Syntheses of a stable tristibine and of related antimony compounds with the 2,6-dimesitylphenyl (Dmp) substituent

Article abstract of DOI:10.1016/j.jorganchem.2008.04.038

DmpSbBr₂ (Dmp = 2,6-Mes₂C₆H₃) (1) is obtained by the reaction of DmpMgBr with SbCl₃. The reaction of 1 with KI in ethanol gives DmpSbI₂ (2). Dmp(Ph)SbBr (3) is prepared from DmpMgBr and PhSbCl₂. Compound 1 or 3 react with LiAlH₄ to form DmpSbH₂ (4) or Dmp(Ph)SbH (5). Compound 4 reacts with MeI in presence of DBU to give Dmp(Me)SbH (6). DmpSb(SbMe₂)₂ (7) is obtained from 4 and Me₄Sb₂. Elimination of hydrogen from 6 gives [Dmp(Me)Sb]₂ (8). Hydrolysis of 3 gives Dmp(Ph)SbOH (9). The molecular structures of 1-3, 5, 8 and 9 were determined by X-ray diffraction on single crystals.

Full text of DOI:10.1016/j.jorganchem.2008.04.038

Journal of Organometallic Chemistry 693 (2008) 2527–2534
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Journal of Organometallic Chemistry
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Syntheses of a stable tristibine and of related antimony compounds with the
2,6-dimesitylphenyl (Dmp) substituent
*
H.J. Breunig , E. Lork, O. Moldovan, C.I. Raßt
Institut für Anorganische und Physikalische Chemie, Fachbereich 2 der Universität Bremen, Postfach 330 440, D-28334 Bremen, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
DmpSbBr2 (Dmp = 2,6-Mes2C6H3) (1) is obtained by the reaction of DmpMgBr with SbCl3. The reaction of
1 with KI in ethanol gives DmpSbI2 (2). Dmp(Ph)SbBr (3) is prepared from DmpMgBr and PhSbCl2. Com-
pound 1 or 3 react with LiAlH4 to form DmpSbH2 (4) or Dmp(Ph)SbH (5). Compound 4 reacts with MeI in
presence of DBU to give Dmp(Me)SbH (6). DmpSb(SbMe2)2 (7) is obtained from 4 and Me4Sb2. Elimina-
tion of hydrogen from 6 gives [Dmp(Me)Sb]2 (8). Hydrolysis of 3 gives Dmp(Ph)SbOH (9). The molecular
structures of 1–3, 5, 8 and 9 were determined by X-ray diffraction on single crystals.
Ó 2008 Elsevier B.V. All rights reserved.
Received 27 March 2008
Received in revised form 25 April 2008
Accepted 28 April 2008
Available online 6 May 2008
Keywords:
Antimony
Terphenyl
X-ray structure
Hydride
Hydroxide
1. Introduction
oxides. A complex with a diorganoantimony hydroxide ligand was
reported recently [8].
The 2,6-dimesitylphenyl (Dmp) and related terphenyl groups
(2,6-Trip2C6H3, Trip = 2,4,6-iPr3C6H2) were used in antimony chem-
istry to stabilize the Sb@Sb bond or to protect labile bonds like Sb–
H. The stable distibenes: (RSb)2 R = Dmp or 2,6-Trip2C6H3 [1], the
hydrides DmpSbH2 (4) [2], RSbH2 and RSb(Li)H, R = 2,6-Trip2C6H3
[3], and their precursors DmpSbCl2 [1,4] and 2,6-Trip2C6H3SbCl2
[1] were obtained. The Dmp group was also used to protect the
P3 unit in DmpP(PPh2)2 [5].
Our aim was to stabilize catena-tristibines of the types I and II
(Scheme 1) with the Dmp group. Known catena-stibines exist as
mixtures of Sb3 and Sb4 chains, as components of ring-chain equi-
libria, or as ligands in transition metal carbonyl complexes [6].
We report here the stepwise syntheses of the type I tristibine,
DmpSb(SbMe2)2 (7) and the formation and characterization of pre-
cursors of type II tristibines with terminal Dmp(Me)Sb and
Dmp(Ph)Sb groups. In this context, we have prepared the com-
pounds DmpSbX2, X = Br (1), I (2), H (4); Dmp(Ph)SbX, X = Br (3),
H (5), OH (9); Dmp(Me)SbX, X = H (6), Sb(Me)Dmp (8). Compound
4 was prepared before by another route [2]. The compounds 3, 5, 6
and 9 are of interest as racemic Sb-chiral stibines. A related stibine
with a known crystal structure is RR0SbCl [R = 2-(Me2NCH2)C6H4,
R0 = CH(SiMe3)2] [7]. Compound 9 is the first authentic diorganoan-
timony hydroxide (stibinic acid). Compounds that were called
diorganoantimony hydroxides in the older literature were actually
2. Results and discussion
DmpSbBr2 (1) is obtained by the reaction of DmpMgBr with
SbCl3. Due to the presence of bromide in the reaction mixture ha-
lide exchange occurs. Reaction of 1 with excess KI in ethanol leads
quantitatively to DmpSbI2 (2). Compound 1 reacts with LiAlH4 to
give DmpSbH2 (4) in a similar way like DmpSbCl2 [2]. Reacting 4
with MeI in the presence of DBU in a 1:1:1 molar ratio leads to
the selective substitution of one hydrogen atom with formation
of light sensitive Dmp(Me)SbH (6). Photolysis of a solution of 6
in C6D6 in a NMR tube in day light gives the racemic Sb chiral dis-
tibine [Dmp(Me)Sb]2 (8). Crystals of 8 were obtained by catalytic
hydrogen removal in presence of Cp2Ti(Me3SiC)2 [9]. The role of
group 4 metallocenes as catalysts for the elimination of hydrogen
from organoantimony(III) hydrides was reported before [2]. Addi-
tion of excess tetramethyldistibine to 4 leads to DmpSb(SbMe2)2
(7). Compound 7 is the first catena-tristibine isolated in pure state.
