Synthesis and characterization of germanium (IV) and silicon (IV) complexes derived from 9-hydroxyphenalenone: X-ray crystal and molecular structure of tris-(9-oxophenalenone)-germanium (IV) and silicon (IV) salts

Article abstract of DOI:10.1016/j.poly.2005.03.097

The germanium (IV) and silicon (IV) complexes, tris-(9-oxophenalenone)- germanium (IV) tetrakis[3,5-bis(trifluoromethyl) phenyl] borate (7 ⁺TFPB^-) and tris-(9-oxophenalenone)-silicon (IV) tetrakis[3,5-bis(trifluoromethyl) phenyl] borate (8⁺TFPB ^-), derived from 9-hydroxyphenalenone have been synthesized and characterized by elemental analyses, infrared spectra and as well as by single crystal X-ray study. The crystal structure of 7⁺TFPB^- and 8⁺TFPB^- shows a one-dimensional chain like structure and π-overlap between the neighbouring phenalenyl planes. The cyclic voltammograms of 7⁺TFPB^- and 8⁺TFPB^- show three reversible one-electron reduction steps due to the formation of the radical, anion and dianion as each phenalenyl moiety accepts an electron.

Full text of DOI:10.1016/j.poly.2005.03.097

Polyhedron 24 (2005) 2076–2083
www.elsevier.com/locate/poly
Synthesis and characterization of germanium (IV) and
silicon (IV) complexes derived from 9-hydroxyphenalenone:
X-ray crystal and molecular structure of
tris-(9-oxophenalenone)-germanium (IV) and silicon (IV) salts
a
S.K. Pal , F.S. Tham , R.W. Reed , R.T. Oakley , R.C. Haddon
a
b
b
a,
*
a
Departments of Chemistry and Chemical and Environmental Engineering, University of California, 900 University Avenue,
Riverside, CA 92521-0403, USA
b
Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L3G1
Received 19 October 2004; accepted 1 December 2004
Available online 13 June 2005
Abstract
The germanium (IV) and silicon (IV) complexes, tris-(9-oxophenalenone)-germanium (IV) tetrakis[3,5-bis(trifluoromethyl) phe-
nyl] borate (7+TFPBꢀ) and tris-(9-oxophenalenone)-silicon (IV) tetrakis[3,5-bis(trifluoromethyl) phenyl] borate (8+TFPBꢀ), derived
from 9-hydroxyphenalenone have been synthesized and characterized by elemental analyses, infrared spectra and as well as by single
crystal X-ray study. The crystal structure of 7+TFPBꢀ and 8+TFPBꢀ shows a one-dimensional chain like structure and p-overlap
between the neighbouring phenalenyl planes. The cyclic voltammograms of 7+TFPBꢀ and 8+TFPBꢀ show three reversible one-
electron reduction steps due to the formation of the radical, anion and dianion as each phenalenyl moiety accepts an electron.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Phenalenone; Cyclic voltammetry; Germanium (IV) complex; Silicon (IV) complex; Neutral radical; X-ray crystal and molecular stru-
cture
1. Introduction
ent physical properties. For example, hexyl radical 5 ex-
ists as monomers in the solid state with the highest
conductivity at room temperature (rRT = 0.05 S/cm) of
any neutral organic compound reported. Radicals 1
and 3 involve face-to-face p–p interactions, with mean
Neutral radicals, and the phenalenyl system in partic-
ular, have been proposed for the preparation of intrinsic
molecular conductors [1]. Sulfur–nitrogen radicals were
the first class of neutral radicals to show conductivity
based on this principle [2]. We have recently reported
the first phenalenyl-based neutral radical conductor [3]
and more recently, the first one-dimensional phenale-
nyl-based neutral radical molecular conductor [4].
