The trichlorogermanite(II) anion and its gold(I) complexes

Article abstract of DOI:10.1515/znb-1998-0902

Tetraphenylphosphonium trichlorogermanite(II) (1) has been prepared (as a reference compound) from Ph₄P⁺ Cl^- and GeCl₂(dioxane) in tetrahydronaphthalene. Its structure has been determined by single crystal X-ray methods. The lattice contains independent monomeric GeCl₃^- anions (Ge-Cl distances between 2.290 and 2.320 A, Cl-Ge-Cl angles between 95.33 and 98.27°). Treatment of (Ph₃As)AuCl with GeCl₂(dioxane) affords (Ph₃As)AuGeCl₃ in high yields as a germylene insertion product (2). The complex is a dimer in ihe crystal with a short Au--Au contact of 2.9415(4) A and bent As-Au-Ge axes [169.353(13)°]. The GeCl₃ ligand has shorter Ge-Cl bonds [2.175 to 2.183 A] and wider Cl-Ge-Cl angles than in the free anion [100.9 to 101.9°]. The analogous reaction with CH₂(AsPh₂AuCl)₂ leads only to a mono-insertion product in the form of a salt with {[CH₂(AsPh₂)₂Au]}₂²⁺ dications and two [ClAuGeCl₃]^- anions (3). In the lattice these three ions form a centrosymmetrical tetranuclear unit through short Au--Au contacts. The resulting z-shaped Au--Au--Au--Au chain has distances of 3.0499(6) (twice) and 3.1613(8) A and angles of 118.833(8)° (twice). The geometry of the GeCl₃ units is similar to that in 2. {(Et₃N)Au[P(o-Tol)₃]}⁺ PF₆^- (4) was obtained as a by-product in several reactions with the bulky phosphine and where NEt₃ was used as a base. The crystals contain two crystallographically independent cations with a similar core structure, but different conformations of the substituents. Both the P-Au and the N-Au bonds are elongated owing to steric effects.

Full text of DOI:10.1515/znb-1998-0902

The Trichlorogermanite(II) Anion and its Gold(I) Complexes
Upendra M. Tripathi, Gerald L. Wegner, Annette Schier, Alexander Jockisch,
Hubert Schmidbaur*
Anorganisch-chemisches Institut der Technischen Universität München,
Lichtenbergstrasse 4, D-85747 Garching, Germany
Z. Naturforsch. 53 b, 939-945 (1998); received June 25, 1998
Germanium(II), Trichlorogermanite(II), Gold-Germanium Compounds, Arsine Complexes,
Germylene Insertion
Tetraphenylphosphonium trichlorogermanite(II) (1) has been prepared (as a reference com-
pound) from PI14P Cl- and GeC^dioxane) in tetrahydronaphthalene. Its structure has been
determined by single crystal X-ray methods. The lattice contains independent monomeric
GeCh- anions (Ge-Cl distances between 2.290 and 2.320 A, Cl-Ge-Cl angles between 95.33
and 98.27°). Treatment of (Ph3As)AuCl with GeC^dioxane) affords (Ph;?As)AuGeCl3 in high
yields as a germylene insertion product (2). The complex is a dimer in the crystal with a short
Au--Au contact of 2.9415(4) A and bent As-Au-Ge axes [169.353(13)°]. The GeCb ligand has
shorter Ge-Cl bonds [2.175 to 2.183 A] and wider Cl-Ge-Cl angles than in the free anion [100.9
to 101.9°]. The analogous reaction with CH2(AsPh2AuCl)2 leads only to a mono-insertion
product in the form of a salt with {[CH2(AsPh2)2Au]}22+ dications and two [ClAuGeCb]- an-
ions (3). In the lattice these three ions form a centrosymmetrical tetranuclear unit through short
Au--Au contacts. The resulting z-shaped Au--Au--Au--Au chain has distances of 3.0499(6)
(twice) and 3.1613(8) Ä and angles of 118.833(8)° (twice). The geometry of the GeCb units is
similar to that in 2. {(Et3N)Au[P(o-Tol)3]}+ PFö~ (4) was obtained as a by-product in several
reactions with the bulky phosphine and where NEt3 was used as a base. The crystals contain
two crystallographically independent cations with a similar core structure, but different con-
formations of the substituents. Both the P-Au and the N-Au bonds are elongated owing to
steric effects.
