method is welcome.
Therefore, we present results that led us unintentionally to
the determination of the ( R , R ) configuration for (+)-tartaric acid 1.
(+)-2,3-Butanediol 2 was obtained from ( + ) - 1 by reduction of the carboxy groups according to a conventional
procedure,"' and was then transformed into ( -)-2,3-butanedithiol 3 by the method of Corey and Mitra.@]The reaction of 3 with the racemic diketone 4 yielded a mixture of
diastereumeric bisdithioacetals. The second component
eluting on chromatography was shown by Bijvoet's X-ray
diffraction analysis to be the enantiomer 5."' The chiral
centers in ( - ) - 3 therefore have the ( R , R ) configuration.
Since the formation of 3 from ( + ) - 2 must involve a
Walden inversion, ( + ) - 2 has the ( S . S ) configuration and
the starting material is therefore (R,R)-(+ ) - 1 .
m0 HO
(R,i?)-(-)-3 +
OH 0
Independently, the ( S , S , S , S ) configuration was determined for the carbon framework of the tricyclic ketone
(+)-4(obtained by hydrolysis of 5 ) from the negative Cot[*] Prof. Dr. H. Musso. Dr. H. Buding
lnstitut fur Organische Chemie der Universitat
Richard-Willstatter-Allee 2, D-7500 Karlsruhe (FRG)
ton effect that is ubserved.['I The ( R , R ) configuration of
( + ) - 1 and the ( S , S , S , S )configuration of ( + ) - 4 are linked
here by the structure determination of 5 . In this way
(R,R)-(+ ) - 1 is reconfirmed through the optical activity of
Received: January 21, 1985 [Z 1181 IE]
German version: Angew. Chem. 97 (1985) 503
[ I ] J. M. Bijvoet, A. F. Peerdeman, A. J. van Bommel, Nature (Lundoni 168
(1951) 271.
121 J. Tanaka, F. Ogura, M. Kuritani, M. Nakagawa, Chimia 26 (1972) 471;
N. Sakabe, K. Sakabe, K. Ozeki-Minakata, J. Tanaka, Acra Crvstallugr.
B2# (1972) 3441: J. Tanaka, C. Katayama, F. Ogura, H. Tatemitsu, M.
Nakagawa, J . Chem. SUC.Chem. Commun. 1973, 21; J. Tdnaka, K. OzekiMinakata, F. Ogura, M. Nakagawa, Nature Phys. Sci. 241 (1973) 22.
[3] J. D. Dunitz: Methods of Crystal Stnrrture Ano/ysi.s. Cornell University
Press, lthaca 1979, p. 143ff.
[4] L. Bohaty, R. Frohlich, 2. Knsfallogr.., Krrstallgeum., Krisra/lph.v.s.. K r f stalkhem. 164 (1983) 261, 291.
15) L. Addadi, 2.Berkovitch-Yellin, 1. Weissbuch, M. Lahav, L. Leiserowitz,
J. Am. Chem. Sue. 104 (1982) 2075; 105 (1983) 6615; L. Addadi, Z . Berkovitch-Yellin, 1. Weissbuch, J. van Mil, L. J. W. Shimon, M. Lahav. L. Leiserowitz, Angew. Chem. 97 (1985) 476; Angew. Chem. I n t . Ed. Engl. 24
(1985) 466.
[6] V. Prelog, D. Bedekovic, Helu. Chrm. Acta 62 (1979) 2285. especially pp.
2292, 2293.
171 J. J. Plattner, H. Rapoport, J. Am. Chem. Soc. 93 (1971) 1758.
[8] E. J. Corey, R. B. Mitra, J. Am. Chem. Soc. 84 (1962) 2938.
191 Preparative, experimental, and theoretical details: H. Musso et al., Chem.
Ber.. in press.
Direct Structural Proof for the Pentazole Ring
System in Solution by "N-NMR Spectroscopy**
By Raffaello Miiller, John D. Wallis, and
Wolfgang von Philipsborn*
Benzenediazonium chloride la reacts with lithium azide
in methanol to produce phenyl azide 3a and molecular nitrogen. Huisgen and Ugi[" discovered that the reaction
proceeds by two mechanisms. For one of them it was proposed that phenylpentazole 2a is an intermediate."] Its
symmetry accounts for the equal distribution of an "N label, originally in the terminal N atom of the diazonium
salt, between the decomposition products phenyl azide 3a
and molecular nitrogen (Scheme 1). Subsequently, a series
of crystalline p-substituted phenylpentazoles was isolated[41
at low temperature ( - 30"C), and recently the structure of
the most stable of these, p-dimethylaminophenylpentazole
2b, was confirmed by X-ray crystallography at 128 K.['I
We have now used "N-NMR spectroscopy to observe this
unstable compound in solution at 238 K and to monitor its
decomposition at higher temperatures.
