An eight-membered cyclic C,N-bis(germadiyl) bis(ketenimine)

Article abstract of DOI:10.1021/om971014p

The reaction of tert-butyllithium with (fluorodimesitylgermyl)- and (chlorodimesitylgermyl)-phenylacetonitrile (4a,b) leads to the lithium salts 5a (X = F) and 5b (X = Cl), which exhibit an ambident character: [>C^--C≡N?>C=C=N^-]Li

Full text of DOI:10.1021/om971014p

Organometallics 1998, 17, 1517-1522
1517
An Eigh t-Mem ber ed Cyclic C,N-Bis(ger m a d iyl)
Bis(k eten im in e)
Vladimir Ya. Lee,†,‡ Henri Ranaivonjatovo,† J ean Escudie´,*,† J acques Satge´,†
Antoine Dubourg,§ J ean-Paul Declercq,| Mikhail P. Egorov,‡ and
Oleg M. Nefedov‡
He´te´rochimie Fondamentale et Applique´e, UPRES A 5069, Universite´ Paul Sabatier,
31062 Toulouse Cedex 04, France, Groupe de Biochimie Structurale, URA 1111, Faculte´ de
Pharmacie, 15 Avenue Charles Flahault, 34060 Montpellier, France, Laboratoire de Chimie
Physique et de Cristallographie, Universite´ Catholique de Louvain, Place Pasteur 1,
B-1348 Louvain-La-Neuve, Belgium, and N. D. Zelinsky Institute of Organic Chemistry,
Leninsky Prospect 47, Moscow B-334, Russia
Received November 17, 1997
The reaction of tert-butyllithium with (fluorodimesitylgermyl)- and (chlorodimesitylgermyl)-
phenylacetonitrile (4a ,b) leads to the lithium salts 5a (X ) F) and 5b (X ) Cl), which exhibit
an ambident character: [>C--CtNT>CdCdN-]Li+. Quenching of 5a with triphenylbro-
momethane affords the germylketenimine 8, Mes2FGeC(Ph)dCdNCPh3. 1H dynamic NMR
spectroscopy allows the determination of the activation energy of the nitrogen inversion
∆G* ) 9.9 ( 0.2 kcal/mol. In the absence of a trapping reagent, 5 undergoes an elimination
of lithium halide with formation of the eight-membered cyclic C,N-bis(germadiyl) bis-
(ketenimine) 1, which is the first ring containing two ketenimine moieties. 1 has been
characterized by IR (ν(CdCdN) 2015 cm-1) and 13C NMR spectroscopy (170.87 ppm for the
sp carbon) and by an X-ray structure determination, which displays a “cyclohexane” type
structure in a chair conformation.
Ch a r t 1
In tr od u ction
Ketenimines have attracted considerable attention
because they are versatile synthetic reagents.1 When
substituted at nitrogen by heavy elements of Group 14
they may be useful synthons, due to the high reactivity
both of the ketenimine moiety and of the Group 14
metal-nitrogen bond. Some silylketenimines2 of type A,
B or C and stannylketenimines3 of type C have been
reported, but no germylketenimines have been charac-
terized or isolated thus far (Chart 1).
compounds, since it contains two germanium-keten-
imine moieties in a ring.
Resu lts a n d Discu ssion
The synthesis of 1 is based on the previous prepara-
tion of (fluorodimesitylgermyl)- and (chlorodimesitylger-
myl)phenylacetonitrile (4a,b) by reaction of R-lithiophen-
ylacetonitrile (2) in THF with the dihalodimesityl-
germane 3 at -78 °C. 4a can be converted quantita-
tively to 4b upon refluxing in concentrated HCl. The
products 4 were characterized by their spectroscopic
data. As expected, in their 1H and 13C NMR spectra
the two mesityl groups were nonequivalent and the IR
spectra showed the characteristic CtN vibrations at
2229 (4a ) and 2215 (4b) cm-1 (Scheme 1).
Addition of t-BuLi to colorless solutions of 4 in Et2O
at -78 °C gave immediately deep yellow solutions which
slowly lost their color with the formation of a precipitate
of the lithio compounds 5. When suspensions of 5 were
warmed to room temperature, a lemon yellow compound
precipitated after stirring overnight at 20 °C. After its
purification by crystallization, spectroscopic studies
showed it to be the bis(ketenimine) 1 (Scheme 2).
