Synthesis and structures of two 9,10-dihydro-9,10-distannaanthracenes

Article abstract of DOI:10.1021/om000800i

The 9,9,10,10-tetramethyl- and 9,9,10,10-tetra-tert-butyl-9,10-dihydro-9,10-distannaanthracenes have been synthesized and characterized. The X-ray crystallographic analysis of 9,10-dihydro-9,10-distannaanthracenes showed that the central tricyclic framework of the tetramethyl derivative has a butterfly conformation with a dihedral angle of 143°, while the central six-membered ring of the tetra-tert-butyl derivative has a planar structure. The synthesis and structure of a novel tribenzostannepin are also described.

Full text of DOI:10.1021/om000800i

Organometallics 2001, 20, 749-753
749
Syn th esis a n d Str u ctu r es of Tw o
9,10-Dih yd r o-9,10-d ista n n a a n th r a cen es
Masaichi Saito,* Minehiko Nitta, and Michikazu Yoshioka
Department of Chemistry, Faculty of Science, Saitama University, Shimo-okubo, Urawa,
Saitama, 338-8570 J apan
Received September 18, 2000
The 9,9,10,10-tetramethyl- and 9,9,10,10-tetra-tert-butyl-9,10-dihydro-9,10-distannaan-
thracenes have been synthesized and characterized. The X-ray crystallographic analysis of
9,10-dihydro-9,10-distannaanthracenes showed that the central tricyclic framework of the
tetramethyl derivative has a butterfly conformation with a dihedral angle of 143°, while
the central six-membered ring of the tetra-tert-butyl derivative has a planar structure. The
synthesis and structure of a novel tribenzostannepin are also described.
In tr od u ction
without synthetic and structural details.9,10 We report
herein the first synthesis and structures of 9,9,10,10-
tetramethyl- and 9,9,10,10-tetra-tert-butyl-9,10-dihydro-
9,10-distannaanthracenes. The conformation of the
central six-membered ring is found to be remarkably
dependent on substituents on each tin atom. The
synthesis and structure of the novel tribenzostannepin
is also described.
Since the synthesis of 9,9,10,10-tetraphenyl-9,10-
dihydro-9,10-disilaanthracene,1 studies on the synthesis,
structures, and reactions of 9,10-dihydro-9,10-disilaan-
thracene have been developed.2 The corresponding
germanium analogues, 9,10-dihydro-9,10-digermaan-
thracenes, were also synthesized and characterized.3
One of the most interesting features of 9,10-dihydro-
9,10-dimetallaanthracene derivatives is their utility as
potential precursors for metal-containing reactive spe-
cies. Also of interest is the conformation of their central
six-membered ring. Very recently, fascinating silicon-
containing reactive species such as a bis(silyl anion)4
and a relatively stable silyl radical5 have been reported
to be derived from 9,10-dihydro-9,10-disilaanthracenes.
The conformation of the central ring of a 9,10-dihydro-
9,10-dimetallaanthracene is dependent on substituents
on the metal.5-7 The syntheses of 9,10-dihydro-9,10-
dimetallaanthracenes thus far reported are limited to
those having methyl or phenyl substituents on the
metal. Recently, 9,10-di-tert-butyl-9,10-dihydro-9,10-
disilaanthracene has been synthesized.5 However, a
9,10-dihydro-9,10-dimetallaanthracene having two bulky
substituents on both of the two central metal atoms has
not yet been reported. As for tin analogues, although a
few 9,10-dihydroanthracenes having a tin atom at the
10-position have been reported,6,8 only one report on the
9,10-dihydro-9,10-distannaanthracene is available, but
Resu lts a n d Discu ssion
Syn th esis of 9,9,10,10-Tetr a m eth yl-9,10-d ih yd r o-
9,10-d ista n n a a n th r a cen e (1). First we attempted to
synthesize 9,9,10,10-tetramethyl-9,10-dihydro-9,10-di-
stannaanthracene (1) by the direct coupling of 1,2-
dilithiobenzene, prepared from 1,2-bis(trimethylstan-
nyl)benzene,11 with an equimolar quantity of dimethyldi-
chlorostannane. However, this reaction was unsuccess-
ful. Next, the direct coupling of 1,2-dibromobenzene with
dimethyldichlorostannane was attempted. Treatment of
an equimolar mixture of 1,2-dibromobenzene and di-
methyldichlorostannane with magnesium activated by
1,2-dibromoethane gave 9,9,10,10-tetramethyl-9,10-di-
hydro-9,10-distannaanthracene (1) in 5% yield. The
yield of 1 was improved by the following stepwise
method (Scheme 1). (2-Bromophenyl)lithium (2 equiv)
prepared by the reaction of 1,2-dibromobenzene with
n-butyllithium at -110 °C was treated with dimethyl-
dichlorostannane to give bis(2-bromophenyl)dimethyl-
stannane (2), the structure of which was determined by
spectral data and finally confirmed by X-ray structural
analysis. When a THF solution of 2 was treated with
magnesium in the presence of a catalytic amount of
copper(I) cyanide12 under reflux for 1.5 h, the solution
turned dark brown. Addition of dimethyldichlorostan-
nane to this solution, followed by heating at reflux for
* Corresponding author. E-mail: masaichi@chem.saitama-u.ac.jp.
