11176 Inorganic Chemistry, Vol. 49, No. 23, 2010
Songkram et al.
hydrophobic parts, based on combinations of one or more
benzyl-o-carborane moieties with a benzene platform, and
along this line, we designed compounds 4, 5, and 6 with larger
π-spaces. Here, we describe the synthesis and structural analysis
of bis- and tris(2-benzyl-o-carboran-1-yl)benzene derivatives
4-6.
was quenched with 3 N HCl aqueous solution, and the whole
was extracted with AcOEt. The organic phase was washed with
water and brine, dried over Na2SO4, and then evaporated. The
residue was purified by column chromatography on silica gel
with n-hexane/AcOEt 10:1 to afford 234 mg (44%) of the title
compound as a colorless solid; colorless needles (CH2Cl2-n-
1
hexane); mp 201.0-202.0 °C; H NMR (400 MHz, CDCl3) δ
(ppm) 1.4-3.4 (brm, 20H), 3.11 (s, 4H), 6.79 (dd, J = 2.0 Hz, 7.7
Hz, 4H), 7.20-7.28 (m, 6H), 7.58 (t, J = 7.7 Hz, 1H), 7.88
(dd, J = 1.9 Hz, 7.7 Hz, 2H), 8.06 (t, J = 1.8 Hz, 1H); 13C NMR
(100 MHz, CDCl3) δ (ppm) 41.2, 82.0, 82.2, 128.1, 128.5, 129.8,
129.9, 132.1, 133.4, 134.6, 134.9; 11B NMR (126.9 MHz, CDCl3)
δ (ppm) -3.3 (4B), -9.8 (16B); MS (EI) m/z 542 (Mþ, 100%);
HRMS calcd for C24H38B20 542.4980; found 542.4980; Anal.
Calcd for C24H38B20 C 53.11, H 7.06; found C 53.08, H 7.08.
1,4-Bis(2-benzyl-1,2-dicarba-closo-dodecaboran-1-yl)benzene (5).
To a suspension of NaH (60%, 88 mg, 2.2 mmol) in 4 mL of dry
DME was added 10 (363 mg, 1.0 mmol) in one portion. After
15 min, benzyl bromide (0.3 mL, 25.2 mmol) was added, and the
mixture was stirred for 24 h at room temperature. The reaction
was quenched with 3 N HCl aqueous solution, and the whole
was extracted with AcOEt. The organic phase was washed with
water and brine, dried over Na2SO4, and then evaporated. The
residue was purified by column chromatography on silica gel
with n-hexane/AcOEt 7:1 to afford 182 mg (34%) of the title
compound as a colorless solid; colorless needles (CH2Cl2-n-
Experimental Section
General Considerations. Melting points were determined with
a Yanagimoto micro-melting point apparatus without correction.
1H NMR, 13C NMR, and 10B NMR spectra were recorded with
JEOL JNM-LA-400 and JNM-FX-400 spectrometers. Chemi-
cal shifts for 1H NMR spectra were referenced to tetramethylsi-
lane (0.0 ppm) as an internal standard. Chemical shifts for 13
C
NMR spectra were referenced to residual 13C present in deuterated
solvents. Chemical shift values for 11B spectra were referenced
relative to external BF3 OEt (0.0 ppm, with negative values
3
upfield). The chemical shifts are reported in ppm (δ scale) and
all coupling constants (J) values are given in hertz (Hz). The
splitting patterns are designed as follows: s (singlet), d (doublet),
t (triplet), q (quartet), m (multiplet), and br (broad). Mass
spectra were recorded on a JEOL JMS-DX-303 spectrometer.
Elemental analyses were performed by a Perkin-Elmer 2400
CHN spectrometer.
Materials. Unless otherwise noted, the reagents and solvents
were purchased from Aldrich Chemical Co., Kanto Chemicals,
Tokyo Kasei, or Wako Chemicals, Inc., and were used as
received. Decaborane(14) was purchased from Katchem sro
(Prague, Czech Republic). Compound 12 was prepared accord-
ing to the literature.19
1
hexane); mp >300 °C; H NMR (400 MHz, CDCl3) δ (ppm)
1.4-3.4 (brm, 20H), 3.13 (s, 4H), 6.81 (dd, J = 1.5 Hz, 7.8 Hz,
4H), 7.19-7.27 (m, 6H), 7.77 (s, 4H); 13C NMR (100 MHz, CDCl3)
δ (ppm) 41.3, 81.4, 82.0, 128.1, 128.5, 129.9, 131.9, 133.6, 134.6;
11B NMR (126.9 MHz, CDCl3) δ (ppm) -3.3 (4B), -9.8 (16B);
MS (EI) m/z 542 (Mþ, 100%); HRMS calcd for C10H26B20
542.4980; Found 542.4973; Anal. calcd for C24H38B20 C 53.11,
H 7.06; found C 53.18, H 7.09.
1,3-Bis(1,2-dicarba-closo-dodecaboran-1-yl)benzene (9). A solu-
tion of decaborane (14) (460 mg, 3.8 mmol), 1,3-diethynylben-
zene 7 (237 mg, 1.9 mmol) and 1 mL of acetonitrile in 10 mL of
dry benzene was refluxed for 48 h under an argon (Ar) atmo-
sphere. After removal of the solvent, the residue was purified by
column chromatography on silica gel with n-hexane/CH2Cl2 4:1
to afford 295 mg (43%) of the title compound as a colorless
solid; colorless needles (CH2Cl2-n-hexane); mp 260-261 °C; 1H
NMR (396 MHz, CDCl3) δ (ppm) 1.5-3.5 (brm, 20H), 3.92
(s, 2H), 7.33 (t, J = 8.2 Hz, 1H), 7.51 (dd, J = 2.0 Hz, 8.2 Hz,
2H), 7.66 (t, J = 2.0 Hz, 1H); 13C NMR (100 MHz, CDCl3) δ
(ppm) 60.1, 75.1, 127.6, 128.9, 129.4, 134.4; 11B NMR (127 MHz,
CDCl3) δ (ppm) -12.7 (4B), -11.6 (4B), -10.9 (4B), -8.8 (4B),
-3.9 (2B), -1.9 (2B); MS (EI) m/z 362 (Mþ, 100%); HRMS
calcd for C10H26B20 362.4041; found 362.4035; Anal. Calcd for
C10H26B20 C 33.13, H 7.23; found C 33.25, H 7.36.
