Microwave-assisted kumada-type cross-coupling reactions of iodinated carba-closo-dodecaborate anions

Article abstract of DOI:10.1021/ic202638k

The microwave-assisted Pd-catalyzed Kumadatype cross-coupling reaction of iodinated carba-closo-dodecaborate anions requires smaller amounts of Grignard reagent and catalyst and results in higher yields in much shorter reaction times in comparison to a re

Full text of DOI:10.1021/ic202638k

Article
pubs.acs.org/IC
Microwave-Assisted Kumada-Type Cross-Coupling Reactions of
Iodinated Carba-closo-dodecaborate Anions
Alexander Himmelspach,† Guido J. Reiss,‡ and Maik Finze*,†
†Institut fur Anorganische Chemie, Julius-Maximilians-Universitat Wurzburg, Am Hubland, 97074 Wurzburg, Germany
̈
̈
̈
̈
̈
‡Institut fur Anorganische Chemie und Strukturchemie II, Heinrich-Heine-Universitat Dusseldorf, Universitatsstrasse 1,
̈
̈
̈
40225 Dusseldorf, Germany
̈
S
* Supporting Information
ABSTRACT: The microwave-assisted Pd-catalyzed Kumada-
type cross-coupling reaction of iodinated carba-closo-dodeca-
borate anions requires smaller amounts of Grignard reagent
and catalyst and results in higher yields in much shorter re-
action times in comparison to a reaction with conven-
tional heat transfer. 12-Ph3P-closo-1-CB11H11 was identified as
the side product of the cross-coupling reactions that use
[PdCl2(PPh3)2]. The inner salt, which is the first example for a {closo-1-CB11} cluster with a B−P bond, was selectively
synthesized via a related microwave-assisted cross-coupling protocol and characterized by NMR spectroscopy, elemental analysis,
and single-crystal X-ray diffraction. In addition, the crystal structures of the tetraethyl ammonium salts of [12-Ph-closo-
1-CB11H11]−, [12-(4-MeOC6H4)-closo-1-CB11H11]−, and [12-(H2C(Me)CCC)-closo-1-CB11H11]− are described.
irradiation resulted in higher yields and improved reaction
conditions as reported earlier for related transition-metal-
catalyzed cross-coupling reactions of organic substrates24−27
including Kumada-type cross-coupling reactions.28 In the field
of boron cluster chemistry only a few examples of microwave-
assisted reactions have been described so far, e.g., preparation
of methylated carba-closo-dodecaborate anions29,30 and metal-
lacarboranes.31 The inner salt 12-Ph3P-closo-1-CB11H11 (2) was
identified as a side product of the cross-coupling reactions for
the first time. Its selective synthesis is described as well. The
crystal structure of the zwitterion 2 was obtained, and a
comparison of the experimental bond distances to those of
[Ph3P-closo-B12H11]− and to values derived from theoretical
calculations is given. Furthermore, crystal structures of the
[Et4N]+ salts of the anions [12-Ph-closo-1-CB11H11]− (1h), [12-
(4-MeO-C6H4)-closo-1-CB11H11]− (1j), and [12-(H2C(Me)-
CCC)-closo-1-CB11H11]− (1g) are reported.
INTRODUCTION
■
Carba-closo-dodecaborate anions are of growing interest
because they are used in various applications,1 for example,
as weakly coordinating anions,2−6 in catalysis,7−10 in ionic liq-
uids,11,12 and in supramolecular chemistry.13,14 {closo-1-CB11}
clusters with substituents that can be easily modified are
especially useful because they may allow easy incorporation of
boron clusters into more complex structures. A number of
syntheses of derivatives with an easy-to-modify functional
group that is bonded to the cluster carbon atom have been
reported,1 e.g., [1-R-closo-1-CB11H11]− (R = CO2H, NH2,
CN).15,16 In contrast, only a very limited number of regio-
selective syntheses for carba-closo-dodecaborate anions with a
functional group that is bonded to one of the boron atoms has
been described. The Pd-catalyzed cross-coupling reaction of
Grignard reagents with mono- and diiodinated {closo-1-CB11}
clusters represents one of these rare examples.17−22 Its useful-
ness stems from (i) the availability of the iodinated precursors,
e.g., [12-I-closo-1-CB11H11]−,15,18 [7-I-12-X-closo-1-CB11H10]−
(X = F, Cl, Br, OH),23 and [7,12-I2-closo-1-CB11H10]−,15 and
(ii) the broad range of Grignard reagents that can be used as
starting materials. However, the reactions often require a large
excess of the Grignard reagent, high catalyst loadings, and long
reaction times, and in most cases the yields do not exceed 60%.
Thus, development of the further chemistry and application of
the functionalized carba-closo-dodecaborate anions, which so far
are accessible solely via a Kumada-type cross-coupling reaction,
is often hampered because salts of the anions are available in
small quantities only.
RESULTS AND DISCUSSION
■
Microwave-Assisted Kumada-Type Cross-Coupling
Reactions. The microwave-assisted Pd-catalyzed cross-coupling
reaction of [12-I-closo-1-CB11H11]− (1) with Me3SiCCMgBr
results in the trimethylsilylalkynyl derivative [12-Me3SiCC-
closo-1-CB11H11]− (1a) in a yield of 85% (Scheme 1). The yield
of this reaction amounts to only 55% when it is performed
under conventional heating instead of microwave irradiation as
reported earlier.22
In addition to the improved yield of the microwave-assisted
synthesis, the reaction time is reduced from 10 days to 1−3 h,
In this contribution we report on the microwave-assisted
Kumada-type cross-coupling reaction of mono- and diiodina-
ted carba-closo-dodecaborate anions. Application of microwave
Received: December 7, 2011
Published: January 26, 2012
© 2012 American Chemical Society
2679
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
a functional group that is bonded via a carbon atom to the
antipodal boron atom in yields of up to 90%. The study
includes preparation of alkynyl, aryl, alkyl, and allyl substituents,
and the results are summarized in Table 2. In general, signi-
ficantly increased yields, shorter reaction times, lower catalyst
loadings, and a reduction of the amount of the respective
Grignard reagent were achieved in comparison to the
conventional reactions that were reported for some of the
compounds by other groups or us. For example, yields of 52%
and 54% were reported for [Me4N][12-Et-closo-1-CB11H11]
([Me4N]1l)18 and [Et4N][12-PhCC-closo-1-CB11H11]
([Et4N]1f),22 respectively, whereas the microwave-assisted
syntheses gave yields of 84% for [Et4N]1l and Cs1f.
Scheme 1. Kumada-Type Cross-Coupling Reaction of 1 To
Result in 1a as the Main Product and the Inner Salt 2 as a
Side Product
The tetraethylammonium salts of [12-Ph-closo-1-CB11H11]−
(1h), [12-(4-MeO-C6H4)-closo-1-CB11H11]− (1j), and [12-
(H2C(Me)CCC)-closo-1-CB11H11]− (1g) were character-
ized by single-crystal X-ray diffraction (Figure 1). [Et4N]1j
crystallizes as solvate with one acetone molecule per formula
unit of the [Et4N]+ salt, and the carba-closo-dodecaborate anion
has crystallographic mirror symmetry. In contrast, neither anion
1h nor anion 1j shows any symmetry in the crystal.
depending on the amount of precatalyst [PdCl2(PPh3)2]. The
amount of the Pd complex is lowered from 30 mol % to 2−3
mol %. Furthermore, 2 equiv of the Grignard reagent
Me3SiCCMgBr is sufficient, whereas as much as 14 equiv
are required to achieve complete conversion of the conventional
reaction. A comparison of the parameters of the microwave-
assisted and conventional reactions is given in Table 1.
The B12−Caryl distances in anions 1h and 1j are similar to
those reported for related {closo-1-CB11} clusters with aryl
groups bonded to the antipodal boron atom, e.g., 1.591(4) Å in
[1-(4-Me-C6H4-4-C6H4)-12-(4-Me-C6H4)-closo-CB11H10]2−.20,21
The corresponding B12−C distance and d(CC) in the alkynyl
derivative 1g are close to values derived for other {12-RC
C-closo-1-CB11} clusters, for example, in [12-PhCC-closo-1-
CB11H11]− (1f) (d(B12−C) = 1.548(2) Å, d(CC) = 1.202(2)
Å).34 The bond distances of the B−CCC(Me)CH2
fragment in 1g are similar to those described for (H2C(Me)-
CCC)(C6F5)2B(C2H4PHMes2) (d(B−C) = 1.587(3) Å,
d(CC) = 1.203(3) Å, d(C−C) = 1.435(3) Å, d(CCH2) =
1.322(4) Å, d(C−CH3) = 1.473(4) Å).35
The Kumada-type Pd-catalyzed cross-coupling reaction of
H2CCHCH2MgBr with Cs1 solely resulted in [12-H2C
CHCH2-closo-1-CB11H11]− (1n) as shown by NMR spectros-
copy (Table 2, entries 12 and 13). During aqueous workup the
allyl group partially isomerizes to a vinyl group to selectively
give [12-(trans-CH3CHCH)-closo-1-CB11H11]− (1o). Hence,
mixtures of both [Et4N]+ salts were obtained with a total yield
of 77−79%. The extent of isomerization depends on the
temperature during and the time of the aqueous workup
procedure. Thus, one of the reactions described in the
Experimental Section yielded a mixture of salts that consisted
of 94% of [Et4N]1o and 6% of [Et4N]1n (entry 12) and the
other of 16% of [Et4N]1o and 84% of [Et4N]1n (entry 13).
