Synthesis of organosilicon macrocycles. Palladium-catalyzed ring-enlargement oligomerization of cyclic disilanes via Si-Si σ-bond metathesis

Article abstract of DOI:10.1021/om950883g

Bis(tert-alkyl isocyanide)palladium(0) complexes catalyzed a ring-enlargement oligomerization of 1,1,2,2-tetramethyl-1,2-disilacyclopentane through Si-Si σ-bond metathesis to give cyclic oligomers up to the 40-membered octamer. The cyclic structure of the tetramer was established by the single-crystal X-ray diffraction method, which showed that the four Si-Si bonds of the tetramer were in a close to parallel arrangement. Reactivities of the dimer, trimer, and tetramer in the presence of bis(tert-butyl isocyanide)palladium(0) revealed that the present Si-Si σ-bond metathesis proceeded reversibly, in which the -Me₂Si(CH₂)₃SiMe₂-unit of the disilacyclopentane was successively inserted into the Si-Si bond of the oligomer to give higher oligomers. The intermediary 6-membered bis(organosilyl)bis(tert-alkyl isocyanide)palladium complex, which arose from oxidative addition of the disilacyclopentane onto bis(tert-alkyl isocyanide)palladium(0), was isolated and characterized by the single-crystal X-ray method. The insertion of the -Me₂Si(CH₂)₃SiMe₂- unit also occurred with linear disilanes and digermane to give linear oligomers. The cyclic trimer and tetramer reacted with 2,6-diisopropylphenyl isocyanide in the presence of Pd(OAc)₂ to afford an 18-membered-ring triimine and 24-membered-ring tetraimine, respectively, in which the isocyanides were inserted into all the Si-Si linkages. Oxidation of the cyclic oligomers with trimethylamine oxide gave the corresponding cyclic oligo(disiloxane) species in quantitative yields. Unexpected polymerization of the disilacyclopentane occurred in the presence of the (η⁵-cyclopentadienyl)(η³-allyl)palladium(II) catalyst to give poly(Me₂Si(CH₂)₃SiMe₂) compounds with high molecular weights.

Full text of DOI:10.1021/om950883g

2170
Organometallics 1996, 15, 2170-2178
Syn th esis of Or ga n osilicon Ma cr ocycles.
P a lla d iu m -Ca ta lyzed Rin g-En la r gem en t Oligom er iza tion
of Cyclic Disila n es via Si-Si σ-Bon d Meta th esis
Michinori Suginome, Hideaki Oike, Philippa H. Shuff, and Yoshihiko Ito*
Department of Synthetic Chemistry and Biological Chemistry, Faculty of Engineering,
Kyoto University, Kyoto 606-01, J apan
Received November 13, 1995X
Bis(tert-alkyl isocyanide)palladium(0) complexes catalyzed a ring-enlargement oligomer-
ization of 1,1,2,2-tetramethyl-1,2-disilacyclopentane through Si-Si σ-bond metathesis to give
cyclic oligomers up to the 40-membered octamer. The cyclic structure of the tetramer was
established by the single-crystal X-ray diffraction method, which showed that the four Si-
Si bonds of the tetramer were in a close to parallel arrangement. Reactivities of the dimer,
trimer, and tetramer in the presence of bis(tert-butyl isocyanide)palladium(0) revealed that
the present Si-Si σ-bond metathesis proceeded reversibly, in which the -Me2Si(CH2)3SiMe2-
unit of the disilacyclopentane was successively inserted into the Si-Si bond of the oligomer
to give higher oligomers. The intermediary 6-membered bis(organosilyl)bis(tert-alkyl
isocyanide)palladium complex, which arose from oxidative addition of the disilacyclopentane
onto bis(tert-alkyl isocyanide)palladium(0), was isolated and characterized by the single-
crystal X-ray method. The insertion of the -Me2Si(CH2)3SiMe2- unit also occurred with
linear disilanes and digermane to give linear oligomers. The cyclic trimer and tetramer
reacted with 2,6-diisopropylphenyl isocyanide in the presence of Pd(OAc)2 to afford an 18-
membered-ring triimine and 24-membered-ring tetraimine, respectively, in which the
isocyanides were inserted into all the Si-Si linkages. Oxidation of the cyclic oligomers with
trimethylamine oxide gave the corresponding cyclic oligo(disiloxane) species in quantitative
yields. Unexpected polymerization of the disilacyclopentane occurred in the presence of the
(η5-cyclopentadienyl)(η3-allyl)palladium(II) catalyst to give poly(Me2Si(CH2)3SiMe2) com-
pounds with high molecular weights.
In tr od u ction
We have reported that bis(tert-butyl isocyanide)-
palladium(0) catalyzes a selective intramolecular Si-
Si σ-bond metathesis of some bis(disilanyl)methanes.6
The use of tert-alkyl isocyanide ligands on palladium
was crucially important for the activation of the Si-Si
bonds.7 On the basis of this activation, we recently found
that a catalytic amount of bis(tert-butyl isocyanide)-
palladium(0) induced intermolecular Si-Si σ-bond me-
tathesis of 1,1,2,2-tetramethyl-1,2-disilacyclopentane to
lead to ring-enlargement oligomerization that gave
macrocycles with regularly arranged Si-Si bonds.8
Herein, we describe in full detail the oligomerization of
the disilacyclopentane, in which a cyclic bis(organosilyl)-
bis(tert-alkyl isocyanide)palladium(II) complex is in-
volved as an intermediate. We also present the syn-
thesis of linear oligo- and poly(disilanes) by palladium-
catalyzed reactions of the five-membered cyclic disilane.
The cyclic oligomers thus prepared were further elabo-
rated by insertion reactions and oxidation of the Si-Si
linkages to give new functionalized organosilicon macro-
cycles.
Much attention has been focused on the design and
synthesis of organic macrocycles containing heteroatoms
and functional groups as functional molecules.1 Intro-
duction of electropositive elements such as group 14
metals instead of electronegative elements into organic
macrocycles with appropriate arrangement may lead to
the development of new functional molecules. Espe-
cially, in view of the intriguing chemical and physical
properties of Si-Si σ-bonds,2 an efficient synthesis of
macrocycles with regularly arranged Si-Si bonds may
be desired. Palladium-catalyzed Si-Si σ-bond metath-
esis of cyclic disilanes seemed to provide a convenient
method for preparation of macrocycles containing Si-
Si bonds in the ring. However, palladium(0)-phosphine
catalysts have been successfully applied only to cy-
clodimerization of cyclic four- and five-membered di-
silanes through the Si-Si σ-bond metathesis.3-5
X Abstract published in Advance ACS Abstracts, April 1, 1996.
(1) Vo¨gtle, F. Supramolecular Chemistry; Wiley: Chichester, U.K.,
1991; pp 9-128, and references therein.
(2) (a) West, R. In The Chemistry of Organic Silicon Compounds;
Patai, S., Rappoport, Z., Eds.; Wiley: Chichester, U.K., 1989; Chapter
19. (b) Miller, R. D.; Michl, J . Chem. Rev. 1989, 89, 1359-1410. (c)
Schubert, U. Angew. Chem., Int. Ed. Engl. 1994, 33, 419-421 and
references therein.
(3) For a five-membered cyclic disilane, see: Tamao, K.; Hayashi,
T.; Kumada, M. J . Organomet. Chem. 1976, 114, C19-21.
(4) For four-membered cyclic disilanes, see: (a) Kusukawa, T.; Kabe,
Y.; Ando, W. Chem. Lett. 1993, 985-988. (b) Kusukawa, T.; Kabe, Y.;
Nestler, B.; Ando, W. Organometallics 1995, 14, 2556-2564.
(5) For linear disilanes, see: Sakurai, H.; Kamiyama, Y.; Nakadaira,
Y. J . Organomet. Chem. 1977, 131, 147-152.
(6) Suginome, M.; Oike, H.; Ito, Y. Organometallics 1994, 13, 4148-
4150.
(7) For bis-silylation catalyzed by tert-alkyl isocyanide-palladium
complexes: (a) Ito, Y.; Suginome, M.; Murakami, M. J . Org. Chem.
1991, 56, 1948-1951. (b) Murakami, M.; Suginome, M.; Fujimoto, K.;
Nakamura, H.; Andersson, P. G.; Ito, Y. J . Am. Chem. Soc. 1993, 115,
6487-6498. (c) Suginome, M.; Matsumoto, A.; Nagata, K.; Ito, Y. J .
Organomet. Chem. 1995, 499, C1-C3. (d) Suginome, M.; Yamamoto,
Y.; Fujii, K.; Ito, Y. J . Am. Chem. Soc. 1995, 117, 9608-9609 and
references therein.
(8) Preliminary communication: Suginome, M.; Oike, H.; Ito, Y. J .
Am. Chem. Soc. 1995, 117, 1665-1666.
