Synthesis, chemistry, and structures of neopentyl and (trimethylsilyl) methyl antimony and bismuth oligomers

Article abstract of DOI:10.1021/om0301435

Dehalogenation of RSbBr₂ (R = Me₃CCH₂) with Mg gives cyclo-(RSb)_n (n = 4 (1a), 5 (1b)). The compounds cyclo-(RBi)_n (R = Me₃CCH₂; n = 3 (2a), 5 (2b)) form by reaction of RBiCl

Full text of DOI:10.1021/om0301435

Organometallics 2003, 22, 2919-2924
2919
Syn th esis, Ch em istr y, a n d Str u ctu r es of Neop en tyl a n d
(Tr im eth ylsilyl)m eth yl An tim on y a n d Bism u th Oligom er s
Ga´bor Bala´zs, Lucia Bala´zs, Hans J oachim Breunig,* and Enno Lork
Institut fu¨r Anorganische und Physikalische Chemie (Fb 02) der Universita¨t Bremen,
D-28334 Bremen, Germany
Received February 28, 2003
Dehalogenation of RSbBr2 (R ) Me3CCH2) with Mg gives cyclo-(RSb)n (n ) 4 (1a ), 5 (1b)).
The compounds cyclo-(RBi)n (R ) Me3CCH2; n ) 3 (2a ), 5 (2b)) form by reaction of RBiCl2
with LiAlH4. Equilibria between 1a and 1b or between 2a and 2b favor the smaller rings at
higher temperatures and dilution. Thermal reactions of 2a ,b lead to R4Bi2 (3; R ) Me3-
CCH2) and elemental bismuth. Reaction of 2a ,b with W(CO)5(thf) (thf ) tetrahydrofuran)
gives [{µ-η2-cis-(RBi)2}{W(CO)5}2] (4; R ) Me3CCH2). Decomposition of [{µ-η2-cis-(R′Bi)2}-
{W(CO)5}2] (5; R′ ) Me3SiCH2) leads to [η2-trans-(R′Bi)2W(CO)5] (6). The crystal structures
of 1b, 4, and 6 are reported.
In tr od u ction
methyl and neopentyl compounds (RE)n (E ) Sb, Bi; R
) Me3SiCH2, Me3CCH2) for comparative studies where
also aspects of the coordination chemistry of these rings
were included. Our previous work showed that the
(trimethylsilyl)methyl antimony ring system exists in
benzene at ambient temperature mainly as the pen-
tamer, (Me3SiCH2Sb)5, and a small fraction of the
corresponding tetramer.9 X-ray diffraction studies re-
vealed that crystals contain exclusively the pentamer,
although a full determination of the structure failed due
to disorder. The reaction of the (trimethylsilyl)methyl
antimony rings with W(CO)5(thf) in the 1:3 molar ratio
results in the coordination of the pentamer in 1,3-
[W(CO)5]2(Me3SiCH2Sb)5.10 The analogous bismuth ring
system (RBi)n (R ) Me3SiCH2; n ) 3, 5) is essentially a
trimer-pentamer equilibrium in benzene or toluene in
the range from -15 to +35 °C, and the reaction with
W(CO)5(thf) gives [{µ-η2-cis-(RBi)2}{W(CO)5}2] (5; R )
Me3SiCH2 (5)), a complex with a cis-dibismuthene
ligand.6 The present report features cyclostibines (1),
cyclobismuthines (2), a dibismuthine (3), and dibis-
muthene complexes (4-6) with neopentyl and trimeth-
ylsilylmethyl substituents.
Relativistic effects1 should lead to fundamental dif-
ferences between the reactivity of bismuth(I) compounds
and analogous compounds of antimony or the lighter
group 15 elements. While true inorganic Bi(I) com-
pounds are still very rare, a number of organometallic
examples, e.g. trans-dibismuthenes, RBidBiR (R )
2,4,6-[(Me3Si)2CH]3C6H2, 2,6-(Me3C6H2)2C6H3),2,3 and
cyclobismuthines, (RBi)n (n ) 3-5; R ) (Me3Si)2CH,4
(Me3Si)3Si,5 Me3SiCH26), were recently described and
comparison with analogous compounds of the lighter
elements has become possible. We found that the
bismuth compounds (RBi)n (R ) (Me3Si)2CH; n ) 3, 4)
exist in solution in a ring-ring equilibrium between the
cis,trans trimer and the all-trans tetramer.4 The analog-
ous cyclostibines have similar structures but different
chemistry. They are not transformable into each other
in a thermal equilibrium. The tetramer (RSb)4 (R )
(Me3Si)2CH) is stable up to 160 °C.7 The transformation
into the corresponding trimer, (RSb)3, was observed only
in an irreversible photochemical reaction.8 Assuming
that in sterically less hindered ring systems the specific
properties of analogous Sb(I) and Bi(I) compounds might
emerge even more clearly, we chose the (trimethylsilyl)-
Resu lts a n d Discu ssion
* To whom correspondence should be addressed. E-mail: breunig@
chemie.uni-bremen.de. Fax: 49 421 218 4042.
(1) Pyykko¨, P. Chem. Rev. 1988, 88, 563.