Attempts to obtain single crystals of 7 suitable for X-ray diffraction
failed. The reaction of DmpMgBr and PhSbCl2 gives Dmp(Ph)-
SbBr (3). Reaction of 3 with LiAlH4 leads to the chiral secondary sti-
bine Dmp(Ph)SbH (5). Attempts to obtain the tristibine
DmpSb[Sb(Ph)Dmp]2 by UV photolysis of solutions containing stoi-
chiometric mixtures of 4 and 5 were not successful due to the sta-
bility of 5 under these conditions. In a serendipitous reaction,
when the purification of 3 by column chromatography was in-
tended, the hydroxide Dmp(Ph)SbOH (9) was obtained as solid.
* Corresponding author. Tel.: +49 421 218 2266; fax: +49 421 218 4042.
E-mail address: hbreunig@uni-bremen.de (H.J. Breunig).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.04.038

2528
H.J. Breunig et al. / Journal of Organometallic Chemistry 693 (2008) 2527–2534
rotation is observed for the DmpSbX2 type compounds 1, 2, 4
and 7 where the ortho methyl groups are equivalent. In 6 the SbCH3
protons are coupled with the SbH proton and a doublet and a qua-
druplet signal appear in the spectrum. The coupling is observed
also in the COSY spectrum of the compound. The 1H NMR spectrum
of the tristibine 7 is depicted in Fig. 2. It shows the pattern for the
Dmp group and two characteristic signals for the diastereotopic
methyl groups directly attached to peripheric antimony atoms. In
the HMBC spectrum of 7 a three bond correlation between the
hydrogen atoms of the methyl group and the carbon atoms of
the other methyl group attached to the same antimony atom is ob-
served. The 13C NMR spectrum of 7 shows as well two signals for
the methyl groups bonded to antimony. The 1H NMR spectra of 8
show the presence of only one diastereomeric form, assigned on
the basis of the X-ray diffraction results, as R,R and S,S form.
The IR spectra of 5 and 6 in Nujol display characteristic signals
at 1883 and 1870 cmꢁ1 for the SbH stretching vibration.
The molecular structures of 1–3, 5, 8 and 9 were determined by
single crystal X-ray diffraction. The antimony atoms in all the
structures have pyramidal geometries with unexceptional bond
lengths and angles. In the typical way for terphenyl substituents
the flanking mesityl groups are orientated perpendicular to the
plane of the central phenyl ring and close contacts between the
antimony centres and the carbon atoms of the mesityl ring result.
These contacts are partially imposed by the geometry of the ter-
phenyl substituent but they depend also in a significant way on
the nature of the inorganic substituents at the antimony centres.
Particularly close intramolecular contacts comparable with the
Scheme 1.
The synthetic pathways leading to 1–9 are summarized in
Scheme 2.
The compounds 1–9 are yellow (1–3, 7 and 8) or colourless (4–6
and 9) solids, soluble in aromatic solvents and little soluble in ali-
phatic solvents with exception of the hydrides 4–6. Solutions of 1–
6, 8 and 9 are air sensitive. The thermal stability of the hydride 5,
which does not decompose at 3 ꢀ 10ꢁ2 mbar at 200 °C is remark-
able. The analogous stibine Ph2SbH decomposes above 20 °C [10].
Compounds 1–9 were characterized by mass spectrometry, 1H,
13C, HSQC, HMBC, COSY (6) NMR spectroscopy, infrared spectros-
copy (5, 6 and 9) and elemental analyses (1–3 and 9). Mass spectra
of 1–3, 6, 7 and 9 contain molecular ions. The composition of 3 was
also confirmed by HRMS. The molecular ion of the tristibine 7
found in the EI-MS and the theoretical isotopic distributions are
shown in Fig. 1.
The 1H NMR spectra of 1–7 show characteristic signals for the
Dmp group and for the hydrogen atoms bonded to antimony where
the case. The signal assignment was performed using HSQC and
HMBC spectra. The 1H NMR spectra of the compounds of the type
DmpSbX2 X = Br (1), I (2), H (4), SbMe2 (7) contain two signals, the
spectra of 3, 6, 8 and 9 three signals for the mesityl methyl groups.
In the 1H NMR spectrum of 5 there are only two signals for the
methyl groups visible due to overlapping of signals. These findings
indicate that the rotation of the m-terphenyl substituents around
the Sb–Cipso bond is hindered in the Dmp(R)SbX type compounds
3, 5, 6, 8 and 9 where three methyl signals occur, whereas free
well known
p interactions in Menshutkin complexes between are-
nes and antimony trihalides [11] exist in the organoantimony diha-
lides 1 and 2, which crystallize with 4 (1) or 2 (2) different
monomeric molecules in the asymmetric unit. The only other
known example of an organoantimony dihalide that crystallizes
as monomer is 2,6-Trip2C6H3SbCl2 [1]. DmpSbCl2, the dichloride
analogue of 1 forms dimers with chlorine bridges in the solid state
[4]. Solid phenyl- or methylantimony dihalides are polymeric
[12,13]. Representative molecular structures of 1 and 2 are shown
in Figs. 3 and 4.