0276-7333/96/2315-2170$12.00/0 © 1996 American Chemical Society

Synthesis of Organosilicon Macrocycles
Organometallics, Vol. 15, No. 8, 1996 2171
Ta ble 1. Oligom er iza tion of 1a in th e P r esen ce of (RNC)2P d 0 (2) in Ben zen e-d 6
ratio of oligomers 3a n , %
time (days),
temp (°C)
total %
yield
entry no.
catalyst 2
isocyanide
t-BuNC
t-BuNC
t-BuNC
n ) 2
n ) 3
n ) 4
n ) 5
n ) 6
n ) 7
n ) 8
1
2a
2a
2a
2b
6, 50
6, 80
6, 80
6, 80
9
26
32
10
44
41
44
24
30
22
18
26
12
7
6
5
4
0
0
0
66
53
41
62
2a
3b
4
15
10
8
6
NC
5
2c
4, 80
81
19
0
27
NC
6
7
8
2d
2e
2f
i-PrNC
2,6-XyNC
6, 50
6, 50
6, 50
50
91
100
40
9
0
10
0
0
50
46
46
t-Bu
NC
OTBS
t-Bu
a
b
Addition of t-BuNC (1 equiv based on 2a ). Addition of t-BuNC (2 equiv based on 2a ).
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for 3a 4
Bond Distances
Si(1)-Si(1′)
C(2)-C(3)
2.352(2)
1.531(5)
1.886(4)
1.869(4)
1.500(6)
2.366(2)
Si(1)-C(2)
C(3)-C(4)
Si(5)-Si(6)
C(7)-C(8)
C(9)-Si(10)
1.882(4)
1.530(4)
2.356(1)
1.589(6)
1.858(5)
C(4)-Si(5)
Si(6)-C(7)
C(8)-C(9)
Si(10)-Si(10′)
Bond Angles
Si(1′)-Si(1)-C(2)
C(2)-C(3)-C(4)
C(4)-Si(5)-Si(6)
Si(6)-C(7)-C(8)
110.7(1) Si(1)-C(2)-C(3
115.0(3) C(3)-C(4)-Si(5)
113.0(1) Si(5)-Si(6)-C(7)
112.7(2) C(7)-C(8)-C(9)
115.6(2)
115.8(3)
112.6(1)
115.2(3)
C(8)-C(9)-Si(10) 114.1(3) C(9)-Si(10)-Si(10′) 115.3(2)
Sch em e 1
F igu r e 1. ORTEP drawing of the tetramer 3a 4 (30%
probability). Hydrogen atoms are omitted for clarity.
Resu lts a n d Discu ssion
R in g-E n la r gem en t Oligom er iza t ion of Cyclic
Disila n es. 1,1,2,2-Tetramethyl-1,2-disilacyclopentane
(1a ) was reacted in the presence of 1 mol % of (t-
BuNC)2Pd0 (2a ) in C6D6 under argon in an NMR sample
tube fitted with a rubber septum (eq 1; Table 1, entry
1). Though no reaction took place at room temperature,
various isocyanides examined, tert-alkyl isocyanides
except for 1,1,2,2-tetramethylpropyl isocyanide (in cata-
lyst 2c), which might be too bulky for the reaction to
proceed, were the ligands of choice, giving higher
oligomers (entries 4 and 5). Use of sec-alkyl iso-
cyanide as well as aryl isocyanides resulted in formation
of the oligomers only up to the tetramer 3a 4 (entries
6-8).
The yields of the oligomers were largely improved by
carrying out the reaction in a sealed tube under higher
concentration (see Experimental Section). Thus, in the
presence of 2a , the mixture of oligomers 3a n was
obtained in 93% total yield, consisting of the dimer 3a 2
(3%), trimer 3a 3 (32%), tetramer 3a 4 (34%), pentamer
3a 5 (14%), hexamer 3a 6 (6%), heptamer 3a 7 (3%), and
octamer 3a 8 (1%) (Scheme 1).
heating the mixture at 50 °C resulted in slow conversion
of 1a into a mixture of oligomeric products, which
included the literature-known cyclic dimer 3a 2. After
6 days at this temperature, the oligomeric products were
subjected to gel permeation chromatography to separate
and isolate the cyclic oligomers 3a n up to a 30-
membered hexamer. The cyclic structure of the tet-
ramer 3a 4 was established by single-crystal X-ray dif-
fraction, which showed that the four Si-Si bonds in the
ring were in a nearly parallel arrangement (Figure 1
and Table 2). The oligomerization was significantly
retarded by addition of a small amount (1 or 2 equiv
based on palladium) of tert-butyl isocyanide, although
the reaction at 80 °C gave the cyclic oligomers in nearly
the same distribution (entries 2 and 3). Among the
Unlike the reaction of 1a , the cyclic disilanes 1b-g
showed much lower reactivities. 1,2-Disilacyclopentane
1b gave dimer 3b2 (50% yield, 3:3:2:2 mixture of four

2172 Organometallics, Vol. 15, No. 8, 1996
Suginome et al.
Sch em e 2
F igu r e 2. ORTEP drawing of 4b (30% probability). One
of the two orientations of the disordered C(18) atom is
shown. Hydrogen atoms are omitted for clarity.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for 4b
Bond Distances
Pd(1)-Si(2)
Si(2)-C(7)
Si(2)-C(17)
N(3)-C(5)
2.358(5)
1.88(3)
1.89(3)
Pd(1)-C(4)
Si(2)-C(8)
N(3)-C(4)
2.059(16)
1.90(3)
1.14(2)
1.466(19)
Bond Angles
Si(2)-Pd(1)-Si(2′)
Si(2)-Pd(1)-C(4)
Pd(1)-Si(2)-C(7)
85.8(2)
173.7(5)
109.1(9)
Si(2)-Pd(1)-C(4′)
C(4)-Pd(1)-C(4′)
Pd(1)-Si(2)-C(8)
C(4)-N(3)-C(5)
N(3)-C(5)-C(6)
88.3(5)
97.6(6)
107.6(10)
176.7(15)
108.1(15)
108.7(14)
Pd(1)-Si(2)-C(17) 126.3(9)
Pd(1)-C(4)-N(3)
N(3)-C(5)-C(10)
179.9
107.1(14) N(3)-C(5)-C(13)
vealed that the present ring-enlargement oligomeriza-
tion was reversible (Scheme 2). Thus, the reaction
starting with the dimer 3a 2 afforded a mixture of
oligomers in a distribution almost identical with that
of the reaction with 1a . Deoligomerization of the dimer
followed by oligomerization of the resultant 1a may be
presumed. The cyclic trimer 3a 3 and tetramer 3a 4
underwent the deoligomerization and oligomerization
only to the (n - 1)-mer and (n + 1)-mer, respectively,
to a lesser extent. These findings imply that the
cyclooligomerization did not proceed by σ-bond metath-
esis between the two oligomers produced but between
the five-membered cyclic disilane 1a and the oligomers.
Concerning the intermediary palladium species, we
found that 2a reacted with 1a at room temperature to
give the six-membered cyclic bis(organosilyl)bis(tert-
butyl isocyanide)palladium(II) complex 4a (eq 4). This
Ch a r t 1
regio- and stereoisomers) and trimer 3b3 (9% yield,
many isomers), while 1c gave only dimer 3c2 under
conditions identical with those employed for 1a (eqs 2
and 3). Other cyclic disilanes 1d -g listed in Chart 1
failed to give oligomers.
very rapid, quantitative formation of 4a may also be
involved in the catalytic cycle of the oligomerization. The
structure of the corresponding adamantyl isocyanide
complex 4b was determined by a single-crystal X-ray
diffraction study (Figure 2 and Table 3). In the square-
planar complex, the angle Pd(1)-Si(2)-C(17) (>125°)
was relatively large for sp3 hybridization on the Si
atoms.
Mech a n istic In ter p r eta tion . Treatment of the
isolated oligomer 3a 2, 3a 3, or 3a 4 under the reaction
conditions employed for the oligomerization of 1a re-
The reaction of the dimer 3a 2 with 2 equiv of 2a at
room temperature was also noteworthy; it slowly gave

Synthesis of Organosilicon Macrocycles
Organometallics, Vol. 15, No. 8, 1996 2173
Ta ble 4
% yielda of linear oligomers 6n
total %
yielda
selectivityb
6n :3a n
entry no.
5
time (days)
n ) 1
n ) 2
n ) 3
n ) 4
n ) 5
n ) 6
n ) 7
1c
2c
3d
b
c
d
2
6
3
30
33
22
20
13
20
9
5
12
4
0.9
6
1.4
0.3
3
0.5
0.2
65
52
64
67:33
46:54
66:34
1.4
a
b
d
Isolated yields based on the linear disilanes 5. Ratios of the yields based on 1a . c 2.0 equiv of 1a was used. 2.5 equiv of 1a was
used.
Sch em e 3a
possible (Table 4). In the cases with 5b and 5d ,
insertion of 1a into the Si-Si bonds of the linear
disilanes occurred preferentially over the ring-enlarge-
ment oligomerization of 1a (entries 1 and 3).
Noteworthy was that insertion of 1a into 1,1,2,2-
tetramethyl-1,2-diphenyldigermane (7) also took place
to give a mixture of oligomers 8n (n ) 1-6) bearing the
dimethylphenylgermyl groups at both ends (eq 7).
a
L ) t-RNC.
the complex 4a in quantitative yield (eq 5), while the
tetramer 3a 4 failed to give 4a . Presumably, the ar-
P olym er iza tion of 1,1,2,2-Tetr a m eth yl-1,2-d isila -
cyclop en ta n e (1a ). Of particular interest is that, un-
like 2a , the (η5-cyclopentadienyl)(η3-allyl)palladium(II)
(Cp(allyl)Pd) catalyst induced polymerization of 1a to
give polymers 9 with very high molecular weights (51%,
Mn > 500 000), which were accompanied only by the
cyclic dimer 3a 2 (37%) without formation of any other
oligomers (eq 8). A separate experiment indicated that
rangement of the Si-Si bonds of the dimer was more
appropriate than that of the tetramer for intramolecular
metathesis of the Si-Si bonds in the ring,6 which
resulted in deoligomerization giving the respective (n
- 1)-mer and 4a .