The reaction of Me3CCH2SbBr2 with Mg in thf gives
cyclo-(Me3CCH2Sb)n (n ) 4 (1a ), 5 (1b)) in 61% yield
(Scheme 1). The novel antimony rings are yellow
crystalline solids, readily soluble in hydrocarbons and
stable under an inert atmosphere for a long time. They
were identified by the observation of the molecular ions
in the mass spectra, by elemental analyses, by NMR
spectra, and by a single-crystal X-ray diffraction study
(2) (a) Tokitoh, N.; Arai, Y.; Okazaki, R.; Nagase, S. Science 1997,
277, 78. (b) Tokitoh, N.; Arai, Y.; Okazaki, R. Phosphorus, Sulfur
Silicon Relat. Elem. 1997, 371, 124. (c) Tokitoh, N. J . Organomet.
Chem. 2000, 611, 217. (d) Sasamori, T.; Takeda, N.; Tokitoh, N. Chem.
Commun. 2000, 1353.
(3) (a) Twamley, B.; Sofield, C. D.; Olmstead, M. M.; Power, P. P. J .
Am. Chem. Soc. 1999, 121, 3357. (b) Power, P. P. Chem. Rev. 1999,
99, 3463.
(4) (a) Breunig, H. J .; Ro¨sler, R.; Lork, E. Angew. Chem. 1998, 110,
3361; Angew. Chem., Int. Ed. 1998, 37, 3175. (b) Breunig, H. J .; Ro¨sler,
R. Chem. Soc. Rev. 2000, 29, 403.
(5) Linti, G.; Ko¨stler, W. Z. Anorg. Allg. Chem. 2002, 628, 63.
(6) Bala´zs, L.; Breunig, H. J .; Lork, E. Angew. Chem. 2002, 13, 2411;
Angew. Chem., Int. Ed. 2002, 41, 2309.
1
of the five-membered-ring compound 1b. The H NMR
spectra of 1a ,b in C6D6 at room temperature are
depicted in Figure 1.
(7) Ates, M.; Breunig, H. J .; Ebert, K.; Gu¨lec, S.; Kaller, R.; Dra¨ger,
M. Organometallics 1992, 11, 145.
(8) Breunig, H. J .; Ro¨sler, R.; Lork, E. Organometallics 1998, 17,
5594.
(9) Silvestru, A.; Breunig, H. J .; Ebert, K. H.; Kaller, R. J . Organ-
omet. Chem. 1995, 501, 117.
(10) Bala´zs, G.; Breunig, H. J .; Lork, E. Z. Anorg. Allg. Chem. 2001,
627, 2666.
10.1021/om0301435 CCC: $25.00 © 2003 American Chemical Society
Publication on Web 05/31/2003

2920 Organometallics, Vol. 22, No. 14, 2003
Bala´zs et al.
F igu r e 1. 1H NMR spectra (200 MHz) of ([) (Me3CCH2-
Sb)4 (1a ) and (f) (Me3CCH2Sb)5 (1b) in C6D6 at room
temperature.
F igu r e 2. (left) Structure of (Me3CCH2Sb)5 (1b) in the
crystal state. The ellipsoids represent 25% probability.
(right) conformation of the Sb core in 1b. Selected bond
lengths (Å) and angles (deg): Sb(1)-Sb(5) ) 2.812(3),
Sb(1)-Sb(2) ) 2.818(3), Sb(2)-Sb(3) ) 2.819(3), Sb(3)-
Sb(4) ) 2.82(3), Sb(4)-Sb(5) ) 2.818(3), Sb(1)-C(1) )
2.17(2), Sb(2)-C(2) ) 2.25(3), Sb(3)-C(3) ) 2.20(2), Sb(4)-
C(4) ) 2.16(3), Sb(5)-C(5) ) 2.21(3); Sb(1)-Sb(2)-Sb(3)
) 102.4(1), Sb(5)-Sb(1)-Sb(2) ) 103.9(1), Sb(2)-Sb(3)-
Sb(4) ) 97.3(1), Sb(5)-Sb(4)-Sb(3) ) 95.9(1), Sb(1)-Sb(5)-
Sb(4) ) 103.3(1), C(1)-Sb(1)-Sb(5) ) 97.2(6), C(1)-Sb(1)-
Sb(2) ) 95.5(7), C(2)-Sb(2)-Sb(1) ) 96.5(7), C(2)-Sb(2)-
Sb(3) ) 93.6(7), C(3)-Sb(3)-Sb(2) ) 94.3(9), C(3)-Sb(3)-
Sb(4) ) 92.2(7), C(4)-Sb(4)-Sb(5) ) 99.0(1), C(4)-Sb(4)-
Sb(3) ) 98.4(9), C(5)-Sb(5)-Sb(1) ) 88.8(6), C(5)-Sb(5)-
Sb(4) ) 97.9(8), Sb(1)-Sb(5)-Sb(4) ) 103.3(1).