(1) (a) Gilman, H.; Zuech, E. A. J . Am. Chem. Soc. 1960, 82, 3605.
(b) Gilman, H.; Zuech, E. A.; Steudel, W. J . Org. Chem. 1962, 27, 1836.
(2) For a review, see: Barton, T. J . Comprehensive Organometallic
Chemistry, 1st ed.; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.;
Pergamon Press: Elmsford, NY, 1982; Vol. 2, p 273.
(3) D’yachenko, O. A.; Soboleva, S. V.; Atovmyan, L. O. Zh. Strukt.
Khim. 1976, 17, 496.
(4) (a) Ando, W.; Hatano, K.; Urisaka, R. Organometallics 1995, 14,
3625. (b) Hatano, K.; Morihashi, K.; Kikuchi, O.; Ando, W. Chem. Lett.
1997, 293.
(5) Kyushin, S.; Shinnai, T.; Kubota, T.; Matsumoto, H. Organome-
tallics 1997, 16, 3800.
(6) McCarthy, W. Z.; Corey, J . Y.; Corey, E. R. Organometallics 1984,
3, 255.
(7) See references cited in ref 6.
(9) Lanthier, G. F.; Miller, J . M.; Cohen, S. C.; Massey, A. G. Org.
Mass Spectrom. 1974, 235.
(10) 9,10-Distannatriptycene has been synthesized and character-
ized, see: Dam, M. A.; Akkerman, O. S.; de Kanter, F. J . J .;
Bickelhaupt, F.; Veldman, N.; Spek, A. L. Chem. Eur. J . 1996, 2, 1139.
(11) Eisch, J . J .; Kotowicz, B. W. Eur. J . Inorg. Chem. 1998, 761.
(12) (a) Shirahata, A. Tetrahedron Lett. 1989, 30, 6393. (b) Lennon,
P. J .; Mack, D. P.; Thompson, Q. E. Organometallics 1989, 8, 1121.
(8) J utzi, P. Chem. Ber. 1971, 104, 1455.
10.1021/om000800i CCC: $20.00 © 2001 American Chemical Society
Publication on Web 01/26/2001

750 Organometallics, Vol. 20, No. 4, 2001
Saito et al.
gether with stannafluorene 415 (Scheme 2). The struc-
ture of 3 was established by X-ray crystallographic
analysis. An ORTEP drawing of 3 is shown in Figure 2
with selected bond lengths and angles. The central
seven-membered ring has a boat conformation. To the
best of our knowledge, tribenzostannepin 3 is the first
example of a tribenzo-fused stannepin, although several
stannepins have been synthesized.16 In the 1H NMR
spectrum of 3, there appeared two signals assignable
to the hydrogens of tert-butyl groups, and these signals
did not coalesce at 60 °C, suggesting the rigid comfor-
mation of 3, as in the case of tribenzosilepin.17 Although
the mechanism for the formation of 3 is still unclear,
the tribenzo skeleton of 3 was reasonably assumed to
be formed by successive couplings of benzyne generated
from 2-bromophenyllithium with 1,2-dibromobenzene.18
Syn th esis a n d Str u ctu r e of 9,9,10,10-Tetr a -ter t-
b u t yl-9,10-d ih yd r o-9,10-d ist a n n a a n t h r a cen e (5).
