Nanocrystalline zintl phases from main-group metal chlorides and magnesium anthracene or activated magnesium

Article abstract of DOI:10.1002/(SICI)1099-0682(199811)1998:11<1699::AID-EJIC1699>3.0.CO;2-C

Ga, Tl, Sn, Pb, As, Sb, Bi, Cd, and Hg chlorides react with magnesium anthracene · 3 THF (MgA), anthracene-activated magnesium, or active magnesium (Mg*) in THF, generating the respective Mg intermetallics in a nanocrystalline or amorphous state (Eqs. 1-3). Mg intermetallics accessible through the wet-chemical route can be exploited by metathetical exchange reactions for the preparation of other, highly active intermetallics and alloys; EXAFS investigation of X-ray amorphous Cu-Sn and Pd-Pb solids thus prepared (Eqs. 13 and 14) shows that they are true bimetallic alloys (solid solutions).

Full text of DOI:10.1002/(SICI)1099-0682(199811)1998:11<1699::AID-EJIC1699>3.0.CO;2-C

FULL PAPER
Magnesium Anthracene Systems, 10[᭛]
Nanocrystalline Zintl Phases from Main-Group Metal Chlorides and
Magnesium Anthracene or Activated Magnesium
´
Ingo Abraham, Lorraine E. Aleandri, Borislav Bogdanovic*, Uwe Kolb, Martin Lagarden, and Klaus Schlichte
Max-Planck-Institut für Kohlenforschung,
Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany
Fax: (internat.) ϩ 49(0)208/306-2980
E-mail: bogdanovic@mpi-muelheim.mpg.de
Received April 14, 1998
Keywords: Magnesium anthracene / Active magnesium / Zintl phases / Magnesium intermetallics / EXAFS spectroscopy
Ga, Tl, Sn, Pb, As, Sb, Bi, Cd, and Hg chlorides react with
magnesium anthracene · 3 THF (MgA), anthracene-activated
magnesium, or “active magnesium” (Mg*) in THF, gene-
rating the respective Mg intermetallics in a nanocrystalline
or amorphous state (Eqs. 1–3). Mg intermetallics accessible
through the wet-chemical route can be exploited by
metathetical exchange reactions for the preparation of other,
highly active intermetallics and alloys; EXAFS investigation
of X-ray amorphous Cu–Sn and Pd–Pb solids thus prepared
(Eqs. 13 and 14) shows that they are true bimetallic alloys
(solid solutions).
Introduction
In recent publications[1] we have reported the preparation
of a series of so-called inorganic Grignard reagents from
transition-metal chlorides and organomagnesium com-
pounds or “active magnesium” (Mg*). These soluble sys-
tems can be used as reagents for the synthesis of intermet-
allics and alloys in a finely divided, usually nanoparticulate,
state[1]. In contrast to transition-metal chlorides, it was
found[1b] that chlorides of heavier group 12Ϫ15 metals
(MCln) in THF react with magnesium anthracene·3 THF [2]
(MgA), Mg*, or ordinary magnesium powder in the pres-
ence of catalytic amounts of MgA[3], with formation of
magnesium intermetallics (MgqM), also in a finely divided,
highly active state[4]; the reactions can be described by eqs.
1Ϫ3. When MgA is used as the reducing agent (Eq. 1), the
reaction progress can be monitored by measuring the in-
crease in anthracene (A) concentration in the reaction solu-
tion with time. In some cases, it is advantageous to run the
reaction shown in Eq. 1 in two steps. In the first step, MCln
is reduced to the metallic state in a highly active form
(M*, Eq. 1a); subsequently, M* with additional MgA is
transformed into MgqM (Eq. 1b). In the following, we give
an account of the preparation, characterization, and pos-
sible application of magnesium intermetallics obtained via
Results
Mg؊Ga and Mg؊Tl Intermetallics
The Ga-rich Zintl phase Mg2Ga5[6] has previously been pre-
pared in bulk form by melting stoichiometric mixtures of
high-purity Mg and Ga metal sealed in Ta[6a] or pyrex cru-
cibles[6c]. The preparation of Mg2Ga5 in a finely divided,
highly reactive crystalline form can now be achieved via a
two-step reaction. In the first step (Eq. 4) GaCl3 is reduced
with MgA at low temperature to give a highly active gal-
lium (Ga*) suspension in THF. After separating the active
metal from MgCl2 and anthracene, Ga* can be converted,
with additional MgA, into Mg2Ga5 (Eq. 5). Mg2Ga5 is ob-
tained as a black pyrophoric powder contaminated with
MgCl2, A, and THF (Table 3; Expt. 1).
these routes[1b][4][5]
.
[᭛]
´
Part 9: R. Benn, B. Bogdanovic, M. Brüning, H. Grondey, W.
Herrmann, H.-G. Kinzelmann, K. Seevogel, Chem. Ber. 1993,
126, 225
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Mg؊Sn and Mg؊Pb Intermetallics
The XRD pattern of the Mg2Ga5 thus prepared (Figure
1) is in accordance with that reported in the literature[7]
.
Mg forms Zintl phases of the type Mg2E, E ϭ Ge, Sn,
Pb[8] with group 14 metals which crystallize in CaF2 anti-
isomorphous structures. Their high melting points reflect
the heteropolar character of the bonds between the respec-
tive elements. The preparation of Mg2E in bulk form has
been carried out by melting the components in an inert at-
Figure 1. X-ray powder diffraction patterns of Mg2Ga5, prepared
from GaCl3 and MgA; o, diffraction line of Ga
mosphere in sealed iron or corundum crucibles[8][12]
.
The reaction of SnCl2 with MgA in THF, as a method
for the preparation of Sn or Mg2Sn, both in a finely divided
state, has been investigated in some detail (Table 4). If the
reaction is conducted in the 1:1 molar ratio at room or low
temperature (Expts. 4.1 and 4.2), a highly reactive, pyro-
phoric, black form of metallic Sn of 97Ϫ98% purity (Sn*,
Eq. 7) is obtained. Sn* prepared at low temperature (Expt.
4.2) shows only diffuse Sn and no Mg2Sn diffraction lines
in the XRD spectrum. The high reactivity of Sn* prepared
according to Eq. 7 is demonstrated by, amongst other
things, its reaction with MgA in THF leading to Mg2Sn
(see below Eq. 10; Expt. 4.6); commercial Sn powder does
not react with MgA under such conditions.
The MgϪTl Zintl phase MgTl[8][9] can now be prepared
in a microcrystalline (nanocrystalline?) form by treating
TlCl with an excess of MgA in THF (Eq. 6; Expt. 3.2).
MgTl was obtained as a silvery shining powder with the
composition Mg0.88TlCl0.01(CH2)0.2. A DSC analysis of the
powder showed a weak endothermic peak at 202.7°C (onset
temperature; MgTl ϩ Tl eutectic; ref.[10], 202°C) and an
intense endothermic peak at 351.3°C (onset temperature)
Reaction of SnCl2 with MgA in the molar ratio of 1:2
gives a mixture of Sn* and Mg2Sn (Expt. 4.3), which, with
additional SnCl2 can again be converted into Sn* (Eq. 8).
corresponding to the melting point of MgTl (ref.[10]
358°C).
,
This result, together with the Mg/Tl ratio of 0.88:1 found
through elemental analysis, reveals the presence of Tl in the
MgTl thus prepared. However, the XRD powder pattern of
this material (Figure 2) exhibited only the diffraction lines
of MgTl[11]. The Tl particles if present are, therefore, most
likely X-ray amorphous.
In order to produce Mg2Sn free of Sn*, it is necessary to
react SnCl2 with MgA in an excess amount with respect to
Eq. 9 (e.g. in the molar ratio 1:4, Expt. 4.4). The Mg2Sn
obtained is free of Sn or of the SnϪMg2Sn eutectic, accord-
ing to DSC analysis. The TEM photograph of the Mg2Sn
thus prepared (Figure 3) reveals aggregates of nonuniform
nanocrystals of 10Ϫ50-nm size.
