The first X-ray structure determination of an optically pure bismuthane

Article abstract of DOI:10.1021/om970800r

(4-Chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl} iodobismuthane (3b), the first example of an optically pure bismuthane, was synthesized with exclusive stereoselectivity using Bi-N intramolecular coordination and the planar chirality of ferrocene. The variable-temperature ¹H NMR spectra measured in the range from -50 to +50 °C in CDCl₃ revealed that no epimerization takes place at the bismuth center. An X-ray crystallographic study demonstrated that the bismuth atom is diastereoselectively introduced into the substituted cyclopentadienyl ring and that the 4-chlorophenyl group occupies the exo position toward the iron atom. The absolute configuration around the bismuth atom was determined to be R. The longer intramolecular Bi-N distance of 3b [2.71(1) A?] compared with those of chloro{2-[(R)-1-(dimethylamino)ethyl]phenyl}phenylbismuthane (1a,b) [2.55(2), 2.57(2) A?, respectively] indicates a weaker Bi-N coordination in the ferrocene system. The specific rotation of 3b, [α]D²³ -546 (c 1.0, CHC1₃), is negatively much larger than that of bis(4-chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}bismuthane (5b), [α]D²³ -330 (c 1.0, CHCl₃), which is considered to be the result of generation of the optically active center at bismuth.

Full text of DOI:10.1021/om970800r

Organometallics 1998, 17, 1711-1715
1711
Th e F ir st X-r a y Str u ctu r e Deter m in a tion of a n Op tica lly
P u r e Bism u th a n e
Toshihiro Murafuji,* Kohichi Satoh, and Yoshikazu Sugihara*
Department of Chemistry, Faculty of Science, Yamaguchi University, Yoshida,
Yamaguchi 753-8512, J apan
Nagao Azuma
Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, J apan
Received September 11, 1997
(4-Chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}iodobismuthane (3b), the
first example of an optically pure bismuthane, was synthesized with exclusive stereoselec-
tivity using Bi-N intramolecular coordination and the planar chirality of ferrocene. The
1
variable-temperature H NMR spectra measured in the range from -50 to +50 °C in CDCl3
revealed that no epimerization takes place at the bismuth center. An X-ray crystallographic
study demonstrated that the bismuth atom is diastereoselectively introduced into the
substituted cyclopentadienyl ring and that the 4-chlorophenyl group occupies the exo position
toward the iron atom. The absolute configuration around the bismuth atom was determined
to be R. The longer intramolecular Bi-N distance of 3b [2.71(1) Å] compared with those of
chloro{2-[(R)-1-(dimethylamino)ethyl]phenyl}phenylbismuthane (1a ,b) [2.55(2), 2.57(2) Å,
respectively] indicates a weaker Bi-N coordination in the ferrocene system. The specific
23
rotation of 3b, [R]D -546 (c 1.0, CHCl3), is negatively much larger than that of
23
bis(4-chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]ferrocenyl}bismuthane (5b), [R]D
-330 (c 1.0, CHCl3), which is considered to be the result of generation of the optically active
center at bismuth.
In tr od u ction
mixture of chlorobismuthane 1 (a :b ) 77:23 in CDCl3)
by asymmetric induction at a bismuth atom using the
(R)-1-(dimethylamino)ethyl group as an auxiliary chiral
ligand,5 the optical resolution was unsuccessful due to
cis/trans pairing crystals in ratio of 1:1.6 In our
preliminary communication,7 we reported an efficient
methodology for inducing exclusive stereocontrol over
a chiral bismuth center by using Bi-N intramolecular
coordination and the planar chirality of ferrocene. Thus,
the relatively small C-Bi-C bond angle (∼93°) en-
hances the repulsive interaction between the endo
aromatic substituent and the ferrocene moiety, so that
the exo isomer 2 is formed exclusively (Scheme 1).
The methodology is useful for the stereoselective
synthesis of optically pure bismuthanes. We describe
here the stereoselective synthesis, X-ray crystallo-
graphic study and behavior in solution of enantiomeri-
cally pure 3b.