Since the reaction of (2-bromophenyl)lithium with di-
tert-butyldichlorostannane under the conditions de-
scribed above gave 3, to suppress the generation of
benzyne from (2-bromophenyl)lithium, the reaction of
(2-bromophenyl)lithium with di-tert-butyldichlorostan-
nane was conducted at low temperature. After treat-
ment of (2-bromophenyl)lithium with an equimolar
amount of di-tert-butyldichlorostannane at -110 °C, the
reaction was quenched with aqueuos NH4Cl at the same
temperature. After hydrolytic workup, di-tert-butyl(2-
bromophenyl)chlorostannane (6) was obtained in 39%
yield (Scheme 2), the structure of which was determined
by spectral data and elemental analysis. The formation
of 6 prompted us to examine its self-coupling. Reaction
of 6 with tert-butyllithium (2.2 equiv) afforded the self-
coupling product, 9,9,10,10-tetra-tert-butyl-9,10-dihydro-
9,10-distannaanthracene (5), in 70% yield. The structure
Sch em e 1
2 h, gave a dark green solution. After hydrolytic workup
and subsequent column chromatography (silica gel
elution with hexane), 9,9,10,10-tetramethyl-9,10-dihy-
dro-9,10-distannaanthracene (1) was obtained in 25%
yield.
Str u ctu r e of 1. The X-ray crystallographic analysis
of 1 was carried out at 203 K. An ORTEP drawing of 1
is shown in Figure 1 with selected bond lengths and
angles. There are two molecules in the unit cell. The
central six-membered ring has a boat comformation, and
hence the tricyclic framework has a butterfly conforma-
tion with a dihedral angle of 143 °, which is the smallest
among those of 9,10-dihydro-9,10-dimetallaanthracenes
of group 14 metals.3,13 The dihedral angle becomes
smaller as the atomic number of the group 14 elements
increases (Table 1) in the series of 9,10-dihydro-9,10-
dimetallaanthracene derivatives of group 14 elements.
Although the dependence of the dihedral angle on the
metal is not well understood, it probably results from a
balance of axial-axial interaction and equatorial peri-
protons interaction. Interestingly, one of the aromatic
moieties of each of the two molecules in the unit cell is
face to face with the other like a π-dimer14 with a
distance of about 4 Å. Since the ORTEP drawing of 1
shows that each tin has pseudoaxial and pseudoequa-
torial methyl substituents, its 1H NMR spectrum is
anticipated to show two signals for these nonequivalent
methyl groups. However, there appeared only a singlet
assignable to methyl hydrogens at δ 0.47, which did not
change significantly in the temperature range from 20
to -70 °C. It is reasonably assumed that a rapid boat-
to-boat inversion occurs in solution as in the case of
other tetramethyl derivatives.7
1
of the latter was determined from its H and 13C NMR
spectra and elemental analysis (Scheme 3). The forma-
tion of 5 is worthy of note from the standpoint of the
first 9,10-dihydro-9,10-dimetallaanthracene having two
bulky groups on both of the central metals. The X-ray
crystallographic analysis of 5 showed that the central
six-membered ring had a planar structure, preventing
a pseudoaxial orientation of the tert-butyl groups, in
sharp contrast to the dimethyl derivative, which has a
butterfly conformation (Figure 3).
Con clu sion
The synthesis and structures of the 9,10-dihydro-9,10-
distannaanthracenes were reported. The conformation
of the central six-membered ring is remarkably depend-
ent on the substituents on the tin. The central tricyclic
framework of the tetramethyl derivative has a butterfly
conformation with a dihedral angle of 143°, while that
of the tetra-tert-butyl derivative has a planar structure,
probably due to steric reasons.
In tr od u ction of ter t-Bu tyl Gr ou p s on th e Tin :
F or m a t ion of t h e Novel Tr iben zost a n n ep in . The
synthesis of the 9,10-dihydro-9,10-distannaanthracene
having two tert-butyl groups on both of the two tin
atoms was also investigated. First, we have attempted
to synthesize bis(2-bromophenyl)di-tert-butylstannane
by the reaction of di-tert-butyldichlorostannane with (2-
bromophenyl)lithium using the method applied in the
preparation of the methyl derivative; that is, (2-bro-
mophenyl)lithium (2 equiv) was treated with di-tert-
butyldichlorostannane, and then the mixture was
warmed to room temperature. However, an unantici-
pated product, tribenzostannepin 3, was obtained to-
The generation of tin-containing reactive species from
these newly obtained 9,10-dihydro-9,10-distannaan-
thracenes is currently in progress.