Figure 2. X-ray powder diffraction pattern of MgTl, prepared from
TlCl and MgA
On the basis of the widening of the strongest diffraction
line in the XRD of this material, an average particle size
of 40 ± 4 nm has been estimated, in agreement with the
TEM result.
The progress of the reaction of Sn halides with MgA in
the molar ration of 1:4.1 at 0°C is represented in Figure 4.
Under these conditions (Expt. 4.5) SnCl2 and SnBr2 yielded
Mg2Sn with specific surface areas of 70 and 130 m2gϪ1
,
respectively. X-ray powder diffraction showed sharp Mg2Sn
diffraction lines only. SnI2 (Figure 4) under the same con-
ditions did not react completely, while hardly any reaction
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Magnesium Anthracene Systems, 10
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Figure 3. High-resolution TEM photograph of Mg2Sn prepared 3A/Mg2Sn is, in both cases, only reached after ca. 50 h. The
from SnCl2 and MgA
reaction is further slowed down when Sn* is separated from
MgCl2 and A prior to the reaction with additional MgA
(Ϫ᭜Ϫ). Since the reduction of SnCl2 by MgA to Sn* (Eq.
7) is apparently much more rapid than the conversion of
Sn* with MgA in Mg2Sn, it is reasonable to assume that
Sn* also acts as an intermediate in the direct formation of
Mg2Sn from SnCl2 and MgA (Eq. 10). The X-ray diffrac-
tion pattern of Mg2Sn prepared according to the two-step
reaction (Expt. 4.6) is shown in Figure 5.
The preparation of Mg2Pb by the wet-chemical method
can be carried out by using either stoichiometric amounts
of MgA (Eq. 11) or commercial Mg powder with MgA act-
ing as a “phase transfer catalyst”[1f][13] (Eq. 12). Reaction
of PbCl2 with MgA in the molar ratio of 1:3.7 in THF
(Expt. 5.1) yielded microcrystalline pyrophoric intermetallic
Mg2Pb which, according to its elemental composition
(Mg1.84Pb) and X-ray diffractogram, contained minute
at all was observed with SnF2, probably due to the insolu- amounts of Pb. On the other hand, Mg2Pb which was
bility of SnF2 and MgF2 in THF.
shown using XRD to contain only traces of Pb (Figure 6)
Figure 4. Progress of the formation reaction of Mg2Sn from Sn halides (SnX2) and MgA (1:4.1; [SnX2] ϭ 0.06 mol/l) in THF at 0°C;
Ϫ᭿Ϫ, SnCl2, one-step reaction; Ϫ Ϫ, SnCl2, two-step-reaction; Ϫ᭜Ϫ, SnCl2, two-step reaction, Sn* separated from MgCl2 and A;
Ϫ᭡Ϫ, SnBr2; Ϫ Ϫ, SnI2; ϪϫϪ, SnF2
The preparation of Mg2Sn with a high specific surface was obtained by reacting PbCl2 with Mg powder and 10
area (85 m2gϪ1) and free of Sn* is also possible via the two- mol-% of MgA at 0°C (Expt. 5.2).
step reaction. Accordingly, SnCl2 is first reacted with MgA
in the molar ratio of 1:1 at room temperature, thus generat-
ing Sn*, and then at 0°C with 3 additional equivalents of
MgA, giving Mg2Sn (Expt. 4.6).
Cu(Mg)؊Sn and Pd؊Pb Alloys from Mg2Sn and Mg2Pb and the
Respective Metal Halides
As can further be seen in Figure 4, the rate of the two-
step reaction (Expt. 4.6; Ϫ Ϫ) is somewhat slower than
According to preliminary investigations, the highly reac-
that of the direct reaction (Ϫ᭿Ϫ); but the final ratio of ca. tive Mg intermetallics accessible by the wet-chemical route
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Figure 5. X-ray powder diffraction pattern of Mg2Sn prepared and for the hydrodechlorination of chlorofluorocarbons
from SnCl2 and MgA in the two-step reaction
(CFCs)[18]
.
In order to provide starting materials with a high disper-
sion and reactivity, Mg2Sn and Mg2Pb utilized for the reac-
tions with metal halides were prepared at low temperatures
(Expts. 4.8 and 5.1). Mg2Sn prepared at low temperatures
(Expt. 4.7) is, indeed, highly dispersed, as demonstrated by
its broad but weak diffraction lines in XRD.
Reactions of Mg2Sn with CuCl2 and of Mg2Pb with
PdCl2 in the molar ratio of 1:2 (THF, room temperature)
gave in quantitative yields solids of the compositions ca.
Cu1.6Mg0.2Sn(MgCl2)0.1(CH2)0.4 (Expt. 6.1) and ca.
Pd1.9Pb(MgCl2)0.1Cl0.1(CH2)0.9 (Expt. 6.2), respectively.
From the compositions of the solids and the amount of
Mg2ϩ analyzed in THF solutions, it can be concluded that
exchange reactions have taken place in the sense of Eqs. 13
and 14. In the first case (Eq. 13), however, these reactions
amount only to roughly 80%.
According to the CuϪSn[14] and PdϪPb[15] phase dia-
grams, intermetallic compounds of the compositions Cu2Sn
and Pd2Pb are not known. The X-ray diffractogram for
wet-chemically prepared Cu(Mg)ϪSn alloy showed weak
Figure 6. X-ray powder diffraction pattern of Pb2Sn prepared from
PbCl2 and Mg powder in the presence of 10 mol-% of MgA; o,
diffraction lines of Pb
diffuse reflections (Cu?, Sn) only. After heating a sample to
[19]
145 or 400°C, weak diffraction lines for Cu6Sn5
ap-
peared in the X-ray powder pattern. XRD of the wet-
chemically prepared PdϪPb alloy showed the presence of
Pb, but upon programmed heating to 300 or 400°C (in steps
of 50°C), the spectrum showed weak diffraction lines for
Pd3Pb[20]
.
In order to gain more information about their structure,
both nonannealed X-ray amorphous alloys were investi-
gated using extended X-ray absorption fine structure (EX-
AFS) spectroscopy.
Structural Characterization of the Wet-Chemically Prepared
Cu(Mg)؊Sn and Pd؊Pb Alloys Using EXAFS
The Fourier transforms of the k3χ(k) functions at the Cu-
(Eqs. 1Ϫ3) can be exploited for the preparation of other and Sn-K absorption edges of the Cu(Mg)ϪSn alloy are
intermetallics and alloys in a highly active state. As demon- dominated by a single peak which at the Cu-K edge (Figure
strated in the following, wet-chemically prepared Mg2Sn 7) is markedly split. An adaption of the Fourier-filtered
and Mg2Pb react with Cu and Pd chlorides, respectively in k3χ(k) functions requires, for the Sn central atom, a single
THF with exchange of Mg by the metal in question. The coordination shell of Cu atoms. For the Cu central atom, a
reactions can thus be envisaged as a route for the prep- fit with only a single coordination shell is not possible. Two
aration of intermetallics and alloys complementary to that coordination shells consisting of Cu and Sn backscatterers
of applying “inorganic Grignard reagents”[1] (see Introduc- are needed to reproduce the Cu-K EXAFS spectrum. Al-
tion).
though only a limited k range (3Ϫ10 AϪ1) is available, a
˚
CuϪSn[14] and PdϪPb alloys[15] are accessible via metal- clear distinction between Cu and Sn backscatterers is pos-
lurgical methods. A colloidal PdϪPb alloy has recently sible. Using only Cu backscatterers, no fit is possible. The
been prepared by Bönnemann et al.[16] by means of co-re- structural parameters of the Cu(Mg)ϪSn alloy as deter-
duction of the corresponding metal salts. PdϪPb metal mined by EXAFS spectroscopy are summarized in Table 1.
combinations can be used as catalysts for the cis-selective
The agreement between the values for the CuϪSn dis-
hydrogenation of alkynes to alkenes (Lindlar catalyst)[16][17] tance (2.68 A) and for the EXAFS Debye-Waller factor σ
˚
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Magnesium Anthracene Systems, 10
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Figure 7. Unfiltered experimental (solid line) and fitted (broken line) k3χ(k) functions and their Fourier transforms of the Cu(Mg)ϪSn
alloy at the Cu- (A) and Sn-K (B) absorption edges
Table 1. Structural parameters of the Cu(Mg)ϪSn alloy before an- using Cu-K EXAFS spectroscopy, demonstrating that a
nealing determined by EXAFS spectroscopy
pure Cu phase is present.