Although these compounds differ only in the alkyl
groups (R, for 6 Benzyl), they show significantly differ-
˚
plane separations around 3.33 A at high temperature
˚
and about 3.16 A at low temperature and this change
is accompanied by a magnetic phase transition from
the paramagnetic p-dimer form to the diamagnetic p-di-
mer form, while their conductivities increase by about
two orders of magnitude when the diamagnetic state is
formed [5]. Radical 6 forms a one-dimensional p-step
structure along the y-direction. Nevertheless, its conduc-
tivity (rRT = 1.4 · 10ꢀ3 S/cm) is comparable with that of
the previously reported radicals (1, 3, 5) and greater
*
Corresponding author. Tel.: +1 951 827 2044; fax: +1 951 827 2233.
E-mail address: haddon@ucr.edu (R.C. Haddon).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.03.097

S.K. Pal et al. / Polyhedron 24 (2005) 2076–2083
2077
30
E11/2 = -0.56 V
E21/2 = -0.78 V
(a)
20
10
0
E31/2 = -1.06 V
O
N
N
_
R
1. R = Ethyl
2. R = Propyl
3. R = Butyl
4. R = Pentyl
5. R = Hexyl
6. R = Benzyl
-10
-20
-30
-40
B
+
R
O
u
-50
10
E11/2 = -0.57 V
E21/2 = -0.81 V
(b)
Scheme 1.
5
0
E31/2 = -1.13 V
than that of the propyl (2) and pentyl (4) radicals [6,7]
(see Scheme 1).
-5
In the present paper, we report the synthesis, redox
properties and solid state structures of hexacoordinated
germanium (7+TFPBꢀ) and silicon (8+TFPBꢀ) cations
containing three phenalenyl (PLY) units; such octahe-
dral silicon and germanium complexes with 9-oxophe-
nalenone ligands are not well known.
-10
-15
-20
-25
-1.4
-1.2
-1.0
-0.8
-0.6
-0.4
-0.2
Potential vs. SCE (V)
2. Results and discussion
Fig. 1. Cyclic voltammetry of: (a) 7+TFPBꢀ and (b) 8+TFPBꢀ in
acetonitrile, reference to SCE via internal ferrocene (not shown).
2.1. Synthesis
ride salts which were used as such for the next reaction
without further purification. The chloride salts are quite
insoluble in most common organic solvent but are spar-
ingly soluble in dichloromethane. The anion exchange
reactions were performed in dry dichloromethane at
The synthetic procedure for the preparation of
7+TFPBꢀ and 8+TFPBꢀ are shown in Scheme 2. A tol-
uene solution of 9-hydroxyphenalenone was treated
with GeCl4 and SiCl4 to obtain the corresponding chlo-
+
-
Cl
+
+
O
O
2-
Toluene
Reflux
O
M
+
O
3
MCl4
+
O
O
O
OH
M = Ge (7+Cl-), Si (8+Cl-)
+
+
+
F3C
CF3
O
O
F3C
CF3
NaTFPB
CH2Cl2
O
M
2-
O
-
B
O
O
F3C
CF3
F3C
CF3
+
M = Ge (7+TFPB-), Si (8+TFPB-)
Scheme 2.

2078
S.K. Pal et al. / Polyhedron 24 (2005) 2076–2083
room temperature. Addition of solid sodium tetra-
kis[3,5-bis(trifluoromethyl)phenyl]borate (NaTFPB)
+
leads to dissolution of the cations due to the formation
of the TFPB salt. The excess chloride salt and the NaCl
formed during the reaction were separated by filtration.
Compound 7+TFPBꢀ and 8+TFPBꢀ were found to be
stable in the solid state and in solution at room
temperature.
+e
-e
1/2
E
1
= -0.29V
OEt
OEt
OEt
OEt
+
-
10 BF
4
2.2. Electrochemistry
Scheme 5.