1,3,5-Tris(1,2-dicarba-closo-dodecaboran-1-yl)benzene (13).
A solution of decaborane (14) (7.4 g, 61 mmol), 1,3,5-triethy-
nylbenzene 1218 (3.0 g, 20 mmol, and 8 mL of acetonitrile in
80 mL of dry benzene was refluxed for 72 h under an Ar atmo-
sphere. After removal of the solvent, the residue was purified by
column chromatography on silica gel with n-hexane/AcOEt 4:1
to afford 4.5 g (45%) of the title compound as a colorless solid;
1
colorless needles (CH2Cl2-n-hexane); mp >300 °C; H NMR
(400 MHz, CDCl3) δ (ppm) 1.5-3.5 (brm, 30H), 3.88 (s, 4H),
7.67 (s, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm) 60.2, 74.0,
128.8, 135.3; 11B NMR (127 MHz, CDCl3) δ (ppm) -12.1 (12B),
-10.9 (6B), -8.7 (9B), -1.4 (3B); MS (EI) m/z 504 (Mþ, 100%);
HRMS calcd for C12H36B30 504.5827; found 504.5818; Anal.
calcd for C24H38B20 0.1n-hexane C 29.48, H 7.34; found C
3
1,4-Bis(1,2-dicarba-closo-dodecaboran-1-yl)benzene (10).
A solution of decaborane (14) (4.0 g, 33 mmol), 1,4-diethynyl-
benzene 8 (2.0 g, 16 mmol), and 5 mL of acetonitrile in 50 mL of dry
benzene was refluxed for 72 h under an Ar atmosphere. After
removal of the solvent, the residue was purified by column chroma-
tography on silica gel with n-hexane:AcOEt 10:1 to afford 3.4 g
(59%) of the title compound as a colorless solid; colorless
needles (CH2Cl2-n-hexane); mp >300 °C; 1H NMR (396 MHz,
CDCl3) δ (ppm) 1.5-3.5 (brm, 20H), 3.92 (s, 2H), 7.45 (s, 4H);
13C NMR (100 MHz, CDCl3) δ (ppm) 59.9, 74.8, 128.0, 135.2;
11B NMR (127 MHz, CDCl3) δ (ppm) -12.7 (4B), -11.0 (8B),
-8.8 (4B), -3.8 (2B), -1.9 (2B); MS (EI) m/z 362 (Mþ, 100%);
HRMS calcd for C10H26B20 362.4041; found 362.4039; Anal.
Calcd for C10H26B20: C 33.13, H 7.23; found C 33.25, H 6.98.
1,3-Bis(2-benzyl-1,2-dicarba-closo-dodecaboran-1-yl)benzene (4).
To a suspension of NaH (60%, 88 mg, 2.2 mmol) in 4 mL of dry
DME was added 9 (363 mg, 1.0 mmol) in one portion. After
15 min, benzyl bromide (0.3 mL, 25.2 mmol) was added, and the
mixture was stirred for 24 h at room temperature. The reaction
29.44, H 7.31.
1,3,5-Tris(2-benzyl-1,2-dicarba-closo-dodecaboran-1-yl)benzene
(6). To a suspension of 60% NaH (240 mg, 6 mmol) in 20 mL of
dimethoxyethane (DME) was added 13 (500 mg, 1 mmol), in one
portion. After 15 min, benzyl bromide (1.5 mL, 12.6 mol) was
added. The reaction mixture was stirred for 24 h at room
temperature, quenched with 3 N aqueous HCl solution, and
extracted with AcOEt. The organic phase was washed with water
and brine, dried over Na2SO4, and concentrated. The residue was
purified by column chromatography on silica gel with n-hexane/
AcOEt 8:1 to afford 340 mg (44%) of the title compound as a
white solid; Colorless needles (CH2Cl2-n-hexane); mp 257-
1
258 °C; H NMR (400 MHz, CDCl3) δ (ppm) 1.5-3.3 (brm,
30H), 3.12 (s, 6H), 6.77-6.79 (m,6H), 7.20-7.29 (m, 9H), 8.22
(s, 3H); 13C NMR (100 MHz, CDCl3) δ (ppm) 41.5, 80.5, 82.3,
128.4, 128.8, 129.7, 133.3, 134.1, 136.1; 11B NMR (126.9 MHz,
CDCl3) δ (ppm) -9.54 (8B), -2.85 (2B); MS (EI) m/z 775 (Mþ,
100%); HRMS calcd for C12H36B30 774.7235; found 774.7219;
Anal. calcd for C33H54B30 C 51.14, H 7.02; found C 51.25, H 7.03.
X-ray Crystallography. Details of data collection and struc-
ture refinement are given in Table 1. Diffraction data were
(19) Edwin, W.; Manfred, H.; Erich, K.; Wolfgang, O.; Matyas, C.;
Ingeborg, C. J. Chem. Soc., Perkin Trans. 2 1988, 1251–1257.