The Fourier transforms of the experimental k3χ(k) func-
˚
˚
absorber
backscatterer
r [A]
N
σ [A]
tions at the Pd-K and Pb-LIII absorption edges of the
Pb(Mg)Pd alloy also show one single peak with a small
shoulder at low r values. The nonfiltered, experimental and
fitted k3χ(k) functions and their Fourier transforms are
shown in Figure 8. The curve-fitting procedure shows that
the experimental k3χ(k) functions at both the Pd-K and at
the Pb-LIII absorption edge are dominated by the contri-
bution of Pd backscatterers. Therefore, from the analysis of
the Pb-LIII absorption spectrum, it can be concluded that
the Pb atoms are mostly alloyed to Pd. Variations of the
structural parameters of the Pd backscatterers influence the
agreement between nonfiltered, experimental and fitted
k3χ(k) functions much more than variations of the struc-
tural parameters of the Pb backscatterers.
Sn
Cu
Sn
2.68
6.5
2.6
2.9
0.113
0.114
0.098
Cu
2.68
Cu
2.56[a]
[a] The CuϪCu distance corresponds to that of the bulk metal.
(0.113 and 0.114) obtained by analysis of the Cu and Sn
data shows the structural parameters to be reliable. Al-
though no further-reaching model can be proposed, the
structural data (Table 1) allow the following conclusions to
be made: (1) for the Sn central atom only Cu backscatterer
atoms are observed; the neat Sn phase can therefore only
be present to a very low extent, the greatest part of Sn being
alloyed with Cu; (2) structural models which postulate the
majority of Sn atoms to be on the surface of Cu particles
can be excluded because for the Sn central atom ca. 6.5 Cu
backscatter atoms are found; (3) the low number of atoms
in the coordination shells is characteristic of extremely
small metal particles having a large proportion of surface
atoms and consisting of no more than a few dozen metal
atoms. Coordination numbers determined by EXAFS spec-
troscopy are influenced by the quality of samples, thus for
more accurate determination of coordination numbers
further experiments are necessary. This is also especially
true for EXAFS investigations of the annealed sample,
which exhibit diffractometrically detectable phases and
Both k3χ(k) functions can be reproduced by inclusion of
only two coordination shells of Pb and Pd atoms. For the
final fits, the EXAFS Debye-Waller factors σPbϪPd and
Table 2. Structural parameters of the PdϪPb alloy before annealing
determined by EXAFS spectroscopy
˚
˚
absorber
backscatterer
r [A]
N
σ [A]
Pb
Pd
Pd
Pb
Pb
Pd
2.8
3.6
2.8
2.8
4.2
1.9
2.6
4.6
0.103[a]
0.144
0.103[a]
0.091
which point to higher coordination numbers; (4) Cu back-
˚
[a] For the final fits, the EXAFS DebyeϪWaller factors σPbϪPd and
scatterers at a distance of 2.56 A are shown to be present σPdϪPb were constrained to the same value.
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σPdϪPb were constrained to the same value. The results of corresponding Zintl phases Mg3M2* in a finely divided,
the curve fitting procedures are listed in Table 2.
highly active, pyrophoric state (Eq. 16).
The agreement between the values for the PbϪPd dis-
tance (2.80 A) derived from both k χ(k) functions confirms brown, X-ray amorphous powder, with a specific surface
the reliability of these structural parameters too.
Mg3As2 (Expt. 7.1) is obtained by this method as a deep-
3
˚
area of 167.7 m2gϪ1. After annealing (400°C), the presence
Figure 8. Unfiltered experimental (solid line) and fitted (broken line) k3χ(k) functions and their Fourier transforms for the PbϪPd alloy
at the Pt-LIII (A) and the Pd-K (B) absorption edges
The data allow the following conclusions to be made: (1)
only Pd backscatterers can be seen in the first coordination
shell of the Pb atoms, suggesting that Pb is predominantly
alloyed with Pd and at most a small fraction of Pb atoms
exist as a pure Pb phase; (2) Pb atoms contribute signifi-
cantly to the Pd-K EXAFS spectrum; a considerable part
of the Pd atoms are therefore alloyed to Pb atoms; (3) be-
of Mg3As2 was proved by X-ray diffraction[24] (Figure 9).
BiCl3 reacted with Mg* in THF (Expt. 7.2) to give a black
pyrophoric powder with the composition Mg1.45Bi-
(MgCl2)0.06(CH2)0.8, whose X-ray diffractogram (without
annealing; Figure 10) exhibited strong diffraction lines for
Mg3Bi2[25] and weak ones for Bi.
cause Pd atoms can also be seen in the first coordination
shell of Pd atoms, and the determined PdϪPd distance of
˚
2.8 Pd A is close to the PdϪPd distance in bulk Pd (2.75
˚
A), a considerable fraction of Pd atoms seem additionally
to be present in the form of bulk Pd.
Reaction of SbCl3 with MgA in THF (Eq. 17; Expt. 7.3)
yielded a highly pyrophoric powder with the composition
Mg1.49Sb(MgCl2)0.03(CH2)1.4. The carbon in the solid was
shown to be present in the form of THF and anthracene.
An X-ray powder pattern of the sample (Figure 11) after
annealing (400°C) demonstrated, however, the presence of
a mixture of Mg3Sb2[26] and Sb.
Mg؊As, Mg؊Sb and Mg؊Bi Intermetallics
As, Sb and Bi (M) together with Mg form Zintl phases
of the formula Mg3M2[8]. Mg3As2 has been prepared by
Zintl and Huseman[21] from As vapour and Mg at elevated
temperatures under hydrogen. Mg3Sb2 and Mg3Bi2 have
been obtained in bulk form by melting stoichiometric mix-
tures of pure metals in sealed steel crucibles.[8][21][22]
A highly reactive, pyrophoric form of magnesium (Mg*)
with specific surface areas of 13Ϫ36 m2gϪ1 can be gener-
ated by decomposing MgA in an organic solvent, such as
toluene (Eq. 15).[23] By reacting AsCl3, or BiCl3 in THF
Mg؊Cd and Mg؊Hg Intermetallics
CdCl2 reacted with commercial Mg powder (molar ratio
with the Mg* thus obtained, it is possible to prepare the 1:2.2) in THF in the presence of catalytic amounts MgA
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Magnesium Anthracene Systems, 10
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Figure 9. X-ray powder diffraction pattern of Mg3As2, prepared and the presence of ca. 30% of Cd in the reaction solution,
from AsCl3 and Mg* (after annealing, 400°C)
probably indicate a more complex reaction course than that
given by Eq. 18.
The reaction of HgCl2 with MgA (molar ratio 1:3.8) in
THF takes place with a rapid liberation of 2.0 mol anthra-
cene/mol HgCl2 and formation of a finely divided solid hav-
ing the composition Mg1.32Hg (Expt. 8.2); the X-ray pow-
der pattern of the solid exhibited only sharp diffraction
lines for MgHg[28] (Figure 13; Eq. 19).
Figure 12. X-ray powder diffraction pattern of MgCd (o, MgCd3),
prepared from CdCl2 and Mg in the presence of 10 mol-% of MgA
Figure 10. X-ray powder diffraction pattern of Mg3Bi2, prepared
from BiCl3 and Mg*; o, diffraction lines of Bi
Figure 13. X-ray powder diffraction pattern of MgHg, prepared
from HgCl2 and MgA
Figure 11. X-ray powder diffraction pattern of Mg3Sb2 (ϩ Sb),
prepared from SbCl3 and MgA; o, diffraction lines of Sb (after
annealing, 400°C)
Conclusion
to give a solid of composition Mg1.28Cd(MgCl2)0.02(CH2)1.9
Magnesium intermetallics with heavier group 12Ϫ15 met-
(Expt. 8.1) which exhibited strong X-ray powder diffraction als, which were previously known only in bulk form[8], can
lines for MgCd and a weak reflection for MgCd3[27] (Figure now be prepared in a highly active, nanocrystalline or
12). The formation of a mixture of MgϪCd intermetallics amorphous state using a wet-chemical method (Eqs. 1Ϫ3).