The cyclic voltammetry of 7+TFPBꢀ and 8+TFPBꢀ
exhibit three reversible redox waves at E11=2 ¼ ꢀ0.56 V,
plexes follows the electronegativities of the central
atoms: Ge, 2.02; Si, 1.74. The potentials may be com-
pared to the reduction potentials observed for 9+:
E11=2 ¼ ꢀ0.34 V and E12=2 ¼ ꢀ0.62 V (Scheme 4), and
10+: E11=2 ¼ ꢀ0.29 V versus SCE (Scheme 5). The ease
of the first reduction of these compounds follows the or-
der: 10+ > 9+ > 7+ and 8+, which is in the sequence of 1,
E12=2 ¼ ꢀ0.78 V, E31=2 ¼ ꢀ1.06 V and E11=2 ¼ ꢀ0.57 V,
E12=2 ¼ ꢀ0.81 V and E13=2 ¼ ꢀ1.13 V versus SCE
(Fig. 1) corresponding to the successive reduction to
radical, anion and dianion of the phenalenyl moiety
(Scheme 3). The relative ease of reduction of these com-
+
-
TFPB
+
+
+
O
O
O
O
O
M
+
O
O
M
+
O
+e
-e
2-
2-
O
O
O
O
E11/2 = -0.56 V (M = Ge)
-0.57 V (M = Si)
7+/8+
7/8
O
O
O
O
O
M
+
O
2-
O
M
O
+e
-e
+e
-e
2-
O
O
O
O
E21/2 = -0.78 V (M = Ge)
-0.81 V (M = Si)
E31/2 = -1.06 V (M = Ge)
-1.13 V (M = Si)
7-/8-
72-/82-
Scheme 3.
+
-
TFPB
+
B
+
O
O
O
O
O
O
O
O
+e
-e
+e
-e
_
_
_
B
B
O
O
O
O
E21/2 = -0.62 V
E11/2 = -0.34 V
+
9-
9+
9
Scheme 4.

S.K. Pal et al. / Polyhedron 24 (2005) 2076–2083
2079
Table 1
Half-wave potentialsa and the disproportionation potentials of various
tetraphenylborate and TFPB salts
2 and 3 phenalenyl units per molecule. This sequence
may be understood by considering the degree of charge
that is localized in a single phenalenyl ring in the com-
plexes – clearly one PLY ring bears most of the charge
density in the salt 10+, and along this series it is apparent
that any given PLY unit will bear a lower positive
charge in the salt as the number of the PLY units in-
creases and, therefore, the first electron transfer will be-
come progressively more difficult. This is in agreement
with the bond length data for the salts 7+, 8+ and the
beryllium compound, [8] shown in Table 3 where it
may be seen that the C1–O1 and C9–O2 bond lengths
Cation
E11=2
E12=2
E13=2
DE2–1
References
7+TFPBꢀ
ꢀ0.56
ꢀ0.57
ꢀ0.75
ꢀ0.75
ꢀ0.73
ꢀ0.74
ꢀ0.74
ꢀ0.68
ꢀ0.78
ꢀ0.81
ꢀ1.10
ꢀ1.10
ꢀ1.09
ꢀ1.11
ꢀ1.11
ꢀ1.02
ꢀ1.06
ꢀ1.13
ꢀ0.22
ꢀ0.24
ꢀ0.35
ꢀ0.35
ꢀ0.36
ꢀ0.37
ꢀ0.37
ꢀ0.34
this work
this work
8+TFPBꢀ
1+
2+
3+
4+
5+
6+
a
[5]
[6]
[5]
[7]
[3]
[4]
In acetonitrile, referenced to SCE (saturated calomel electrode) via
internal reference ferrocene.
˚
are 1.302, 1.296, 1.287 and 1.300, 1.308, 1.290 A, respec-
tively. The bond length should be a sensitive indicator of
the degree of charge separation in the complexes with
longer bond lengths associated with a greater degree of
charge separation. A six-coordinated silicon (IV) com-
plex with a tripodal phenalenyl-based hexadentate li-
gand was recently shown to undergo three reductions
at potentials of ꢀ0.97, ꢀ1.19 and ꢀ1.43 V versus SCE
[9], due to reduction to the radical, anion and dianion.
This compound is more difficult to reduce than
7+TFPBꢀ and 8+TFPBꢀ, because of the presence of
nitrogen in the coordination sphere of silicon.
state and is well established as an important discrimina-
tor for organic metals [10,11]. The three reduction waves
in the cyclic voltammogram indicate that it is possible to
introduce one electron into each of the PLY ring
(Scheme 3).
