Synthesis, structures, and reactivity of alkylgermanium(II) compounds containing a diketiminato ligand

Article abstract of DOI:10.1021/om0203328

Reaction of [HC(CMeNAr)₂]GeCl (Ar = 2,6-iPr₂C₆H₃) with RLi (R = Me, nBu) in diethyl ether at -78 °C yielded the alkylgermanium(II) compounds [HC(CMeNAr)₂]GeR (R = Me (5), nBu (6)), which are monomeric

Full text of DOI:10.1021/om0203328

5216
Organometallics 2002, 21, 5216-5220
Syn th esis, Str u ctu r es, a n d Rea ctivity of
Alk ylger m a n iu m (II) Com p ou n d s Con ta in in g a
Dik etim in a to Liga n d †
Yuqiang Ding, Qingjun Ma, Herbert W. Roesky,* Regine Herbst-Irmer,
Isabel Uso´n, Mathias Noltemeyer, and Hans-Georg Schmidt
Institut fu¨r Anorganische Chemie der Universita¨t Go¨ttingen, Tammannstrasse 4,
D-37077 Go¨ttingen, Germany
Received April 25, 2002
Reaction of [HC(CMeNAr)2]GeCl (Ar ) 2,6-iPr2C6H3) with RLi (R ) Me, nBu) in diethyl
ether at -78 °C yielded the alkylgermanium(II) compounds [HC(CMeNAr)2]GeR (R ) Me
(5), nBu (6)), which are monomeric with a three-coordinate germanium center. Compound
5 was oxidized with sulfur and selenium to afford [HC(CMeNAr)2]GeMe(E) (E ) S (7), Se
(8)), in which a terminal GedE double bond is present. Treatment of 5 with trimethylsilyl
azide in hexane at room temperature gave [HC(C(CH2)NAr)CMeNAr]GeMe(N(H)SiMe3) (9),
containing a Ge-N single bond; the expected compound [HC(CMeNAr)2]GeMe(NSiMe3) with
a GedN double bond was not observed. The latter reaction proceeds with migration of a
hydrogen atom from a methyl group of the ligand backbone to the nitrogen atom bonded to
the silicon atom with formation of a methylene moiety. X-ray structural data are provided
for 5, 6, 8, and 9.
In tr od u ction
variation of the substituents on the ligand backbone,
were used to good advantage in the synthesis of such
compounds.
The chemistry of divalent germanium compounds has
received considerable attention over the past three
decades due to their carbene-like properties.1 Such
compounds are generally reactive and tend to oligomer-
ize or polymerize. However, Ge(II) compounds can be
stabilized kinetically by sterically demanding ligands
and/or thermodynamically by inter- and intramolecular
coordination. Indeed, numerous nitrogen-containing
bulky ligands have been used to stabilize these com-
pounds.2-9 Very recently, the chelating â-diketiminato
ligands [HC(CMeNR)2]- (R ) Ph,10 2,4,6-Me3C6H2,11 2,6-
iPr2C6H312-14), where steric flexibility is afforded by
Compounds of divalent germanium bonded to small
alkyl substituents (such as Me, Et, and Bu) are highly
reactive and therefore exist only as intermediates.15,16
Recently, compounds of composition LGeR, where L is
a bulky ligand and R is a small alkyl group, have been
investigated. J utzi and co-workers prepared the first
examples of such compounds by oxidative addition of
MeI to MamxGeR (Mamx ) methylamino-methyl-m-
xylyl; R ) Me, nBu) but did not characterize the
products by structural analysis.7 We have synthesized
[HC(CMeNAr)2]GeCl (1; Ar ) 2,6-iPr2C6H3).12 By me-
tathesis reactions compound 1 was converted to the first
structurally characterized germanium(II) hydride and
germanium(II) fluoride [HC(CMeNAr)2]GeF (2).13 More-
over, the first structurally characterized compounds of
multiply bonded heavier main group elements bearing
a halide, [HC(CMeNAr)2]GeX(S) (X ) F (3), Cl (4)),14
were prepared. Herein, we report the preparation and
the characterization of the alkylated germanium(II)
compounds [HC(CMeNAr)2]GeR (Ar ) 2,6-iPr2C6H3,
R ) Me (5), nBu (6)) and the resulting chalcogen de-
rivatives [HC(CMeNAr)2]GeMe(S) (7), [HC(CMeNAr)2]-
GeMe(Se) (8), [HC(C(CH2)NAr)CMeNAr]GeMe(N(H)-
SiMe3) (9), and [HC(CMeNAr)2]GeMe2(I) (10). Com-
pounds 5, 6, 8, and 9 were characterized by single-
crystal X-ray structural analysis.
