Germylenes and germyl cations with the 2,4-Di-tert-butyl-6-(N,N-dimethylaminomethyl)phenyl ligand

Article abstract of DOI:10.1021/om980156w

The 2,4-di-tert-butyl-6-(N,N-dimethylaminomethyl)phenyl (Mamx) ligand allows the synthesis of the germylenes MamxGeCl (1), Mamx₂Ge (2), Mamx-(Tip)Ge (3; Tip = 2,4,6-iPr₃C₆H₂), MamxGeN₃ (4), MamxGeN(SiMe₃)₂ (5), and MamxGe[Fe(CO)₂Cp*] (6), which are all stabilized by coordination of the amino side chain. Reactions of 2 and 3 with MeI yield the ionic compounds Mamx(Tip)(Me)Ge⁺I^- (7) and Mamx₂(Me)-Ge⁺I^- (8), respectively; the X-ray crystal structure of 7 shows a trigonal-planar coordination at the Ge center and a nearly perpendicular Ge-N bond.

Full text of DOI:10.1021/om980156w

Organometallics 1998, 17, 2149-2151
2149
Ger m ylen es a n d Ger m yl Ca tion s w ith th e
,4-Di-ter t-bu tyl-6-(N,N-d im eth yla m in om eth yl)p h en yl
Liga n d
2
Holger Schmidt, Silke Keitemeyer, Beate Neumann, Hans-Georg Stammler,
Wolfgang W. Schoeller, and Peter J utzi*
Faculty of Chemistry, University of Bielefeld, Universit a¨ tstrasse, D-33615 Bielefeld, Germany
Received March 4, 1998
Summary: The 2,4-di-tert-butyl-6-(N,N-dimethylami-
nomethyl)phenyl (Mamx) ligand allows the synthesis of
the germylenes MamxGeCl (1), Mamx2Ge (2), Mamx-
solubility in THF and in toluene. In Et2O as the solvent,
1 cocrystallizes with 18-crown-6; the molecular struc-
ture of 1 is presented in Figure 1.
4
(
Tip)Ge (3; Tip ) 2,4,6-iPr3C6H2), MamxGeN3 (4),
The first experiments demonstrate that 1 is a suitable
substrate for the preparation of the homoleptic, mono-
meric germylene Mamx2Ge (2) and further preparation
of heteroleptic germylenes with inorganic, organic, and
organometallic substituents. Treatment of GeCl2‚-
dioxane with 2 equiv of MamxLi in THF at -80 °C leads
MamxGeN(SiMe3)2 (5), and MamxGe[Fe(CO)2Cp*] (6),
which are all stabilized by coordination of the amino side
chain. Reactions of 2 and 3 with MeI yield the ionic
+
-
compounds Mamx(Tip)(Me)Ge I (7) and Mamx2(Me)-
+
-
Ge I (8), respectively; the X-ray crystal structure of 7
shows a trigonal-planar coordination at the Ge center
and a nearly perpendicular Ge-N bond.
5
to the formation of pale green 2. In the solid state,
only one of the two amino groups coordinates to the
In compounds with low-energy vacant orbitals, sub-
stituents with donor groups in the side chain and with
suitable geometry lead to intramolecular coordination
and consequently to drastic changes in structure and
reactivity as compared to the parent species. In the
chemistry of germanium, this is documented mainly by
6
germanium center. As NMR spectra show, the side
7
chains exchange their positions in solution. This
8
process is quite fast at 80 °C; at -80 °C the dynamic
behavior of 2 is “frozen” on the NMR time scale.9 The
pale green diarylgermylene Mamx(Tip)Ge (3) is pre-
pared analogously by reaction of 1 with 2,4,6-triisopro-
1
some recent examples. The title ligand, abbreviated
1
0
pylphenyllithium.
Crystals suitable for an X-ray
Mamx (methylaminomethyl-m-xylyl), was first synthe-
sized by Yoshifuji et al. and successfully applied in the
chemistry of low-coordinated phosphorus.2 We have
tested this ligand in germanium chemistry and present
here the first results concerning the synthesis and
characterization of monomeric germanium(II) com-
pounds (germylenes) and of ionic germanium(IV) species
with novel features of structure and bonding.
