1604
Organometallics 1992, 11, 1604-1618
Polymeric Organosilicon Systems. 12. Synthesis and Anionic Ring-Opening Polymerization of 1,2,5,6-Tetrasilacycloocta-3,7-diynes Mitsuo Ishikawa, * , l a Takanori Hatano,la Yutaka Hasegawa,laTomoyuki Horio,la Atsutaka Kunai,la Akio Miyai,lb Takahiro Ishida,lb Tomitake Tsukihara,'*lb Toru Yamanaka," Tsuneaki Koike,lc and Jun Shioyald Department of Appiied Chemistty, Faculty of Engineering, Hiroshima University, Higashi-Hiroshima 724, Japan, Department of Industrial Chemistty, Faculty of Engineering, Tottori UniversiW, Koyama-minami 10 1, Tottori 680, Japan, Mitsui Petrochemical Industries, Ltd., Nagaura, Sodegaura, Chiba 299-02, Japan, and Sumltomo Electric Industries, Ltd., Shimaya, Konohanaku, Osaka 554, Japan Received June 4, 1991
Six 1,2,5,6-tetrasilacycloocta-3,7-diynes were synthesized by the reaction of the di-Grignard reagents of 1,2-diethynyldisilaneswith 1,2-dichlorodisilanes. The reaction of the di-Grignard reagent of 1,2-diethynyl-l,2-dimethyldiphenyldisilanewith 1,2-dichloro-l,2-dimethyldiphenyldisilanegave two isomers, r-l,t-2,t-5,c-6-tetramethyl-1,2,5,6-tetraphenyl-l,2,5,6-tetrasilacycloocta-3,7-diyne (cis-trans-lb) and rl,t-2,c-5,t-6-tetramethyl-1,2,5,6-tetraphenyl-l,2,5,6-tetrasilacycloocta-3,7-diyne (all-trans-lb)whose configuratio_nswere determined by an X-ray diffraction study. cis-trans-lb crystallizes in the trigonal space group R3 with cell dimensions a = b = 21.671 (6) A, c = 16.639 (2) A, a = = 90°, y = 120°, V = 6557 (3) A3, and.Ddd = 1.167 Mg/m3 (2= 9), while all-trans-lb crystallizes in the monoclinic space group P2Ja with cell dimensions a = 18.308 (6) A, b = 11.339 (3) A, c = 15.352 (4) A, a = y = 90°, = 94.50 (2)O, V = 3186 (2) A3, and Dcdcd = 1.106 Mg/m3 (2= 4). Treatment of 1,2,5,6-tetrasilacycloocta-3,7-diynes with a catalytic amount of n-butyllithiumin THF at room temperature afforded poly[(disilany1ene)ethynylenesl with high molecular weights. The reaction of poly[(1,2-dimethyldiphenyldisilanylene)ethynylene]( I C ) , whose molecular weight was determined to be 77 900, with a catalytic amount of n-butyllithium in THF at room temperature resulted in depolymerization of the starting polymer to give oligomers with M, = 1500. Treatment of poly[(tetraethyldisilany1ene)ethynylenel(Sc) with a catalyticamount of n-butyllithium under the same conditions led to redistribution to give the polymer which showed a very broad molecular weight distribution. Similarly,poly[(1,2-di-n-hexyldimethyldisilanylene)ethynylene] underwent redistribution in the presence of a trace of n-butyllithium, but the rate of the reaction was determined to be slow. Irradiation of a benzene solution of the poly[(disilany1ene)ethynylenesl with a low-pressure mercury lamp resulted in homolytic scission of silicon4icon bonds to give photodegradation products with low molecular weights. Irradiation of the f i b s prepared from the polymers in air also led to the scission of the siliconailicon bonds in the polymer backbone to give the products which have silanol and siloxy groups. Treatment of the films prepared from I C , 5c, and poly[(1,2-diethyldimethyldisilanylene)ethynylene]with antimony pentafluoride vapor afforded conducting films.
