Azadigermiridines by addition of diazomethane or trimethylsilyldiazomethane to a digermene

Article abstract of DOI:10.1021/om990337d

Tetrakis(2,4,6-triisopropylphenyl)digermene (2), prepared by treatment of germanium bis(trimethylsilyl)amide with 2,4,6-triisopropylphenyllithium, reacts with diazomethane or trimethylsilyldiazomethane in a [2+1] fashion to furnish the N-methyleneamino-substituted azadigermiridines 7 and 8, respectively. The dissociation equilibrium between 2 and bis(triisopropylphenyl)germylene has been confirmed by the trapping reaction with a 1,2-quinone, from which the 1,3-dioxa-2-germaindan 10 was isolated. The structures of 2, 7, 8, and 10 were determined by X-ray crystallography. The sterically congested digermene 2 has a short Ge-Ge double-bond length of 2.213(1) A.

Full text of DOI:10.1021/om990337d

Organometallics 1999, 18, 3159-3163
3159
Aza d iger m ir id in es by Ad d ition of Dia zom eth a n e or
Tr im eth ylsilyld ia zom eth a n e to a Diger m en e1
Helmut Scha¨fer, Wolfgang Saak, and Manfred Weidenbruch*
Fachbereich Chemie der Universita¨t Oldenburg, Carl-von-Ossietzky-Strasse 9-11,
D-26111 Oldenburg, Germany
Received May 6, 1999
Tetrakis(2,4,6-triisopropylphenyl)digermene (2), prepared by treatment of germanium bis-
(trimethylsilyl)amide with 2,4,6-triisopropylphenyllithium, reacts with diazomethane or
trimethylsilyldiazomethane in a [2+1] fashion to furnish the N-methyleneamino-substituted
azadigermiridines 7 and 8, respectively. The dissociation equilibrium between 2 and bis-
(triisopropylphenyl)germylene has been confirmed by the trapping reaction with a 1,2-
quinone, from which the 1,3-dioxa-2-germaindan 10 was isolated. The structures of 2, 7, 8,
and 10 were determined by X-ray crystallography. The sterically congested digermene 2
has a short Ge-Ge double-bond length of 2.213(1) Å.
In tr od u ction
Resu lts a n d Discu ssion
Up to now the digermene 2 was mostly prepared in a
multistage procedure starting from a germanium tet-
rahalide.5,6 We have found that the reaction of the
germanium(II) amide 57 with the appropriate aryl-
lithium component affords compound 2 in one step and
the acceptable yield of 67% (Scheme 2).
Digermenes now constitute an established class of
compounds and have been the topic of several review
articles.2 One of their most interesting modes of reaction
involves formal [2+1] cycloaddition at the Ge/Ge double
bond to form digermiranes. The latter compounds,
consisting of a three-membered ring composed of two
germanium atoms and one heteroatom, are not readily
accessible by other routes (Scheme 1).
An X-ray crystallographic analysis (Figure 1) of the
light yellow crystals of 2 gave some unexpected results.
Thus, the Ge-Ge separation in 2 is 2.213(1) Å and thus
identical with the value found for the sterically ap-
preciably less congested compound 1 [2.213(2) Å].8 Also
the trans-bent and torsion angles of 12.3° and 13.7° are
comparable with those of 1 (12° and 10°, respectively).
These structural similarities are surprising because
digermenes have otherwise been found to react very
sensitively to changes in the spatial requirements of
their substituents. For example, the tetraaryldigermene
(Z)-Mes(Dip)GedGe(Dip)Mes, Mes ) 2,4,6-Me3C6H2,
Dip ) 2,6-iPr2C6H3, with appreciably less bulky sub-
stituents than 2 exhibits a much longer double-bond
length of 2.301(1) Å and a trans-bent angle of 36°.9
Together with 1, compound 2 has the shortest currently
observed Ge/Ge double-bond length, and this fact,
together with the steric shielding in 2, explains why the
expected [2+3] cycloaddition processes proceed only with
great difficulty.
For example, the 2,6-diethylphenyl-substituted di-
germene 1 reacts with diazomethane to furnish the
digermirane 3, presumably by way of a [2+3] cycload-
dition with subsequent elimination of nitrogen. Depend-
ing on the reaction conditions, compound 3 is isolated
in 72%3 or even quantitative yield.4 In contrast, the
corresponding reaction of the more voluminously sub-
stituted digermene 2 affords the digermirane 4 in only
6% yield.3 The increased steric shielding in 2 apparently
has an adverse effect on the primary [2+3] addition, and
thus, perhaps, a further mode of attack of diazomethane
on the Ge/Ge double bond needs to be taken into
consideration.