(15) For a review of the related compounds, see: Dubac, J .; Lapor-
terie, A.; Manuel, G. Chem. Rev. 1990, 90, 215.
(16) For the first C-unsubstituted stannepin, see: Nakadaira, Y.;
Sato, R.; Sakurai, H. J . Organomet. Chem. 1992, 441, 411.
(17) Corey, J . Y.; Corey, E. R. Tetrahedron Lett. 1972, 4669.
(18) Chen, L. S.; Chen, G. J . J . Organomet. Chem. 1980, 193, 283.
(13) D’yachenko, O. A.; Atovmyan, L. O.; Soboleva, S. V. Zh. Strukt.
Khim. 1975, 16, 505.
(14) Miller, L. L.; Mann, K. R. Acc. Chem. Res. 1996, 29, 417.

9,10-Dihydro-9,10-distannaanthracenes
Organometallics, Vol. 20, No. 4, 2001 751
F igu r e 1. ORTEP drawing of 1 with thermal ellipsoid plots (40% probability for non-hydrogen atoms). One of these
molecules in the unit cell (left) and the side view of the unit cell (right). Selected bond lengths (Å) and angles (deg): Sn-
(1)-C(1), 2.120(8); Sn(1)-C(12), 2.122(9); Sn(2)-C(6), 2.138(6); Sn(2)-C(7), 2.155(8); C(1)-Sn(1)-C(12), 107.2(4); C(6)-
Sn(2)-C(7), 107.1(3); Sn(1)-C(1)-C(6), 121.9(6); Sn(1)-C(12)-C(7), 122.9(6); Sn(2)-C(6)-C(1), 121.6(6); Sn(2)-C(7)-
C(12), 120.8(6).
Ta ble 1. Dih ed r a l An gles of
9,10-Dih yd r o-9,10-d im eta lla a n th r a cen es
M
dihedral angle (deg)
Si
Ge
Sn
156a
152b
143c
a
c
Ref 13. bRef 3. This work.
Sch em e 2
F igu r e 2. ORTEP drawing of 3 with thermal ellipsoid
plots (40% probability for non-hydrogen atoms). Selected
bond lengths (Å) and angles (deg): Sn(1)-C(1), 2.147(4),
Sn(1)-C(18), 2.177(4); C(1)-C(6), 1.406(5); C(6)-C(7),
1.505(6); C(7)-C(12), 1.397(5); C(12)-C(13), 1.534(5); C(13)-
C(18), 1.367(5); C(1)-Sn(1)-C(18), 95.7(2); C(19)-Sn(1)-
C(23), 113.5(2).
Sch em e 3
Exp er im en ta l Section
Gen er a l P r oced u r e. All reactions were carried out under
argon. THF and diethyl ether used in the synthesis were
distilled from sodium benzophenone ketyl under argon atmos-
phere before use. Magnesium (turnings) was purchased from
1
Wako Pure Chemical Industries, Ltd. H (400 MHz) and 13C
Dir ect Syn th esis of 9,9,10,10-Tetr a m eth yl-9,10-d ih y-
d r o-9,10-d ista n n a a n th r a cen e (1). A THF (7 mL) solution
of 1,2-dibromoethane (1.6 mL, 18.6 mmol) with magnesium
(559 mg, 23.0 mmol) was heated at reflux for 15 min. To this
mixture then was added in succession, with stirring, a THF
(2 mL) solution of 1,2-dibromobenzene (0.36 mL, 2.98 mmol)
and a THF (3 mL) solution of dimethyldichlorostannane (663
mg, 3.02 mmol). After the mixture had been stirred and heated
at reflux for 1.5 h, aqueous NH4Cl was added, and the
resulting mixture was extracted with diethyl ether. After
removal of ether, the residue was subjected to FCC (hexane)
to afford 9,9,10,10-tetramethyl-9,10-dihydro-9,10-distannaan-
thracene (1) (32 mg, 5%). 1: mp 101 °C (recrystallization from
methanol). 1H NMR: δ 0.47(s, 12H), 7.27-7.30(m, 4H), 7.54-
NMR (100 MHz) spectra were recorded on a Bruker AM-400
or an ARX-400 spectrometer in CDCl3 with tetramethylsilane
as an internal standard. Flash column chromatography (FCC)
and wet column chromatography (WCC) were carried out with
Wako gel C-300 and Merck Kieselgel 60 (SiO2) or Merck
aluminum oxide 90 (Al2O3). All melting points were determined
on a Mitamura Riken Kogyo MEL-TEMP apparatus and are
uncorrected. Elemental analyses were carried out at the
Microanalytical Laboratory of Chemical Analytical Center,
Saitama University. Data for the X-ray crystallographic
analyses were collected on Mac Science Xdip or MXC18K
diffractometers with Mo KR radiation (λ ) 0.71073 Å), and
the structures were solved by direct methods.