Introduction
Results and Discussion
The trichlorogermanite(II) anion [GeC^]- is iso-
electronic with arsenic(III) chloride [ASCI3] and
can act as a soft donor ligand for low-valent, late
In the course of the present study we have
discovered another example of “free” [GeCl?]-
in the form of its tetraphenylphosphonium salt,
transition metals. The structures of the two species which was prepared in order to provide new
are expected to be very similar both as a free an- reagents for the introduction of the trichloroger-
ion/molecule and in analogous complexes. Struc- manite(II) ligand into coinage metal complexes.
tural studies of trichlorogermanate(II) salts are few Following earlier work [2,3] on prototypes
in number, and most of the examples reported in the like Ph3P-Au-GeCl3, we have also included a
literature feature aggregates {[GeC^],,}"- , as e. g. case where Pl^P is replaced by Pl^As in
in the classical case of CstGeC^]. It was only in order to match the isoelectronic combination
the lattice of salts with large cations, as in the ben- (AsX3/GeX3_ ). Following the same line, a polynu-
zyl(triethyl)ammonium salt, that isolated [GeC^]-
clear complex of bis(diphenylarsmo)methane
anions could be investigated, and in fact very close Ph2AsCH2AsPh2 (dpam) has also been prepared,
structural analogies between [GeC^]- and ASCI3
have been confirmed [1].
which was anticipated to complement the data on
the bis(diphenyl/
7/20j'/?/zmo)methane PhbPC ^PPl^
(dppm) [3 - 5]. A novel stoichiometry and structure
involving the anion [Cl-Au-GeC^]- was found,
however, which illustrates the diversity of structural
principles in this system.
* Reprint requests to Prof. Dr. H. Schmidbaur.
0932-0776/98/0900-0939 $ 06.00 © 1998 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
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940
U. M. Tripathi et al. • The Trichlorogermanite(II) Anion and its Gold(I) Complexes
The influence of a typical hard donor as com- other, with all C1---C1 and Cl---Ge contacts ex-
pared to the soft arsine and germanite(II) ligands ceeding 4.774 A. The anion has no crystallograph-
was briefly investigated by a study of the cationic
ically imposed symmetry, but the geometry closely
complex [(o-Tol)3P-Au-NEt3]+ obtained as a by- approaches the requirements of a threefold axis,
with Ge-Cl distances of 2.2900(8), 2.3030(8) and
2.3201(8) A, and Cl-Ge-Cl angles of 95.33(3),
95.38(3) and 98.27(3)° (Fig. 1). These parameters
resemble those reported for other known examples
with free [GeC^]- anions [1]. There is also a close
relation to the structural data of ASCI3 (in both the
gas phase and in the crystal lattice) and of [SeCl3]+,
following the isoelectronic principle [1].
product in a different context [6].
Tetraphenylphosphonium trichlorogerm anite(ll) (1)
The reaction of equivalent quantities of
tetraphenylphosphonium chloride and dichloroger-
manium(II)(dioxane) in tetrahydronaphthalene at
90°C leads to a virtually quantitative conversion of
the components into the 1:1 complex (99% yield,
m.p. 186°C) as a colourless crystalline salt. The
product can be recrystallized from dichloromethane
to give triclinic single crystals, space group Pi, con-
taining two formula units in the unit cell.
(Triphenylarsine)gold(I) trichlorogermanite(II) (2)
Treatment of (triphenylarsine)gold(I) chloride
with equimolar quantities of dichlorogerma-
nium(II)(dioxane) in tetrahydrofuran at room tem-
perature and under reflux conditions gives high
yields (90%) of the expected 1:1 complex as a
colourless, crystalline compound (m. p.l83°C).