Sch em e 1
2.812(3) to 2.820(3) Å. They lie in the usual region for
Sb-Sb single-bond lengths in cyclostibines (R4Sb4 at
2.822(1)-2.878(1) Å7 and R3Sb3 at 2.8188(6)-2.8453(6)
Å,8 R ) (Me3Si)2CH; 1,3-[W(CO)5]2(Me3SiCH2Sb)5 at
2.818(1)-2.842(1) Å10). The Sb-Sb-Sb angles in 1b fall
in two groups; two are narrow (97.3(1) and 95.9(1)° at
Sb(3) and Sb(4)) and three are wide (102.4(1), 103.3(1),
and 103.9(1)° at Sb(1), Sb(2), and Sb(5)). The Sb-C bond
lengths (2.16(3)-2.25(3) Å) and Sb-Sb-C angles
(88.8(6)-99.0(1)°) are not unusual. A remarkable fea-
ture of the crystal structure of 1b is the zigzag chain
association of the stibolane molecules with intermolecu-
lar Sb(3)‚‚‚Sb(4) contact distances of 4.22 Å, which are
close to the sum of van der Waals radii of two Sb atoms
(4.4 Å). These weak contacts may be responsible for the
avoidance of disorder phenomena, which affected our
attempts to determine the structures of (Me3SiCH2Sb)5
and 2b. Close intermolecular Sb‚‚‚Sb contacts were
observed before in the stacks of the (PhSb)6‚(solvate)
species (4.18-4.23 Å),12 in the chains of (MesSb)4‚
(benzene) (3.88 Å),13 and in distibines, R2SbSbR2.14
Views of the chain association in the crystal structure
of 1b are presented in Figure 3.
The spectra contain two singlet signals, one for the
CH3 and one for the CH2 protons of the antimony four-
membered ring 1a in the all-trans configuration, and
three singlet signals in a 2:1:2 intensity ratio for the
CH3 groups as well as a singlet and eight signals of two
AB spin systems for the CH2 groups of the five-
membered-ring species 1b, where the neopentyl groups
adopt a maximum of trans positions. The fraction of 1a
increases at the cost of 1b on dilution in a ring-ring
equilibrium (Scheme 1) with the equilibrium constant
[1b]4/[1a ]5 ) 1.38 × 1011 L mol-1 for an overall concen-
tration, [1a ] + [1b], of 2.22 × 10-6 mol L-1. Even at
high dilution no signals for a trimer are visible. Char-
acteristic signals for 1a ,b are also observed in the 13C
NMR spectra. Yellow crystals of 1b were grown from a
solution in petroleum ether at -28 °C, and the structure
was determined by X-ray diffraction. The crystals
consist of cyclo-(Me3CCH2Sb)5 molecules. The conforma-
tion of the antimony five-membered ring is close to an
envelope structure where Sb(1), Sb(2), Sb(3), and Sb(5)
lie almost in a plane (mean deviation 0.1690 Å) and
Sb(4) is 1.5291 Å above this plane (Figure 2).
The synthesis of the neopentyl bismuth rings, cyclo-
(Me3CCH2Bi)n (n ) 3 (2a ), 5 (2b)) is achieved by the
reaction of Me3CCH2BiCl2 with LiAlH4 in Et2O at -70
°C and decomposition of the intermediate product, Me3-
CCH2BiH2, at about -50 °C (Scheme 2).
The Sb(5)-Sb(1)-Sb(2)-Sb(3) and Sb(2)-Sb(1)-
Sb(5)-Sb(4) torsion angles are 18.2(1) and 19.0(1)°,
respectively. Two of the neopentyl groups are cis to each
other, and three groups are trans to their neighbors.
1b is the first five-membered organoantimony mono-
cycle (pentastibolane) to be fully characterized by crystal
structure analysis. The closest related compounds with
known crystal structures are 1,3-[W(CO)5]2(Me3SiCH2-
The bismuth rings 2a ,b are air sensitive and ther-
mally unstable in solution. Removal of the solvent at
(12) Breunig, H. J .; Soltani-Neshan, A.; Ha¨berle, K.; Dra¨ger, M. Z.
Naturforsch. 1986, 41b, 327.
(13) Ates, M.; Breunig, H. J .; Gu¨lec, S.; Offermann, W.; Ha¨berle,
K.; Dra¨ger, M. Chem. Ber. 1989, 122, 473.
(14) (a) Ashe, A. J . III, Adv. Organomet. Chem. 1990, 30, 77. (b)
Breunig, H. J . In The Chemistry of Organic Arsenic, Antimony and
Bismuth Compounds; Patai, S., Ed.; Wiley: Chichester, U.K., 1994; p
441.
Sb)5 and (Me3SiCH2As)5,11 two five-membered rings
10
which adopt envelope conformations. The Sb-Sb bond
lengths in 1b are very homogeneous, ranging from
(11) Wells, R. L.; Kwag, C.-Y.; Purdy, A. P.; McPhail, A. T.; Pitt, C.
G. Polyhedron 1990, 9, 319.

Neopentyl and (Me3Si)CH2 Sb and Bi Oligomers
Organometallics, Vol. 22, No. 14, 2003 2921
Sch em e 3
signals are observed in the methylene region. Like 1b,
2b also exists in solution in the configuration with a
maximum of trans positions of the substituents with
ring inversion between the conformers leading to an
effective plane of symmetry. Two additional singlet
signals of low intensity result probably from cyclo-
(RBi)4. When a solution in C6D5CD3 is cooled, the signals
of the five-membered-ring compound 2b increase in
intensity at the cost of those of the three-membered-
ring species 2a and the accidental isochronism in the
spectrum of 2b is abolished. The ring-ring reactions
(Scheme 3) are fully reversible between -20 and 20 °C.
