Reactions of [o-(Fluorodimethylsilyl)phenyl]lithium with GeCl2 and SnCl2: Preparation of polyfunctionalized four-membered and five-membered cyclic linkages of heavier group 14 elements

Article abstract of DOI:10.1021/om900694u

Reactions of [o-(fluorodimethylsilyl)phenyl]lithium (1) with GeCl ₂ and SnCl₂ produce benzosilagermacyclobutene 2 and benzosiladistannacyclopentene 3, respectively, both of which have o-(fluorodimethylsilyl)phenyl groups on the germa

Full text of DOI:10.1021/om900694u

Organometallics 2009, 28, 6347–6351 6347
DOI: 10.1021/om900694u
Reactions of [o-(Fluorodimethylsilyl)phenyl]lithium with GeCl2 and
SnCl2: Preparation of Polyfunctionalized Four-Membered and
Five-Membered Cyclic Linkages of Heavier Group 14 Elements
Atsushi Kawachi,* Koji Machida, and Yohsuke Yamamoto
Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama,
Higashi-Hiroshima 739-8526, Japan
Received August 5, 2009
Reactions of [o-(fluorodimethylsilyl)phenyl]lithium (1) with GeCl2 and SnCl2 produce benzosila-
germacyclobutene 2 and benzosiladistannacyclopentene 3, respectively, both of which have
o-(fluorodimethylsilyl)phenyl groups on the germanium and tin atoms. The molecular structures
of 2 and 3 were determined by X-ray crystallographic analysis, which reveals the structural features of
the functionalized four- and five-membered cyclic linkages of the heavior group 14 elements.
Introduction
initially introduced into the framework, and then, the functional
group on the silicon is converted into a fluorine using a fluoride
source, such as HF, KF, CuF, AgF, BF3, or HBF4.7 However,
this method is not always applicable because frameworks that
have small rings, multiple bonds, and/or low- and hypervalent
species are labile when exposed to the fluoride source.
We recently developed [o-(fluorodimethylsilyl)phenyl]-
lithium (1), which consists of an electrophilic fluorodi-
methylsilyl part and a nucleophilic phenyllithium part, as a
useful tool for introducing a fluorosilyl moiety into the
frameworks of main group element compounds in a nucleo-
philic manner.8,9 Aryllithium 1 was prepared by Br-Li
exchange between o-(fluorodimethylsilyl)phenyl bromide
and tert-butyllithium at -78 °C and was reacted with
halosilanes to afford unsymmetrical, silicon-halogenated
disilylbenzenes.8 Treatment of 1 with a haloborane produced
a (fluorodimethylsilyl)borylbenzene that serves as a Si/B
heteronuclear bidentate Lewis acid.9
The fluorosilyl functionality plays an important role in
main group chemistry and organic synthesis because of its
unique properties. Whereas the Si-F bond is thermally stable
owing to its high bond energy,1 itischemically labiledue tothe
strong polarization (Siδþ-Fδ-) arising from the large differ-
ence in electronegativity between silicon and fluorine.2,3 Thus,
fluorosilyl groups are highly receptive toward nucleophiles,
forming pentacoordinate silicon species4 or initiating nucleo-
philic substitution reactions at silicon,5 which enables us to
perform further transformations. It is also known that fluoro-
silyl groups are able to coordinate to electron-deficient metals
and metalloids.6 Therefore, the introduction of the fluorosilyl
functionality into main group element compounds as well as
organic compounds is expected to open doors to new possi-
bilities utilizing these compounds.
A conventional method that incorporates a fluorosilyl group
into the framework of a main group element compound is as
follows: first, a rather inert hydro, amino, or alkoxysilyl group is
Then, we turned our attention to the reaction of 1 with
divalent species of heavier group 14 elements, the latter of
which also exhibit ambiphilic character.10 Here we report
that the reactions of 1 with GeCl2 and SnCl2 yield benzosi-
lagermacyclobutene 2 and benzosiladistannacyclopentene 3,
respectively, which bear two or more o-(fluorodimethylsilyl)-
phenyl groups on the cyclic linkages of group 14 elements.
*Corresponding author. E-mail: kawachi@sci.hiroshima-u.ac.jp.
(1) Shaw, C. F.; Allred, A. L. Organomet. Chem. Rev., A 1970, 5, 96.
(2) Pauling’s electronegativity: 3.98 for F; 1.90 for Si; and 2.01 for Ge:
Emsley, J. In The Elements, 2nd ed.; Oxford University Press: Oxford,
1992.