(4) Colorless crystals of 1 and 18-crown-6 in a ratio of 2:1; no
intermolecular coordination to the Ge center is found. Crystallographic
data: C23
3 1
H40ClGeNO , monoclinic, space group P2 /c, a ) 14.2815(7)
Å, b ) 9.8468(5) Å, c ) 18.9434(10) Å, â ) 101.3290(10)°, V ) 2612.0-
3
-3
-1
(2) Å , Z ) 4, D
c
) 1.237 g cm , µ ) 1.296 mm , T ) 183(2) K, 22 940
reflections collected, 5693 unique reflections, R indices (all data) R1
)
0.0320, wR2 ) 0.0626, GOF ) 1.044. Full details of the crystal-
lographic analyses of 1, 3, and 7 are described in the Supporting
2
Information.
(
246 (73, Mamx
Reaction of MamxLi with GeCl2‚dioxane in THF in
5) 2: MS (CI), [m/z (Irel)]: 567 (30, M+ + H), 320 (100, MamxGe ),
+
a 1:1 ratio leads nearly quantitatively to MamxGeCl
+
56 2
). Mp: 105 °C. Anal. Calcd for C34H N Ge: C, 72.22;
3
H, 10.02; N, 4.95. Found: C, 72.14; H, 10.15; N, 4.24.
(
1), which is isolated as a colorless powder with good
(
6) Unpublished results.
1
(7) 2: H NMR (toluene-d
8
, 25 °C) δ 1.38 (s, 18 H, tBu), 1.85 (br, 30
), 7.62 (br, 4 H, aryl-H).
, 80 °C) δ 1.35, 1.75 (2 s, 18 H, tBu), 1.81
HH ) 14 Hz, 2 H, CH ), 3.65 (br d, 2 H,
*
To whom correspondence should be addressed. E-mail:
peter.jutzi@uni-bielefeld.de.
1) (a) Veith, M.; Hobein, P.; R o¨ sler, R. Z. Naturforsch. 1989, 44b,
067. (b) Veith, M.; Becker, S.; Huch, V. Angew. Chem. 1989, 101, 1287.
c) Karsch, H. H. J . Organomet. Chem. 1988, 344, 153. (d) Karsch, H.
H, tBu + NCH
(8) 2: H NMR (toluene-d
3
), 3.05 (br 4 H, CH
2
1
8
2
(
(s, 12 H, NCH
CH ), 7.21 (br s, 2 H, aryl-H), 7.53 (s, 2 H, aryl-H). C NMR (toluene-
), 34.92, 38.83 (C(CH ), 47.70
), 122.30, 149.76 (aryl-C).
3
), 3.12 (d,
J
2
1
3
1
2
(
d
8
, 80 °C): δ 31.87, 34.05(C(CH
3
)
3
3 3
)
H. Russ. Chem. Bull. 1993, 42, 1937 and references cited herein. (e)
J utzi, P.; Schmidt, H.; Neumann, B.; Stammler, H.-G. J . Organomet.
Chem. 1995, 499, 7. (f) Barrau, J .; Rima, G.; Amraoui, T. E. Inorg.
Chim. Acta 1996, 241, 9. (g) Foley, S. R.; Bensimon, C.; Richeson, D.
S. J . Am. Chem. Soc. 1997, 119, 10359. (h) Ossig, G.; Meller, A.;
Br o¨ nneke, C.; M u¨ ller, O.; Sch a¨ fer, M.; Herbst-Irmer, R. Organometal-
lics 1997, 16, 2116. (i) 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,
(NCH
3
), ∼68 (CH
2
1
(9) 2: H NMR (toluene-d
1.49, 1.83 (3 s, 9 H, tBu), 1.96 (s, 6 H, NCH
8
, -80 °C) δ 1.34 (m, 6 H, NCH
3
), 1.45,
), 2.09 (s, 9 H, tBu), 2.57,
3
2
3.14, 3.27, 3.75 (4 d, J HH ) 14 Hz, 1 H, CH
2
), 6.93, 7.56, 7.82, 7.94 (4
1
3
s, 1 H, aryl-H). C NMR (toluene-d
8
, -80 °C): δ 31.52, 31.63, 32.28,
),
), 118.28, 121.22, 121.84, 122.27, 141.59, 146.72,
148.86, 149.14, 152.02, 154.66, 158.24, 158.58 (aryl-C).