Below -20 °C the equilibrium is frozen with a 2a :2b
molar ratio of 0.3:1. At 45 °C the 2a :2b ratio is 2:1;
however, rapid decomposition occurs at this tempera-
ture. The values for the equilibrium constant K ) [2a ]5/
[2b]3 are K ) 2.12 × 10-3 mol2 L-2 at 20 °C for an overall
concentration, [2a ] + [2b], of 1.8 × 10-1 mol L-1 and K
) 2.7 × 10-4 mol2 L-2 at -20 °C for an overall
F igu r e 3. View of the chain association in the crystal
structure of (Me3CCH2Sb)5 (1b).
concentration, [2a ] + [2b], of 2.2 × 10-1 mol L-1
.
The red solid obtained by evaporation of the solvent
contains probably all the rings with 2b as the most
abundant species. Single crystals grow in acetone at -28
°C. An X-ray structure analysis revealed the exclusive
presence of the five-membered-ring species 2b. How-
ever, a full determination of the structure was prevented
by disorder phenomena resulting probably from ir-
regular orientations of the five-membered rings.
F igu r e 4. 1H NMR spectra (200 MHz) of (x) (Me3CCH2-
Bi)5 (2a ), (o) (Me3CCH2Bi)3 (2b), and (*) (Me3CCH2Bi)4 in
C6H5CD3.
Thermal decomposition of 2a ,b gives the dibismuthine
3 in 60% yield and elemental bismuth (eq 1). 3 is an
Sch em e 2
(4/n)cyclo-(RBi)n
R Bi-BiR
f
+ 2Bi
2
(1)
2
2
3
R ) Me3CCH2; n ) 3, 5
1
orange air-sensitive solid, soluble in hydrocarbons. H
NMR spectra show four signals of an AB spin system
and a singlet for the CH2 and CH3 protons. The identity
of 3 was also proven by elemental analyses and mass
spectra containing the molecular ion.
The reaction of 2a ,b with W(CO)5(thf) gives [{µ-η2-
cis-(Me3CCH2Bi)2}{W(CO)5}2] (4) (eq 2). 4 is a light red
reduced pressure gives a dark red amorphous solid,
which is self-igniting in air but stable for months at
room temperature under an inert atmosphere. 1H NMR
spectra of solutions of 2a ,b are shown in Figure 4. The
spectra in C6D6 and C6D5CD3 at 20 °C contain two
singlet signals in a 1:2 ratio of intensities for the CH3
groups as well as four signals of an AB spin system and
a singlet for the CH2 groups of the bismuth three-
membered-ring system 2a in the cis,trans configuration.
For the bismuth five-membered-ring compound 2b there
is a complex multiplet signal for the methyl groups. The
signals of one of the two diastereotopic CH2 groups of
2b are isochronic at 20 °C, and therefore, instead of two
systems, only one AB spin system and two singlet
(2/n)cyclo-(RBi)n + 2W(CO)5(thf) -2thf8
2
(RBi)2[W(CO)5]2 (2)
4
R ) Me3CCH2; n ) 3, 5
crystalline solid, soluble in organic solvents. Crystals
1
and solutions are air sensitive. H NMR spectra of 4
contain two singlet signals: one for the CH3 and the
other for the CH2 groups. The fragment M - R appears
at th e highest mass in the mass spectra. The composi-
tion was confirmed by high-resolution mass spectro-

2922 Organometallics, Vol. 22, No. 14, 2003
Bala´zs et al.
F igu r e 5. Structure of (Me3CCH2Bi)2[W(CO)5]2 (4) in the
crystal state. The ellipsoids represent 30% probability.
Selected distances (Å) and angles (deg): Bi(1)-Bi(1′) )
2.9799(7), Bi(1)-C(1) ) 2.312(7); Bi(1)-W(1) ) 3.1288(7),
Bi(1)-W(2) ) 3.1411(7); C(1)-Bi(1)-Bi(1′) ) 94.5(2), C(1)-
Bi(1)-W(1) ) 102.8(2), Bi(1′)-Bi(1)-W(1) ) 61.6(1), C(1)-
Bi(1)-W(2) ) 103.8(2), Bi(1′)-Bi(1)-W(2) ) 61.7(1), W(1)-
Bi(1)-W(2) ) 118.2(2).
F igu r e 6. Structure of [(Me3SiCH2Bi)2W(CO)5] (6) in the
crystal state. The ellipsoids represent 40% probability.