(3) C-F bonds are also labile in some cases, and fluorine-containing
organometallic compounds undergo intramolecular elimination of a
metal fluoride; see for example: (a) Amii, H.; Uneyama, K. Chem. Rev.
2009, 109, 2119. (b) Boche, G.; Lohrenz, C. W. Chem. Rev. 2001, 101, 697.
(b) Kottke, T.; Sung, K.; Lagow, R. J. Angew. Chem., Int. Ed. Engl. 1995,
34, 1517. (c) Bosold, F.; Zulauf, P.; Marsch, M.; Harms, K.; Lohrenz, J.;
Boche, G. Angew. Chem., Int. Ed. Engl. 1991, 30, 1455, and references
therein.
Results and Discussion
The reaction of 1 with GeCl2 dioxane (0.5 equiv) in Et2O was
3
conducted at -60 °C for 19 h to yield benzosilagermacyclobutene
(4) Dorsey, C. L.; Gabbaı, F. P. Organometallics 2008, 27, 3065, and
(7) Kunai, A.; Sakurai, T.; Toyoda, E.; Ishikawa, M. Organometallics
1996, 15, 2478, and references therein.
(8) Kawachi, A.;Tani, A.;Machida, K.;Yamamoto, Y.Organometallics
¨
references therein.
(5) Bassindale, A. R.; Taylor, P. G. In The Chemistry of Organic
Silicon Compounds; Patai, S., Rappoport, Z., Eds.; John Wiley & Sons:
Chichester, 1989; Chapter 13, pp 839-892.
(6) Recent examples: (a) Sievert, N.; Fischer, A.; Klingebiel, U.; Pal,
A.; Noltemeyer, M. Z. Anorg. Allg. Chem. 2007, 633, 1223. (b) Panisch,
R.; Bolte, M.; M€uller, T. J. Am. Chem. Soc. 2006, 128, 9676. (c) Molev, G.;
Bravo-Zhivotovskii, D.; Kami, D.; Tumanskii, B.; Botoshansky, M.;
Apeloig, Y. J. Am. Chem. Soc. 2006, 128, 2784.
2007, 26, 4697.
(9) Kawachi, A.; Tani, A.; Shimada, J.; Yamamoto, Y. J. Am. Chem.
Soc. 2008, 130, 4222.
€
(10) Recent examples: (a) Yao, S.; Wullen, C. v.; Sun, X.-Y.; Driess,
M. Angew. Chem., Int. Ed. 2008, 47, 3250. (b) Rupar, P. A.; Jennings, M. C.;
Ragogna, P. J.; Baines, K. M. Organometallics, 2007, 26, 4109, and
references therein.
r
2009 American Chemical Society
Published on Web 10/08/2009
pubs.acs.org/Organometallics

6348 Organometallics, Vol. 28, No. 21, 2009
Kawachi et al.
Scheme 1. Reactions of 1 with GeCl2 and SnCl2
2 together with a small amount of dimerized product7 4 (2:4=
81:19 by 1H NMR), as shown in Scheme 1. Recrystallization of
the reaction mixture from hexane afforded 2 in 55% yield as
colorless crystals. The temperature control is essential to yield 2
because at the higher temperatures 1 predominantly underwent
dimerization to give 4.11 The employment of 1 and GeCl2 in the
mole ratio of 1:1 gave a similar result (2:4=80:20).
Figure 1. Molecular structure of 2 with thermal ellipsoids set at
30% probability; hydrogen atoms are omitted for clarity.
Selected bond lengths [A] and angles [deg]: Ge1-Si1 =
2.371(3), Ge1-C1=1.986(9), Ge1-C9=1.973(9), Ge1-C17=
1.976(9), Si1-C2 = 1.890(10), C1-C2 = 1.405(12), Si2-F1 =
1.598(7), Si3-F2=1.592(6), F1 Ge1=3.096(6), F2 Ge2=
3.165(6), Ge1-C1-C2 = 102.9(6), C1-C2-Si1 = 106.0(7),
C2-Si1-Ge1=76.9(3), Si1-Ge1-C1=74.2(3), C9-Ge1-C17=
111.1(4), Ge1-C1-C2-Si1=0.2(6).