Under the influence of the intra molecular contacts the anti-
mony halogen bonds in 1 and 2 are not much shorter than in the
corresponding methyl- or phenylantimony dihalides where inter-
molecular interactions are important (Sb–Br, 1: 2.5124(15),
2.5164(15); MeSbBr2: 2.564(3), 2.583(3) [13], PhSbBr2: 2.526(1),
2.563(1) Å [12]. Sb–I, 2: 2.7049(14), 2.7019(11); MeSbI2:
2.799(2), 2.761(2) [14], PhSbI2: 2.753(1), 2.738(1) Å [12]). The
intramolecular interactions between the SbX2 unit and the oppo-
site mesityl groups in 1 and 2 lead to a bending of the Dmp groups
which can be quantified by the difference between the bonding an-
gles at the Cipso atom of the central phenyl group. The found values
are 22.6°, 22.2°, 21.5° and 20.5° for 1 and 21.7° and 22.2° for 2.
These values are close to the reported values for DmpSbCl2 (20.9°
and 20.3°) [4] and 2,6-Trip2C6H3SbCl2 (22.5°) [1].
Compound 3 crystallizes as a mixture of R and S isomers in a ra-
tio of 1:1 in the C2/c space group with eight molecules per unit cell.
The molecular structure of (S)-3 is shown in Fig. 5.
The antimony bromine bond length (2.5264(15) Å) in 3 is sim-
ilar to the one found in Ph2SbBr (2.553(1) Å [15]). The direction
of Sb–Br bond is almost perpendicular to the plane of the central
phenyl group of Dmp substituent.
Crystals of 5 contain pairs of enantiomers which are symmetry
related, with respect to the inversion centres of the space group.
Between the molecules there is a contact with a Sbꢂ ꢂ ꢂSb distance
P
of 3.941(2) Å, which is close to rvdw(Sb,Sb) = 4.0 Å [16]. The struc-
ture of two associated molecules of 5 is shown in Fig. 6.
The value for Sb–H bond length of 1.59(7) Å in the structure of 5
is similar to the Sb–H distance determined by X-ray diffraction of
Scheme 2.

H.J. Breunig et al. / Journal of Organometallic Chemistry 693 (2008) 2527–2534
2529
Fig. 1. Measured (down left) and calculated (up right) isotopic pattern of [C28H37Sb3]+ ([DmpSb(SbMe2)2]+) (7).
Fig. 2. 1H NMR spectrum of DmpSb(SbMe2)2 (7).
{(Me3Si)2CH2SbH}2 (1.58(3) Å) [17]. The distibine 8 crystallized as
1:1 solvate with C6D6. The crystals contain the R,R and S,S isomers
in a 1:1 ratio. The structure of the R,R isomer of 8 is shown in Fig. 7.
The Sb–Sb bond length in 8 is 2.8371(7) Å, almost the same as in
{(Me3Si)2CH(H)Sb}2 (2.8304(8) Å) [17]. Compound 8 adopts a close
to antiperiplanar conformation with the torsion angle between
Dmp groups of 155.30(15)°.
Between the dimers there are loose Sbꢂ ꢂ ꢂO contacts (3.520(7),
P
3.377(11) Å) close to
rvdW(Sb,O) = 3.52 Å [16]. The Sb–O bond
lengths are in the range of the analogous values encountered oxi-
des of the type (R2Sb)2O [18].
3. Conclusion
The present results illustrate the role of terphenyl substituents
in stabilising unusual organoantimony compounds. With sterical
Crystals of 9 contain the R and S isomers in the 1:1 molar ratio.
Two molecules are associated to dimers as shown in Fig. 8.

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H.J. Breunig et al. / Journal of Organometallic Chemistry 693 (2008) 2527–2534
Fig. 5. Thermal ellipsoid representation (40%) of (S)-Dmp(Ph)SbBr (3). Hydrogen
atoms are omitted for clarity. Selected interatomic distances (Å) and angles (°):
Fig. 3. Thermal ellipsoid representation (50%) of one molecule of DmpSbBr2 (1).
Hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (°):
Br(1)–Sb(1)
2.5264(15),
C(1)–Sb(1)
2.190(9),
C(25)–Sb(1)
2.149(9),
Sb(1)–C(1)
2.174(9),
Sb(1)–Br(1)
2.5124(15),
Sb(1)–Br(2)
2.5164(15),
C(1)–Sb(1)–Br(1) 97.8(2), C(25)–Sb(1)–C(1) 105.0(3), C(25)–Sb(1)–Br(1) 96.1(3),
C(2)–C(1)–Sb(1)–Br(1) 92.3(8).
C(1)–Sb(1)–Br(1) 101.7(2), C(1)–Sb(1)–Br(2) 99.8(2), Br(1)–Sb(1)–Br(2) 97.05(5).
C and H elemental analyses were performed by Mikroanalytisches
Laboratorium Beller-Matthies in Göttingen, Germany.