34.60, 34.80, 34.89, 37.55, 39.57 (tBu), 45.33, 46.65, 48.11 (NCH
65.25, 69.56 (CH
3
2
1
4
301. (j) Drohst, C.; Hitchcock, P. B.; Lappert, M. F.; Pierssens, L. J .-
(10) 3: H NMR (C
H, tBu), 1.51 (d,
CH(CH
6
D
6
) δ 1.01, 1.28 (2 m, 6 H, CH(CH
HH ) 7 Hz, 3 H, CH(CH ), 1.63 (m, 12 H, tBu +
), 1.90, 2.02, (2 s, 3 H, NCH ), 2.85 (p-sep, (pseudo-sep), J HH
), 2.92 (d, J HH ) 13 Hz, 1 H, CH ), 3.20 (p-sep,
HH ) 13 Hz, 1, H, CH ), 5.13
), 7.02, 7.10, 7.29, 7.53 (4 s, 1 H,
): δ 23.03, 24.33, 25.99, 26.25 27.26 (iPr), 31.69
), 32.08 (iPr), 32.80 (C(CH ), 33.30, 34.70 (iPr), 38.00
), 46.66, 47.75 (NCH ), 70.26 (NCH ), 118.42, 121.27, 121.29,
3 2
) ), 1.37 (s, 9
3
M. J . Chem. Soc., Chem. Commun. 1997, 1141. (k) Karsch, H. H.;
Schl u¨ ter, P. A.; Reisky, M. Eur. J . Inorg. Chem. 1998, 433.
J
3 2
)
3
3
)
2
3
2
(
2) Yoshifuji, M.; Kamijo, K.; Toyota, K. Tetrahedron Lett. 1994, 35,
971.
3) 1: H NMR (C
.25 (2 s, 3 H, NCH
.49 (2 s, 1 H, aryl-H). C NMR (C
), 34.86, 37.87 (C(CH ), 43.37, 45.26 (NCH
18.49, 121.45 (tert aryl-C), 144.77, 150.98, 156.19, 157.05 (quart aryl-
) 7 Hz, 1 H, CH(CH
3
)
2
2
3
2
3
J
HH ) 7 Hz, 1 H, CH(CH
3
)
2
), 4.04 (d,
HH ) 7 Hz, 1 H, CH(CH
13
J
2
1
3
(
6
D
6
, 500.1 MHz) δ 1.32, 1.60 (2 s, 9 H, tBu), 1.64,
(p-sep,
J
3 2
)
2
2
7
(
3
), 2.88, 4.50 (2 d,
J
HH ) 14 Hz, 1 H, CH
, 125.75 MHz): δ 31.57, 33.75
), 67.62 (NCH ),
2
), 6.96,
6 6
aryl-H). C NMR (C D
(C(CH
(C(CH
1
3
6
D
6
3
)
)
3
3 3
)
C(CH
3
)
3
3
)
3
3
2
3
3
3
2
1
121.60 (tert aryl-C), 142.35, 147.55, 148.66, 149.25, 155.81, 156.08,
+
+
+
C). MS (CI) [m/z (Irel)]: 355 (57, M ), 320 (100, MamxGe ). Mp: 164
C. Anal. Calcd for C17 28NClGe C, 57.59; H, 7.96; N, 3.95. Found: C,
6.44; H, 7.94; N, 3.60.
158.33, 158.51 (quart aryl-C). MS (CI), [m/z (Irel)]: 523 (86, M ), 320
+
°
5
H
(100, MamxGe ). Mp: 107 °C. Anal. Calcd for C32
H
51NGe: C, 73.58;
H, 9.84; N, 2.68. Found: C, 71.77; H, 10.13; N, 2.49.
S0276-7333(98)00156-3 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 05/08/1998

2
150 Organometallics, Vol. 17, No. 11, 1998
Communications
GeN(SiMe3)2 (5),14 and MamxGe[Fe(CO)2Cp*] (6)15 are
obtained from 1 by reaction with NaN3 in THF, with
LiN(SiMe3)2 in hexane, and with K[Fe(CO)2Cp*] in
hexane, respectively. They are all stable species under
ordinary conditions, with the exception of 4 which
decomposes slowly in solution. Coordination of the
amino group is generally observed, as indicated in the
NMR spectra by the existence of diastereotopic CH2
protons and methyl groups and a low-field shift of the
side chain signals.
