ˇ
B. Stꢀbr et al.
parent nido tricarbollides [7,8,9-C3B8H11]ꢀ and 7,8,9-
C3B8H12.[4] The 11B NMR spectra of the Cs-symmetry com-
pounds 2ꢀ consist of 1:2:2:2:1 patterns of doublets, whereas
those of the neutral congeners 2 exhibit entirely different
2:2:2:1:1 sets of doublets. The differences being caused by
the presence or absence of the open-face bridging m-10,11
hydrogen.[4] Apart from resonances attributed to the exo-
vacuum sublimation at bath temperatures 100–1508C. Path D: The reac-
tion mixture obtained through path A was, instead of treatment with
aqueous NaOH, treated with CH2Cl2 and concentrated H2SO4 (ꢃ1 mL)
under intensive cooling and shaking at 08C. Further work-up was the
same as that described in path B above. Path C: Deprotonation experi-
ments with PS were identical with those reported earlier.[4] Conventional
deprotonation of compounds 2 with NaH in dry Et2O, followed by filtra-
tion in vacuo, evaporation of the filtrate, and vacuum drying gave a
series of Na+ salts of anions 2ꢀ.
1
skeletal 8-R substituent, the H NMR spectra of compounds
For yields and conditions of individual reactions see Table 1, and NMR
and mass spectra are presented in Table 2.
2ꢀ and 2 consist of one intensity 2 singlet (cage CH). As ex-
emplified by the neutral compounds 2b and 2c, apart from
the low-field resonances due to the aromatic substituents,
their 13C{1H} NMR spectra expectedly exhibit two broad
(13C–11B coupling) 2:1 singlets attributable to the cage C7,9
and C8 carbon vertexes, respectively (a more detailed ac-
count on 13C NMR spectroscopy data of other compounds
will be given in the full paper). Mass spectra of all com-
pounds are entirely in agreement with the calculated m/z
values.
X-ray crystallography: The X-ray data for white crystals of compounds
2bꢀ and 2c were obtained at 150 K by using an Oxford Cryostream low-
temperature device and a Nonius Kappa CCD diffractometer with MoKa
radiation (l=0.71073 ꢃ), a graphite monochromator, and the f and c
scan mode. Data reductions were performed with DENZO-SMN.[7] The
absorption was corrected by integration methods.[8] Structures were
solved by direct methods (Sir92)[7] and refined by full matrix least-
squares based on F2 (SHELXL97).[9] Hydrogen atoms could be mostly lo-
calized on a difference Fourier map. However, to ensure uniformity of
treatment of crystal structures, they were recalculated into idealized posi-
tions (riding model) and assigned temperature factors Uiso(H)=1.2Ueq
The novel SAC method for carbon insertion outlined
above brings new dimensions into the so far restricted area
of tricarbaboranes[5] since it is extremely flexible and allows
for variations in both molecular shape and substituent
design. These synthetic tools may be exploited in cluster en-
gineering and B-cage-based biochemistry, for example, by
varying substituents on carbon and boron positions in 1 and
R in the RCOCl reagent. Other molecular shapes are ex-
pected from thermal rearrangement and metal complexation
reactions involving the tricarbollide part of the molecule.
Moreover, experiments involving bifunctional acyl chlorides
and optimization of individual procedures are in progress
along with extensive structural investigations. It is also rea-
sonable to expect that the SAC strategy can be applied to
cages other than dicarbaborane as well, which may result in
substantial extensions and simplifications in the fields of
general carborane and heteroborane chemistry.
