Synthesis, structure, and reaction of tricoordinate stibine and tetracoordinate stiboranide

Article abstract of DOI:10.1016/j.jorganchem.2009.12.009

Tricoordinate stibine 1 and tetracoordinate stiboranide 2a were synthesized by utilizing SbCl₃. The structure of 2a was confirmed by X-ray analysis. The interconversion between 1 and 2 could be achieved by BrNEt₄ and NaH or BuLi. The

Full text of DOI:10.1016/j.jorganchem.2009.12.009

Journal of Organometallic Chemistry 695 (2010) 740–746
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, structure, and reaction of tricoordinate stibine and tetracoordinate
stiboranide
b,1
Xin-Dong Jiang a, , Yohsuke Yamamoto
*
a The Key Laboratory for Special Functional Materials Ministry of Education, Henan University, Kaifeng, Henan 475-004, China
b Department of Chemistry, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Tricoordinate stibine 1 and tetracoordinate stiboranide 2a were synthesized by utilizing SbCl3. The struc-
ture of 2a was confirmed by X-ray analysis. The interconversion between 1 and 2 could be achieved by
BrNEt4 and NaH or BuLi. The pentacoordinate apicophilic stiborane 6 was prepared from 1. Due to steric
repulsion between the TIP group and the aromatic ring, the C1–Sb–C2 angle of 6b was narrowed by 4.4°
compared to that of 6a by X-ray analysis.
Received 14 November 2009
Received in revised form 4 December 2009
Accepted 11 December 2009
Available online 16 December 2009
Ó 2009 Elsevier B.V. All rights reserved.
Keywords:
Berry pseudorotation
Apicophilic
Stiboranide
Stiborane
Isomerization
1. Introduction
et al. [14,15] has been calculated to be higher in energy than
BPR (calculated to be ꢀ 10 kcal molꢁ1 for TR of PH5) [16–18].
Hypervalent compounds of the main group elements have been
attractive subjects for both experimental and theoretical chemists
for a long time [1]. Especially, hypervalent phosphorus chemistry
[2–4], which is deeply related to the phosphoryl transfer reaction
in biological systems [5–9], has elucidated the significant funda-
mental properties of pentacoordinated molecules. Pentacoordinate
compounds are discovered to have two different structures, one is
trigonal bipyramid (TBP) structure and the other is square pyramid
(SP) structure, and the former is generally preferred (Fig. 1). The
TBP structure includes two distinct bonds, apical bond and equato-
rial bond. The apical bond is described as a three-center-four-elec-
tron (hypervalent) bond, whereas the equatorial bond is described
as an sp2 bond. The apical bond comprising of the two sites posi-
tioned linearly with the center intersects the equatorial plane
perpendicularly.
Therefore, usually TR is not taken into consideration in discus-
sions on the isomerization of pentacoordinate molecules. The
motion of BPR is illustrated in Fig. 2 where one of the equatorial
ligands is taken as a pivot (3) and the originally apical bonds (1,
2) undergo an angular bending from 180° to 120°, and two equa-
torial ligands (4, 5) bend from 120° to 180° in equatorial plane
including the pivot ligand. In this process, an SP structure is
the transition state.
In the TBP structure, electronegative and sterically small groups
generally prefer to occupy the apical sites, whereas electron-donat-
ing and bulky ligands prefer the equatorial sites. The relative pref-
erence of substituent occupying the apical site is particularly
known as apicophilicity [19–36]. From many experimental sys-
tems and theoretical calculations, an oxygen atom is determined
to be much more apicophilic than a carbon atom [19–36]. Anti-
apicophilic compound, which violates relative apicophilicity of
the elements, generally has high energy and is unstable, thus easily
isomerizes into its stable apicophilic compound.
Using Martin ligand [37] and new bidentate ligand with two
C2F5 groups [38], synthesis, structure, and reaction of pentacoordi-
nate compounds in the central atom of phosphorus and arsenic had
been reported [20,38–43]. Herein, we now report the synthesis of
tricoordinate stibine 1 and a unique tetracoordinate stiboranide
2a bearing new bidentate ligand. The reactivity of 1 and 2 are
investigated. Synthesis and structure of the pentacoordinate stibo-
rane are then discussed.
A very rapid nondissociative intramolecular exchange of sites,
i.e., the exchange between the apical ligand and the equatorial
ligand, is usually advocated by Berry pseudorotation (BPR) [10–
12], which is presumed to be a very low energy process (calcu-
lated to be ꢀ 2 kcal molꢁ1 for BPR of PH5) [13]. Another alterna-
tive mechanism called turnstile rotation (TR) proposed by Ugi
* Corresponding author. Tel./fax: +86 0378 3881358.
E-mail addresses: xdjiang@henu.edu.cn (X.-D. Jiang), yyama@sci.hiroshima-u.
ac.jp (Y. Yamamoto).
1
Tel.: +81 082 4247430; fax: +81 082 4240723.