A schematic illustration is presented for the ring-
enlargement oligomerization of 1a (Scheme 3). Oxida-
tive addition of 1a onto 2a affords the six-membered
bis(silyl)palladium complex 4, which may react with the
Si-Si bond of 1a or the oligomers via five-centered
activation, to give higher cyclic oligomers. Though the
cycle is reversible, the monomer 1a is completely
consumed to produce higher oligomers, since the oligo-
mers higher than the cyclic trimer hardly undergo
deoligomerization by intramolecular metathesis.
Oligom er iza tion of 1a w ith Lin ea r Disila n es.
Cross-oligomerization of 1a with any linear disilanes
according to the mechanism shown in Scheme 3 may
expand synthetic utilities of the present metathesis. We
found that linear disilanes 5 underwent insertion of 1a
to give acyclic cross-oligomerization products 6 along
with the cyclic oligomers 3a n derived from the ring-
enlargement oligomerization of 1a (eq 6). In the reaction
of hexamethyldisilane (5a ) with 1 equiv of 1a , tris-
(disilane) 6a 2 (n ) 2) was detected by mass spectroscopy,
though it could not be separated from the cyclic oligo-
mers 3a n because of their low polarity. Use of the
disilanes 5b-d , bearing a phenyl or isopropoxy group,
made isolation of the oligomeric, linear products 6n
3a 2, once isolated, remained intact under the polymer-
ization conditions employing the Cp(allyl)Pd catalyst.
A similar polymerization has also been reported by
Suzuki’s9 and Tanaka’s10 group, who carried out the
reaction of 1a in the presence of palladium-phosphine
complexes. The mechanistic discrepancy between the
polymerization and the ring-enlargement oligomeriza-
tion cannot be reasonably explained at this moment. It
may be relevant to the mechanism that a stoichiometric
reaction of Cp(allyl)Pd with 1a gave the ring-opening
product 10 (eq 9).
(9) Suzuki, M.; Obayashi, T.; Amii, H.; Saegusa, T. Polym. Prep. J pn.
1991, 40, 355.
(10) Uchimaru, Y.; Tanaka, Y.; Tanaka, M. Chem. Lett. 1995, 164.

2174 Organometallics, Vol. 15, No. 8, 1996
Suginome et al.
Ta ble 5. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for 11a
Bond Distances
Si(1)-C(18)
C(2)-C(3)
1.919(3)
1.534(6)
1.870(4)
1.923(3)
1.878(4)
1.521(6)
1.917(4)
1.282(4)
1.530(7)
1.859(6)
1.283(4)
1.428(4)
Si(1)-C(2)
1.870(4)
1.533(6)
1.927(3)
1.283(4)
1.520(6)
1.883(4)
1.919(4)
1.868(6)
1.532(8)
1.936(3)
1.430(5)
1.428(4)
C(3)-C(4)
C(4)-Si(5)
Si(5)-C(6)
C(6)-N(32)
C(8)-C(9)
C(10)-Si(11)
C(12)-Si(13)
Si(13)-C(14)
C(15)-C(16)
Si(17)-C(18)
N(31)-C(34)
N(33)-C(58)
C(6)-Si(7)
Si(7)-C(8)
C(9)-C(10)
Si(11)-C(12)
C(12)-N(33)
C(14)-C(15)
C(16)-Si(17)
C(18)-N(31)
N(32)-C(46)
Bond Angles
C(2)-Si(1)-C(18)
C(2)-C(3)-C(4)
C(4)-Si(5)-C(6)
Si(7)-C(6)-N(32)
C(6)-Si(7)-C(8)
C(8)-C(9)-C(10)
111.5(2) Si(1)-C(2)-C(3)
113.5(3) C(3)-C(4)-Si(5)
114.8(2) Si(5)-C(6)-Si(7)
128.5(2) Si(5)-C(6)-N(32)
105.9(2) Si(7)-C(8)-C(9)
114.8(3) C(9)-C(10)-Si(11)
115.1(3)
114.3(3)
124.7(2)
106.8(2)
113.7(3)
114.8(3)
C(10)-Si(11)-C(12) 105.6(2) Si(11)-C(12)-Si(13) 122.6(2)
Si(11)-C(12)-N(33) 128.0(3) Si(13)-C(12)-N(33) 109.3(2)
C(12)-Si(13)-C(14) 113.8(2) Si(13)-C(14)-C(15) 114.6(3)
C(14)-C(15)-C(16) 112.7(4) C(15)-C(16)-Si(17) 116.5(4)
C(16)-Si(17)-C(18) 106.0(2) Si(1)-C(18)-Si(17)
123.4(2)
Si(1)-C(18)-N(31)
109.6(2) Si(17)-C(18)-N(31) 127.0(2)
C(18)-N(31)-C(34) 123.7(3) C(6)-N(32)-C(46)
C(12)-N(33)-C(58) 123.4(3)
122.7(3)
Ta ble 6. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for 11b
Bond Distances
Si(1)-C(2)
C(2)-C(3)
1.870(3)
1.527(4)
1.867(3)
1.914(2)
1.875(3)
1.535(4)
1.917(2)
1.422(3)
Si(1)-C(12′)
1.918(2)
1.530(4)
1.915(2)
1.286(3)
1.535(4)
1.872(3)
1.289(3)
1.424(3)
C(3)-C(4)
C(4)-Si(5)
C(6)-Si(7)
Si(7)-C(8)
C(9)-C(10)
Si(11)-C(12)
N(21)-C(23)
Si(5)-C(6)
C(6)-N(21)
C(8)-C(9)
C(10)-Si(11)
C(12)-N(22)
N(22)-C(35)
F igu r e 3. ORTEP drawings of 11a (top) and 11b ( bottom)
(30% probability). Hydrogen atoms are omitted for clarity.
Syn th esis of Cyclic Or ga n osilicon Com p ou n d s
via In ser tion Rea ction s w ith Si-Si Lin k a ges of th e
Cyclic Oligom er s. The cyclic oligomers thus far
prepared, which contain Si-Si linkages in the ring, were
further elaborated by virtue of the high but controllable
reactivities of Si-Si toward transition-metal complex
catalysts, as demonstrated by insertion reactions of
unsaturated molecules into the Si-Si bonds. Thus, in
the presence of Pd(OAc)2 catalyst, 2,6-diisopropylphenyl
isocyanide inserted into all the Si-Si bonds of the trimer
and tetramer to give the 18-membered triimine 11a and
24-membered tetraimine 11b, respectively (eqs 10 and
11).11 Single-crystal X-ray diffraction studies of 11a and
11b showed planar triangle and lozenge shapes, respec-
tively, with each side occupied by the -Me2Si(CH2)3-
SiMe2- unit (Figure 3, Tables 5 and 6).
Bond Angles
C(2)-Si(1)-C(12′)
C(2)-C(3)-C(4)
C(4)-Si(5)-C(6)
Si(5)-C(6)-N(21)
C(6)-Si(7)-C(8)
C(8)-C(9)-C(10)
106.8 (1) Si(1)-C(2)-C(3)
112.8(2) C(3)-C(4)-Si(5)
104.4(1) Si(5)-C(6)-Si(7)
106.8(2) Si(7)-C(6)-N(21)
116.0(1) Si(7)-C(8)-C(9)
112.9(2) C(9)-C(10)-Si(11)
116.3(2)
117.4(2)
124.0(1)
129.2(2)
113.6(2)
114.3(2)
C(10)-Si(11)-C(12) 106.5(1) Si(1′)-C(12)-Si(11) 124.0(1)
Si(11)-C(12)-N(22) 128.6(2) Si(1′)-C(12)-N(22) 107.3 (2)
C(6)-N(21)-C(23)
124.0(2) C(12)-N(22)-C(35) 122.3(2)
Unexpectedly, reaction of the trimer with phenyl-
acetylene in the presence of a palladium catalyst
prepared from Pd(OAc)2 and 1,1,2,2-tetramethyl-
butyl isocyanide did not give the corresponding cyclic
trienes but resulted in formation of the the cyclic
monoene 12a and dienes 12b, in which the one or two
Si-Si linkages remained unchanged (eq 12).12 The
isolated cyclic 12b failed to undergo further insertion
of phenylacetylene.
The cyclic oligomers also underwent insertion of
oxygen atoms by oxidation of the Si-Si linkages with
trimethylamine oxide in refluxing benzene.13 The reac-
tions of the trimer and tetramer cleanly proceeded
without ring opening, affording tris(disiloxane) 13a and
(11) Ito, Y.; Suginome, M.; Matsuura, T.; Murakami, M. J . Am.
Chem. Soc. 1991, 113, 8899-8908.
(12) The expression “Ph,H” in eq 12 means that there are two
positional isomers.