Construction of optically active heteroatom centers
has attracted much interest in main group chemistry.1
Although a number of compounds bearing such a center
of the group 15 elements have been studied, the
research has been limited to examples of phosphorus,2
arsenic,3 and antimony.4 Bismuth occupies the last row
of this group and is the heaviest stable element in
nature; thus extension of such studies to compounds of
bismuth is of interest. The paucity of such organobis-
muth compounds is most likely due to the lack of
suitable methods for their preparation. Although we
have succeeded in the synthesis of a diastereomeric
(1) (a) For boron: Shiner, C. S.; Garner, C. M.; Haltiwanger, R. C.
J . Am. Chem. Soc. 1985, 107, 7167. (b) For silicon: Sommer, L. H.;
Frye, C. L.; Parker, G. A.; Michael, K. W. J . Am. Chem. Soc. 1964, 86,
3271. (c) For tin: J astrzebski, J . T. B. H.; Boersma, J .; van Koten, G.
J . Organomet. Chem. 1991, 413, 43. (d) For selenium: Kamigata, N.;
Nakamura, Y.; Kikuchi, K.; Ikemoto, I.; Shimizu, T.; Matsuyama, H.
J . Chem. Soc., Perkin Trans. 1 1992, 1721. (e) For tellurium: Kami-
gata, N.; Matsuhisa, A.; Taka, H.; Shimizu, T. J . Chem. Soc., Perkin
Trans. 1 1995, 821.
(2) (a) Naumann, K.; Zon, G.; Mislow, K. J . Am. Chem. Soc. 1969,
91, 7012. (b) Korpiun, O.; Lewis, R. A.; Chickos, J .; Mislow, K. J . Am.
Chem. Soc. 1968, 90, 4842. (c) Horner, L.; Schedlbauer, F.; Beck, P.
Tetrahedron Lett. 1964, 1421.
Resu lts a n d Discu ssion
Compound 2 as prepared is a mixture of enantiomers
because the bismuth is not introduced selectively into
(5) Suzuki, H.; Murafuji, T.; Matano, Y.; Azuma, N. J . Chem. Soc.,
Perkin Trans. 1 1993, 2969.
(3) Campbell, I. G. M.; Poller, R. C. J . Chem. Soc. 1956, 1195.
(4) (a) Campbell, I. G. M.; Morrill, D. J . J . Chem. Soc. 1955, 1662.
(b) Campbell, I. G. M. J . Chem. Soc. 1952, 4448. (c) Campbell, I. G. M.
J . Chem. Soc. 1950, 3109.
(6) Murafuji, T.; Azuma, N.; Suzuki, H. Organometallics 1995, 14,
1542.
(7) Murafuji, T.; Mutoh, T.; Sugihara, Y. J . Chem. Soc., Chem.
Commun. 1996, 1693.
S0276-7333(97)00800-5 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 04/04/1998

1712 Organometallics, Vol. 17, No. 9, 1998
Murafuji et al.
Sch em e 1
ring is observed at a markedly downfield region (δ 4.85).
Unlike 4a , the proton signals of the CH2 and Me2N
groups in 3a appeared at ambient temperature as sharp
AB doublets and a very broad singlet, respectively. At
-50 °C in CDCl3, the latter signal split into two sharp
singlets, which coalesced at 20 °C. At this coalescence
temperature, the proton signals of the Me2N group in
the benzene analogue of 3a , that is, chloro(4-chlorophen-
yl){2-[(dimethylamino)methyl]phenyl}bismuthane, re-
mained as two sharp singlets. These findings indicate
that the nitrogen atom coordinates weakly with the
bismuth atom in 3a and that the dissociation-regen-
eration of the Bi-N bond together with concomitant
vertex inversion at the nitrogen atom and rotation about
the CH2-N bond of 180° takes place at the coalescence
temperature.