In 1H NMR spectrum of 1 the four mesityl groups
appear equivalent. Of course, the molecule has a center
of symmetry and is not chiral, but the two mesityl
We report here the synthesis of two germanium-
containing ketenimines, one of type A (8) and the other
of type C (1). The latter represents a new class of
† Universite´ Paul Sabatier.
‡ N. D. Zelinsky Institute of Organic Chemistry.
§ URA 1111, Faculte´ de Pharmacie.
| Universite´ Catholique de Louvain.
(1) (a) Michael, J . P.; De Koning, C. B. In Comprehensive Organic
Functional Group Transformations; Katritzky, A. R., Meth-Cohn, O.,
Rees, C. W., Eds.; Elsevier: New York, 1995; Vol. 3, Chapter 3.17, p
555. (b) Aumann, R. Angew. Chem., Int. Ed. Engl. 1988, 27, 1456. (c)
Gambaryan, N. P. Russ. Chem. Rev. (Engl. Transl.) 1976, 45, 630. (d)
Krow, G. R. Angew. Chem., Int. Ed. Engl. 1971, 10, 435.
(2) (a) Matsuda, I.; Okada, H.; Izumi, Y. Bull. Chem. Soc. J pn. 1983,
56, 528. (b) Okada, H.; Matsuda, I.; Izumi, Y. Chem. Lett. 1983, 97. (c)
Gabriel, A. O.; Riedel, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 384.
(d) Prober, M. J . Am. Chem. Soc. 1956, 78, 2274. (e) Gillette, G. R.;
Baceiredo, A.; Bertrand, G. Angew. Chem., Int. Ed. Engl. 1990, 29,
1429. (f) Differding, E.; Vandevelde, O.; Roekens, B.; Van, T. T.; Ghosez,
L. Tetrahedron Lett. 1987, 28, 397. (g) Yamakado, Y.; Ishiguro, M.;
Ikeda, N.; Yamamoto, H. J . Am. Chem. Soc. 1981, 103, 5568. (h)
Seyferth, D.; Langer, P.; Do¨ring, M. Organometallics 1995, 14, 4457.
(i) Sato, Y.; Niinomi, Y. J . Chem. Soc., Chem. Commun. 1982, 56. (j)
Gillette, G. R.; Igau, A.; Baceiredo, A.; Bertrand, G. New J . Chem. 1991,
15, 393.
(3) Miller, E.; Sommer, R.; Neumann, W. P. Liebigs Ann. Chem.
1968, 718, 1.
S0276-7333(97)01014-5 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 03/14/1998

1518 Organometallics, Vol. 17, No. 8, 1998
Lee et al.
Sch em e 1
Sch em e 3
Sch em e 2
Elimination of lithium halide from ((halogermyl)-
fluorenyl)lithium derivatives 6 generally occurs at low
temperature to afford the corresponding germenes 78-10
(Scheme 3). In contrast, in the case of 5, such elimina-
tion of LiX, leading to germaacrylonitrile Mes2GedC-
(Ph)CN, has never been observed.
The ambident character of intermediate Li salt 5a
was confirmed by trapping reactions with electrophiles.
Thus, quenching of 5a with Ph3CBr at 20 °C quantita-
tively gives the germylketenimine 8 (Scheme 4). In
contrast, when 5a was quenched with Me2SO4 or MeI,
only the C-alkylation product 9 was isolated in good
yield. This result could be explained by steric control
of the reaction, which leads to N-alkylation in the case
of the bulky Ph3C group and to C-alkylation with the
less sterically hindered methyl group.
However, we cannot completely exclude an alternative
possibility for the formation of 9: previous N-alkylation
of 5a leading to the intermediate 10 followed by a
ketenimine-nitrile rearrangement. Examples of such
conversion have been previously reported.11
The presence of the ketenimine moiety in 8 was
evidenced by a strong band at 2011 cm-1 in the IR
spectrum1 and by a low-field signal at 173.89 ppm in
the 13C NMR spectrum, which is characteristic for the
sp carbon.1,4
groups on each germanium atom should be different.