Selected distances (Å) and angles (deg): Bi(1)-Bi(2) )
2.8769(5), Bi(1)-C(1) ) 2.284(6), Bi(2)-C(2) ) 2.295(6),
Bi(1)-W(1) ) 3.0701(9), Bi(2)-W(1) ) 3.0792(6); C(1)-
Bi(1)-Bi(2) ) 98.7(2), C(1)-Bi(1)-W(1) ) 99.1(2), C(2)-
Bi(2)-W(1) ) 99.6(2), Bi(2)-Bi(1)-W(1) ) 62.3(2), Bi(1)-
Bi(2)-W(1) ) 62.0(1), C(2)-Bi(2)-Bi(1) ) 95.2(2).
scopy. The analogous complex [{µ-η2-cis-(Me3SiCH2-
Bi)2}{W(CO)5}2] (5) was characterized by elemental
analyses.6
Single crystals of 4 suitable for X-ray diffraction were
grown from a petroleum ether solution at -28 °C. They
belong to the monoclinic space group P21/m. The struc-
ture of 4 consists of a dibismuthene in the cis form in a
bridging position with side-on coordination to two
W(CO)5 fragments (1:2 complex). The torsion angle
C(1)-Bi(1)-Bi(1′)-C(1′) is 0°. The arrangement corre-
sponds to a bicyclic butterfly structure (Figure 5). The
dihedral angles between the Bi2W planes (154.5°) and
the Bi-Bi and Bi-W bond lengths (Bi-Bi ) 2.9799(7)
Å, Bi-W ) 3.1411(7), 3.1288(7) Å) in 4 compare well
with the values found in 5 (Bi-W-Bi ) 155.5°, Bi-Bi
) 3.003(1) Å, Bi-W ) 3.118(1), 3.124(1) Å).6
F igu r e 7. Chain association in the crystal of [(Me3SiCH2-
Bi)2W(CO)5] (6).
Sch em e 4
Both 4 and the analogous Si compound 5 are unstable
in solution at room temperature. For a detailed study
of the solution behavior, we chose 5 and found that
storing a solution of 5 in organic solvents (benzene,
diethyl ether, or petroleum ether) at 20 °C or addition
of Ph3P leads to the removal of a W(CO)5 group and
formation of [(Me3SiCH2Bi)2W(CO)5] (6) (Scheme 4). A
fraction containing crystals of 6 and 5 was obtained by
cooling a solution in petroleum ether to -25 °C. The
composition of 6 was confirmed by high-resolution mass
spectroscopy. A single-crystal X-ray diffraction study
revealed that the structure of solid 6 consists of the
trans isomer of RBidBiR (R ) Me3SiCH2), side-on
coordinated to a W(CO)5 fragment. The molecular
structure is shown in Figure 6. The trans-dibismuthene
ligand is slightly distorted from planarity with a C(1)-
Bi(1)-Bi(2)-C(2) torsion angle of -166.1(2)°.
The Bi-Bi bond in 6 (2.8769(5) Å) is significantly
shorter than in 5 (3.003(1) Å)6 and only slightly longer
than the Bi-Bi double bonds in uncoordinated dibis-
muthenes, RBidBiR (R ) {(Me3Si)2CH}3C6H2, 2.8206(8)
Å;2a R ) (Me3C6H2)2C6H3, 2.832(1) Å3a). Apparently the
double-bond character of the Bi-Bi bond of the dibis-
muthene ligand is essentially preserved in the 1:1
complex 6, whereas bridging coordination to two W(CO)5
groups in 5 leads to considerable reduction of the bond
order. The Bi-W (3.0792(6), 3.0701(9) Å) and Bi-C
(2.284(6), 2.295(6) Å) bond lengths as well as the Bi-
Bi-C (98.7(2), 95.2(2)°) and C-Bi-W (99.1(2), 99.6(2)°)
angles of 6 lie in the usual range. The molecules of 6
are aligned to chains through weak Bi‚‚‚Bi (4.352(1) Å)
contacts which are shorter than the sum of the van der
Waals radii of two bismuth atoms (4.80 Å) (Figure 7).
Chain association through intermolecular Bi‚‚‚Bi con-
tacts was also reported for dibismuthines, R2Bi-BiR2.14
1H NMR spectra of a solution of crystals of 6 in C6D6
show more signals than expected, although mass spectra
of this solution did not contain additional signals. In
the NMR spectra, instead of one there are two sets of
signals for Me3SiCH2 groups. These signals are also
observed during the formation of 6 by decomposition of
5. The ratio of intensities does not significantly change
between -70 and +80 °C, but the pattern of one of the

Neopentyl and (Me3Si)CH2 Sb and Bi Oligomers
Organometallics, Vol. 22, No. 14, 2003 2923
Ta ble 1. Cr ysta l Da ta , Da ta Collection , a n d Str u ctu r e Refin em en t P a r a m eter s for 1b, 4, a n d 6
1b
4
7
formula
fw
color
temp (K)
cryst size (mm)
wavelength (Å)
cryst syst
space group
a (Å)
C
25H55Sb5
C
20H22Bi2O10W2
C
13H22Bi2O5Si2W
964.44
yellow
173
0.5 × 0.25 × 0.1
0.710 73 (Mo KR)
orthorhombic
P21nb
10.4954(13)
11.8461(16)
29.222(9)
90
1208.04
orange
173
0.4 × 0.2 × 0.15
0.710 73 (Mo KR)
monoclinic
P21/m
916.30
orange
173
0.4 × 0.1 × 0.1
0.710 73 (Mo KR)
monoclinic
P21/n
6.5970(10)
22.702(5)
15.422(3)
90
93.98(3)
90
4
2304.1(8)
2.782
20.337
9.456(2)
b (Å)
c (Å)
12.090(2)
12.779(3)
90
99.17(3)
90
R (deg)
â (deg)