† Dedicated to Professor Anton Meller on the occasion of his 70th
birthday.
(1) For recent reviews of divalent germanium: (a) Barrau, J .;
Escudie´, J .; Satge´, J . Chem. Rev. 1990, 90, 283. (b) Lappert, M. F.;
Rowe, R. S. Coord. Chem. Rev. 1990, 100, 267. (c) Neumann, W. P.
Chem. Rev. 1991, 91, 311. (d) Lappert, M. F. Main Group Met. Chem.
1994, 17, 183. (e) Barrau, J .; Rima, G. Coord. Chem. Rev. 1998, 178-
180, 593.
(2) Veith, M.; Becker, S.; Huch, V. Angew. Chem. 1989, 101, 1287;
Angew. Chem., Int. Ed. Engl. 1989, 28, 1237.
(3) Veith, M.; Becker, S.; Huch, V. Angew. Chem. 1990, 102, 186;
Angew. Chem., Int. Ed. Engl. 1990, 29, 216.
(4) Dias, H. V. R.; Wang, Z. J . Am. Chem. Soc. 1997, 119, 4650.
(5) Drost, C.; Hitchcock, P. B.; Lappert, M. F.; Pierssens, L. J .-M.
Chem. Commun. 1997, 1141.
(6) Drost, C.; Hitchcock, P. B.; Lappert, M. F. Organometallics 1998,
17, 3838.
(7) J utzi, P.; Keitemeyer, S.; Neumann, B.; Stammler, H.-G. Orga-
nometallics 1999, 18, 4778.
(8) Veith, M.; Schu¨tt, O.; Huch, V. Angew. Chem. 2000, 112, 614;
Angew. Chem., Int. Ed. 2000, 39, 601.
(9) Leung, W.-P.; Kwok, W.-H.; Weng, L.-H.; Law, L. T. C.; Zhou, Z.
Y.; Mak, T. C. W. J . Chem. Soc., Dalton Trans. 1997, 4301.
(10) Akkari, A.; Byrne, J . J .; Saur, I.; Rima, G.; Gornitzka, H.;
Barrau, J . J . Organomet. Chem. 2001, 622, 190.
(11) Ayers, A. E.; Klapo¨tke, T. M.; Dias, H. V. R. Inorg. Chem. 2001,
40, 1000.
(13) Ding, Y.; Hao, H.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-
G. Organometallics 2001, 20, 4806.
(14) Ding, Y.; Ma, Q.; Uso´n, I.; Roesky, H. W.; Noltemeyer, M.;
Schmidt, H.-G. J . Am. Chem. Soc. 2002, 124, 8542.
(15) Satge´, J .; Massol, M.; Riviere, P. J . Organomet. Chem. 1973,
56, 1.
(12) Ding, Y.; Roesky, H. W.; Noltemeyer, M.; Schmidt, H.-G.; Power,
P. P. Organometallics 2001, 20, 1190.
(16) Bulten, E. J .; Noltes, J . G. Tetrahedron Lett. 1967, 1443.
10.1021/om0203328 CCC: $22.00 © 2002 American Chemical Society
Publication on Web 10/16/2002

Alkylgermanium(II)-Diketiminato Compounds
Organometallics, Vol. 21, No. 24, 2002 5217
F igu r e 1. Thermal ellipsoid plot (50%) of 5. Important
structural data are given in Table 1.