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up to room temperature over a period of 18 h to give a black sus-
pension. The Ga* was allowed to settle on the bottom of the flask
and the green- or yellow-coloured supernatant liquid was removed.
The solid was washed with several portions of fresh THF until the
supernatant liquid was colourless. The metal could also be isolated
by separating the reaction slurry using a centrifuge and, after wash-
ing, transferring the solid suspended in fresh THF, into a Schlenk
flask.
They have, through metathetical exchange reactions (Eqs.
13 and 14), a synthetic potential as reagents for inorganic
and organometallic chemistry, especially for the preparation
of bimetallic noble metalϪmain-group metal heterogeneous
catalysts[16][17][18][29][30]. In this sense, they represent main-
group metal counterparts of inorganic Grignard reagents[1]
(see Introduction). In addition, the low-temperature, kine-
tically controlled processes, such as for example in Eqs. 13
and 14, may be suitable for the preparation of as yet un-
known metastable systems.
Mg2Ga5 from Ga* and MgA: 3.67 g (8.7 mmol) of MgA was
transferred at room temperature to the Ga* suspension (see above)
in 100 ml of THF. The reaction mixture immediately turned green
(reaction of MgA with residual MgCl2 to form the radical anion
complex Mg2Cl3(THF)6ϩ AϪ • [34]). After stirring at room tempera-
ture for 24 h, the product was allowed to settle from the suspension
The authors thank Prof. Dr. C. Krüger, Dr. C. Lehmann, Dr. B.
Tesche, and their coworkers (Max-Planck-Institut für Kohlenfor-
schung) for conducting and discussing the XRD, DSC, TEM, and
EDX analyses, and Dr. J. S. Bradley for useful comments. Financial (now dark grey- or black-coloured), washed with several portions
support by the Fonds der Chemischen Industrie is gratefully
acknowledged.
of THF, and dried under high vacuum. 1.53 g (83%) of Mg2Ga5
was obtained as a crystalline, black pyrophoric powder. Only dif-
fraction lines corresponding to Mg2Ga5[7] were noted in the X-ray
powder diffraction pattern (Figure 1).
MgTl from TlCl and MgA ( Expt. 3.2) : Solid TlCl (1.18 g, 4.92
mmol) was added in small portions to a stirred suspension of MgA
(15.0 mmol) in THF (100 ml) at room temperature. From time to
time 1.0-ml samples were taken from the stirred suspension,
quenched with 3.0 ml of a toluene/CH3OH mixture (25:1 vol./vol.)
containing a known amount of n-C16H34 as an internal standard
and the content of A in quenched samples determined by GC. De-
pendence of the concentration of A in solution (mol A/mol Tl)
from the reaction time (h): 0.21(0.17), 0.43(1.0), 1.29(8), 1.37(24),
1.52(120).
Experimental Section
Instruments: X-ray diffraction patterns: STOE, STAD/2/PL pow-
der diffractometer, Cu-Kα1 radiation; the samples were filled into
glass capillaries. HREM images: field emission TEM, Hitachi HF
2000, 200 keV. DSC: DuPont 9900; four points temperature and
heat calibration method; heating rate, 10°C/min; Al crucible. EX-
AFS[31] spectra were recorded at station 9.2 at the SRS, Daresbury
using a Si(220) double-crystal monochromator (storage-ring con-
ditions: ca. 2.0 GeV, 150Ϫ200 mA). In all cases, data were collected
in transmission mode. For the measurements, the material was
mixed with PE and pressed to form self-supporting wafers. During
the experiments the samples were kept under argon. To eliminate
higher harmonics the second monochromator crystal was detuned,
reducing the intensity of the X-ray beam to 65% (Pd-K and Sn-K
absorption edges) or 50% (Pb-LIII, Cu-K absorption edges) of its
maximum value. During the experiments, the energy calibration of
the monochromator was checked with metal foils. Photoelectron
threshold energies of 24350 eV, 29202 eV, 13055eV, and 8981 eV
were chosen for the Pd-K, Sn-K, Pb-LIII and Cu-K absorption
edges, respectively. Data evaluation was performed in k space using
the program package[32] and amplitude and phase data calculated
with the program FEFF6[33]. The usable k ranges were 2.9Ϫ10.2
After 170 h, the black suspension was filtered, the precipitate
washed several times with THF (until the washing liquids become
colourless) and dried in vacuum. MgTl (0.95 g, 81%) was obtained
as a silvery shining powder. For the discussion of the DSC analysis
of MgTl, see the general section. The X-ray diffractogram of MgTl
is shown in Figure 2.
Sn* from SnCl2 and MgA at Room Temperature ( Expt. 4.1) : To
a cooled and stirred suspension of 6.45 g (15.4 mmol) of MgA in
50 ml of THF was added, in one portion, a solution of 3.21 g (16.9
mmol) of anh. SnCl2 in 50 ml of THF; the temperature of the
reaction mixture rose from 13 to 25°C and a black solid precipi-
tated. During the subsequent stirring of the reaction mixture at
room temperature, samples (2 ml) of the solution were taken, and
by complexometric titration it was determined that the deposition
of tin had already been completed after about 3 min. After this
time, upon the hydrolysis of an aliquot of the solution, a molar
ratio of A/9,10-dihydroanthracene (DHA) of 30:1 was determined
by GC. The suspension was filtered, the precipitate was washed
with THF and dried under vacuum. 1.34 g of a black powder was
obtained which had the composition and the specific surface area
as given in Table 4.
Ϫ1
Ϫ1
˚
˚
A
at the Cu-K edge, 2.4Ϫ14.3 A at the Sn-K edge, 2.8Ϫ12.2
at the Pb-LIII edge and 2.4Ϫ12.3 A at the Pd-K edge.
Ϫ1
Ϫ1
˚
˚
A
Analyses: Elemental analyses and AAS measurements: Dornis
and Kolbe, Mülheim an der Ruhr, Germany.
Materials: Magnesium anthracene·3 THF (MgA).[2] Mg powder
(270 mesh, PK-31), purchased from the Eckart-Werke, Fürth, Ger-
many, was used in all experiments unless otherwise stated. THF
was boiled for several hours over MgA[2] and subsequently distilled
under argon. All experiments and manipulations with air-sensitive
materials were performed under dry argon. Vacuum ϭ 0.1Ϫ0.2
mbar; high vacuum ϭ 10Ϫ3 mbar.
Sn* from SnCl2 and MgA at Low Temperatures ( Expt. 4.2) : A
cooled (ca. Ϫ30°C) solution of SnCl2 in THF was added to a
stirred suspension of MgA in THF which had been cooled to
Ϫ70°C. The suspension was allowed to warm up to room tempera-
ture (24 h) and thereafter stirred at room temperature for another
24 h. A small part of Sn* was isolated by filtration, washing with
THF and drying under vacuum. The Sn* thus obtained exhibited
in XRD only broad, diffuse diffraction lines for Sn.