[Ph4P]+Cl~ + GeCl2(dioxane)
—>dioxane + [Ph4P]+GeCl3_
The lattice contains no solvent molecules and
is composed of independent [Ph4P]+ cations and
[GeC^]- anions. The cation has a standard molec-
ular geometry which deserves no further comment
in this context. The individual [Ph4P]+ units are
stacked in columns with no sub-van der Waals
contacts.
(Ph3As)AuCl + GeCh (dioxane)
—>dioxane + (Ph3As)AuGeCl3
The crystals are monoclinic, space group C2/c, with
four formula units in the unit cell. The compound
is hence isomorphous with the triphenylphosphine
analogue [2]. In the lattice the molecules are ar-
In the parallel strings of [GeCf}]- anions the in-
dividual units are also well separated from each ranged in pairs with the monomeric units cross-
ing their principal molecular axes and with a re-
C43
markably short intermolecular Au--Au contact of
2.9415(4) A (Fig. 2). The arsine ligand has a stan-
dard molecular geometry which is not discussed any
further.
The trichlorogermanite(II) ligand shows signifi-
cant deviations from the geometry of the free an-
ion (above). All three Ge-Cl distances are short-
ened very considerably upon complexation [to val-
ues of 2.1750(10), 2.1782(10) and 2.1829(10) A],
and the angles Cl-Ge-Cl are widened to 100.91(4),
100.97(4) and 101.90(4)°. In the gold(I) complex
the structure is thus closer to the tetrahedral geo-
metry of regular four-coordinate germanium, and its
C34
Ge-Cl bond lengths indicate a significant strength-
Fig. 1. Molecular structure of compound 1 (ORTEP draw-
ing with 50% probability ellipsoids,oH-atoms omitted
for clarity). Selected bond lengths [A] and angles [°]:
Ge-Cll 2.3201(8). Ge-C12 2.2900(8), Ge-C13 2.3030(8),
P-Cll 1.786(2), P-C21 1.794(2), P-C31 1.789(2), P-C41
1.792(2); Cll-Ge-C12 95.38(3), Cll-Ge-C13 95.33(3),
C12-Ge-C13 98.27(3).
ening through the concomitant rehybridization of
the germanium atom.
The axis Ge-Au-As is strongly bent away from
linearity [bond angle 169.353(13)°] which facili-
tates the intermolecular approach and the aurophilic
Au--Au contact. In this respect the situation is
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U. M. Tripathi et al. • The Trichlorogermanite(II) Anion and its Gold(I) Complexes
Fig. 3. Molecular structure of compound 3 (ORTEP draw-
ing with 50% probability ellipsoids,oH-atoms omitted
for clarity). Selected bond lengths [A] and angles [°]:
A u l-A u l' 3.1613(8), A ul-A u2 3.0499(6), Aul-Asl
2.4040(8), Aul-As2 2.4066(8), Au2-Ge 2.3235(10),
Au2-Cl 2.297(2), Ge-Cll 2.171(2), Ge-C12 2.166(2),
Ge-C13 2.151(3); Asl-Aul-As2 168.52(3), Ge-Au2-Cl
173.87(6).
Fig. 2. Molecular structure of compound 2 (ORTEP draw-
ing with 50% probability ellipsoids, H-atoms omitted for
clarity). Selected bond lengths [A] and angles [°]: Au-Ge
2.3884(4), Au-As 2.4117(4), Au--Au'2.9415(4), As-Cll
1.927(3), As-C21 1.926(3), As-C31 1.930(3), Ge-Cll
2.1829(10), Ge-C12 2.1782(10), Ge-C13 2.1750(10); Ge-
Au-As 169.353(13), Cll-Ge-C12 100.91(4), Cl 1-Ge-C13
101.90(4), C12-Ge-C13 100.97(4), Cl 1-Ge-Au 116.90(3),
C12-Ge-Au 117.75(3), C13-Ge-Au 115.73(3).
