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Covalent HydrationЧNew Results Using 13C-NMR Spectroscopy.

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experienced by C-4 (Table I), whose resonance shifts to
72.4 ppm, i. e. into the region typical for "carbinol" carbons.
In addition, protonation at N-1 documents itself through
upfield shifts for C-2 and C-9. Protonation alone does not
change 6(4) significantly, since for the anhydrous cation ( I @)
(CF,COOH) we find a value of 159.2 ppm.
atoms C1, C2, N1 and N2 are nearly coplanar, about 0.5A
below the Mo atom. The most important distances and bond
angles are given in Figure 1 and Table 1.
The X-ray structure analysis confirms the S configuration of
the u-phenylethyl group. Before the configuration at the Mo
atom can be specified with the R,S-sy~tem[~],
rules for the
treatment of rr-bonded ligands must be developed.
Received: January 9, 1975 [Z 182 IE]
German version: Angew. Chem. 87, 379 ( 1 975)
CAS Registry numbers:
( I ) . 54750-18-4
(4)
(3)
[I] S. J . La Placa and 1. Bernal thank the U. S. Atomic Energy Commission
for support of this research while they were at Brookhaven National Laboratory. Part 30 of the series "Optically Active Transition Metal Complexes". This
work was supported by the Deutsche Forschungsgemeinschaft and the Fonds
der Chemischen 1ndustrie.-Part 29: H . Brunner and M . Langer, J. Organometal. Chem. 87, 223 (1975).
123 H. Brunner and W A. Herrmann, Chem. Ber. 105, 3600 (1972).
[3] H. Brunner and W A. Herrmann, Chem. Ber. 106, 632 (1973).
[4] R. S. Cahn, C . Ingold, and V: Prelog, Angew. Chem. 78, 413 (1966);
Angew. Chem. internat. Edit. 5, 385 (1966).
Covalent Hydration-New
spectroscopy"l
Results Using
(5)
Pyrido[3,4-b]pyrazine (1,4,6-triazanaphthalene)(3) was formulated in 1 N H,S04 initially as protonated monohydrate
(#)[51 and later as dihydrate (5)[51.In the 13C-NMR spectrum
(Fig. 1) we find two resonances at 73.7 and 74.5 ppm. Therefore,
( 5 ) must be present, whose structure is also compatible with
the other 6( '3C)-values. With the exception of C-9 all carbon
resonances are strongly shielded as a result of protonation at
N-6 and NH-substitution at C-9 and C-10. Since only five
C(spz) resonances are observed, a mixture of two monohydrates can be ruled out.
3C-NMR
c-2. c-3
I
c-5
By Ulrich Ewers, Harald Giinther, and Lothar Jaenicke"]
The structure of covalent hydrates that are formed by addition
of water to C N double bonds in nitrogen heterocycles121has
been elucidated so far mainly with the help of UV spectroscopy[2*31. Wenow show that more preciseand reliable information is obtained from I3C-NMR spectroscopy because of the
sensitivity of chemical shifts to hybridization changes and
substituent effects.
According to previous
quinazoline (1,3-diazanaphthalene) exists in CDCl3 as neutral species (I) and in 2 N
H2SO4 as protonated hydrate (2). Hydrate formation is
recognized '3C-NMR spectroscopically by the strong shielding
C-8
I c-10 c-7
140
150
iio
rn
120
I
iio
100
90
80
70
t-S('3C)[PPm]
Fig. 1. ' T - N M R spectrum of 1.4.6-triazanaphthalene in 1 N H2S04; &values
refer to TMS as standard (cf. footnote in Table 1).
H OH
New results were obtained through I3C-NMR spectroscopy
for pteridine (1,3,5,8-tetra-azanaphthalene)
( 6 ) . Owing to slow
hydration in aqueous solution, freshly prepared solutions
of (6) at first show F('3C)-values that are also observed in
CDCl,['I (Table 1). However, after equilibration (12 h) a
Table 1. S("C)-values (in ppm, relative to TMS) in heteroaromatics and their hydrates [a].
