COMMUNICATIONS
carbenes.[13] Moreover, kinetic studies have shown that the
reactivity of alcohols towards carbenes is proportional to their
acidity and that the relative reactivity of tertiary alcohols such
as tBuOH is low.[14] As diazogermylene 2 does not react with
tBuOH at room temperature or with MeOH at low temper-
ature, it does not behave as a germylene, and this rules out
mechanism 2. The lack of typical carbene and germylene
reactivity of I suggests that it is reasonable to postulate
mechanism 3, in which the germyne is trapped by two
equivalents of alcohol.
In conclusion, diazogermylenes, in which a carbenoid
species is adjacent to a Group 14 atom bearing both a lone
pair and vacant orbitals, are promising precursors to germa-
nium ± carbon triple bonds. Our results, which constitute the
first chemical evidence for a germyne, contrast with ab initio
quantum mechanical calculations of Stogner and Grev on the
[1] R. West, M. J. Fink, J. Michl, Science 1981, 214, 1343 ± 1344.
Â
[2] a) P. P. Power, Chem. Rev. 1999, 99, 3463 ± 3503; b) J. Escudie, C.
Couret, H. Ranaivonjatovo, Coord. Chem. Rev. 1998, 178 ± 180, 565 ±
592.
[3] L. Pu, B. Twamley, P. P. Power, J. Am. Chem. Soc. 2000, 122, 3524 ±
3525.
[4] M. Karni, Y. Apeloig, D. Schröder, W. Zummack, R. Rabezzana, H.
Schwarz, Angew. Chem. 1999, 111, 344 ± 347; Angew. Chem. Int. Ed.
1999, 38, 331 ± 335, and references therein.
Á
Á
[5] S. Foucat, T. Pigot, G. Pfister-Guillouzo, H. Lavayssiere, S. Mazieres,
Organometallics 1999, 18, 5322 ± 5329.
[6] a) R. S. Simons, P. P. Power, J. Am. Chem. Soc. 1996, 118, 11966 ±
11967; b) L. Pu, B. Twamley, S. T. Haubrich, M. M. Olmstead, B. V.
Mork, R. S. Simons, P. P. Power, J. Am. Chem. Soc. 2000, 122, 650 ±
656.
[7] a) H. Meyer, G. Baum, W. Massa, A. Berndt, Angew. Chem. 1987, 99,
790; Angew. Chem. Int. Ed. Engl. 1987, 26, 798 ± 799; b) A. Berndt, H.
Meyer, G. Baum, W. Massa, S. Berger, Pure Appl. Chem. 1987, 59,
1011 ± 1014; c) M. Weidenbruch, H. Kilian, M. Stürmann, S. Pohl, W.
Saak, H. Marsmann, D. Steiner, A. Berndt, J. Organomet. Chem. 1997,
530, 255 ± 257.
[8] a) N. Kuhn, T. Kratz, D. Blaeser, R. Boese, Chem. Ber. 1995, 128, 245 ±
250; b) A. Schäfer, M. Weidenbruch, W. Saak, S. Pohl, J. Chem. Soc.
Chem. Commun. 1995, 1157 ± 1158.
[9] Phosphorus ± carbon triple bonds were obtained from a phosphini-
dene ± carbene compound: a) D. J. Berger, P. P. Gaspar, P. Le Floch, F.
Mathey, R. S. Grev, Organometallics 1996, 15, 4904 ± 4915; b) D.
Bourissou, P. Le Floch, F. Mathey, G. Bertrand, Org. Organomet.
Synth. 1999, 351 ± 357.
ꢀ
parent molecule HGe CH, which indicated that the germa-
vinylidene isomer Ge CH2 is 7 kcalmol 1 more stable than
:
1
trans-bent germyne, and 43 kcalmol more stable than the
linear germyne.[15] However, our results are in accordance
with the work of Apeloig and Karni in the field of silicon
chemistry, who predicted that bulky substituents are expected
to destabilize the vinylidene structure relative to the triple
bond.[16]
[10] a) A. Cowley, R. Jones, M. Mardones, J. Ruiz, J. Atwood, S. Bott,
Angew. Chem. 1990, 102, 1169; Angew. Chem. Int. Ed. Engl. 1990, 29,
1150 ± 1151; b) H. Schumann, W. Wassermann, A. Dietrich, J. Organo-
met. Chem. 1989, 365, 11 ± 18; c) H. Schumann, U. Hartmann, W.
Wassermann, Chem. Ber. 1991, 124, 1567 ± 1569; d) J. T. B. H. Jastr-
zebski, P. A. Van der Schaaf, J. B. Boerma, G. van Koten, M. C.
Zoutberg, D. Heijdenrijk, Organometallics 1989, 8, 1373 ± 1375.
[11] Crystal data for 2: C24H44GeN4Si, Mr 489.31, monoclinic, space
Experimental Section
All experiments were performed under a dry and oxygen-free argon
atmosphere. Solvents were dried by appropriate methods. Melting points
were determined in capillaries sealed under argon and are not corrected.