752 Organometallics, Vol. 20, No. 4, 2001
Saito et al.
F igu r e 3. ORTEP drawing of 5 with thermal ellipsoid plots (40% probability for non-hydrogen atoms). One of these
molecules in the unit cell (left) and the side view (right). Selected bond lengths (Å) and angles (deg): Sn(1)-C(1), 2.149(2);
Sn(1)-C(6), 2.145(3); Sn(1)-C(7), 2.197(4); Sn(1)-C(11), 2.187(3); C(1)-Sn(1)-C(6), 111.4(1), C(7)-Sn(1)-C(11), 116.4(2).
7.56(m, 4H); 13C NMR: δ -8.34(q), 128.19(d), 135.79(d),
152.07(s). Anal. Calcd for
Found: C, 43.32; H, 4.44.
mg, 4%). 3: mp 216-217 °C (recrystallization from methylene
chloride).
C
16H20Sn2: C, 42.73; H, 4.48.
1H NMR: δ 0.81(s, 9H), 1.59(s, 9H), 7.18-7.39(m,
10H), 7.61-7.74(m, 2H). 13C NMR: δ 29.43(s), 31.67(q), 32.02-
(q), 125.51(d), 127.05(d), 128.35(d), 131.21(d), 133.68(d), 134.69-
(d), 143.32(s), 146.65(s), 149.48(s). Anal. Calcd for C26H30Sn:
C, 67.71; H, 6.66. Found: C, 67.70; H, 6.59. 4: mp 40.5-41.5
Step w ise Syn th esis of 9,9,10,10-Tetr a m eth yl-9,10-d i-
h yd r o-9,10-d ista n n a a n th r a cen e (1). (1) P r ep a r a tion of
Bis(2-br om op h en yl)d im eth ylsta n n a n e (2). To a solution
of n-butyllithium (1.53 M in hexane; 3.92 mL, 6.00 mmol) in
a mixture of THF (15 mL) and diethyl ether (15 mL) was added
1,2-dibromobenzene (0.71 mL, 5.89 mmol) at -110 °C, and the
resulting solution was stirred at this temperature for 2.5 h.
Subsequently, dimethyldichlorostannane (661 mg, 3.01 mmol)
in THF (5 mL) and diethyl ether (5 mL) was added at -110
°C. The reaction mixture was allowed to warm to room
temperature overnight. Then aqueous NH4Cl (saturated, 15
mL) was added, and the mixture was extracted with diethyl
ether. After removal of volatile components, the residue was
subjected to WCC (SiO2, hexane) to give bis(2-bromophenyl)-
dimethylstannane (2) (1127 mg, 83%). 2: mp 46-47 °C
1
°C (recrystallization from hexane). H NMR: δ 1.30(s, 18H),
7.23-7.26(m, 2H), 7.34-7.40(m, 2H), 7.56-7.58(m, 2H), 7.92
(d, J ) 8 Hz, 2H). 13C NMR: δ 31.25(s), 31.47(q), 122.56(d),
127.15(d), 128.77(d), 136.42(d), 141.49(s), 149.46(s). Anal.
Calcd for C20H26Sn: C, 62.37; H, 6.81. Found: C, 62.60; H,
6.85.