2.3. Crystallography
Single crystals of 7+TFPBꢀ and 8+TFPBꢀ were grown
from diethyl ether and hexane solution at room tempera-
ture and studied by single crystal X-ray diffraction. Crys-
tallization of 7+TFPBꢀ and 8+TFPBꢀ gave needle like
crystals of diethyl ether solvates, which belong to the tri-
The disproportionation potential of 7+ and 8+,
DE2–1 ¼ E1=2 ꢀ E11=2 ¼ ꢀ0.22 and ꢀ 0.24 V versus SCE,
2
are considerably lower in magnitude than the values
found for the boron compounds previously reported
[3–5]. Table 1 lists the results of the cyclic voltammetry
experiments carried out on salts 1+, 2+, 3+, 4+, 5+, 6+
ꢀ
clinic space group P1, with two molecules per unit cell.
Table 2 provides crystal data of compound 7+TFPBꢀ
and 8+TFPBꢀ. An ORTEP plot of the molecular struc-
ture of 7+TFPBꢀ and 8+TFPBꢀ are shown in Fig. 2.
The molecular geometry around germanium and sili-
con are approximately octahedral, consisting of three
bidentate chelating PLY ligands. The plane of the three
PLY rings in 7+TFPBꢀ reveal some distortion from the
ideal octahedral symmetry; their dihedral angles are 84ꢁ
ꢀ
(with BPh4 as the counterion) together with the new
compounds. The small DE2–1 value seen in 7+ and 8+
can be explained in terms of the reduction in the electron
repulsion by the delocalization of the charge over the
three PLY sites. The DE2–1 value largely determines
the on-site Coulomb correlation energy (U) in the solid
Table 2
Crystal data for 7+TFPBꢀ and 8+TFPBꢀ
Compound
7+TFPBꢀ
8+TFPBꢀ
Formula
C71H33BF24GeO6 Æ[C4H10O]2.5
triclinic
1706.67
C71H33BF24SiO6[C4H10O]2.5
triclinic
1662.17
Crystal system
Formula weight
Unit cell dimensions
˚
a (A)
12.2965(16)
17.104(2)
18.536(2)
75.645(3)
82.109(3)
74.879(2)
3635.0(8)
12.297(2)
17.124(3)
17.124(3)
75.762(3)
82.337(4)
74.869(3)
3636.0(11)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
˚
V (A)
ꢀ
ꢀ
Space group
Z
P1
P1
2
223(2)
0.543
2
233(2)
0.154
Temperature (K)
l (mmꢀ1
)
Data/restrain/parameter
Final R indices [I > 2r(I)]
R indices (all data)
14 870/1082/1227
R1 = 0.0543, wR2 = 0.1489
R1 = 0.0758, wR2 = 0.1676
14 864/631/1323
R1 = 0.0589, wR2 = 0.1557
R1 = 0.0949, wR2 = 0.1873

2080
S.K. Pal et al. / Polyhedron 24 (2005) 2076–2083
Fig. 2. ORTEP diagram of the molecular structure of: (a) 7+TFPBꢀ and (b) 8+TFPBꢀ.
Fig. 3. ORTEP diagram of the molecular structure of: (a) 7+TFPBꢀ and (b) 8+TFPBꢀ (only the cation part) and the numbering of the atoms.
(C1–C9b, C11–C19b), 80.5ꢁ (C11–C19b, C21–C29b) and
102.9ꢁ (C21–C29b, C1–C9b) (see Fig. 3), rather than 90ꢁ
as expected in ideal octahedral symmetry. The corre-
sponding dihedral angles for the silicon compound are
83.8ꢁ, 80.1ꢁ and 102.8ꢁ. The dihedral angles are different
from that observed in the cis-hexacoordinate (tropolo-
nato)2 SiPh2 (an a-diketonate compound) in which the
angle of the two tropolonate chelating planes is 81.1ꢁ
[12]. The structure distorts so that the metal atom devi-
ates from the chelate-ring plane, and this has been noted
in studies of several acetylacetonato complexes and is
ascribed to the packing forces in the crystals [13]. The
comparison of the bond lengths in Table 3 indicates that
there is a considerable amount of charge separation in
the cationic complexes of germanium and silicon as re-
flected by the C–O bond lengths in these compounds.