X-ray crystallographic analysis revealed that 2 has a
planar {Ge-Si-C-C} four-membered ring bearing two
o-(fluorodimethylsilyl)phenyl groups on the germanium
atom (Figure 1). The {Ge-Si-C-C} four-membered ring
has an almost planar conformation. The Ge1-Si1 bond
length of 2.371(3) A is consistent with normal Ge-Si sin-
gle-bond length. Acute angles of C1-Ge1-Si1 (74.2(3)°)
and C2-Si1-Ge1 (76.9(3)°) are necessitated by the forma-
3 3 3
3 3 3
Scheme 2. Plausible Reaction Pathways from 1 to 2 and 3
tion of the four-membered ring. F Ge1 atomic distances
3 3 3
(3.096(6) and 3.165(6) A) are within the sum of the van der
Waals radii of the two elements (3.38 A).12
In the 29Si{1H} NMR spectra, the endocyclic silicon atom
resonates at δ(29Si)=15.3 as a triplet owing to long-range
coupling to the two fluorine atoms on the exocyclic silicon
atoms (5J(29Si-19F)=9 Hz). The exocyclic silicon atom resonates
at δ(29Si)=21.1 as a doublet owing to 1J coupling to the one
fluorine atom (1J(29Si-19F)=283 Hz).
Scheme 2 shows a plausible reaction pathway to 2. The
reaction of 1 with GeCl2 produces diarylgermylene 5 and
subsequently (triarylgermyl)lithium 6.13,14 The low solubility
of GeCl2 dioxane in Et2O at low temperature may create the
3
condition where 1 is present in excess compared to GeCl2.
The germyl anion center in 6 intramolecularly attacks at one
of the fluorodimethylsilane moieties to furnish 2 (cyclization
(a) in Scheme 2). Additional THF (Et2O-THF (8:1)) in an
(11) As reported in our previous paper, 1 starts to dimerize between
-40 and -50 °C; see ref 8.
(12) van der Waals radii estimated by Pauling’s approximation: 1.40
A for F; 1.93 A for Si; 1.98 A for Ge; and 2.16 A for Sn: Bondi, A.
J. Phys. Chem. 1964, 68, 441.
(13) Examples of reactions of aryllithiums with Ge(II) or Sn(II)
species to form (triarylgermyl)lithiums or (triarylstannyl)lithiums:
€
(a) Veith, M.; Ruloff, C.; Huch, V.; Tollner, F. Angew. Chem., Int. Ed.
€
Engl. 1988, 27, 1381. (b) Drost, C.; Griebel, J.; Kirmse, R.; Lonnecke, P.;
Reinhold, J. Angew. Chem., Int. Ed. 2009, 48, 1962. (c) Eichler, B. E.;
Phillips, A. D.; Power, P. P. Organometallics 2003, 22, 5423, and references
therein.
attempt to increase the solubility of GeCl2, however, pro-
moted dimerization of 1 (2:4=36:64).
Next, 1 was allowed to react with SnCl2 under the same
reaction condition as the reaction with GeCl2, as shown in
Scheme 1. Recrystallization of the reaction mixture from
Et2O afforded benzosiladistannacyclopentene 3 in 18% yield
as colorless crystals. A trace amount of 4 was detected by 1H
NMR analysis of the reaction mixture (3:4 = 88:12). The
employment of 1 and SnCl2 in the mole ratio of 1:1 resulted in
a complex mixture involving 4.
(14) For reviews of triarylgermyl-alkali metals: (a) Riviere, P.;
R-Baudet, M.; Satge, J. In Comprehensive Organometallic Chemistry;
Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press, Ltd.: New
York, 1982; Vol. 2, Chapter 10, pp 399-518. (b) Riviere, P.; R-Baudet, M.;
Satge, J. In Comprehensive Organometallic Chemistry II; Davies, A. G.,
Ed.; Elsevier Science, Ltd.: Oxford, 1995; Vol. 2, Chapter 5, pp 137-216.
Recent examples: (c) Kawachi, A.; Tanaka, Y.; Tamao, K. Eur. J. Inorg.
€
Chem. 1999, 461. (d) Habereder, T.; Noth, H. Z. Anorg. Allg. Chem. 2001,
627, 1003. (e) Berg, D. J.; Lee, C. K.; Walker, L.; Bushnell, G.; W.
J. Organomet. Chem. 1995, 493, 47.

Article
Organometallics, Vol. 28, No. 21, 2009 6349
Table 1. Crystallographic Data for Compounds 2 and 3
2
3
formula
fw
C
513.34
200(2)
0.71069
colorless
24H30F2GeSi3
C43H50F5LiSi5Sn2
1046.60
200(2)
0.71069
colorless
temp/K
wavelengh/A
cryst color
cryst size/mm
cryst syst
space group
a/A
b/A
c/A
R/deg
β/deg
0.30 ꢀ 0.20 ꢀ 0.20 0.30 ꢀ 0.30 ꢀ 0.30
monoclinic
P21/n
monoclinic
P21/c
11.8690(2)
16.6950(3)
26.2210(3)
90
90.8900(10)
90
5195.14(14)
4
1.338
29.1530(9)
9.2050(2)
9.8930(3)
90
90.4270(10)
90
2654.75(13)
4
1.284
1.312
1064
γ/deg
V/A3
Z
F
calc/g cm-3
μ(Mo KR)/mm-1
F(000)
1.121
2104
Figure 2. Molecular structure of 3 with thermal ellipsoids set at
30% probability; hydrogen atoms are omitted for clarity.