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.12.009

X.-D. Jiang, Y. Yamamoto / Journal of Organometallic Chemistry 695 (2010) 740–746
741
gen signals for two aromatic rings in the 1H NMR spectrum
(d = 8.23 (dd, 2H, 3JH–H = 7.6 Hz, 4JH–H = 1.7 Hz), 7.82 (td, 1H, 3JH–H
=
=
=
4
3
4
7.6 Hz, JH–H = 1.7 Hz), and 7.79 (td, 1H, JH–H = 7.6 Hz, JH–H
3
1.7 Hz) ppm; d = 7.97–8.01 (m, 2H), and 7.80 (t, 2H, JH–H
7.6 Hz) ppm), and the two aromatic rings were unequivalent. This
showed that compound 1 was a tricoordinate stibine and com-
pared with arsenic analogue similarly to our previous result [43].
In comparison with compound 2a in the 1H NMR spectrum
3
3
(d = 7.79 (d, 2H, JH–H = 8 Hz), 7.61 (br d, 2H, JH–H = 8 Hz), 7.42
3
4
3
(td, 2H, JH–H = 8 Hz, JH–H = 1.5 Hz), and 7.32 (td, 2H, JH–H = 8 Hz,
4JH–H = 1.5 Hz) ppm at 25 °C), two aromatic rings were equivalent.
Furthermore, the 19F NMR spectrum of CF3 groups in 2a showed
sharp signal, in which all CF3 groups were magnetically equivalent.
The solid-state structure of stiboranide 2a was confirmed by the X-
ray crystallographic analysis (Fig. 3 and Table 1). The bond length
of Sb1–O1 and Sb1–O2 was same, which was 2.188(6) Å. The mol-
ecule of compound 2a was symmetrical by the central atom of
antimony, therefore the 1H NMR spectrum of two aromatic rings
was same and in agreement with that described above. Compound
2a was stable in air and water.
Fig. 1. Trigonal bipyramid and square pyramid.
2. Result and discussion
2.1. Synthesis and structure of 1 and 2a
Dianion 3 [38] was added to a solution of SbCl3 in THF to give
tricoordinate stibine 1 (8%) and tetracoordinate stiboranide 2a
(7%) (Scheme 1). Compound 1 showed two sets of distinct hydro-
Scheme 1. Synthesis of 1 and 2a.
Fig. 2. The motion of BPR.
Fig. 3. The ORTEP drawings of 2a and 4 showing the thermal ellipsoids at the 30% probability level. The hydrogen atoms are omitted for clarity.

742
X.-D. Jiang, Y. Yamamoto / Journal of Organometallic Chemistry 695 (2010) 740–746
2.2. Interconversion between 1 and 2
HCl, 1 was not obtained at all. 2a may be stabilized by coordination
of the lithium cation with the two oxygen atoms of the apical bond
in solution. By using BrNEt4, the reaction of 2a gave LiBr and the
lithium cation could be removed from 2a. In contrast, 2 was easily
prepared by the reaction of 1 in the presence of NaH or BuLi. To the
best of our knowledge, the interconversion between tricoordinate
stibine and tetracoordinate stiboranide was a first example.
The interconversion between 1 and 2 was investigated. Under
air, after BrNEt4 was added to a solution of 2a in acetone and the
reaction was quenched with 6 M HCl, 2a was almost quantitatively
converted into 1 (Scheme 2). When 2a was only quenched with
Table 1
Selected bond lengths (Å) and angles (°) for the 2a and 4.
2.3. Reactivity of 1 and 2a to MeI
2a
4
Bond lengths (Å)
Sb1–O1
Sb1–O2
Sb1–C1
Sb1–C2
The ability of ER3 (E = As, Sb, Bi) to act as Lewis base has long
been recognized. Such compounds arise from the donation of the
lone pair of electrons on the E atom to an electrophile. Therefore,
the reaction of 1 with MeI was carried out (Fig. 4). The expected re-
sult of methylstiborane 4 was not obtained. On the contrary, the
reaction of 2a with MeI gave stiborane 4 in 40% yield by SN2 reac-
tion (Fig. 4). The structure of 4 was confirmed by X-ray analysis
(Fig. 3 and Table 1). The lone pair of electrons of 1 were sited in
an sp3 orbital; the structure of tetracoordinate stiboranide 2a
was a trigonal bipyramid structure, and the lone pair of electrons
were sited in an sp2 orbital. It is well known that the higher the en-
ergy of the lone pair is, the more reactive the compound is [44].
Therefore, the reactivity of the lone pair in sp3 orbital of 1 should
be higher than that in sp2 orbital of 2a, which was not in agreement
with our experimental result. This could be explained in terms of
the steric repulsion of the C2F5 group. The experimental result that
compound 1 did not react with MeI showed that the steric bulk of
the pentafluoroethyl group could prevent the lone pair from
attacking MeI. This result was similar to the reported result
[42,45]. On the other hand, for compound 2a, the lone pair was si-
ted in sp2 orbital in the equatorial plane, and could react with MeI
to give compound 4.