The natural abundance "N-NMR spectrum of a solution of a crystalline sample of 2b in CDC13 measured at
40.56 MHz (9.4 T) and 238 K is shown in Figure 1 a. Even
at this temperature the pentazole has partially decomposed
during the long measurement time (40 h) to molecular nitrogen and p-dimethylaminophenyl azide 3b. The nitrogen
[*] Prof. Dr. W. von Philipsborn, DipLChem. R. Muller
Organisch-chemisches lnstitut der Universitat
Winterthurerstrasse 190, CH-8057 Zurich (Switzerland)
Dr. J. D. Wallis
Laboratorium fur Organische Chemie der
Eidgenossischen Technischen Hochschule
Universitatstrasse 16, CH-8092 Zurich (Switzerland)
Prof. Dr. B. Deppisch
lnstitut fur Kristallographie der Universitat
D-7500 Karlsruhe (FRG)
Prof. Dr. Ci. Snatzke
Abteilung fur Chemie, Lehrstuhl fur Strukturchemie der Universitat
D-4630 Bochum 1 (FRG)
Angew. Chem. Int.
Ed. Engl. 24 (19851 Nu. 6
"N-NMR Spectroscopy, Part 14. Thib work was supported by the Royal
Society of London (J. D . W . ) a n d the Swiss National Science Foundation. We thank Prof. J . D . Dunirz for his interest.-Part 13: [l].
0 V C H Verlaysge.sellschafi mbH. 0-6940 Weinheim. 19#5
057#-0833185/06#6-0513 $ 02.5010
5 13
Table I . "N chemical shifts in 6 values (k0.3 p p m ) relative to external
CHIl5NOZ:solvent CDCI? 1151.
a , R = H;
b, R
N-2,5, N-2'
- 80.0
- 27.1
- 134.6
- 134.4
- 27.5
- 135.3
- 135 0
- 333.2 [a]
-33.5.0[d, b]
- 146.2
- 147.0
[a] Data tiom a solution of 80 mg of crystalline 2b dissolved in 10 m L of
CDC13,0 . 0 7 ~in Cr(acac),. [b] Data of an authentic sample of 3b, 348 mg in
10 mL CDCI,, 0 . 0 7 ~in Cr(acac),. [c] llata from a crystalline sample of[2(5)"NI-pentazole Zb, 99% "N, 25 mg in 10 mL of CDC13, 0.06 M in Cr(acac)+
[d] Same sample as in [c], after decomposition.
Scheme 1.
produces a broad resonance at 6 = - 7316,71and the presence of 3b is confirmed by comparison with the spectrum
of an authentic sample (Fig. lb). The assignment of the
four resonances of 3b is based upon literature data on
phenyl azides.Ix1These were the only resonances observed
when the spectrum was remeasured after the sample had
been left at room temperature for 24 h. The four remaining
signals in Figure l a are ascribed to the pentazole derivative 2b, one to the -N(CH& group (6= -324.6) and three
to the all-nitrogen five-membered ring (N-I: 6 = -80.0, N2,5:6=-27.1, N-3,4:6=+4.9,Table 1).
The resonance at 6 = - 80.0 is assigned to the only tricoordinated N atom N-1, by analogy with other a~oles.''~
Using additive shielding increments['"] evaluated from
azoles, a range of 6 = -70 to -90 for N-I is predicted.
The shielding of the tricoordinated N atoms decreases in
the series I-methylpyrazole (6 = - 180.8),~''1
2-methyl-1,2,3triazole (S= - 134.0),1'1 2-methyltetrazole (S= - 105.3),191
and the pentazole 2b (6 = - 80.0). The assignments of N2,5 and N-3,4 were made on the basis of the spectrum
(Fig. 2a) of a sample of 2b labeled with I5N at N-2, which
was prepared from the corresponding diazonium salt l b
labeled at the terminal nitrogen.'121The resonances of N2,5 and N-3,4, while in the expected range predicted by extrapolation from triazoles and tetrazoles, could not be reproduced by application of additive shielding increments.["'] On decomposition of 2b, the ''N label appeared
as expected in the central position of the N 3 group of 3b
and in the molecular nitrogen"'] (Fig. 2b).
NCH, l7 -2b73b
.. . .. ---.