Selected bond lengths [A] and angles [deg]: Sn1-Si1 =
2.5712(8), Sn1-Sn2 = 2.7595(2), Sn1-C9 = 2.180(3), Sn1-
C17 = 2.179(3), Sn2-C1 = 2.180(3), Sn2-C25 = 2.177(3),
Sn2-C33 = 2.174(3), Si1-C2 = 1.904(3), C1-C2 = 1.410(4),
Si2-F1 = 1.609(2), Si3-F2 = 1.611(2), Si4-F3 = 1.642(3),
θ range/deg
1.40-27.50
5982/0/278
1.079
0.1054, 0.3062
0.1205, 0.3095
1.40-27.50
11 577/0/471
1.161
0.0410, 0.1145
0.0497, 0.1215
0.654, -2.232
data/restraints/params
goodness of fit on F2
final R1, wR2 (I > 2σ(I))
final R1, wR2 (all data)
large diff peak and hole/e A-3 1.335, -1.261
observed. 4-Fluorobicyclo[2.2.2]oct-1-yltrimethylstannane,
in which orbital interaction between the two bridgehead
atoms is remarkable, exhibits a large 119Sn-19F coupling
constant (75 Hz).15b Intramolecular coordination of a fluor-
ine atom to a tin atom also results in large 119Sn-19F
coupling constants in tin(IV) compounds bearing 2,4,-
6-(CF3)3C6H2 or 2,6-(CF3)2C6H3 ligands (10-19 Hz)15c
and in [2-(stannyl)ferrocenyl]fluoroborate (99-372 Hz).15d
Thus, the observed large values in 3 can be ascribed to
through-space coupling. The atomic distances between
F1/F2 and Sn1 and F3/F4 and Sn2 are within the sum of
their van der Waals radii (see above); F1/F2 and F3/F4 can
get close to Sn2 and Sn1, respectively, because the aryl
groups are flexible in solution.
Formation of 3 can be explained as shown in Scheme 2. In
a similar manner to the reaction with GeCl2, diarylstanny-
lene 7 and subsequently (triarylstannyl)lithium 8 are formed
in situ.13,16 The ring-closing reaction in 8 to give benzosilas-
tannacyclobutene 9 is, however, so slow, perhaps owing to a
longer Sn-C single bond than the Ge-C single bond,17 that
one more equivalent of 7 may insert into the Sn-Li bond in 8
to generate (distannyl)lithium 10 (path A in Scheme 2). Then
10 undergoes a ring-closing reaction by intramolecular nu-
cleophilic attack of the distannyl anion at one of the fluoro-
dimethylsilane moieties on the β-tin atom to produce 3
(cyclization (b) in Scheme 2). There may be an alternative
mechanism,18 in which 9 is formed in a manner similar to 2,
and 7 inserts into the reactive Sn-Si bond in 9 to provide 3
Si5-F4 = 1.603(3), F1 Sn1 = 3.0787(19), F2 Sn1 =
3 3 3 3 3 3
3.087(2), F3 Sn2 = 3.063(3), F4 Sn2 = 3.1380(19),
3 3 3
3 3 3
Si1-Sn1-Sn2 = 88.367(18), Sn1-Sn2-C1 = 96.86(7), Sn2-
C1-C2 = 121.65(19), C1-C2-Si1 = 127.1(2), C2-Si1-Sn1 =
106.00(8), C9-Sn1-C17 = 102.40(10), C25-Sn2-C33 =
103.30(10), C1-Sn2-Sn1-Si1=-0.18(7), C2-Si1-Sn1-Sn2=
-0.11(9).
The molecular structure of 3 was unambiguously deter-
mined by X-ray crystallographic analysis (Figure 2). 3 has a
planar five-membered ring bearing two o-(fluorodimethyl-
silyl)phenyl groups on each tin atom. Whereas the Si1-Sn1
bond length of 2.5712(8) A is consistent with normal Si-Sn
single-bond lengths, the Sn1-Sn2 bond length of 2.7595(2)
A is slightly shorter than a normal Sn-Sn single bond.
