state is +3. Thus, Ga3Te31is the first mixed valency compound that contains an element of the third main group
with the oxidation states + 2 and +3. The macromolecular
connection corresponds to the following structural formula:
Fig I. View along [OOlJ in the one-dimensional structural element of
Ga,Te,l: G a = 0 , I = 0.T e = O ; each tellurium atom forms a trigonal pyramid with three gallium atoms (bond lengths Ga-Te: 2.633(1) to
2.693(5) A)
In the structural arrangement, the strands that are extended parallel in the [OOl] direction are approximately
hexagonally close-packed with respect to their central
axes. The successive macromolecules are each translationally equivalent in the [IOO] direction. The shortest intermolecular distances (3.863(5) A) are found between the terminal iodine atoms and between those tellurium atoms that
are involved in the tetrahedral coordination of the Ga"'
centers.
Received: March 10, 1986;
revised: May 6, 1986 [Z 1696 IE]
German version: Angew. Chem. 98 (1986) 7 2 5
dral and octahedral sites,['-31 and are not reduced on treatment with H2 even at high temperatures (770 K). In calcined Cu/y-A1,03 catalysts, copper is similarly present in a
spinel-like p h a ~ e , [ ' . ~CuO
. ~ ] segregating out at high copper
loading^;'^] in this catalyst, however, the C u z @ions are reducible on treatment with H,. We considered it worthwhile
investigating the nature of species in reduced samples of
bimetallic Ni-Cu/y-A1,03, which are used as catalysts for
hydrogenation and other reactions. It has been reported
that the presence of copper favors the formation of Ni" in
reduced samples.'61 Presence of nickel similarly seems to
promote the reduction of supported copper. The actual nature of the nickel and copper species in reduced bimetallic
catalysts has not been described hitherto except for the
identification of the Nio species in Ni23-Cu77/y-AI2O3
samples by Erfl et aI.['l
We have investigated Ni-Cu/y-Al,03 catalysts over the
entire composition range by means of X-ray photoelectron
spectroscopy (XPS) and Auger electron spectroscopy
(AES)."] The total metal loading in the catalysts studied was
5 wt-Yo; samples with C u to Ni ratios 75:25, 50:50, 25:75,
were studied along with the catalysts containing only C u
and Ni. The catalyst samples were first calcined at 870 K
for 8 h in air. The spectra of the catalysts were recorded
after reducing them in situ in the sample preparation
chamber of the spectrometer (720 K, 6 h, 300-torr hydrogen pressure). The 2p level of A1201 (74.0 ev) and the
4f,,, level of Au (83.6 eV) were used as references for the
XPS binding energies.
Calcined Ni-Cu/y-AI2O, catalysts show the presence of
Ni?@in
. the form of NiA1204 with a Ni(2p3,,) binding energy of -856.6 eV. The Cu(2p3,,) binding energy in the
calcined samples was close to that of CuA1,04. On reduction, XPS in the core level region clearly reveals the nature
of the nickel species. The N i ( 2 ~ , , ~spectra
)
show the presence of both Nio and Ni2@with binding energies of 853.2
eV and 856.3 eV respectively, in samples with high copper
content (Fig. 1). The relative concentration of Ni" increases with increasing copper content, the Ni" being totally absent in reduced Ni/y-Al,O,. Variation of the rela-
[ I ] InTeHal: R. Kniep, A. Wilms, H.-J. Beister, K. Syassen, Z. Naiurforsch.
836 (1981) 1520: GaTeHal: R. Kniep, A. Wilms, H.-J. Beister, Muler
Res. Bull. 18 (1983) 615.
[2] 1nTe: J. H. C . Hogg, H. H. Sutherland, Acra Crystallogr. Sect. 832 (1976)
2689; GaTe: M. Julien-Pouzol, S. Jaulmes, M. Guittard, F. Alpini, ibid.
835 (1979) 2848.
[3] Crystallographic data of Ga,Te,l: 1408 (1462) reflections; R =4.8%;
P n ~ 2 , U: = 11.168(4), b = 19.529(10), c=4.102(2) A; Z = 3 : pcnlcd=4.00g/
cm'. Further details of the crystal structure investigation may be obtained
from the Fachinformationszentrum Energie, Physik, Mathematik GmbH,
D-7514 Eggenstein-Leopoldshafen2 (FRG), OR quoting the depository
number CSD-52010, the names of the authors, and the journal citation.
[4] G. Gerlach, W. Honle. A. Simon, Z. Anorg. Allg. Chem. 486 (1982) 7 .
Ni
N I 75- Cu2S
N I 50 - C U 50
Nature of Ni and Cu Species in
Reduced Bimetallic Ni-Cu/Alz03 Catalysts
By Gopinathan Sankar and C. N . Ramachandra Rao*
It is well known that NiZOions in calcined Ni/y-A1203
catalysts are in a spinel-like phase, occupying both tetraheN. R Rdo, G. Sankar
Solid State and Structural Chemistry Unit
lndian institute of Science
Bdngalore 560 012 (India)
I
I
I
I
1
851
8 55
859
863
867
[*] Prof. I>r. C
Angew. Chem. Int Ed. Engl. 25 11986) No. 8
fb
Lev1
-
Fig. I. Ni(Zp,,,,) spectra (ESCA) of reduced Ni-Cu/y-Alz03 catalysts:
Eb=binding energy.