.. . . .. .
- ...-
Fig. I . "N-NMR Spectra (40.56 MHz) ot' a) pentazole Zb, 0 . 0 4 ~in CDCI,,
238 K (see also Table I [a]) and b) authentic azide 3b, 0.21 M in CDCI,, 253 K
(see also Table 1 [bj). The weak signal at 6 = -73 is probably due to N 2 originating from decomposed azide; the asterisk indicates electronic spikes.
5 14
0 VCH Verlaq~gesellschaffmhH.
0 - 6 9 4 0 Weinheim. 1985
Fig. 2. "N-NMR Spectra (40.56 M H z ) of a) (2(5)-"N]-pentazole Zb, 0 . 0 1 3 ~
in CDC13, 253 K (see also Table I [ c ] )and b) labeled pentazole 2b (0,013 M ,
CDCl3) during decomposition to [2-"N]-3b and labeled " N = '"N[13] at
273 K.
- 8
It is thus confirmed that 2b also contains a pentazole
ring in solution. The electron-attracting power of the pentazole group is demonstrated by the deshielding of the dimethylamino N atom ( S = -324.6) compared to that in
N,N-dimethylaniline (6 = - 338 t 2). A similar effect is observed when the pentazole group is replaced by C N
( 6 = -325.4) or CHO (6= -323.1), and an even greater effect is produced by an NOZ group (S= -316.5).['" The
crystallographic results indicate that the inductive effect of
the pentazole group is similar to that of the nitro group.
Hence, it may be concluded from the I5N-NMR data that
the pentazole substituent is not as good a x-acceptor as the
nitro group.
0S7(1-~1833/85/0606-VSI4 $ 02 SO/O
Received: February 26. 1985:
revised: March 29, 1985 [Z 1194 IE]
German version: Angew. Chem. 97(1985) 515
Angew. Chem. I n ( . Ed. Engl. 24 11985) No. 6
CAS Registry numbers:
Ib.CI 100-04-9; Zb, 58402-54-3; "N-Zb, 96445-25-9; 3b, 18523-44-9; I5N3b, 96445-26-0; LiN,, 19597-69-4.
[ I ] C. M. Addms, W. von Philipsborn, Magn. Reson. Cbem. 22 (1985) 130.
[2] R. Huisgen, I . Ugi, Chem. Ber. YO (1957) 2914; 1. Ugi, R. Huisgen, ibid.
91 (1958) 531.
[3] 1. Ugi, R. Huisgen, K. Clusius, M. Vecchi, Angew. Cbem. 68 (1956)
[4] 1. Ugi, H. Perlinger, L. Behringer, Chem. Ber. 91 (1958) 2324.
[5] J. D. Wallis, J. I>. Dunitz, J. Chem. Soc. Cbem. Commun. 1983. 910.
[6] A signal at the same position and of similar width was obtained with a
saturated solution of gaseous N2 in CDCli containing Cr(acac), ( 0 . 0 7 ~ )
at 233 K.
[7] The "N resonance of labeled "N- I4N was reported to appear as a relatively sharp line at S= -70.5 (in cyclopropane, 233 K, recalculated rel.
to CHINO2 as ext. standard); cf. J. G. Green, G. R. Dubay, N. A. Porter,
J A m . Chem. Sor. 99 (1977) 1264. For a discussion of the chemical shifts
and line widths of N2 see also [13].
[S] J. Muller, Z . Nuturjiirsch. 8 3 4 (1979) 437.
[9] R. Muller, W. von Philipsborn, unpublished.
[lo] M. Witanowski, L. Stefaniak, G. A. Webb in G. A. Webb (Ed.): Annu.
Rept. NMR Specrrosc.. Yol. 118, Academic Press, London 1981, p. 77.
[ I l l 1. I . Schuster, C. Dyllick-Brenzinger, J. D. Roberts, J . Org. Chem. 44
(1979) 1765.
(121 Treatment of N.N-dimethyl-l,4-diaminobenzene
in C H 3 0 H / H 2 0( 5 :1)
at - 10°C with a molar equivalent of NaI5NO2(99% 15N)in a minimum
volume of H 2 0 gave, after stirring for 4 h, a solution of the corresponding diazonium chloride labeled with I5N at the ,B-N atom. Cooling to
-30 'C, dilution with an equal volume of cold C H 3 0 H , and treatment
with methanolic LiN3 yielded the desired pentazole as previously described. 14)
[I31 The signal of the labeled "N- I4N appears as a sharp line at S = -70. I
in good agreement with [7]. It is assigned to truly dissolved N 2 and is
only observed with labeled material because of the low concentration.