Atomic distances between each fluorine atom and the nearest
tin atom (3.063(3)-3.1380(9) A) are within the sum of the
van der Waals radii of the two elements (3.56 A).12 Whereas
the interior angle at Si1 (106.00(8)°) is almost equal to angles
in the ideal tetrahedral geometry at the silicon atom (109.5°),
the interior angles at Sn1 (88.367(18)°) and Sn2 (96.86(7)°)
are acute.
The 29Si{1H} NMR spectra showed that the endocyclic
silicon atom resonates with coupling to R- and β-tin atoms at
δ(29Si)=6.0 (1J(29Si-117/119Sn)=37 Hz, 2J(29Si-117/119Sn)=
6 Hz), while the two exocyclic silicon atoms resonate with
coupling to fluorine atoms at δ(29Si)=20.0 (d, 1J(29Si-19F)=
286 Hz) and 20.8 (d, 1J(29Si-19F)=286 Hz). The 119Sn{1H}
NMR spectra exhibited two sets of triplets of triplets at
5
(16) For reviews of triarylstannyl-alkali metals: (a) Davies, A. G.;
Smith, P. J. In Comprehensive Organometallic Chemistry; Wilkinson, G.,
Stone, F. G. A., Abel, E. W., Eds.; Pergamon Press, Ltd.: New York, 1982;
Vol. 2, Chapter 11, pp 519-627. (b) Davies, A. G. In Comprehensive
Organometallic Chemistry II; Davies, A. G., Ed.; Elsevier Science, Ltd.,
Oxford, 1995; Vol. 2, Chapter 6, pp 218-303. Recent examples: (c) Tice, J.
B.; Chizmeshya, A. V. G.; Groy, T. L.; Kouvetakis, J. Inorg. Chem. 2009, 48,
6314. (d) Neale, N. R.; Tilley, T. D. J. Am. Chem. Soc. 2005, 127, 14745.
-167.64 (4J(119Sn-19F)=117 Hz, J(119Sn-19F)=99 Hz)
and -102.03 (4J(119Sn-19F)=142 Hz, 5J(119Sn-19F)=128
5
Hz).15 Although long-range (4J or J) 119Sn-19F coupling
constants are usually less than 10 Hz,15a large values are also
(15) Examples of long-range or through-space Sn-F coupling:
(a) Barnard, M.; Smith, P. J.; White, R. F. M. J. Organomet. Chem.
1974, 77, 189. (b) Adcock, W.; Gangodawila, H.; Kok, G. B.; Iyer, V. S.
Organometallics 1987, 6, 156. (c) Batsanov, A. S.; Cornet, S. M.; Dillon, K.
B.; Goeta, A. E.; Thompson, A. L.; Xue, B. Y. Dalton Trans. 2003, 2496. (d)
Boshra, R.; Venkatasubbaiah, K.; Doshi, A.; Lalancette, R. A.; Kakalis, L.;
€
(e) Habereder, T.; Noth, H. Z. Anorg. Allg. Chem. 2001, 627, 789.
(17) (a) Sum of covalent bond radii: C þ Ge=1.99 A; C þ Sn=2.17 A;
see ref 2. (b) E-C(sp2) single-bond lengths in crystal structures of
Ar3ELi were reported to be 2.000-2.054 A for E=Ge and 2.209-2.211
A for E=Sn, according to the Cambridge Structural Database (ver. 5.3).
(18) We thank one of the reviewers for suggesting this mechanism.
€
Jakle, F. Inorg. Chem. 2007, 46, 10174.

6350 Organometallics, Vol. 28, No. 21, 2009
Kawachi et al.
(path B in Scheme 2). We could not determine whether 9 was
formed or not by 1H NMR analysis of the reaction mixture.
Attempted preparation of 7, which should be a key inter-
mediate in both mechanisms, by tuning the ratio of 1/SnCl2
was unsuccessful.
under a nitrogen atmosphere (99.999%). Et2O was distilled
under a nitrogen atmosphere over sodium diphenylketyl or
dehydrated Et2O (<50 ppm; Kanto Chemical Co., Inc.) and
was dried through a solvent dispensing system (GlassContour)
under a nitrogen atmosphere (99.999%). C6D6 was distilled
under a nitrogen atmosphere over sodium diphenylketyl. All
reactions were carried out under inert gas atmosphere.