Sch em e 1
F igu r e 2. Thermal ellipsoid plot (50%) of 6. Important
structural data are given in Table 1.
than those of the starting material 1 (1.988(2) and
1.997(3) Å).12 Obviously, this results from the influence
of the substituents at the metal center (the stronger
electron-withdrawing property of chlorine compared to
the alkyl groups). The Ge-C bond lengths in 5 (2.002-
(4) Å) and in 6 (2.014(3) Å) are in the normal range
(1.962(6)-2.039(3) Å).7
Der iva tives of Com p ou n d 5 a n d Th eir Str u c-
tu r es. Chalcogen derivatives of the heavier group 14
elements MdE (M ) Si, Ge, Sn; E ) S, Se, Te) usually
are prepared by reaction of the divalent group 14
compound with elemental chalcogens.18-23 Compound
5 reacts with elemental sulfur in toluene at reflux to
give the compound [HC(CMeNAr)2]GeMe(S) (7) (Scheme
2). By a similar procedure, the selenium analogue [HC-
(CMeNAr)2]GeMe(Se) (8) was prepared (Scheme 2) in
87% yield. However, alkylation of a halogen-containing
Ge(IV) sulfide also is a possible route to X(R)GedS
compounds. We recently synthesized the compound
[HC(CMeNAr)2]GeCl(S) (11),14 a species with a formal
double bond between the group 14 and 16 elements.
Thus 11 was treated with MeLi to afford 7 (Scheme 2).
To our surprise the GedS double bond in 7 remained
intact in the presence of the small methyl group.
Usually sterically bulky substituents are required for
a stable X(R)GedS compound.
Of special interest is the nature of the germanium-
chalcogenido interaction in 7 and 8, which may be
described by the resonance structures Ge+-E- T GedE.
This behavior of the GedS bond is supported by the
reaction products using Tbt(Tip)GedS (Tbt ) 2,4,6-tris-
[bis(trimethylsiyl)methyl]phenyl, Tip ) 2,4,6-triisopro-
pylphenyl) and reagents such as water and dienes.22 To
obtain more information about the germanium-sele-
Resu lts a n d Discu ssion
Syn th esis a n d Str u ctu r es of Com p ou n d s 5 a n d
6. Although Ge(II) compounds are generally reactive
and tend to oligomerize or polymerize, the preparation
of a series of novel monomeric â-diketiminato germa-
nium(II) compounds, [HC(CMeNAr)2]GeX (Ar ) 2,6-
iPr2C6H3; X ) Cl (1), F (2)),12,13 as well as [HC(CMeNAr)2]-
GeX(S) (X ) F (3), Cl (4)), might suggest that the
synthesis of a monomeric alkylated Ge(II) compound
would be possible. Therefore, compound 1 was treated
with MeLi and nBuLi in diethyl ether at -78 °C. After
workup, the compounds [HC(CMeNAr)2]GeR (R ) Me
(5), nBu (6)) were isolated in high yield (Scheme 1).
Compounds 5 and 6 are stable under an inert atmo-
sphere at temperatures below their melting points. They
are soluble in common organic solvents such as pentane,
diethyl ether, and dichloromethane.
For structural investigation, single crystals of 5 (red-
orange) and 6 (deep red) were crystallized from hexane
solution at -32 °C. The structures, determined by
single-crystal X-ray diffraction, are shown in Figures 1
and 2. Selected bond lengths and angles are listed in
Table 2; complete bond distances and angles are in-
cluded in the Supporting Information.
The observed structures of 5 and 6 show that both
compounds are monomeric, as expected, and that the
germanium centers adopt similar three-coordinate sites.
The sum of the bond angles at the metal center (280.81°
in 5 and 285.4° in 6) deviates strongly from that for
tetrahedral symmetry. The Ge-N bond lengths in 5
(2.008(2) and 2.038(2) Å) and in 6 (2.023(2) and 2.025-
(2) Å) are in the normal range2,3,17 but are slightly longer
(18) For the most recent reviews: (a) Power, P. P. Chem. Rev. 1999,
99, 3463. (b) Tokitoh, N.; Okazaki, R. Adv. Organomet. Chem. 2001,
47, 121.
(19) Kuchta, M. C.; Parkin, G. J . Chem. Soc., Chem. Commun. 1994,
1351.