Since 1 has a “cyclohexane” type structure (see the X-ray
structure determination), they are in “axial” and “equa-
torial” positions. However, attempts to differentiate
them were unsuccessful, even at -100 °C. Such a result
is not surprising, since the rapid axial-equatorial
equilibrium generally occurs at even very low temper-
ature. Also, the steric strain in 1 probably is not very
high. The 13C NMR spectrum shows a signal at 170.87
ppm, characteristic of the sp carbon of the CdCdN
moiety.1,4 The ketenimine structure was also evidenced
in the IR spectrum by a strong band at 2015 cm-1.1 1 is
the first germanium-containing ketenimine and also the
first compound with two ketenimine moieties in the
same heterocycle. It is unexpectedly stable compared
with the only known eight-membered cyclic keten-
imine,5 which was obtained as an unstable oil.
Due to the chiral >CdCdN- moiety in 8, the two
1
mesityl groups are diastereotopic. However, in the H
NMR spectrum the two mesityl groups appeared equiva-
lent, because of the rapid inversion of nitrogen. Low-
temperature 1H dynamic NMR spectra allowed the
determination of the coalescence temperature of the
o-Me groups of the mesityl groups (-55 °C) and of the
activation energy of the nitrogen inversion (∆G* ) 9.9
( 0.2 kcal/mol). Such a value corresponds to the
previously reported data for other N-substituted keten-
imines.12,13 Owing to the large steric hindrance caused
1 is poorly soluble in the usual organic solvents. It
can be handled in air for some minutes without decom-
position. The Ge-N bond, which generally is very
reactive6 and is easily cleaved by water, is relatively
stable in this case, probably due to the steric protection
caused by the bulky mesityl groups.7 However, yellow
solutions of 1 in commercial grade benzene or diethyl
ether become colorless after 2 days because of decom-
position.
(8) Couret, C.; Escudie´, J .; Satge´, J .; Lazraq, M. J . Am. Chem. Soc.
1987, 109, 4411.
(9) Lazraq, M.; Couret, C.; Escudie´, J .; Satge´, J .; Soufiaoui, M.
Polyhedron 1991, 10, 1153.
(10) Anselme, G.; Escudie´, J .; Couret, C.; Satge´, J . J . Organomet.
Chem. 1991, 403, 93.
(11) (a) A facile 1,3-rearrangement of the ketenimine Ph2CdCd
NCHMePh to the nitrile Ph2C(CHMePh)CtN has been reported by:
Singer, L. A.; Lee, K. W. J . Chem. Soc., Chem. Commun. 1974, 962.
Lee, K. W.; Horowitz, N.; Ware, J .; Singer, L. A. J . Am. Chem. Soc.
1977, 99, 2622. (b) A similar rearrangement from the ketenimine Me3-
SiCHdCdNSiMe3 to the nitrile (Me3Si)2CH-CtN at room tempera-
ture has also been observed by Prober.2d
(12) (a) J ochims, J . C.; Herzberger, S.; Gambke, B.; Anet, F. A. L.
Tetrahedron Lett. 1977, 26, 2255. (b) J ochims, J . C.; Lambrecht, J .;
Burkert, U.; Zsolnai, L.; Huttner, G. Tetrahedron 1984, 40, 893. (c)
Eberl, K.; Roberts, J . D. Org. Magn. Reson. 1981, 17, 180. (d) J ochims,
J . C.; Anet, F. A. L. J . Am. Chem. Soc. 1970, 92, 5524.
(13) There is a large difference in ∆G* values between 1 and an
eight-membered cyclic ketenimine,5 for which the nitrogen inversion
of the CdCdN moiety requires 19.0 kcal/mol due to the steric strain.
(4) Firl, J .; Runge, W.; Hartmann, W.; Utikal, H. P. Chem. Lett.
1975, 51.
(5) Firl, J .; Schink, K.; Kosbahn, W. Chem. Lett. 1981, 527.
(6) Rivie`re, P.; Rivie`re-Baudet, M.; Satge´, J . In Comprehensive
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson,
G., Eds.; Pergamon Press: New York, 1995; Vol. 2, Chapter 5, p 139.
(7) For example, Mes3GeNH2 is very stable toward moisture due to
the steric protection of the Ge-N bond: Rivie`re-Baudet, M.; Morere,
A.; Britten, J . F.; Onyszchuk, M. J . Organomet. Chem. 1992, 423, C5.