P r ep a r a tion of (2-Br om op h en yl)d i-ter t-bu tylch lo-
r osta n n a n e (6). To 1,2-dibromobenzene (1.08 mL, 8.95 mmol)
in THF (10 mL) and diethyl ether (10 mL) was added
n-butyllithium (1.50 M in hexane, 6.07 mL, 9.11 mmol) at
-110 °C. The resulting mixture was stirred for 2 h at this
temperature. Addition of di-tert-butyldichlorostannane (2.765
g, 9.10 mmol) in THF (5 mL) and diethyl ether (5 mL) at -110
°C followed. The reaction mixture was stirred for 2 h at -110
°C, and subsequently the reaction was quenched with aqueous
NH4Cl at the same temperature. The organic layer was
extracted with ether. After removal of volatile components
under reduced pressure and removal of unreacted di-tert-
butyldichlorostannane by recrystallization from hexane, the
residue was purified by recrystallization from methanol to
afford (2-bromophenyl)di-tert-butylchlorostannane (6) (1.495
1
(recrystallization from hexane-methanol, 10:1). H NMR: δ
0.71(s, 6H), 7.18-7.29(m, 4H), 7.32-7.35(m, 2H), 7.52-7.55(m,
2H). 13C NMR: δ -6.06(q), 126.63(d), 130.61(d), 131.80(d),
132.75(s), 138.31(d), 145.10(s). Anal. Calcd for C14H14Br2Sn:
C, 36.49; H, 3.06. Found: C, 36.76; H, 3.01.
(2) P r ep a r a tion of 1 fr om 2. Compound 2 (1843 mg, 4.00
mmol), magnesium (195 mg, 8.02 mmol), and a catalytic
amount of copper(I) cyanide (31 mg) in 20 mL of THF were
stirred and heated at reflux for 1.5 h. Subsequently, a THF
(10 mL) solution of dimethyldichlorostannane (967 mg, 4.40
mmol) was added. After the mixture had been heated at reflux
for 2 h, aqueous NH4Cl was added. The resulting mixture was
extracted with diethyl ether. After removal of ether, the
residue was subjected to WCC (SiO2, hexane) to afford 1 (454
mg, 25%). The compound 1 obtained by this method is identical
to that prepared by the direct synthesis, as evidenced by 1H
NMR.
R ea ct ion of (2-Br om op h en yl)lit h iu m w it h Di-ter t-
bu tyld ich lor osta n n a n e. A solution of 1,2-dibromobenzene
(1.19 mL, 10.0 mmol) in THF (7 mL) and diethyl ether (7 mL)
was allowed to react with n-butyllithium (1.50 M in hexane,
6.73 mL, 10.1 mmol) at -110 °C. The resulting mixture was
stirred for 1 h at this temperature. Addition of di-tert-
butyldichlorostannane (1.550 g, 5.10 mmol) in THF (3 mL) and
ether (3 mL) at -110 °C followed. After the mixture had
warmed to room temperature, solvents were removed under
reduced pressure. The residue was subjected to WCC (Al2O3,
hexane) to afford 9,9-di-tert-butyl-9H-tribenzo[b,d,f]stannepin
(3) (248 mg, 16%) and 9,9-di-tert-butyl-9-stannafluorene (4) (79
1
g, 39%). 6: mp 57-59 °C (recrystallization from hexane). H
NMR: δ 1.43(s, 18H), 7.22-7.27(m, 1H), 7.34-7.38(m, 1H),
7.47-7.53(m, 1H), 7.80-7.91(m, 1H). 13C NMR: δ 30.68(q),
30.96(q), 37.84(s), 127.23(d), 129.74(s), 131.08(d), 131.10(d),
139.20(d), 147.06(s). Anal. Calcd for C14H22BrClSn: C, 39.62;
H, 5.23. Found: C, 39.69; H, 5.17.