Optically pure iodobismuthane 3b could be obtained
in 35% overall yield as a single diastereomer by a
method similar to that used for 3a using diastereose-
lective ortholithiation.8 The proton signals of the Me2N
group were observed at ambient temperature as two
very broad singlets. The variable-temperature 1H NMR
spectra of 3b measured in the range from -50 to +50
°C in CDCl3 showed a trend similar to that observed in
3a . Namely, the proton signals of the Me2N group
appeared at -50 °C as two sharp singlets. The coales-
cence temperature was 40 °C, which is higher than that
of 3a . Activation parameters (∆Gq, ∆Hq, ∆Sq) for this
process were estimated to be 13.5 kcal mol-1, 17.5 kcal
Sch em e 2
mol-1, and 13.8 cal mol-1 deg-1 and 14.2 kcal mol-1
,
16.0 kcal mol-1, and 5.7 cal mol-1 deg-1, respectively,
for 3a and 3b. It should be pointed out that the proton
signals of the unsubstituted cyclopentadienyl ring showed
essentially no shift even above the coalescence temper-
ature. This indicates that the 4-chlorophenyl group is
fixed toward the exo side and no epimerization takes
place at the bismuth center.
A single-crystal X-ray crystallographic study revealed
the stereochemistry at the chiral bismuth center of 3b
(Figure 1). Namely, the bismuth atom is diastereose-
lectively introduced into the substituted cyclopentadi-
enyl ring, and furthermore, the 4-chlorophenyl group
occupies an exo position toward the iron atom. The
absolute configuration around the bismuth atom was
determined to be R in accordance with the rule intro-
duced by Martin in the case of optically active sul-
furanes.10 The bismuth center has a distorted pseudo-
trigonal bipyramidal configuration, where the carbon
atoms C(1) and C(7) occupy an equatorial plane with a
C(1)-Bi(1)-C(7) angle of 95.8(5)° (Table 2). The apical
positions of the pseudotrigonal bipyramid are occupied
by the nitrogen and iodine atoms with a N(1)-Bi(1)-
I(1) angle of 161.4(2)°. The lone pair of electrons is
considered to occupy the remaining equatorial position.
The intramolecular Bi(1)-N(1) distance, 2.71(1) Å, is
longer than the sum of the covalent radii (2.14 Å) but
is much shorter than the sum of the van der Waals radii
(3.66 Å).5 In addition, the Bi(1)-I(1) bond length,
2.969(1) Å, is longer than the sum of the covalent radii
(2.72 Å).11 These observations support the formation
of a Bi-N intramolecular coordination bond. The longer
one of the ortho positions in the substituted cyclopen-
tadienyl ring.7 If the coordinative imino group of 2 is
replaced by the (R)-1-(dimethylamino)ethyl group, opti-
cally pure 3b should form predominantly as a single
diastereomer since bismuth can be introduced selec-
tively into one of the ortho positions in the substituted
cyclopentadienyl ring by using diastereoselective
ortholithiation.8 Initially, we examined the synthesis
of iodobismuthane 3a prior to 3b to confirm the stereo-
control over a chiral bismuth center and the stability
(Scheme 2).9 As expected, 3a was obtained in 30%
overall yield as a single and stable diastereomer, where
the 4-chlorophenyl group lies exo to the iron and a Bi-N
intramolecular coordination bond forms. Thus, the
proton signals of the unsubstituted cyclopentadienyl
ring do not suffer from any upfield shift by the ring
current of the 4-chlorophenyl group.7 Furthermore, the
one-proton signal of the substituted cyclopentadienyl
(8) For diastereoselective ortholithiation of 4b, see: Marquarding,
D.; Klusacek, H.; Gokel, G.; Hoffmann, P.; Ugi, I. J . Am. Chem. Soc.
1970, 92, 5389.
(10) Martin, J . C.; Balthazor, T. M. J . Am. Chem. Soc. 1977, 99,
(9) For ortholithiation of 4a , see: Slocum, D. W.; Rockett, B. W.;
Hauser, C. R. J . Am. Chem. Soc. 1965, 87, 1241.
152.
(11) Bondi, A. J . Phys. Chem. 1964, 68, 441.