A Cyclic C,N-Bis(germadiyl) Bis(ketenimine)
Organometallics, Vol. 17, No. 8, 1998 1519
Sch em e 4
Sch em e 5
Ta ble 1. Cr ysta llogr a p h ic Da ta , Exp er im en ta l
Con d ition s, a n d Su m m a r y of Str u ctu r a l
Refin em en t for 1a
by the bulky CPh3 group, 8 is quite stable. It can be
isolated in pure form.
8 is rather stable toward hydrolysis but slowly
decomposes in benzene or chloroform solutions at room-
temperature, reverting to the starting material 4a and
giving also some unidentified products. We suggest that
the decomposition of 8 involves homolytic cleavage of
the N-CPh3 bond. This is supported by the work of
Hegarty et al.,14 who observed a facile thermal cleavage
of the N-CHPh2 bond in ketenimines via a radical
mechanism. Thus, for ambident radical 11, there are
two possible processes: (a) H abstraction by the nitrogen
atom followed by a rearrangement of the transient
ketenimine 12 with final formation of 4a and (b) H
abstraction by the carbon atom leading directly to 4a
(Scheme 5).
X-r a y Str u ctu r e Deter m in a tion . The structure of
1 was unambiguously proved by an X-ray study (see
Tables 1-3 and Figure 1). The molecule is centrosym-
metric. The sum of angles at C(2) is very close to 360°
(359.3°), showing an almost complete planarity around
the C(1)-C(2) double bond. The C(2)C(1)N arrange-
ment is not completely linear but rather is bent to 171.8-
(5)°. It is in the normal range, since the CdCdN unit
generally deviates from linearity by 5-10°.12b,15 A more
distorted CdCdN bond angle (163.8°) was even ob-
served in a seven-membered-ring ketenimine.16 Since
the molecule is centrosymmetric, the four atoms NC-
empirical formula
mw
C52H54Ge2N2
852.15
cryst size (mm)
cryst syst
space group
cell dimens
a (Å)
0.5 × 0.5 × 0.2
monoclinic
P21/n
11.969(2)
b (Å)
10.758(2)
c (Å)
17.269(3)
â (deg)
96.27(1)
2210.3(7)
1.28
V (Å3)
Dcalcd (g cm-3
)
Z
2
Mo KR radiation
F(000)
λ ) 0.710 69 Å
888
T (K)
293
2θmax (deg)
55
5064
2875
no. of rflns collected
no. of obsd rflns with I > 2σ(I)
range of hkl
0 < h < 15, 0 < k < 13,
-22 < l < 22
refined ls R1 factor obsd (F > 4σ(F))
refined ls wR2 factor obsd (I > 2σ(I))
s
0.06
0.15
0.95
-0.60 to +0.91
residual density, e Å-3
W ) 1/[σ2(Fo2) + (0.124P)2 + 0.384P], with P ) [Fo + 2Fc2]/3.
a
2
(1)NaC(1a) are exactly in the same plane. C(2) and C(2a)
are very close to this plane ((0.172(8) Å): this means
that the six atoms NC(1)C(2)NaC(1a)C(2a) are approxi-
mately in the same plane. One of the germanium atoms
is above and the other one below the mean plane NC-
(1)C(2)NaC(1a)C(2a) at a distance of 0.93(1) Å. Due to
the centrosymmetry of 1, the GeC(2) and GeaC(2a)
(14) Clarke, L. F.; Hegarty, A. F.; O’Neill, P. J . Org. Chem. 1992,
57, 362.
(15) Dely, J . J . J . Org. Chem. 1961, 26, 2801.
(16) Huisgen, R.; Langhals, E.; No¨th, H. J . Org. Chem. 1990, 55,
1472.

1520 Organometallics, Vol. 17, No. 8, 1998
Lee et al.
F igu r e 1. PLATON19 view of 1 (ellipsoids are drawn at the 50% probability level).