Synthesis of Organosilicon Macrocycles
Organometallics, Vol. 15, No. 8, 1996 2175
Oligom er iza tion of 1,1,2,2-Tetr a m eth yl-1,2-d isila cyclo-
p en ta n e (1a ) in th e P r esen ce of 2. (a ) Gen er a l P r oce-
d u r e for th e Rea ction s in a n NMR Sa m p le Tu be.
A
mixture of 2 (5 µmol) and 1a (79 mg, 0.5 mmol) in benzene-d6
(0.6 mL) was heated at 50-80 °C under argon for the period
described in Table 1. The cooled mixture was passed through
a short column of silica gel (hexane) to remove the palladium
catalyst. Evaporation of the resulting colorless solution gave
a mixture of oligomers 3a n , which was subjected to preparative
gel permeation chromatography to separate each oligomer.
(b) P r oced u r e for th e Rea ction in a Sea led Tu be. A
mixture of 1a (158 mg, 1.0 mmol) and 2 (freshly prepared 0.5
M solution in benzene, 20 µL, 10 µmol) was heated at 50 °C
under argon in a sealed tube for 90 h. The cooled mixture
was passed through a short column of silica gel (hexane) to
remove the palladium catalyst. Evaporation of the resulting
colorless solution gave a mixture of oligomers 3a n , which was
subjected to preparative gel permeation chromatography to
separate dimer 3a 2 (4 mg, 3%), trimer 3a 3 (51 mg, 32%),
tetramer 3a 4 (53 mg, 34%), pentamer 3a 5 (22 mg, 14%),
hexamer 3a 6 (10 mg, 6%), heptamer 3a 7 (4 mg, 3%), and
octamer 3a 8 (2 mg, 1%).
tetrakis(disiloxane) 13b, respectively, in quantitative
yield (eqs 13 and 14).
1,1,2,2,6,6,7,7-O c t a m e t h y l-1,2,6,7-t e t r a s i la c y c lo -
d eca n e (3a 2): mp 71.0-72.0 °C; 1H NMR (C6D6) δ 0.14 (s, 24
H, CH3), 0.80-0.88 (m, 8 H, SiCH2), 1.52-1.70 (m, 4 H,
SiCH2CH2); 13C NMR (C6D6) δ -2.7, 20.3, 21.5; IR (KBr) 2916,
1248, 796 cm-1; MS (20 eV) m/z 316 (M+). Anal. Calcd for
C
14H36Si4: C, 53.08; H, 11.45. Found: C, 52.80; H, 11.51.
1,1,2,2,6,6,7,7,11,11,12,12-Dod eca m et h yl-1,2,6,7,11,12-
h exa sila cyclop en ta d eca n e (3a 3): mp 34.5-35.0 °C; 1H NMR
(C6D6) δ 0.17 (s, 36 H), 0.81-0.91 (m, 12 H), 1.50-1.66 (m, 6
H); 13C NMR (C6D6) δ -3.2, 21.1, 21.6; IR (neat) 2956, 1246,
Con clu sion
Oligomeric as well as polymeric organosilicon com-
pounds with regularly arranged Si-Si linkages were
synthesized from 1,1,2,2-tetramethyl-1,2-disilacyclopen-
tane in the presence of palladium catalyst. Especially,
ring-enlargement oligomerization of the cyclic disilane
gave cyclic oligomers up to the 40-membered octamer.
Bis(tert-alkyl isocyanide)palladium(0) complexes, which
give cyclic bis(organosilyl)palladium intermediates on
reaction with 1,2-disilacyclopentanes, were essential for
the ring-enlargement oligomerization and the cross-
oligomerization with linear disilanes.
800 cm-1; MS (20 eV) m/z 474 (M+). Anal. Calcd for C21H54
-
Si6: C, 53.08; H, 11.45. Found: C, 52.81; H, 11.62.
1,1,2,2,6,6,7,7,11,11,12,12,16,16,17,17-Hexa d eca m eth yl-
1,2,6,7,11,12,16,17-octa sila cycloeicosa n e (3a 4): mp 94.5-
95.5 °C; 1H NMR (C6D6) δ 0.19 (s, 48 H), 0.81-0.91 (m, 16 H),
1.51-1.67 (m, 8 H); 13C NMR (C6D6) δ -3.6, 20.6, 20.9; IR
(KBr) 2912, 1246, 828 cm-1; MS (20 eV) m/z 632 (M+). Anal.
Calcd for C28H72Si8: C, 53.08; H, 11.45. Found: C, 53.03; H,
11.53. Recrystallization from CHCl3 gave crystals suitable for
the X-ray diffraction study.
1,1,2,2,6,6,7,7,11,11,12,12,16,16,17,17,21,21,22,22-
Eicosa m eth yl-1,2,6,7,11,12,16,17,21,22-d eca sila cyclop en -
1
ta cosa n e (3a 5): H NMR (C6D6) δ 0.21 (s, 60 H), 0.83-0.92
Exp er im en ta l Section
(m, 20 H), 1.53-1.69 (m, 10 H); 13C NMR (C6D6) δ -3.5, 20.5,
20.7; IR (neat) 2956, 1246, 792 cm-1; MS (20 eV) m/z 790 (M+).
Anal. Calcd for C35H90Si10: C, 53.08; H, 11.45. Found: C,
52.80; H, 11.60.
Gen er a l Con sid er a tion s. All reactions were carried out
under a dry nitrogen or an argon atmosphere. Solvents were
purified by distillation from appropriate drying agents under
argon. 1H, 13C, and 29Si NMR spectra were recorded on a
Varian VXR-200. Proton chemical shifts (ppm) are referenced
to internal residual solvent protons: CDCl3, 7.25; C6D6, 7.20.
Carbon chemical shifts (ppm) are referenced to the carbon
signal of the deuterated solvents: CDCl3, 77.0; C6D6, 128.0.
Silicon chemical shifts are referenced to the signals of tetra-
methylsilane. Preparative gel permeation chromatography
was performed on a J AI LC-908 (J apan Analytical Industry
Co., Ltd.) equipped with J AIGEL-1H and -2H columns.
P r ep a r a tion of Bis(ison itr ile)p a lla d iu m (0) (2). The
procedure reported by Otsuka et al.14 was followed with slight
modification. To a pentane solution of (η5-cyclopentadienyl)-
(η3-allyl)palladium(II) (117 mg, 0.55 mmol) was added the
corresponding isocyanide (2.2 mmol) at -10 °C under argon.
After 10 min, removal of supernatant liquid gave 2 as an
orange solid, which was washed twice with pentane, dried in
vacuo, and used for further reaction. Complex 2 was obtained
nearly quantitatively, though the yield was not determined
for each reaction.
1,1,2,2,6,6,7,7,11,11,12,12,16,16,17,17,21,21,22,22,26,26,
27,27-Te t r a cosa m e t h yl-1,2,6,7,11,12,16,17,21,22,26,27-
d od eca sila cyclotr ia con ta n e (3a 6): mp 46.0-47.0 °C; 1H
NMR (C6D6) δ 0.22 (s, 72 H), 0.84-0.94 (m, 24 H), 1.54-1.71
(m, 12 H); 13C NMR (C6D6) δ -3.5, 20.5, 20.7; IR (neat) 2956,
1246, 790 cm-1; FABMS m/z 948 (M+). Anal. Calcd for
C
42H108Si12: C, 53.08; H, 11.45. Found: C, 53.09; H, 11.58.
1,1,2,2,6,6,7,7,11,11,12,12,16,16,17,17,21,21,22,22,26,26,
27,27,31,31,32,32-Oct a cosa m et h yl-1,2,6,7,11,12,16,17,21,
22,26,27,31,32-t e t r a d e c a s ila c y c lo p e n t a t r ia c o n t a n e
(3a 7): 1H NMR (C6D6) δ 0.22 (s, 84 H), 0.84-0.93 (m, 28 H),
1.53-1.72 (m, 14 H); 13C NMR (C6D6) δ -3.5, 20.5, 20.7; IR
(neat) 2956, 1246, 792 cm-1; FABMS m/z 1107 (M+).
1,1,2,2,6,6,7,7,11,11,12,12,16,16,17,17,21,21,22,22,26,26,
27,27,31,31,32,32,36,36,37,37-Dot r ia con t a m et h yl-1,2,6,7,
11,12,16,17,21,22,26,27,31,32,36,37-h e xa d e ca sila cyclo-
tetr a con ta n e (3a 8): 1H NMR (C6D6) δ 0.23 (s, 96 H), 0.85-
0.93 (m, 32 H), 1.54-1.72 (m, 16 H); 13C NMR (C6D6) δ -3.4,
20.5, 20.7; IR (neat) 2956, 1245, 792 cm-1; FABMS m/z 1266
[(M + 1)+].
(13) Ishikawa, M.; Hatano, T.; Hasegawa, Y.; Horio, T.; Kunai, A.;
Miyai, A.; Ishida, T.; Tsukihara, T.; Yamanaka, T.; Koike, T.; Shioya,
J . Organometallics 1992, 11, 1604-1618.
(14) Otsuka, S.; Nakamura, A.; Tatsuno, Y. J . Am. Chem. Soc. 1969,
91, 6994-6999.