Two-Step Preparation of Mg2Ga5. Ϫ Active Gallium ( Ga*) from
GaCl3 and MgA ( Expt. 3.1) : 13.0 g (31 mmol) of MgA was sus-
pended in 50 ml of THF. 50 ml of a 0.45  solution of GaCl3 in
THF (22.5 mmol; GaCl3 solutions in THF must be stored at Յ
Ϫ20°C, because at room temperature the solution eventually solidi-
fies due to cationic polymerisation of THF) was added over a per-
iod of 0.5 h into the stirred MgA suspension previously cooled to
Ϫ78°C. The colour of the suspension changed from orange to a
dark brownish black. The stirred suspension was allowed to warm
Preparation of the Sn*/Mg2Sn ϭ 1:1 Mixture from SnCl2 and
MgA and the Subsequent Reaction of the Mixture with SnCl2 to give
Sn* ( Expt. 4.3) : To a stirred solution/suspension of 6.94 g (16.6
1706
Eur. J. Inorg. Chem. 1998, 1699Ϫ1710

Magnesium Anthracene Systems, 10
Table 3. Mg2Ga5 and MgTl from MCln (M ϭ Ga, Tl) and MgA
FULL PAPER
MCln
[g]
MgA
MCln/MgA THF
molar
react. temp. [°C]/ solid
react. time [h]
[g]
elem. composition [ %] yield[a]
DSC XRD
Mg M Cl C H
expt. (mmol) [mmol] ratio
empirical formula
[%]
1
GaCl3
3.96
31.0
8.7
1:1.38
0:0.39
1:3
100
Ϫ78/0.5
Ϫ78 Ǟ r. t./18 not isolated
(22.5)
r. t./24
1.53
13.7 85.1 0.17 0.61 0.30 83
Mg2.31Ga5Cl0.02C0.2H1.2
n.d. Mg2Ga5
(Figure 1)
2
TlCl
1.18
(4.92)
15.0
100
r. t./170
0.95
9.0 85.8 0.15 0.91 0.19 81
Mg0.88TlCl0.01C0.2H0.5
see
MgTl
text (Figure 2)
[a] Based on M.
mmol) of MgA in 50 ml of THF was added dropwise a solution of
1.56 g (8.2 mmol) of anhydrous SnCl2 dissolved in 50 ml of THF
at room temperature over a period of 1 h, whereupon a black sus-
pension formed. After stirring at room temperature for 1 h, a 2-ml
The TEM photograph of Mg2Sn taken from the experiment is
reproduced in Figure 3; point-by-point EDX analyses of the nano-
crystals gave Mg/Sn ratios ranging between 1.7 and 2.7, the ma-
jority of analyses giving a value of 2.0. Traces of Cl but no free Mg
sample of the suspension was protolyzed with 2 ml of a mixture of or Sn could be identified by EDX. The results confirm the forma-
toluene/CH3OH, 25:1, (using n-C16H34 as an internal standard) and
analyzed by GC, whereafter the batch contained 15.4 mmol of an-
thracene and 0.3 mmol of 9,10-dihydroanthracene. Analysis of the
deep-blue THF solution by complexometry showed 9.4 mmol of
Mg2ϩ and 0.01 mmol of Sn. The suspension was filtered, and the
solid was washed with THF until the washing liquid was colourless.
After drying under vacuum, 1.17 g of black pyrophoric solid was
obtained which had the composition Mg 12.4, Sn 60.5, C 1.9, H
0.3% (Mg/Sn ϭ 1:1). After hydrolysis (H2O ϩ 5  H2SO4, 1:1) of
a sample of the solid and GC analysis of the organic portion, the
solid contained 0.03% of anthracene. According to the X-ray pow-
der analysis the solid was a mixture of Mg2Sn with elemental Sn.
tion of the intermetallic Mg2Sn.
Monitoring of the Reaction SnCl2 and MgA to form Mg2Sn at
0°C ( Expt. 4.5) : 32.1 mmol of MgA was suspended in 125 ml of
THF, the suspension was cooled to 0°C and kept at that tempera-
ture throughout the experiment by means of a cryostat. To the
stirred suspension were added 1.48 g (7.8 mmol) of solid SnCl2. 2.0
ml samples were taken periodically (see Figure 4) from the stirred
suspension, quenched with a standard solution (see Expt. 3.2) and
the content of A and DHA in the hydrolyzed samples with respect
to the standard were determined by GC analysis. Analogous experi-
ments were also carried out with equimolar amounts of SnF2,
SnBr2, and SnI2, and the same amounts of MgA and solvent. The
results are graphically represented in Figure 4.
The preparation of the 1:1 mixture of Mg2Sn ϩ Sn* was repeated
in the same manner as described above and was confirmed by X-
ray powder analysis of an isolated small sample of the solid. The
moist solid left after filtration was suspended in 50 ml of THF, the
stirred suspension was mixed with a solution of 8.2 mmol of SnCl2
in 47 ml of THF, and the mixture was stirred at room temperature
for 7 h. The suspension was filtered and the solid was washed with
THF and dried under vacuum. According to the X-ray diffractog-
ram, only Sn, with no Mg2Sn, was present in the solid.
The Two-step Preparation of Mg2Sn from SnCl2 and MgA ( Expt.
4.6) : A solution of 7.7 mmol of SnCl2 in 30 ml of THF was added
dropwise to a stirred suspension of 7.7 mmol of MgA in 100 ml of
THF. The black suspension of Sn* was stirred at room temperature
for 1 h. The suspension was then cooled down to 0°C and an ad-
ditional 24.5 mmol of MgA added. The progress of the stirred-
batch reaction at 0°C was monitored as described in Expt. 4.5 and
is represented graphically in Figure 4. The Mg2Sn thus prepared
was isolated and analyzed as described for Expt. 4.4; X-ray dif-
fractogram, see Figure 5.
Mg2Sn from SnCl2 and MgA ( Expt. 4.4) : 35 ml of a 0.217 
solution of SnCl2 in THF (7.6 mmol) was added dropwise within
15 min to a stirred suspension of 12.82 g (30.6 mmol) of MgA in
100 ml of THF. (Solutions of SnCl2 in THF are stable at room
temperature for only ca. 15 min, but can be stored for long periods
of time at Ϫ20°C.) The colour of the suspension changed from
orange to olive green-black during the slightly exothermic reaction.
After stirring for 3 h, the suspension was filtered (D4 sinter) and
the solid washed with ca. 100-ml aliquots of THF. The filtrate was
yellow-green (unreacted MgA) and at the final washing colourless.
GC analysis of the combined filtrate showed 25.5 mmol of A and
3.4 mmol of DHA to be present. The black solid was dried under
vacuum. Mg2Sn (1.39 g, 87%) was obtained as a crystalline, black
pyrophoric powder with the composition and the specific surface
area as given in Table 4. A DSC analysis of a sample of Mg2Sn
thus prepared showed no endothermic peak up to 300°C (con-
firming the absence of Sn, m.p. 231.97°C, or of a SnϪMg2Sn eutec-
tic, m.p. 203.5°C), but a weakly exothermic peak at 219°C. An X-
ray diffractogram of a sample of Mg2Sn was in accordance with
Mg2Sn from SnCl2 and MgA at Low Temperature ( Expts. 4.7 and
4.8) : The experiments were conducted in an analogous manner to
Expt. 4.4, except that SnCl2 was added to MgA each time at Ϫ70°C
and, thereafter, the temperature of the reaction mixtures slowly
raised from Ϫ70°C to room temperature (see Table 4). The Mg2Sn
thus prepared (Expt. 4.7) exhibited in the X-ray diffractogram only
broad diffuse reflections characteristic of the intermetallic and Sn.
The Mg2Sn prepared in Expt. 4.8 was used for the reaction with
CuCl2 to form a CuϪSn alloy (see Expt. 6.1).
Mg2Pb from PbCl2 and MgA at Low Temperatures ( Expt. 5.1) :
The experiment was conducted in the same manner as Expts. 4.7
and 4.8. The XRD powder pattern of the reaction product was
consistent with Mg2Pb, except for very weak reflections for Pb;
Mg2Pb thus prepared was used for the reaction with PdCl2 to form
a PdϪPb alloy (Expt. 6.2).
Mg2Pb from PbCl2, Mg Powder and 10 mol-% of MgA ( Expt.
5.2) : A suspension of 1.69 g (6.1 mmol) of PbCl2, 19.1 mmol of
the line diagram of Mg2Sn from ref.[35]
.
