2139
Organometallics 1996, 14, 2139-2141
Reaction of a Germylene with Ethylene: A Stable Digermacyclobutane via a Germirane Intermediate Harunobu Ohgaki, Yoshio Kabe, and Wataru Ando* Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki 305, Japan Received December 1, 1994@ Summary: 2,2-Digermacyclobutane (2) is formed by reaction of a stable germylene (1) with ethylene. The crystal structure of 2 has been determined by singlecrystal X-ray diffraction. The IH NMR spectrum of the reaction mixture revealed the presence of a germirane having no substituents on the ring carbon.
R'GeN
R,Ge:
+ H2C=CH2
1
R
+1
1\
-
u
R=(SiMe3),CH
3 ,R G , e-Ge,
/
R
R u
Numerous studies have been concerned with the R synthesis of small-ring compounds containing the heavier group 14 e1ements.l Recently we have reported the first L substituent-stabilized germiranes with alkylidene and acyl groups on the ring carbons.2 However, the reaction The results of the X-ray structure analysis of 2 are of simple olefins such as ethylene, propylene, 2-butene, shown in Figure 1. The molecule possesses an apetc. with a germylene remained to be studied. We atproximate CZaxis which bisects both C-C and Ge-Ge tempted reactions of a stable germylene3with propylene bonds. The CZGe2 trapezoidal core deviates from plaand 2-butene, but the expected products were not denarity with a C-Ge-Ge-C torsion angle of 12.7'. This tected. On the other hand, the reaction of a stable germto the sterically demanding (Me3Si)zCH deviation is due ylene with ethylene afforded a 1,2-digermacyclobutane. groups on the two germanium atoms. When ethylene gas was bubbled into a toluene soluIn order to detect spectral changes associated with tion of the stable germylene (1; 1.70 mmol), the yellow the first stage of the reaction, W - v i s spectra were color of 1 was immediately discharged. The mixture measured immediately after the reaction of germylene was stirred in excess ethylene at room temperature for 1 with ethylene. No significant absorptions for 1 at 418 24 h. After removal of the solvent, purification of the 2 at 278 nm were observed. However, nm nor for residue by silica gel column chromatography (hexane) removal of excess ethylene from the mixture by bubbling followed by recrystallization in hexane gave colorless argon caused appearance of a peak at 418 nm. These crystals of 172-digermacyclobutane (21, an air- and findings indicate that an intermediate species is in moisture-stable compound in 55% yield. The 'H NMR thermal equilibrium in solution with 1 and the ethylene spectrum of 2 exhibits signals due to one CH and two fragment. This species could be either the germyleneSiMe3 groups of the (Me3Si)ZCH substituents and to one ethylene n complex or the germirane. GeCHz group a t 2.19 ppm, and the 13C NMR spectrum An NMR study of the reaction mixture at the first exhibits a signal due to the GeCHz groups at 27.2 ~ p m . ~ stage of the reaction of 1 with excess ethylene revealed These observations support the presence of diastethe presence of only one species, to which we assign the reotopic (Me3Si)zCHgroups and equivalent CH2 groups. germirane (3)structure shown in Figure 2. The peaks Abstract published in Advance ACS Abstracts, April 1, 1995. (1)(a) Review: Ando, W.; Kabe. Y. Small-Ring Organo-Silicon, Germanium and Tin Comnounds. Adu. Strain O w . Chem. 1993. 