CH2(AsPh2)2 + 2 (M e2S)AuCl
-* 2 Me2S + CH2(AsPh2AuCl)2
2 CH2(AsPh2AuCl)2 + 2 GeCl2(dioxane)
—►2 (dioxane)
+ {[CH2(AsPh2Au)2]2}2+ 2 [ClAuGeCl3]_
Single crystals (monoclinic, space group P2[/c,
Z = 4) were obtained upon layering the solution of
the compound in tetrahydrofuran with hexane con-
taining a few drops of benzene. An X-ray diffraction
analysis showed that these clear crystals (not dried
in a vacuum) contain both tetrahydrofuran and ben-
zene in the lattice.
again generally quite similar to the structure of
Ph3PAuGeCl3[2].
B is[bis-id, n '(diphenylarsinom ethane)gold(I)](2+)
bis[C hloro(trichlorogerm anito)gold(I)(l-)] (3)
The main component of the lattice is
a
Bis(diphenylarsino)methane (dpam) is readily
converted into its bis[chlorogold(I)] complex
(dpam)(AuCl)2 by reaction with two equivalents
of chloro(dimethyl sulfide)gold(I) in tetrahydro-
furan at ambient temperature. Treatment of the
resulting clear solution with two equivalents of
GeCl2(dioxane) at room temperature affords colour-
less crystals (53% yield, m.p. 155°C). After
drying in a vacuum the analytical data of the
weathered crystals indicate a net composition of
(dpam)2Au4Ge2Clg. Longer reaction times (20 h)
did not lead to any changes in the composition.
Upon work-up of the mother liquor a yellow sticky
mass was obtained which could not be charac-
terized.
centrosymmetrical unit composed of a dication
{[(dpam)Au]2}2+ flanked by two [ClAuGeCl3]~
anions which have short interionic contacts Aul-
-Au2/Aul'--Au2' = 3.0499(6) A (Fig. 3). To-
gether with the transannular contact A ul--A ul'
=
3.1613(8) A, the four gold atoms form a
Z-shaped tetraatomic sequence [Au2--Aul--Aul'
118.833(14)°]. Under the influence of these
gold-gold interactions, the axes Asl-Aul-As2
[168.52(3)°] and Ge-Au2-Cl [173.87(6)°] deviate
strongly from the 180° standard, and are “crossed”
with an dihedral angle Cl-Au2--Aul-Asl of 110.7°.
The eight-membered ring of the dication is in an
elongated chair conformation.
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U. M. Tripathi et al. ■The Trichlorogermanite(II) Anion and its Gold(I) Complexes
The trichlorogermanite(II) ligand in the anions
942
has Ge-Cl distances [2.151(3), 2.166(2), 2.171(2)
ÄJ and Cl-Ge-Cl angles [101.09(11), 101.15(11),
102.29(11)°] in narrow ranges. The latter are
slightly larger than those in (Ph3As)AuGeCl3
(above), and the distances are significantly shorter,
indicating a stronger trans influence of the chlo-
ride ligand as compared to the arsine ligand, shift-
ing both parameters a little closer to the tetrahedral
standards (as in GeCU).
It is very surprising that the [Cl-Au-GeC^]-
anions are not undergoing insertion of a sec-
ond equivalent of GeCh available in the above
1:2:2 reaction mixture. The symmetrical anion
[C^Ge-Au-GeC^]“ is a known species and has
been structurally characterized [3] as a compo-
nent of the tetranuclear salt {[(PhMe2P)2Au]+
[Au(GeCl3)2]_ }2- Even a tricoordinate complex
Fig. 4. Molecular structure of the cation of compound 4
(ORTEP drawing with 50% probability ellipsoids, H-
atoms omitted for clarity; only one of the two crystal-
lographically independent cations is shown, the corre-
sponding values of the second cation are given in paren-
theses). Selected bond lengths [A] and angles [°]: Aul-
P1 2.256(2) [2.243(2)], Aul-Nl 2.134(5) [2.119(5)]; Pl-
Aul-Nl 176.7(2) [179.6(2)].
[Au(GeCl3)3]2_ was observed in
a salt with
[(dppm)Au]22+ counterions [4], Attempts to force
the above reaction by heating to reflux temperature
lead to decomposition.
