Crystal and molecular structures of the sulfurization and selenation products of bis[bis(trimethylsilyl)amino]germanium(II). Crystal structure of (triphenylphosphine)gold(I) bis(trimethylsilyl)amide

Article abstract of DOI:10.1515/znb-2000-0501

Treatment of bis[bis(trimethylsilyl)amino]germanium(II) with elemental sulfur or selenium affords high yields of the corresponding monosulfide [(Me₃Si)₂N]₂GeS and selenide [(Me₃Si)₂N]₂GeSe, respectively. The crystalline products have now been shown to be cyclic dimers with (GeS/Se)₂ four-membered rings by X-ray single crystal structure analysis. The crystal structure of (triphenylphosphine)gold(I) bis(trimethylsilyl)amide (Ph₃P)Au-N(SiMe₃)₂ has also been determined. The molecule is a monomer with a tricoordinate nitrogen atom in a planar configuration [Si₂NAu]. The compound does not undergo insertion of the bis[bis(trimethylsilyl)amino]germylene.

Full text of DOI:10.1515/znb-2000-0501

Crystal and Molecular Structures of the Sulfurization and Selenation
Products of Bis[bis(trimethylsilyl)amino]germanium(II). Crystal
Structure of (Triphenylphosphine)gold(I) Bis(trimethylsilyl)amide
Gerald L. Wegner, Alexander Jockisch, Annette Schier, and Hubert Schmidbaur
Anorganisch-chemisches Institut, Technische Universität München,
Lichtenbergstrasse 4, D-85747 Garching, Germany
Reprint requests to Prof. Dr. H. Schmidbaur. E-mail: H.Schmidbaur@lrz.tum.de
Z. Naturforsch. 55 b, 347-351 (2000); received March 8 , 2000
Germylenes, Germanium(II) Amides, Sulfurization
Treatment of bis[bis(trimethylsilyl)amino]germanium(II) with elemental sulfur or sele-
nium affords high yields of the corresponding monosulfide [(Me.^Si^NLGeS and selenide
[(Me.^SihN^GeSe, respectively. The crystalline products have now been shown to be cyclic
dimers with (GeS/Se)2 four-membered rings by X-ray single crystal structure analysis. The
crystal structure of (triphenylphosphine)gold(I) bis(trimethylsilyl)amide (Ph;?P)Au-N(SiMe3)2
has also been determined. The molecule is a monomer with a tricoordinate nitrogen atom
in a planar configuration [SiiNAu]. The compound does not undergo insertion of the
bis[bis(trimethylsilyl)amino]germylene.
Introduction
pound into the Au-N bond could lead to a germyl-
gold(I) species with an extremely crowded germyl
substituent. Our experiments have shown, however,
that the two reagents give no addition product what-
soever within the stability range of the starting mate-
rials. Even after extended periods of time at reaction
temperatures up to 60 °C the two components are
recovered unchanged.
In order to obtain direct information about the
steric crowding of the gold(I) complex we deter-
mined its crystal structure. We also reinvestigated
the sulfurization and selenation of compound 1 in
order to clarify the degree of association of the ox-
idation products.
Bis[bis(trimethylsilyl)flmmo]germanium(II) was
first prepared by Lappert et al. as one of the early
examples of a stable carbene analogue with two-
coordinate germanium(II) centres [1,2]. Like the re-
lated bis[bis(trimethylsilyl)m^r/zy/]germanium(II)
molecule [3], compound 1 is known to undergo
many redox and insertion reactions, including oxi-
dation by all four of the elemental chalcogens (X =
O, S, Se, Te) [4]. The products have the formula
{[(Me^Si^N^GeX},,, but the number n has been
specified only for X = O and X = Te. These com-
pounds have been shown [4, 5] to be cyclic dimers
with four-membered rings (GeO)2 and (GeTe)2 , re-
spectively.