However, the workup conditions were not fully optimized to
exclusively yield either the allyl (1n) or the vinyl (1o) deri-
vative. In contrast to the cross-coupling reaction with
Me3SiCCMgBr to result in 1a (Scheme 1), CuI lead to a
strong acceleration of the reaction with a change of the reaction
time from 30 (entry 12) to 2.5 h (entry 13).
Table 1. Comparison of the Conventional and the
Microwave-Assisted Pd-Catalyzed Cross-Coupling Reaction
of 1 with Me3SiCCMgBr To Result in [Et4N]1a
Me3SiCC
yield
1a
MgBr
(equiv)
[PdCl2(PPh3)2]
[mol %]
yield 2
[%]
conditions
t [h]
[%]
conventional
14
30
240
55
10
heating22
a
microwave
microwave
2
2
2
3
3
1
85
85
(<1)
a
(<1)
a
Determined by 11B{1H} NMR spectroscopy.
The zwitterion 12-Ph3P-closo-1-CB11H11 (2) was identified as
a side product of the Kumada-type cross-coupling reaction
performed with [PdCl2(PPh3)2] for the first time, and it was
isolated in yields of 10% from product mixtures of conventional
reactions. Its spectroscopic and structural characterization is
presented in the successive section. The amount formed of 2
drops to less than 1% by applying microwave irradiation and
optimized conditions as evident from NMR spectroscopic
analyses of the reaction mixtures (Table 1).
Addition of CuI to the reaction mixture, which is used as a
reagent in some related Pd-catalyzed cross-coupling reactions
of iodinated boron clusters,32 did not result in a further
improvement of the reaction but leads to a strong decrease of
the reaction rate. An attempted synthesis of 1a with conditions
comparable to those of the microwave-assisted reactions listed
in Table 1 but with 10 mol % of CuI resulted in a conversion of
only 20% after 3 h.
Synthesis can easily be scaled up as demonstrated by
preparation of almost 3 g of Cs[12-HCC-closo-1-CB11H11]
(Cs1b) in a one-step synthesis starting from 5 g of Cs[12-I-
closo-1-CB11H11] (Cs1) in a yield of 78%. This synthesis
involves the reaction depicted in Scheme 1 followed by cleavage
of the trimethylsilyl group. Preparation of Cs1b starting from
Cs1 with [Et4N]1a, which was synthesized as shown in Scheme
1, as intermediate was reported earlier with an overall yield of
49%.22,33
An analogous isomerization as observed for anions 1n
and 1o was reported for preparation of [Et4N][1-Ph-12-
(trans-CH3CHCH)-closo-1-CB11H10] during aqueous work-
up under acidic conditions.21 The conventional Kumada-type
cross-coupling reaction yielded after isomerization the tetrae-
thylammonium salt of the carba-closo-dodecaborate anion in a
yield of 42%. No isomerization was found for the neutral allyl
derivative 1-Me3N-2-Ph-8-(H2CCHCH2)-closo-1-CB11H9,
which was obtained also via a cross-coupling reaction using
an allyl Grignard reagent in a yield of 82%.17
The protocol of the microwave-promoted Kumada-type
cross-coupling reaction was adopted for preparation of a variety
of other derivatives of the carba-closo-dodecaborate anion with
2680
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
Table 2. Microwave-Assisted Kumada-Type Cross-Coupling Reaction of 1, 3, and 4
a
b
c
Isolated as either Cs+ or [Et4N]+ salt. Not a fully optimized reaction. The Me3Si group was removed during workup under basic aqueous
d
e
conditions to result in the terminal alkyne. Me3SiCH2MgCl. Three mole percent of catalyst and 2 equiv of H2CCHCH2MgBr were added at the
f
beginning of the reaction, and after 24 h further 4 mol % [PdCl2(PPh3)2] and 5 equiv of H2CCHCH2MgBr were added. The allyl derivative 1o
partially isomerizes to the vinyl derivative [12-(trans-CH3CHCH)-closo-1-CB11H11]− (1p). The extent depends on the conditions of the workup
g
procedure as described in the Experimental Section. H2CCHCH2MgBr, [PdCl2(PPh3)2], and CuI were added in three equal batches.
The versatility of the novel microwave-assisted protocol is
furthermore demonstrated by preparation of a series of carba-
closo-dodecaborate anions with a functional group that is
bonded via carbon to the boron atom at the 7 position of the
cluster. The yields and conditions of these reactions that are
collected in Table 3 are similar to those described for the
analogous cross-coupling reactions starting from [12-I-closo-1-
CB11H11]− (1) in Tables 1 and 2.
In Table 3 one example for a microwave-assisted cross-
coupling reaction of the diiodinated precursor [7,12-I2-closo-1-
CB11H10]− (8) is presented as well. The conditions for prepara-
tion of [Et4N][7,12-(HCC)2-closo-1-CB11H10] ([Et4N]8a)
via [7,12-(Me3SiCC)2-closo-1-CB11H10]− are also highly im-
proved in comparison to the conventional method similar
to preparation of [12-Me3SiCC-closo-1-CB11H11]− (1a)
(Table 1).22 The yield was improved from 38% for Cs8a
(41% for the cross-coupling procedure22 and 93% for the
desilylation reaction33) to 63%.
Synthesis and Characterization of 12-Ph3P-closo-1-
CB11H11 (2). The inner salt 12-Ph3P-closo-1-CB11H11 (2),
which is the side product of all Kumada-type cross-coupling
reactions presented in Tables 1 and 2, was selectively
synthesized in a yield of 88% via a microwave-assisted Pd-
catalyzed cross-coupling reaction as shown in Scheme 2. The
precatalyst of the synthesis is [Pd(PPh3)4]. Similar to pre-
paration of the isoelectronic anionic triphenylphosphane deriv-
ative [Ph3P-closo-B12H11]−, which was described earlier,36 addi-
tion of a carbonate salt was necessary. Without either K2CO3 or
[Pd(PPh3)4] no conversion of 1 to result in 2 was observed.
However, the function of K2CO3 remains unclear. Attempted
synthesis of 2 using the same reaction conditions but with
conventional heating instead of microwave irradiation resulted
in a much slower reaction, and thus, the reaction was aborted
after a few percent of conversion.
Zwitterion 2 was characterized by multi-NMR spectroscopy
and elemental analysis. The 31P NMR signal of 2 is shifted
2681
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
Carba-closo-dodecaborate anions with different functional
groups that are bonded via carbon to the antipodal boron atom
or to one of the boron atoms of the lower belt or to both of
them are now much more easily accessible. This will facilitate
the study of their reactions and properties, for example, the
coordination chemistry of carba-closo-dodecaboranylethynido
ligands in coordination chemistry as in [{12-(Me3PAu)2CC-
closo-1-CB11H11}2].14
EXPERIMENTAL SECTION
■
1
General Methods. H, 11B, 13C, 19F, and 31P NMR spectra were
recorded at 25 °C either in CD3CN, (CD3)2CO, or toluene-d8 on a
Bruker Avance III 400 spectrometer operating at 400.17 (1H), 128.39
(11B), 100.62 MHz (13C), 376.45 MHz (19F), and 128.39 MHz (31P).
The NMR signals were referenced against TMS (1H, 13C), BF3·OEt2 in
CD3CN (11B), CFCl3 (19F), and H3PO4 (85%) in H2O (31P) as
Figure 1. Anions [12-Ph-closo-1-CB11H11]− (1h, left), [12-(4-MeO-
C6H4)-closo-1-CB11H11]− (1j, middle), and [12-(H2C(Me)CC
C)-closo-1-CB11H11]− (1g, right) in the crystals of their [Et4N]+ salts.
Selected bond lengths [Angstroms] and angles [degrees]: 1h B12−C2
1.583(2); 1j B12−C2 1.582(4), C5−O1 1.372(4), O1−C8 1.420(4),
C5−O1−C8 117.0(2); 1g B12−C2 1.545(2), C2C3 1.197(2), C3−
C4 1.431(2), C4C5 1.322(3), C4−C6 1.494(3), B12−C2C3
177.9(2), C2C3−C4 179.0(2), C3−C4C5 121.0(2), C3−C4−
C6 116.1(2), C5C4−C6 123.0(2).
external standards. Assignments of the H and 11B NMR signals are
1
supported by 11B{1H}−1H{11B} 2D37,38 and 11B{1H}−11B{1H}
COSY39,40 experiments. Infrared and Raman spectra were recorded
at room temperature on an Excalibur FTS 3500 spectrometer (Digilab,
Germany) with an apodized resolution of 2 (IR) and 4 cm−1 (Raman),
respectively. IR spectra were measured in the attenuated total
reflection (ATR) mode in the region of 4000−530 cm−1. Raman
spectra were measured using the 1064 nm excitation line of a Nd/YAG
laser on crystalline samples contained in melting point capillaries in
the region of 3500−80 cm−1. Elemental analyses (C, H, N) were
performed with a Euro EA3000 instrument (HEKA-Tech, Germany).
Chemicals. All standard chemicals were obtained from commercial
sources. Tetrahydrofuran was distilled from K/Na alloy under a
nitrogen atmosphere and stored in a flask equipped with a valve with a
PTFE stem (Young, London) over molecular sieves (4 Å) under an
argon atmosphere. The following alkynes were obtained from
commercial sources: Me3SiCCH, Apollo Scientific; Et3SiCCH,
ABCR; iPr3SiCCH, Sigma-Aldrich; nC4H9CCH, ACROS; 1-Br-4-
(Me3SiCC)-C6H4, Sigma-Aldrich. Solutions of Me3SiCCMgBr,
Et3SiCCMgBr, iPr3SiCCMgBr, and nC4H9CCMgBr in THF
(0.75 mol L−1) were prepared from the corresponding ethyne and
EtMgBr (1 mol L−1 in THF) and kept in round-bottom flasks with a
valve with a PTFE stem (Young, London) at 4 °C. The aryl Grignard
reagents were synthesized from the corresponding aryl bromide and
Mg in THF (1 mol L−1). EtMgBr (1 mol L−1 in THF), PhCCMgBr
(1 mol L−1 in THF), Me3SiCH2MgCl (1 mol L−1 in Et2O), and H2C
CHCH2MgBr (1 mol L−1 in Et2O) were obtained from Sigma-Aldrich.