The structure of the counter anion (TFPB) also devi-
ates from the ideal tetrahedral geometry and this is
probably due to the presence of bulky substituents
(CF3) on the phenyl ring. In the crystal structure of
7+TFPBꢀ four out of eight CF3 groups in the counter
anion show disorder. In compound 8+TFPBꢀ all the
CF3 groups were refined as disordered CF3.
In the molecular structure of the salt (7+TFPBꢀ),
each cation is involved in p–p interactions with two
neighbouring molecules and thus these cations form
chains in the solid state (Fig. 4). The chain formation
Table 3
Comparison of bond length (in A) among Be, Ge and Si complexes
˚
Bond type
[PLY(O,O)]2Be
7+TFPBꢀ
8+TFPBꢀ
O1–C1
O2–C9
1.287(2)
1.290(2)
1.427(3)
1.421(2)
1.345(3)
1.422(3)
1.422(2)
1.397(2)
1.375(3)
1.384(3)
1.400(2)
1.408(2)
1.423(2)
1.349(2)
1.430(2)
1.426(2)
1.424(2)
1.302(4)
1.300(4)
1.419(4)
1.412(4)
1.349(5)
1.424(5)
1.408(4)
1.402(5)
1.383(6)
1.370(6)
1.404(5)
1.414(4)
1.415(5)
1.356(5)
1.423(4)
1.418(4)
1.430(4)
1.296(4)
1.308(4)
1.428(4)
1.417(4)
1.351(5)
1.430(5)
1.421(4)
1.396(5)
1.372(6)
1.380(6)
1.406(5)
1.421(4)
1.421(5)
1.351(5)
1.426(4)
1.414(4)
1.418(4)
C1–C2
C1–C9a
C2–C3
C3–C3a
C3a–C9b
C3a–C4
C4–C5
C5–C6
C6–C6a
C6a–C9b
C6a–C7
C7–C8
C8–C9
C9–C9a
C9a–C9b

S.K. Pal et al. / Polyhedron 24 (2005) 2076–2083
2081
Fig. 4. Packing diagram of the cations (7+) in the lattice, showing the
overlap between four of the neighbouring cations: (a) and (b) are
perpendicular views of each of the two sets of phenalenyl units.
Fig. 6. The closest distances between a pair of cations 7+.
methane was distilled from anhydrous CaH2 before
use. Germanium tetrachloride and silicon tetrachloride
(Aldrich) were all commercial products and were used
as received. 9-Hydroxyphenalenone and sodium tetra-
kis[3,5-bis(trifluoromethyl)phenyl]borate
(NaTFPB)
were synthesized according to literature procedures
[14,15]. Melting points are uncorrected. Infrared spectra
were recorded on a Nicolet Nexus 670 FT-IR spectrom-
1
eter (at 2 cmꢀ1 resolution). H NMR spectra were run
Fig. 5. Overlap between a pair of cations 7+.
on a Varian Inova 300 MHz NMR spectrometer.
Elemental analysis were performed by Microanalysis
Laboratory (School of Chemical Science, University of
Illinois, Urbana, IL).
occurs along the Z-direction of the unit cell. Out of the
three two PLY are involved in p-dimer chain formation.