(20) Ossig, G.; Meller, A.; Bro¨nneke, C.; Mu¨ller, O.; Scha¨fer, M.;
Herbst-Irmer, R. Organometallics 1997, 16, 2116.
(21) Foley, S. R.; Bensimon, C.; Richeson, D. S. J . Am. Chem. Soc.
1997, 119, 10359.
(22) Matsumoto, T.; Tokitoh, N.; Okazaki, R. J . Am. Chem. Soc.
1999, 121, 8811.
(23) Leung, W.-P.; Kwok, W.-H.; Zhou, Z.-Y.; Mak, T. C. W. Orga-
nometallics 2000, 19, 296.
(17) (a) Veith, M.; Detemple, A.; Huch, V. Chem. Ber. 1991, 124,
1135. (b) Barrau, J .; Rima, G.; El Amraoui, T. J . Organomet. Chem.
1998, 570, 163.

5218 Organometallics, Vol. 21, No. 24, 2002
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p ou n d s 5, 6, 8, a n d 9
Ding et al.
5
6
8
9
formula
fw
C
30H44GeN2
C
33H50GeN2
C
30H44GeN2Se
C33H53GeN3Si
592.46
505.26
547.34
584.22
color
orange-red
monoclinic
P21/c
17.230 (3)
13.211 (3)
13.323 (2)
109.011 (15)
2867.2 (9)
4
deep red
orthorhombic
Fdd2
22.679 (5)
63.773 (13)
8.7734 (18)
90
12689 (4)
16
yellow
monoclinic
P21/n
13.285 (3)
17.014 (3)
13.752 (3)
106.01 (3)
2987.8 (11)
4
pale yellow
monoclinic
P21/m
cryst syst
space group
a (Å)
b (Å)
c (Å)
8.782 (2)
19.962 (4)
10.500 (2)
114.58 (3)
1673.9 (6)
2
1.175
0.975
636
â (deg)
V (Å3)
Z
dcalcd (g cm-3
)
1.170
1.087
1080
1.146
0.987
4704
1.299
2.263
1216
µ (mm-1
F(000)
)
cryst size (mm)
2θ range (deg)
index range
1.00 × 0.60 × 0.30
7.04-45.08
-15 e h e 18,
-14 e k e 7,
-14 e l e 14
3944
3748 (R(int) ) 0.0637)
0.0388, 0.0986
0.0432, 0.1028
1.026
0.50 × 0.4 × 0.3
12.34-49.90
-26 e h e 25,
-74 e k e 74,
-10 e l e 9
21 238
4647 (R(int) ) 0.0613)
0.0310, 0.0761
0.0321, 0.0765
1.092
0.80 × 0.80 × 0.60
7.56-50.08
-15 e h e 15,
-9 e k e 20,
-16 e l e 16
8626
5267 (R(int) ) 0.0699)
0.0339, 0.0879
0.0384, 0.0916
1.028
0.60 × 0.50 × 0.40
4.72-55.36
-11 e h e 7,
-26 e k e 26,
-12 e l e 13
23 957
4004 (R(int) ) 0.0586)
0.0340, 0.0860
0.0392, 0.0900
1.026
no. of rflns collected
no. of indep rflns
R1, wR2 (I > 2(σ)I)
R1, wR2 (all data)
goodness of fit, F2
no. of data/restraints/params
abs structure param
largest diff peak and hole, e Å-3
3748/0/309
4647/1/336
0.047(9)
0.710, -0.493
5267/0/318
4004/16/213
0.601, -0.519
0.820, -0.633
0.459, -0.586
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for Com p ou n d s 5, 6, a n d 8
bond dist
bond angle
complex
5
Ge(1)-N(1) 2.008(2) N(1)-Ge(1)-N(2)
Ge(1)-N(2) 2.038(2) N(1)-Ge(1)-C(6)
Ge(1)-C(6) 2.002(4) N(2)-Ge(1)-C(6)
90.87(9)
97.13(13)
92.81(12)
6
8
Ge(1)-N(1) 2.023(2) N(1)-Ge(1)-N(2)
Ge(1)-N(2) 2.025(2) N(1)-Ge(1)-C(6)
87.85(9)
97.52(10)
Ge(1)-C(6) 2.014(3) N(2)-Ge(1)-C(6) 100.06(10)
Ge(1)-N(1) 1.931(2) N(1)-Ge(1)-N(2)
95.24(8)
Ge(1)-N(2) 1.947(2) Se(1)-Ge(1)-N(1) 113.38(6)
Ge(1)-C(6) 1.973(2) Se(1)-Ge(1)- -N(2) 117.15(6)
Ge(1)-Se(1) 2.1992(5) Se(1)-Ge(1)-C(6) 120.94(10)
N(1)-Ge(1)-C(6) 103.64(11)
N(2)-Ge(1)-C(6) 102.70(10)
Sch em e 2
F igu r e 3. Thermal ellipsoid plot (50%) of 8. Important
structural data are given in Table 1.