Eur. J. Inorg. Chem. 1998, 1699Ϫ1710
1707

´
B. Bogdanovic et al.
FULL PAPER
Table 4. Sn* and Mg2Sn from SnCl2 and MgA
SnCl2
[g]
MgA
SnCl2/MgA THF
molar
react. temp. [°C]/ solid
react. time [h]
[g]
elem. composition [ %] yield[a]
sp. surf. XRD
area
Mg Sn Cl C H
[%]
expt. (mmol) [mmol] ratio
empirical formula
[m2gϪ1
16.2
nd
]
1
2
3
4
5
6
3.21
(16.9)
15.4
40.0
16.6
30.6
32.1
1:0.9
1:0.92
1:2
100
280
100
135
125
130
r. t./2
1.34
1.2 96.8 0.35 nd
Mg0.06SnCl0.01
65
nd
Sn
8.20
(43.3)
Ϫ70 Ǟ r. t./24 0.94[b]
r. t. / 24
0.57 97.9 0.74 0.44 0.1 nd
Mg0.03SnCl0.02C0.04H0.1
1.56
(8.2)
r. t./1
r. t./3
0/48
1.17
1.39
1.21
12.4 60.5 nd 1.9 0.3
73
87
81
nd
Mg2Sn[c]
ϩ Sn
MgSnCl0.3H0.6
1.44
(7.6)
1:4
26.8 61.8 1.3 8.8 1.1
Mg2.1SnCl0.07C1.4H2.0
72.8
70.3
Mg2Sn[d]
1.48
(7.8)
1:4.1
25.4 62.0 1.5 9.4 1.4
Mg2SnCl0.08C1.5H2.7
Mg2Sn[e]
(ϩ Sn)
1.44
(7.6)
7.7
1:1
r. t./1
0/122
24.5
0:3.2
1.21
27.8 63.6 0.75 2.3 0.6 81
Mg2.13SnCl0.04C0.4H1.0
85.5
54.8
Mg2Sn[e][f]
7
8
5.31
(28.0)
97.3
45.4
1:3.5
1:3.5
300
220
Ϫ70 Ǟ Ϫ40/2 5.32
Ϫ40 Ǟ r. t./22
[g]
22.4 59.1 2.1 9.3 1.4
Mg1.85SnCl0.1C1.6H2.8
95
2.49
(13.1)
Ϫ70 Ǟ r. t./6
r. t./96
[a] Based on Sn. Ϫ [b] Only a small fraction of the solid was isolated. Ϫ [c] Reaction with SnCl2 to give Sn, see text. Ϫ [d] TEM photograph,
[e]
[f]
[g]
see Figure 3. Ϫ Progession of the reaction with time, see Figure 4. Ϫ XRD in Figure 5. Ϫ
Not isolated; used for the reaction
with CuCl2 (Expt. 6.1).
Mg powder and 1.9 mmol of MgA in 200 ml of THF was stirred
A Cu( Mg) Sn Alloy from Mg2Sn and CuCl2 ( Expt. 6.1) : The
for 10 days at 0°C. During the first 24 h of reaction the total Mg2Sn suspension in THF (Expt. 4.8) was allowed to settle, the
amount of Mg2ϩ analyzed in the THF solution increased to 7.3
mmol and, thereafter, remained constant. Hydrolysis of an aliquot
of the THF solution gave 1.5 mmol of n-butanol, expressed in
terms of the whole solution (GC analysis) Ϫ the product of THF
cleavage by Mg[23a]. Mg2Pb was isolated from the THF solution in
the same way as described in Expt. 4.4. XRD powder pattern in
Figure 6.
green supernatant solution was syphoned off, 50 ml of THF was
added to the Mg2Sn, the resulting suspension was stirred for 30
min, and the solution was again syphoned off. This operation was
repeated two more times. Then, Mg2Sn was suspended in 100 ml
of fresh THF, the suspension was mixed with 3.48 g (25.9 mmol)
of anhydrous CuCl2 and was stirred at room temperature for 65 h.
The black suspension was filtered, the solid was washed 4 or 5
Table 5. Mg2Pb from PbCl2 and MgA or Mg powder and 10 mol-% of MgA
PbCl2
[g]
MgA or
Pb/Mg
THF
react. temp. [°C]/
react. time [h]
solid
[g]
elem. composition [ %] yield[a]
Mg Pb Cl C H
empirical formula
sp. surf. XRD
area
Mg ϩ MgA ratio
expt. (mmol) [mmol]
[%]
92
[m2gϪ1
10.7
nd
]
1
2
4.84
(17.4)
MgA
64.7
1:3.7
1:3.5
300
200
Ϫ78 Ǟ r. t./24
r. t./72
0/260[c]
4.70
1.56
15.3 70.7 1.0 4.5 0.6
Mg1.84PbCl0.08C1.1H1.8
Mg2Pb[b]
(ϩ Pb)
Mg2Pb[d]
(ϩ Pb)
1.69
(6.1)
Mg 19.1
ϩ MgA 1.9
15.6 71.6 0.98 3.3 0.5 90
Mg1.86PbCl0.08C0.8H1.4
[a]
[b]
Based on Pb. Ϫ
Used for the reaction with PdCl2 (Expt. 6.2). Ϫ According to the amount of Mg2ϩ in the THF solution, the
[c]
reaction was complete after ca. 20 h. Ϫ [d] XRD powder pattern in Figure 6.
Table 6. CuϪSn and PdϪPb alloys from Mg2Sn, Mg2Pb and the respective metal chlorides (MЈCl2)
Mg2M
[g]
MЈCl2
Mg2M:
THF
react. time[a] solid
elem. composition [ %] yield[b]
MЈ Mg M Cl C H
sp. surf. XRD
area
MЈCl2
expt. (mmol) (mmol) molar ratio [ml]
[h]
65
[g]
empirical formula
[%]
[m2gϪ1
]
1
2
Mg2Sn
(13.1)
CuCl2
(25.9)
1:2
150
30
3.23
0.99
41.5 2.4 47.6 1.9 3.6 0.5 99
Cu1.64Mg0.25SnCl0.13C0.4H1.2
31.2
Cu6Sn5
ϩ Cu3Sn[c]
Mg2Pb
(2.14)
PdCl2
(4.8)
1:2.2
170
44.4 0.6 45.4 2.4 1.4 0.3 100
Pd1.90Mg0.12PbCl0.31C0.9H1.4
18.9
Pd3Pb
ϩPd3Pb2
[c]
[a] Room temperature. Ϫ [b] Based on M. Ϫ [c] After heating the sample to 400°C.
1708
Eur. J. Inorg. Chem. 1998, 1699Ϫ1710

Magnesium Anthracene Systems, 10
FULL PAPER
times with THF and was dried under high vacuum, yielding 3.23
g of an Mg-containing CuϪSn alloy which had the composition
shown in Table 6. The EXAFS spectra of the Cu(Mg)Sn alloy are
shown in Figure 7 and discussed in the text. In the filtrate of the
batch were found 20.6 mmol of Mg2ϩ by way of an analysis (79%).
Mg3Bi2 from BiCl3 and Mg* ( Expt. 7.2) : The experiment was
conducted in the same manner as in Expt. 7.1. XRD powder pat-
tern in Figure 10.
( Mg3Sb2 ϩ Sb) from SbCl3 and MgA ( Expt. 7.3) : SbCl3 was
added to the stirred suspension of MgA in THF. The reaction mix-
A Pd( Mg) Pb Alloy from Mg2Pb and PdCl2 ( Expt. 6.2) : 0.85 g ture was stirred for several days at room temperature. The solid
(4.8 mmol) of anhydrous PdCl2 was added to a stirred suspension was isolated in the same manner as described in Expt. 7.1. After a
of 0.63 g of Mg2Pb from Expt. 5.1 (2.14 mmoles Pb) in 30 ml of hydrolytic work-up of the solid, THF and anthracene were ident-
THF. The suspension was stirred for 7 d at room temperature, fil-
tered and the resulting solid washed with THF and dried under
high vacuum. Yield: 0.99 g of a black powder of the composition
as given in Table 6. The EXAFS spectra of the Pd(Mg)Pb alloy are
shown in Figure 8 and discussed in the text. Mg2ϩ content of the
filtrate: 4.1 mmol.
ified in the organic phase by mass spectrometry.