Reaction of 3 with MeI in THF leads instantanously
1
6
to the colorless compound 7, which contains the
+
-
Mamx(Tip)(Me)Ge cation (7a ) and the counteranion I .
Crystals suitable for an X-ray structure analysis were
1
7
F igu r e 1. Molecular structure of 1, ORTEP plot (50%
probability). Selected bond lengths (Å) and angles (deg):
Ge-C(1), 2.0156(14); Ge-Cl, 2.3283(4); Ge-N, 2.0936(13);
C(1)-Ge-Cl, 94.04(4); C(1)-Ge-N, 83.09(5); Cl-Ge-N,
obtained from THF. The structure of 7a is shown in
Figure 3.
The closest Ge-I distance in the crystal is 5.16 Å,
which excludes any bonding interactions. In 7a , the
nearly perfect trigonal-planar arrangement of the GeC3
unit is of special interest; the angle sum is 352.15°. The
GeC3 plane and the NfGe bond vector form an angle
of 77°. The dihedral angle between the aromatic ring
plane of the Mamx ligand and the GeC3 plane is 72.1°.
A nearly perpendicular orientation (92.3°) is observed
between the two aromatic ring planes. The structural
features of 7a are novel in the chemistry of germanium
9
3.12(4).
1
8
cations. In an analogous fashion, the germylene 2 is
transferred to the ionic species Mamx2(Me)Ge I (8),
+
-
in which one of the amino groups remains uncoordi-
1
9
nated.
Interestingly, the methyl cation prefers to
attack the germanium and not the nitrogen lone pair
in 2, thus demonstrating the pronounced nucleophilicity
of the lone pair at the germanium atom.
F igu r e 2. Molecular structure of 3, ORTEP plot (50%
probability). Selected bond lengths (Å) and angles (deg):
Ge-C(1), 2.012(6); Ge-C(18), 2.084(6); Ge-N, 2.165(5);
C(1)-Ge-C(18), 104.2(2); C(1)-Ge-N, 80.3(2); C(18)-Ge-
N, 93.4(2).
1
(
14) 5: Colorless oil. H NMR (C
6
D
6
): δ -0.01, 0.56 (2 s, 9 H, SiCH
3
),
1
J
.34. 1.63 (2 s, 9 H, tBu), 1.82, 2.18 (2 s, 3 H, NCH
3
), 2.97, 4.06 (2 d,
2
13
HH ) 14 Hz, 1 H, CH
), 31.66, 33.39 (C(CH
), 69.07 (CH
50.59, 156.29, 156.67 (quart aryl-C). MS (CI), [m/z (Irel)]: 480 (1.3,
2
), 6.91, 7.45 (2 s, 1 H, aryl-H). C NMR (C
6
D
6
):
δ 5.80, 6.55 (SiCH
5.35, 45.93 (NCH
3
3
)
3
), 34.75, 38.08 (C(CH
3
)
3
),
4
1
3
2
), 118.63, 121.82 (tert aryl-C), 143.75,
+
+
+
M ), 465 (1.2, M - CH
3
), 320 (100, MamxGe ). Anal. Calcd for
crystal structure analysis11 were obtained from hexane;
the molecular structure of 3 is shown in Figure 2.
In the structures of 1 and 3, the geometry at the
germanium atom and the N-Ge bond length is worth
mentioning. The angle R (ipso-C-Ge-N) is smaller
than 90° in both compounds. The angle â (ipso-C-Ge-
R) is 94° in 1 and 104° in 3, and the angle γ (N-Ge-R)
is comparable (=93°). The NfGe donor bond is unex-
pectedly short in both compounds; the observed distance
C
23
H
46
N
2
GeSi : C, 57.61; H, 9.67; N, 5.84. Found: C, 57.87; H, 9.95;
2
N, 5.61.