Oligom er iza tion of 1,2,2-Tr im eth yl-1-p h en yl-1,2-d isila -
cyclop en ta n e (1b) in th e P r esen ce of 2a . A mixture of 1b
(220 mg, 1.0 mmol) and 2a (freshly prepared 0.25 M solution
in benzene, 40 µL, 10 µmol) was stirred at 50 °C under argon

2176 Organometallics, Vol. 15, No. 8, 1996
Suginome et al.
in a sealed tube for 87 h. The cooled mixture was passed
through a short column of silica gel (hexane/ether, 10/1) to
remove the palladium catalyst. Evaporation of the resulting
colorless solution gave a mixture of oligomers 3bn , which was
subjected to preparative gel permeation chromatography to
separate dimers 3b2 (a mixture of four isomers, 110 mg, 50%),
trimers 3b3 (a mixture of many isomers, 19 mg, 9%), and 1b
(78 mg, 35% recovered). Recrystallization of the dimers from
ethanol gave one of the four isomers, which was determined
to be (1R*,6S*)-1,2,2,6,7,7-hexamethyl-1,6-diphenyl-1,2,6,7-
tetrasilacyclodecane by the single-crystal X-ray method (see
Supporting Information).
fractions. The third fraction was analyzed by mass spectros-
copy, which revealed the existence of 6a 2 (m/z 462) along with
cyclic tetramer 3a 4 (m/z 632).
Rea ction of P en ta m eth ylp h en yld isila n e (5b) w ith 1a
in th e P r esen ce of 2a . A mixture of 5b (83 mg, 0.4 mmol),
1a (158 mg, 1.0 mmol), and 2a (freshly prepared 0.1 M solution
in benzene, 100 µL, 10 µmol) in benzene (0.4 mL) was heated
in a sealed tube at 50 °C for 90 h. Preparative TLC (hexane)
afforded mixtures of 6bn and cyclic oligomers 3a n (n ) 2-6,
29 mg, 0.18 mmol of the -Me2Si(CH2)3SiMe2- unit). The
mixture of 6bn was subjected to preparative gel permeation
chromatography to give 6b1 (30 mg, 20%), 6b2 (28 mg, 13%),
6b3 (22 mg, 8%), 6b4 (16 mg, 5%), 6b5 (8 mg, 2%), 6b6 (4 mg,
1%), and 6b7 (3 mg, 0.6%). Elemental analyses were carried
out for 6b1, 6b2, and 6b3.
3b2: 1H NMR for the (1R*,6S*) isomer (CDCl3) δ -0.02 (s,
6 H, SiCH3CH3), 0.10 (s, 6 H, SiCH3CH3), 0.35 (s, 6 H,
PhSiCH3), 0.74-1.26 (m, 8 H, SiCH2), 1.64-1.80 (m, 4 H,
SiCH2CH2), 7.30-7.36 (m, 6 H, Ar H), 7.40-7.48 (m, 4 H, Ar
H); MS (23 eV) m/z 440 (M+). Elemental analysis was carried
out for the mixture of isomers. Anal. Calcd for C24H40Si4: C,
65.38; H, 9.14. Found: C, 65.44; H, 9.37.
6b1: 1H NMR (CDCl3) δ -0.01 (s, 6 H), 0.03 (s, 15 H), 0.34
(s, 6 H), 0.56-0.70 (m, 4 H), 1.24-1.40 (m, 2 H), 7.30-7.36
(m, 3 H), 7.42-7.48 (m, 2 H); 13C NMR (CDCl3) δ -4.3, -4.0,
-3.6, -2.0, 19.8, 127.7, 128.2, 133.7, 139.8; MS (23 eV) m/z
3b3: MS (23 eV) m/z 660 (M+). Anal. Calcd for C36H60Si6:
C, 65.38; H, 9.14. Found: C, 65.44; H, 9.32.
366 (M+
). Anal. Calcd for C18H38Si4: C, 58.94; H, 10.44.
Found: C, 59.00; H, 10.35.
6b2: 1H NMR (CDCl3) δ -0.01 (s, 6 H), 0.01 (s, 6 H), 0.02
(s, 6 H), 0.04 (s, 6 H), 0.05 (s, 9 H), 0.34 (s, 6 H), 0.56-0.70
(m, 8 H), 1.22-1.44 (m, 4 H), 7.30-7.36 (m, 3 H), 7.42-7.48
(m, 2 H); 13C NMR (CDCl3) δ -4.2, -4.0, -3.8, -3.6, -2.0,
19.78, 19.81, 19.9, 20.1, 20.2, 127.7, 128.2, 133.7, 139.8; MS
(23 eV) m/z 524 (M+). Anal. Calcd for C25H56Si6: C, 57.17; H,
10.75. Found: C, 57.35; H, 10.97.
6b3: 1H NMR (CDCl3) δ -0.01 (s, 6 H), 0.00 (s, 6 H), 0.017
(s, 6 H), 0.022 (s, 12 H), 0.03 (s, 6 H), 0.05 (s, 9 H), 0.34 (s, 6
H), 0.56-0.70 (m, 12 H), 1.24-1.46 (m, 6 H), 7.30-7.36 (m, 3
H), 7.42-7.48 (m, 2 H); 13C NMR (CDCl3) δ -4.2, -4.0, -3.8,
-3.6, -2.0, 19.79, 19.85, 19.91, 20.1, 20.2, 127.7, 128.2, 133.7,
139.8; MS (23 eV) m/z 682 (M+). Anal. Calcd for C32H74Si8:
C, 56.22; H, 10.91. Found: C, 56.12; H, 11.11.
6b4: 1H NMR (CDCl3) δ -0.01 (s, 6 H), 0.01 (s, 6 H), 0.02
(s, 30 H), 0.03 (s, 6 H), 0.05 (s, 9 H), 0.34 (s, 6 H), 0.56-0.70
(m, 16 H), 1.22-1.48 (m, 8 H), 7.30-7.36 (m, 3 H), 7.42-7.48
(m, 2 H); 13C NMR (CDCl3) δ -4.2, -4.0, -3.8, -3.6, -2.0,
19.76, 19.85, 19.90, 20.1, 20.2, 127.7, 128.2, 133.7, 139.8.
6b 5: 1H NMR (CDCl3) δ -0.02 (s, 6 H), 0.00 (s, 6 H), 0.02
(s, 42 H), 0.03 (s, 6 H), 0.05 (s, 9 H), 0.33 (s, 6 H), 0.56-0.70
(m, 20 H), 1.22-1.46 (m, 10 H), 7.30-7.36 (m, 3 H), 7.42-7.48
(m, 2 H); 13C NMR (CDCl3) δ -4.2, -4.0, -3.8, -3.6, -2.0,
19.75, 19.85, 19.89, 20.1, 20.2, 127.7, 128.2, 133.7, 139.8.
6b 6: 1H NMR (CDCl3) δ -0.02 (s, 6 H), 0.00 (s, 6 H), 0.02
(s, 60 H), 0.04 (s, 9 H), 0.33 (s, 6 H), 0.56-0.70 (m, 24 H), 1.24-
1.46 (m, 12 H), 7.30-7.36 (m, 3 H), 7.42-7.48 (m, 2 H); 13C
NMR (CDCl3) δ -4.2, -4.0, -3.8, -3.6, -2.0, 19.8, 19.9, 20.2,
127.7, 128.2, 133.7, 139.8.
6b7: 1H NMR (CDCl3) δ -0.02 (s, 6 H), 0.00 (s, 6 H), 0.02
(s, 72 H), 0.04 (s, 9 H), 0.33 (s, 6 H), 0.56-0.70 (m, 28 H), 1.24-
1.48 (m, 14 H), 7.30-7.36 (m, 3 H), 7.42-7.48 (m, 2 H).
Rea ction of 1,2,2,2-Tetr a m eth yl-1,1-d ip h en yld isila n e
(5c) w ith 1a in th e P r esen ce of 2a . By a procedure similar
to that used for the synthesis of 6b, reaction of 5c (135 mg,
0.50 mmol) with 1a (158 mg, 1.0 mmol) in the presence of 2a
(10 µmol) was carried out to give 6c1 (71 mg, 33%), 6c2 (39
mg, 13%), 6c3 (18 mg, 5.0%), 6c4 (4.2 mg, 0.9%), and 6c5 (1.4
mg, 0.3%).
Oligom er iza tion of 1,1-Dieth yl-2,2-d im eth yl-1,2-d isila -
cyclop en ta n e (1c) in th e P r esen ce of 2a . A mixture of 1c
(186 mg, 1.0 mmol) and 2a (freshly prepared 0.25 M solution
in benzene, 40 µL, 10 µmol) was stirred at 50 °C under argon
in a sealed tube for 8 days. The cooled mixture was passed
through a short column of silica gel (hexane) to remove the
palladium catalyst. After evaporation of the resulting colorless
solution, the residue was subjected to preparative gel perme-
ation chromatography to furnish dimer 3c2 (a mixture of two
isomers, 23 mg, 12%). 3c2: 1H NMR (C6D6) δ 0.15 (s, 12 H for
the minor isomer), 0.20 (s, 12 H for the major isomer), 0.60-
0.78 (m, 8 H for both isomers), 0.82-0.94 (m, 8 H for both
isomers), 1.05 (t, J ) 7.4 Hz, 12 H for the major isomer), 1.06
(t, J ) 7.7 Hz, 12 H for the minor isomer), 1.56-1.74 (m, 4 H
for both isomers); MS (23 eV) m/z 372 (M+). Anal. Calcd for
C
18H44Si4: C, 57.98; H, 11.89. Found: C, 57.80; H, 12.10.