3 . 59. (b) Siliranes: Delker, 6.L.; Wang, Y.; Stucky, 6 D., Jr.; Lambert; R. L.;Hass, C. K.; Seyferth, D. J . Am. Chem. SOC.1976,98, 1779. (c) Seyferth, D.; Annarelli, D. C.; Vick, S. C.; Ducan, P. J. Organomet. Chem. 1980,201,179. (d) Ando, W.; Fujita, M.; Yoshida, H.; Sekiguchi, A. J. Am. Chem. SOC.1988,110, 3310. (e) Boudjouk, P.; Black, E.; Kumarathasan, R. Organometallics 1991,10,2095. (D Pae, D. H.; Xiao, 1991, 113, 1281. M.; Chiang, M. Y.; Gasper, P. P. J . Am. Chem. SOC. (g) Alkylidene-siliranes: Saso, H.; Ando, W.; Ueno, K. Tetrahedron 1989,45, 1929. (h) Bis(alky1idene)silirane: Yamamoto, T.; Kabe, Y.; Ando, W. Organometallics 1993, 12, 1996. (i) Silirenes: Conlin, R. T.; Gaspar, P. P. J . Am. Chem. Soc. 1976,98, 3715. (i) Seyferth, D.; Annarelli, D. C.; Vick, S. C. J. Am. Chem. Soc. 1976, 98, 6382. (k) 1977, Sakurai, H.; Kamiyama, Y.; Nakadaira, Y. J. Am. Chem. SOC. 99, 3879. (1) Hirotsu, K.; Higuchi, T.; Ishikawa, M.; Sugisawa, M.; Kumada, M. J. Chem. SOC.,Chem. Commun. 1982,726. (m) Seyferth, D.; Annarelli, D. C.; Vick, S. C. J. Organomet. Chem. 1984,272, 123. (n) Germirenes: Krebs, A.; Bemdt, J. Tetrahedron Lett. 1983,24,4083. (0)Egorov, M. P.; Kolesnikov, S. P.; Struchkov, Y. T.; Antipin, M. Y.; Sereda, S. V.; Nefedov, 0. M. J . Organomet. Chem. 1985, 290, C27. (p) Stannirenes: Sita, L. R.; Bickerstaff, R. D. J.Am. Chem. SOC.1988, 110, 5208. (2) Ando, W.; Ohgaki, H.; Kabe, Y. Angew. Chem., Int. Ed. Engl. 1994, 33, 659 and references cited therein. (3)Goldbeg, D. E.; Hitchcock, P. B.; Lappert, M. F.; Thomas, K. M.; Thorne, A. J.; Fjeldberg, T.; Haaland, A.; Schilling, B. E. R. J. Chem. SOC.Dalton Trans. 1986, 2387. @
LRMS (mlz) 474 (M+),459 (M+-- Me). ( 5 ) Crystal data of 2: fw 810.84, monoclinic, a
= 8.901(1) A,b = 13.948(2) A,c = 37.645(4) A, 8 , = 90.43(1)", V = 4673.5 A3, space group o = 14.9 cm-l, e(ca1cd) = 1.15 g/cm3. The 3674 P2,/c, Z = 4, ~ ( M Ka) independent reflections (20 5 50"; lFo21 2 3olFo21)were measured on an Enraf-Nonius CAD4 diffractometer using Mo Ku irradiation and an 0-28 scan. An empirical absorption correction based on a series of 2/, scans were applied to the data 0.83l1.00. The structure was solved by direct methods, and hydrogen atoms were added to the structure factor calculations but their positions were not refined anisotropically to R = 0.067 (R,= 0.086). (6) In stannirene and a thiastannirane thermal equilibria between stannylene and acetylene or thioketene were reported (a) Boatz, J. A.; Gordon, M. S.; Sita, L.R. J.Phys. Chem. 1990,94,5488. (b) Ohtaki, T.; Kabe, Y.; Ando, W. Organometallics 1993, 12, 4.
0276-733319512314-2139$09.0010 0 1995 American Chemical Society
Communications
2140 Organometallics, Vol. 14, No. 5, 1995
c5 1
!
CH3 CH3
x I
x
P Figure 1. Crystal structure of 2 (ORTEP). Selected bond lengths (A)and angles (deg): Ge(lI-Ge(2) = 2.554(2),Ge(1)-C(5) = 2.01(1), Ge(2)-C(6) = 2.01(1),C(5)-C(6) = 1.57(2), Ge(1)-C(l) = 2.04(1), Ge(l)-C(2) = 2.03(1), Ge(2)C(3) = 2.04(1),Ge(2)-C(4) = 2.00(1); Ge(l)-Ge(2)-C(6) = 74.7(4), Ge(2)-Ge(l)-C(5) = 75.3(4), Ge(l)-C(5)-C(6) = 102.2(8),Ge(2)-C(6)-C(5) = 103.1(8);torsion angle C(5)Ge(l)-Ge(2)-C(6) = 12.74. t
(7) (a) Mochida, K.; Kikkawa, H.; Nakadaira, Y. Chem. Lett. 1988, 1089. (b)Bobbitt,K. L.; Maloney, V. M.;Gasper, P. P. Organometallics 1991,10, 2772.