X-ray Structure Determination of Bismuthane
Organometallics, Vol. 17, No. 9, 1998 1713
Ta ble 1. Cr ysta l a n d Str u ctu r e Deter m in a tion
Da ta for 3b
formula
fw
C20H22BiClFeIN
703.59
temp, K
298
a, Å
b, Å
11.147(5)
20.402(4)
9.417(2)
c, Å
V, Å3
2142(1)
crystal color and shape
crystal system
space group
Z
red-brown and plate
orthorhombic
P212121
4
F(000)
D
1312
2.182
calcd, g cm-3
crystal dimensions, mm
λ, Å (graphite-monochromated Mo KR)
diffractometer
0.35 × 0.30 × 0.15
0.710 69
Rigaku AFC5R
104.17
2θmax ) 55°
ω-2θ
16.0
0.84 + 0.30 tan θ
2824
2013 [I > 3.00σ(I)]
227
µ, cm-1
collection range
scan type
scan rate, deg min-1
scan width, deg
no. of unique reflections
no. of observed data
no. of variables
range of transmission factors
0.43-1.00
Ra
0.038
a
Rw
0.035
maximum peak in final Fourier map, e Å-3 1.53
minimum peak in final Fourier map, e Å-3 -1.55
goodness of fit
1.28
a
2
R ) ∑||Fo| - |Fc||/∑|Fo|, Rw ) [∑w(|Fo| - |Fc|)2/∑wFo
]
1/2; w )
1/σ2(Fo) ) 4Fo2/σ2(Fo2).
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 3b, w ith Esd ’s in P a r en th eses
Bond Lengths
Bi(1)-N(1)
Bi(1)-C(7)
2.71(1) Bi(1)-C(1)
2.19(1) Bi(1)-I(1)
2.24(1)
2.969(1)
Bond Angles
N(1)-Bi(1)-I(1)
C(1)-Bi(1)-I(1)
N(1)-C(12)-C(8)
161.4(2)
89.1(3)
107(1)
C(1)-Bi(1)-C(7)
95.8(5)
92.1(3)
C(7)-Bi(1)-I(1)
F igu r e 1. ORTEP drawing of a molecular structure of 3b.
- indicates 50% probability of ellipsoids.
Bi(1)-C(7)-C(8) 119(1)
Bi(1)-C(7)-C(11) 135(1)
Bi-N distance of 3b compared with those of 1a ,b
[2.55(2) and 2.57(2) Å, respectively]6 is ascribable to the
large angles constituted by the vicinal substituents of
the cyclopentadienyl ring, indicating a weaker Bi-N
coordination in the ferrocene system. The intermolecu-
lar Bi(1)-I(1) distance of 3b, 3.990(1) Å, which is within
the sum of the van der Waals radii (4.24 Å),11 suggests
the interaction between these atoms.
lectivity by using Bi-N intramolecular coordination and
the planar chirality of ferrocene. This strategy may
serve as a guide for inducing stereocontrol over other
heteroatom centers.
Exp er im en ta l Section
Gen er a l Com m en ts. All reactions were carried out under
argon. Diethyl ether and dichloromethane were distilled from
calcium hydride under nitrogen before use. Bismuth(III)
chloride was purified by refluxing with thionyl chloride. 1H
and 13C NMR spectra were recorded in CDCl3 on a Hitachi
R-250H (250 MHz) and J EOL EX-400 (400 MHz) spectrometer,
respectively, with tetramethylsilane as an internal standard.
Variable-temperature 1H NMR spectra were measured in
CDCl3 on a J EOL GSX-400 (400 MHz). IR spectra were
obtained as KBr pellets on a Nicolet Impact 410 spectropho-
tometer. Optical rotations were taken with HORIBA SEPA-
200.