Gen er a l P r oced u r e for th e Rea ction s of Isola ted
Oligom er s 3a 2, 3a 3, a n d 3a 4. The oligomer 3a n (79 mg, 0.50
mmol of the -Me2Si(CH2)3SiMe2- unit), 2a (freshly prepared
0.1 M solution in benzene, 50 µL, 5 µmol), and benzene (0.2
mL) was stirred at 50 °C under argon for 40 h. The cooled
mixture was passed through a short column of silica gel
(hexane) to remove the palladium catalyst. Evaporation of the
resulting colorless solution gave a mixture of oligomers, which
was subjected to preparative gel permeation chromatography
to separate into each oligomer.
P r ep a r a tion of Bis(or ga n osilyl)p a lla d iu m -Isocya n id e
Com p lex 4b. To a benzene (1 mL) solution of 2b (0.2 mmol)
was added 1a (32 mg, 0.2 mmol) at room temperature under
an argon atmosphere. After 30 min, evaporation of the solvent
followed by recrystallization from benzene/pentane (1/4) af-
forded 4b (114 mg, 97%) as a crystalline solid. Recrystalliza-
tion from benzene/pentane (4/1) gave crystals suitable for the
X-ray diffraction study. 4b: 1H NMR (C6D6) δ 0.79 (s, 12 H),
1.16-1.25 (m, 4 H), 1.26 (br, 12 H), 1.66 (br, 6 H), 1.80 (br, 12
H), 2.28-2.42 (m, 2 H); 13C NMR (C6D6) δ 7.1, 22.3, 22.8, 28.8,
35.3, 43.0, 56.1, 146.7; 29Si NMR (C6D6) δ -0.3; IR (benzene)
2146 cm-1. Anal. Calcd for C29H48N2PdSi2: C, 59.31; H, 8.24;
N, 4.77. Found: C, 59.15; H, 8.37; N, 4.74.
Stoich iom etr ic Rea ction of Cyclic Dim er 3a 2 w ith 2a .
To a benzene-d6 (0.3 mL) solution of 2a (0.05 mmol) in an NMR
sample tube was added a benzene-d6 (0.3 mL) solution of 3a 2
(7.9 mg, 0.025 mmol) at room temperature under an argon
atmosphere. After 5 h at room temperature, 1H NMR showed
quantitative formation of 4a .
6c1: 1H NMR (C6D6) δ 0.05 (s, 6 H), 0.11 (s, 9 H), 0.22 (s, 6
H), 0.65 (s, 3 H), 0.58-0.71 (m, 2 H), 0.78-0.94 (m, 2 H), 1.36-
1.52 (m, 2 H), 7.15-7.30 (m, 6 H), 7.55-7.65 (m, 4 H); 13C NMR
(CDCl3) δ -4.5, -4.3, -3.5, -2.0, 19.7, 19.8, 20.1, 127.8, 128.6,
134.8, 137.6; MS (23 eV) m/z 428 (M+). Anal. Calcd for C23H40
-
Si4: C, 64.41; H, 9.40. Found: C, 64.04; H, 9.39.
Rea ction of Hexa m eth yld isila n e (5a ) w ith 1a in th e
P r esen ce of 2a . A mixture of 5a (37 mg, 0.25 mmol), 1a (40
mg, 0.25 mmol), and 2a (freshly prepared 0.1 M solution in
benzene, 50 µL, 5 µmol) in benzene (0.4 mL) was heated at 50
°C for 20 h. The cooled mixture was passed through a short
column of silica gel (hexane). After evaporation of the solvent,
the residue was subjected to preparative GPC to give five
6c2: 1H NMR (C6D6) δ 0.12 (s, 6 H), 0.14 (s, 6 H), 0.15 (s, 6
H), 0.16 (s, 9 H), 0.24 (s, 6 H), 0.66 (s, 3 H), 0.68-0.92 (m, 8
H), 1.42-1.64 (m, 4 H), 7.15-7.32 (m, 6 H), 7.55-7.65 (m, 4
H); 13C NMR (CDCl3) δ -4.5, -4.2, -3.91, -3.86, -3.5, -2.0,
19.7, 19.9, 20.1, 127.8, 128.7, 134.8, 137.6. Anal. Calcd for
C
30H58Si6: C, 61.35; H, 9.95. Found: C, 61.31; H, 10.11.

Synthesis of Organosilicon Macrocycles
Organometallics, Vol. 15, No. 8, 1996 2177
6c3: 1H NMR (C6D6) δ 0.12 (s, 6 H), 0.15 (s, 6 H), 0.16 (s, 15
H), 0.20 (s, 12 H), 0.24 (s, 6 H), 0.66 (s, 3 H), 0.76-0.92 (m, 12
H), 1.46-1.68 (m, 6 H), 7.15-7.30 (m, 6 H), 7.55-7.65 (m, 4
H); 13C NMR (CDCl3) δ -4.5, -4.2, -3.9, -3.8, -3.5, -2.0,
19.7, 19.8, 19.9, 20.1, 20.2, 127.8, 128.6, 134.8, 137.6. Anal.
Calcd for C37H76Si8: C, 59.60; H, 10.27. Found: C, 59.72; H,
10.49.
SiCH2CH2), 7.18-7.35 (m, 6 H, Ar H), 7.43-7.59 (m, 4 H, Ar
H); 13C NMR (CDCl3) δ -4.1, -3.4, 19.6, 20.2, 127.6, 127.9,
133.5, 142.5; MS (23 eV) m/z 518 (M+). Anal. Calcd for
C
23H40Ge2Si2: C, 53.34; H, 7.78. Found: C, 53.22; H, 7.93.
82: 1H NMR (C6D6) δ 0.13 (s, 12 H), 0.18 (s, 12 H), 0.51 (s,
12 H), 0.66-0.81 (m, 8 H), 1.35-1.59 (m, 4 H), 7.19-7.36 (m,
6 H), 7.47-7.58 (m, 4 H); 13C NMR (CDCl3) δ -4.1, -3.9, -3.3,
19.7, 20.0, 20.4, 127.6, 127.9, 133.5, 142.5; MS (23 eV) m/z 676
(M+). Anal. Calcd for C30H58Ge2Si4: C, 53.28; H, 8.64.
Found: C, 53.00; H, 8.91.
83: 1H NMR (C6D6) δ 0.16 (s, 12 H), 0.18 (s, 24 H), 0.52 (s,
12 H), 0.70-0.88 (m, 12 H), 1.41-1.67 (m, 6 H), 7.21-7.34
(m, 6 H), 7.50-7.59 (m, 4 H); 13C NMR (CDCl3) δ -4.1, -3.9,
-3.3, 19.7, 19.8, 20.0, 20.1, 20.4, 127.6, 127.9, 133.5, 142.6;
MS (23 eV) m/z 834 (M+). Anal. Calcd for C37H76Ge2Si6: C,
53.24; H, 9.18. Found: C, 53.11; H, 9.43.
6c4: 1H NMR (C6D6) δ 0.13 (s, 6 H), 0.15 (s, 6 H), 0.17 (s, 15
H), 0.210 (s, 6 H), 0.213 (s, 18 H), 0.25 (s, 6 H), 0.67 (s, 3 H),
0.78-0.94 (m, 16 H), 1.48-1.71 (m, 8 H), 7.15-7.30 (m, 6 H),
7.55-7.65 (m, 4 H).
6c5: 1H NMR (C6D6) δ 0.13 (s, 6 H), 0.15 (s, 6 H), 0.17 (s, 12
H), 0.21 (s, 9 H), 0.22 (br s, 30 H), 0.25 (s, 6 H), 0.67 (s, 3 H),
0.79-0.93 (m, 20 H), 1.47-1.68 (m, 10 H), 7.15-7.31 (m, 6
H), 7.53-7.65 (m, 4 H).
Rea ction of 1-Isop r op oxy-1,2,2,2-tetr a m eth yl-1-p h en -
yld isila n e (5d ) w ith 1a in th e P r esen ce of 2a . By a
procedure similar to that used for the synthesis of 6b, reaction
of 5d (126 mg, 0.50 mmol) with 1a (228 mg, 1.3 mmol) in the
presence of 2a (13 µmol) was carried out to give 6d 1 (18 mg,
22%), 6d 2 (33 mg, 20%), 6d 3 (30 mg, 12%), 6d 4 (20 mg, 6%),
6d 5 (11 mg, 3%), and 6d 6 (6.6 mg, 1.4%).
84: 1H NMR (C6D6) δ 0.16 (s, 12 H), 0.18 (s, 24 H), 0.21 (s,
12 H), 0.52 (s, 12 H), 0.70-0.91 (m, 16 H), 1.41-1.69 (m, 8
H), 7.15-7.32 (m, 6 H), 7.46-7.54 (m, 4 H).
85: 1H NMR (C6D6) δ 0.17 (s, 12 H), 0.19 (s, 24 H), 0.22 (s,
24 H), 0.52 (s, 12 H), 0.72-0.93 (m, 20 H), 1.44-1.75 (m, 10
H), 7.19-7.35 (m, 6 H), 7.48-7.56 (m, 4 H).