H2C(Me)CCCMgBr (0.5 mol L−1 in THF) was prepared from
(Me3SiO)Me2CCCH and EtMgBr. Cs[12-I-closo-1-CB11H11]15,18
and Cs[7,12-I2-closo-1-CB11H10],15 were synthesized according to
modified literature procedures. The monoiodinated carborates Cs[7-I-
12-Hal-closo-1-CB11H10] (Hal = F, Cl, Br) were prepared as described
elsewhere.23 Cs[1-Ph-closo-1-CB11H11] was prepared from nido-B10H14
via [Et4N][6-Ph-nido-6-CB9H11].41−44 Iodination resulting in Cs[1-Ph-
12-I-closo-1-CB11H10] followed a known protocol.19,21 Cs[1-Me-12-I-
closo-1-CB11H10] was synthesized as described in the literature.18
Cesium carba-closo-1-dodecaborate was obtained from Katchem spol.
sro (Praha, Czech Republic) or synthesized from [Me3NH][nido-
B11H14]45 according to a literature procedure.46
to a lower resonance frequency than the signal of [Ph3P-
closo-B12H11]− (Table 4). The 31P−13C coupling constant of 2
1
(147 Hz) is slightly larger compared to J(31P,13C) of [Ph3P-
closo-B12H11]− (134 Hz).
A single crystal of the neutral inner salt 2 was studied by
X-ray diffraction, and a molecule in the crystal is depicted in
Figure 2. In Table 4 selected bond distances of 2 are compared
to values of [Ph3P-closo-B12H11]− and values derived from DFT
and ab initio calculations for both of them. The experimental
bond properties of the closo-boron species are well reproduced
by the DFT and (RI)-MP2 calculations, which confirms the
differences between both cluster derivatives as suggested by the
experimental data. The B−P distance in 2 of 1.944(3) Å is
slightly longer than d(B−P) in [nBu4N][Ph3P-closo-B12H11] of
1.928(2) Å. The mean value of the three phosphorus carbon
distances is slightly shorter for 2 compared to the anion, which
contrasts the trend in d(B−P). The longer B−P distance in 2 is
accompanied by a smaller B−P−C angle. The inner cluster
bond distances of 2 are close to values derived for other {closo-
1-CB11} clusters from single-crystal X-ray diffraction and theo-
retical calculations, e.g., for [12-PhCC-closo-1-CB11H11]−
(1f).22,34
SUMMARY AND CONCLUSION
■
Microwave irradiation instead of conventional heat transfer
results in a tremendous improvement of the Pd-catalyzed
Kumada-type cross-coupling reaction of mono- and diiodinated
carba-closo-dodecaborate anions. The enhancement of the
reactions includes higher yields, shorter reaction times, lower
catalyst loadings, and a reduction of the Grignard reagent.
Probably, application of microwave irradiation to other cross-
coupling reactions in the field of boron cluster chemistry will
lead to similar improvements. A first example is preparation of
the inner salt 12-Ph3P-closo-1-CB11H11 (2) that can be prepared
in 4 h in high yield from Ph3P and [12-I-closo-1-CB11H11]− (1),
whereas the reaction is very slow when conventional heat
transfer is used.
Single-Crystal X-ray Diffraction. Colorless crystals of 2 suitable
for a X-ray diffraction study were grown from toluene by slow
evaporation of the solvents. Slow uptake of diethyl ether into solutions
of [Et4N]1h, [Et4N]1j·Me2CO, and [Et4N]1g in acetone resulted in
colorless crystals. A crystal of 2 was investigated with a Stoe STADI
CCD diffractometer, and crystals of the other three substances were
studied with an Oxford Xcalibur diffractometer equipped with an EOS
detector using Mo Kα radiation (λ = 0.71073 Å). All structures were
solved by direct methods,47,48 and refinement is based on full-matrix
least-squares calculations on F2.48,49
The positions of most of the hydrogen atoms in the crystal struc-
tures were located via ΔF syntheses. The only exceptions are those of
the hydrogen atoms of the disordered acetone molecule in [Et4N]
1j·Me2CO. All non-hydrogen atoms were refined anisotropically.
2682
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
Table 3. Microwave-Assisted Kumada-Type Cross-Coupling Reaction of 5−8
a
b
Isolated either as Cs+ or [Et4N]+ salt. The Me3Si group was removed during workup under basic aqueous conditions to result in the terminal
c
d
alkyne. Not a fully optimized reaction. Three mole percent of catalyst and 3 equiv of Me3SiCCMgBr were added at the beginning of the
reaction, and after 5 h additional 3 mol % [PdCl2(PPh3)2] and 3 equiv of Me3SiCCMgBr were added.
poured into deionized water (2−10 mL per mmol cluster) after
complete conversion, and most of the THF was removed under
reduced pressure. The black residue was filtered off, and the water was
stored separately. The black residue was dissolved in a minimum
amount of CH2Cl2 and extracted twice with deionized water (2 × ∼20 mL
per mmol cluster). All water layers were combined, and the Cs+ or
[Et4N]+ salt of the respective carba-closo-dodecaborate anion was
precipitated by addition of a concentrated aqueous solution of CsCl or
[Et4N]Br (2 mmol per mmol cluster), respectively. The resulting white
precipitate was collected by filtration and dried in a vacuum.
Scheme 2. Microwave-Assisted Pd-Catalyzed Synthesis of 2
(yield 88%)
[Et4N][12-Me3SiCC-closo-1-CB11H11] ([Et4N]1a). [Et4N]1a
was prepared from Cs[12-I-closo-1-CB11H11] (200 mg, 0.50 mmol)
and Me3SiCCMgBr (1.3 mL, 1 mmol) with [PdCl2(PPh3)2]
(10 mg, 0.015 mmol) as precatalyst. Yield: 157 mg (0.43 mmol, 85%).
Spectroscopic data and results of elemental analysis have been
reported earlier.22
Most of the hydrogen atoms were refined using idealized bond lengths
as well as angles.
Calculations were carried out using the WinGX program package.50
Molecular structure diagrams were drawn with the program Diamond
3.2 g.51 Experimental details, crystal data, and CCDC numbers are
collected in Table 5. Supplementary crystallographic data for this
publication are deposited in the Supporting Information or can be
obtained free of charge from the Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Cs[12-HCC-closo-1-CB11H11] (Cs1b). Cs[12-I-closo-1-CB11H11]
(5.00 g, 12.44 mmol), Me3SiCCMgBr (33 mL, 25 mmol), and
[PdCl2(PPh3)2] (262 mg, 0.375 mmol) were used. [Et4N]1a was not
dried after precipitation but immediately treated with hydrochloric
acid (50 mL, 2 mol L−1) and diethyl ether (200 mL). The ethereal
layer was separated after complete dissolution of the tetraethylammo-
nium salt, and the aqueous phase was extracted three times with
diethyl ether (3 × 100 mL). The combined organic phases were dried
with MgSO4. The magnesium sulfate was filtered off, and a saturated
aqueous solution of cesium carbonate (5 g, 15.3 mmol) was added to
the solution. Ether was removed using a rotary evaporator, and
acetone (200 mL) was added to the remaining solid. The solution was
dried with Cs2CO3 and filtered, and most of the solvent was removed
with a rotary evaporator to result in a concentrated solution of Cs1b
(5 mL). The cesium salt was precipitated by addition of chloroform
(300 mL), filtered, and dried in a vacuum. Yield: 2.91 g (9.67 mmol,
78%). Spectroscopic data and results of the elemental analysis for
Cs1b have been reported earlier.33
Attempted Synthesis of the Salt of [12-Me3SiCC-closo-1-
CB11H11]− (1a) in the Presence of CuI. The reaction was performed
as described for the general procedure with Cs[12-I-closo-1-CB11H11]
(200 mg, 0.50 mmol) and Me3SiCCMgBr (1.3 mL, 1 mmol) with
[PdCl2(PPh3)2] (10 mg, 0.015 mmol), but CuI (10 mg, 0.050 mmol)
was added. After 3 h only 20% of the starting material had reacted to
1a and small amounts of 2. Because of the very slow conversion the
reaction was discontinued.