2.188(6)
2.188(6)
2.160(8)
2.149(8)
2.069(4)
2.069(4)
2.097(4)
2.097(4)
2.088(8)
Sb1–C3
Bond angles (°)
O1–Sb1–O2
O1–Sb1–C1
O1–Sb1–C2
O1–Sb1–C3
O2–Sb1–C1
O2–Sb1–C2
O2–Sb1–C3
C1–Sb1–C2
C1–Sb1–C3
C2–Sb1–C3
156.1(3)
76.5(4)
89.5(3)
168.1(2)
80.70(16)
94.08(17)
95.97(10)
94.08(17)
80.70(16)
95.97(10)
128.5(2)
90.4(4)
76.2(3)
110.3(4)
115.75(12)
115.75(13)
2.4. Preparation of pentacoordinate apicophilic stiborane 6 from 1
Using new bidentate ligand with two C2F5 groups, the pentaco-
ordinate anti-apicophilic phosphoranes were successfully isolated
by the reaction of P–H compound with RLi (R = alkyl, aryl) and I2
Scheme 2. Interconversion between 1 and 2.
Fig. 4. The reaction of 1 and 2a with MeI.
Scheme 3. Synthesis of pentacoordinate phosphoranes.

X.-D. Jiang, Y. Yamamoto / Journal of Organometallic Chemistry 695 (2010) 740–746
743
Scheme 4. Synthesis and isomerization of pencoordinate stiborane 6.
Fig. 5. 19F NMR spectra of 6a and 7 in THF.
which acted as oxidative cyclization (Scheme 3) [38,42]. The anti-
apicophilic compounds could quantitatively convert into the
corresponding apicophilic compounds by heat in solution [38,42].
Furthermore, the kinetic study revealed that the steric hindrance
of the C2F5 group was more effective for freezing pseudorotation
[38,42]. This enables us to investigate synthesis and isolation of
anti-apicophilic stiborane 5a. Using our method for the synthesis
of the pentacoordinate compounds [40], only the corresponding
apicophilic stiborane 6a was obtained in 50% yield, though the
monodentate ligand was the t-butyl group which was effective
for slowing the isomerization (Scheme 4). In order to trace the
isomerization of 5a to 6a, the samples of two NMR tubes were pre-
pared: after t-BuLi was added to compound 1 in THF, the superna-
tant was transferred to an NMR tube under N2 (NMR1); after I2 was
added to the mixture, another NMR tube (NMR2) was prepared in
the same condition. The reaction was monitored by 19F NMR
(Fig. 5). In NMR1 spectrum, the dianion 7 which have four distinct
fluorine singles corresponding to CF3 groups (d = ꢁ77.5, ꢁ77.9,
ꢁ78.4, and ꢁ78.7 ppm at 25 °C) was observed. The NMR2 spectrum
showed that the anti-apicophilic compound 5a would be generated
by dianion 7 just after the addition of I2 and rapidly isomerized into
its corresponding stable stiborane 6a by BPR, and compound 5a
was not observed at all. Therefore, the activation free energy for
the isomerization of 5a to 6a was not enough higher to achieve
the isolation of 5a. By the steric hindrance of the monodentate li-
gand, TIP (triisopropylphenyl) was employed [46]. The same result
of the apicophilic stiborane 6b was given in 61% yield. The struc-
tures of 6a and 6b were confirmed by X-ray analysis (Fig. 6 and
Table 2), which show that all the structures have TBP geometry.
The C1–Sb–C2 angle of 6b (123.63°) was narrowed by 4.4°
Table 2
Selected bond lengths (Å) and angles (°) for the 6a and 6b.
6a
6b
Bond lengths (Å)
Sb1–O1
Sb1–O2
Sb1–C1
Sb1–C2
2.070(3)
2.073(3)
2.101(4)
2.099(4)
2.182(4)
2.0630(19)
2.0666(19)
2.107(3)
2.108(3)
2.122(3)
Sb1–C3
Bond angles (°)
O1–Sb1–O2
O1–Sb1–C1
O1–Sb1–C2
O1–Sb1–C3
O2–Sb1–C1
O2–Sb1–C2
O2–Sb1–C3
C1–Sb1–C2
C1–Sb1–C3
C2–Sb1–C3
161.53(12)
79.69(12)
91.44(14)
98.96(15)
92.63(13)
80.04(14)
99.96(15)
128.07(14)
117.19(18)
114.72(18)
167.62(8)
80.65(10)
93.99(10)
95.16(9)
93.13(10)
80.49(10)
97.20(9)
123.63(10)
116.61(11)
119.76(10)

744
X.-D. Jiang, Y. Yamamoto / Journal of Organometallic Chemistry 695 (2010) 740–746
Fig. 6. The ORTEP drawings of stiboranes (6a and 6b) showing the thermal ellipsoids at the 30% probability level. The hydrogen atoms are omitted for clarity.
compared to that of 6a (128.07°). This was due to steric repulsion
between the TIP group and the aromatic ring. To isolate anti-apic-
ophilic stiborane, a bulky bidentate ligand or a bulky monodentate
ligand should be necessary.