6d 1: 1H NMR (C6D6) δ 0.11 (s, 6 H), 0.14 (s, 9 H), 0.21 (s, 6
H), 0.57 (s, 3 H), 0.67-0.88 (m, 4 H), 1.15 (d, J ) 6.1 Hz, 6 H),
1.42-1.62 (m, 2 H), 3.96 (septet, J ) 6.1 Hz, 1 H), 7.18-7.33
(m, 3 H), 7.65-7.72 (m, 2 H); 13C NMR (CDCl3) δ -4.3, -3.8,
-2.0, -1.2, 19.7, 19.8, 19.9, 25.9, 26.0, 66.2, 127.7, 128.9, 133.6,
86: 1H NMR (C6D6) δ 0.17 (s, 12 H), 0.19 (s, 24 H), 0.22 (br
s, 36 H), 0.53 (s, 12 H), 0.78-0.93 (m, 24 H), 1.46-1.72 (m, 12
H), 7.16-7.33 (m, 6 H), 7.47-7.58 (m, 4 H).
P olym er iza tion of 1a in th e P r esen ce of Cp (π-a llyl)-
P d . A mixture of 1a (158 mg, 1.0 mmol) and (η5-cyclopenta-
dienyl)(η3-allyl)palladium(II) (2 mg, 10 µmol) was stirred at
50 °C under argon for 40 h. The cooled gummy mixture was
dissolved into CHCl3 and passed through a filter to remove
the palladium catalyst. Evaporation of the resulting colorless
solution and separation by preparative gel permeation chro-
matography gave the cyclic dimer 3 (n ) 2, 51 mg, 37%) and
polymers 9 (80 mg, 51%). GPC analysis of the polymer showed
molecular weights >500 000 (polystyrene standard). Spectral
data for the polymers: 1H NMR (C6D6) δ 0.25 (s, 12n H), 0.85-
0.96 (m, 4n H), 1.56-1.74 (m, 2n H); 13C NMR (C6D6) δ -3.6,
139.5. Anal. Calcd for
C20H42OSi4: C, 58.46; H, 10.30.
Found: C, 58.59; H, 10.57.
6d 2: 1H NMR (C6D6) δ 0.14 (s, 6 H), 0.16 (s, 9 H), 0.17 (s, 6
H), 0.18 (s, 6 H), 0.23 (s, 6 H), 0.58 (s, 3 H), 0.72-0.92 (m, 8
H), 1.15 (d, J ) 6.1 Hz, 6 H), 1.46-1.66 (m, 4 H), 3.98 (septet,
J ) 6.1 Hz, 1 H), 7.20-7.35 (m, 3 H), 7.66-7.73 (m, 2 H); 13
C
NMR (CDCl3) δ -4.2, -3.9, -3.84, -3.75, -2.0, -1.2, 19.7,
19.9, 20.1, 20.2, 25.9, 66.2, 127.7, 128.9, 133.6, 139.5. Anal.
Calcd for C27H60OSi6: C, 56.92; H, 10.62. Found: C, 56.66;
H, 10.43.
6d 3: 1H NMR (C6D6) δ 0.15 (s, 6 H), 0.16 (s, 9 H), 0.17 (s, 6
H), 0.19 (s, 6 H), 0.198 (s, 6 H), 0.200 (s, 6 H), 0.23 (s, 6 H),
0.58 (s, 3 H), 0.73-0.92 (m, 12 H), 1.16 (d, J ) 6.1 Hz, 6 H),
1.46-1.69 (m, 6 H), 3.94 (septet, J ) 6.1 Hz, 1 H), 7.15-7.35
(m, 3 H), 7.65-7.74 (m, 2 H); 13C NMR (CDCl3) δ -4.2, -3.82,
-3.75, -2.0, -1.2, 19.6, 19.8, 19.9, 20.1, 20.2, 25.90, 25.94,
66.2, 127.7, 128.9, 133.6, 139.5. Anal. Calcd for C34H78OSi8:
C, 56.12; H, 10.80. Found: C, 56.25; H, 10.93.
6d 4: 1H NMR (C6D6) δ 0.15 (s, 6 H), 0.17 (s, 6 H), 0.18 (s, 6
H), 0.19 (s, 6 H), 0.20 (s, 6 H), 0.21 (br s, 21 H), 0.23 (s, 6 H),
0.58 (s, 3 H), 0.76-0.92 (m, 16 H), 1.16 (d, J ) 6.1 Hz, 6 H),
1.46-1.70 (m, 8 H), 3.90 (septet, J ) 6.1 Hz, 1 H), 7.15-7.34
(m, 3 H), 7.65-7.72 (m, 2 H); 13C NMR (CDCl3) δ -4.2, -3.9,
-3.8, -2.0, -1.3, 19.6, 19.8, 19.9, 20.1, 20.2, 25.89, 25.94, 66.2,
127.7, 128.9, 133.6, 139.5. Anal. Calcd for C41H96OSi10: C,
55.58; H, 10.92. Found: C, 55.61; H, 11.19.
20.5, 20.7; IR (neat) 2960, 1246, 788 cm-1
.
Stoich iom etr ic Rea ction of 1a w ith Cp (π-a llyl)P d . A
mixture of 1a (32 mg, 0.2 mmol) and (η5-cyclopentadienyl)(η3-
allyl)palladium(II) (42 mg, 0.2 mmol) was stirred at room
temperature under argon for 4 h. The mixture was passed
through a short column of silica gel (hexane). Evaporation of
the resulting colorless solution gave crude material, which was
further purified by preparative HPLC to give pure 10 (30 mg,
57%). 10: 1H NMR (C6D6) for major positional isomer, i.e.,
1-(2,4-cyclopentadienyl)-1,1,2,2-tetramethyl-2-(2-propenyl)-
disilane; δ -0.09 (s, 6 H), 0.01 (s, 6 H), 0.50-0.64 (m, 4 H),
1.28-1.45 (m, 2 H), 1.50 (dt, J ) 8.2, 1.2 Hz, 2 H), 3.34 (br, 1
H), 4.89-5.02 (m, 2 H), 5.70-5.94 (m, 1 H), 6.46-6.74 (br, 4
H); 13C NMR (C6D6) for the major positional isomer δ -3.9,
-3.6, 18.9, 19.6, 20.2, 23.5, 51.4, 113.1, 130.6, 133.3, 135.3;
HRMS calcd for C15H28Si2 264.1729, found 264.1744.
6d 5: 1H NMR (C6D6) δ 0.15 (s, 6 H), 0.17 (s, 6 H), 0.18 (s, 6
H), 0.20 (s, 6 H), 0.21 (s, 6 H), 0.22 (s, 33 H), 0.58 (s, 3 H),
0.72-0.93 (m, 20 H), 1.16 (d, J ) 6.1 Hz, 6 H), 1.45-1.71 (m,
10 H), 3.97 (septet, J ) 6.1 Hz, 1 H), 7.15-7.36 (m, 3 H), 7.65-
7.74 (m, 2 H); 13C NMR (CDCl3) δ -4.2, -3.8, -2.0, -1.2, 19.6,
19.8, 20.2, 25.9, 66.2, 127.7, 128.9, 133.6, 139.5.
6d 6: 1H NMR (C6D6) δ 0.16 (s, 6 H), 0.17 (s, 6 H), 0.18 (s, 6
H), 0.19 (s, 6 H), 0.20 (s, 6 H), 0.21 (br s, 45 H), 0.23 (s, 6 H),
0.58 (s, 3 H), 0.74-0.94 (m, 24 H), 1.16 (d, J ) 6.1 Hz, 6 H),
1.47-1.72 (m, 12 H), 3.96 (septet, J ) 6.1 Hz, 1 H), 7.15-7.32
(m, 3 H), 7.66-7.73 (m, 2 H).
Syn th esis of Cyclic Tr iim in e 11a . A mixture of the
trimer 3a 3 (79 mg, 0.17 mmol), 2,6-diisopropylphenyl iso-
cyanide (140 mg, 0.75 mmol), and Pd(OAc)2 (2.2 mg, 0.01
mmol) in toluene (0.5 mL) was heated under reflux for 26 h.
The cooled mixture was passed through a short column of
Et3N-pretreated Florisil (hexane) to remove the palladium
catalyst. Crystallization from dry EtOH afforded triimine 11a
(103 mg, 60%) as yellow crystals. Recrystallization from
benzene/EtOH (1/5) gave crystals suitable for the X-ray
1
diffraction study. 11a : mp 156.0-157.0 °C (sealed tube); H
NMR (toluene-d8, 100 °C) δ 0.44 (s, 36 H, SiCH3), 1.28-1.56
(m, 12H, SiCH2), 1.50 (d, J ) 6.6 Hz, 36 H, CHCH3), 1.74-
2.00 (m, 6 H, SiCH2CH2), 3.08-3.30 (m, 6 H, CHCH3), 7.24-
R ea ct ion
of
1,1,2,2-Tet r a m et h yl-1,2-d ip h en yld i-
ger m a n e (7) w ith 1a in th e P r esen ce of 2a . By a procedure
similar to that used for the synthesis of 6b, reaction of 7 (180
mg, 0.50 mmol) with 1a (158 mg, 1.0 mmol) in the presence of
2a (10 µmol) was carried out to give 81 (67 mg, 26%), 82 (63
mg, 19%), 83 (50 mg, 11%), 84 (35 mg, 7.2%), 85 (10 mg, 1.7%),
and 86 (5.1 mg, 0.8%).