With this possibility in mind, we have reinvestigated
the reaction of 2 with diazomethane and now report on
a novel synthesis of 2, its reactions with diazomethane
and trimethylsilyldiazomethane, and the partial dis-
sociation of 2 into germylene molecules.
In fact, the reaction of 2 with diazomethane furnishes
a product in 80% yield for which the analytical and
spectral data suggest the existence of a 1:1 adduct of
the starting materials. An X-ray crystallographic analy-
sis (Figure 2), revealed that the methyleneamino-
(1) Compounds of Germanium, Tin, and Lead. 33. Part 32: Stu¨r-
mann, M.; Saak, W.; Weidenbruch, M.; Bernd, A.; Scheschkewitz, D.
Heteroatom Chem., in press.
(2) Reviews: (a) Tsumuraya, T.; Batcheller, S. A.; Masamune, S.
Angew. Chem. 1991, 103, 916; Angew. Chem., Int. Ed. Engl. 1991, 30,
902. (b) Driess, M.; Gru¨tzmacher, H. Angew. Chem. 1996, 108, 900;
Angew. Chem., Int. Ed. Engl. 1996, 35, 827. (c) Baines, K. M.; Stibbs,
W. G. In Multiply Bonded Main Group Metals and Metalloids; West,
R., Stone, F. G. A., Eds.; Academic Press: San Diego, 1996, p 275. (d)
Power, P. P. J . Chem. Soc., Dalton Trans 1998, 2939. (e) Weidenbruch,
M. Eur. J . Inorg. Chem. 1999, 373.
(5) Park, J .; Batcheller, S. A.; Masamune, S. J . Organomet. Chem.
1989, 367, 39.
(6) Ando, W.; Itoh, H.; Tsumuraya, T. Organometallics 1989, 8, 2759.
(7) Gynane, M. J . S.; Harris, D. H.; Lappert, M. F.; Power, P. P.;
Riv´ıe`re, P.; Riv´ıe`re-Baudet, M. J . Chem. Soc., Dalton Trans. 1977,
2004.
(8) Snow, J . T.; Murakami, S.; Masamune, S.; Williams, D. J .
Tetrahedron Lett. 1984, 25, 4191.
(9) Batcheller, S. A.; Tsumuraya, T.; Tempkin, O.; Davis, W. M.;
Masamune, S. J . Am. Chem. Soc. 1990, 112, 9394.
(3) (a) Ando, W.; Tsumuraya, T. Organometallics 1988, 7, 1882. (b)
Tsumuraya, T.; Sato, S.; Ando, W. Organometallics 1990, 9, 2061.
(4) Batcheller, S. A.; Masamune, S. Tetrahedron Lett. 1988, 29, 3383.
10.1021/om990337d CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/10/1999

3160 Organometallics, Vol. 18, No. 16, 1999
Scha¨fer et al.
Sch em e 1
F igu r e 1. Molecule of 2 in the crystal (hydrogen atoms
omitted). Ellipsoids are drawn at 50% probability. Selected
bond lengths (Å) and bond angles (deg): Ge(1)-Ge(2) 2.213-
(1), Ge(1)-C(1) 1.964(5), Ge(1)-C(16) 1.970(5), Ge(2)-C(31)
1.957(5), Ge(2)-C(46) 1.960(5), C(1)-Ge(1)-C(16) 111.5-
(2), C(31)-Ge(2)-C(46) 117.0(2).
F igu r e 2. Molecule of 7 in the crystal (hydrogen atoms
omitted). Ellipsoids are drawn at 50% probability. Selected
bond lengths (Å) and bond angles (deg): Ge(1)-Ge(2)
2.4237(4), Ge(1)-N(1) 1.883(2), Ge(2)-N(1) 1.924(2), N(1)-
N(2) 1.382(5), N(2)-C(1) 1.297(7), Ge(1)-C(2) 1.982(2), Ge-
(1)-C(17) 1.983(2), Ge(2)-C(32) 1.983(2), Ge(2)-C(47)
1.970(3), Ge(1)-Ge(2)-N(1) 49.72(6), N(1)-Ge(1)-Ge(2)
51.20(7), Ge(1)-N(1)-Ge(2) 79.08(8), N(1)-N(2)-C(1) 115.9-
(5), C(2)-Ge(1)-C(17) 111.04(9), C(32)-Ge(2)-C(47) 112.5-
(1).