ꢀ
(pivot atom) or of 1.5Ueq for the methyl moieties with C H=0.96, 0.97,
and 0.93 ꢃ for the methyl and aromatic hydrogen atoms, respectively,
ꢀ
ꢀ
and 1.1 ꢃ for B H and C H bonds in the carborane cage. Crystallo-
graphic data for 2c: C13H18B8; Mr =260.75; orthorhombic; P212121; color-
less block; a=7.1240(3), b=9.7851(4), c=21.0540(10) ꢃ; V=
1467.64(11) ꢃ3; Z=4; T=150(1) K; 13462 total reflections; 2397 inde-
pendent reflections; Rint =0.0823; R1 =0.0659 (obs. data); wR2 =0.1254
(all data); GOF=1.072. Crystallographic data for 2cꢀ: C27H36B8N2; Mr =
475.06; triclinic; P-1; light brown block; a=9.7450(4), b=10.2531(5), c=
13.4570(6) ꢃ,
a=90.114(5),
b=98.799(4),
g=93.459(4)8;
V=
1326.24(10) ꢃ3; Z=2; T=150(1) K; 24727 total reflections; 4146 inde-
pendent reflections; Rint =0.0536; R1 =0.0680 (obs. data); wR2 =0.1423
(all data); GOF=1.081.
CCDC-828706 (2c) and CCDC-828705 (2cꢀ) contains the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
Acknowledgements
The work was supported by the Grant Agency of the Czech Republic
(No. P207/11/0705) and the Ministry of Education and Sports of the
Czech Republic (Nos. LC 523 and VZ 0021627501). We also thank Ing.
Experimental Section
Synthesis of the anions [8-R-7,8,9-C3B8H10]ꢀ (2ꢀ) (Et4N+ salts; 2aꢀ: R=
Me; 2bꢀ: R=Ph; 2cꢀ: R=Naph), path A: A solution containing carbor-
ane 1 (125 mg, 1 mmol), Et3N (213 mg, 2.1 mmol), CH2Cl2 (15 mL), and
NaH (48 mg, 2 mmol) was cooled to ꢃꢀ408C, and the corresponding
RCOCl (2.1 mmol) was added in small portions with stirring over 0.5 h.
The cooling bath was then removed, and the stirring was continued at
RT (for reaction times see Table 1). The solvent was then evaporated,
the residue was treated with 5% aqueous NaOH (10 mL) with occasional
shaking, and the resulting mixture was then filtered. The filtrate precipi-
tated upon addition of aqueous Et4NCl (1m, 1 mL), and the white prod-
uct was isolated by filtration and dried under vacuum at RT. Individual
Et4N+ salts can be crystallized from saturated CH2Cl2 solutions by care-
ful addition of a hexane layer onto the surface.
ˇ
Z. Hꢁjkovꢁ and Mgr. V. Sꢀcha for MS measurements.
Keywords: acyl chlorides · boranes · carboranes · cross-
coupling · synthetic methods
[1] B. Brellochs in Contemporary Boron Chemistry (Eds.: M. G. David-
son, A. K. Hughes, K. Wade), Royal Society of Chemistry, Cam-
ˇ
ˇ
´
bridge, 2000, pp. 212–214; B. Brellochs, J. Backovsky, B. Stꢀbr, T. Jelꢀ-
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nek, J. Holub, M. Bakardjiev, D. Hnyk, M. Hofmann, I. Cꢀsarovꢁ, B.
Wrackmeyer, Eur. J. Inorg. Chem. 2004, 3605–3611; for reviews see:
T. Jelꢀnek, M. Thornton-Pett, J. D. Kennedy, Collect. Czech. Chem.
Synthesis of neutral 8-R-7,8,9-C3B8H11 (2) compounds (2a: R=Me; 2b:
R=Ph; 2c: R=Naph), path B: The corresponding Et4N+ salts of anions
2ꢀ (reaction scale ca. 0.5 mmol) were carefully treated with CH2Cl2 and
concentrated H2SO4 (ꢃ1 mL) under intensive cooling and shaking at
08C. The CH2Cl2-soluble components were then separated under N2 at-
mosphere on a silica-gel column with 20% CH2Cl2 in hexane as the
mobile phase to collect fractions of Rf ꢃ0.5. These were evaporated to
give white crystals of compounds 2, which can be further purified by
ˇ
Commun. 2002, 67, 1035–1050; B. Stꢀbr, Pure Appl. Chem. 2003, 75,
1295–1304, and references therein.
[2] X. L. R. Fontaine, N. N. Greenwood, J. D. Kennedy, P. I. Mackinnon,
13158
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 13156 – 13159
Stibr, Bohumil