7.46 (m, 9 H, Ar H); IR (KBr) 3068, 2968, 1544, 1252, 830 cm-1
;
FABMS m/z 1036 (M+). Anal. Calcd for C60H105N3Si6: C,
69.49; H, 10.21; N, 4.05. Found: C, 69.39; H, 10.48; N, 3.86.
Syn th esis of Cyclic Tetr a im in e 11b. A mixture of the
tetramer 3a 4 (63 mg, 0.1 mmol), 2,6-diisopropylphenyl iso-
cyanide (112 mg, 0.6 mmol), and Pd(OAc)2 (4.5 mg, 0.02 mmol)
in toluene (0.5 mL) was heated under reflux for 36 h. The
81: 1H NMR (C6D6) δ 0.12 (s, 12 H, SiCH3), 0.48 (s, 12 H,
GeCH3), 0.64-0.75 (m, 4 H, SiCH2), 1.27-1.46 (m, 2 H,

2178 Organometallics, Vol. 15, No. 8, 1996
Ta ble 7. Su m m a r y of Cr ysta llogr a p h ic Da ta
Suginome et al.
3a 4
4b
11a
11b
formula
fw
C28H72Si8
633.6
C29H48N2PdSi2
587.3
C60H105N3Si6
1037.0
C80H140N4Si8
1380.0
cryst syst
space group
a, Å
b, Å
c, Å
monoclinic
C2/c (No. 15)
21.700(8)
13.598(6)
15.336(9)
107.88(4)
4307(3)
4
monoclinic
C2/c (No. 15)
22.761(7)
11.268(3)
14.379(6)
121.26(2)
3152(2)
4
orthorhombic
Pna21 (No. 33)
18.862(4)
26.369(4)
13.889(3)
monoclinic
P21/a (No. 14)
18.603(4)
13.669(3)
18.345(3)
94.28(2)
4652(2)
2
â, deg
cell vol, Å3
Z
6908(2)
4
1.00
2280
F(calcd), g cm-3
F(000)
0.98
1408
1.24
1240
0.99
1520
cryst size, mm
0.50 × 0.50 × 0.30
0.60 × 0.30 × 0.35
0.50 × 0.45 × 0.40
0.25 × 0.35 × 0.40
µ, cm-1
2.27
57.239
12.94
Cu KR
130
12.81
radiation
2θmax, deg
no. of rflns measd
no. of indep rflns
no. of rflns used
no. of variables
R, Rw
Mo KR
50
5432
4953
3417
Cu KR
130
2999
2641
2380
182
0.081, 0.108
Cu KR
130
8584
7768
7046
629
0.068, 0.047
6477
5902
5730
940
277
0.065, 0.071
0.040, 0.039
cooled mixture was passed through a short column of Et3N-
pretreated Florisil (hexane) to remove the palladium catalyst.
Crystallization from dry EtOH afforded tetraimine 11b (92 mg,
67%) as yellow crystals. Recrystallization from benzene/EtOH
(1/5) gave crystals suitable for the X-ray diffraction study.
Syn th esis of Com p ou n d 13b. By a procedure similar to
that used for the synthesis of 13a , reaction of the tetramer
3a 4 (79 mg, 0.125 mmol) with trimethylamine oxide (45 mg,
0.60 mmol) was carried out to give tetrakis(disiloxane) 13b
(87 mg, quantitative). 13b: 1H NMR (C6D6) δ 0.21 (s, 48 H),
0.85-0.95 (m, 16 H), 1.56-1.75 (m, 8 H); 13C NMR (C6D6) δ
0.77, 17.8, 23.3; IR (KBr) 2968, 1414, 1256, 1064 cm-1; MS
m/z 696 (M+). Anal. Calcd for C28H72O4Si8: C, 48.21; H, 10.40.
Found: C, 48.50; H, 10.66.
1
11b: mp 150.0-151.0 °C (sealed tube); H NMR (toluene-d8,
90 °C) δ 0.49 (s, 48 H), 1.20-1.45 (m, 16H), 1.51 (br s, 48 H),
1.76-1.98 (m, 8 H), 3.10-3.30 (m, 8 H), 7.25-7.46 (m, 12 H);
IR (KBr) 3072, 2972, 1540, 1258, 1250, 1138, 928 cm-1
;
FABMS m/z 1381 (M+). Anal. Calcd for C80H140N4Si8: C,
69.49; H, 10.21; N, 4.05. Found: C, 69.48; H, 10.44; N, 3.91.
P a lla d iu m -Ca ta lyzed Rea ction of th e Cyclic Tr im er
w ith P h en yla cetylen e. To a mixture of Pd(OAc)2 (2.2 mg,
0.01 mmol) and 1,1,3,3-tetramethylbutyl isocyanide (21 mg,
0.15 mmol) was added trimer 3a 3 (79 mg, 0.17 mmol) and
phenylacetylene (77 mg, 0.75 mmol) under a nitrogen atmo-
sphere. The mixture was stirred under reflux for 26 h, cooled
to room temperature, and then subjected to preparative TLC
(hexane) to furnish 12b (23 mg, 20%) and another fraction
containing 12a . The crude fraction was further purified by
preparative GPC to give pure 12a (40 mg, 42%). 12a : 1H NMR
(CDCl3) δ 0.01 (s, 12 H), 0.04 (s, 6 H), 0.05 (s, 6 H), 0.10 (s, 6
H), 0.18 (s, 6 H), 0.60-0.86 (m, 12 H), 1.24-1.52 (m, 6 H),
6.42 (s, 1 H), 6.98-7.04 (m, 2 H), 7.14-7.30 (m, 3 H); 13C NMR
(CDCl3) δ -3.9, -3.8, -3.7, -0.5, 19.2, 19.3, 20.5, 20.6, 20.7,
21.1, 21.2, 22.1, 125.5, 126.3, 127.7, 148.7, 151.1, 164.1; IR
X-r a y Diffr a ction Stu d ies. Single crystals of the com-
pounds were mounted on glass fibers (for 3a 4, 11a , and 11b)
or sealed in a glass capillary (for 4b). Intensity data collections
were carried out with a Mac Science MXC3 diffractometer
using graphite-monochromated Cu KR (λ ) 1.541 78 Å) or Mo
KR (λ ) 0.710 69 Å) radiation at 293 K. Intensity data were
collected using ω/2θ scans and corrected for Lorentz-polariza-
tion and for absorption by an analytical function. Details of
crystal and data collection parameters are shown in Table 7.
Structure solutions and refinements were carried out with the
program package CrystanG (Mac Science). All non-hydrogen
atoms were refined anisotropically by full-matrix least squares.
For compound 4b, C(18) was split into two sites, i.e., both sides
of the square plane around the Pd atom, and was refined with
an occupation factor of 0.5. For compounds 3a 4, 11a , and 11b,
all hydrogen atoms except for those on C(21) and C(53) of 11a
and C(30) and C(31) of 11b were located on a difference
electron density map and refined with isotropic thermal
parameters calculated from those of the bonded atoms. For
compound 4b, all hydrogen atoms except for those on C(18)
were included in the refinement at the calculated positions
(0.96 Å) with isotropic thermal parameters.
(neat) 3064, 2960, 1490, 1248, 832 cm-1
. Anal. Calcd for
C
29H60Si6: C, 60.34; H, 10.48. Found: C, 60.10; H, 10.55. 12b
(mixture of three isomers): 1H NMR (CDCl3) δ 0.01-0.21
(many singlets, 36 H), 0.64-0.90 (m, 12 H), 1.26-1.56 (m, 6
H), 6.41-6.44 (three singlets, 2H), 6.96-7.04 (m, 4 H), 7.14
-7.30 (m, 6 H); IR (neat) 3080, 2960, 1490, 1250, 832 cm-1
.
Anal. Calcd for C37H66Si6: C, 65.41; H, 9.79. Found: C, 65.21;
H, 10.06.
Su p p or tin g In for m a tion Ava ila ble: Tables of final
atomic coordinates, thermal parameters, bond distances, and
bond angles for compounds 3a 4, 4b, 11a , and 11b, and a figure
giving the crystal structure of (1R*,6S*)-3b2 (17 pages). This
material is contained in many libraries on microfiche, im-
mediately follows this article in the microfilm version of the
journal, can be ordered from the ACS, and can be downloaded
from the Internet; see any current masthead page for ordering
information and Intermet access instructions.
Syn th esis of Com p ou n d 13a . A mixture of the trimer 3a 3
(79 mg, 0.17 mmol) and trimethylamine oxide (38 mg, 0.5
mmol) in benzene (3 mL) was heated under reflux for 46 h.
The reaction mixture was cooled to room temperature and then
subjected to column chromatography on silica gel (hexane) to
furnish tris(disiloxane) 13a (87 mg, quantitative). 13a : 1H
NMR (C6D6) δ 0.20 (s, 36 H), 0.82-0.92 (m, 12 H), 1.58-1.78
(m, 6 H); 13C NMR (C6D6) δ 0.76, 17.7, 23.2; IR (KBr) 2964,
1412, 1254, 1070 cm-1; MS m/z 522 (M+). Anal. Calcd for
C
21H54O3Si6: C, 48.21; H, 10.40. Found: C, 48.14; H, 10.60.
OM950883G