But the C–C distances of the PLY carbon with the near-
est neighbour are not identical. There are two sets of C–C
distances are shown in the Fig. 6. The shortest C–C dis-
3.2. Preparation of 7+Clꢀ
+
ꢀ
˚
tance observed is 3.274 A for compound 7 TFPB and
9-Hydroxyphenalenone (1.96 g, 10 mmol) in anhy-
drous toluene (50 mL) was treated with germanium tetra-
chloride (0.71 g, 3.3 mmol) under argon and the mixture
was refluxed for 12 h. The yellow solid was isolated by
filtration (1.5 g, 32%). Melting point: Compound does
not melt till 380 ꢁC. 1H NMR (CD3OD); d 8.28 (d,
6H), 8.18 (d, 6H), 7.69 (t, 3H), 7.18 (d, 6H). IR (ATR,
4000–600 cmꢀ1): 3002 (w), 2986 (w), 1622 (m), 1570 (s),
1496 (s), 1467 (w), 1429 (w), 1353 (w), 1335 (w), 1322
(w), 1273 (s), 1238 (m), 1181 (w), 1142 (w), 1129 (w),
982 (w), 851 (s), 763 (s), 750 (s), 701 (w), 682 (w).
+
ꢀ
˚
3.297 A for compound 8 TFPB . The projection of cat-
ion 7+ (Fig. 5) demonstrates the almost perfect superpo-
sition of some of the carbon atoms in the p-dimers. A
similar packing pattern was observed for cation 8+
which are not shown in the figure.
3. Experimental
3.1. Materials and methods
All manipulations were carried out under an
atmosphere of argon using standard Schlenk techniques.
Solvents were dried and distilled according to the
standard procedures. Toluene was distilled from sodium
benzophenone ketyl immediately before use. Dichloro-
3.3. Preparation of 7+TFPBꢀ
A mixture of 7+Clꢀ (1.02 g, 1.47 mmol) and NaTFPB
(1.15 g, 1.30 mmol) was added to 100 mL of dry

2082
S.K. Pal et al. / Polyhedron 24 (2005) 2076–2083
CH2Cl2. The mixture was stirred for 3 h until all yellow
solids went into the solution and a white solid had pre-
cipitated. The yellow solution was filtered and the sol-
vent was evaporated to give a brownish-yellow solid.
Crystallization from ether–hexane (10:1) gave yellow
needles. Yield: 1.85 g (93%); m.p. 98 ꢁC. 1H NMR
(CDCl3): d 8.36 (d, 6H), 8.28 (d, 6H), 7.79 (t, 3H),
7.72 (br, 8H), 7.48 (br, 4H), 7.28 (d, 6H). IR (ATR,
4000–600 cmꢀ1): 3050 (w), 3028 (w), 1627 (w), 1618
(w), 1568 (m), 1496 (m), 1470 (w), 1434 (w), 1354 (w),
1336 (w), 1273 (s), 1241 (m), 1122 (s), 987 (w), 854
(w), 759 (w), 712 (w). Anal. Calc. for C71H33BO6GeF24:
C, 56.05; H, 2.19; B, 0.71; Ge, 4.77. Found: C, 57.80; H,
2.71; B, 0.69; Ge, 4.39%.
R1 = 0.0758 and wR2 = 0.1676 (Table 2). The structure
of 8+TFPBꢀ was refined with 14864 reflections, yielding
R[I > 2r(I)], R1 = 0.0589, wR2 = 0.1557, and R indices
for all data R1 = 0.0949, and wR2 = 0.1873 (Table 2).
Full details, including bond lengths and bond angles,
are given in the supporting Information.
3.7. Cyclic voltammetry
Cyclic Voltammetry was performed using a PINE
Bipotentiostat, model AFCC1BP1, with scan rates 50–
100 mV sꢀ1 on solutions (<10ꢀ3 M) of 7+TFPBꢀ and
8+TFPBꢀ in CH3CN (dried by distillation from P2O5
and CaH2) containing 0.1 M tetra-n-butylammonium
hexafluorophosphate as supporting electrolyte. Poten-
tials were scanned with respect to the quasi-reference elec-
trode in a single compartment cell fitted with Pt electrodes
and referenced to the Fc/Fc+ couple of ferrocene at 0.38 V
versus SCE [16]. The Epa ꢀ Epc separation of the revers-
ible couples was within 10% of that of the Fc/Fc+ couple.