(
15) 6: 1H NMR (C
Cp*), 2.16, 2.37 (2 s, 3 H, NCH ), 3.22, 4.78 (2 d,
6 6
D ) δ 1.32, 1.65 (2 s, 9 H, tBu), 1.68 (s, 15 H,
2
3
J
HH
) 14 Hz, 1 H,
1
3
CH
2
), 7.01, 7.54 (2 s, 1 H, aryl-H). C NMR (C
1.66, 32.56 (C(CH ), 34.58, 38.52 (C(CH ), 45.80, 48.72 (NCH
9.60 (CH ), 94.53 (C (CH
6
D
6
): δ 9.75 (C
5
(CH
3
)
5
),
),
3
6
3
)
3
3 3
)
3
2
5
3
)
5
), 117.95, 121.89 (tert aryl-C), 142.65,
148.69, 156.11, 163.47 (quart aryl-C), 219.72, 223.92 (CO). IR (Nujol,
cm ): 1952, 1939, 1888, 1877. MS (CI), [m/z (Irel)]: 509 (8.9, M+
-
1
-
+
+
+
4
C H10), 320 (74.6, MamxGe ), 246 (24.5, Mamx ), 203 (42.0, C15H23 ),
+
1
36 (100, Cp*H ). UV-Vis (hexane, nm): λmax 224 (ꢀ ) 24 000), 255 (ꢀ
) 16 000), 303 (ꢀ ) 9200). Mp: 148 °C. Anal. Calcd for C29
FeGe: C, 61.52; H, 7.65; N, 2.47. Found: C, 61.48; 7.68, 2.47.
H
2
43NO -
approaches that in covalent N-Ge(II) bonds (Me2Si-
1
3
(
16) 7: H NMR (C
6 6
D ) δ 0.66, 0.85 (2 d, J HH ) 7 Hz, 3 H, CH-
12
(
NtBu)(NtBuH)GeCl,1a 1.89 Å; ((Me3Si)2N)2Ge, 1.87
(CH ) ), 1.10, 1.20 (2 m, 12 H, tBu + CH(CH ) ), 1.57, 1.75 (2 d, J
3
3
2
3
2
HH
)
6 Hz, 3 H, CH(CH
CH(CH
H, NCH
3
)
2
), 1.96 (s, 3 H, GeCH
), 3.40 (s, 3 H, NCH ), 3.65 (p-sep, 1 H, CH(CH
HH ) 15 Hz, 1 H, CH ), 6.98, 7.21, 7.50,
): δ 12.08 (GeCH ), 23.67, 23.93,
), 31.70 (iPr), 32.25 (C(CH ),
), 35.48 (iPr), 36.61 (C(CH ), 47.33, 47.70
), 122.24, 123.32, 124.32 (tert aryl-C), 124.78 (quart
3
), 2.63, 2.92 (2 p-sep, 1 H,
and 1.88 Å).
3
)
2
3
3 2
)
), 3.83 (s, 3
The heteroleptic germylenes MamxGeN3 (4),13 Mamx-
2
3
), 4.03, 5.95 (2 d,
J
2
1
3
7
.61 (4 s, 1 H, aryl-H). C NMR (C
25.71, 27.06, 27.17 (iPr), 31.15 (C(CH
34.33 (iPr), 35.06 (C(CH
(NCH ), 67.31 (CH
6
D
6
3
(11) Crystallographic data for 3: C32
H
51GeN, triclinic, space group
3
)
3
3 3
)
P 1h , a ) 9.86(1) Å, b ) 10.04(1) Å, c ) 15.66(2) Å, R ) 97.42(8)°, â )
3
)
3
3 3
)
3
-3
9
1
6.45(9)°, γ ) 93.66(8)°, V ) 1524(3) Å , Z ) 2, D
c
) 1.138 g cm , µ )
3
2
.024 mm- , T ) 173(2) K, 4270 reflection collected, 3990 unique
1
aryl-C), 125.64 (tert aryl-C), 131.80, 140.73, 153.32, 154.72, 154.83,
+
+
reflections, R indices (all data) R1 ) 0.1055, wR2 ) 0.1302, GOF )
.035.
12) Chorley, R. W.; Hitchcock, P. B.; Lappert, M. F.; Leung, W.-P.;
Power, P. P.; Olmstead, M. M. Inorg. Chim. Acta 1992, 198-200, 203.