Conclusion
Reaction of 1 with GeCl2 dioxane: 3,4-Benzo-2,2-bis[(2-
3
fluorodimethylsilyl)phenyl]-1,1-dimethyl-1-sila-2-germacyclobut-3-
ene (2). A solution of t-BuLi in pentane (1.58 mol/L, 2.1 mL,
3.3 mmol) was added dropwise to a solution of o-bromo-
(fluorodimethylsilyl)benzene (709 mg, 3.0 mmol) in Et2O
(6.0 mL) at -78 °C over 8 min, and the reaction mixture was
stirred at the same temperature for 0.5 h. To the resulting white
suspension of o-(fluorodimethylsilyl)phenyllithium (1) was
We demonstrated that o-(fluorosilyl)phenyl groups were
successfully introduced onto the cyclic linkages of heavier
group 14 elements. The reactions of 1 with GeCl2 and SnCl2
produced benzosilagermacyclobutene 2 and benzosiladis-
tannacyclopentene 3, bearing two or more o-(fluorodimethyl-
silyl)phenyl groups. To our knowledge, 2 and 3 are the first
examples of benzocyclobutene and benzocyclopentene ana-
logues incorporating two different heavier group 14 ele-
ments.19,20 The fluorosilyl functionality on 2 and 3 is
expected to open the door to new reaction modes of these
cyclic linkages, and further investigations are in progress at
our laboratory.
added GeCl2 dioxane (345 mg, 1.5 mmol) by portions over
3
5 min at -78 °C. The reaction mixture was allowed to warm
to -60 °C and stirred at that temperature for 19 h. The reaction
mixture was allowed to warm to room temperature and con-
centrated in vacuo. Hexane (3 mL) was added to the residue, and
the precipitated inorganic salts were filtered off. The filtrate was
concentrated in vacuo to give a mixture (512 mg) of 2 and 4 (2:4=
81:19 in 1H NMR spectra). The mixture was recrystallized from
hexane at -25 °C to afford 2 (286 mg, 55% yield) as colorless
crystals.
Experimental Section
General Procedures. 1H (400 MHz), 13C{1H} (100 MHz), 19
F
Mp: 128.0-129.0 °C (in a sealed tube). 1H NMR (C6D6, δ):
-0.040 (d, 3J(1H-19F)=8 Hz, 6H), 0.083 (d, 3J(1H-19F)=8 Hz,
6H), 0.65 (s, 6H), 7.13 (ddd, J=7, 1, and 1 Hz, 2H), 7.22 (ddd, J=
7, 7, and 1 Hz, 2H), 7.32 (ddd, J=7, 7, and 1 Hz, 1H), 7.36 (dd,
J=7 and 1 Hz, 2H), 7.46 (ddd, J=7, 7, and 1 Hz, 1H), 7.51 (ddd,
J=7, 1, and 1 Hz, 1H), 8.21 (d, J=7 Hz, 2H), 8.42 (d, J=7 Hz,
1H). 13C{1H} NMR (C6D6, δ): -0.56 (SiMe2), -0.21 (d,
(376 MHz), 29Si{1H} (79.4 MHz), and 119Sn{1H} NMR (149.0
MHz) NMR spectra were recorded with a JEOL EX-400 or AL-
400 spectrometer. 1H chemical shifts in C6D6 were referenced to
the residual proton (δ=7.20). 13C chemical shifts were refer-
enced to internal C6D6 (δ=128.0) or external tetramethylsilane
(δ=0). 19F chemical shifts were referenced to external CFCl3
(δ=0). 29Si chemical shifts were referenced to external tetra-
methylsilane (δ=0). 119Sn chemical shifts were referenced to
external tetramethylstannane (δ=0). The mass spectra (EI) were
measured at 70 eV with a JEOL SX-102A mass spectrometer at
the Natural Science Center for Basic Research and Develop-
ment (N-BARD), Hiroshima University: we thank Dr. Daisuke
Kajiya for the measurement of the samples. Melting points were
measured with a Yanaco micro melting point apparatus and are
uncorrected. The elemental analyses were performed using a
Perkin-Elmer 2400CHN elemental analyzer at our laboratory.