4.1. Synthesis of DmpSbBr2 (1)
A solution of DmpMgBr was added dropwise to a solution of
4.56 g (20 mmol) SbCl3 in 20 ml THF. The reaction mixture was
stirred for 16 h at room temperature. The solvent mixture was re-
moved under reduced pressure and the product extracted with
200 ml toluene. Single crystals suitable for X-ray diffraction were
obtained from petroleum ether solutions at 7 °C. Yield: 3.57 g
(30%), m.p. 75–76 °C. 1H NMR (200.1 MHz): d 2.11 (s, 12H,
o-CH3), 2.14 (s, 6H, p-CH3), 6.79 (m, 4H, m-Mes), 6.84 (d, 2H, m-
C6H3, JHH = 7.1 Hz), 7.11 (dd, 1H, m-C6H3, JHH = 7.1 Hz). 13C NMR
(50.3 MHz, C6D6): d 21.3 (p-CH3), 21.7 (o-CH3), 128.9 (m-Mes),
130.2 (m-C6H3), 132.0 (p-C6H3), 136.5 (i-Mes), 137.1 (o-Mes),
138.6 (p-Mes), 144.6 (i-C6H3), 148.6 (o-C6H3). MS (EI, 70 eV) m/z
(relative intensity %): 592 (6.4) [M]+, 513 (55.4) [MꢁBr]+, 312
[DmpꢁH]+. Anal. Calc. for C24H25SbBr2 (595.01): C, 48.45; H, 4.23.
Found: C, 48.55; H, 4.50%.
3
3
Fig. 4. Thermal ellipsoid representation (30%) of one molecule of DmpSbI2 (2).
Hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (°):
Sb(1)–C(1) 2.176(7), Sb(1)–I(1) 2.7049(14), Sb(1)–I(2) 2.7019(11), C(1)–Sb(1)–I(1)
105.5(2), C(1)–Sb(1)–I(2) 102.36(19), I(1)–Sb(1)–I(2) 97.21(4).
4.2. Synthesis of DmpSbI2 (2)
A mixture of 1.64 g (2.75 mmol) 1 and 1.11 g (3.34 mmol) KI
were stirred in 60 ml EtOH for 3 days at room temperature. The
solvent was removed under reduced pressure and the solid ex-
tracted with 60 ml benzene. Yield: 1.8 g (94%), m.p. 115–116 °C.
1H NMR (200.1 MHz): d 2.13 (s, 12H, o-CH3), 2.16 (s, 6H, p-CH3),
6.80 (s, 2H, m-Mes), 6.84 (d, 2H, m-C6H3), 7.14 (dd, 1H, p-C6H3).
13C NMR (50.3 MHz, C6D6): d 21.4 (p-CH3), 22.1 (o-CH3), 129.2
(m-Mes), 129.7 (m-C6H3), 131.8 (p-C6H3), 133.7 (i-C6H3), 137.1 (o-
Mes), 137.2 (i-Mes), 138.6 (p-Mes), 148.8 (o-C6H3). MS (EI,
70 eV): 561 (100) [MꢁI]+; (CI, positive): 706 (100) [M+NH4]+, 561
(47.2) [MꢁI]+.
protection by the Dmp group a catena-tristibine, racemic Sb-chiral
secondary stibines and distibines as well as a diorganoantimony
hydroxide were obtained. All these new products are promising
starting materials for further work in the syntheses and charac-
terisation of catena-stibines, Sb-chiral stibines and other useful
organoantimony compounds.
4. Experimental
The reactions and manipulations of the air sensitive compounds
were performed in an atmosphere of argon using modified Schlenk
techniques. All solvents were dried and freshly distilled. SbCl3 and
BiCl3 were sublimed prior to use. The syntheses of DmpMgBr and
DmpSbH2 were reported before [2,19]. NMR spectra were recorded
in C6D6 on Bruker DPX-200 and NB-360 spectrometers. Mass spec-
tra were recorded on Finnigan MAT 95 (EI, FD, HRMS), Finnigan
MAT 8200 (EI, CI). The pattern of antimony containing ions was
compared with theoretical values calculated using MASPECII. The
4.3. Synthesis of Dmp(Ph)SbBr (3)
A solution of DmpMgBr was added dropwise to a solution 5.4 g
(20 mmol) PhSbCl2 in 30 ml THF. After 16 h of stirring the solvent
was removed at reduced pressure. The product was extracted with
50 ml toluene. Crystals suitable for X-ray diffraction were obtained
by cooling a benzene solution to ꢁ10 °C. Yield: 4.1 g (35%), m.p.

H.J. Breunig et al. / Journal of Organometallic Chemistry 693 (2008) 2527–2534
2531
Fig. 6. Thermal ellipsoid representation (30%) of dimeric units in the structure Dmp(Ph)SbH (5). The carbon bonded hydrogen atoms were omitted for clarity. Selected bond
lengths (Å) and angles (°): Sb(1)–H(1) 1.59(7), Sb(1)–C(1) 2.165(7), Sb(1)–C(25) 2.148(9), Sb(1)ꢂ ꢂ ꢂSb(10) 3.941(2), C(1)–Sb(1)–C(25) 102.1(3), C(1)–Sb(1)–H(1) 95(2), C(25)–
Sb(1)–H(1) 93(2); C(2)–C(1)–Sb(1)–C(25) 127.4(6)°.