Quantum Chemical Calculations. Density functional calcula-
tions (DFT)52 were carried out using Becke’s three-parameter hybrid
functional and the Lee−Yang−Parr correlation functional
(B3LYP)53−55 using the Gaussian03 program suite.56 Geometries
were optimized, and energies were calculated with the 6-311++G(d,p)
basis sets. Diffuse functions were incorporated because improved
energies are obtained for anions.57 Structures represent true minima
with no imaginary frequency on the respective hypersurface. Geo-
metries were optimized at the second-order Møller−Plesset pertur-
bation (MP2) level of theory also using the resolution-of-the-identity
approximation [(RI)-CC2 module]58 in combination with the def2-
TZVPP basis sets and auxiliary bases.59
General Procedure for the Microwave-Assisted Cross-
Coupling Reactions. The iodinated carba-closo-dodecaborate and
[PdCl2(PPh3)2] was dissolved in dry THF (2−10 mL per mmol
cluster) under an Ar atmosphere in a glass finger (70 mL) equipped
with a valve with a PTFE stem (Young, London) and fitted with a
magnetic stirring bar. A solution of the respective Grignard reagent in
THF (0.75−1.0 mmol mL−1) was added via syringe. The reaction
mixture was heated to 55 °C by microwave irradiation (CEM Discover
S-Klasse Plus (SP)), and the progress of the reaction was periodically
checked by 11B{1H} NMR spectroscopy. The reaction mixture was
2683
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
a
Table 4. Comparison of Selected Experimental and Calculated Data of 12-Ph3P-closo-1-CB11H11 (2) and [Ph3P-closo-
b c
,
B12H11]−
12-Ph3P-closo-1-CB11H11 (2)
d(Ccluster−B d(B2/3/4/5/6 d(B2/3/4/5/6− d(B7/8/9/10/11 d(B7/8/9/10/11
d
method δ(31P) 1J(31P,11B) d(B12−P) d(P−Cipso
)
∠(B12−P−C) 2/3/4/5/6) −B2/3/4/5/6) B7/8/9/10/11) −B7/8/9/10/11)
−B12)
exptl
2.3
147
1.944(3)
1.971
1.808(2)
112.58(11)
113.04
1.696(4)
1.705
1.766(5)
1.782
1.765(5)
1.770
1.786(4)
1.798
1.771(4)
1.779
B3LYP
MP2
1.837
1.791
1.904
112.93
1.699
1.778
1.766
1.794
1.768
−
[Ph3P-closo-B12H11]
d(B
7/8/9/10/11 d(B7/8/9/10/11− d(B2/3/4/5/6−B d(B2/3/4/5/6− d(B1−B2/
d
method δ(31P) 1J(31P,11B) d(B1−P) d(P−Cipso
)
∠(B1−P−C)
−B12)
B7/8/9/10/11)
7/8/9/10/11)
B2/3/4/5/6)
3/4/5/6)
exptle
B3LYP
MP2
6.8
134
1.928(2)
1.949
1.816(2)
113.48(9)
114.38
1.787(4)
1.784
1.787(4)
1.788
1.778(3)
1.779
1.796(3)
1.799
1.780(3)
1.775
1.845
1.795
1.869
114.27
1.761
1.786
1.775
1.796
1.761
a
b
Methods: B3LYP/6-311++G(d,p) and (RI)-MP2/def2-TZVPP. Distances in Angstroms, angles in degrees, chemical shifts in parts per million,
and coupling constants in Hertz. Mean values for C5v symmetry of the clusters. Mean value. [nBu4N][Ph3P-closo-B12H11].36
c
d
Figure 2. (a) Molecule of 12-Ph3P-closo-1-CB11H11 (2) in the crystal (displacement ellipsoids at the 35% probability level). (b) Calculated structures
at the B3LYP/6-311++G(d,p) level of theory, and labeling schemes for the cluster atoms of 2 and [Ph3P-closo-B12H11]−.
[Et4N][12-Et3SiCC-closo-1-CB11H11] ([Et4N]1c). [Et4N]1c was
synthesized from Cs[12-I-closo-1-CB11H11] (200 mg, 0.50 mmol) and
Et3SiCCMgBr (1.3 mL, 1 mmol) with [PdCl2(PPh3)2] (10 mg,
0.015 mmol). Yield: 145 mg (0.35 mmol, 70%). NMR data for anion
1c: 1H{11B} NMR ((CD3)2CO, δ ppm): 2.14 (sextet, 1H, 3J(1H,1H) =
3.3 Hz, CHcluster), 1.71 (s, 5H, BH7−11), 1.61 (s, 5H, BH2−6), 0.92
(t, 9H, 3J(1H,1H) = 7.9 Hz, 1J(13C,1H) = 125.8 Hz, CH3), 0.45 (q, 6H,
B2−6). IR/Raman (cm−1): 2116 cm−1 (ν(CC)). MALDI-MS m/z
(isotopic abundance > 60) calcd for 1d ([C12H32B11Si]−): 322 (67%),
323 (100%), 324 (70%). Found: 322 (74%), 323 (100%), 324 (79%).
Anal. Calcd for C12H32B11CsSi: C, 31.59; H, 7.07. Found: C, 31.76; H,
7.26.
Cs[12-nC4H9CC-closo-1-CB11H11] (Cs1e). Cs1e was prepared
from Cs[12-I-closo-1-CB11H11] (500 mg, 1.25 mmol) and nC4H9C
CMgBr (5 mL, 3.75 mmol) with [PdCl2(PPh3)2] (25 mg, 0.035
mmol). Yield: 460 mg (1.41 mmol, 70%). 1H{11B} NMR ((CD3)2CO,
δ ppm): 2.10 (sextet, 1H, 3J(1H,1H) = 3.4 Hz, CHcluster), 1.99 (tm, 2H,
3J(1H,1H) = 6.9 Hz, CC−CH2), 1.67 (s, 5H, BH7−11), 1.60 (s, 5H,
1
3J(1H,1H) = 7.9 Hz, J(13C,1H) = 118.4 Hz, SiCH2). 13C{1H} NMR
((CD3)2CO, δ ppm): 124.59 (q, 1C, 1J(13C,11B) = 98.9 Hz,
2
13
B12−13CC), 94.01 (q, 1C, J(13C,11B) = 15.7 Hz, B12−C C),
48.75 (s, 1C, Ccluster), 7.82 (s, 3C, CH3), 5.44 (s, 3C, J(29Si,13C) =
1
55.8 Hz, 1J(13C,13C) = 31.6 Hz, Si13CH21). 11B NMR ((CD3)2CO,
3
BH2−6), 1.32 (m, 4H, CH2CH2), 0.83 (tm, 3H, J(1H,1H) = 7.1 Hz,
δ ppm): −7.4 (s, 1B, B12), −12.2 (d, 5B, J(11B,1H) = 139, B7−11),
2
CH3). 13C{1H} NMR ((CD3)2CO, δ ppm): 93.54 (q, 1C, J(13C,11B) =
−16.7 (d, 5B, J(11B,1H) = 151 Hz, B2−6). IR/Raman (cm−1): 2114
1
13
18.6 Hz, B12−C C), 91.42 (q, 1C, 1J(13C,11B) = 104.2 Hz,
cm−1 (ν(CC)). MALDI-MS m/z (isotopic abundance > 60) calcd
for 1c ([C9H26B11Si]−): 280 (75%), 281 (100%), 282 (80%). Found:
280 (80%), 281 (100%), 282 (93%). Anal. Calcd for C17H46B11NSi: C,
49.61; H, 11.27; N, 3.40. Found: C, 48.65; H, 11.27; N, 3.36.
Cs[12-iPr3SiCC-closo-1-CB11H11] (Cs1d). Cs[12-I-closo-1-
CB11H11] (1 g, 2.49 mmol), [PdCl2(PPh3)2] (50 mg, 0.075 mmol),
and iPr3SiCCMgBr (6.5 mL, 5 mmol) were used. Yield: 700 mg
(1.54 mmol, 61%). 1H{11B} NMR ((CD3)2CO, δ ppm): 1.59 (s, 10H,
B12−13CC), 47.92 (s, 1C, Ccluster), 32.36 (s, 1C, CH2), 22.51 (s, 1C,
CH2), 20.14 (s, 1C, CH2), 13.90 (s, 1C, CH3). 11B NMR ((CD3)2CO,
δ ppm): −6.7 (s, 1B, B12), −12.34 (d, 5B, 1J(11B,1H) = 138 Hz B7−11),
−16.9 (d, 5B, 1J(11B,1H) = 151 Hz, B2−6). IR/Raman (cm−1): 2188 cm−1
(ν(CC)). MALDI-MS m/z (isotopic abundance > 60) calcd for 1e
([C7H20B11]−): 222 (75%), 223 (100%), 224 (80%). Found: 222 (81%),
223 (100%), 224 (88%). Anal. Calcd for C7H20B11Cs: C, 23.61; H, 5.66.
Found: C, 23.58; H, 5.51.
BH2−11), 2.26 (s, 1H, CHcluster), 1.02 (d, 18H, J(13C,1H) = 125 Hz,
1
Cs[12-PhCC-closo-1-CB11H11] (Cs1f). Cs1f was synthesized
from Cs[12-I-closo-1-CB11H11] (200 mg, 0.50 mmol) and PhC
CMgBr (1.3 mL, 1 mmol) with [PdCl2(PPh3)2] (10 mg, 0.015 mmol).