tert-Butyllithium in pentane was purchased from Kanto
2
2J(13C-19F)=14 Hz, SiMe2F), 0.03 (d, J(13C-19F)=14 Hz,
SiMe2F), 127.93 (d, 4J(13C-19F) = 2 Hz, CH), 128.97 (CH),
3
129.45 (CH), 130.31 (CH), 132.71 (CH), 134.24 (d, J(13C-19
4
F)=6 Hz, CH), 134.37 (d, J(13C-19F)=6 Hz, CH), 138.55
5
2
(d, J(13C-19F)=2 Hz, CH), 142.96 (d, J(13C-19F)=17 Hz,
C-SiMe2F), 147.08 (t, J(13C-19F) = 2 Hz, C-SiMe2), 156.41
6
(C-Ge), 158.93 (t, 5J(13C-19F)=4 Hz, C-Ge). 19F NMR (C6D6,
δ): -155.79 (sept, 3J(1H-19F)=8 Hz). 29Si{1H} NMR (C6D6,
5
1
δ): 15.29 (t, J(29Si-19F)=9 Hz), 21.08 (d, J(29Si-19F)=283
Hz). MS (EI): m/z 515 (Mþ(for 74Ge) þ 1, 39), 513 (Mþ(for
72Ge) þ 1, 28), 511 (Mþ(for 70Ge) þ 1, 20), 437 {Mþ(for 74Ge) -
[SiMe2F], 84}, 435 {Mþ(for 72Ge) - [SiMe2F], 60}, 433 {Mþ(for
70Ge) - [SiMe2F], 42}, 377 (100), 375 (71), 373 (49). Anal. Calcd
for C24H30F2GeSi3: C, 56.15; H, 5.89. Found: C, 55.96; H, 5.87.
Reaction of 1 with SnCl2: 4,5-Benzo-2,2,3,3-tetrakis[(2-
fluorodimethylsilyl)phenyl]-1,1-dimethyl-1-sila-2,3-distannacy-
clopent-4-ene (3). A solution of t-BuLi in pentane (1.58 mol/L,
2.1 mL, 3.3 mmol) was added dropwise to a solution of
o-bromo(fluorodimethylsilyl)benzene (711 mg, 3.0 mmol) in
Et2O (6.0 mL) at -78 °C over 7 min, and the reaction mixture
was stirred at the same temperature for 0.5 h. To the resulting
white suspension of o-(fluorodimethylsilyl)phenyllithium (1)
was added SnCl2 (285 mg, 1.5 mmol) by portions over 7 min
at -78 °C. The reaction mixture was allowed to warm to -60 °C
and stirred at that temperature for 19 h. The reaction mixture
was allowed to warm to room temperature and concentrated in
vacuo. Hexane (3 mL) was added to the residue, and the
precipitated inorganic salts were filtered off. The filtrate was
concentrated in vacuo to give a mixture (586 mg) of 3 and 4 (3:4=
88:12 in 1H NMR spectra). The mixture was recrystallized from
Et2O at -25 °C to afford 3 (109 mg, 18% yield) as colorless
crystals.
Chemical Co., Inc. GeCl2 dioxane was prepared in a manner
3
similar to the procedure in the literature.21 SnCl2 (>90.0%;
Kanto Chemical Co., Inc.) was dried by an azeotropic distilla-
tion with EtOH (15 wt %) and 1,2-dichloroethane (85 wt %),
and the obtained anhydrous precipitate was washed with 1,2-
dichloroethane and dried in vacuo at 80 °C overnight.22 Hexane
was distilled under nitrogen atmosphere over calcium hydride or
dehydrated solvent (<10 ppm; Kanto Chemical Co., Inc.) and
was dried through a solvent dispensing system (GlassContour)
(19) Recent examples of disilacyclobutenes: (a) Naka, A.; Ikadai, J.;
Sakata, J.; Miyahara, I.; Hirotsu, K.; Ishikawa, M. Organometallics
2004, 23, 2397. (b) Wiberg, N.; Niedermayer, W.; Polborn, K. Z. Anorg.
Allg. Chem. 2002, 628, 1045. (c) Kyushin, S.; Kitahara, T.; Tanaka, R.;
Takeda, M.; Matsumoto, T.; Matsumoto, H. Chem. Commun. 2001, 2714.
Recent examples of digermacyclobutenes: (d) Komoriya, H.; Kato, M.;
Nakadaira, Y. Organometallics 1996, 15, 2014. See also ref 14e
.
(20) Recent examples of trisilacyclopentenes: (a) Naka, A.; Hayashi,
M.; Okazaki, S.; Ishikawa, M. Organometallics 1994, 13, 4994. (b) Ando,
W.; Hatano, K.; Urisaka, R. Organometallics 1995, 14, 3625. (c) Igarashi,
M.; Ichinohe, M.; Sekiguchi, A. Chem. Lett. 2007, 36, 1158. Recent
examples of trigermacyclopentenes: (d) Komoriya, H.; Kako, M.; Nakadaira,
Y.; Mochida, K. J. Organomet. Chem. 2000, 611, 420.