coordinate in a distorted-tetrahedral environment. This
geometry is similar to that of its sulfur analogue and
to those of the compounds containing a terminal chal-
cogenido germanium unit.14,19-23 The observed Ge-Se
bond length in 8 (2.199(1) Å), which is shorter than the
Ge-Se single-bond lengths in [Tbt(Mes)GeSe]2 (Mes )
2,4,6-trimethylphenyl) (2.397(1) and 2.433(1) Å),22 is in
good agreement with those reported for GedSe (2.180-
(2)22 to 2.247(7) Å20). The short Ge-Se bond length in 8
is indicative of a double bond or a Ge-Se σ bond with
an additional percentage of ionic character. The Ge-N
(1.931(2) and 1.947(2) Å) and Ge-C (1.973(2) Å) bond
lengths are shorter than those of the starting material
5 (Ge(1)-N(1) ) 2.008(2) Å, Ge(1)-N(2) ) 2.038(2) Å,
and Ge(1)-C(6) ) 2.002(4) Å), as expected from the
higher oxidation state of the product. The fact that the
N(1)-Ge(1)-N(2) angle of 8 (95.24(8)°) is larger than
that of 5 (90.87(9)°) may be explained in the same way.
nium interaction, the structure of compound 8 was
determined by single-crystal X-ray diffraction.
Figure 3 shows its molecular structure. Compound 8
is monomeric, and the germanium center is four-
77Se NMR may act as a good probe for the germa-
nium-selenium interaction. The 77Se chemical shift for
the Ge-Se single bond in (H3Ge)2Se is -612 ppm

Alkylgermanium(II)-Diketiminato Compounds
Organometallics, Vol. 21, No. 24, 2002 5219
Sch em e 3
F igu r e 4. Thermal ellipsoid plot (50%) of the molecular
backbone of 9. H atoms are not shown. Important struc-
tural data are given in Table 1.
(relative to Me2Se).24 In contrast, to the best of our
knowledge, the available data for germanium selenones,
R2GedSe, show resonances at a much lower field (800-
1100 ppm).20,22,23 In the 77Se NMR of compound 8 the
resonance was observed at -349 ppm. This finding that
the 77Se chemical shift for 8 (-349 ppm) is between that
for a single bond (-600 ppm) and those for a double
bond (800-1100 ppm) indicates that the bonding in 8
is appropriately described as intermediate between
Ge+-E- and GedE resonance structures.
Sch em e 4
The reaction of germylenes with trimethylsiyl azide
has been studied and established as a route to com-
pounds containing the GedN double bond.3,17 However,
treatment of 5 with trimethylsilyl azide in hexane at
room temperature gave the Ge-N single-bonded com-
pound [HC(C(CH2)NAr)CMeNAr]GeMe(N(H)SiMe3) (9),
instead of [HC(CMeNAr)2]GeMe(NSiMe3) (Scheme 3).
The reaction proceeds with migration of a hydrogen
atom from a methyl group of the ligand backbone to the
nitrogen atom on silicon with formation of a methylene
group. The EI-MS spectrum showed the molecular ion
peak M+ (m/e 593) with the calculated isotopic pattern.