4.2. Preparation of 1 and 2a
Under N2, dianion 3 [38] (1.23 mmol) which was prepared from
the reaction of 1,1,1,3,3,3-hexafluro-2-(2-bromophenyl)-2-propa-
nol (532 mg, 1.23 mmol) with t-BuLi (in 1.57 M pentane, 1.6 mL,
2.51 mmol) in the presence of excess NaH was added to a solution
of SbCl3 (143 mg, 0.614 mmol) in THF (3 mL) at ꢁ78 °C and stirred
for 0.5 h. The mixture was warmed to room temperature and stir-
red for 3 h. The reaction was quenched with distilled water
(50 mL ꢂ 2). The mixture was extracted with ether (80 mL ꢂ 2),
and dried over anhydrous MgSO4. After solvent removal by evapo-
ration, the resulting crude product was separated by column chro-
matography (CH3COOC2H5), followed by reversed-phase HPLC
(CH3CN) to afford 1 (RT = 14.4 min, 38.5 mg, 0.048 mmol, 8%) and
2a (RT = 13.6 min, 33.3 mg, 0.041 mmol, 7%) as white solids. Color-
less crystals of 2a suitable for X-ray analysis were obtained by
recrystallization from THF/Et2O. 1: 1H NMR (CDCl3) d 8.23 (dd,
3. Conclusion
Tricoordinate stibine 1 and tetracoordinate stiboranide 2a were
synthesized by the reaction of dianion 3 with SbCl3. The structure
of tetracoordinate stiboranide 2a was confirmed by X-ray analysis.
The interconversion between 1 and 2 was achieved by BrNEt4 and
NaH or BuLi. No reaction of 1 with MeI gave an example of the ste-
ric bulk of the pentafluoroethyl group to prevent the lone pair from
attacking an electrophile. The pentacoordinate anti-apicophilic
stiborane 5 was not successfully isolated and the corresponding
apicophilic stiborane 6 was obtained from 1. Due to steric repul-
sion between the TIP group and the aromatic ring, the C1–Sb–C2
angle of 6b was narrowed by 4.4° compared to that of 6a by X-
ray analysis. Those researches of isolating anti-apicophilic stibora-
ne are now ongoing.
3
4
2H, JH–H = 7.6 Hz, JH–H = 1.7 Hz), 7.97–8.01 (m, 2H), 7.82 (td, 1H,
3JH–H = 7.6 Hz, JH–H = 1.7 Hz), 7.80 (t, 2H, JH–H = 7.6 Hz), 7.79 (td,
4
3
3
4
1H, JH–H = 7.6 Hz, JH–H = 1.7 Hz); 19F NMR (CDCl3) d ꢁ78.17 (t,
5
3
6F, JF–F = 4.9 Hz), ꢁ78.24 (d, 6F, JF–F = 12.3 Hz), ꢁ115.9 (dq, 2F,
2JF–F = 283 Hz, 3JF–F = 12.3 Hz), ꢁ116.8 (s, 4F), ꢁ119.8 (dq, 2F, 2JF–F
=
=
4. Experimental
283 Hz, JF–F = 4.9 Hz). 2a: 1H NMR (CDCl3) d 7.79 (d, 2H, JH–H
5
3
3
3
8 Hz), 7.61 (br d, 2H, JH–H = 8 Hz), 7.42 (td, 2H, JH–H = 8 Hz,
4.1. General procedures
4JH–H = 1.5 Hz), 7.32 (td, 2H, JH–H = 8 Hz, JH–H = 1.5 Hz); 19F NMR
3
4
2
(CDCl3) d ꢁ78.2 (s, 12F), ꢁ114.8 (d, 2F, JF–F = 290 Hz), ꢁ116.7 (d,
Melting points were measured using a Yanaco micro melting
point apparatus. 1H NMR (400 MHz), 19F NMR (376 MHz), 31P
NMR (162 MHz) were recorded using JEOL EX-400 or JEOL AL-
400 spectrometers. 1H NMR chemical shifts (d) are given in ppm
downfield from Me4Si, determined by residual chloroform (d =
7.26 ppm). 19F NMR chemical shifts are given in ppm downfield
from external CFCl3. 31P NMR chemical shifts are given in ppm
downfield from external 85% H3PO4. Elemental analyses were per-
formed using a Perkin–Elmer 2400 CHN elemental analyzer. Tetra-
hydrofuran (THF) and diethyl ether (Et2O) were freshly distilled
from Na/benzophenone, n-hexane was distilled from Na, and other
solvents were distilled from CaH2. Merck silica gel 60 was used for
the column chromatography.
2
2F, JF–F = 290 Hz), ꢁ119.2 (s, 4F).
4.3. Interconversion of 2a to 1
Under air, BrNEt4 (26 mg, 0.124 mmol) was added to a solution
of 2a (33.3 mg, 0.0413 mmol) in acetone (10 mL) at room temper-
ature. The mixture was stirred for 16 h at room temperature. The
reaction was quenched with 6 M HCl (50 mL). The mixture was ex-
tracted with ether (60 mL ꢂ 2), and dried over anhydrous MgSO4.