l
l
0
CH X
0
1 .o
were assigned by DEP" and C-H COSY spectra (ppm): CHSiMe3 (lH, -0.41; 13C, 2.71, GeCH2 (lH, 0.78; 13C, 2.51, SiCH3 (lH, 0.18; 13C, 3.0h4 A single SiMe3 resonance is consistent with a highly symmetrical structure (Cd such as that of the germirane, not with a n complex. In the latter the two substituents on the Ge atom bend inward to the ring skeleton in order to maximize the overlap between the vacant p orbital of 1 and the n orbital of ethylene. Furthermore, 13C NMR signals due to the ring carbons of the intermediate exhibited a n upfield shift similar to that of cyclopropane (6 -2.6) and 1,l-di-tert-butylsilirane(6 -5.0).le The 1J(13C-1H) coupling constant was estimated to be 153 Hz by 'H-coupled 13C spectra, which was large and comparable to that in cyclopropane ( J = 160 Hz) and 1,l-di-tert-butylsilirane( J = 154 Hz).le When the reaction mixture was allowed to stand for a few days, the intermediate germirane (3)gradually was converted to 2, as shown in Figure 2. However, attempts to isolate 3 was unsuccessful. Removal of ethylene and solvent resulted in the disappearance of 3. The photochemical sensitivity of the Ge-Ge bond7 results in changes in the UV-vis spectrum upon irradiation (> 300 nm) using a high-pressure mercury lamp. Loss of the absorbance due to 2 a t 278 nm was
CH
CH2
l
l
l
0.5
l
l
l
ppm
l
l
0.0
l
l
l
l
1
-0.5
Figure 2. lH NMR spectra of 1 and C2& in benzene&: (0)3;(A) 2; ( x ) KMe3Si)&HIzGeH(OH) as a minor product derived from 1 and adventious yater. Measuring times of the spectra are as follows: (bottom) aRer 30 min; (middle) after 6 h; (top) aRer 24 h. observed with concomitant growth of peaks due to free germylene 1 at 418 nm. Similarly, photolysis of 2 in carbon tetrachloride afforded 1,4-digerma-l,Cdichlo~ photolysis in 2,3robutane (4) q ~ a n t i t a t i v e l y ,and dimethyl-1,3-butadiene yielded 1-germacyclopent-3-ene (51 q ~ a n t i t a t i v e l y .These ~ results indicated that Ge-
Ge bond dissociation is the dominant primary photoprocess.8 The diradical which is formed reacts with (8)(a) Kira, M.; Sakamoto, K.; Sakurai, H. J.Am. Chem. SOC.1983, 105, 1469. (b) Sakurai, H.; Sakamoto, K.; Kira, M. Chem. Lett. 1984,
1213. (c) Sakurai, H.; Sakamoto, K.; Kira, M. Chem. Lett. 1984,1379. (d) Sakurai, H.;Sakamoto, K.; Kira, M. Chem. Lett. 1987, 983.
Organometallics, Vol. 14,No.5, 1995 2141
Communications carbon tetrachloride more rapidly than does 2,3-dimethyl-l,3-butadiene. On the other hand, in the presence of the butadiene, with which the diradical reacts only slowly, it undergoes germylene extrusion. The latter reacts with the butadiene to give the l-germacyclopent-3-ene.
Acknowledgment. We are grateful to Asai Germanium Institute and Shin-Etsu CooLtd. for their gifts of trichlorogermane and chlorosilanes. This work was supported by a Grant-in-Aid for Scientific Research
from the Ministry of Education, Science and Culture of Japan. Supplementary Material Available: Text describing crystallographic procedures, tables of crystallographic data, atomic coordinates and thermal parameters, and bond length and angles for 2, a figure showing the ORTEP structure, and figures showing UV-vis spectra and 'H, I3C, DEPT, lHdecoupled 13C, and C-H COSY NMR spectra of 3 (42 pages). Ordering information is given on any current masthead page.
OM940918X