0 VCH Veriagsgesel1,schajimbH. 0-6940 Weinheim, 1986
0570-0833/86/0808-0753 $ 02.50/0
753
r
Simple Synthesis of
1-Amino-1-cyclopropanecarboxylic Acids from
tert-Butyl Isocyanoacetate and Epoxides;
Synthesis of
Alkyl 5,6-Dihydro-4H-1,3-oxazine-4-carboxylates
6ol
0
t
0
-
50
*/*
cu
Fig. 2. Variation of the relative
concentration of Ni" with copper
content.
100
tive concentration of Nio with copper content is shown in
Figure 2. In contrast, the Cu(2p3,,) spectra of the reduced
Cu-Ni/y-Al,03 catalysts show little change with composition. From the XPS data it cannot be decided whether Cue
is formed in addition to Cuo, as noted earlier by Ertl et
aL1I1Formation of Cue has been suggested in the literature18] in the case of reduced Cu/y-Al,O, catalysts. We
have employed Auger electron spectroscopy to examine
the presence of Cue and Cuo in reduced Ni-Cu/y-AlZO3
catalysts. The spectra d o indeed show the presence of both
species (Fig. 3). The relative proportion of Cue increases
with the increasing copper content; accordingly, the AES
spectrum of Cu25-Ni75/y-A1203 does not show the presence of Cue.
I.I!
I
I
I
934
924
914
+
-
Ekinlev1
By Ulrich Schollkopf,' Bernd Hupfeld and Reinhold Gull
1-Amino- 1-cyclopropanecarboxylicacids 8 are currently
attracting attention, mainly because of their proven or potential biological activity."] Although methods for the synthesis of this class of compounds have already been described in the literature,['.21a relatively simple, inexpensive
and productive synthetic method is still lacking. We describe here a synthesis starting from tert-butyl isocyanoacetate 1 and from (inexpensive) epoxides 3.13] The lithiated ester 2 reacts with the epoxides 3 in the presence
of boron trifluoride ether[41to give the tert-butyl 4-hydroxy-2-isocyanoalkanoates 4. The substitution takes
place with inversion of configuration at the less hindered
carbon atom of the epoxide. The compounds 4 are then
mesylated to compounds 5 . The mesylates readily undergo
base-induced cyclization to the tert-butyl l-isocyano-l-cyclopropanecarboxylates 7.Owing to the considerably large
difference in size between the isocyano group and the tert-
2
1
Li
Ni50-Cu50
I
904
Fig. 3. CufL.,M4.,M4.,) Auger
electron spectra of reduced
Ni-Cu/y-Al,O,
catalysts;
E,,,=kinetic energy of the
electrons.
C02tBu
4.X=H
5, X = Mes
6
R3
-
H,,
R1 T R ~
The present study not only establishes the presence of
Ni', NiZe, Cuo and Cue in the reduced bimetallic Ni-Cu/
y-A1203 catalysts, but also shows how the relative proportion of Nio increases with increasing copper content just as
that of Cuo increases with increasing nickel content. We
are presently carrying out EXAFS (Extended X-ray Absorption Fine Structure) studies on these bimetallic catalysts.
Received: March 24, 1986;
supplemented: June 3, 1986 [Z 1710 IE]
German version: Angew. Chem. 98 (1986) 736
3-9
R'
8
R'
R3
1,s
trans :cis
b.bl
CAS Registry numbers:
Ni, 7440-02-0; Cu, 7440-50-8
[ I ] G. Ertl, R. Hierl, H. Knozinger, N. Thiele, H. P. Urbach, Appl. SurJ Sci. 5
(1980) 49.
[2] R. Hierl, H. Knozinger, H. P. Urbach, J . Catal. 69 (1981) 475.
[3] M. Lo Jacono, M. Schiavello, A. Cimino, J . Phys. Chem. 75 (1971)
C02H
H2N
7
a
b
c
d
e
H
H
H
CH,
H
CIHS
CH,
H
-(CH&-
H
H
H
CH,
H
6.5: I
6.5: 1
29515
4
Yields [Yo][c]
5
7
8
9
54
66
76
72
80
80
77
85
84
90
63
66
33
66
67
60
62
62
69
68
93
89
89
91
89
1044.
141 R. M. Friedman, J. J. Freeman, F. W. Lytle, J . Catal. 55 (1978) 10.
151 M. Lo Jacono, M. Schiavello in B. Delmon, P. A. Jacobs, G. Ponchelet
(Eds.): Preparation of Catalysts, Elsevier, Amsterdam 1976, p. 473.
[6] A. Roman, B. Delmon, J . Catal. 30 (1973) 333.
171 ESCA-3 Mark 11 Spectrometer, VG Scientific.
[8] M. Lo Jacono, A. Cimino, M. Inversi, J. Catal. 76 (1982) 320.
754
0 VCH Verlagsgesellschaft mbH. 0-6940 Weinheim, 1986
[a1 Referred to C02tBu and R', R2. [b] Racemates; one enantiomer shown. [c]
Yields referred to 1 , 4, 5 , 7 and 4 .
[*] Prof. Dr. U. Schollkopf, Dip].-Chem. B. Hupfeld, Dr. R. Gull
lnstitut fur Organische Chemie der Universitat
Tammannstrasse 2, D-3400 Gottingen (FRG)
0570-0833/86/0808-0754$ 02.50/0
Angew. Chem. Int. Ed. Engl. 25 (1986) No. 8