1: n-Butyllithium (4.2 mL, 1.6m in hexane) was added dropwise to ArBr
(2.0 g, 6.1 mmol) in THF (15 mL) at 788C, and the mixture was stirred for
20 min. A solution of GeCl2 ´ dioxane (1.4 g, 6.1 mmol) in THF (15 mL) was
then added at the same temperature, and the reaction mixture was stirred
for 30 min at room temperature. A solution of lithiotrimethylsilyldiazo-
methane (6.1 mmol) prepared from a solution of trimethylsilyldiazo-
methane (3.05 mL, 2m in hexane) and nBuLi (4.2 mL, 1.6m in hexane) in
THF (15 mL) was added dropwise to the above mixture at 788C, and the
solution was stirred at room temperature for 30 min. Solvents were
removed in vacuum, and the residue was dissolved in pentane. The mixture
was filtered, the solvents evaporated, and 1 was obtained as viscous oil
(1.98 g, 75% yield). 1H NMR (400.1 MHz, C7D8, TMS): d 0.55 (s, 9H,
Me3Si), 1.11 (t, 3J(H,H) 6.7 Hz, 12H, CH2CH3), 2.83 (q, 3J(H,H)
6.7 Hz, 8H, CH2CH3), 3.63, 3.75 (AB system, 2J(H,H) 14.2 Hz, 4H,
CH2), 7.10 ± 7.30 (m, 3H); 13C NMR (100.6 MHz, C7D8, TMS): d 0.40
(1J(13C,29Si) 26.6 Hz, CH3Si), 9.84 (CH2CH3), 24.49 (CN2), 45.31
(CH2CH3), 59.77 (CH2), 124.54 (m-C), 127.69 (p-C), 145.21 (o-C), 156.85
(ipso-C); 14N NMR (28.9 MHz, C7D8, MeNO2): d 110 (14Na), 14Nb signal
too weak to be observed; 29Si NMR (39.8 MHz, C7D8, TMS): d 0.98
group P21/c, a 10.3936(3), b 10.8900(3), c 24.2005(8) , b
3
99.247(1)8, V 2703.6(1) 3, Z 4, 1calcd 1.202 Mgm
,
F(000)
1
1048, l 0.71073 , T 193(2) K, m(MoKa) 1.194 mm
, crystal
dimensions 0.1 Â 0.6 Â 0.8 mm, 2.53 ꢁ q ꢁ 30.498; 22744 reflections
(8204 independent, Rint 0.0469) were collected at low temperature
on an oil-coated shock-cooled crystal on a Bruker-AXS CCD 1000
diffractometer. A semi-empirical absorption correction was employed
(Tmin 0.546246, Tmax 1.000000).[17] The structure was solved by
direct methods (SHELXS-97)[18], and 340 parameters were refined by
the least-squares method on F 2.[19] Maximum residual electron
density: 1.068 e 3, R1 (for F > 2s(F))0.0375 and wR20.0990
(all data) with R1SjFo j jF j SjF j and wR2(Sw(Fo2 Fc22/
/
c
o
Sw(Fo22)0.5. Crystallographic data (excluding structure factors) for the
structure reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publica-
tion no. CCDC-149434. Copies of the data can be obtained free of
charge on application to CCDC, 12 Union Road, Cambridge
CB21EZ, UK (fax: (44)1223-336-033; e-mail: deposit@ccdc.cam.
ac.uk).
.
.
(Me3Si); EI-MS (70 eV): m/z (%): 434 (21) [M ], 377 (2) [M
Et N2],
[12] a) We consider bond lengths close to the sum of the covalent radii for
the two elements involved to be normal; b) R. Chauvin, J. Phys. Chem.
1992, 96, 9194 ± 9197.
321 (100) [ArGe], 291 (42) [ArGe 2Me], 220 (52) [ArGe NEt2 Et],
177 (35) [ArGe 2NEt2]; IR (C6D6): nÄ 1994 cm 1 (CN2).
[13] For a review on carbene chemistry, see W. Kirmse in Carbene
Chemistry (Ed.: A. T. Blomquist), Academic Press, New York, 1971,
pp. 267 ± 362.
[14] D. Bethell, R. D. Howard, J. Chem. Soc. B 1969, 745 ± 748.
[15] S. M. Stogner, R. S. Grev, J. Chem. Phys. 1998, 108, 5458 ± 5464.
[16] Y. Apeloig, M. Karni, Organometallics 1997, 16, 310 ± 312.
[17] SADABS, Program for Absorption Correction, Bruker-AXS.
[18] G. M. Sheldrick, Acta Crystallogr. Sect. A 1990, 46, 467 ± 473.
[19] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure Refine-
ment, University of Göttingen, 1997.
2: The same procedure as for 1 was used for 2, which was recrystallized
from pentane at 208C (40% yield). M.p. 788C (decomp); 1H NMR
(400.1 MHz, C7D8, TMS): d 0.37 (s, 9H, Me3Si), 1.02 (d, 3J(H,H) 7.0 Hz,
12H, CH(CH3)2), 1.06 (d, 3J(H,H) 7.0 Hz, 12H, CH(CH3)2), 3.27 (sept,
3J(H,H) 7.0 Hz, 4 H, CH(CH3)2), 3.72 (s, 4H, CH2), 7.08 ± 7.17 (m, 3H,
ArH); 13C NMR (100.6 MHz, C7D8, TMS): d 0.04 (CH3Si), 20.63
(CH(CH3)2), 21.45 (CH(CH3)2), 30.15 (CN2), 51.20 (CH(CH3)2), 54.36
(CH2), 124.19 (m-C), 127.67 (p-C), 147.10 (o-C), 158.39 (ipso-C); 29Si NMR
(39.8 MHz, C7D8, TMS): d 0.06 (Me3Si); EI-MS (70 eV): m/z (%): 490
.
.
.
(12) [M ], 447 (4) [M
iPr], 419 (5) [M
iPr N2], 377 (100) [ArGe];
IR (C6D6): nÄ 2001cm 1 (CN2).
Received: September 11, 2000 [Z15784]
954
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