In the course of our recent studies of insertion
reactions of germanium(II) compounds into func-
tional gold(I) complexes [6-11] we also investi-
gated the reactivity of (triphenylphosphine)gold(I)
bis(trimethylsilyl)amide [1 2 ] towards [(Me3Si)2-
N]2Ge. An insertion of the germanium(II) com-
Results and Discussion
Colourless (triphenylphosphine)gold(I) bis(tri-
methylsilyl)amide (1 ) [1, 2 ] and low-melting
yellow bis[bis(trimethylsilyl)amino]germanium(II)
[1 2 ] were readily prepared as crystalline solids fol-
lowing the literature methods. The analytical and
Me3Si^
Me3S i \ ^SiMe;}
^SiM e3
Sil\fle3
N— SiMe3
/SiMe3
Ph3P—Au— N
+
G e ^
— - jjU
Ph3P—Au— G e— N
I
SiM e3
(1)
N j — SiMe3
Me3Si
. / N\
M e3Si
SiM e3
0932-0776/00/0500-0347 $ 06.00 © 2000 Verlag der Zeitschrift für Naturforschung, Tübingen • www.znaturforsch.com
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348
G. L. Wegner et al. • [(N ^S ih N fcG eS , [(N ^ S i^ N h G e S e , and (Ph3P)AuN(SiM e3)2
C23
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 [°]:
Au-P 2.2281(8), Au-N 2.026(3), N-Sil 1.713(3), N-Si2
1.708(3); P-Au-N 176.44(8), Sil-N-Si2 125.76(16), Sil-
N-Au 110.39(14), Si2-N-Au 119.57(15).
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 [°]: G el-N l
1.8463(4), Ge 1-N2 1.845(4), Ge 1-S 12.2257( 13), Gel -S2
2.2275(13), Ge2-N3 1.836(4), Ge2-N4 1.841(4); Ge2-
S1 2.2479(13), Ge2-S4 2.2267(14), N l-S ill 1.771(4),
N 1-Si 12 1.771(4), N2-Si21 1.762(4), N2-Si22 1.756(4),
N3-Si31 1.767(4), N3-Si32 1.758(4), N4-Si41 1.772(4),
N4-Si42 1.767(4); N l-G el-N 2 110.92(17), N l-G el-
S1 109.72(12), N l-G el-S2 115.65(13), N2-Gel-Sl
115.70(13),N2-Gel-S2 109.91(13),Sl-G el-S2 94.15(5),
N3-Ge2-N4 110.31(17), N3-Ge2-Sl 111.09(12), N3-
Ge2-S2 111.34(12), N4-Ge2-Sl 113.18(13), N4-Ge2-S2
116.40(13), Sl-Ge2-S2 93.57(5), G el-Sl-G e2 85.85(4).
Gel-S2-Ge2 86.32(5).
spectroscopic data of the products were in agree-
ment with literature readings where available, and
a few complementary measurements have been car-
ried out (Experimental Part).
Attempts to react equimolar quantities of the two
components in various solvents at temperatures up
to 60 °C were all unsuccessful. The two compounds
were left unchanged as demonstrated by NMR spec-
troscopy. No insertion of the germylene into the
Au-N bond occurred. At higher temperatures de-
composition ensued.
is shown in Fig. 1. The large ligands are clearly
protecting the gold atom against an approach of
other molecules of 1 and of other reactants.
The failure of these experiments probably has
to be ascribed to both excessive steric hindrance
by the bulky bis(trimethylsilyl)amino groups at the
gold and germanium atoms and thermodynamic sta-
bilisation of the germylene due to 7r-interactions be-
tween the free electron pairs of the nitrogen atoms
and the electron deficient germanium centre.
In order to delineate the geometrical details of
the gold(I) component 1 the crystal and molecu-
lar structure was determined by single crystal X-
ray diffraction. Such a study of a compound with a
Au-N-Si linkage was also desirable in the context
of recent structural work on the analogous gold(I)
siloxides [13] and silthiolates [14] with Au-O-Si
and Au-S-Si linkages, respectively.
The gold atoms are in the expected linear coordi-
nation by a phosphorus and a nitrogen atom [P-Au-
N 176.44(8)°]. The Au-N distance [Au-N 2.026(3)
A] is similar to the data of related imide compounds,
e. g. the phthalimide with the same PI13P ligand [Au-
N 2.040(4) and 2.028(4) A for the solvent-free crys-
tal ortheCH C^ solvate, respectively] [15]. The sum
of the angles at the nitrogen atom amounts to only
355.72°, indicating a significant deviation from pla-
narity.