Sch em e 2
with the normally considerably shortened Si/Si bond
lengths, was interpreted as an indication that these
compounds exist in a continuum ranging from the
classical three-membered ring structure to a π-interac-
tion between the Si/Si double bond and the hetero-
atom.10 However, a comparable bonding situation in 7
can probably be discounted since the Ge/Ge bond length
is only slightly shorter than the normal single-bond
length of 2.44 Å.
The reaction mode demonstrated here was previously
unknown in the chemistry of digermenes, although an
analogous ring system had been isolated from the
reaction of tetramesityldisilene with phenyldiazomethane,
albeit without a complete structural characterization.11
To determine whether the [2+1] addition process is
also realizable with substituted diazomethanes and if
the possibly formed compounds exhibit similar struc-
substituted azadigermirane 7 had been formed, pre-
sumably by a [2+1] cycloaddition without subsequent
loss of nitrogen. Interestingly, the digermirane 4 ob-
tained by Ando et al.3 in low yield could not be observed.
In the three-membered ring, the smaller angles are
found at the two germanium atoms and the larger angle
is found at the nitrogen atom. As expected, the substit-
uents at the nitrogen atom have a planar arrangement,
while, in contrast, the almost planar environments
(angular sum in each case 358.5°) of the two ipso-carbon
atoms and the respective other germanium atom about
the ring germanium atoms were not expected. A similar
situation was observed for disiliranes with an electrone-
gative atom in the three-membered ring; this, together
(10) Reviews: (a) Weidenbruch, M. Chem. Rev. 1995, 95, 1479. (b)
Okazaki, R.; West, R. In Multiply Bonded Main Group Metals and
Metalloids; West, R., Stone, F. G. A., Eds.; Academic Press: San Diego,
1996; p 231.
(11) Piana, H.; Schubert, U. J . Organomet. Chem. 1988, 348, C19.

Azadigermiridines
Organometallics, Vol. 18, No. 16, 1999 3161
Sch em e 3
F igu r e 3. Molecule of 8 in the crystal (hydrogen atoms
omitted). Ellipsoids are drawn at 50% probability. Selected
bond lengths (Å) and bond angles (deg): Ge(1)-Ge(2)
2.4415(5), Ge(1)-N(1) 1.866(3), Ge(2)-N(1) 1.914(3), N(1)-
N(2) 1.359(4), N(2)-C(61) 1.292(5), Ge(1)-C(1) 2.005(2),
Ge(1)-C(16) 2.015(2), Ge(2)-C(31) 2.004(2), Ge(2)-C(46)
2.010(2), Ge(1)-Ge(2)-N(1) 48.93(8), N(1)-Ge(1)-Ge(2)
50.62(9), Ge(1)-N(1)-Ge(2) 80.46(11), N(1)-N(2)-C(61)
120.6(3), C(1)-Ge(1)-C(16) 113.38(9), C(31)-Ge(2)-C(46)
107.66(9).
F igu r e 4. Molecule of 10 in the crystal (hydrogen atoms
omitted). Ellipsoids are drawn at 50% probability. Selected
bond lengths (Å) and angles (deg): Ge-O(1) 1.838(5), Ge-
O(2) 1.789(4), O(1)-C(6) 1.390(7), O(2)-C(1) 1.436(8),
O(2)-Ge-(O(1) 89.6(2), C(1)-O(2)-Ge 103.3(4), C(6)-
O(1)-Ge 111.6(4), C(15)-Ge-C(30) 114.1(2).
gested digermene using temperature-dependent electron
spectroscopy and determined a value of only 61.5 kJ
mol-1 for the dissociation into germylene molecules.12
Accordingly, we have performed some trapping reactions
in an attempt to detect an at least partial dissociation
of 2 to the germylene 6.
A solution of 2 in DME was heated in the presence of
the 1,2-quinone 9, a compound known for its ability both
to participate in [4+2] additions with double-bond
systems and to trap carbene analogues.13 This reaction
furnished colorless crystals of the 1,3-dioxa-2-germain-
dan 10 in 48% yield. The structure of 10 was confirmed
unequivocally by its analytical and spectral data as well
as by an X-ray crystallographic analysis (Figure 4). This
result indicates that, at least under these harsher
reaction conditions, digermene 2 at least partially
dissociates into two germylene molecules 6. However,
a trapping reaction of the digermene 2 by the 1,2-
quinone 9, followed by extrusion of a germylene mol-
ecule 6, cannot be completely excluded.
tural parameters, the digermene 2 was allowed to react
with trimethylsilyldiazomethane. Again we obtained
colorless crystals in a yield of 67%, the analytical,
spectral, and X-ray crystallographic data (Figure 3) of
which supported the existence of the [2+1] adduct 8.