γ (deg)
Z
90
90
4
2
V (Å3)
3633.2(12)
1.763
3.680
1442.3(5)
2.782
20.158
dcalcd (g cm-3
)
µ (mm-1
F(000)
)
1840
1072
1632
θ range (deg)
2.68-25.01
-1 e h e 12, -14 e k e 1,
-34 e l e 1
4344
3659 (R(int) ) 0.0606)
3659/245/289
empirical (DIFABS)
0.0674
2.33-26.10
-11 e h e 11, -14 e k e 14,
-15 e l e 15
20 533
2960 (R(int) ) 0.0664)
2960/0/181
empirical (DIFABS)
0.0237
2.23-26.10
-8 e h e 8, -28 e k e 27,
-18 e l e 18
22 162
4399 (R(int) ) 0.0523)
4399/0/216
empirical (DIFABS)
0.0229
index ranges
no. of measd data
no. of unique data [R(int)]
no. of data/restraints/params
abs cor
R1 (I > 2σ(I))
wR2 (I > 2σ(I))
0.1177
0.1359
0.0581
0.0329
0.0431
0.0374
R1 (all data)
wR2 (all data)
0.1493
1.019
1.633, -1.132
0.0607
1.057
1.325, -1.101
0.0464
0.914
0.816, -0.769
goodness of fit on F2
max, min residual density (e Å-3
)
assignable to the cis and trans isomers of [(Me3CCH2-
Bi)2W(CO)5] were observed.
Con clu sion s
With (RE)n (E ) Sb, Bi; R ) Me3CCH2, Me3SiCH2,
(Me3Si)2CH) there are now three pairs of ring systems
available for comparative studies, and characteristic
differences between analogous Sb and Bi monocycles are
emerging. All three bismuth ring systems take part in
ring-ring equilibria with pronounced preferences for
the trimers in solution. In contrast, there are no
antimony trimers (tristibiranes) involved in equilibria.
A common feature of the antimony and bismuth ring
systems is the existence of pentamers (R ) Me3CCH2,
Me3SiCH2) or tetramers (R ) (Me3Si)2CH) in the
crystalline state. Reactions with W(CO)5(thf) again
reveal fundamental differences. The cyclostibines (RSb)n
(R ) Me3SiCH2, (Me3Si)2CH) coordinate as intact cyclic
ligands, whereas the bismuth rings (RBi)n (R ) Me3-
SiCH2, Me3CCH2) are readily transformed into dibis-
muthene ligands.
F igu r e 8. 1H NMR spectra (200 MHz) of (o) [(Me3SiCH2-
Bi)2{W(CO)5}2] (5) and [(Me3SiCH2Bi)2W(CO)5] (6; (x) cis
form, (*) trans form).
CH2 signals is temperature dependent (Figure 8). A
straightforward interpretation of these data is to as-
sume the presence not only of the trans but also of the
cis isomers of 6 in solution. The more intense signals
are assigned to the trans form, which should be more
stable and is prevailing in the crystalline state. Cis-
trans isomerization has also been observed in the
chemistry of diphosphene complexes. However, photo-
chemical methods are required.15 Removal of the tung-
sten carbonyl unit from 5 with formation of Ph3PW(CO)5
and (Me3SiCH2Bi)n (n ) 3, 5)6 is achieved by addition
of excess Ph3P. In a 1H NMR study in C6D6 also the
thermal decomposition of 4 was studied, and signals
Exp er im en ta l Section
Gen er a l Com m en ts. All the syntheses were carried out
under an argon atmosphere using dried solvents distilled
under argon prior to use. The NMR spectra were recorded on
a Bruker DPX 200 instrument. For the mass spectrometry a
Finnigan MAT 8222 instrument was used, and for IR spectra
a FT-IR SPEKTRUM 1000 instrument was employed.
X-r a y Cr ysta llogr a p h y. Table 1 contains a summary of
the structural analyses reported in this paper. Data for 1b
were collected on a Siemens P4 four-circle diffractometer. For
4 and 7 the data were collected using a STOE IPDS diffrac-
tometer. In both cases a graphite monochromator with the
(15) Yoshifuji, M.; Hashida, T.; Inamoto, N.; Hirotsu, K.; Horiuchi,
T.; Higuchi, T.; Ito, K.; Nagase, S. Angew. Chem. 1985, 97, 230; Angew.
Chem., Int. Ed. Engl. 1985, 24, 211.

2924 Organometallics, Vol. 22, No. 14, 2003
Bala´zs et al.
wavelength (Mo KR) 0.710 73 Å was used. The crystals were
attached with Kel-F oil to a glass fiber and cooled under a
nitrogen stream at 173 K. The structures were solved by direct
methods (full-matrix least squares on F2). All non-hydrogen
atoms were refined with anisotropic thermal parameters. For
structure solution and refinement the software package SHELX-
97 was used.16 The drawings were created by the Diamond
program from Crystal Impact GbR.17
9H; CH3), 0.96 (s, 18H; CH3), 2.81 (s, 2H; CH2), AB spin system
with A at 2.59 and B at 2.88 (2J HH ) 10.58 Hz, 4H; CH2); for
2b, δ 1.06 (s, 18H; CH3), 1.07 (s, 18H; CH3), 1.08 (s, 9H; CH3),
3.79 (s, 2H; CH2), 3.89 (s, 4H; CH2), AB spin system with A at
3.73 and B at 4.35 (2J HH ) 10.8 Hz, 4H; CH2).