It is unclear why the reaction is not proceeding
to completion in the (dpam) system. The failure of
synthetic attempts may be ascribed to steric con-
gestion in the tetranuclear complex, implying that
the ion-triple is very tightly bonded and that none
of the anions is released from the cluster for fur-
ther insertion. The results of recent measurements
of the bond energy associated with aurophilic inter-
actions (8 -11.5 kcal/mole) [5] are indeed indicative
of very significant bond strengths in related aggre-
gates, however, and therefore this conclusion is not
unreasonable.
Suitable crystals (colourless, triclinic, space
group Pi, Z = 4) could be grown with [PFö]- as
the counterion. The lattice contains no solvent. It
is composed of two crystallographically indepen-
dent cations [(Et3N)Au(o-Tol)3]+ (Fig. 4) and an-
ions [PFö]~. The two anions have a standard octa-
hedral geometry with very similar dimensions.
A superposition of the two cations shows several
significant differences in the conformation of the
amine and phosphine ligands. Only the C3N-AU-
PC3 cores are very similar with almost perfectly
linear axes PI-A ul-N l 176.7(2) and P2-Au2-N2
179.6(2)°. The two phosphine ligands are both in
a propeller-type conformation with opposite direc-
tionality (left- and right-handed). However, the two
triethylamines show approximate threefold (N2)
(Triethylamine)[tri(o-tolyl)phosphine]gold(I)
hexafluorophosphate (4)
Mixed ligand complexes of gold(I) with a combi- and mirror symmetry (N1 ), respectively, as demon-
nation of hard and soft Lewis-base donor molecules
are rare. An early example has been the (quinoclu-
dine)(triphenylphosphine)gold(I) tetrafluoroborate,
strated in the projection of the two cations along
their principal molecular axes (Fig. 5).
As expected for a bulky (o-Tol)3P ligand, the
with an N-Au-P axis [7]. In the course of the Au-P distances are rather long [2.243(2) and
present and some earlier studies, a similar complex
with NEt3 and (o-tolyl^P was isolated and struc- trans position, still show a distinct lengthening
2.256(2) A], and even the Au-N distances, in the
turally characterized. This compound was obtained
when phosphine complexes were treated with var-
[2.134(5) and 2.119(5) Ä], at least as compared
to gold(I) complexes of ammonia. However, the
ious reagents in the presence of triethylamine as a data for the quinuclidine analogue are similar [Au-N
base [6 ].
2.11(1), Au-P 2.240(4) A] [7],
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943
U. M. Tripathi et al. ■The Trichlorogermanite(II) Anion and its Gold(I) Complexes
Fig. 5. Projection of the two cations of compound 4 along their principal molecular axes, showing the approximate
threefold (N2) (left) and mirror symmetry (Nl) (right) of the two triethylamines.
Experimental Part
(CDCI3) b 131 - 7.52 (m, Ph). 13C{'H}<5 133.28, 131.88,
131.28, 129.76 (all s, meta, ipso, para, and ortho).
General: All experiments were routinely carried out in
an atmosphere of dry purified nitrogen. Standard equip-
ment was used throughout. Starting materials were pur-
chased except for GeCl2(dioxane) [8 ] and (Ph^As)AuCl
[9,10].
Ci8Hl5AsAuChGe (682.13)
Calcd C 31.69 H 2.20 Au 28.88 Cl 15.59%,
Found C 32.00 H 2.28 Au 28.70 Cl 15.52%.