Ta ble 2. Selected Bon d Len gth s (Å) a n d
An gles (d eg)
Ch a r t 2
Ge-N
1.926(4)
1.939(5)
1.945(5)
1. 941(5)
C(1)-N
C(1)-C(2)
C(2)-C(3)
1.215(6)
1.312(7)
1.469(7)
Gea-C(2)
Ge-C(18)
Ge-C(9)
N-Ge-C(2a)
98.2(2)
99.4(2)
120.5(2)
108.0(2)
110.6(2)
116.8(2)
N-C(1)-C(2)
C(1)-N-Ge
C(1)-C(2)-C(3)
C(1)-C(2)-Gea
C(3)-C(2)-Gea
171.8(5)
123.5(3)
121.9(4)
110.4(4)
127.0 (4)
N-Ge-C(18)
C(2a)-Ge-C(18)
N-Ge-C(9)
points were determined on a Wild Leitz-Biomed apparatus.
Mass spectra were obtained on a Hewlett-Packard 5989A
spectrometer by EI at 70 eV. IR spectra were recorded on a
Perkin-Elmer 1600 FT-IR spectrometer. The UV spectrum
was recorded on a Hewlett-Packard 8453 UV-vis spectrom-
eter. Elemental analyses were performed by the “Service de
Microanalyse de l’Ecole de Chimie de Toulouse”.
C(2a)-Ge-C(9)
C(18)-Ge-C(9)
Ta ble 3. Selected Tor sion An gles (d eg)
C(9)-Ge-N-C(1)
C(2)-C(1)-N-Ge
C(2a)-Ge-N-C(1)
N-Ge-C(2a)-C(1a)
N-Ge-C(2a)-C(3a)
-178.2(4)
-109.3(3)
67.0(4)
-46.9(4)
123.8(4)
Mes2GeCl2 was synthesized according to the literature17
18
from MesBr, Mg and GeCl4. Mes2GeF2 was prepared from
Mes2GeCl2 by treatment with MeOH/NEt3 and then with HF/
H2O.
bonds, as well as the GeN and GeaNa bonds, are parallel.
From these data, it appears that 1 has a “cyclohexane”
type structure in a “chair” conformation (Chart 2 and
Figure 1).
The study of the reactivity of 1, which seems accord-
ing to our first experiments a good precursor of high-
molecular-weight polymers, is now in progress.
Syn t h esis of (F lu or od im esit ylger m yl)p h en yla cet o-
n itr ile (4a ). A solution of n-BuLi (9.5 mL, 1.6 M in hexane,
16.2 mmol) was added to a solution of phenylacetonitrile (1.72
g, 14.7 mmol) in THF (20 mL) at -78 °C. After 20 min the
reaction mixture was transferred via cannula to a solution of
Mes2GeF2 (5 g, 14.3 mmol) in THF (40 mL) stored at -78 °C.
Stirring was continued at -78 °C for 40 min. Then the
reaction mixture was warmed to room temperature and was
stirred for 1 h. Solvents were removed in vacuo, the residue
was dissolved in Et2O, LiF was filtered out, and the filtrate
was evaporated in vacuo. The residue was recrystallized from
pentane, yielding 4.40 g (69%) of 4a as white crystals (mp
149.0-149.5 °C).
Exp er im en ta l Section
All experiments were carried out in flame-dried glassware
under a nitrogen atmosphere using high-vacuum-line tech-
niques. Solvents were dried and freshly distilled from sodium
benzophenone ketyl and carefully deoxygenated on the vacuum
line by several “freeze-pump-thaw” cycles. NMR spectra
were recorded in CDCl3 on the following spectrometers: 1H,
Bruker AC80 (80.13 MHz) and Bruker AC200 (200.13 MHz);
13C{1H}, Bruker AC200 (50.32 MHz) (reference TMS); 19F,
Bruker AC80 (75.39 MHz) (reference CF3COOH). Melting
(17) Rivie`re, P.; Rivie`re-Baudet, M. In Organometallic Syntheses;
King, R. B., Eisch, J . J ., Eds.; Elsevier: New York, 1988; Vol. 4, p 542.
(18) Rivie`re, P.; Rivie`re-Baudet, M.; Castel, A.; Desor, D.; Abden-
nadher, C.; Satge´, J . Phosphorus, Sulfur Silicon Relat. Elem. 1991,
61, 189.
(19) Spek, A. L. Acta Crystallogr. 1990, A46, C34.