In the 1H NMR spectrum of 9 (toluene-d8) the reso-
nances clearly show the existence of NH (δ 0.25, b, 1
H) and the â-CH2 moiety (δ 3.22, s, 1 H and δ 3.86, s, 1
H). The IR (Nujol) NH absorption is observed at 3361
cm-1. The NH resonance and the IR stretching fre-
quency are comparable with those of compounds con-
taining a GeN(H)SiMe3 group.17 Although the mecha-
nism for the formation of 9 is unclear, a likely one is
given in Scheme 4.
To obtain more evidence for the formula of 9 given
above, pale yellow crystals of 9 were obtained from a
hexane solution at -32 °C and investigated by X-ray
diffraction analysis. The result shows that the molecule
lies on a crystallographic mirror plane, although only
parts of the structure fulfill this symmetry. Refinement
in the lower symmetric space group P21 shows the same
disorder and no improvement. Due to this disorder, the
affected bond lengths are not very accurate and will not
be discussed here. Nevertheless, some important struc-
tural information for 9 was generated. Crystallographic
data for 9 are listed in Table 1. The molecular frame-
work of 9 is shown in Figure 4. It is monomeric in the
solid state, and the germanium is four-coordinate. The
hydrogen bond to N3 could clearly be found in the
electron density map. These findings, despite the dis-
order, as well as the results of NMR, IR, EI-MS, and
elemental analysis, support the formula given for 9.
The oxidative addition reaction of MeI with 5 in
dichloromethane afforded [HC(CMeNAr)2]GeMe2(I) (10)
(Scheme 3). Compound 10 is poorly soluble in THF and
has a high melting point (217-219 °C) compared to that
of the starting material 5.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All manipulations were carried
out using standard Schlenk techniques or in a glovebox under
a nitrogen atmosphere. Diethyl ether and toluene were freshly
distilled from Na and hexane from K prior to use. Elemental
analyses were performed by the Analytisches Labor des
Instituts fu¨r Anorganische Chemie der Universita¨t Go¨ttingen.
1
A Bruker AM 200 instrument was used to record H, 29Si, and
77Se NMR spectra (200.1 MHz), with reference to TMS, TMS,
and Me2Se, respectively. IR spectra were recorded on a Bio-
Rad Digilab FTS-7 spectrometer as Nujol mulls between KBr
(24) McFahrlane, H. C. E.; McFarlane, W. In Multinuclear NMR;
Mason, J ., Ed.; Plenum Press: New York, 1987; p 417.

5220 Organometallics, Vol. 21, No. 24, 2002
Ding et al.
plates. Mass spectra were obtained on a Finnigan Mat 8230
instrument. The compound [HC(CMeNAr)2]GeCl12 was pre-
pared by literature procedures. Other chemicals were pur-
chased from Aldrich and used as received.
which time the color changed from orange-red to pale yellow.
Concentration (ca. 10 mL) and storage of the solution in a -32
°C freezer for 24 h afforded yellow crystals of 9 (yield 0.362 g,
61%). Mp: 188-191 °C. Anal. Calcd for C33H53GeN3Si: C,
66.90; H, 9.02; N, 7.09. Found: C, 66.85; H, 9.09; N, 7.19. EI-
MS: m/e 593 (M+), 578 (M+ - Me, 100). 1H NMR (toluene-d8):
δ -0.36 (s, 9 H, SiMe3), 0.25 (s, 1 H, NH), 0.79 (s, 3 H, GeMe),
1.25 -1.50 (m, 24 H, CHMe2), 1.58 (s, 3 H, â-Me), 3.22 (s, 1 H,
â-CH2), 3.40 (sept, 2 H, CHMe2), 3.50 (sept, 2 H, CHMe2), 3.75
(sept, 2 H, CHMe2), 3.85 (sept, 2 H, CHMe2), 3.86 (s, 1 H,
â-CH2), 5.25 (s, 1 H, γ-CH), 7.10-7.20 (m, 6 H, 2,6-iPr2C6H3).
29Si NMR (toluene-d8): δ 5.94. IR (Nujol): 3361 cm-1 (NH).