After solvent removal by evaporation, the resulting crude was sep-
arated by preparative TLC (n-hexane/CH2Cl2 = 4:1) to afford 1

X.-D. Jiang, Y. Yamamoto / Journal of Organometallic Chemistry 695 (2010) 740–746
745
Table 3
Crystallographic data for 2a, 4, 6a and 6b.
Compound
2aꢃ(2THFꢃ2H2OꢃEt2O)
4
6a
6b
Formula
C34H38F20LiO7Sb
1067.33
Orthorhombic
Pbca
Colorless
Plate
C23H11F20O2Sb
821.07
Monoclinic
P2/c
Colorless
Plate
C26H17F20O2Sb
863.15
Orthorhombic
Pbca
Colorless
Plate
C37H31F20O2Sb
1009.37
Monoclinic
P21/c
Colorless
Plate
Molecular weight
Crystal system
Space group
Color
Habit
Crystal dimensions (mm)
a (Å)
b (Å)
0.30, 0.20, 0.10
18.6260(5)
21.6460(7)
22.2110(6)
90
0.25, 0.20, 0.15
22.3180(6)
11.8360(3)
10.4360(3)
90
0.40, 0.40, 0.30
11.9550(2)
28.0850(5)
18.1130(2)
90
0.60, 0.50, 0.40
14.9670(2)
10.39900(10)
26.0680(3)
90
c (Å)
a
(°)
b (°)
90
90
8955.0(4)
8
1.583
98.3080(10)
90
2727.80(13)
4
1.999
1.171
90
90
102.6910(10)
90
3958.15(8)
4
1.694
0.825
c
(°)
V (Å3)
6081.55(16)
8
1.885
1.056
3360
Z
Dcalc (g cmꢁ3
)
Absolute coefficient (mmꢁ1
F(0 0 0)
)
0.741
4256
1584
2000
Radiation: k (Å)
Temperature (°C)
Data collected
Mo K
25
+h, k,
a
, 0.71073
Mo K
20
+h, +k,
a
, 0.71073
Mo K
20
+h, +k,
a
, 0.71073
Mo Ka, 0.71073
ꢁ100
l
l
l
+h, +k, l
Data/restrains/parameters
R1 (I > 2r(I))
10379/0/493
0.1120
3283/0/207
0.0640
6200/0/446
0.0474
7447/0/547
0.0393
wR2 (all data)
0.3543
0.1900
0.1534
0.1405
Goodness-of-fit
1.092
0.982, ꢁ2.156
1.092
0.745, ꢁ2.255
1.123
0.951, ꢁ2.116
1.208
0.982, ꢁ2.156
Largest difference in peak, hole (e Åꢁ3
)
4
3
4
(32.5 mg, 0.0402 mmol, 97%). The spectral data of 1 were consis-
tent with those of the same product described above.
3JH–H = 8 Hz, JH–H = 1.2 Hz), 7.68 (td, 2H, JH–H = 8 Hz, JH–H
=
1.2 Hz), 1.72 (s, 3H); 19F NMR (CDCl3) d ꢁ78.2 (s, 6F), ꢁ78.4 (dd,
3
5
2
6F, JF–F = 14.8 Hz, JF–F = 6.1 Hz), ꢁ115.8 (dq, 2F, JF–F = 283 Hz,
3JF–F = 14.8 Hz), ꢁ116.1 (d, 2F, JF–F = 283 Hz), ꢁ117.2 (br d, 2F,
2
4.4. Interconversion of 1 to 2
2JF–F = 283 Hz), ꢁ119.9 (dq, 2F, JF–F = 283 Hz, JF–F = 6.1 Hz). MS
2
5
(EI(+)): m/z = 806[M]+, 687[MꢁC2F5]+.
Method 1: under N2, a solution of 1 (22.5 mg, 0.027 mmol) in
THF (3 mL) was added to a suspension of NaH (40 mg, 1.0 mmol)
in THF (2 mL) at 0 °C. The mixture was stirred for 1 h at room
temperature. The reaction was quenched with distilled water
(50 mL ꢂ 2). The mixture was extracted with ether (70 mL ꢂ 2),
and dried over anhydrous MgSO4. After solvent removal by evapo-
ration, the mixture of 1 and 2b (24 mg) was obtained. The 1H NMR
(CDCl3) showed the signals for 1 and 2b with the ratio of 1/
2b = 21:79. The spectral data of 2b were consistent with those of
the product 2a described above.
Method 2: under N2, n-BuLi (in 1.59 M n-hexane, 0.02 mL,
0.031 mmol) was added to a solution of 1 (24.2 mg, 0.03 mmol)
in Et2O (1.5 mL) at 0 °C and stirred for 0.5 h at the same tempera-
ture. The mixture was warmed to room temperature and stirred for
3 h. The reaction was quenched with distilled water (60 mL ꢂ 2).
The mixture was extracted with ether (50 mL ꢂ 2), and dried over
anhydrous MgSO4. After solvent removal by evaporation, the mix-
ture of 1 and 2a (20 mg) was obtained. The 1H NMR (CDCl3)
showed the signals for 1 and 2a with the ratio of 1/2a = 40:60.