Compound 8 crystallizes as two crystallographically
independent molecules with two of each occupying the
unit cell. The bond lengths and angles within the three-
membered ring of both molecules of 8 are not ap-
preciably different from those of compound 7. The ring
nitrogen atom in 8 also exists in a planar environment
with its substituents (angular sum 360°). However, the
coordination situations of the ipso-carbon atoms and the
respective other Ge atom differ at the two germanium
atoms. While the atom Ge(1) with an angular sum of
358.9° has an almost planar environment, the angular
sum of 346° at Ge(2) is indicative of a significant
pyramidalization. This is presumably due to the steric
influence of the trimethylsilyl group which forces the
aryl groups and hence the ipso-carbon atoms out of the
plane (Scheme 3).
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were carried out
in oven-dried glassware under an atmosphere of dry argon.
The cycloaddition processes described here support
the conclusions from previous investigations3 that the
digermene 2 also retains at least part of its structural
integrity in solution. Okazaki et al. recently studied the
bond dissociation energy of a similar, sterically con-
(12) Kishikawa, K.; Tokitoh, N.; Okazaki, R. Chem. Lett. 1998, 239.
(13) Weidenbruch, M.; Pellmann, A.; Pohl, S.; Saak, W.; Marsmann,
H. Chem. Ber. 1995, 128, 935.

3162 Organometallics, Vol. 18, No. 16, 1999
Ta ble 1. Cr ysta llogr a p h ic Da ta for 2, 7, 8, a n d 10
Scha¨fer et al.
2
7
8
10
empirical formula
fw
C
60H92Ge2
C61H94Ge2N2
1000.56
10.9205(10)
13.5314(11)
22.624(2)
77.60(1)
76.36(1)
68.380(9)
2989.9(5)
2
C64H102Ge2N2Si‚1/2DME
1117.80
21.705(1)
21.4197(9)
22.3357(14)
78.088(6)
75.347(7)
73.919(6)
6909.3(7)
4
C44H66GeO2
958.52
699.56
16.8443(10)
15.5059(13)
17.7051(12)
90
116.515(7)
90
4137.9(5)
4
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
13.0859(5)
13.5481(7)
18.2446(11)
98.302(7)
96.916(6)
111.948(5)
2914.6(3)
2
D(calcd) (g cm-3
cryst size (mm)
cryst syst
)
1.092
1.111
1.075
1.123
1.10 × 0.65 × 0.38
triclinic
213(2)
0.60 × 0.50 × 0.40
triclinic
213(2)
0.68 × 0.53 × 0.33
triclinic
193(2)
0.46 × 0.15 × 0.14
monoclinic
193(2)
temp (K)
space group
2θmax (deg)
no. of rflns measd
no. of unique rflns
lin abs coeff (mm-1
no. of params
P1h
P1h
P1h
P21/c
55
40031
7558
0.773
397
52
52
52
24031
10544
1.064
559
40173
10886
1.041
581
54502
25118
0.924
1186
)
R [I > 2σ(I)]
0.0767
0.1960
1.110
0.0346
0.0908
1.015
0.0480
0.1270
0.861
0.0804
0.1894
0.867
wR2 (all data)
GOF (F2)
The 1H and 13C{1H} NMR spectra were obtained on a Bruker
ARX 500 spectrometer using C6D6 as solvent. Elemental
analyses were performed by Analytische Laboratorien, D-51779
Lindlar, Germany.