The environment of the germanium atom in
the germylene was probed by single crystal X-ray
diffraction studies of the corresponding sulfide and
selenide. These derivatives are available through di-
Crystals of (Ph3P)AuN(SiMe3)2 (1), are triclinic, rect sulfurization and selenation in tetrahydrofuran
space group P i, with two molecules in the unit cell. as described in the literature [4]. White colourless
The structure of the individual molecules, between
which there are no conspicuously short contacts,
crystals were obtained in high yields. The crystals of
the two compounds are not isomorphous, and they
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349
G. L. Wegner et al. • [(M e^Si^N ^G eS, [(M e^Si^N loG eSe, and (Ph3P)AuN(SiM e3)2
the two germanium atoms and the central carbon
atom of the pentane solvent molecule. This solvent
molecule has the all-trans conformation of an ex-
tended hydrocarbon chain, while the Ge2Se2N4 core
of the dimeric bis(amino)germanium sulfide has two
inequivalent germanium atoms bridging equivalent
selenium atoms. The four-membered ring (GeSe)2
is planar with a sum of internal angles of 360.00(2)°,
and with angles of 93.98(2)° at Ge2, 94.44(2)° at
Gel, and 85.79(2)° at Se.
Similar to the situation in the gold complex 1,
and in many other metal disilylamides, the configu-
ration at the nitrogen atoms in molecules 2 and 3 is
close to planar. This configuration leads to a maxi-
mum shielding of the (GeS)2 and (GeSe)2 cores of
molecules 2 and 3, respectively.
A comparison of the data for [(Me3Si)2N]4Ge2E2
with E = O, S, Se, Te shows great similarities.
The basic structure follows the same principle in
all cases, except for a gradual widening of the four-
membered ring following the growth of the covalent
radius of the chalcogen atoms: Ge-O 1.805(9) A (av-
erage), Ge-S 2.238(1) A, Ge-Se 2.372(1) A, Ge-Te
2.595(2) A.
Fig 3. Molecular structure of compound 3 (ORTEP draw-
ing with 50% probability ellipsoids, H-atoms omitted for
clarity). Selected bond lengths [A] and angles [°]: Ge 1-N 1
1.8516(19), Gel-Se 2.3678(4), Ge2-N2 1.857(2); Ge2-
Se 2.3766(4), N1-Si 1 1.767(2), Nl-Si2 1.759(2), N2-Si3
1.766(2), N2-Si4 1.771(2); N l-G el-N l' 111.21(13), N l-
Gel-Se 110.91(6), N1-Gel-Se' 114.24(6), Se-Gel-Se'
94.44(2), N2-Ge2-N2' 114.25(13), N2-Ge2-Se 108.26(7),
N2-Ge2-Se' 115.29(6), Se-Ge2-Se' 93.98(2), Gel-Se-
Ge2 85.793(16).
All Ge2E2 rings are planar, with deviations from
the square geometry smallest for E = O [average
Ge-O-Ge 87.5(4)°, O-Ge-O 92.5(4)° ] and larger and
almost uniform for E = S, Se, Te [average Ge-Te-Ge
85.58(6)°, Te-Ge-Te 94.38(6)°]. The homologous
series thus shows virtually no structural anomalies.
are also not isomorphous with the related oxide and
telluride [4,5].
Crystals of the sulfide 2 from pentane are mono-
clinic, space group P2i/c, with Z = 4 molecules
in the unit cell. There is no solvent in the crys-
tals. The individual molecules represent dimers of
the original germylene sulfide units. These dimers
have no crystallographically imposed symmetry,
but the positions of the core atoms Ge2S2N4 obey
quite closely the symmetry requirements of point
group Ö2h (Fig. 2). The four disilylamino groups
are substituents of a four-membered ring (GeS)2 ,
which is virtually planar [sum of the internal angles
359.89(5)°], but deviates very significantly from
the geometry of a square. The angles at the ger-
manium atoms [Ge2 93.57(5), Gel 94.15(5)°] are
larger than 90°, while the angles at the sulfur atoms
[SI 85.85(4), S2 86.32(5)°] are smaller.
By contrast with the findings for 2, the selenide 3
crystallizes from «-pentane in the monoclinic space
group C2/c with Z = 4 molecules and four molecules
of solvent C5H 12 in the unit cell. Like with 2, the in-
dividual molecules are dimers of the germylene se-
lenide units, but these dimers obey crystallographic
C2 symmetry with the twofold axis passing through
Experimental Part
All experiments were carried out routinely in an inert
atmosphere of dry pure nitrogen. Standard equipment was
used throughout.