A Cyclic C,N-Bis(germadiyl) Bis(ketenimine)
Organometallics, Vol. 17, No. 8, 1998 1521
5
1H NMR: δ 2.17 (d, J H-F ) 1.9 Hz, 6H, o-Me), 2.27 (s, 6H,
°C. The lithium derivative 5a was prepared by reaction of
0.7 mL of a 1.7 M solution of t-BuLi in pentane (1.19 mmol)
and 4a (0.5 g, 1.12 mmol) in Et2O (15 mL) at -78 °C. The
color became bright yellow immediately. After 5 min MeI (0.23
g, 1.60 mmol) was added to the yellow solution at -78 °C. The
reaction mixture was stirred for 30 min, was then warmed to
room temperature, and was stirred for 1 h. Inorganic salts
were filtered out, and the filtrate was concentrated in vacuo,
giving 0.29 g (57%) of 9 as white crystals (mp 174-176 °C).
5
3
p-Me), 2.28 (d, J H-F ) 1.9 Hz, 6H, o-Me), 4.14 (d, J H-F ) 4.8
Hz, 1H, CH), 6.81 (s, 4H, H arom Mes), 7.11-7.26 (m, 5H, H
arom Ph).
13C NMR: δ 21.18 (p-Me), 22.98 and 23.04 (o-Me), 32.49 (d,
2J C-F ) 14.2 Hz, C-H), 119.80 (d, 3J C-F ) 3.0 Hz, CtN), 127.34
(p-C Ph), 128.37 and 128.55 (o- and m-C Ph), 129.48 (m-C Mes),
2
130.50 (d, J C-F ) 9.3 Hz, ipso-C Mes), 131.15 (ipso-C Ph),
2
131.53 (d, J C-F ) 10.5 Hz, ipso-C Mes), 140.85 and 140.88
5
(p-C Mes), 142.74 and 143.09 (o-C Mes).
1H NMR: δ 2.06 (d, J H-F ) 1.8 Hz, 6H, o-Me), 2.07 (s, 3H,
5
19F NMR: δ -105.19 (s).
Me), 2.22 (s, 3H, p-Me), 2.29 (s, 3H, p-Me), 2.44 (d, J H-F
)
MS (EI, 70 eV, 74Ge): m/z 447 (M, 5), 428 (M - F, 10), 331
(Mes2GeF, 100), 311 (Mes2Ge - 1, 22).
1.7 Hz, 6H, o-Me), 6.72 (s, 2H, H arom Mes) and 6.87 (s, 2H,
H arom Mes), 7.20-7.48 (m, 5H, H arom Ph).
13C NMR: δ 21.09 (p-Me), 23.08 and 23.16 (o-Me), 23.89 (d,
IR (KBr, cm-1): ν(CtN) 2229 (w).
2
3J C-F ) 4.2 Hz, Me), 37.95 (d, J C-F ) 14.3 Hz, C-Me), 123.67
Anal. Calcd for C26H28FGeN: C, 69.80; H, 6.26; N, 3.13.
Found: C, 69.63; H, 6.19; N, 3.06.
3
(d, J C-F ) 3.3 Hz, CtN), 127.46 (p-C Ph), 128.39 and 128.68
(o- and m-C Ph), 129.33 and 129.80 (m-C Mes), 131.80 (d, 2J C-F
) 9.3 Hz, ipso-C Mes), 132.05 (d, 2J C-F ) 9.9 Hz, ipso-C Mes),
137.64 (ipso-C Ph), 140.57 and 140.63 (p-C Mes), 143.25 (o-C
Mes).
Syn t h esis of (Ch lor od im esit ylger m yl)p h en yla cet o-
n itr ile (4b). A solution of n-BuLi (10.0 mL, 1.6 M in hexane,
16 mmol) was added dropwise to a solution of phenylacetoni-
trile (1.8 g, 15.38 mmol) in THF (20 mL) with stirring at -78
°C. The solution became bright yellow. After 15 min the
reaction mixture was transferred via cannula to a solution of
Mes2GeCl2 (5.64 g, 14.72 mmol) in THF (50 mL) stored at -78
°C. After the addition the reaction mixture was stirred at -78
°C for 30 min and then was warmed to room temperature with
stirring for 1 h. The solvents were removed in vacuo, the
residue was dissolved in Et2O, LiCl was filtered out, and the
filtrate was evaporated in vacuo. The crude product was
recrystallized from i-PrOH to give 4.38 g (65%) of white
crystals of 4b (mp 138-140 °C).