(1)
CDC13
C-2
C-3
C-4
156.1
-
161.1
C-5
C-6
128.1
128.8
(2)
2~ H,SO,
148.1
-
CDCL
150.2
148.4
(5)
1 N H2S04
72.4
~
-
A
CDCI,
(6)
(6)
H20
74.5
160.0
158.7
73.7
-
~
-
164.6
164.2
H20
73.7,
73.9,
75.1
C-9
C-10
135.1
129.3
151.3
126.0
7
118.3
129.2
129.2
131.7
130.4
121.4
155.8
-
147.8
122.8
146.3
139.0
133.5
-
124.0
108.8
145.2
128.2
148.8
149.9
153.4
154.7
-
153.4
154.7
135.9
134.9
-
CHOH
(7)+(8)
C-8
A
f
(3)
C-7
~
C(SP2)
r
A
\
158.4, 154.4, 151.8, 149.5, 145.7, 142.1, 137.8, 124.9
[a] Assignments based on additivity relations and "C.'H coupling constants; preliminary assignments are in italics.
Following recent results [8] the older assignments for S(2)and S(4)in ( I ) [9] and (6) [7] must be reversed. Measurements
were made at 22.63 MHz with a Bruker HX-90 spectrometer. External dioxane served as reference in all cases.
Conversion of the &values to the Srmsscale was based on SrMs(dioxane)=67.4 ppm.
[*] Prof. Dr. H. Giinther and Dipl.-Chem. U. Ewers
Institut fur Organische Chemie der Universitat
5 Koln, Ziilpicher Strasse 47
Prof. Dr. L. Jaenicke
Institut fur Biochemie der Universitat
5 Koln. An der Bottmiihle 2 (Germany)
354
spectrum is obtained that shows, besides the signals due to
(6);three CHOH-resonances at 73.7, 73.9, and 75.1 ppm. We
assume that, already at pH 6.8 in addition to the monohydrate
(7)"l the dihydrate (8) is formed in almost equal amount.
This interpretation would also best explain the new signals
Angew. Chem. internal. Edit.
/ Vol. 14 (1975) / N o . 5
with evolution of gas when heated to above its melting range
of 36-39°C in a sealed tube.
found for sp2 carbons (Table 1). For a trihydrate only 3
additional resonances are expected, whereas a mixture of three
different monohydrates should yield 15 signals. Products of
ring opening reactions cannot explain the spectrum, since they
contain only sp2 carbons and, in particular, should display a
characteristic carbonyl resonance; (8) has so far been obtained in protonated form at pH 216].
The results for (3) and (6) each show that one heteroaromatic
ring is preserved during hydrate formation. This finding is
consistent with the fact that pyridine and pyrimidine do not
form hydrates. The existence of a pteridine dihydrate under
physiological conditions as substrate of xanthine oxidase could
explain the formation of leukopterine as a degradation product
of pteridine cofactorsiIo1.
Received: January 9, 1975 [Z 181 IE]
German version: Angew. Chem. 87, 356 (1975)
CAS Registry numbers:
( 1 ) . 253-82-7; (2). 54698-98-5; (31, 254-86-4; ( 5 ) . 54698-99-6;
(6). 91-18-9: (7). 14130-90-6; ( 8 ) . 14130-91-7
[I]Applications of '3C-Resonance Spectroscopy, Part 19. This work has
been supported by the Deutsche Forschungsgemeinschaft and the Fonds
der Chemischen 1ndustrie.-Part 18 see: U . Ewers, H. Giinther,and L. Jaenicke,
Chem. Ber. 107, 3275 (1974).
[2] A. Albert and W L. F. Amarego, Advan. Heterocycl. Chem. 4, 1 (1965).
[3] D. D. Perrin, Advan. Heterocycl. Chem. 4, 43 (1965).
[4] M. J . Cho and 1. H. Pitman, J. Amer. Chem. SOC. 96, 1843 (1974);
and lit. cited therein.
[5] 7: J . Batterham, J. Chem. SOC.C 1966,999.
[6] A. Albert, 7: J . Batterham, and J . McCormack, J. Chem. SOC.B 1966,1105.
[7] I/. Ewers. H. Giinther. and L. Jaenicke, Chem. Ber. 106, 3951 (1973).
[8] U . Ewers, H. Giinther, and L. Jaenicke, Chem. Ber. in preparation.
[9] R. J . Pugmire, M. J . Robins, D. M. Grant, and R. K. Robins, J. Amer.
Chem. SOC.91, 6381 (1969).
[lo] H. Rembold, H. Metzger, and W Gutensohn, Biochim. Biophys. Acta
230, 117 (1971).