Yield: 158 g (0.42 mmol, 84%). Spectroscopic data and results of
elemental analysis have been published elsewhere.22
[Et4N][12-(H2C(Me)CCC)-closo-1-CB11H11] ([Et4N]1g). Cs-
[12-I-closo-1-CB11H11] (500 mg, 1.25 mmol), [PdCl2(PPh3)2] (75 mg,
0.110 mmol), and H2C(Me)CCCMgBr (7.6 mL, 3.8 mmol) were
3J(1H,1H) = 6.6 Hz, CH3), 0.95 (heptet, 3H, J(1H,1H) = 6.6 Hz,
3
SiCH). 13C{1H} NMR ((CD3)2CO, δ ppm): 125.82 (q, 1C,
1J(13C,11B) = 98 Hz, B12−13CC), 92.95 (q, 1C, 2J(13C,11B) = 15 Hz,
B12−C C), 48.70 (s, 1C, Ccluster), 19.18 (s, 6C, J(13C,13C) = 31
13
2
Hz, CH3), 12.32 (s, 3C, J(29Si,13C) = 56 Hz, J(13C,13C) = 31 Hz,
1
2
SiC). 11B NMR ((CD3)2CO, δ ppm): −7.6 (s, 1B, B12), −12.3 (d, 5B,
1J(11B,1H) = 139 Hz, B7−11), −16.7 (d, 5B, J(11B,1H) = 152 Hz,
1
2684
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
Table 5. Selected Crystal Data and Details of the Refinement of the Crystal Structures of 12-Ph3P-closo-1-CB11H11 (2),
[Et4N][12-Ph-closo-1-CB11H11] ([Et4N]1h), [Et4N][12-(4-MeO-C6H4)-closo-1-CB11H11]·Me2CO ([Et4N]1j·Me2CO), and
[Et4N][12-(H2C(Me)CCC)-closo-1-CB11H11] ([Et4N]1g)
2
[Et4N]1h
[Et4N]1j·Me2CO
[Et4N]1g
empirical formula
fw
C19H26B11P
404.28
C15H36B11N
349.36
C19H44B11NO2
437.46
C14H36B11N
337.35
T/K
290
290
290
290
cryst syst
space group
a/Å
triclinic
orthorhombic
Pbca
orthorhombic
Cmca
orthorhombic
Pbca
P1
̅
7.979(3)
10.106(4)
14.852(6)
85.88(3)
86.36(3)
75.45(3)
1154.9(8)
2
10.2163(3)
17.0365(6)
26.2239(10)
16.739(3)
32.500(7)
10.328(2)
10.7180(7)
16.8947(9)
24.9893(14)
b/Å
c/Å
α/deg
β/deg
γ/deg
volume/Å3
4564.3(3)
8
5618.6(19)
8
4525.0(5)
8
Z
−3
D
calcd/Mg m
1.163
1.017
1.034
0.990
−1
μ/mm
0.124
0.050
0.057
0.049
F(000)
420
1504
1888
1456
no. of collected reflns
no. of unique reflns, R(int)
no. of params/restraints
R1 (I > 2σ(I))
wR2 (all)
15883
56490
23820
19119
4048, 0.070
291/0
3986, 0.065
344/0
2569, 0.063
299/0
3942, 0.045
303/1
0.055
0.058
0.073
0.050
0.130
0.110
0.146
0.094
GOF on F2
1.008
1.036
1.915
1.063
largest diff. peak/hole/e Å−3
0.311/−0.420
790764
0.198/−0.179
851853
0.377/−0.349
851854
0.155/−0.172
851852
CCDC no.
1
used. Yield: 274 mg (0.81 mmol, 65%). NMR data for anion 1g.
1H{11B} NMR ((CD3)2CO, δ ppm): 4.91 (m, 2H, CCH2), 2.17
B2−6), 0.18 (s, 9H, J(13C,1H) = 118.7 Hz, CH3). 13C{1H} NMR
((CD3)2CO, δ ppm): 149.06 (q, 1J(13C,11B) ≈ 75 Hz, 1C, Cipso),
135.18 (s, 1C, Cpara), 133.27 (s, 2C, Ph), 131.90 (s, 2C, Ph), 47.18 (s,
1C, Ccluster), −0.85 (s, 3C, CH3). 11B NMR ((CD3)2CO, δ ppm): 2.5
3
(sextet, 1H, J(1H,1H) = 3.1 Hz, CHcluster), 1.74 (s, 5H, BH7−11),
4
1.73 (pseudo triplet, 3H, J(1H,1H) ≈ 1.2 Hz, CH3), 1.64 (s, 5H,
(s, 1B, B12), −12.49 (d, 5B, J(11B,1H) = 138 Hz, B7−11), −16.5 (d,
1
BH2−6). 13C{1H} NMR ((CD3)2CO, δ ppm): 130.26 (s, 1C, 13C
5B, 1J(11B,1H) = 151 Hz, B2−6). MALDI-MS m/z (isotopic
abundance > 60) calcd for 1i ([C10H24B11Si]−): 290 (75%), 291
(100%), 292 (80%). Found: 290 (78%), 291 (100%), 292 (83%).
Anal. Calcd for C10H24B11SiCs: C, 28.31; H, 5.70. Found: C, 29.02; H,
5.73.
1
CH2), 118.03 (s, 1C, CH2), 102.35 (q, 1C, J(13C,11B) = 103.3 Hz,
B12−13C≡C), 94.87 (q, 1C, 2J(13C,11B) = 19.1 Hz, B12−C≡13C),
48.80 (s, 1C, CHcluster), 24.39 (s, 1C, CH3). 11B NMR ((CD3)2CO,
δ ppm): −6.9 (s, 1B, B12), −12.3 (d, 5B, 1J(11B,1H) = 138 Hz, B7−11),
1
−16.7 (d, 5B, J(11B,1H) = 151 Hz, B2−6). IR/Raman (cm−1): 2170
cm−1 (ν(CC)), 1601 (ν(CC)). MALDI-MS m/z (isotopic
abundance > 60) calcd for 1g ([C6H16B11]−): 206 (75%), 207
(100%), 208 (80%). Found: 206 (96%), 207 (100%), 208 (99%).
Anal. Calcd for C14H36B11N: C, 49.84; H, 10.75; N, 4.15. Found: C,
46.61; H, 10.38; N, 4.39.
[Et4N][12-(4-MeO−C6H4)-closo-1-CB11H11] ([Et4N]1j). Cs[12-I-
closo-1-CB11H11] (200 mg, 0.50 mmol), [PdCl2(PPh3)2] (10 mg, 0.015
mmol), 4-MeO-C6H4MgBr (1 mL, 1 mmol) were used. Yield: 141 mg
(0.37 mmol, 74%). NMR data for anion 1j. 1H{11B} NMR
((CD3)2CO, δ ppm): 7.30−7.26 (m, 2H, Ph), 6.63−6.59 (m, 2H,
Ph), 3.68 (s, 3H, J(13C,1H) = 143.0 Hz, OCH3), 2.21 (sextet, 1H,
1
[Et4N][12-Ph-closo-1-CB11H11] ([Et4N]1h). [Et4N]1h was pre-
pared from Cs[12-I-closo-1-CB11H11] (100 mg, 0.25 mmol) and
PhMgBr (0.8 mL, 0.8 mmol) with [PdCl2(PPh3)2] (5 mg, 0.007
mmol). Yield: 66 mg (0.19 mmol, 75%). NMR data for anion 1h.
1H{11B} NMR ((CD3)2CO, δ ppm): 7.41−7.39 (m, 2H, Ph), 7.02−
6.90 (m, 3H, Ph), 2.22 (sextet, 1H, 3J(1H,1H) = 3.3 Hz, CHcluster), 1.79
(s, 5H, BH7−11), 1.73 (s, 5H, BH2−6). 13C{1H} NMR ((CD3)2CO,
3J(1H,1H) = 3.2 Hz, CHcluster), 1.76 (s, 5H, BH7−11), 1.72 (s, 5H,
BH2−6). 13C{1H} NMR ((CD3)2CO, δ ppm): 158.51 (s, 1C, Cpara),
139.67 (q, 1C, 1J(13C,11B) ≈ 72 Hz, Cipso), 134.43 (s, 2C, Ph), 112.59
(s, 2C, Ph), 55.08 (s, 1C, OCH3), 46.65 (s, 1C, Ccluster). 11B NMR
((CD3)2CO, δ ppm): 2.6 (s, 1B, B12), −12.5 (d, 5B, 1J(11B,1H) = 136
Hz, B7−11), −16.6 (d, 5B, 1J(11B,1H) = 150 Hz, B2−6). MALDI-MS
m/z (isotopic abundance > 60) calcd for 1j ([C8H18B11O]−): 248
(75%), 249 (100%), 250 (80%). Found: 248 (84%), 249 (100%), 250
(95%). Anal. Calcd for C16H38B11NO: C, 50.65; H, 10.10; N, 3.69.
Found: C, 50.45; H, 10.34; N, 3.68.
1
δ ppm): 148.28 (q, 1C, J(13C,11B) = 74.9 Hz, Cipso), 133.65 (s, 2C,
Ph), 126.82 (s, 2C, Ph), 125.20 (s, 1C, Cpara), 47.10 (s, 1C, Ccluster).
11B NMR ((CD3)2CO, δ ppm): 2.70 (s, 1B, B12), −12.51 (d, 5B,
1
1J(11B,1H) = 136 Hz, B7−11), −16.6 (d, 5B, J(11B,1H) = 150 Hz,
[Et4N][12-(4-HCC−C6H4)-closo-1-CB11H11] ([Et4N]1k). Cs[12-
I-closo-1-CB11H11] (1 g, 2.5 mmol), [PdCl2(PPh3)2] (50 mg, 0.075
mmol), and 4-Me3SiCC−C6H4MgBr (5 mL, 5 mmol) were used.
The trimethylsilyl group was removed under basic aqueous conditions
during workup. Yield: 837 mg (2.24 mmol, 90%). NMR data for anion
B2−6). MALDI-MS m/z (isotopic abundance > 60) calcd for 1h
([C7H16B11]−): 218 (75%), 219 (100%), 220 (80%). Found: 218
(89%), 219 (100%), 220 (94%). Anal. Calcd for C15H36B11N: C,
51.57; H, 10.39; N, 4.01. Found: C, 48.83; H, 10.43; N, 4.01.