Introduction We have demonstrated that organosilicon polymers in which fie alternating arrangement of a &danylene unit and ?r-electronsystem is found in the polymer backbone we photoactive and show conducting properties when the polymers are doped by exposure to antimony pentafluoride vapor. Alternating polymers containing the disilanylene-?relectron system can readily be accomplished by the sodium condensation reaction of compounds involving two chlorosily1 groups attached to the ?r-electron system.24 However, the major problem of this method is, the lack of reproducibility for the product yields and molecular weights of the resulting polymers. In an attempt to develop a method that does not involve alkali-metal condensation for the preparation of the alternating copolymers, we discovered that 1,2,5,6-tetrasilacycloocta3,7-diynes undergo anionic ring-opening polymerization (1) (a) Hiroshima University. (b) Tottori University. (c) Mitsui Petrochemical Industries, Ltd. (d) Sumitomo Electric Industries, Co. Ltd. (2) Nate, K.; Ishikawa, M.; Ni, H.; Watanabe, H.; Saheki, Y. Organometallics 1987,6, 1673. (3) Ohshita, J.; Kanaya, D.; Ishikawa, M.; Yamanaka, T. J. Organomet. Chem. 1989, 369, Cl8. ( 4 ) Hong, H.; Weber, W. P. Polym. Bull 1989.22,363. ( 5 ) Hu, S.; Weber, W. P. Poly&. Bull. 1989,2I,133. (6) Ohshita, J.; Kanaya, D.; Ishikawa, M.; Koike. T.: Yamanaka, T. Macromolecules 1991,24,2106.
to give poly[ (disilany1ene)ethynylenesl in the presence of a catalytic amount of n-butyllithium in THF. We now wish to report in detail the synthesis and ring-opening polymerization of 1,2,5,6-tetrasilacycloocta-3,7-diynes and Some Properties of the resulting Poly[ (disi1anylene)-
Results and Discussion Synthesis. The first strained eight-membered cyclic (disilanylene)ethynylene, octamethyl-1,2,5,6-tetrasilacycloocta-3,7-diyne has been synthesized by Sakurai and his co-workers from the thermal and photochemical ring contraction of permethylated 1,2,3,6,7-pentasilacyclonona-4,8-diyne.I Recently, Iwahara and West have reported the preparation of three tetrasilacyclooctadiyne derivatives, 1,1,2,2,5,5,6,6-octamethyl-, 1,1,2,2,5,5,6,6octa-n-butyl-, and 1,2,5,6-tetra-n-butyltetramethyl1,2,5,6-tetrasilacycloocta-3,7-diyne in high yields? Their method involves the reaction of the di-Grignard reagents prepared from 1,2-diethynyldisilanesand ethylmagnesium bromide with 1,2-dichlorodisilanes. We have also found that the tetrasilacyclooctadiynescan readily be prepared by the reaction of the di-Grignard reagents of 1,2-diethynyldisilanes with 1,2-di~hlorodisilanes.~~ (7) Sakurai, H.; Nakadaira, A.; Hosomi, A.; Eriyama, Y.; Kabuto, C. J . Am. Chem. SOC.1983,105, 3359. (8) Iwahara, T.; West, R. J. Chem. SOC.,Chem. Commun. 1988,954.
0276-7333/92/2311-1604$03.00/00 1992 American Chemical Society
Organometallics, Vol. 11, No. 4, 1992 1605
Polymeric Organosilicon Systems Scheme I R1 R i I
I
A1
A2
R2R1Si-
I ) iso-PrMgCi
HCIC-Si-Si-C-CH
H15
2) ClR'R2SiSiR2RlCl
*
C=C-SiR1R2
Rkiii- c I c - i i R i R i
la,RI-Ph,R2-Me
Ib.R1-Ph.R2-Me (37% yield) ( cis-trans 20% + all-trans 17% )
2a,R1-E1,R2=Me
2b.R1-Et,R2-Me
3a.R1-Bu.R2-Me
3b,RI-Bu,R2-Me (54% yield)
4a,RI-Hex,R2=Me
4b,Ri=Hex.R'-Mc (52% yield)
5a.R'=R2=E1
Sb,R1=R'-E1 (50% yield)
.
n.BuLi (0.5.lmol%)
Si- Si-
1 R2I
I
R2
(50% yield)
C= C
Jn
Ic,R1-Ph.R2=Me cis-trans (14% yield) ail.trans
(32% yeld)
2c,R'=E1,R2=Me (88% yield)
Figure 1. Molecular structure of cis-trans-lb with the atomic numbering system. The harmonic parts of the displacement ellipsoids for non-hydrogen atoms are drawn a t the 50% probability level.