Bis{Ibis(diphenylarsino)methane]gold(I)}(+2)
bis[chloro(trichlorogermanito)gold(I)]
(-1) ■2 benzene ■2 tetrahydrofuran (3)
Tetraphenylphosphonium trichlorogermanite(II) (1)
To a suspension of (Me2S)AuCl (0.24 g, 0.81 mmol)
in 15 ml of tetrahydrofuran was slowly added a solu-
tion of (Ph2As)2CH2 (0.19 g, 0.40 mmol) in the same
amount of the same solvent and the mixture stirred for 2
h at 20°C to give a clear solution. Solid GeCl2(dioxane)
(0.19 g, 0.81 mmol) was added to the solution and the
mixture was again stirred at 20 °C for 20 h. The resul-
tant solution was layered with hexane and a few drops
of benzene to crystallize the product, which after short
evacuation was free of solvents (0.23 g, 53.5 % yield,
m. p. 155°C). - NMR: 1H (CD3CN) 6 2.12 (s, 2H, CH2),
7.30- 7.48 (m, 20 H, Ph). 13C{'H}<5 140.8, 132.7, 128.5
(all s, para, meta, ortho; ipso and CH2 not observed). MS
(FAB): m/e 1606 [100%, (dpam)2Au3Cl2], 1373 [40%,
(dpam)2Au2Cl], 900.9 [87%, (dpam)Au2Cl], 669 [10%,
(dpam)Au],
A slurry of GeCl2(dioxane) (1.90 g, 8.2 mmol) and
Ph4P+Cl_ (3.08 g, 8.2 mmol) in 20 ml of tetrahydronaph-
thalene was heated to 90 °C for 15 min. Dioxane liberated
during the reaction was stripped off in a vacuum (1 0 - 2
mm Hg), and the evaporation was continued for 12 h with
stirring to ensure the complete removal of the dioxane.
The white precipitate was filtered off in the cold, washed
three times with 1 0 ml of pentane and dried in a vacuum.
The product was recrystallized from CH2CI2 (yield 4.20
g, 98.8%, m. p. 186 °C). - MS (FAB): m/e = 338.9 [100%,
Ph4 P+], 261.7 [2.8%, Ph3P],
C24H2oCl3GeP (518.31)
Calcd C 55.61 H 3.89 Cl 20.52%,
Found C 55.79 H3.91 Cl 20.43%.
(Triphenylarsine)gold(I) trichlorogermanite(II) (2)
C5oH44As4Au4Ge'>Cl8 (2161.27)
Calcd C 27.79 H 2.03 Au 36.46 Cl 13.40%,
Found C 28.00 H2.10 Au 36.51 Cl 13.12%.
To a solution of (Ph3As)AuCl (0.42 g, 0.76 mmol) in
25 ml of tetrahydrofuran 0.18 g (0.77 mmol) of solid
GeCl2(dioxane) was added at 20 °C and the mixture
was heated to reflux for 5 h. The product was precip-
itated by addition of hexane. Crystallization from hex-
ane/chloroform [2:1] resulted in 4.7 g (90% yield) of
(Triethylamine)[tri(o-tolyl)phosphine]gold(I) hexafluo-
rophosphate (4)
The preparation and isolation of the compound was
product (m.p. 183°C with decomposition). - NMR: ‘H first reported in Ref. [6 ].
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944
Table I. Crystal data, data collection and structure refinement.