Fig. 7. Thermal ellipsoid representation (30%) of (R,R)-{2,6-Mes2C6H3(Me)Sb}2 (8). Hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (°): Sb(1)–
Sb(2) 2.8371(7), C(1)–Sb(1) 2.200(4), C(25)–Sb(2) 2.198(4), C(49)–Sb(1) 2.179(5), C(50)–Sb(2) 2.170(5), C(1)–Sb(1)–C(49) 103.21(17), C(1)–Sb(1)–Sb(2) 98.09(10), C(49)–
Sb(1)–Sb(2) 91.50(14), C(25)–Sb(2)–C(50) 102.89(17), C(25)–Sb(2)–Sb(1) 98.47(10), C(50)–Sb(2)–Sb(1) 92.25(13), C(1)–Sb(1)–Sb(2)–C(25) 155.30(15), C(49)–Sb(1)–Sb(2)–
C(50) 51.65(19), C(1)–Sb(1)–Sb(2)–C(50) 51.91(17), C(49)–Sb(1)–Sb(2)–C(25) 51.74(17).
137–138 °C. 1H NMR (360.1 MHz, C6D6): d 2.01, 2.06 (s, 12H,
o-CH3), 2.15 (s, 6H, p-CH3), 6.60, 6.76 (m, 2H, m-Mes), 6.86
(d, 2H, m-C6H3), 6.87 (m, 1H, p-Ph), 6.91 (m, 2H, m-Ph), 7.13 (dd,
1H, p-C6H3), 7.19 (m, 2H, o-Ph). 13C NMR (90 MHz, C6D6): d 21.2
(p-CH3), 21.5, 21.7 (o-CH3), 128.3 (m-Ph), 128.4 (p-Ph), 128.8
(m-Mes), 129.7 (m-C6H3), 130.9 (p-C6H3), 134.6 (o-Ph), 136.4,
136.5 (o-Mes), 137.6 (p-Mes), 138.8 (i-Mes), 141.0 (i-Ph), 141.8
(i-C6H3), 149.3 (o-C6H3). MS (EI, 70 eV) m/z (relative intensity %):
590 (22.7) [M]+, 511 (45.0) [MꢁBr]+, 312 (38.9) [DmpꢁH]+. HRMS
(EI, 70 eV) m/z: Calc. for [M]+ C30H3079Br121Sb, 590.05691; found,
590.05691. Anal. Calc. for C30H30BrSb (592.22): C, 60.84; H, 5.11.
Found: C, 60.69; H, 5.30%.
4.4. Synthesis of DmpSbH2 (4)
A suspension of 3.3 g (5.5 mmol) DmpSbBr2 in 100 ml Et2O was
added over a suspension of 2.1 g (55.3 mmol) LiAlH4 in 50 ml Et2O.
After 2 h of stirring the solvent was removed under reduced pres-

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Fig. 8. Thermal ellipsoid representation (30%) of dimeric units in the structure of Dmp(Ph)SbOH (9). The carbon bonded hydrogen atoms were omitted for clarity. Selected
bond lengths (Å) and angles (°): Sb(1A)–O(1A) 1.814(13), Sb(2A)–O(2A) 2.065(5), C(1)–Sb(1A) 2.167(5), C(25)–Sb(1A) 2.217(6), C(31)–Sb(2A) 2.176(5), C(56)–Sb(2A) 2.175(6),
C(1)–Sb(1A)–C(25) 100.1(2), C(1)–Sb(1A)–O(1A) 104.5(4), C(25)–Sb(1A)–O(1A) 88.0(5), C(31)–Sb(2A)–C(56) 100.4(2), C(31)–Sb(2A)–O(2A) 95.9(2), C(56)–Sb(2A)–O(2A)
86.0(2); C(6)–C(1)–Sb(1A)–C(25) 69.2(4), C(36)–C(31)–Sb(2A)–C(56) 69.9(4).
3
sure. Extraction with 300 ml hexane followed by solvent removal
under reduced pressure afforded DmpSbH2 [2]. Yield: 1.99 g
(83%). 1H NMR (200.1 MHz, C6D6): d 2.09 (s, 12H, o-CH3), 2.19 (s,
6H, p-CH3), 2.81 (s, 2H, SbH2), 6.86 (s, 4H, m-Mes), 6.98 (d, 2H,
m-C6H3), 7.20 (t, 1H, p-C6H3).
6.87 (d, 4H, m-Mes), 6.97 (d, 2H, m-C6H3, JHH = 7.4 Hz), 7.21 (t,
1H, p-C6H3, JHH = 7.4 Hz). 13C NMR (90 MHz, C6D6): d ꢁ11.5
3
(SbCH3), 21.5 (o- and p-CH3), 128.3 (m-C6H3), 129.3, 129.6 (m-
Mes), 129.9 (p-C6H3), 135.9, 136.5 (o-Mes), 137.3 (p-Mes), 138.1
(i-C6H3), 149.7 (o-C6H3). MS (EI, 70 eV): 450 (49.4) [M]+, 435
(100) [MꢁMe], 314 (77.5) [Dmp+H]+. IR (nujol, cmꢁ1): 1870 (
mSbH).