19F NMR: δ -103.86 (s).
MS (EI, 70 eV, 74Ge): m/z 461 (M, 8), 442 (M - F, 2), 331
(Mes2GeF, 100), 311 (Mes2Ge - 1, 18).
IR (KBr, cm-1): ν(CtN) 2223 (w).
Anal. Calcd for C27H30FGeN: C, 70.28; H, 6.51; N, 3.04.
Found: C, 70.03; H, 6.44; N, 3.18.
b. F r om 5a a n d Dim eth yl Su lfa te a t Room Tem p er a -
tu r e. The lithium derivative 5a was prepared at -78 °C as
previously described. After 10 min the cooling bath was
removed and the mixture was warmed to room temperature.
At 20 °C the yellow color disappeared almost completely and
a white solid precipitated. Me2SO4 (0.34 g, 2.7 mmol) was
added at room temperature, and the reaction mixture was
stirred for 1 h. Inorganic salts were filtered out, and the
filtrate was concentrated in vacuo, giving 0.35 g (69%) of 9.
Syn t h esis of N-(t r ip h en ylm et h yl)(flu or od im esit yl-
ger m yl)p h en ylk eten im in e (8). The lithium derivative 5a
was prepared at -78 °C as previously described. After 10 min
of stirring at -78 °C the cooling bath was removed and the
mixture was warmed to room temperature. A white solid
precipitated from the reaction mixture. Ph3CBr (0.36 g, 1.12
mmol) was added at room temperature to the white solid,
which disappeared in a few minutes. The yellow solution was
stirred for 1 h at room temperature. LiBr was filtered out,
and the filtrate was evaporated in vacuo. 8 formed in
1H NMR: δ 2.18 (s, 6H, o-Me), 2.25 (s, 12H, o- and p-Me),
4.16 (s, 1H, CH), 6.77 (s, 4H, H arom Mes), 7.01-7.21 (m, 5H,
H arom Ph).
13C NMR: δ 21.06 (p-Me), 23.47 and 23.87 (o-Me), 34.92 (C-
H), 120.50 (CtN), 127.42 (p-C Ph), 128.17 and 128.81 (m-C
Ph and o-C Ph), 129.87 (m-C Mes), 131.24 (ipso-C Ph), 132.34
and 133.78 (ipso-C Mes), 140.38 and 140.45 (p-C Mes), 141.84
and 142.58 (o-C Mes).
MS (EI, 70 eV, 74Ge): m/z 463 (M, 4), 428 (M - Cl, 4), 347
(Mes2GeCl, 100), 311 (Mes2Ge - 1, 20).
IR (KBr, cm-1): ν(CtN) 2215 (w).
Anal. Calcd for C26H28ClGeN: C, 67.39; H, 6.05; N, 3.02.
Found: C, 67.21; H, 6.16; N, 2.81.
Syn t h esis of 3,7-Dip h en yl-2,2,6,6-t et r a k is(2,4,6-t r i-
m eth ylph en yl)-2,6-diger m a-1,5-diazacyclooctatetr a-3,4,7,8-
en e (1). A 1.4 mL amount of a 1.7 M solution of t-BuLi in
pentane (2.38 mmol) was added to a solution of 4a (0.99 g,
2.21 mmol) in Et2O (30 mL) at -78 °C. The color immediately
became bright yellow. After 10 min the cooling bath was
removed and the reaction mixture was warmed to room
temperature. The yellow color disappeared, and the white
solid 5a precipitated. After the mixture was stirred overnight,
this white solid was converted to 1 in the form of a yellow solid.
This yellow solid was filtered and dried in vacuo, yielding 0.90
g (95%) of 1, which was recrystallized from benzene-hexane
(30/70) to give lemon yellow crystals, mp 211-213 °C dec.
1H NMR: δ 2.27 (s, 12H, p-Me), 2.35 (s, 24H, o-Me), 6.83
(s, 8H, H arom Mes), 6.58-6.99 (m, 10H, H arom Ph).