U. M. Tripathi et al. •The Trichlorogermanite(II) Anion and its Gold(I) Complexes
1
2
3 • thf ■benzene
4
Crystal data:
Formula
Mr
Crystal system
Space group
a (A)
b (A)
c (A)
Q (°)
ß (°)
C24H20ChGeP
518.31
triclinic
P\
7.328(1)
11.878(2)
13.465(1)
93.85(1)
93.68(1)
96.54(1)
1158.7(3)
1.468
C^H-^AstAuiCuGCO
C 36 H 3 o A s 2 A u 2C l6G e 2
C 2 7 H 3 6 A u F 6N P 2
747.47
triclinic
P\
11.082(2)
15.117(4)
19.666(4)
86.82(2)
88.62(2)
71.32(2)
3116.2(12)
1.593
1364.25
monoclinic
C2/c
19.439(2)
11.173(1)
19.495(2)
90
105.01(1)
90
2604.8(4)
2.216
1230.80
monoclinic
P2\/c
14.222(3)
20.373(3)
13.710(3)
90
106.54(1)
90
3808.0(13)
2.147
7 (°)
V (A3)
Pcalc (g-cm~3)
Z
2
4
4
4
F(000)
524
2544
2312
1472
/j (MO-Kq ) (cm- 1)
17.45
106.32
105.03
48.75
Data collection:
T(°C)
-80
-74
-78
-78
Scan mode
hkl range
LU—9
-9 —9, 0— 15,
-17— 17
C0
to —9
-17— 17,-25—0,
0— 16
LO
-24—24, -14—0,
-24—24
0— 13,-17— 18,
-24—24
sin (9 /A)max (A ')
Measured reflections
Unique reflections
0.66
5573
0.64
8928
0.62
7784
0.62
11336
11331 [ f l m t = 0.0000]
11281
5773 [/?int = 0.0000]
7463 [flin t = 0.0251]
6794
4471 [flint = 0.0198]
4182
Refls. used for refinement 5542
Refinement:
Refined parameters
262
217
381
662
Final R values [I > 2cr(I)]
R\l*}
0.0342
0.0893
0.0356
0.0831
0.0404
0.1100
0.0200
0.0431
wfl2[b]
<0.001
<
0.001
<0.001
<0.001
(shift/esd)max
Pfin(max/min) (eA-3 )
2.351/—0.915
0.499/-0.651
1.002/-0.931
1.325/—1.765
M R = I ILFol-IFcll / 1IF0I; [b] wR2 = [I w(F2 - FC2) / 1 v^F2)2]1/ 2; w = M[a2(F2) + (ap)2 + bp];p = {F20 + 2F2)/3; a = 0.0442 (1),
0.0262 (2), 0.0528 (3), 0.0752 (4); b = 1.00 (1), 0.00 (2), 8.57 (3), 9.59 (4).
Crystal structure determinations
with fixed isotropic contributions (UiS0(fix) = 1.5 x Ueq of
the attached C atom). Further information on crystal data,
data collection and structure refinement are summarized
in Table I. Important interatomic distances and angles are
shown in the corresponding Figure Captions. Anisotropic
thermal parameters, tables of interatomic distances and
angles, and atomic coordinates have been deposited with
the Fachinformationszentrum Karlsruhe, Gesellschaft für
wissenschaftlich-technische Information mbH, D-76344
Eggenstein-Leopoldshafen. The data are available on re-
quest on quoting CSD-408892 (1), -408894 (2), -408891
(3), and -408893 (4).
Specimens of suitable quality and size were mounted in
glass capillaries and used for measurements of precise cell
constants and intensity data collection on an Enraf No-
nius CAD4 diffractometer (Mo-KQradiation, A(Mo-KQ)
= 0.71073 A). During data collection, three standard re-
flections were measured periodically as a general check
of crystal and instrument stability. No significant changes
were observed. Lp correction was applied, and data of
2, 3, and 4 were corrected for absorption. The structures
were solved by direct methods (SHELXS-86) [11] and
completed by full-matrix-least squares techniques against
F2 (SHELXL-93) [12], The thermal motion of all non-
hydrogen atoms was treated anisotropically. All hydro-
gen atoms were placed in idealized calculated positions
Acknowledgements
This work was supported by Deutsche Forschungsge-
and allowed to ride on their corresponding carbon atoms meinschaft, Alexander von Humboldt Stiftung (U. M. T.),
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U. M. Tripathi et al. •The Trichlorogermanite(II) Anion and its Gold(I) Complexes__________________________945
Fonds der Chemischen Industrie, and - through the dona- The authors thank Mr. J. Riede for establishing the X-ray
tion of chemicals - by Degussa AG and Heraeus GmbH.
data sets.
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[12] G. M. Sheldrick, Progr. for the Refinement of Struc-
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[4] A. Bauer, H. Schmidbaur, J. Chem. Soc., Dalton
Trans. 1997, 1115.
[5] J. Zank, A. Schier, H. Schmidbaur, J. Chem. Soc.,
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[6] U. M. Tripathi, A. Bauer, H. Schmidbaur, J. Chem.
Soc., Dalton Trans. 1997, 2865.
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