4.5. Synthesis of Dmp(Ph)SbH (5)
4.7. Synthesis of DmpSb(SbMe2)2 (7)
A suspension of 1.0 g (1.69 mmol) Dmp(Ph)SbBr in diethyl ether
was added dropwise to 0.2 g (5 mmol) LiAlH4 in diethyl ether
cooled to ꢁ50 °C. After 2 h stirring the solvent was removed in vac-
uum and the solid was extracted with hexane. The removal of the
solvent afforded solid 5. Yield: 0.5 g (60%). 1H NMR (200.1 MHz): d
1.82 (s, 6H, o-CH3), 2.22 (s, 12H, o- and p-CH3), 5.09 (s, 1H, SbH),
6.72, 6.90 (s, 4H, m-Mes), 6.91 (m, 2H, m-Ph), 6.96 (d, 2H, m-
C6H3), 6.98 (m, 1H, p-Ph), 7.18 (t, 1H, p-C6H3), 7.21 (m, 2H, o-Ph).
13C NMR (50.3 MHz): d 21.2 (o-CH3), 21.57, 21.61 (o- and p-CH3),
128.5 (p-Ph), 128.6 (m-C6H3), 128.7 (m-Ph), 129.2, 129.3 (m-
Mes), 129.7 (p-C6H3), 133.3 (i-Ph), 135.6, 137.0 (o-CH3), 137.3 (o-
and p-CH3), 139.7 (i-C6H3), 140.0 (o-Ph), 142.3 (i-Mes), 149.5 (o-
C6H3). MS (FD, positive): 314 (11.7) [DmpH]+, 434 (91.4) [DmpSb]+,
511 (16.6) [Dmp(Ph)Sb]+, 528 (60.4) [Dmp(Ph)SbOH]+. IR (nujol,
0.85 g (2.8 mmol) Me4Sb2 were added via syringe over 0.61 g
(1.4 mmol) DmpSbH2. The reagents were allowed to react at room
temperature for 1 h. The reaction mixture was heated gradually
under reduced pressure up to 90 °C to remove traces of Me4Sb2
and 7 remained. Yield: 0.8 g (77%). 1H NMR (200.1 MHz, C6D6): d
0.78 (s, 6H, Sb–CH3), 0.95 (s, 6H, Sb–CH3), 2.20 (s, 12H, o-CH3),
2.23 (s, 6H, m-CH3), 6.87–6.91 (m, 6H, m-Mes and m-C6H3), 7.16
(dd, 1H, p-C6H3). 13C NMR (50.3 MHz, C6D6): d ꢁ6.5, ꢁ6.9 (Sb–
CH3), 21.2 (p-CH3), 22.3 (o-CH3), 128.2 (m-C6H3), 128.8 (p-C6H3),
129.1 (m-Mes), 134.5 (i-C6H3), 136.0 (o-Mes), 137.2 (p-Mes),
142.9 (i-Mes), 150.2 (o-C6H3). MS (EI, 70 eV): 989 (3.0) [Dmp2Sb3]+,
868 (3.0) [Dmp2Sb2]+, 736 (3.0) [M]+, 585 (7.1) [MꢁSbꢁ3Me]+, 555
(2.8) [DmpSb3]+, 449 (64.2) [Dmp(Me)Sb]+, 434 (81.4) [DmpSb]+,
419 (2.1) [DmpSb]+, 151 (77.9) [Me2Sb]+.
cmꢁ1): 1883 (
mSbH).
4.6. Synthesis of Dmp(Me)SbH (6)
4.8. Formation of {Dmp(Me)Sb}2 (8)
A slurry of 0.35 g (2.5 mmol) MeI and 0.38 g (2.5 mmol) DBU in
50 ml Et2O was added dropwise to solution of 1.1 g (2.5 mmol)
DmpSbH2 in 50 ml Et2O at ꢁ50 °C. The reaction mixture was stir-
red for 1 h at ꢁ50 °C and then was allowed to warm gradually to
room temperature. The solvent was removed in vacuum and the
solid was extracted with 200 ml hexane. After the removal of the
hexane 6 remained. Yield: 1.1 g (90%). 1H NMR (200.1 MHz,
Exposure of a 2% solution of 6 in C6D6 to day light gives 8. Yield:
49%. 1H NMR (360.1 MHz, C6D6): d 0.49 (s, 6H, Sb–CH3), 2.03, 2.07
(s, 6H, o-CH3), 2.20 (s, 12H, p-CH3), 6.77 (d, 4H, m-CH), 6.80 (s, 8H,
m-Mes), 7.06 (s, 2H, p-C6H3). 13C NMR (50.3 MHz, C6D6): d ꢁ7.6
(Sb–CH3), 21.2 (p-CH3), 21.8, 21.9 (o-CH3), 128.3 (p-C6H3), 128.7
(m-C6H3), 128.9 (m-Mes), 136.1, 136.4 (o-CH3), 136.7 (p-Mes),
137.3 (i-C6H3), 141.7 (i-Mes), 149.6 (o-C6H3).
3
C6D6): d 0.45 (d, 3H, Sb–CH3, JHH = 6 Hz), 2.07 (s, 6H, o-CH3),
Crystals of 8 ꢂ C6D6 were grown from a 5% solution of DmpSbH2
3
2.18, 2.19 (s, 12H, o-CH3), 3.31 (q, 1H, SbH, JHH = 6 Hz), 6.84,
and Cp2Ti[C2(Me3Si)2] in a NMR tube.