Mp: 196.0-197.0 °C (in a sealed tube). 1H NMR (C6D6, δ):
-0.42 (d, 3J(1H-19F) = 7 Hz, 6H), -0.12 (br, 6H), 0.18 (d,
3J(1H-19F)=7 Hz, 6H), 0.25 (d, 3J(1H-19F)=7 Hz, 6H), 0.95
(s, 6H), 6.95 (ddd, J=7, 7, and 1 Hz, 2H), 7.02-7.23 (m, 9H),
7.23-7.32 (m, 3H), 7.72 (d, J=7 Hz, 1H), 7.90 (d, J=7 Hz,
1H), 8.00-8.20 (br, 4H). 13C{1H} NMR (C6D6, δ): -0.65
(21) (a) Kouvetakis, J.; Haaland, A.; Shorokhov, D. J.; Volden, H.
V.; Girichev, G. V.; Sokolov, V. I.; Matsunaga, P. J. Am. Chem. Soc.
1998, 120, 6738. (b) Fjeldberg, T.; Haaland, A.; Schilling, B. E. R.; Lappert,
M.; Thorne, A. J. J. Chem. Soc., Dalton Trans. 1986, 1551.
(22) Synthetic Methods of Organometallic and Inorganic Chemistry;
Hermann, W. A., Ed.; Auner, N., Klingebiel, U., Vol. Eds.; Thieme: New
York, 1996; Vol. 2, pp 271-272.

Article
Organometallics, Vol. 28, No. 21, 2009 6351
2
2
(d, J(13C-19F)=15 Hz, CH3), 0.23 (d, J(13C-19F)=14 Hz,
CH3), 1.06 (d, 2J(13C-19F)=14 Hz, CH3), 2.97 (s, CH3), 127.02
(d, J=3 Hz, CH), 127.33 (d, J=2 Hz, CH), 127.48 (s, CH),
127.67 (s, CH), 128.30 (d, J=2 Hz, CH), 129.51 (d, J=12 Hz,
CH), 133.30 (d, J=6 Hz, CH), 133.67 (d, J=6 Hz, CH), 134.12
(s, CH), 138.72 (s, CH), 139.05 (s, CH), 142.00 (br, CH), 145.23
(d, J=15 Hz, C), 145.58 (d, J=16 Hz, C), 147.80 (s, C), 151.44
(s, C), 154.22 (s, C), 157.44 (t, J=7 Hz, C). 19F NMR (C6D6, δ):
-155.44 (s), -150.0 (br). 29Si{1H} NMR (C6D6, δ): 5.99
radiation (λ=0.71069 A). The data were solved using SHELX
by direct methods. The non-hydrogen atoms were refined
anisotropically. All of the hydrogen atoms unless otherwise
noted were located at the expected positions by geometrical
calculations and refined isotropically. The crystals of 3 include a
hexane and a LiF in the unit cell. Positions of the hydrogens in
the hexane are not determined. The fluorine in the LiF is
disordered. Crystallographic details of 2 and 3 are given in
Table 1.
(1J(29Si-117/119Sn) = 37 Hz, J(29Si-117/119Sn) = 6 Hz), 19.96
2
1
1
(d, J(29Si-19F)=286 Hz), 20.84 (d, J(29Si-19F)=286 Hz).
Acknowledgment. This work was partly supported by a
Grant-in-Aid for Scientific Research on Priority Area
“Advanced Molecular Transformations of Carbon Re-
sources” (No. 19020048) from the Ministry of Education,
Culture, Sports, Science and Technology, Japan. We also
thank Mr. Daisuke Kajiya, the Natural Science Center
for Basic Research and Development (N-BARD), Hir-
oshima University, for measurement of mass spectra.
119Sn{1H} NMR (C6D6, δ): -167.64 (tt, 4J(119Sn-19F)=117 Hz,
5J(119Sn-19F)=99 Hz), -102.03 (tt, J(119Sn-19F)=142 Hz,
4
5J(119Sn-19F)=128 Hz). MS (EI): m/z 984 (Mþ[119Sn], 1), 969
(Mþ[119Sn] - Me, 0.4), 830 (Mþ[119Sn] - 2SiMe2F, 3), 273
(o-C6H4(SiMe2F)[119Sn], 100), 77 (SiMe2F, 27). Anal. Calcd for
C40H50F4Si5Sn2: C, 48.79; H, 5.12. Found: C, 48.48; H, 5.11.
X-ray Crystallographic Analysis. Crystals of 2 and 3 suitable
for X-ray crystallographic analysis were obtained by recrystal-
lization from hexane and Et2O, respectively. A crystal was
mounted using silicon oil to a cryoloop (Hampton Research).
The data were collected at 200 K on a Mac Science DIP2030
imaging plate equipped with graphite-monochromated Mo KR
Supporting Information Available: CIFs of compounds 2 and
3. This material is available free of charge via the Internet at
http://pubs.acs.org.