Cs[12-(4-Me3Si−C6H4)-closo-1-CB11H11] (Cs1i). The starting
materials were Cs[12-I-closo-1-CB11H11] (200 mg, 0.50 mmol),
[PdCl2(PPh3)2] (10 mg, 0.015 mmol), and 4-Me31Si−C6H4MgBr
(1 mL, 1 mmol). Yield: 155 mg (0.36 mmol, 73%). H{11B} NMR
((CD3)2CO, δ ppm): 7.40−7.18 (m, 4H, Ph), 2.22 (sextet, 1H,
3J(1H,1H) = 3.6 Hz, CHcluster), 1.80 (s, 5H, B7−11), 1.73 (s, 5H,
1k. H{11B} NMR (CD3CN, δ ppm): 7.40−7.35 (m, 2H, Ph), 7.15−
1
7.08 (m, 2H, Ph), 3.42 (s, 1H, CCH), 2.24 (sextet, 1H, 3J(1H,1H) ≈
3.5 Hz, CHcluster), 1.78 (s, 5H, BH7−11), 1.74 (s, 5H, BH2−6).
13C{1H} NMR (CD3CN, δ ppm): 150.10 (q, 1C, J(13C,11B) = 73.4
1
Hz, Cipso), 133.56 (s, 2C, Ph), 130.42 (s, 2C, Ph), 118.92 (s, 1C,
Cpara), 85.48 (s, 1C, Ph−13CCH), 77.37 (d, 1C, Ph−C≡13CH),
2685
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
1
47.52 (s, 1C, Ccluster). 11B NMR (CD3CN, δ ppm): 2.0 (s, 1B, B12),
−12.5 (d, 5B, 1J(11B,1H) = 137 Hz, B7−11), −16.5 (d, 5B, 1J(11B,1H) =
150 Hz, B2−6). IR/Raman (cm−1): 2105 cm−1 (ν(CC)). MALDI-MS
m/z (isotopic abundance > 60) calcd for 1k ([C9H16B11]−): 242 (75%),
243 (100%), 244 (80%). Found: 242 (62%), 243 (100%), 244 (70%).
Anal. Calcd for C9H16B11Cs: C, 28.75; H, 4.29. Found: C, 28.85;
H, 4.05.
(d, 2B, J(11B,1H) = 131 Hz, B8 + 11), ∼−15 (s, 1B, B7), −15.2 (d,
2B, J(11B,1H) = 162 Hz, B9 + 10), −18.4 (d, 2B, J(11B,1H) = 159 Hz,
B2 + 3), −20.1 (d, 3B, 1J(11B,1H) = 157 Hz, B4−6). 19F NMR
((CD3)2CO, δ ppm): −191.44 (q, 1J(19F,11B) = 59 Hz). IR/Raman (cm−1):
1
1
−1
2066 cm (ν(CC)). MALDI-MS m/z (isotopic abundance > 60)
−
calcd for 7a ([C3H11B11F] ): 184 (74%), 185 (100%), 186 (80%).
Found: 184 (68%), 185 (100%), 186 (72%). Anal. Calcd for
C11H31B11NF: C, 41.91; H, 9.91; N, 4.44. Found: C, 41.211; H, 9.88;
N, 4.45.
[Et4N][12-Et-closo-1-CB11H11] ([Et4N]1l). The starting materials
were Cs[12-I-closo-1-CB11H11] (200 mg, 0.50 mmol), [PdCl2(PPh3)2]
(30 mg, 0.045 mmol), and EtMgBr (1 mL, 1 mmol). Yield: 126 mg
(0.42 mmol, 84%). NMR data for anion 1l. 1H{11B} NMR
((CD3)2CO, δ ppm): 2.07 (s, 1H, CHcluster), 1.59 (s, 5H, BH7−11),
[Et4N][7-HCC-12-Cl-closo-1-CB11H10] ([Et4N]6a). Cs[12-I-
closo-1-CB11H11] (200 mg, 0.46 mmol), [PdCl2(PPh3)2] (10 mg,
0.015 mmol), and Me3SiCCMgBr (1.3 mL, 1 mmol) were used.
The trimethylsilyl group was removed under basic aqueous conditions
during workup. Yield: 270 mg (0.81 mmol, 70%). NMR data for anion
6a. 1H{11B} NMR ((CD3)2CO, δ ppm): 2.18 (sextet, 1H, 1J(1H,1H) =
3.6 Hz, CHcluster), 2.01 (s, 1H, B7−CCH), 1.87 (s, 2H, BH8 + 11),
1.80 (s, 4H, BH2 + 3+9 + 10), 1.57 (s, 3H, BH4 + 6), 1.53 (s, 1H,
BH5). 13C{1H} NMR ((CD3)2CO, δ ppm): 93.00 (q, 1C, 1J(13C,11B) =
3
1
1.53 (s, 5H, BH2−6), 0.75 (t, 3H, J(1H,1H) = 7.8 Hz, J(13C,1H) =
124.0 Hz, CH3), 0.49 (q, 2H, 3J(1H,1H) = 7.8 Hz, 1J(13C,1H) = 117.4
Hz, CH2). 13C{1H} NMR ((CD3)2CO, δ ppm): 45.28 (d, 1C, Ccluster),
14.66 (s, 1C, CH3), 12.95 (q, 1C, J(13C,11B) = 62.0 Hz, BCH2). 11B
1
NMR ((CD3)2CO, δ ppm): 4.0 (s, 1B, B12), −12.71 (d, 5B, J(11B,
1
1H) = 135 Hz, B2−6), −16.9 (d, 5B, J(11B,1H) = 149 Hz, B7−11).
1
−
105.1 Hz, B7−13CCH), 82.28 (q, 1C, J(13C,11B) = 19.3 Hz, B7−
2
MALDI-MS m/z (isotopic abundance > 60) calcd for 1l ([C3H16B11] ):
C CH), 42.55 (s, 1C, Ccluster). 11B NMR ((CD3)2CO, δ ppm): 4.0 (s,
13
170 (75%), 171 (100%), 172 (80%). Found: 170 (88%), 171 (100%),
172 (92%). Anal. Calcd for C11H36B11N: C, 43.85; H, 12.04; N, 4.65.
Found: C, 43.43; H, 12.30; N, 4.61.
1B, B12), −11.7 (d, 2B, J(11B,1H) = 148 Hz, B8 + 11), −12.7 (d, 2B,
1
B9 + 10), ∼−12.7 (s, 1B, B7), −16.7 (d, 2B, J(11B,1H) = 160 Hz,
1
B2 + 3), ∼−17 (d, J(11B,1H) = overlapped, 1B, B5), −18.1 (d, 2B,
1
[Et4N][12-Me3SiCH2-closo-1-CB11H11] ([Et4N]1m). Cs[12-I-closo-
1-CB11H11] (200 mg, 0.50 mmol), [PdCl2(PPh3)2] (10 mg, 0.015
mmol), and Me3SiCCMgBr (1.3 mL, 1 mmol) were used. Yield:
1J(11B,1H) = 145 Hz, B4−6). IR/Raman (cm ): 2065 cm (ν(CC)).
MALDI-MS m/z (isotopic abundance > 60) calcd for 6a
([C3H11B11Cl]−): 200 (75%), 201 (100%), 202 (80%). Found: 200
(76%), 201 (100%), 202 (86%). Anal. Calcd for C11H31B11ClN: C, 39.83;
H, 9.42; N, 4.22. Found: C, 40.44; H, 9.99; N, 3.69.
−1
−1
1
144 mg (0.40 mmol, 80%). NMR data for anion 1m. H{11B} NMR
((CD3)2CO, δ ppm): 2.02 (s, 1H, CHcluster), 1.58 (s, 10H, BH2−11),
0.02 (s, 2H, CH2), −0.23 (s, 9H, CH3). 13C{1H} NMR ((CD3)2CO,
1
δ ppm): 44.88 (s, 1C, Ccluster), 8.63 (q, 1C, J(13C,11B) = 58.3 Hz,
[Et4N][7-(4-HCC−C6H4)-12-Cl-closo-1-CB11H10] ([Et4N]6b).
Cs[12-I-closo-1-CB11H11] (200 mg, 0.46 mmol), [PdCl2(PPh3)2]
(10 mg, 0.015 mmol), and 4-Me3SiCC−C6H4MgBr (0.7 mL,
0.7 mmol) were used as starting materials. The trimethylsilyl group
was removed under basic aqueous conditions during workup. Yield:
CH2), 1.05 (s, 3C, 1J(29Si,13C) = 49.0 Hz, CH3). 11B NMR
1
((CD3)2CO, δ ppm): 2.3 (s, 1B, B12), −12.0 (d, 5B, J(11B,1H) =
134 Hz, B2−6), −16.82 (d, 5B, 1J(11B,1H) = 149 Hz, B7−11).
MALDI-MS m/z (isotopic abundance > 60) calcd for 1m
([C5H22B11Si]−): 228 (71%), 229 (100%), 230 (89%). Found: 228
(64%), 229 (100%), 230 (90%). Anal. Calcd for C13H42B11NSi: C,
43.43; H, 11.78; N, 3.89. Found: C, 42.93; H, 12.26; N, 3.77.
130 mg (0.32 mmol, 70%). NMR data for anion 6b. H{11B} NMR
1
((CD3)2CO, δ ppm): 7.65−7.55 (m, 2H, Ph), 7.30−7.20 (m, 2H, Ph),
3.46 (s, 1H, Ph−CCH), 2.31 (sextet, 1H, 3J(1H,1H) = 3.4 Hz,
CHcluster), 2.00 (s, 2B, BH9 + 10), 1.91 (s, 2B, BH8 + 11), 1.85 (s, 2B,
BH2 + 3), 1.67 (s, 2B, BH4 + 6), 1.62 (s, 1B, BH5). 13C{1H} NMR
[Et4N][1-Me-12-HCC-closo-1-CB11H10] ([Et4N]3a). Prepared
from Cs[1-Me-12-I-closo-1-CB11H10] (400 g, 0.96 mmol) and
Me3SiCCMgBr (4 mL, 3 mmol) with [PdCl2(PPh3)2] (35 mg,
0.050 mmol). The trimethylsilyl group was removed under basic
aqueous conditions during workup. Yield: 240 mg (0.75 mmol, 80%).