The broad NZ absorption centered at 6 = -73 in Figures I and 2b probably results from gaseous NZ in micro-bubbles and the associated local
field inhomogeneity.
(141 J. Dorie, B. Mechin, G. Martin, Org. Magn. Reson. 12 (1979) 229. T h e
published chemical shift data were recalculated relative t o CH,"NO2 as
an ext. standard.
[IS] The "N-NMR spectra were measured on a Bruker AM-400 w.b. spectrometer at 40.56 MHz in 20-mm tubes with Cr(acac), as a relaxation
reagent (AT=0.8 s , a=23", no proton decoupling).
coordinating properties of S20, since no structural investigations are available for the mononuclear complexes 1''I
and 2,[31and since the binuclear complex 3J4]whose structure has been confirmed by X-ray analysis, contains S20
6(dppe)21r(Sz0)]C1 1 , dppe: bis(dipheny1phosphino)ethane
[Cp2Nb(SzO)Cl]2, Cp: $-cyclopentadienyl
[Mo(SzO)(SzC-NEt,)zl, 3
We have prepared the brown disulfur complex 5 by
reaction of the tetrahydrofuran(THF)-stabilized complex
fragment [Cp*Mn(CO),] (Cp* = I$-pentamethylcyclopentadienyl), which is formed via photolysis of 4 in THF,''I
with excess sulfur. 5 was then converted to the red complex 6 by air oxidation.'61 The mononuclear neutral complex 6 is a suitable model compound for the study of the
S,O ligand.
Table 1. Spectroscopic data for the complexes 4 - 6
v(C0) [cm
7 [a]
k(C0) [ N . c m - ' ] [b]
By Max Herberhoid,* Bertram Schmidkonz,
Manfred L. Ziegler, and Thomas Zahn
Dedicated to Professor Helmut Behrens on the occasion
of his 70th birthday
Free disulfur monoxide, S20, wltich is stable in the gas
phase below 1 torr for several days, decomposes to SO,
and polysulfur oxides."] Like the isovalent and isoelectronic SO,, it is non-linear."]
S 2 0 can be formed as a complex ligand by the oxidation
of S2 ligands. However, the S 2 0 complexes reported so far
only allow tentative conclusions to be made regarding the
[*] Prof. Dr. M. Herberhold, DipLChem. B. Schmidkonz
Laboratorium fur Anorganische Chemie der Universitat
Universitatsstrasse 30, D-8580 Bayreuth
Prof. Ur. M. L. Ziegler, DipLChem. T. Zahn
Anorganisch-chemisches lnstitut der Universitat
Im Neurnheimer Feld 270, D-6900 Heidelberg (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
Angew Chem Int Ed Engl 24 (1985) No. 6
I3C-NMR [c]
2002 s
1917 vs
1993 vs
1946 vs
2000 vs
1952 vs
'H-NMR [c]
Disulfur Monoxide as Complex LigandPreparation and Molecular Structure of
[a] In THF. [b] Calculated according to F. A. Cotton, C. S. Kraihanzel, J . Am.
Chem. Soc. 84 (1962) 4432. [c] In CDC13, 0°C.
Table 1 summarizes the characteristic I R and NMR data
of the complexes 4-6. According to the force constants
k ( C 0 ) of the carbonyl vibrations, which can be calculated
from the v ( C 0 ) frequencies, the back-bonding from the
metal to the CO ligands decreases upon replacement of a
CO group in 4 with S, or S,O. The acceptor character of S2
is higher than that of CO; this observation was also made
in a n earlier study on [CpRe(CO)2S2].171Apparently, S, is
able to withdraw more charge from the complex fragment
[Cp*Mn(CO),] than carbon monoxide. A further, but
somewhat smaller increase in the acceptor ability occurs
upon oxidation of the S, ligand to S20.
According to the X-ray structure determination of 6
(Fig. I), the disulfur monoxide ligand is coordinated to the
metal via both sulfur atoms. The Mn-S bonds are long
and somewhat different; the sulfur atom bearing the oxygen, S(2), exhibits pyramidal geometry and is further away
from the metal than the terminal S(1). The S-S axis is
roughly parallel to the ring plane of the Cp* ligand. The
oxygen atom of the S,O ligand is directed away from the
Cp* ring; the dihedral angle S20/CSMe, is 54.3". In comparison to free S20, the S-S and S-0 bonds of coordi-
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spectroscopy, solutions, structure, nmr, 15n, proof, pentazole, direct, ring, system
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