3c,RI=Bu.R2=Me (94% yield)
hexyltetramethyl-1,2,5,6-tetrasilacyclo~ta-3,7-diyne (4b), and 1,1,2,2,5,5,6,6-octaethyl-1,2,5,6-tetrasilacyclooc~-3,7diyne (5b) in 50,54, 52, and 50% yields, respectively. 'H The starting 1,2-diethynyldisilanes were synthesized by and 13CNMR spectra of 2b-4b appear as if only one isomer is present in the isolated product (see Experimental the reaction of ethynylmagnesiumbromide obtained from ethylmagnesium bromide and acetylene in THF, with Section). Tetrasilacyclooctadiyne 2b thus obtained is colorless crystals but melts at 30-32 "C. Unfortunately, 1,2-dichlorodisilanes. Using this method, 1,Bdiethynylno single crystal, analogous to cis-trans-lb or all-trans-lb, 1,2-dimethyldiphenyldisilane(la),9b1,2-diethyl-1,2-dicould be obtained by fractional recrystallization, because ethynyldimethyldisilane (2a), 1,2-di-n-butyl-1,2-diof the low melting point of 2b. Compounds 3b and 4b are ethynyldimethyldisilane* (3a), 1,2-diethynyl-1,2-di-ncolorless liquids, and therefore, we could not clarify hexyldimethyldisilane (4a), and tetraethyl-l,2-diethynylwhether or not the products 2b-4b consist of a mixture disilane (5a) were synthesized in 82,87,83,48, and 84% of isomers. However, on the basis of the fact that the yields, respectively. Compounds la-4a were isolated as a mixture of dl and meso isomers, and the mixture of dl chemical shifts of the 'H and I3C NMR spectra of cistrans-lb are the same as those of all-trans-lb, the products and meso isomers was used for the synthesis of the tet2b, 3b, and 4b are thought to be a mixture consisting of rasilacyclooctadiynes. The reaction of the di-Grignard two isomers, analogous to cis-trans-lb and all-trans-lb. reagents prepared from la-5a and 2 equiv of isopropylIn 'H and 13C NMR spectra for 2b-4b, the chemical shifts magnesium chloride in THF, with the corresponding 1,2dichlorodisilanes afforded 1,2,5,6-tetrasilacycloocta-3,7- for two isomers would be accidentally overlapping. The structures of compounds 2b-5b were confirmed by diynes lb-5b in 37-54s yields (Scheme I). mass, IR,and 'H and 13CNMR spectroscopic analyses (see In the reaction of the di-Grignardreagent prepared from la with 1,2-dichloro-1,2-dimethyldiphenyldisilane, two Experimental Section). were isolated X-ray Analysis of cis-trans-lb and all-trans-lb. isomers of 1,2,5,6-tetrasilacyclmta-3,7-diyne as white crystals in 20 and 17% yields, respectively, after The molecular structures of cis-trans-lb and all-trans-lb fractional recrystallization of the reaction mixture. Conwere determined by the X-ray crystal structural analysis.l0 cis-trans-lb which is obtained by recrystallization from figurations of these two isomers were verified by an X-ray crystallographic analysis. One isomer which crystallized benzene belongs to the trigonal space group R3 with cell dimensions a = b = 21.671 (6) A, c = 16.639 (2) A, a = p from benzene and melts at 202-203 "C was identified as = W", y = 120°, V = 6557 (3) A3, and DdCd = 1.167 Mg/m3 r-l,t-2,t-5,~-6-tetramethyl-l,2,5,6-tetraphenyl-l,2,5,6-tet(Z = 9), while all-trans-lb crystallizes in the