H.J. Breunig et al. / Journal of Organometallic Chemistry 693 (2008) 2527–2534
2533
Table 1
X-ray diffraction data and structure refinement for 1–3, 5, 8 and 9
1
2
3
5
8 ꢂ C6D6
9
Empirical formula
Formula weight
Crystal system
Space group
a (Å)
C
24H25Br2Sb
C24H25I2Sb
688.99
Monoclinic
P21/c
16.577(3)
16.578(4)
18.086(7)
90
103.94(2)
90
4824(2)
8
1.897
3.710
2608
C30H30BrSb
592.20
Monoclinic
C2/c
39.259(8)
8.6597(17)
15.444(3)
90
91.90(3)
90
5247.7(18)
8
1.499
2.589
2368
C30H31Sb
513.30
Monoclinic
P21/c
8.760(4)
22.311(5)
12.631(3)
90
91.54(4)
90
2467.8(14)
4
1.382
1.132
1048
C56H56D6Sb2
984.59
C30H31OSb
529.30
Monoclinic
P/c
8.9514(18)
22.293(5)
12.636(3)
90
91.00(3)
90
2521.1(9)
4
595.01
Monoclinic
P21/c
17.175(9)
30.507(10)
17.895(5)
90
90.68(3)
90
9376(6)
16
1.686
4.593
Triclinic
ꢀ
P1
12.127(5)
14.102(3)
15.315(4)
102.370(10)
109.43(2)
98.43(2)
2344.1(12)
2
1.386
1.188
1000
0.6 ꢀ 0.4 ꢀ 0.2
2.64–27.50
15, 17, 19
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Volume (Å3)
Z
Calculated density (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
1.394
1.113
1080
)
4640
Crystal size (mm3)
h range for data collection (°)
Index ranges (h,k,l)
0.7 ꢀ 0.5 ꢀ 0.3
2.13–25.01
ꢁ19/20,ꢁ11/
36, 21
0.9 ꢀ 0.3 ꢀ 0.3
2.53–27.51
ꢁ21/14,ꢁ9/21, 23
0.5 ꢀ 0.4 ꢀ 0.3
2.41–24.99
46, 10, 18
0.9 ꢀ 0.3 ꢀ 0.1
2.94–25.01
ꢁ8/10,ꢁ26/
14, 15
0.5 ꢀ 0.4 ꢀ 0.3
2.44–26.08
11, 27, 15
Reflections collected/unique
19040/16282
[0.0707]
98.4 [25.01]
0.3395 and 0.1413
13249/11074
[0.0381]
99.7 [27.51]
0.4024 and 0.1351
16992/4260
[0.089.6]
92.3 [24.99]
0.5105 and 0.3576
5616/4331
[0.0457]
99.6 [25.01]
0.8952 and
0.4290
12341/10636
[0.0275]
98.8 [27.50]
0.7971 and 0.5359
25385/9531
[0.0622]
96.0 [26.08]
0.7312 and 0.6060
[R(int)
]
Completeness to h [h] (%)
Maximum and minimum
transmission
Data/restraints/parameters
16282/0/998
1.013
11074/0/499
1.066
4260/0/304
1.081
4331/0/290
0.956
10636/0/547
1.020
9531/14/616
0.949
Goodness-of-fit on F2
Final R indices (I > 2
R indices (all data) (R1, wR2)
r
(I)) (R1, wR2)
0.0624, 0.1346
0.1199, 0.1611
0.948 and ꢁ1.079
0.0699, 0.1839
0.0973, 0.1988
3.381 and ꢁ3.197
0.0658, 0.1734
0.1025, 0.1877
2.790 and ꢁ1.067
0.0662, 0.1427
0.1303, 0.1653
0.803 and ꢁ1.674
0.0453, 0.1006
0.0691, 0.1103
0.801 and ꢁ1.131
0.0389, 0.0832
0.0585, 0.0906
0.428 and ꢁ0.541
Largest difference peak and hole
(e ꢂ Åꢁ3
)
4.9. Synthesis of Dmp(Ph)SbOH (9)
the final structure factors are considerably better for the solution
obtained in the P/c space group (R1 = 0.0389, wR2 = 0.0832 (P/c)
vs. R1 = 0.1258, wR2 = 0.2428 (P21/c)). In both solutions with differ-
ent space groups there is a disorder involving the antimony atoms
and the hydroxyl groups. In the P/c space group the antimony
atoms of the two crystallographically independent molecules can
be located on two positions and were refined using free variables.
They belong to the two isomers (R and S). The oxygen atoms suffer
the same type of disorder and they were refined in an analogous
way. The oxygen atoms O1B O2B were constrained to be isotropic
(see Table 1).