(Triphenylphosphine)gold(I) bis(trimethylsilyl)amide (1)
[ 12]
To a slurry of (Ph3P)AuCl (0.69 g, 1.39 mmol) [16] in
tetrahydrofuran (8 ml) was added dropwise with stirring
1.39 ml of a 1.0 m solution of (Me3Si)2NLi in tetrahydro-
furan at 20 °C. After 1h the solvent was removed in vacuo.
Extraction of the residue with pentane (15 ml) and evap-
oration of the solvent from the extract left a crystalline
colourless solid (0.47 g, 54.6% yield). 'H NMR (CöDö):
0.57, s, 18H, Me; 6.92-7.45, m, 15H, Ph. 13C{'H}: 6.82,
s, Me; 128.6, s, C,; 131.2, d, ./(PC) 2.4, Cp; 131.3, d,
/(PC) 9.5, Cm; 134.2, d, /(PC) 13.0, C0. 31P{'H}: 34.7,
s. - C24H33AuNPSi2 (619.63): Calcd C 46.51, H 5.53, N
2.26. Found C 46.32, H 5.37, N 2.12%.
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350
G. L. Wegner et al. ■[(M e^SibN ^G eS, [(Me3Si)2 N ]2GeSe, and (Ph3P)AuN(SiMe3)2
Table 1. Crystal data, data collection, and structure refinement for compounds 1, 2, and 3.
1
2
3
C5H,2
Crystal data
Formula
Mr
Crystal system
Ci4H^AuNPSi?
619.63
triclinic
Ci4H72Ge->N4STSig
850.88
monoclinic
C29H84Ge2N4SeTSig
1016.82
monoclinic
Space group
a (A)
b ( A)
c (A)
a (°)
ß C )
7 (°1
V(A3)
PI
P2\/c
C2/c
8.560(1)
12.357(1)
13.606(2)
71.27(1)
79.89(1)
74.56(1)
1307.4(3)
1.574
9.074(2)
41.117(10)
12.508(3)
90
106.61(1)
90
4472.0(18)
1.264
4
16.288(1)
27.595(4)
11.604(1)
90
106.09(1)
90
5011.3(9)
1.348
4
Pcalc (g-Cm 3)
Z
2
612
2120
F(000)
1808
ju(Mo Ka ) (cm“ 1)
28.67
57.90
16.73
Data collection
T(°C)
-120
-110
-120
hkl Range
-1 0 —»49, 0— 15,-16—>17
0.64
5965
5690 [Aim = 0.0112]
Psi-scans
-11 — 10, 0—50, 0— 15
0.62
9139
8748 [/?,nt = 0.0368]
Psi-scans
-2 0 —20, 0—35 ,-1 4 —3
0.64
7279
5470 [/?im= 0.0192]
Psi-scans
sin(6tyA)max (A-1)
Measured reflections
Unique reflections
Absorption correction
0.444/0.999
0.813/0.999
0.600/0.999
Fmin/Tmax
Refinement
Refined parameters
Final RVa] [I >2<r(I)]
Final w/?2lb' [I >2cr(I)]
262
361
0.0553
0.1082
<0.001
0.925/-1.030
205
0.0228
0.0574
<0.001
1.419/-1.214
0.0489
0.1316
<0.001
1.597/-2.241
(shift/error)max
o
Pfin(max/min) (eA-3)
[al R = I (|IF0I- IFCI|)/I IF0I; Ib] wR2 = {[I w(F02 - Fc2)2]/! [w(F02)2]}1/2; w = 1/[<72(F02) + (ap)2 + bp]; p = (F02 +
2Fc2)/3; a = 0.0396 (1), 0.0369 (2), 0.0353 (3); b = 0.87 (1), 16.33 (2), 7.13 (3).
Treatment of complex 1 (0.42 g, 1.07 mmol) [12] with
[Me3Si)2N]2Ge (0.66g, 1.07 mmol) [3] in pentane (20ml)
at -50 °C, +20 °C or in boiling hexane (60 °C) left the
components unchanged as shown after work-up by NMR
spectroscopy.
The selenide 3 was prepared similarly from 1.98 g (5.04
mmol) of the germylene and 0.40 g (5.04 mmol) of grey
selenium (2.32 g, 90.5% yield). 'H NMR (C6D6): 0.50,
s. 13C {1H}: 6.96, s. 29Si{'H}: 5.50, s. The crystals con-
tain 1 mole equivalent of pentane. C29H84Ge2N4Se2Sig
(1016.82): Calcd C 34.26, H 8.33, N 5.51: Found C 33.37,
H 7.91, N 5.57%.