The spectral data of 2a were consistent with those of the same
product described above.
4.6. Preparation of [TBPY-5-11]-1-t-butyl-3,3,30,30-
tetrakis(pentafluoroethyl)-1,10-spirobi [3H,2,1,5-benzoxastibole] (6a)
Under N2, a solution of 1 (31.3 mg, 0.038 mmol) in THF (1 mL)
was added to a suspension of NaH (41.6 mg, 1.04 mmol) in THF
(1 mL) at 0 °C and the mixture was stirred for 10 min at room tem-
perature. The mixture was then cooled at ꢁ78 °C, and t-BuLi (in
1.57 M n-pentane, 0.030 mL, 0.047 mmol) was added. The mixture
was then stirred for 15 min at room temperature. I2 (12 mg,
0.047 mmol) was added to the mixture at ꢁ78 °C and stirred for
1 h at 0 °C. The reaction was quenched with aqueous Na2S2O3
(30 mL ꢂ 2). The mixture was extracted with Et2O (30 mL ꢂ 2),
and the organic layer was washed with brine (20 mL ꢂ 2) and dried
over anhydrous MgSO4. After removing the solvents by evapora-
tion, the resulting crude was separated by TLC (n-hexane/
CH2Cl2 = 4:1) to afford 6a (16.8 mg, 0.019 mmol, 50%) as a white
solid. Colorless crystals of 6a suitable for X-ray analysis were ob-
tained by recrystallization from n-hexane/CH2Cl2. 1H NMR (CDCl3)
3
3
d 8.08 (d, 2H, JH–H = 8 Hz), 7.83 (br d, 2H, JH–H = 8 Hz), 7.68 (td,
3
4
3
4
2H, JH–H = 8 Hz, JH–H = 1.2 Hz), 7.63 (td, 2H, JH–H = 8 Hz, JH–H
=
=
=
1.2 Hz), 1.39 (s, 9H); 19F NMR (CDCl3) d ꢁ78.3 (dd, 6F, JF–F
3
4.5. Preparation of [TBPY-5-11]-methyl-3,3,30,30-
5
2
tetrakis(pentafluoroethyl)-1,10-spirobi [3H,2,1,5-benzoxastibole] (4)
14.8 Hz, JF–F = 4.9 Hz), ꢁ78.4 (br s, 6F), ꢁ113.2 (dq, 2F, JF–F
3
2
285 Hz, JF–F = 14.8 Hz), ꢁ114.1 (br d, 2F, JF–F = 285 Hz), ꢁ115.3
2
2
5
(d, 2F, JF–F = 285 Hz), ꢁ118.6 (dq, 2F, JF–F = 285 Hz, JF–F
=
Under N2, MeI (0.01 mL, 0.16 mmol) was added to a solution of
2a (37.3 mg, 0.035 mmol) at 0 °C. The mixture was stirred for 6 h at
room temperature. The mixture was extracted with ether (80 mL
ꢂ 2), and the organic layer was washed with brine (60 mL ꢂ 2)
and dried over anhydrous MgSO4. After solvent removal by evapo-
ration, the resulting crude was separated by TLC (n-hexane/
CH2Cl2 = 4:1) to afford 4 (11.2 mg, 0.0136 mmol, 40%). Colorless
crystals of 4 suitable for X-ray analysis were obtained by recrystal-
lization from n-hexane/CH2Cl2. 1H NMR (CDCl3) d 8.14 (d, 2H,
4.9 Hz). Anal. Calc. for C26H17F20O2Sb: C, 36.18; H, 1.90. Found: C,
36.45; H, 1.80%.
4.7. Preparation of [TBPY-5-11]-1-TIP-3,3,30,30-
tetrakis(pentafluoroethyl)-1,10-spirobi [3H,2,1,5-benzoxastibole] (6b)
Under N2, triisopropylphenyllithium (0.689 mmol) which was
prepared from the reaction of 1-bromo-2,4,6-triisopropylbenzene
(195.3 mg, 0.689 mmol) with n-BuLi (in 1.58 M n-hexane, 0.43 mL,
3
3JH–H = 8 Hz), 7.86 (br d, 2H, JH–H = 8 Hz), 7.72 (td, 2H,

746
X.-D. Jiang, Y. Yamamoto / Journal of Organometallic Chemistry 695 (2010) 740–746
[2] R.R. Homes, Pentacoordinated Phosphorus-Structure and Spectroscopy ACS
Monograph 175 and 176, vol. I and II, American Chemical Society, Washington,
DC, 1980.
[3] D.E.C. Corbridge, Phosphorus: An Outline of its Chemistry, Biochemistry and
Technology, fourth ed., Elsevier, Amsterdam, 1990 (Chapter 14).
[4] R. Burgada, R. Setton, in: F.R. Hartley (Ed.), The Chemistry of
Organophosphorus Compounds, vol. 3, Wiley-Interscience, Chichester, 1994,
pp. 185–277.
[5] A.C. Hengge, Acc. Chem. Res. 35 (2002) 105–112.