[HC(CMeNAr )2]GeMe2(I) (Ar ) 2,6-iP r 2C6H3; 10). A
solution of MeI (0.142 g, 0.1 mmol) in dichloromethane (10 mL)
was added to a stirred solution of 5 (0.506 g, 1.0 mmol) in
dichloromethane (20 mL) at room temperature. After the
addition the reaction mixture was stirred for 10 h, during
which time the color changed from orange-red to yellow.
Removing the volatiles, washing the residue with n-hexane
(2 × 5 mL), and drying under vacuum afforded a pale yellow
powder of 10 (0.589 g, 91%). Mp: 217-219 °C. Anal. Calcd
for C31H47GeIN2 (647.2): C, 57.53; H, 7.32; N, 4.33. Found:
[HC(CMeNAr )2]GeMe (Ar ) 2,6-iP r 2C6H3; 5). A solution
of MeLi (1.4 mL, 1.6 M in diethyl ether, 2.24 mmol) was added
dropwise to a stirred solution of [HC(CMeNAr)2]GeCl (1; 1.05
g, 2.0 mmol) in diethyl ether (40 mL) at -78 °C. The reaction
mixture was warmed to room temperature and was stirred for
3 h. After removal of all volatiles, the residue was extracted
with n-hexane (30 mL). Storage of the extract in a -32 °C
freezer for 3 days afforded orange-red crystals of 5 (0.90 g,
89%). Mp: 131-132 °C. Anal. Calcd for C30H44GeN2 (506.3):
C, 71.31; H, 8.78; N, 5.54. Found: C, 71.56; H, 8.84; N, 5.53.
1
EI-MS (70 eV): m/e (%) 506 (M+, 5), 491 (M+ - Me, 100). H
NMR (C6D6): δ 0.64 (s, 3 H, GeMe), 1.16 (d, 6 H, CHMe2), 1.17
(d, 6 H, CHMe2), 1.29 (d, 6 H, CHMe2), 1.38 (d, 6 H, CHMe2),
1.55 (s, 6 H, â-Me), 3.45-3.50 (sept, 2 H, CHMe2), 3.65-3.73
(sept, 2 H, CHMe2), 4.80 (s, 1 H, γ-CH), 7.10-7.15 (m, 6 H,
2,6-iPr2C6H3).
[HC(CMeNAr )2]Gen Bu (Ar ) 2,6-iP r 2C6H3; 6). Deep red
crystals of 6 can be obtained in a way similar to that for 5 in
high yield (85%). Mp: 152-155 °C. Anal. Calcd for C33H50
-
C, 57.66; H, 7.13; N, 4.58. EI-MS (70 eV): m/e (%) 521 (M+
-
1
GeN2 (547.3): C, 72.41; H, 9.21; N, 5.12. Found: C, 72.01; H,
I, 20), 505 (M+ - I - CH4, 100). H NMR (CD3CN): δ 0.83 (s,
6 H, GeMe2), 1.19 (d, 12 H, CHMe2), 1.28 (d, 12 H, CHMe2),
2.02 (s, 6 H, â-Me), 2.80-3.00 (sept, 4 H, CHMe2), 5.85 (s, 1
H, γ-CH), 7.38-7.50 (m, 6 H, 2,6-iPr2C6H3).
9.10; N, 5.01. EI-MS (70 eV): m/e (%) 547 (M+, 5), 491 (M+
-
1
nBu, 100). H NMR (C6D6): δ 0.65 (t, 3 H, (CH2)3Me), 0.80-
1.05 (m, 6 H, (CH2)3Me), 1.12 (d, 6 H, CHMe2), 1.16 (d, 6 H,
CHMe2), 1.35 (d, 6 H, CHMe2), 1.42 (d, 6 H, CHMe2), 1.52 (s,
6 H, â-Me), 3.45-3.60 (sept, 2 H, CHMe2), 3.65-3.82 (sept, 2
H, CHMe2), 4.72 (s, 1 H, γ-CH), 7.05-7.15 (m, 6 H, 2,6-
iPr2C6H3).