exo-[2-(N -Be n zylfor m im id oyl)fe r r oce n yl]b r om o(4-
m eth ylp h en yl)bism u th a n e (2a ). Chlorobis(4-methylphen-
yl)bismuthane (∼3 mmol) was generated by stirring tris(4-
methylphenyl)bismuthane (964 mg, 2 mmol) and bismuth(III)
chloride (315 mg, 1 mmol) in diethyl ether (10 mL) for 1 h at
room temperature. To a solution of lithiated N,N,N′-trimeth-
ylethylenediamine (∼4 mmol) prepared from N,N,N′-trimeth-
ylethylenediamine (0.51 mL, 4 mmol) and n-butyllithium (4
Optically active 3b has three different stereogenic
23
centers within this molecule. The specific rotation [R]D
is -546 (c 1.0, CHCl3), which is negatively much larger
than those of 4b, [R]D +14.1 (c 1.6, EtOH),12 and 5b,
24
23
[R]D -330 (c 1.0, CHCl3). The specific rotation of 5b
is comparable to that of compound 6, the phosphorus
25
homologue of 5b, [R]D -361 (c 0.6, CHCl3).12 If the
molecular weights of 4b, 5b, and 3b are taken into
account, molecular rotations [M]D of these compounds
are calculated at +36, -2270, and -3842, respectively.
Such a large difference in the values between 3b and
5b is considered to arise from the generation of the
stereogenic center at bismuth.
In conclusion, an optically pure bismuthane was
synthesized for the first time with exclusive stereose-
(12) Hayashi, T.; Mise, T.; Fukushima, M.; Kagotani, M.; Na-
gashima, N.; Hamada, Y.; Matsumoto, A.; Kawakami, S.; Konishi, M.;
Yamamoto, K.; Kumada, M. Bull. Chem. Soc. J pn. 1980, 53, 1138.

1714 Organometallics, Vol. 17, No. 9, 1998
Murafuji et al.
mmol) in diethyl ether (10 mL) was added at ice bath
temperature formylferrocene (428 mg, 2 mmol) followed after
15 min by chlorotrimethylsilane (0.25 mL, 2 mmol), and the
mixture was stirred for 1 h at room temperature. Then, tert-
butyllithium (4 mmol) was added dropwise at -78 °C and the
temperature was maintained for 30 min. To the lithium
compound thus obtained was added at this temperature a
suspension of the above chlorobismuthane, and the resulting
mixture was stirred for 15 min, during which time the
temperature was raised to 0 °C. After addition of brine (5 mL),
the mixture was diluted with ethyl acetate (10 mL) and the
insoluble polymeric substances were filtered off. The organic
layer was separated and evaporated under reduced pressure
to leave a brown oil, which was purified by chromatography
on deactivated silica gel (10% water) using benzene as eluent
to afford crude (2-formylferrocenyl)bis(4-methylphenyl)bis-
muthane. To a solution of this bismuthane (204 mg, 0.3 mmol)
in C6H6 (5 mL) was added dropwise at ice bath temperature
boron trifluoride-diethyl etherate until the bismuthane was
consumed (checked by TLC). After addition of benzylamine
(107 mg, 1 mmol), the reaction was quenched by saturated
aqueous NaBr (3 mL) and the organic layer was evaporated
under reduced pressure to afford crude 2a . Recrystallization
from C6H6-hexane (5:1) gave pure product as reddish orange
crystals: yield, 20%; mp 190-192 °C (dec); 1H NMR δ 2.26
(3H, s, Me), 4.25 (5H, s, C5H5), 4.44 (1H, d, J AB ) 14.0 Hz,
CH2), 4.54 (1H, d, J AB ) 14.0 Hz, CH2), 4.67 (1H, m, C5H3),
4.76 (1H, m, C5H3), 5.19 (1H, m, C5H3), 7.15-7.38 (7H, m,
ArH), 7.99 (2H, d, J AB ) 7.3 Hz, MeArH), 8.70 (1H, s, CHN);
IR (cm-1) 1610 (CdN). Anal. Calcd for C25H23BiBrFeN: C,
44.0; H, 3.4; N, 2.05. Found: C, 43.6: H, 3.65; N, 2.1.