P r ep a r a tion of 9,9,10,10-Tetr a -ter t-bu tyl-9,10-d ih yd r o-
9,10-d ista n n a a n th r a cen e (5). To a THF (5 mL) solution of
(2-bromophenyl)di-tert-butylchlorostannane (6) (170 mg, 0.40
mmol) was added t-BuLi (1.48 M in pentane, 0.54 mL, 0.80
mmol) at -90 °C. After gradual warming to room temperarure,
aqueous NH4Cl was added to the reaction mixture. The
resulting mixture was extracted with diethyl ether. After
removal of ether, the residue was subjected to WCC (SiO2,
hexane) to afford 9,9,10,10-tetra-tert-butyl-9,10-dihydro-9,10-
distannaanthracene (5) (87 mg, 70%). 5: mp 254-255 °C
(recrystallization from methylene chloride-ethanol, 10:1). 1H
NMR: δ 1.26(s, 36H), 7.24-7.28(m, 4H), 7.52-7.56(m, 4H);
13C NMR: δ 29.75(s), 31.50(q), 127.22(d), 137.75(d), 152.99-

9,10-Dihydro-9,10-distannaanthracenes
Organometallics, Vol. 20, No. 4, 2001 753
(s). Anal. Calcd for C28H44Sn2: C, 54.41; H, 7.18. Found: C,
54.51; H, 7.24.
matrix least-squares refinement was based on 2778 observed
reflections [I > 2.00σ(I)] and 274 variable parameters with
R(Rw) ) 0.043 (0.071).
Cr ysta l a n d Exp er im en ta l Da ta a t 298 K for 2. C14H14
-
Br2Sn2, M ) 460.78, monoclinic, a ) 11.689(1), b ) 11.0470-
(9), c ) 12.3370(8) Å, â ) 104.681(5)°, V ) 1541.1(2) Å3, D )
1.986 Mg m-3, Z ) 4, space group P21/n. The non-hydrogen
atoms were refined anisotropically, and all the hydrogen atoms
were placed at calculated positions (d(C-H) ) 0.96 Å). The
final cycle of full-matrix least-squares refinement was based
on 3121 observed reflections [I > 2.00σ(I)] and 168 variable
parameters with R(Rw) ) 0.066 (0.087).
Cr ysta l a n d Exp er im en ta l Da ta a t 123 K for 5. C28H44-
Sn2, M ) 618.04, triclinic, a ) 10.0710(4), b ) 10.4310(5), c )
14.1980(8) Å, R ) 105.766(2), â ) 92.805(2), γ ) 90.788(2)°, V
) 1433.2(1) Å3, D ) 1.432 Mg m-3, Z ) 2, space group P1h. In
the unit cell, there are two independent halves of each
molecule. The non-hydrogen atoms were refined anisotropi-
cally, and all the hydrogen atoms were placed at calculated
positions (d(C-H) ) 0.96 Å). The final cycle of full-matrix
least-squares refinement was based on 5146 observed reflec-
tions [I > 0.00σ(I)] and 266 variable parameters with R(Rw) )
0.047 (0.103).
Cr ysta l a n d Exp er im en ta l Da ta a t 203 K for 1. C16H20
-
Sn2, M ) 449.76, orthorhombic, a ) 8.8260(6), b ) 15.7350-
(9), c ) 24.503(1) Å, V ) 3402.9(3) Å3, D ) 1.756 Mg m-3, Z )
8, space group P212121. The non-hydrogen atoms were refined
anisotropically, and all the hydrogen atoms were placed at
calculated positions (d(C-H) ) 0.96 Å). The final cycle of full-
matrix least-squares refinement was based on 4269 observed
reflections [I > 2.00σ(I)] and 325 variable parameters with
R(Rw) ) 0.050 (0.066).
Ack n ow led gm en t. This work was partially sup-
ported by a Grant-in-Aid for Encouragement of Young
Scientists No. 10740288 (M.S.) from the Ministry of
Education, Science, Sports, and Culture, J apan.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
data with complete tables of bond lengths, bond angles, and
thermal and positional parameters for 1, 2, 3, and 5. This
material is available free of charge via the Internet at
http://pubs.acs.org.
Cr ysta l a n d Exp er im en ta l Da ta a t 298 K for 3. C26H30
-
Sn, M ) 461.26, orthorhombic, a ) 9.995(2), b ) 23.150(3), c
) 9.607(1) Å, V ) 2223.0(5) Å3, D ) 1.378 Mg m-3, Z ) 4,
space group P212121. The non-hydrogen atoms were refined
anisotropically, and all the hydrogen atoms were placed at
calculated positions (d(C-H) ) 0.96 Å). The final cycle of full-
OM000800I