3.4. Preparation of 8+Clꢀ
9-Hydroxyphenalenone (2.4 g, 12.2 mmol) was dis-
solved in 50 mL of dry toluene followed by addition
of SiCl4 (4 mL, 4 mmol) in dichloromethane. The reac-
tion mixture was refluxed for 8 h. The yellow solid was
isolated by filtration (3.0 g, 86%). When a melting point
determination was attempted, the salt turned brown
4. Summary and conclusions
1
(ꢁ290 ꢁC). H NMR (CD3OD): d 8.60 (d, 6H), 8.48
In summary, two new cationic tris-(9-oxophenale-
none) germanium (IV) and silicon (IV) of 7+ and 8+
have been synthesized in high yield and high purity.
Cyclic voltammetry indicated these complexes could be
easily reduced to its corresponding radical. The hexaco-
ordinated geometry was determined by single crystal
X-ray diffraction analysis in the solid state. Molecular
structure also shows a p–p interaction between the two
neighboring PLY plane and a one-dimensional chain
like structure in the solid state.
(d, 6H), 7.91 (t, 3H), 7.26 (d, 6H). IR (ATR, 4000–600
cmꢀ1): 3004 (w), 2987 (w), 1621 (w), 1571 (w), 1501
(w), 1343 (w), 1274 (m), 1256 (m), 1144 (w), 1125 (w),
993 (w), 852 (w), 764 (s), 749 (s), 652 (m), 641 (s).
3.5. Preparation of 8+TFPBꢀ
Synthesis of 8+TFPBꢀ is exactly the same as the prep-
aration of 7+TFPBꢀ. Yield: 1.8 g (88%); m.p. 84 ꢁC. 1H
NMR (CDCl3); d 8.37 (d, 6H), 8.26 (d, 6H), 7.78 (t, 3H),
7.70 (br, 8H), 7.45 (br, 4H), 7.24 (d, 6H). IR (ATR,
4000–600 cmꢀ1): 3004 (w), 2987 (w), 1621 (w), 1576
(m), 1504 (m), 1349 (m), 1275 (s), 1240 (w), 1119 (s),
993 (w), 851 (m), 764 (m), 751 (m). Anal. Calc. for
C71H33BO6SiF24: C, 57.74; H, 2.24. Found: C, 57.95;
H, 2.11%.
5. Supplementary material
Crystallographic data have been deposited at the
Cambridge Crystallographic Data Center, CCDC Refer-
ence Nos. 265567 (7+TFPBꢀ) and 265568 (8+TFPBꢀ).
Copies of this information may be obtained free of charge
from the Director, CCDC, 12 Union Road, Cambridge,
CB2 IEZ, UK (fax: +44 1223 336033; e-mail: deposit@
ccdc.cam.ac.uk or http://www.ccdc. cam.ac.uk).
3.6. X-ray crystallography
Data were collected on a Bruker SMART 1000 plat-
form-CCD X-ray diffractometer system (Mo radiation,
˚
k = 0.71073 A, 50 kV/40 mA power) at 223 K. The or-
ange crystal gave a triclinic unit cell (space group P1,
˚
z = 2), with unit cell parameters a = 12.2965(16) A,
ꢀ
Acknowledgement
˚
˚
This work was supported by the Office of Basic En-
ergy Sciences, Department of Energy, under Grant
Nos. DE-FG03-01ER45879.
b = 17.104(2) A, c = 18.536(2) A, a = 75.645(3)ꢁ,
3
˚
b = 82.109(3)ꢁ, c = 74.879(2)ꢁ and V = 3635.0(8) A for
compound 7+TFPBꢀ and a = 12.297(2) A, b =
˚
˚
˚
17.124(3) A, c = 18.505(3) A, a = 75.762(3)ꢁ, b =
3
˚
82.337(4)ꢁ, c = 74.869(3)ꢁ and V = 3636.0(11) A for
References
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fined with 14870 reflections, yielding R[I > 2r(I)],
R1 = 0.0543, wR2 = 0.1489, and R indices for all data
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