ArH), 7.73 (2H, d, J AB ) 7.9 Hz, ArH); IR (cm-1) 1470, 1087,
1007, 803. Anal. Calcd for C25H24BiCl2FeN: C, 44.5; H, 3.6;
N, 2.1. Found: C, 44.3: H, 3.65; N, 2.0.
exo-(4-Ch lor op h e n yl){2-[(d im e t h yla m in o)m e t h yl]-
fer r ocen yl}iod obism u th a n e (3a ). To a solution of 5a (348
mg, 0.5 mmol) in CH2Cl2 (20 mL) was added dropwise at ice
bath temperature boron trifluoride-diethyl etherate until 5a
was consumed (checked by TLC). The reaction was quenched
by the addition of saturated aqueous NaI (3 mL) and the
organic layer was evaporated under reduced pressure to afford
crude 3a . Recrystallization from ethyl acetate gave pure
product as orange crystals: yield, 83%; mp 153-157 °C (dec);
1H NMR δ 2.30 (6H, br s, Me2N), 3.14 (1H, d, J AB ) 14 Hz,
CH2N), 3.76 (1H, d, J AB ) 14 Hz, CH2N), 4.26 (5H, s, C5H5),
4.29 (1H, m, C5H3), 4.48 (1H, m, C5H3), 4.85 (1H, m, C5H3),
7.38 (2H, d, J AB ) 7.9 Hz, ArH), 8.10 (2H, d, J AB ) 7.9 Hz,
ArH); IR (cm-1) 1470, 1004, 830, 812. Anal. Calcd for
C
19H20BiClFeIN: C, 33.1; H, 2.9; N, 2.0. Found: C, 32.9: H,
2.9; N, 2.0.
Bis(4-ch lor oph en yl){(S)-2-[(R)-1-(dim eth ylam in o)eth yl]-
fer r ocen yl}bism u th a n e (5b). Diastereoselective ortholithi-
ation of (R)-(+)-N,N-dimethyl-1-ferrocenylethylamine (4b) was
carried out by modifying the reported procedure.8 To a
solution of 4b (0.51 mL, 2 mmol) in diethyl ether (10 mL) was
added at ice bath temperature tert-butyllithium (2.1 mmol),
and the mixture was stirred at room temperature for 2 h. To
a suspension of the lithium compound thus obtained was added
at ice bath temperature an ethereal suspension of chlorobis-
(4-chlorophenyl)bismuthane (∼2 mmol), and the resulting
mixture was stirred for 15 min. Similar workup as described
for 5a followed by purification by chromatography on silica
gel using hexane-ethyl acetate (5:1) as the eluent afforded
crude 5b. Recrystallization from hexane-ethyl acetate (10:
1) gave pure product as orange crystals: yield, 42%; mp 115-
exo-[2-(N-Ben zylfor m im id oyl)fer r ocen yl]iod o(4-m eth -
ylp h en yl)bism u th a n e (2b). To a solution of (2-formylfer-
rocenyl)bis(4-methylphenyl)bismuthane (204 mg, 0.3 mmol) in
C6H6 (5 mL) was added dropwise at ice bath temperature boron
trifluoride-diethyl etherate until the bismuthane was con-
sumed (checked by TLC). After an addition of benzylamine
(107 mg, 1 mmol), the reaction was quenched by saturated
aqueous NaI (3 mL) and the organic layer was evaporated
under reduced pressure to afford crude 2b. Recrystallization
from C6H6-hexane (5:1) gave pure product as reddish orange
1
116 °C; H NMR δ 1.14 (3H, d, J ) 6.7 Hz, Me), 1.79 (6H, s,
Me2N), 3.89 (1H, m, C5H3), 4.01 (5H, s, C5H5), 4.05 (1H, q, J )
6.7 Hz, MeCH), 4.26 (2H, m, C5H3), 7.26 (2H, d, J AB ) 7.9 Hz,
ArH), 7.33 (2H, d, J AB ) 8.5 Hz, ArH), 7.64 (2H, d, J AB ) 7.9
Hz, ArH), 7.73 (2H, d, J AB ) 8.5 Hz, ArH); IR (cm-1) 1471,
23
1087, 1007, 803. [R]D -330 (c 1.0, CHCl3). Anal. Calcd for
C
26H26BiCl2FeN: C, 45.4; H, 3.8; N, 2.0. Found: C, 45.4: H,
1
crystals: yield, 16%; mp 212-214 °C; H NMR δ 2.27 (3H, s,
4.0; N, 1.9.