MgCd( ϩ MgCd3) from CdCl2, Mg Powder and a Catalytic
Amount of MgA ( Expt. 8.1) : A mixture of 1.33 g (7.24 mmol) of
anhydrous CdCl2 and 0.38 g (15.8 mmol) of Mg powder in 100 ml
of THF was stirred at room temperature for 72 h; during this time,
no reaction took place between CdCl2 and Mg, as shown by the
absence of any MgCl2 in the THF solution. After addition of 1.0
mmol of MgA, the mixture was stirred for an additional 48 h, after
which 11.0 mmol of Mg in the form of MgCl2 (65.4% of the total
amount of Mg used) was determined by complexometry in the
solution (Cdϩ2 ions were masked by addition of KCN). After
Mg3As2 from AsCl3 and Mg* ( Expt. 7.1) : 9.21 g (22.2 mmoles)
of MgA was suspended in 400 ml of toluene and stirred at room
temperature for 24 h yielding a fine grey suspension of Mg*. Most
of the solvent toluene was removed by decanting leaving ca. 40 ml
of toluene with Mg*. After adding 100 ml of THF and 1.30 g (7.15
mmol) of AsCl3 to Mg*/THF suspension, the reaction mixture was further stirring for several days, the concentration of MgCl2 in the
stirred for 5 d at room temperature. After filtration, washing with
THF and pentane, and drying under vacuum, 0.95 g of Mg3As2
was obtained as a deep brown pyrophoric powder. XRD powder
pattern in Figure 9.
THF solution remained almost unchanged. Filtration, washing
with THF and drying under high vacuum yielded 0.91 g of a grey
powder with the composition given in Table 8. The X-ray pattern
of the powder (Figure 12) exhibited, in addition to one weak signal
Table 7. Mg3M2 (M ϭ As, Sb, Bi) Zintl phases from MCl3 and Mg*, Mg powder or MgA
MCl3
[g]
M*(Mg)
or MgA
MCl3/Mg THF
molar
ratio
reaction[a] solid
elem. composition [ %]
yield[b]
[%]
sp. surf. XRD
time
[h]
Mg M Cl C H
area
expt. (mmol) [mmol]
[ml]
100
[g]
empirical formula
[m2gϪ1
]
[c][d]
1
AsCl3
1.30
(7.15)
Mg*
22.2
1:3.1
1:3.2
1:3.1
1:3.2
120
72
0.95
27.2 55.3 3.3 6.7 1.3
Mg1.51AsCl0.12C0.8H1.8
98
167.7
55.3
Mg3As2
(ϩ MgO)
1a
2
AsCl3
Mg
19.8
50
0.66
1.80
1.29
29.7 60.8 2.3 1.6 0.4
Mg1.50AsCl0.08C0.2H0.5
Mg3As2
(ϩ Mg
As)[e]
ϩ
BiCl3
2.25
(7.14)
Mg*
100
160
48
14.1 80.2 1.5 3.5 0.6
Mg1.51BiCl0.11C0.8H1.5
97
67.9
Mg3Bi2
(ϩ Bi)[f]
22.3
3
SbCl3
1.55
(6.78)
MgA
290
19.4 64.3 1.2 8.9 1.5
Mg1.51SbCl0.06C1.4H2.8
100
153.9
Mg3Sb2
ϩ Sb[g]
21.7
[a] Room temperature. Ϫ [b] With respect to M. Ϫ [c] After 24 h at 400°C. Ϫ [d] XRD in Figure 9. Ϫ [e] After heating the sample to 400°C
for 24 h, X-ray diffractogram shows only Mg3As2. Ϫ [f] Untempered sample; XRD in Figure 10. Ϫ [g] After the sample had been heated
to 400°C for 24 h; XRD in Figure 11.
Table 8. MgϪCd and MgϪHg intermetallics from the corresponding metal chlorides and Mg powder in the presence of MgA, or MgA
MCl2
[g]
Mg ϩ MgA MCl2/Mg
THF
[ml]
react. time[a] solid
elem. composition [ %] yield[b]
sp. surf. XRD
area
or MgA
molar ratio
1:2.2
Mg M Cl C H
Expt. (mmol) (mmol)
[h]
72
[g]
empirical formula
[%]
[m2gϪ1
]
1
CdCl2
(1.33)
Mg (15.8)
ϩMgA (1.0)
100
0.91
17.4 62.4 0.5 12.9 2.3 70
Mg1.29CdCl0.03C1.94H1.19
nd
MgCd[c]
(ϩ
MgCd3)
(Figure
12)
(7.24)
2
HgCl2
1.06
MgA
(14.9)
1:3.8
40
120
0.82
12.1 75.8 0.1 6.0 0.6
79
12.1
MgHg[c]
(Figure
13)
Mg1.32HgCl0.01C1.32H1.65
(3.9)
[a] At room temperature. Ϫ [b] With respect to M. Ϫ [c] Untempered sample.
Eur. J. Inorg. Chem. 1998, 1699Ϫ1710
1709

´
B. Bogdanovic et al.
FULL PAPER
[5e]
1684; Angew. Chem., Int. Ed. Engl. 1993, 32, 1646. Ϫ
Sauthoff, Intermetallics, VCH, Weinheim, 1995.
G.
for MgCd3, strong reflections for MgCd. 30 ml of the total 171 ml
of the THF solution was evaporated to dryness under vacuum,
giving 0.675 g of a solid (5.1 wt.-% Cd; 1.73 mmol of Cd).
[6] [6a]
G. S. Smith, Q. Johnson, D. H. Wood, Acta Crystallogr.
1969, B25, 554. Ϫ [6b] A. A. Nayeb-Hashemi, J. B. Clark, Bull.
Alloy Phase Diagr. 1985, 6, 434. Ϫ [6c] P. Feschotte, K. Yvon, J.
Less-Common Met. 1990, 158, 89. Ϫ [6d] M. Notin, E. Belbacha,
MgHg from HgCl2 and MgA ( Expt. 8.2) : 1.06 g (3.9 mmol) of
HgCl2 was added to a stirred suspension of 6.24 g (14.9 mmol) of
MgA in 40 ml of THF. After 10 min of stirring, a 1.0 ml sample
was taken from the stirred suspension, quenched with 5.0 ml of the
standard solution (Expt. 3.2) and analyzed by gas chromatography.
Found: 2 A/Hg. (After stirring for a further 120 h, the amount of
A increased to 2.5 A/Hg.) Isolation of MgHg was carried out as
described above for MgCd. XRD powder pattern (nontempered)
in Figure 13.
[6e]
J. Charles, J. Hertz, J. Alloys Comp. 1991, 176, 25. Ϫ
T. B.
Massalski, J. G. Murray, L. H. Bennett, H. Baker, Binary Alloy
Phase Diagrams, American Society for Metals, Metals Park,
Ohio, 1st printing, 1986, vol. 1 and 2, p. 1142Ϫ1143.
PDF-2, ICCD, International Center for Diffraction Data, New-
ton Square, PE, USA, 1993, [25Ϫ227].
H. Schäfer, B. Eisenmann, W. Müller, Angew. Chem. 1973, 85,
742; Angew. Chem., Int. Ed. Engl. 1973, 12, 694.
W. Hume-Rothery, G. V. Raynor, J. Inst. Met. 1938, 63, 201.
Ref.[6e], p. 1556.
[7]
[8]
[9]
[10]
[11]
Ref.[7], [3Ϫ846].
[12] [12a] G. Bauer, J. Tiesler, Z. Anorg. Allg. Chem. 1950, 262, 319. Ϫ
[12b] G. H. Grosch, K.-J. Range, J. Alloys Comp. 1996, 235, 250.
[1] [1a]
[13]
´
´
L. E. Aleandri, B. Bogdanovic, P. Bons, Ch. Dürr, A. Gaid-
B. Bogdanovic, Acc. Chem. Res. 1988, 21, 261.
[14]
[15]
ies, Th. Hartwig, S. C. Huckett, M. Lagarden, U. Wilczok, R.