Metal-Stabilized C-Protonated Diazomethane:
A Methanediazonium Complex[']
By Wolfgang A. Herrmannp]
On reaction with simple aliphatic diazo compounds transition metal hydrides are generally converted into the corresponding alkyl derivatives, which can be explained as formal
carbene insertion into the polar metal-hydrogen bondi2-31.In
the course of investigations designed to elucidate the diazo
method leading to carbene complexes of transition metalsr41,
diazomethane has now been stabilized as an intact, subsequently protonated molecule by coordination to a metal.
Addition of an excess of diazomethane ( I ) at -85°C to
a THF solution of cyclopentadienyltricarbonyltungsten hydride (2) followed by a gradual raising of the temperature
to +25"C affords a dark red neutral compound (3) which
can be isolated by column chromatography. Compound (3)
is extremely air-sensitive in solution, and slowly decomposes
Chemisches lnstitut der Universitat
84 Regensburg 1. Universitatsstrasse 31 (Germany)
Vol. 14 (1975)
I21
I31
Complete elemental analysis and spectroscopic data show
the new complex to possess a diazomethane ligand which
has been protonated at the originally sp2-hybridized carbon
atom, and is bound to the metal via the terminal nitrogen
atom, as a characteristic structural component. While the
stretching vibrations of the two metal carbonyl groups are
observed in the IR spectrum (benzene) at 1968vs and
1886 c m - ' vs, the bands at 1635s and 1595 cm-' m are to
be assigned to the stretching vibrations of the complexed
azo functioni5*61. The 'H-NMR spectrum (60MHz; CDCl3;
external TMS) establishes the presence of the cyclopentadienyl ring (~=4.17ppm,singlet) as well as the newly formed
methyl group (T =6.37 ppm, singlet); absorption no longer
occurs in the high-field hydride region. The proposed structure
is further supported by the mass spectrum of (3) which shows,
in addition to the intense molecular peak (mle 350 for la6W),
successive elimination of CH3, N2, and the two CO groups
(70eV; direct inlet at 10°C; ion source 30--40°C).
Theabove reaction which entails a lowering of the coordination number of the central metal is the first example of CO
substitution effected by diazomethane, even though it is associated with a 1,4-hydrogen shift"]. The ligand CH3N2 which
corresponds to the highly unstable methanediazonium ion
assumes the function of a neutral three-electron donor in
the complex.
Procedure:
All operations are carried out with rigorous exclusion of
oxygen and moisture (N2atmosphere).-A precooled (- 35 "C)
approximately 0.25 M ethanol-free solution of ( 1 ) (10mmol)
in diethyl etherca1is added dropwise to a magnetically stirred
solution of (2)IZ1(1.67g, Smmol) in THF (100rnl) at -85°C
in a thermostated darkened Schlenk flask (programmed cryostat LAUDA K 120W). After 1 h at -85°C the mixture is
warmed to room temperature over 12 h and stirring continued
to complete the reaction (12 h). Chromatography of the concentrated crude product at +lO°C over silica gel 60 (Merck
7734; I = 80, 0 = 1.8cm) with benzene permits elution of a
rapidly migrating yellow zone whose residue affords the methyl
derivativeC5H5W(CO)3CH3121(26mg,
1.5 %)on high vacuum
sublimation at 55°C. A second red zone is concentrated and
rechromatographed under the same conditions. The complex
(3) initially obtained as a red oil yields fine crystals on reprecipitation (diethyl etherin-pentane; OOC) and is analytically pure
after recrystallization from diethyl etherin-pentane (1 :2) at
- 100°C and several hours' drying in high vacuum (0°C).
Yield 1.08g (62%).
Received: January 24, 1975 [Z 192 IE]
German version: Angew. Chem. 87, 358 (1975)
CAS Registry numbers:
( I ) . 334-88-3; ( 2 ) , 12128-26-6; ( 3 ) . 54774-68-9
[l] Complex Chemistry of Reactive Organic Compounds, Part 7.--Part
6: W A. Herrmann, J. Organometal. Chem. 84, C 2 5 (1975).
[2] E. 0. Fischer, W Hafner, and H. 0. Stahl, Z. Anorg. Allg. Chem. 282,
[*] Dr. W. A. Herrmann
Angew. Chem. internat. Edit.
dHg
Ill
1 No. 5
47 (1955).
355
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