X-r a y Cr ysta llogr a p h y. Single crystals of 5, 6, 8, and 9
were taken from the flask under nitrogen gas and mounted
on a glass fiber in a rapidly cooled perfluoropolyether.25 Data
were collected on a Stoe AED2 four-circle diffractometer (5 and
8) at 200(2) K or on a Stoe-Siemens-Huber four-circle diffrac-
tometer (6 and 9) equipped with a Siemens SMART area
detector at 133(2) K. Monochromated Mo KR radiation (λ )
0.710 73 Å) was used. The structures were solved by direct
methods (SHELXS-9626) and refined against F2 using SHELXL-
97.27 All non-hydrogen atoms were refined anisotropically. All
hydrogen atoms bonded to carbon were included in geo-
metrically ideal positions and refined with the riding model.
The hydrogen atom bonded to nitrogen (9) was refined with a
distance restraint. All disordered groups were refined with
distance restraints and restraints for the anisotropic displace-
ment parameters.
[HC(CMeNAr )2]GeMe(S) (Ar ) 2,6-iP r 2C6H3; 7). A solu-
tion of 5 (0.506 g, 1.0 mmol) in toluene (20 mL) was added to
a stirred suspension of elemental sulfur (0.032 g, 1.0 mmol)
and the mixture refluxed for 4 h. After removal of the volatiles,
the residue was washed with n-hexane (2 × 5 mL) and then
extracted with toluene (15 mL). Adding n-hexane (5 mL) to
the extract and keeping the solution at room temperature for
3 days afforded pale yellow crystals of 7 in a yield of 65%. The
physical data are in agreement with those in ref 14.
[HC(CMeNAr )2]GeMe(Se) (Ar ) 2,6-iP r 2C6H3; 8). A solu-
tion of 5 (0.506 g, 1.0 mmol) in toluene (20 mL) was added to
a stirred suspension of elemental selenium (0.079 g, 1.0 mmol)
in toluene (10 mL) at room temperature. The reaction mixture
was stirred for 2 days. After filtration a yellow solution was
obtained. Concentration (ca. 10 mL) and storage of the yellow
solution in a -32 °C freezer for 24 h afforded yellow crystals
of 8 (yield 0.508 g, 87%). Mp: 210-213 °C dec. Anal. Calcd
for C30H44GeN2Se: C, 61.67; H, 7.58; N, 4.79. Found: C, 61.29;
H, 7.47; N, 4.80. EI-MS: m/e 584 (M+), 569 (M+ - Me), 506
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der
Chemischen Industrie.
Su p p or tin g In for m a tion Ava ila ble: Figures showing
ORTEP diagrams and tables giving full details of the crystal-
lographic data and data collection parameters, atom coordi-
nates, bond distances, bond angles, anisotropic thermal pa-
rameters, and hydrogen coordinates for 5, 6, and 8. This
material is available free of charge via the Internet at
http://pubs.acs.org.
1
(M+ - Se). H NMR (C6D6): δ 1.06 (d, 6 H, CHMe2), 1.09 (d, 6
H, CHMe2), 1.10 (s, 3 H, GeMe), 1.25 (d, 6 H, CHMe2), 1.46 (s,
6 H, â-Me), 1.63 (d, 6 H, CHMe2), 2.92-3.02 (sept, 2 H,
CHMe2), 3.80-3.90 (sept, 2 H, CHMe2), 4.81 (s, 1 H, γ-CH),
7.01-7.15 (m, 6 H, 2,6-iPr2C6H3). 77Se NMR (C6D6): δ -349.
[HC(C(CH2)NAr )CMeNAr ]GeMe(N(H)SiMe3) (Ar ) 2,6-
iP r 2C6H3; 9). A solution of Me3SiN3 (0.106 g, 0.1 mmol) in
n-hexane (10 mL) was added to a stirred solution of 5 (0.506
g, 1.0 mmol) in n-hexane (20 mL) at room temperature. After
the addition, the reaction mixture was stirred for 12 h, during
OM0203328
(25) Kottke, T.; Stalke, D. J . Appl. Crystallogr. 1993, 26, 615.
(26) Sheldrick, G. M. Acta Crystallogr., Sect. A 1990, 46, 467.
(27) Sheldrick, G. M. SHELXL-97; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1997.