monoclinic rasilacyclmta-3,7-diyne (cis-trans-lb), that is, two phenyl space group P2 /a with cell dimensions a = 18.308 (6) A, groups on an Si-Si moiety are located in a trans fashion, b = 11.339 (3) c = 15.352 (4) A, a = y = 90°, p = 94.50 but two phenyls on an Si-C=C-Si group are cis each other. The other isomer which crystallized from benz(2)", V = 3186 (2) A3, and Dcdcd= 1.106 Mg/m3 (Z = 4). ene-hexane and melts at 155-156 "C was identified as The experimental conditions, crystal data, and summaries of structural refinements for the two compounds are listed r-l,t-2,~-5,t-6-tetramethyl-1,2,5,6-tetraphenyl-l,2,5,6-tetin Table I. The crystal structures of both compounds were rasilacyclooda-3,7-diyne(all-trans-lb) in which all phenyl solved by MULTAN" and refined by the block-diagonal groups are located in a trans fashion (see below). least-squares method.12 Four large reflections of cisSimilar reactions of the di-Grignard reagents prepared from 2a-5a with the corresponding 1,2-dichlorodisilanes trans-lb, (3,-2,2), (5,-3,-1), (7,-5,3), and (7,-5,6), affected gave 1,2,5,6-tetraethyltetramethyl-1,2,5,6-tetrasilacyclo- seriously by extinction or absorption were excluded from octa-3,7-diyne (2b), 1,2,5,6-tetra-n-butyltetramethyl- the refinement. The final fractional coordinates and 1,2,5,6-tetrasilacycloocta-3,7-diyne* (3b), 1,2,5,6-tetra-n4c.R'-Hex,R2=Me (75% yield) 5 c R1=R2-Et (90% yield)
A,
(9)(a) Ishikawa, M.; Hasegawa, Y.; Hatano, T.; Kunai, A. Organometallics 1989,8,2741. (b) Ohshita, J.; Matsuguchi, A.; Furumori, K.; Ishikawa, M.; Yamanaka,T.; Koike, T.; Shioya, J. Submitted Hong, R.-F.; for publication in Macromolecules. (c) Ohshita, J.; Furumori, K.; Ishikawa, M. Organometallics 1989,8, 2084.
(10)X-ray crystallographic analysis of 1,1,2,2,5,5,6,6-octamethyl1,2,5,6-tetrasilacycloocta-3,7-diyne has been reported; see ref 7. (11)Germain, G.; Main, P.; Woolfson, M. M. Acta Crystallogr. 1971, A27, 369. (12)Ashida, T. HBLS-V, Universal CrystallographicComputing System, Osaka University, 1973;p 55.
1606 Organometallics, Vol. 11, No. 4, 1992 Table I. Crystal Data, Experimental Conditions and Summaries of Structural Refinement for cis-trans-lb and a l l -trans- l b cis-trans-1 b all-trans- l b mol formula mol w t space group cell dimens
SiaCB,Hs9 _. 528.95
SidC3ZH32
R9
mla
528.95
21.671 (6) 21.671 (6) 16.639 (2) c, A 90.0 a,deg 90.0 P, deg 120.0 6557 (3) 1.167 Dcalcd, Mg/m3 cryst size, mm 0.2 X 0.2 X 0.5 prismatic cryst habit colorless cryst color g, mm" 1.98 diffractometer Rigaku AFC5 temp, K 298 wavelength, A 1.5418 (Cu Ka) monochromator graphite crystal 8-28 scan type scan speed, deg/min 8 4 < 28 < 120 scan width, deg diffraction geometry symmetrical A range of h,k,l h 0 < h < 14" k 0 < k < 14" 1 -14 < l < 14" no. of unique reflns 2265 no. of obsd reflns 1904 (F,> 347,)) 0.055 140 0.079 R 0.103 R,b S.' 1.84 0.58 max Ap, ef A3 -0.42 min Ap, e/A3 a, A
b, A
%GO)
18.308 (6) 11.339 (3) 15.352 (4) 90.0 94.50 (2) 90.0 3186 (2) 1.106 0.5 X 0.5 X 0.6 prismatic colorless 0.20 Rigaku AFC4 298 0.7107 (Mo Ka) graphite crystal 8-28 8 3 < 28 < 45 symmetrical A O