of a 2 M solution of trimethylsilyldiazomethane (2 mmol) in
n-hexane (Fluka, D-82041 Deisenhofen, Germany) was added
dropwise to a mixture of 2 (0.50 g, 0.52 mmol) and copper
powder (40 mg) in DME (5 mL) with stirring. The resulting
mixture was allowed to warm to room temperature, and
stirring was continued for 36 h. The mixture was then filtered
through silica gel, and the filtrate was concentrated to a
volume of 2 mL and cooled to -18 °C to furnish 0.375 g (67%
yield) of colorless crystals of 8: mp 108 °C; 1H NMR δ 0.33 (s,
Tetr a k is(2,4,6-tr iisop r op ylp h en yl)d iger m en e (2). At 0
°C, a solution of 2,4,6-triisopropylphenyllithium14 (6.11 g, 29
mmol), prepared from 1-bromo-2,4,6-triisopropylbenzene15 and
n-butyllithium, in diethyl ether (50 mL) was added dropwise
to a solution of the germanium amide 5 (6.53 g, 16.6 mmol) in
diethyl ether (50 mL). The mixture was allowed to warm to
room temperature, and stirring was continued for 12 h. The
solvent was then removed and all volatile compounds were
distilled off at 170 °C/0.05 mbar. The residue was extracted
with n-hexane (120 mL) and the resulting solution concen-
trated to a volume of 30 mL. Cooling at -50 °C for 12 h
furnished 5.3 g (67% yield) of pale yellow crystals of 2: mp >
3
3
9 H, SiMe3), 0.55 (d, 6 H, J ) 6.6 Hz), 0.59 (d, 6 H, J ) 6.6
3
Hz), 0.76 (d, 6 H, 3J ) 6.6 Hz), 0.99 (d, 6 H, J ) 6.6 Hz), 1.10
3
3
(d, 12 H, J ) 6.6 Hz), 1.21 (d, 6 H, J ) 6.6 Hz), 1.22 (d, 6 H,
3J ) 6.6 Hz), 1.33 (d, 6 H, J ) 6.6 Hz), 1.45 (d, 6 H, J ) 6.6
3
3
Hz), 1.46 (d, 6 H, 3J ) 6.6 Hz), 1.51 (d, 6 H, J ) 6.6 Hz), 2.67
3
(sept, 2 H), 2.77 (sept, 2 H), 3.12 (s, DME), 3.32 (sept, 2 H,
overlapping with the DME signal), 3.33 (s, DME), 3.53 (sept,
2 H), 3.87 (m, 4 H), 6.99 (s, 4 H), 7.05 (s, 2 H), 7.20 (s, 2 H),
7.60 (s, 1 H, NdCH); 13C NMR δ -0.75, 23.59, 23.89, 23.95,
24.10, 24.23, 24.46, 24.86, 25.01, 25.49, 25.83, 32.99, 34.38,
34.65, 35.58, 36.57, 37.01, 58.88 (DME), 72.44 (DME), 121.51,
122.19, 122.74, 123.52, 145.58, 150.28, 150.40, 153.08, 153.38,
154.82. Anal. Calcd for C64H102Ge2N2Si‚1/2DME: C 70.90, H
9.65, N 2.50. Found: C 70.74, H 9.54, N 2.38.
1
280 °C; for H and UV/vis spectra, see ref 4; 13C NMR δ 24.28,
24.39, 24.47, 24.59, 25.03, 25.30, 34.81, 37.89, 38.07, 121.99,
122.99, 143.40, 150.25, 153.47, 153.73. Anal. Calcd for C60H92
Ge2: C 75.18, H 9.67. Found: C 75.00, H 9.51.
-
Me t h yle n e [2,2,3,3-t e t r a k is(t r iisop r op ylp h e n yl)a za -
d iger m ir id in -1-yl]a m in e (7). At -30 °C, a solution of
diazomethane (approximately 0.13 g, 0.3 mmol, prepared from
1.0 g (4.7 mmol) of p-tolylsulfonylmethylnitrosamide17) in
diethyl ether (18 mL) was added dropwise to a mixture of 2
(0.50 g, 0.52 mmol) and copper powder (40 mg) in DME (9 mL)
with stirring. The reaction mixture was allowed to warm to
room temperature, and stirring was continued for 36 h. The
mixture was then filtered through silica gel, and the filtrate
was concentrated to a volume of 2 mL and cooled to -18 °C to
afford 0.418 g (80% yield) of colorless crystals of 7: mp 148 °C
4,6-Di-ter t-bu tyl-2,2-bis(2,4,6-tr iisop r op ylp h en yl)-1,3-
d ioxa -2-ger m a in d a n (10). At room temperature, solid 9
(0.180 g, 8.2 mmol) was added to a solution of 2 (0.40 g, 0.42
mmol) in DME (5 mL) with stirring. The reaction mixture was
heated under reflux for 24 h and then the solvent distilled off.
The residue was extracted with n-hexane (15 mL), filtered
through silica gel, and concentrated to a volume of 3 mL.