Ref.[6e], p. 964Ϫ5.
[1b]
Ref.[6e], p. 1831Ϫ34.
´
B. Bogdanovic,
A. Brand, Chem. Mater. 1995, 7, 1153. Ϫ
[16] [16a]
U. Wilczok (Studiengesellschaft Kohle mbH), Europ. Pat. Appl.
H. Bönnemann, W. Brijoux, K. Siepen, J. Hormes, R.
Franke, J. Pollman, J. Rothe, Appl. Organomet. Chem., in press.
[1c]
0469463, 1992; Chem. Abstr. 1993, 118, 24647x. Ϫ
L. E.
[16b] K. Siepen, Dissertation, RWTH Aachen, 1996.
´
Aleandri, B. Bogdanovic, A. Gaidies, D. J. Jones, S. Liao, A.
Ϫ
[17]
[18]
[19]
[20]
[21]
[22]
`
Michalowicz, J. Roziere, A. Schott, J. Organomet. Chem. 1993,
J. G. Ulan, E. Kuo, W. F. Maier, J. Org. Chem. 1987, 52, 3126.
R. Ohnishi, I. Suzuki, M. Ichikawa, Chem. Lett. 1991, 841.
Ref.[7], [2Ϫ717].
[1d]
´
L. E. Aleandri, B. Bogdanovic, Ch. Dürr, S. C.
459, 87. Ϫ
`
Huckett, D. J. Jones, U. Kolb, M. Lagarden, J. Roziere, U. Wil-
czok, Chem. Eur. J. 1997, 3, 1710. Reviews: Ϫ [1e] L. E. Alean-
Ref.[7], [20Ϫ827].
´
`
dri, B. Bogdanovic, Ch. Dürr, D. J. Jones, J. Roziere, U. Wil-
E. Zintl, E. Husemann, Z. Phys. Chem. 1933, B 21, 138.
E. Zintl, Z. Elektrochem. 1934, 40, 142.
[1f]
czok, Adv. Mater. 1996, 8, 600. Ϫ
L. E. Aleandri, B. Bog-
[23] [23a]
´
´
E. Bartmann, B. Bogdanovic, N. Janke, S. Liao, K.
danovic in Active Metals (Ed: A. Fürstner), VCH, Weinheim,
1996, chapter 8.
Schlichte, B. Spliethoff, J. Treber, U. Westeppe, U. Wilczok,
[2] [2a]
[23b]
´
B. Bogdanovic, S. Liao, K. Schlichte, U. Westeppe in Syn-
Chem. Ber. 1990, 123, 1517. Ϫ
E. Bartmann, B. Bog-
´
thetic Methods of Organometallic and Inorganic Chemistry (Ed:
danovic, N. Janke, S. Liao, K. Schlichte, B. Spliethoff, J. Treber,
U. Westeppe, U. Wilczok in Synthetic Methods of Organometal-
lic and Inorganic Chemistry (Ed.: W.A. Herrmann), Thieme Ver-
lag, Stuttgart, 1996, vol. 1, p. 39.
Ref.[7], [4Ϫ458].
W.A. Herrmann), vol. 1, p. 47, Thieme Verlag, Stuttgart, 1996.
[2b]
´
B. Bogdanovic, S. Liao, K. Schlichte, U. Westeppe in Or-
Ϫ
ganometallic Syntheses (Eds: R. B. King, J. J. Eisch), Elsevier,
Amsterdam, 1988, vol. 4, p. 410. Ϫ
[2c]
[24]
[25]
[26]
[27]
[28]
[29]
´
B. Bogdanovic, S. Liao,
R. Mynott, K. Schlichte, U. Westeppe, Chem. Ber. 1984, 117,
1378.
Ref.[7], [4Ϫ464].
Ref.[7], [29Ϫ131].
[3]
Ordinary Mg powder in the presence of catalytic amounts of
MgA (or anthracene) has been applied as a reducing agent in
the preparation of finely divided homometallic powders and
Ref.[7], MgCd [8Ϫ389], MgCd3 [29-264].
Ref.[7], [20Ϫ319].
R. Ohnishi, W.-G. Wang, M. Ichikawa, Appl. Catal. A 1994,
113, 29.
transition metal complexes: [3a] H. Bönnemann, B. Bogdanovic,
´
[30] [30a]
R. Brinkmann, D.-W. He, B. Spliethoff, Angew. Chem. 1983,
O. A. Feretti, C. Lucas, J. P. Candy, J. -M. Basset, B. Di-
[3b]
95, 749; Angew. Chem., Int. Ed. Engl. 1983, 22, 728. Ϫ
H.
dillon, F. LePeltier, J. Mol. Catal. A 1995, 103, 125 and refer-
ences therein. Ϫ [30b] J. Toyir, M. Leconte, G. P. Niccolai, J. -P.
Candy, J. -M. Basset, J. Mol. Catal. A 1995, 100, 61. Ϫ [30c] K.
Yoshikawa, Y. Iwasawa, J. Mol. Catal. A 1995, 100, 115.
H. Bertagnolli, T. S. Ertel, Angew. Chem. 1994, 106, 15; Angew.
Chem., Int. Ed. Engl. 1994, 33, 45.
´
Bönnemann, B. Bogdanovic, R. Brinkmann, B. Spliethoff, D.-
W. He, J. Organomet. Chem. 1993, 451, 23; see also ref.[1f]
.
´
[4]
Preliminary communication: L. E. Aleandri, B. Bogdanovic, M.
[31]
[32]
Lagarden, K. Schlichte, Abstracts of Papers, 24. GDCh-
Hauptversammlung, Hamburg, 5Ϫ11 September 1993, Ab-
stract AC, 173, VCH, Hamburg, 1993; see also ref.[1f] and B.
T. S. Ertel, H. Bertagnolli, S. Hückmann, U. Kolb, D. Peter,
´
Bogdanovic, K. Schlichte in Synthetic Methods of Organometal-
Appl. Spectrosc. 1992, 46, 690.
lic and Inorganic Chemistry (Ed.: W.A. Herrmann), Thieme Ver- [33] [33a] J. J. Rehr, R. C. Albers, Phys. Rev. 1990, B 41, 8139. Ϫ
[33b]
lag, Stuttgart, 1996, vol.1, p. 49.
J. J. Rehr, J. Mustre de Leon, S. I. Zabinsky, R. C. Albers, J.
[5]
[33c]
In recent years, there has been an increasing activity with regard
to the synthesis and investigation of intermetallic compounds,
especially of Zintl phases and ions: [5a] S. M. Kauzlarich (Ed.),
Chemistry, Structure and Bonding of Zintl Phases and Ions, VCH
Publishers, Inc., New York, 1996. Ϫ [5b] B. Eisenmann, Angew.
Am. Chem. Soc. 1991, 113, 5135. Ϫ
J. Mustre de Leon, J.
J. Rehr, S. I. Zabinsky, R. C. Albers, Phys. Rev. 1991, B 44,
4146. Ϫ [33d] J. J. Rehr, S. I. Zabinsky, R. C. Albers, Phys. Rev.
Lett. 1992, 69, 3397.
[34]
[35]
´
B. Bogdanovic, N. Janke, C. Krüger, R. Mynott, K. Schlichte,
U. Westeppe, Angew. Chem. 1985, 97, 972; Angew. Chem., Int.
Ed. Engl. 1985, 24, 960.
Ref.[7], [7-274].
[98104]
Chem. 1993, 105, 1764; Angew. Chem., Int. Ed. Engl. 1993, 32,
[5c]
1693. Ϫ
R. Nesper, Angew. Chem. 1991, 103, 805; Angew.
Chem., Int. Ed. Engl. 1991, 30, 789. Ϫ [5d] C. J. Warren, D. M.
Ho, R. C. Haushalter, A. B. Bocarsly, Angew. Chem. 1993, 105,
1710
Eur. J. Inorg. Chem. 1998, 1699Ϫ1710