(Me3CCH2)4Bi2 (3). A solution of 1.50 g (1.78 mmol) of 2a ,b
in 50 mL of Et2O was stirred for 24 h at room temperature,
filtered through a frit covered with Kieselguhr, concentrated,
and cooled to -28 °C, at which point 0.61 g (64%) of orange-
(Me3CCH2Sb)n (n ) 4 (1a ), 5 (1b)). A solution of 18.25 g
(51.8 mmol) Me3CCH2SbBr2 in 80 mL of thf was added
dropwise to 1.37 g (56.9 mmol) of Mg covered with 20 mL of
thf. The reaction mixture was stirred for 12 h at room
temperature, at which point the color changed from yellow to
brown. The thf was evaporated at low pressure, and the
resulting residue was extracted with petroleum ether (4 × 80
mL). Concentration of the solutions and cooling to -28 °C gave
6.1 g (60.9%) of cyclo-(Me3CCH2Sb)n as a yellow-brown crystal-
line solid, mp 128-129 °C. Single crystals of 1b were grown
from a petroleum ether solution at -28 °C over 4 weeks. Anal.
Calcd for C25H55Sb5 (964.50): C, 31.13; H, 5.75. Found: C,
30.89; H, 5.66. 1H NMR (200 MHz, C6D6, 25 °C, TMS): for 1b,
red crystals of 3 formed, mp 72-74 °C. Anal. Calcd for C20H44
-
Bi2 (702.53): C, 34.19; H, 6.31. Found: C, 33.77; H, 6.38. 1H
NMR (200 MHz, C6D6, 25 °C, TMS): δ 1.11 (s, 9H; CH3), AB
spin system with A at 2.40 and B at 3.26 (2J HH ) 10.8 Hz, 2H;
CH2). 13C NMR (50 MHz, C6D6, 25 °C, TMS): δ 31.83 (s, CMe3),
33.33 (s, CH2), 33.39 (s, CH3). MS (EI, 70 eV; m/z (relative
intensity, %)): 702 (25) [M+], 631 (18) [M+ - R], 560 (6) [M+
- 2R], 351 (42) [R2Bi+], 71 (100) [R+] (R ) Me3CCH2).
(Me3CCH2Bi)2[W(CO)5]2 (4). A solution of 0.13 g (0.31
mmol) of W(CO)5(thf) in 100 mL of thf was added to 0.26 g
(0.31 mmol) of 2 in 10 mL of thf at 0 °C. After the mixture
was stirred for 3 h at 0 °C, the solvent was removed and the
residue was extracted with 50 mL of petroleum ether. The
extracts were filtered through a frit covered with Kieselguhr.
Concentrating and cooling the solution to -28 °C gave 0.25 g
(65.7%) of light red crystals of 4, mp 86-88 °C dec. HRMS
(m/z): [M- - R] calcd, 1 132.892 46; found, 1132.8925; R )
1
1
δ 1.07 (s, J CH ) 124.5 Hz, 18H; CH3), 1.08 (s, J CH ) 124.3
1
Hz, 9H; CH3), 1.10 (s, J CH ) 123.6 Hz, 18H; CH3), AB spin
system with A at 2.60 and B at 2.78 (2J HH ) 12.38 Hz, 4H;
CH2), 2.68 (s, 2H; CH2), AB spin system with A at 2.67 and B
at 2.73 (2J HH ) 10.72 Hz, 4H; CH2); for 1a , δ 1.05 (s, 9H; CH3),
2.64 (s, 2H; CH2). 13C NMR (50 MHz, C6D6, 25 °C, TMS): for
1b, δ 29.61 (s, CH2), 29.65 (s, CH2), 31.17 (s, CH2), 31.66 (s,
CH3), 31.87 (s, CH3), 32.04 (s, CH3), 32.35 (s, CMe3), 32.46 (s,
CMe3), 32.52 (s, CMe3); for 1a , δ 29.37 (s, CH2), 31.51 (s, CMe3),
32.36 (s, CH3). MS (EI, 70 eV; m/z (relative intensity, %)): 964
(6) [R5Sb5+], 893 (18) [R4Sb5+], 768 (6) [R4Sb4+], 701 (9) [R3-
Sb4+], 71 (100) [R+] (R ) Me3CCH2).
1
6000. H NMR (200 MHz, C6D6, 25 °C, TMS): δ 1.04 (s, 9H;
CH3), 2.69 (s, 2H; CH2). 13C NMR (50 MHz, C6D6, 25 °C,
TMS): δ 32.93 (s, CH2), 33.24 (s, CH3), 33.36 (s, CMe3), 190.0
(s, CO), 192.1 (s, CO). IR (Nujol): 2053, 1948 cm-1 (ν(CO)).