Cooling at -18 °C afforded 0.28 g (48% yield) of colorless
crystals of 10: mp 102-106 °C; 1H NMR δ 1.12 (d, 12 H, 3J )
6.6 Hz), 1.18 (d, 12 H, 3J ) 6.6 Hz), 1.20 (d, 12 H, 3J ) 6.6
Hz), 1.32 (s, 9H), 1.59 (s, 9 H), 2.69 (sept, 2 H), 3.87 (sept, 4
H), 7.02 (s, 1 H), 7.09 (s, 4 H), 7.28 (s, 1 H); 13C NMR δ 23.41,
24.32, 24.55, 29.71, 31.51, 34.15, 34.60, 97.27, 109.60, 113.56,
121.78, 132.64, 134.20, 141.51, 150.28, 151.81, 153.46. Anal.
Calcd for C44H66GeO2: C 75.55, H 9.51. Found: C 75.31, H
9.56.
1
3
3
(dec); H NMR δ 0.55 (d, 6 H, J ) 6.6 Hz), 0.59 (d, 6 H, J )
3
3
6.6 Hz), 0.76 (d, 6 H, J ) 6.6 Hz), 0.99 (d, 6 H, J ) 6.6 Hz),
1.10 (d, 12 H, J ) 6.6 Hz), 1.21 (d, 6 H, J ) 6.6 Hz), 1.22 (d,
3
3
3
3
3
6 H, J ) 6.6 Hz), 1.33 (d, 6 H, J ) 6.6 Hz), 1.45 (d, 6 H, J
) 6.6 Hz), 1.46 (d, 6 H, 3J ) 6.6 Hz), 1.51 (d, 6 H, 3J ) 6.6
Hz), 2.67 (sept, 2 H), 2.77 (sept, 2 H), 3.32 (sept, 2 H), 3.53
(sept, 2 H), 3.87 (m, 4 H), 6.48 (m, 2 H, CH2), 6.99 (s, 4 H),
7.05 (s, 2 H), 7.20 (s, 2 H); 13C NMR δ 23.36, 23.63, 23.96,
24.04, 24.40, 24.94, 25.01, 25.47, 25.74, 33.02, 34.38, 34.63,
35.58, 36.31, 36.62, 37.13, 121.48, 122.09, 122.74, 123.44,
138.85, 140.05, 150.30, 153.04, 153.32, 154.12, 154.77. Anal.
Calcd for C61H94Ge2N2: C 73.22, H 9.47, N 2.80. Found: C
73.04, H 9.46, N 2.65.
(14) Bartlett, R. A.; Dias, H. V. R.; Power, P. P. J . Organomet. Chem.
1988, 341, 1.
(15) Whitesides, G. M.; Eisenhut, M.; Bu¨nting, W. M. J . Am. Chem.
Soc. 1974, 96, 5398.
(16) Sheldrick, G. M. SHELXL-97. Program for crystal structure
refinement; Universita¨t Go¨ttingen: Go¨ttingen. Germany, 1997.
(17) DeBoer, T. J .; Backer, H. J . Org. Synth. 1956, 36, 16.
[2,2,3,3-Tetr a kis(2,4,6-tr iisop r op ylph en yl)a za d iger m ir -
id in -1-yl]tr im eth ylsilylm eth ylen ea m in e (8). At 5 °C, 1 mL

Azadigermiridines
Organometallics, Vol. 18, No. 16, 1999 3163
Cr ysta llogr a p h ic An a lyses. Crystal and numerical data
of the structure determinations are given in Table 1. In each
case, the crystal was mounted in an inert oil. Data collection
was performed with a STOE IPDS area-detector using graphite-
monochromated Mo KR radiation (0.71073 Å). The structures
were solved by direct phase determinations and refined by full-
matrix least-squares techniques against F 2 with the SHELXL-
97 program system.16 Hydrogen atoms were placed in the
calculated positions, and all other atoms were refined aniso-
tropically. The NdCH2 group of 7 is disordered and was refined
on two positions with an occupancy factor of 0.5 each. The data
have been deposited with the Cambridge Crystallographic
Data Centre: CCDC-118 856 (2), CCDC-118 857 (7), CCDC-
118 859 (8), and CCDC-118 858 (10).
Ack n ow led gm en t. Financial support of our work
by the Deutsche Forschungsgemeinschaft and the Fonds
der Chemischen Industrie is gratefully acknowledged.
Su p p or t in g In for m a t ion Ava ila b le: Listing of atomic
coordinates, anisotropic displacement parameters, and bond
lengths and angles for 2, 7, 8, and 10. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM990337D