NMR data for anion 3a: 1H{11B} NMR ((CD3)2CO, δ ppm): 1.89 (s,
1H, CCH), 1.71 (s, 10H, BH2−11), 1.48 (s, 3H, CH3). 13C{1H}
NMR ((CD3)2CO, δ ppm): 96.63 (q, 1C, 1J(13C,11B) = 96.0 Hz,
((CD3)2CO, δ ppm): 145.76 (q, 1C, J(13C,11B) = 73.0 Hz, Cipso),
1
134.82 (s, 2C, Ph), 130.64 (s, 2C, Ph), 119.75 (s, 1C, Cpara), 85.33 (s,
1C, Ph−13CCH), 77.76 (s, 1C, Ph−C CH), 43.83 (s, 1C,
13
Ccluster). 11B NMR ((CD3)2CO, δ ppm): δ = 4.1 (s, 1B, B12), −4.4 (s,
1B, B7), −12.4 (d, 4B, J(11B,1H) = 138 Hz, B8−11), −16.9 (d, 2B,
1
1J(11B,1H) = 157, B2 + 3), −18.2 (d, 2B, J(11B,1H) = 133, B4 + 6),
1
2
13
B12−13CC), 81.85 (q, 1C, J(13C,11B) = 16.8 Hz, B12−C C),
−19.0 (d, 1B, J(11B,1H) = 154 Hz, B5). IR/Raman (cm ): 2104 cm−1
(ν(CC)). MALDI-MS m/z (isotopic abundance > 60) calcd for 6b
([C9H15B11Cl]−): 276 (75%), 277 (100%), 278 (80%). Found: 276
(74%), 277 (100%), 278 (93%), 279 (75%). Anal. Calcd for C17H35N
B11Cl: C, 50.07; H, 8.65; N, 3.43. Found: C, 44.95; H, 8.65; N, 3.51.
[Et4N][7-HCC-12-Br-closo-1-CB11H10] ([Et4N]7a). Cs[12-I-
closo-1-CB11H11] (50 mg, 0.1 mmol), [PdCl2(PPh3)2] (3 mg, 0.004
mmol), and Me3SiCCMgBr (0.5 mL, 0.38 mmol) were used. The
trimethylsilyl group was removed under basic aqueous conditions
during workup. Yield: 25 mg (0.07 mmol, 66%). NMR data for anion
7a. 1H{11B} NMR ((CD3)2CO, δ ppm): 2.34 (sextet, 1H, 3J(1H,1H) =
3.4 Hz, CHcluster), 2.02 (s, 1H, CCH), 1.94 (s, 2H, BH8 + 11), 1.89
(s, 2H, BH9 + 10), 1.85 (s, 2H, BH4 + 6), 1.68 (s, 1B, BH5), 1.62 (s,
2H, BH2 + 3). 13C{1H} NMR ((CD3)2CO, δ ppm): 93.45 (q, 1C,
1J(13C,11B) = 105.4 Hz, B7−13CCH), 82.13 (q, 1C, 2J(13C,11B) =
1
−1
62.72 (s, 1C, Ccluster), 27.27 (s, 1C, CH3). 11B NMR ((CD3)2CO,
δ ppm): −11.3 (s, 1B, B12), −11.9 (d, 5B, J(11B,1H) = 147 Hz,
1
B7−11), −13.1 (d, 5B, 1J(11B,1H) = 152 Hz, B2−6). IR/Raman
(cm−1): 2066 cm−1 (ν(CC)). MALDI-MS m/z (isotopic abun-
dance > 60) calcd for 3a ([C4H14B11]−): 180 (75%), 181 (100%), 182
(85%). Found: 180 (77%), 181 (100%), 182 (84%). Anal. Calcd for
C12H34B11N: C, 46.29; H, 11.01; N, 4.50. Found: C, 45.72; H, 11.22;
N, 3.69.
[Et4N][1-Ph-12-Me3SiCC-closo-1-CB11H10] ([Et4N]4a). [Et4N]
4a was synthesized from Cs[1-Ph-12-I-closo-1-CB11H11] (220 mg, 0.46
mmol) and Me3SiCCMgBr (1.84 mL, 1.38 mmol) with
[PdCl2(PPh3)2] (16 mg, 0.023 mmol). Yield: 120 mg (0.27 mmol,
58%). Spectroscopic data and results of elemental analysis have been
reported earlier.22
[Et4N][7-HCC-12-F-closo-1-CB11H10] ([Et4N]5a). [Et4N]5a
was prepared from Cs[12-I-closo-1-CB11H11] (420 mg, 0.68 mmol)
and Me3SiCCMgBr (1.3 mL, 1 mmol) with [PdCl2(PPh3)2]
(10 mg, 0.015 mmol). The trimethylsilyl group was removed under basic
aqueous conditions during workup. Yield: 110 mg (0.35 mmol, 73%).
NMR data for anion 5a. 1H{11B} NMR ((CD3)2CO, δ ppm): 2.04 (s, 1H,
CHcluster), 2.02 (s, 1H, B7−CCH), 1.78 (s, 2H, BH8 + 11), 1.67
(s, 4H, BH2 + 3+9 + 10), 1.44 (s, 3H, BH4−5). 13C{1H} NMR
19.3 Hz, B7−C CH), 44.59 (d, 1C, Ccluster). 11B NMR ((CD3)2CO,
13
δ ppm): −2.5 (s, 1B, B12), −11.3 (d, 2B, J(11B,1H) = 141 Hz, B8 +
1
11), −12.7 (d, 3B, 1J(11B,1H) ≈ 142 Hz, B9 + 10), ∼−12.7 (s, 1B, B7),
−16.3 (d, 2B, 1J(11B,1H) = 156 Hz, B2 + 3), ∼−17.0 (d, 1B, 1J(11B,1H) ≈
145 Hz, B5), −17.7 (d, 2B, J(11B,1H) = 150 Hz, B4 + 6). IR/Raman
1
(cm−1): 2065 cm−1 (ν(CC)). MALDI-MS m/z (isotopic abundance >
60) calcd for 7a ([C3H11B11Br]−): 244 (74%), 245 (100%), 246 (80%),
247 (97%), 248 (78%). Found: 243 (66%), 244 (88%), 245 (100%), 246
(92%), 247 (78%), 248 (62%). Anal. Calcd for C11H31B11BrN: C, 35.12;
H, 8.31; N, 3.72. Found: C, 33.09; H, 8.31; N, 3.74.
1
((CD3)2CO, δ ppm): 93.12 (q, 1C, J(13C,11B) = 101.9 Hz, B7−13C
13
CH), 82.19 (q, 1C, 2J(13C,11B) = 19.1 Hz, B7−C CH), 36.28
(s, 1C, Ccluster). 11B NMR ((CD3)2CO, δ ppm): 13.4 (s, 1B, B12), −13.8
2686
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
[Et4N][7,12-(HCC)2-closo-1-CB11H10] ([Et4N]8a). For prepara-
tion of the dialkynyl-functionalized anion a slightly modified synthesis
was applied. Me3SiCCMgBr (2.5 mL, 1.9 mmol) and
[PdCl2(PPh3)2] (16 mg, 0.023 mmol) were added in two equal
portions to Cs8 (200 mg, 0.38 mmol). The first one was added at the
beginning of the reaction and the second after 5 h. The reaction was
complete after microwave irradiation for further 4 h. The trimethylsilyl
groups were removed under basic aqueous conditions during workup.
Yield: 77 mg (0.24 mmol, 63%). Spectroscopic data and results of
elemental analysis have been reported earlier.33
to the procedure described for method A, except for stirring in THF at
40 °C for 1 h that was omitted, and thus, only a minor amount of the
allyl derivative 1n was isomerized to the vinyl species 1o. Yield 123 mg
(79%) of [Et4N][12-(CH2CHCH2)-closo-1-CB11H11] ([Et4N]1n,
84%) and [Et4N][12-(trans-CH3CHCH)-closo-1-CB11H11] ([Et4N]
1o, 16%).
12-Ph3P-closo-1-CB11H11 (2). Under an Ar atmosphere Cs[12-I-
closo-CB11H11] (Cs1) (100 mg, 0.25 mmol), [Pd(PPh3)4] (16.8 mg,
0.0145 mmol), PPh3 (130 mg, 0.5 mmol), and K2CO3 (35 mg,
0.25 mmol) were dissolved in dry THF (10 mL) in a glass finger
(70 mL) equipped with a valve with a PTFE stem (Young, London)
and fitted with a magnetic stirring bar. While stirring, the reaction
mixture was heated to 66 °C for 4 h by microwave irradiation. The
black reaction mixture was filtered, and all volatiles were removed
under reduced pressure. The solid residue was dissolved in a small
amount of chloroform, and pure 2 was precipitated by addition of
hexane. Yield: 89 mg (0.22 mmol, 88%). 1H{11B} NMR (toluene-d8, δ
ppm): 7.53−7.44 (m, 6H, Ph), 7.03−6.98 (m, 3H, Ph), 6.94−6.88 (m,
6H, Ph), 2.67 (s, 1H, CHcluster), 2.55 (s, 5H, BH7−11), 2.37 (d, 5H,
3J(31P,1H) = 5.3 Hz, BH2−6). 13C{1H} NMR (toluene-d8, δ ppm):
134.70 (d, 6C, 2J(31P,13C) = 9.0 Hz, Cortho), 132.52 (d, 3C, 4J(31P,13C) =
Preparation of [Et4N][12-(CH2CHCH2)-closo-1-CB11H11]/
[Et4N][12-(trans-CH3CHCH)-closo-1-CB11H11] ([Et4N]1n/[Et4N]
1o): Method A (Table 2, entry 12). Cs1 (200 mg, 0.50 mmol),
[PdCl2(PPh3)2] (28 mg, 0.040 mmol), and H2CCHCH2MgBr (3.5
mL, 3.5 mmol) were used in a slightly modified general procedure.