Me), 4.25 (5H, s, C5H5), 4.43 (1H, d, J AB ) 14.0 Hz, CH2), 4.53
(1H, d, J AB ) 14.0 Hz, CH2), 4.66 (1H, m, C5H3), 4.71 (1H, m,
C5H3), 5.27 (1H, m, C5H3), 7.16-7.22 (4H, m, ArH), 7.35-7.37
(3H, m, ArH), 8.00 (2H, d, J AB ) 7.9 Hz, MeArH), 8.63 (1H, s,
CHN); IR (cm-1) 1610 (CdN). Anal. Calcd for C25H23BiFeIN:
C, 41.2; H, 3.2; N, 1.9. Found: C, 40.8: H, 3.15; N, 1.95.
exo-(4-Chlorophenyl){(S)-2-[(R)-1-(dimethylamino)ethyl]-
fer r ocen yl}iod obism u th a n e (3b). To a solution of 5b (344
mg, 0.5 mmol) in CH2Cl2 (20 mL) was added dropwise at ice
bath temperature boron trifluoride-diethyl etherate until 5b
was consumed (checked by TLC). The reaction was quenched
by the addition of saturated aqueous NaI (3 mL), and the
organic layer was evaporated under reduced pressure to afford
crude 3b. Recrystallization from ethyl acetate gave pure
product as orange crystals: yield, 83%; mp 176-179 °C (dec);
1H NMR δ 1.13 (3H, d, J ) 6.7 Hz, Me), 1.55 (3H, br s, NMe),
2.55 (3H, br s, NMe), 4.23 (1H, q, J ) 6.7 Hz, MeCH), 4.24
(5H, s, C5H5), 4.32 (1H, m, C5H3), 4.45 (1H, m, C5H3), 4.82 (1H,
B is (4-c h lo r o p h e n y l){2-[(d im e t h y la m in o )m e t h y l]-
fer r ocen yl}bism u th a n e (5a ). Chlorobis(4-chlorophenyl)-
bismuthane (∼2 mmol) was generated by stirring tris(4-
chlorophenyl)bismuthane (723 mg, 1.33 mmol) and bismuth(III)
chloride (211 mg, 0.7 mmol) in diethyl ether (10 mL) for 2 h
at room temperature. To a suspension of ortholithiated [(N,N-
dimethylamino)methyl]ferrocene9 (∼2 mmol) generated from
[(N,N-dimethylamino)methyl]ferrocene (0.4 mL, 2 mmol) and
n-butyllithium (4 mmol) in diethyl ether (5 mL) was added
dropwise at ice bath temperature a suspension of the above
chlorobismuthane, and the resulting mixture was stirred for
15 min. After the addition of brine (5 mL), the mixture was
diluted with ethyl acetate (10 mL) and the insoluble polymeric
substances were filtered. The organic layer was separated and
evaporated under reduced pressure to leave a brown oil, which
was purified by chromatography on silica gel using hexanes-
ethyl acetate (5:1) as the eluent to afford crude 5a . Recrys-
tallization from hexane-ethyl acetate (10:1) gave pure product
as orange crystals: yield, 36%; mp 135-137 °C; 1H NMR
δ 1.92 (6H, s, Me2N), 2.94 (1H, d, J AB ) 12.8 Hz, CH2N), 3.66
(1H, d, J AB ) 12.8 Hz, CH2N), 3.85 (1H, m, C5H3), 4.02 (5H, s,
C5H5), 4.24 (2H, m, C5H3), 7.26 (2H, d, J AB ) 7.9 Hz, ArH),
7.34 (2H, d, J AB ) 7.9 Hz, ArH), 7.65 (2H, d, J AB ) 7.9 Hz,
m, C5H3), 7.38 (2H, d, J AB ) 7.9 Hz, ArH), 8.10 (2H, d, J AB
)
7.9 Hz, ArH); 13C NMR δ 8.2, 37.4(br), 44.3(br), 62.9, 69.9, 70.2,
72.0, 79.8, 99.7, 103.4, 131.0, 134.4, 139.2, 164.1; IR (cm-1
)
23
1090, 1008, 801. [R]D -546 (c 1.0, CHCl3). Anal. Calcd for
C
20H22BiClFeIN: C, 34.1; H, 3.15; N, 2.0. Found: C, 34.1: H,
3.15; N, 2.0.