MS (EI, 70 eV; m/z (relative intensity, %)): 1135 (2) [M+
-
R], 884 (25) [M+ - W(CO)5], 813 (35) [RBi2W(CO)5+], 742 (25)
[Bi2W(CO)5+], 729 (12) [RBi2W(CO)2+], 714 (20) [Bi2W(CO)4+],
701 (15) [RBi2W(CO)+], 686 (15) [Bi2W(CO)3+], 673 (12)
[RBi2W+], 658 (14) [Bi2W(CO)2+], 636 (15) [Bi2W(CO) +], 602
(10) [Bi2W+], 209 (10) [Bi+], 71 (100) [R+] (R ) Me3CCH2).
(Me3SiCH2Bi)2W(CO)5 (6). A solution of 0.97 g (0.78 mmol)
of (Me3SiCH2Bi)2[W(CO)5]2 (5)6 in 50 mL of petroleum ether
was stirred at room temperature for 36 h and filtered through
a frit covered with Kieselguhr. After the solution was concen-
trated, it was cooled to -28 °C and crystals of 5 precipitated
as the first fraction. The second fraction contained 5 and 0.1
g (14%) of red crystals of trans-6, mp 71-73 °C. HRMS (m/z):
[M+] calcd, 914.009 58; found, 914.007 18; R ) 10 000. 1H
NMR (200 MHz, C6D6, 25 °C): for trans-6, δ 0.08 (s, 9H; CH3),
AB spin system with A at 2.24 and B at 3.11 (2J HH ) 12.22
Hz, 2H; CH2); for cis-6, δ 0.14 (s, 9H; CH3), 2.44 (s, 2H; CH2).
IR (Nujol): 2059, 1956 cm-1 (ν(CO)). MS (EI, 70 eV; m/z
(relative intensity, %)): 916 (55) [M+], 829 (100) [M+ - R],
773 (42) [RBiW(CO)4+], 745 (78) [RBiW(CO)3+], 742 (25) [Bi2W-
(CO)5+], 717 (40) [RBiW(CO)2+], 714 (20) [Bi2W(CO)4+], 687 (40)
[RBiW(CO)+], 658 (20) [Bi2W(CO)2+], 505 (18) [RBi2+], 418 (10)
[Bi2+] 209 (10) [Bi+], 87 (29) [R+], (R ) Me3SiCH2).
(Me3CCH2Bi)n (n ) 3 (2a ), 5 (2b)). A Grignard solution
prepared from 4.08 g (38.3 mmol) of Me3CCH2Cl and 2.4 g (65.0
mmol) of Mg in 110 mL of thf was added dropwise to a
suspension of 13.74 g (34.4 mmol) of Ph2BiCl in 100 mL of
thf. The reaction mixture was stirred for 2 h at 0 °C and 18 h
at room temperature. The thf was removed under vacuum, and
the residue was extracted with petroleum ether. After removal
of the solvent 8.46 g (56.6%) Me3CCH2BiPh2 remained as a
yellowish oil. Injection of HCl gas for 2 h at 0 °C into a solution
of 8.46 g (19.5 mmol) of Me3CCH2BiPh2 in 100 mL of CHCl3,
stirring for 30 min, and removal of the solvent gave 5.45 g of
a yellowish solid consisting of Me3CCH2BiCl2. 1H NMR (200
MHz, (CD3)2SO, 25 °C, TMS): δ 1.91 (s, 9H; CH3), 2.30 (s, 2H;
CH2), 13C NMR (50 MHz, (CD3)2SO, 25 °C, TMS): δ 34.24 (s,
CH2), 36.46 (s, CH3), 37.04 (s, CMe3), MS (70 eV): m/z (%):
351 (52) [M+], 280 (25) [M+ - 2Cl], 209 (10) [Bi+], 71 (100)
[R+] and BiCl3, MS (70 eV): m/z: 314 [M+], as impurity
(<10%). This solid was solved in 150 mL of Et2O and cooled
to -70 °C. Portionwise addition of 1.81 g (47.6 mmol) of LiAlH4
to the precooled (-70 °C) solution, stirring for 4 h, and
filtration at -30 °C through a precooled frit covered with
Kieselguhr gave a dark red-brown solution of 2. After the
removal of the solvent under vacuum 3.58 g (82.3%) of 2
remained as a red-brown solid, mp 60-62 °C. Anal. Calcd for
Ack n ow led gm en t. The support of this work by the
Deutsche Forschungsgemeinschaft and Universita¨t Bre-
men is gratefully acknowledged.
C
25H55Bi5 (1400.61): C, 21.44; H, 3.96. Found: C, 21.28; H,
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and refinement details, atomic coordinates and U values,
bond distances and angles, anisotropic thermal parameters,
and dihedral angles. This material is available free of charge
via the Internet at http://pubs.acs.org.
1
4.05. H NMR (200 MHz, C6D6, 5 °C, TMS): for 2a , δ 0.95 (s,
(16) Sheldrick, G. M. SHELX-97; Universita¨t Go¨ttingen, Go¨ttingen,
Germany, 1997.
(17) Brandenburg, K. DIAMOND, Version 2.1c; Crystal Impact GbR,
1999.
OM0301435