[6] S.D. Lahiri, G. Zhang, D. Dunaway-Mariano, K.N. Allen, Science 299 (2003)
2067–2071.
[7] R.R. Holmes, Acc. Chem. Res. 37 (2004) 746–753.
[8] F.H. Westheimer, Acc. Chem. Res. 1 (1968) 70–78.
0.679 mmol) was added to a solution of 1 (88.5 mg, 0.109 mmol) in
Et2O (3 mL) at ꢁ78 °C. The mixture was then stirred for 1 h at room
temperature. I2 (110 mg, 0.433 mmol) was added to the mixture at
ꢁ78 °C and stirred for 1 h at 0 °C. The reaction was quenched with
aqueous Na2S2O3 (50 mL ꢂ 2). The mixture was extracted with
Et2O (60 mL ꢂ 2), and the organic layer was washed with brine
(50 mL ꢂ 2) and dried over anhydrous MgSO4. After removing the
solvents by evaporation, the resulting crude was separated by TLC
(n-hexane/CH2Cl2 = 4:1) to afford 6b (67.4 mg, 0.0667 mmol, 61%)
as a white solid. Colorless crystals of 6b suitable for X-ray analysis
were obtained by recrystallization from n-hexane/CH2Cl2. M.p.:
[9] G.R.J. Thatcher, R. Kluger, Adv. Phys. Org. Chem. 25 (1989) 99–265.
[10] R.S. Berry, J. Chem. Phys. 32 (1960) 933–938.
[11] K. Mislow, Acc. Chem. Res. 3 (1970) 321–331.
3
160.5–161.0 °C; 1H NMR (CDCl3) d 8.27 (d, 2H, JH–H = 8 Hz), 7.81
(br d, 2H, 3JH–H = 8 Hz), 7.74 (t, 2H, 3JH–H = 8 Hz), 7.64 (t, 2H, 3JH–H
=
[12] E.L. Muetterties, Acc. Chem. Res. 3 (1970) 266–273.
[13] J. Moc, K. Morokuma, J. Am. Chem. Soc. 117 (1995) 11790–11797.
[14] I. Ugi, D. Marquarding, H. Klusacek, P. Gillespie, F. Ramirez, Acc. Chem. Res. 4
(1971) 288–296.
[15] P. Gillespie, P. Hoffman, H. Klusacek, D. Marquarding, S. Pfohl, F. Ramirez, E.A.
Tsolis, I. Ugi, Angew. Chem., Int. Ed. 10 (1971) 687–715.
[16] J.A. Altmann, K. Yates, I.G. Csizmadia, J. Am. Chem. Soc. 98 (1976) 1450–1454.
[17] A. Strich, A. Veillard, J. Am. Chem. Soc. 95 (1973) 5574–5581.
[18] S.-K. Shih, S.D. Peyerimhoff, J. Chem. Soc., Faraday Trans. II 75 (1979) 379–389.
[19] M. Nakamoto, S. Kojima, S. Matsukawa, Y. Yamamoto, K.-Y. Akiba, J.
Organomet. Chem. 643–644 (2002) 441–452.
3
8 Hz), 6.99 (s, 2H), 3.39 (sept, 2H, JH–H = 6.6 Hz), 2.83 (sept, 1H,
3
3
3JH–H = 6.6 H z), 1.34 (d, 6H, JH–H = 6.6 Hz), 1.21 (d, 6H, JH–H
=
6.6 Hz), 0.66 (d, 6H, JH–H = 6.6 Hz); 19F NMR (CDCl3) d ꢁ78.3 (s,
3
6F), ꢁ78.5 (dd, 6F, 3JF–F = 18.5 Hz, 5JF–F = 4.9 Hz), ꢁ114.1 (d, 2F, 2JF–F
=
2
3
286 Hz), ꢁ116.0 (dq, 2F, JF–F = 286 Hz, JF–F = 18.5 Hz), ꢁ117.9 (d,
2
2
5
2F, JF–F = 286 Hz), ꢁ119.3 (dq, 2F, JF–F = 286 Hz, JF–F = 4.9 Hz).
Anal. Calc. for C37H31F20O2Sb: C, 44.03; H, 3.10. Found: C, 44.02; H,
2.83%.
[20] S. Matsukawa, K. Kajiyama, S. Kojima, S.-Y. Furuta, Y. Yamamoto, K.-Y. Akiba,
Angew. Chem., Int. Ed. 41 (2002) 4718–4722.
4.8. Single crystal X-ray analysis of 2a, 4, 6a, and 6b
[21] S. Trippett, Phosphorus Sulfur 1 (1976) 89–98.
[22] S. Trippett, Pure Appl. Chem. 40 (1974) 595–604.
[23] G. Buono, J.R. Llinas, J. Am. Chem. Soc. 103 (1981) 4532–4540.
[24] M. Eisenhut, H.L. Mitchell, D.D. Traficante, R.J. Kaufman, J.M. Deutsch, G.M.
Whitesides, J. Am. Chem. Soc. 96 (1974) 5385–5397.
[25] L.V. Griend, R.G. Cavell, Inorg. Chem. 22 (1983) 1817–1820.