X-r a y Cr ysta llogr a p h y. All measurements were made on
a Rigaku AFC5R diffractometer with graphite-monochromated
Mo KR radiation and a 12-kW rotating anode generator. The
data were collected at 298 K using the ω-2θ scan technique
to a maximum 2θ value of 55.0°. Scans of (0.84 + 0.30 tan θ)°
were made at a speed of 16.0 deg min-1 (in ω). A total of 2824
unique reflections were collected. The intensities of three
representative reflections measured after every 150 reflections
declined by 0.29%. A linear correction factor was applied to
the data to account for this phenomenon. An empirical
absorption correction, based on azimuthal scans of several

X-ray Structure Determination of Bismuthane
Organometallics, Vol. 17, No. 9, 1998 1715
reflections, was applied which resulted in transmission factors
ranging from 0.43 to 1.00. The data were corrected for Lorentz
and polarization effects. A correction for secondary extinction
was applied (coefficient 1.02 × 10-7). The structure was solved
by the Patterson method.13 The non-hydrogen atoms were
refined anisotropically. The final cycle of full-matrix least-
squares refinement against |F| was based on 2013 observed
reflections [I > 3.00σ (I)] and 227 variable parameters and
converged with unweighted and weighted agreement factors
of R ) 0.038 and Rw ) 0.035. The maximum and minimum
peaks on the final difference Fourier map corresponded to 1.53
and -1.55 e/Å3, respectively. Neutral-atom scattering factors
anomalous dispersion effect was 0.052 for 227 variables and
2013 observations. Inclusion of the anomalous dispersion gave
the Rw factors of 0.0656 and 0.0937 for the present and its
enantiomeric structure, respectively, which yielded the R factor
ratio of 1.43. The corresponding significance point is Rb,
N,
R
) R1, 1786, 0.005 ) 1.002, so that the enantiomeric structure can
be rejected with the probability higher than 99.5%.19
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Developmental Scientific Research
(06554027) from the Ministry of Education, Science and
Culture, J apan. T.M. thanks the Nissan Science Foun-
dation for support of this research.
were taken from Cromer and Waber.14 Anomalous dispersion
15
effects were included in Fcalcd
;
the values for ∆f ′ and ∆f ′′
were those of Cromer.16 All calculations were performed using
the TEXSAN17 crystallographic software package of Molecular
Structure Corp.
Su p p or tin g In for m a tion Ava ila ble: Full details of crys-
tal data, fractional atomic coordinates, bond lengths, bond
angles, hydrogen coordinates, and thermal parameters for 3b
and a unit cell diagram (33 pages). Ordering information is
given on any current masthead page.
The chirality has been examined by the test of the R factor
ratio.18 The Rw factor for the structure refinement without
(13) Calbrese, J . C. PHASE: Patterson Heavy Atom Solution
Extractor. Ph.D. Thesis, University of WisconsinsMadison, 1972.
(14) Cromer, D. T.; Waber, J . T. In International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, England, 1974; Vol.
IV, Table 2.2 A.
(15) Ibers, J . A.; Hamilton, W. C. Acta Crystallogr. 1964, 17, 781.
(16) Cromer, D. T. In International Tables for X-ray Crystallography;
The Kynoch Press: Birmingham, England, 1974; Vol. IV, Table 2. 3.
1.
OM970800R
(17) TEXSAN-TEXRAY Structure Analysis Package, Molecular
Structure Corp., The Woodlands, TX, 1985.
(18) Hamilton, W. C. Acta Crystallogr. 1965, 18, 502.
(19) In International Tables for X-ray Crystallography, Kluwer
Academic Publishers: Dordrecht, The Netherlands, 1989; Vol. 4, p 228.