Bis[bis(trimethylsilyl)amino]germanium sulfide (2) and
selenide (3)
Crystal structure determinations: Specimens of suit-
able quality and size of compounds 1, 2, and 3 were
A mixture of [(Me3Si)2N]2Ge (2.08 g, 5.29 mmol)
[3] and sulfur (0.17 g, 5.29 mmol) was suspended in mounted in glass capillaries and used for measurements
tetrahydrofuran (15 ml) and heated to reflux for 24 h. The
resulting reaction mixture was filtered at 20 °C and the
solvent removed in vacuo. Recrystallization from pentane
at -30 °C gave colourless crystals (1.35 g, 60% yield). 1H
NMR (C6D6): 0.50, s. 13C{'H}: 7.03, s. 29Si{'H}: 5.79,
s. C24H72Ge2N4S2Si8 (850.87): Calcd C 33.90, H 8.50, N
6.60, S 7.50. Found C 32.66. H 8.49, N 6.15, S 8.04%.
of precise cell constants and intensity data collection on
an Enraf Nonius CAD4 diffractometer (Mo-KQ radia-
tion, A(Mo-Kq) = 0.71073 A) . During data collection,
three standard reflections were measured periodically as
a general check of crystal and instrument stability. No
significant changes were observed. Lp correction was ap-
plied and intensity data were corrected for absorption
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351
G. L. Wegner et al. ■[(Me3Si)2 N]2GeS, [(Me3Si)2N]2GeSe, and (Ph3P)AuN(SiM e3)2
on crystal data, data collection and structure refinement
are summarized in Table 1. Important interatomic dis-
tances and angles are shown in the corresponding figure
captions. Anisotropic thermal parameters and tables of in-
teratomic distances and angles have been deposited with
the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK. The data are available
on request on quoting CCDS 141598 - 141600.
effects. The structures were solved by direct methods
(SHELXS-97) and completed by full-matrix-least squares
techniques against F2 (SHELXL-97). The thermal motion
of all non-hydrogen atoms was treated anisotropically.
All hydrogen atoms were placed in idealized calculated
positions and allowed to ride on their corresponding car-
bon atoms with fixed isotropic contributions (UiSO(fix) =
1.5 x Ueq of the attached C atom). Further information
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Chem. 626, 374 (2000).
[11] H. Schmidbaur (ed.): Gold: Progress in Chemistry,
Biochemistry and Technology, p. 633 ff., J. Wiley
& Sons, Chichester (1999).
[2] M. J. S. Gynane, D. H. Harris, M. F. Lappert, P. P.
Power, P. Riviere, M. Riviere-Baudet, J. Chem. Soc.,
Dalton Trans. 1977, 2004.
[3] P. J. Davidson, D. H. Harris, M. F. Lappert, J. Chem.
Soc., Dalton Trans. 1976, 2268.
[12] A. Shiotani, H. Schmidbaur, J. Am. Chem. Soc. 92,
7003 (1970).
[13] A. Bauer, A. Schier, H. Schmidbaur, Acta Crystal-
logr. C51, 2030 (1995).
[14] A. Bauer, W. Schneider, A. Schier, H. Schmidbaur,
Inorg. Chim. Acta 251, 249 (1996).
[15] P. Lange, A. Schier, J. Riede, H. Schmidbaur,
Z. Naturforsch. 49b, 642 (1994).
[4] P. B. Hitchcock, H. A. Jasim, M. F. Lappert, W.-P.
Leung, A. K. Rai, R. E. Taylor, Polyhedron 10, 1203
(1991).
[5] D. Ellis, P. B. Hitchcock, M. F. Lappert, J. Chem.
Soc., Dalton Trans. 1992, 3397.
[6 ] A. Bauer, A. Schier, H. Schmidbaur, J. Chem. Soc.,
Dalton Trans. 1995, 2919.
[7] A. Bauer, H. Schmidbaur, J. Am. Chem. Soc. 118,
5324(1996).
[16] N. C. Baenziger, W. E. Bennett, D. M. Soboroff,
Acta Crystallogr. B 32, 962 (1976).
[8 ] A. Bauer, H. Schmidbaur, J. Chem. Soc., Dalton
Trans. 1997, 1115.
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