[26] S. Kumaraswamy, C. Muthiah, K.C. Kumara Swamy, J. Am. Chem. Soc. 122
(2000) 964–965.
[27] P. Kommana, S. Kumaraswamy, J.J. Vittal, K.C. Kumara Swamy, Inorg. Chem. 41
(2002) 2356–2363.
[28] P. Kommana, N.S. Kumar, J.J. Vittal, E.G. Jayasree, E.D. Jemmis, K.C. Kumara
Swamy, Org. Lett. 6 (2004) 145–148.
[29] R. Hoffmann, J.M. Howell, E.L. Muetterties, J. Am. Chem. Soc. 94 (1972) 3047–
3058.
[30] R.S. McDowell, A. Streitwieser Jr., J. Am. Chem. Soc. 107 (1985) 5849–5855.
[31] J.A. Deiters, R.R. Holmes, J.M. Holmes, J. Am. Chem. Soc. 110 (1988) 7672–7681.
[32] P. Wang, Y. Zhang, R. Glaser, A.E. Reed, P.V.R. Schleyer, A. Streitwieser Jr., J. Am.
Chem. Soc. 113 (1991) 55–64.
[33] H. Wasada, K. Hirao, J. Am. Chem. Soc. 114 (1992) 16–27.
[34] G.R.J. Thatcher, A.S. Campbell, J. Org. Chem. 58 (1993) 2272–2281.
[35] P. Wang, Y. Zhang, R. Glaser, A. Streitwieser, P.V.R. Schleyer, J. Comput. Chem.
14 (1993) 522–529.
[36] B.D. Wladkowski, M. Krauss, W.J. Stevens, J. Phys. Chem. 99 (1995) 4490–4500.
[37] J.C. Martin, Science 221 (1983) 509–514.
Crystals suitable for the X-ray structural determination were
mounted on a Mac Science DIP2030 imaging plate diffractometer
and irradiated with graphite monochromated Mo K
a radiation
(k = 0.71073 Å) for the data collection. The unit cell parameters
were determined by separately autoindexing several images in
each data set using the DENZO program (MAC Science) [47]. For each
data set, the rotation images were collected in 3° increments with a
total rotation of 180° about the u axis. The data were processed
using SCALEPACK. The structure was solved by a direct method with
the SHELX-97 program [48]. Refinement on F2 was carried out using
the full-matrix leat-squares by the SHELX-97 program [48]. All non-
hydrogen atoms were refined using the anisotropic thermal
parameters. The hydrogen atoms were included in the refinement
along with the isotropic thermal parameters. The crystallographic
data are summarized in Table 3.
Supplementary material
[38] X.-D. Jiang, K.-I. Kakuda, S. Matsukawa, H. Yamamichi, S. Kojima, Y. Yamamoto,
Chem. Asian J. 2 (2007) 314–323.
[39] S. Kojima, K. Kajiyama, M. Nakamoto, K.-Y. Akiba, J. Am. Chem. Soc. 118 (1996)
12866–12867.
[40] K. Kajiyama, M. Yoshimune, M. Nakamoto, S. Matsukawa, S. Kojima, K.-Y.
Akiba, Org. Lett. 3 (2001) 1873–1875.
[41] X.-D. Jiang, S. Matsukawa, H. Yamamichi, Y. Yamamoto, Heterocycles 73
(2007) 805–824.
CCDC 752614, 752615, 752616, and 752617 contain the supple-
mentary crystallographic data for 2a, 4, 6a, and 6b. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
[42] X.-D. Jiang, S. Matsukawa, Y. Yamamoto, Dalton Trans. 28 (2008) 3678–3687.
[43] X.-D. Jiang, S. Matsukawa, H. Yamamichi, Y. Yamamoto, Inorg. Chem. 46 (2007)
5480–5482.
Acknowledgements
[44] V.G.S. Box, J. Mol. Struct. 569 (2001) 167–178.
[45] X.-D. Jiang, S. Matsukawa, H. Yamamichi, K.-I. Kakuda, S. Kojima, Y. Yamamoto,
Eur. J. Org. Chem. (2008) 1392–1405.
[46] When TTP (2,4,6-tri-tert-butylphenyl) was employed, the anti-apicophilic
stiborane and its corresponding apicophilic stiborane were not obtained. It
was due to steric hindrance of the bulky monodentate ligand of TTP.
[47] Z. Otwinowski, W. Minor, Methods in enzymology, in: C.W. Carter Jr., R.M.
Sweet (Eds.), Macromolecular Crystallography, Part A, vol. 276, Academic
Press, 1997, pp. 307–326.
This study was supported by two Grants-in-Aid for Scientific
Research on Priority Areas (Nos. 14340199, 17350021) from the
Ministry of Education, Culture, Sports, Science and Technology,
Japan.
References
[48] G.M. Sheldrick, SHELX-97, University of Göttingen, Göttingen, Germany, 1997.
[1] K.-Y. Akiba, Chemistry of Hypervalent Compounds, Wiley-VCH, New York,
1999.