13C NMR: δ 21.15 (p-C Me), 23.57 (o-C Me), 51.33
(C(Ph)dCdN), 122.37 (p-C Ph), 125.32 (m-C Ph), 128.46 (o-C
Ph), 129.54 (m-C Mes), 134.08 (ipso-C Ph), 137.72 (ipso-C Mes),
139.74 (p-C Mes), 143.50 (o-C Mes), 170.87 (C(Ph)dCdN).
IR (KBr, cm-1): ν(CdCdN) 2015 (vs).
1
quantitative yield (according to H NMR data). Recrystalli-
zation from pentane gave pale yellow crystals (mp 101-103
°C dec).
5
1H NMR: δ 2.16 (d, J H-F ) 1.7 Hz, 12H, o-Me), 2.24 (s,
6H, p-Me), 6.74 (s, 4H, H arom Mes), 6.67-7.30 (m, 20H, H
arom Ph). At -70 °C the two Mes groups appeared to be
nonequivalent with the following chemical shifts for the methyl
groups: o-Me, 1.97 and 2.62 ppm (two broad s), p-Me, 2.31
ppm (s).
13C NMR: δ 21.25 (p-Me), 22.81 and 22.88 (o-Me), 64.71 (d,
2J C-F ) 17.9 Hz, CdCdN), 77.73 (CPh3), 124.85-130.15 (o-,
2
m-, p-C Ph and m-C Mes), 132.12 (d, J C-F ) 11.9 Hz, ipso-C
Mes), 135.39 (ipso-C Ph), 139.97 (p-C Mes), 143.75 and 144.33
(o-C Mes and ipso-C CPh3), 173.89 (CdCdN).
19F NMR: δ -97.19 (s).
MS (EI, 70 eV, 74Ge): m/z 446 (Mes2Ge(F)-C(Ph)dCdN, 2),
331 (Mes2GeF, 13), 243 (Ph3C, 83), 165 (Ph3C-Ph - 1, 78), 77
(Ph, 100).
UV (λmax in cyclohexane): 202 (ꢀ ) 3859), 286 (ꢀ ) 579),
IR (KBr, cm-1): ν(CdCdN) 2011 (vs).
369 (ꢀ ) 8) nm.
Anal. Calcd for C45H42FGeN: C, 78.37; H, 6.09; N, 2.03.
Anal. Calcd for C52H54Ge2N2: C, 73.29; H, 6.39; N, 3.29.
Found: C, 73.24; H, 6.50; N, 3.16.
1 was also obtained in nearly quantitative yield from 4b
using the same procedure.
Syn th esis of (F lu or od im esitylger m yl)m eth ylp h en yl-
a ceton itr ile (9). a . F r om 5a a n d Meth yl Iod id e a t -78
Found: C, 78.52; H, 6.04; N, 2.10.
X-r a y Cr ysta llogr a p h ic An a lysis of 1. Yellow crystals
of 1, suitable for X-ray analysis, were obtained by slow
evaporation of a saturated benzene-hexane (30/70) solution
of 1 at room temperature. The data were collected on a Huber
diffractometer with graphite-monochromated Mo KR radiation

1522 Organometallics, Vol. 17, No. 8, 1998
Lee et al.
(λ ) 0.710 69 Å). Final unit cell parameters for 1 were
obtained by least-squares analysis of setting angles for 30
reflections; 14 < 2θ < 30°. The intensities of the standard
reflection (0,-4,4) were measured every 50 reflections during
the data collection, showing no significant variation. All cal-
culations were performed with the programs SHELXS-86 and
SHELXL-93 using F2. Hydrogen atoms were placed in calcu-
lated positions, and all other atoms were refined with aniso-
tropic thermal parameters. Residual densities close to ger-
manium (d < 0.944 Å) are rather important. The other
residual densities are in the normal range (-0.41 to 0.46 e
Å-3).
Ack n ow led gm en t. V.Y.L. thanks the “Ministe`re de
l’Education Nationale, de la Recherche et de la Tech-
nologie” for a postdoctoral grant.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates, anisotropic temperature factors, bond lengths,
bond angles, and torsion angles and additional PLUTO and
crystal-packing diagrams (12 pages). Ordering information is
given on any current masthead page.
OM971014P