156.81, 158.18 (quart aryl-C). MS (CI, M ) Mamx(Tip)(CH
(Irel)]: 522 (55, M+ - CH ), 507 (100, M+ - C
Anal. Calcd for C33
3
)Ge ), [m/z
+
1
4
2
H
7
), 320 (20, MamxGe ).
(
H
54NGeI: C, 60.11; H, 7.49; N, 2.12. Found: C,
59.61; H, 8.42; N, 1.69.
(17) Colorless crystals of 7, containing 1 equiv of THF, which is not
coordinated to the Ge center. Crystallographic data: C37H62GeINO,
1
(
13) 4: Colorless solid. H NMR (C
.57, 2.05(2 s, 3 H, NCH ), 2.83, 4.07 (2 d,
.93, 7.48 (2 s, 1 H, aryl-H). C NMR (C
4.89, 37.59 (C(CH ), 43.73, 45.54 (NCH
6
D
6
): δ 1.31, 1.56 (2 s, 9 H, tBu),
2
1
6
3
3
J
HH ) 14 Hz, 1 H, CH
): δ 31.60, 33.63 (C(CH
), 68.20 (CH
2
),
),
1
3
6
D
6
3
)
3
triclinic, space group P 1h , a ) 12.6238(6) Å, b ) 12.6753(6) Å, c )
3
)
3
3
2
), 118.58, 121.16
13.2373/7) Å, R ) 81.066(1)°, â ) 68.145(1)°, γ ) 77.837(1)°, V ) 1914.8-
3
-3
-1
(tert aryl-C), 145.03, 151.43, 152.43, 157.24 (quart aryl-C). IR (Nujol):
c
(2) Å , Z ) 2, D ) 1.277 g cm , µ ) 1.632 mm , T ) 183(2) K, 18 255
1
2
072 cm- . Mp: 106 °C. Due to the instability in solution, crystalline
reflections collected, 8124 reflections unique, R indices (all data) R1
) 0.0829, wR2 ) 0.1056, GOF ) 1.075.
4
could not yet be obtained. Therefore, satisfactory analytical data are
not available.
(18) Belzner, J . Angew. Chem. 1997, 109, 1331.

Communications
Organometallics, Vol. 17, No. 11, 1998 2151
phenyl ring and the germanium and nitrogen atom) and
+
the donor-acceptor adducts of (b) NH3 with GeH3 and
+
(
c) N(CH3)3 with Ge(CH3)3 show that in cations of this
type a total charge of ca. 0.3 electrons is transferred
from N to Ge, creating a dative bond which is one-half
as strong as a single bond. The equilibrium bond
lengths are 2.01, 2.02, and 2.04 Å (for cases a, b, and
c), in close agreement with the experimentally found
value for 7a . Therefore, 7a has to be considered as a
base-stabilized germyl cation or a “germylium ion” and
not as a germyl-substituted ammonium ion. Calcula-
tions further verify that there is no significant interac-
tion between the Ge center and a methyl group in the
axial position, so the stabilizing effect of the ortho-tert-
butyl group has to be attributed merely to steric factors.
In germanium chemistry, the Mamx ligand combines
F igu r e 3. Structure of 7a , ORTEP plot (50% probability).
Selected bond lengths (Å) and angles (deg): Ge-C(1),
1
2
1
.961(4); Ge-C(18), 1.942(4); Ge-C(19), 1.975(4); Ge-N,
.034(3); C(1)-Ge-C(18), 117.27(18); C(1)-Ge-C(19),
17.36(17); C(18)-Ge-C(19), 117.52(19); C(1)-Ge-N, 86.44-
*
the steric properties of the Mes (2,4,6-tri-tert-butyl-
2
1
phenyl) ligand and the donor function of the 2-dim-
2
2
ethylaminomethylphenyl ligand. This behavior allows
the synthesis of so far unknown compounds with new
variants in structure and reactivity. Further investiga-
tions are in progress.
(15); C(18)-Ge-N, 104.65(17); C(19)-Ge-N, 106.65(16).