14.6 g (20 mmol) 3 in 50 ml toluene were flushed over a chro-
matography column (19 cm ꢀ 2.5 cm, Al2O3, activity level 2). Two
fractions of 50 and 100 ml were eluted with toluene. Removal of
the solvent from the second fraction gave crystals of 9. Yield:
2.0 g (19.3%), m.p. 161–164 °C. 1H NMR (360.1 MHz): d 1.91, 2.15
(s, 12H, o-CH3), 2.13 (s, 6H, p-CH3), 6.70, 6.79 (m, 4H, m-Mes),
6.85 (s, 2H, m-C6H3), 7.03 (m, 1H, p-Ph), 7.05 (m, 2H, m-Ph), 7.15
(t, 1H, p-C6H3), 7.24 (m, 2H, o-Ph). 13C NMR (50.3 MHz, C6D6): d
21.11 (p-CH3), 21.11, 21.37 (o-CH3), 128.89, 129.08 (m-Mes),
129.60 (m-C6H3), 129.60 (p-C6H3), 133.79 (o-Ph), 136.51, 136.89
(o-Mes), 137.60 (p-Mes), 138.29 (i-Mes), 146.50 (i-C6H3), 147.55
(o-C6H3). MS (CI, positive): 528 (52.7) [M]+, 511 (100) [MꢁOH]+,
314 (40.9) [Dmp+H]+, 78 (9.1) [Ph+H]+. MS (CI, negative): 527
(11.7) [MꢁH]ꢁ, 511 (14.0) [MꢁOH]ꢁ, 214 (100) [PhSbO]ꢁ. Anal.
Calc. for C30H31OSb (529.32): C, 68.07; H, 5.90. Found C, 67.91; H,
6.10%.
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft for financial
support. We thank Dipl. Ing. J. Stelten for the 2D NMR spectra
acquisition and analysis and Dr. T.Dülcks and Dipl. Ing. D. Kemken
for the mass spectra measurements.
Appendix A. Supplementary material
4.10. X-ray structure determinations
CCDC 678179, 678177, 678175, 678178, 678174 and 678176
contain the supplementary crystallographic data for 1, 2, 3, 5, 8
and 9. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/da-
ta_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.
jorganchem.2008.04.038.
The data for X-ray structure analysis were collected on a Sie-
mens P4 four-circle (1, 2, 5, 7) or STOE-IPDS (3, 9) diffractometer
using graphite-monochromated Mo K
a radiation (k = 0.71073 Å).
For this purpose the crystals were attached with Kel-F oil to a glass
fibre and cooled in a nitrogen stream to 173 K. The structures were
solved by Patterson methods [20], or direct methods [21]. All non-
hydrogen atoms were refined with anisotropic thermal parame-
ters. For structure solving and refinement the software package
WINGX was used [22]. The drawings were created using Diamond.
The hydrogen atoms were calculated in riding positions. The
hydrogen atom directly attached to antimony in 5 was refined iso-
tropically without any constraints. The structure of 9 was solved
and refined in the space group P/c although the systematic ab-
sences indicate that P21/c is the correct space group. However,
References
[1] B. Twamley, C.D. Sofield, M.M. Olmstead, P.P. Power, J. Am. Chem. Soc. 121
(1999) 3357–3367.
[2] R. Waterman, T.D. Tilley, Angew. Chem. 118 (2006) 2992–2995;
R. Waterman, T.D. Tilley, Angew. Chem. Int. Ed. 45 (2006) 2926–2929.

2534
H.J. Breunig et al. / Journal of Organometallic Chemistry 693 (2008) 2527–2534
[3] B. Twamley, C.-S. Hwang, N.J. Hardman, P.P. Power, J. Organomet. Chem. 609
(2000) 152–160.
[12] O. Mundt, G. Becker, H. Stadelmann, H. Thurn, Z. Anorg. Allg. Chem. 617 (1992)
59–71.
[4] J. Beckmann, T. Heek, M. Takahashi, Organometallics 26 (2007) 3633–
3635.
[5] E. Urnezius, K.-C. Lam, A.L. Rheingold, J.D. Protasiewicz, J. Organomet. Chem.
630 (2001) 193–197.
[6] L. Balázs, H.J. Breunig, Coord. Chem. Rev. 248 (2004) 603–621.
[7] H.J. Breunig, I. Ghesner, M. Ghesner, E. Lork, Inorg. Chem. 42 (2003) 1751–
1757.
[13] H.J. Breunig, M. Denker, K.H. Ebert, J. Organomet. Chem. 470 (1994) 87–92.
[14] H.J. Breunig, K.H. Ebert, S. Gülec, M. Dräger, D.B. Sowerby, M.J. Begley, U.
Behrens, J. Organomet. Chem. 427 (1992) 39–48.
[15] P.L. Millington, D.B. Sowerby, J. Organomet. Chem. 480 (1994) 227–234.
[16] A. Bondi, J. Phys. Chem. 68 (1964) 441–451.
[17] G. Balázs, H.J. Breunig, E. Lork, W. Offermann, Organometallics 20 (2001)
2666–2668.
[8] R.P. Wagner, Dissertation, Universität Bremen, 2007.
[9] U. Rosenthal, V.V. Burlakov, P. Arndt, W. Baumann, A. Spannenberg,
Organometallics 22 (2003) 884–900.
[10] K. Issleib, B. Hamann, Z. Anorg. Allg. Chem. 343 (1966) 196–203.
[11] H. Schmidbaur, J.M. Wallis, R. Nowak, B. Huber, G. Müller, Chem. Ber. 120
(1987) 1837–1843.
[18] H.J. Breunig, T. Krüger, E. Lork, J. Organomet. Chem. 648 (2002) 209–213.
[19] J.J. Ellison, P.P. Power, J. Organomet. Chem. 526 (1996) 263–267.
[20] G.M. Sheldrick, Z. Dauter, K.S. Wilson, H. Hope, L.C. Sieker, Acta Crystallogr.
Sect. D 49 (1993) 18–23.
[21] G.M. Sheldrick, Acta Crystallogr. Sect. A 46 (1990) 467–473.
[22] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837–838.