Quantum mechanical calculations20 at a density
functional level (b3lyp/6-31g*) on various model com-
pounds (a) parent 7a (without alkyl substitution at the
Ack n ow led gm en t. The financial support of the
“Deutsche Forschungsgemeinschaft” and the “Fonds der
Chemischen Industrie” as well as a gift of germanium
from Chemetall GmbH, Frankfurt/Main, is gratefully
acknowledged.
(
19) (a) 8: 1H NMR (C
H, GeCH ), 1.41 (s, 9 H, tBu), 1.42 (s, 6 H, NCH
Hz, 1 H, CH ), 2.93, 3.58 (2 s, 3 H, NCH ), 3.70 (d, J HH ) 12 Hz, 1 H,
CH ), 4.99, 6.02 (2 d, J HH ) 15 Hz, 1 H, CH ), 7.15, 7.49, 7.65, 7.86 (4
s, 1 H, aryl-H). C NMR (C ): δ 17.66 (GeCH ), 30.91, 31.35, 32.36,
), 34.80, 35.12, 36.91, 37.54 (C(CH ), 44.08 (NCH ),
0.74, 53.45 (NCH ), 65.93, 70.41 (CH ), 122.60, 124.66, 125.94, 129.72
6 6
D ) δ 1.09, 1.19, 1.30 (3 s, 9 H, tBu), 1.36 (s,
2
3
3
3
), 2.67 (d, J HH ) 12
2
2
3
2
2
2
1
3
6
D
6
3
3
5
4.52 (C(CH
3
)
3
3
)
3
3
3
2
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement, measurement and program
parameters, atomic coordinates and isotropic displacement
parameters, bond lengths and angles, anisotropic displacement
parameters, and hydrogen coordinates and isotropic displace-
ment parameters for 1, 3, and 7 and experimental procedures
for the synthesis of 1-8 (21 pages). Ordering information is
given on any current masthead page.
(
tert aryl-C), 132.68, 140.38, 146.06, 152.43, 153.67, 154.33, 158.25
+
+
(
M
quart aryl-C). MS (CI, M ) Mamx
2
(CH
3
)Ge ), [m/z (Irel)]: 579 (6.6,
+), 320 (45,
+
), 565 (21, M+ - CH
- H
2
+
4
), 335 (25, MamxGeCH
3
+
MamxGe ), 246 (100, Mamx ). Crystals containing 8 and 2 equiv of
THF could be isolated in traces. The structure of 8 was also confirmed
by an X-ray crystal analysis. Due to the poor quality of the crystals,
details of the structure will not be discussed in this paper.
(20) (a) All calculations were performed with the Gaussian set of
programs. Gaussian 94, Revision B.3: Frisch, M. J .; Trucks, G. W.;
Schlegel, H. B.; Gill, P. M. W.; J ohnson, B. G.; Robb, M. A.; Cheeseman,
J . R.; Keith, T.; Petersson, G. A.; Montgomery, J . A.; Raghavachari,
K.; Al-Laham, M. A.; Zakrzewski, V. G.; Ortiz, J . V.; Foresman, J . B.;
Peng, C. Y.; Ayala, P. Y.; Chen, W.; Wong, M. W.; Andres, J . L.;
Replogle, E. S.; Gomperts, R.; Martin, R. L.; Fox, D. J .; Binkley, J . S.;
Defrees, D. J .; Baker, J .; Stewart, J . P.; Head-Gordon, M.; Gonzalez,
C.; Pople, J . A. Gaussian, Inc.: Pittsburgh, PA, 1995. (b) For a general
discussion on donor-acceptor formation at silylene, germylene, and
stannylene, see: Schoeller, W. W.; Schneider, R. Chem. Ber. 1997, 130,
OM980156W
(21) (a) J utzi, P.; Leue, C. Organometallics 1994, 13, 2898. (b) J utzi,
P.; Schmidt, H.; Neumann, B.; Stammler, H.-G. Organometallics 1996,
15, 741.
(22) (a) Corriu, P.; Lanneau, G.; Priou, C.; Soulairol, F.; Auner, N.;
Probst, R.; Conlin, R.; Tan, C. J . Organomet. Chem. 1994, 466, 55. (b)
Belzner, J .; Sch a¨ r, D.; Kneisel, B. O.; Herbst-Irmer, R. 1995, 14, 1840.
1
013.