Catalyst and Grignard reagent were added in two portions: the
first one of [PdCl2(PPh3)2] (10 mg, 0.015 mmol) and H2C
CHCH2MgBr (1.0 mL, 1.0 mmol) at the start of the synthesis and the
second of [PdCl2(PPh3)2] (15 mg, 0.020 mmol) and H2C
CHCH2MgBr (2.5 mL, 2.5 mmol) after 24 h. The reaction was
complete after further 6 h. According to 11B{1H} NMR spectra the
mixture contains the allyl derivative [12-(CH2CHCH2)-closo-1-
CB11H11]− (1n) and approximately 12% of 2. The black reaction
mixture was poured into 50 mL of distilled water. The mixture was
stirred at 40 °C for 1 h, and then THF was removed at a rotary
evaporator. The clear aqueous phase was separated by filtration from
the black residue. For a further extraction, the black residue was
dissolved in 20 mL of dichloromethane and 30 mL of distilled water
were added. Dichloromethane was removed in a rotary evaporator, and
the aqueous phase was filtered. Product was precipitated as [Et4N]+
salt from the combined aqueous solutions by addition of [Et4N]Br
(500 mg, 2.4 mmol) dissolved in water (10 mL). Yield 120 mg (77%)
of [Et4N][12-(trans-CH3CHCH)-closo-1-CB11H11] ([Et4N]1o,
94%) and [Et4N][12-(CH2CHCH2)-closo-1-CB11H11] ([Et4N]1n,
3
2.8 Hz, Cpara), 128.84 (d, 6C, J(31P,13C) = 11.4 Hz, Cmeta), 123.47 (d,
3C, 1J(31P,13C) = 70.7 Hz, Cipso), 58.78 (s, 1C, Ccluster). 11B NMR
(toluene-d8, δ ppm): −9.6 (d, 1B, 1J(31P,11B) = 147 Hz, B12), −12.2 (d,
1
1
5B, J(11B,1H) = 144 Hz, B7−11), −14.1 (d, 5B, J(11B,1H) = 160,
B2−6). 31P{11B} NMR (toluene-d8, δ ppm): 2.3 (q, J(31P,11B) = 146.8
Hz). Anal. Calcd for C19H26B11P: C, 56.44; H, 6.48. Found: C, 56.63;
H, 6.42.
1
ASSOCIATED CONTENT
* Supporting Information
This material is available free of charge via the Internet at
http://pubs.acs.org.
■
S
1
6%). Spectroscopic data of the anion 1n. H{11B} NMR ((CD3)2CO,
δ ppm): 5.77 (ddt, 1H, 3J(1H,1H)trans = 17.0 Hz, 3J(1H,1H)cis = 9.9 Hz,
3J(1H,1H) = 7.7 Hz, B12−CH2−C1HCH2), 4.50 (dm, 1H,
3J(1H,1H)trans = 17.0 Hz, B12−CH2−CHC(H1Htrans)), 4.44 (dm, 1H,
3J(1H,1H)cis = 9.9 Hz, B12−CH2−CHC(H1Hcis)), 2.08 (sextet, 1H,
3J(1H,1H) = 3.1 Hz, CHcluster), 1.61 (s, 5H, BH), 1.56 (s, 5H, BH), 1.44
(m, 2H, B12−CH2). 13C{1H} NMR ((CD3)2CO, δ ppm): 145.16 (s, 1C,
AUTHOR INFORMATION
Corresponding Author
*E-mail: maik.finze@uni-wuerzburg.de.
■
Notes
The authors declare no competing financial interest.
13
B12−CH2−13CHCH2), 108.36 (s, 1C, B12−CH2−CH CH2),
1
45.88 (s, 1C, Ccluster), 26.16 (q, 1C, J(13C,11B) = 59.2 Hz, B12−CH2−
ACKNOWLEDGMENTS
■
CHCH2). 11B NMR ((CD3)2CO, δ ppm): 2.3 (s, 1B, B12), −12.5 (d,
This work was supported by the Fonds der Chemischen
Industrie (FCI). The authors thank Professor W. Frank for
generous support and Mrs. E. Hammes, Mr. P. Roloff, as well as
1
1
5B, J(11B,1H) = 135 Hz, B7−11), −16.6 (d, 5B, J(11B,1H) = 150 Hz,
B2−6). IR/Raman (cm−1): 1628 cm−1 (ν(CC)). Spectroscopic data of
the anion 1o. 1H{11B} NMR ((CD3)2CO, δ ppm): 5.48 (d, 1H,
3J(1H,1H) = 16.9 Hz, B12−C1HCH−CH3), 5.40 (dq, 1H, 3J(1H,1H) =
Dr. P. Tommes (all Universitat Dusseldorf) and Michael
̈
̈
16.9 Hz, J(1H,1H) = 5.6 Hz, B12−CHC1H−CH3), 1.51 (d, 3H,
3
Hailmann (Universitat Wurzburg) for technical support and
̈
̈
3J(1H,1H) = 5.6 Hz, CH3), 1.60 (s, 10H, BH2−11), 2.09 (s, 1H,
CHcluster). 13C{1H} NMR ((CD3)2CO, δ ppm): 138.96 (q, 1C,
1J(13C,11B) = 75.5 Hz, B12−13CHCH−CH3), 129.37 (s, 1C, B12−
helpful discussions. Computational support and infrastructure
was provided by the “Zentrum fur Informations- und
Medientechnologie” (ZIM) at the Heinrich-Heine-Universitat
̈
̈
CH CH−CH3), 46.22 (s, 1C, Ccluster), 21.45 (s, 1C, CH3). 11B NMR
13
Dusseldorf.
̈
((CD3)2CO, δ ppm): 0.9 (s, 1B, B12), −12.7 (d, 5B, J(11B,1H) = 134
1
Hz, B7−11), −16.8 (d, 5B, J(11B,1H) = 149 Hz, B2−6). IR/Raman
1
REFERENCES
(cm−1): 1634 cm−1 (ν(CC)). Identical data for [Et4N]1o and [Et4N]
1n. MALDI-MS m/z (isotopic abundance > 60) calcd for 1o and 1n
([C4H16B11]−): 182 (75%), 183 (100%), 184 (80%). Found: 182 (80%),
183 (100%), 184 (84%). Anal. Calcd for C12H36B11N: C, 45.99; H, 11.58;
N, 4.47. Found: C, 45.16; H, 11.51; N, 4.23.
■
(1) Korbe, S.; Schreiber, P. J.; Michl, J. Chem. Rev. 2006, 106, 5208−
̈
5249.
(2) Ivanov, S. V.; Rockwell, J. J.; Polyakov, O. G.; Gaudinski, C. M.;
Anderson, O. P.; Solntsev, K. A.; Strauss, S. H. J. Am. Chem. Soc. 1998,
120, 4224−4225.
Preparation of [Et4N][12-(CH2CHCH2)-closo-1-CB11H11]/
[Et4N][12-(trans-CH3CHCH)-closo-1-CB11H11] ([Et4N]1n/[Et4N]
1o): Method B (Table 2, entry 13). Synthesis was performed similar
to method A described for [Et4N]1n and [Et4N]1o starting with Cs1
(200 mg, 0.50 mmol). However, the amount of [PdCl2(PPh3)2]
(42 mg, 0.060 mmol) and H2CCHCH2MgBr (3.0 mL, 3.0 mmol)
was slightly different and CuI (10 mg, 0.050 mmol) was added. The
reagents were added in three equal portions: the first at the beginning
of the reaction, the second after 50 min, and the third after further
50 min of microwave irradiation. Workup was performed analogously
(3) Reed, C. A. Acc. Chem. Res. 2010, 43, 121−128.
(4) Douvris, C.; Stoyanov, E. S.; Tham, F. S.; Reed, C. A. Chem.
Commun. 2007, 1145−1147.
(5) Kuppers, T.; Bernhardt, E.; Willner, H. Angew. Chem. 2007, 119,
̈
6462−6465; Angew. Chem., Int. Ed. Engl. 2007, 46, 6346−6349.
(6) Fete, M. G.; Havlas, Z.; Michl, J. J. Am. Chem. Soc. 2011, 133,
4123−4131.
(7) Volkis, V.; Mei, H.; Shoemaker, R. K.; Michl, J. J. Am. Chem. Soc.
2011, 131, 3132−3133.
2687
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688

Inorganic Chemistry
Article
(8) Douvris, C.; Ozerov, O. V. Science 2008, 321, 1188−1190.
(9) Vyakaranam, K.; Barbour, J. B.; Michl, J. J. Am. Chem. Soc. 2006,
128, 5610−5611.
(44) Franken, A.; Jelínek, T.; Taylor, R. G.; Ormsby, D. L.; Kilner,
C. A.; Clegg, W.; Kennedy, J. D. Dalton Trans. 2006, 5753−5769.
(45) Dunks, G. B.; Barker, K.; Hedaya, E.; Hefner, C.;
Palmerordonez, K.; Remec, P. Inorg. Chem. 1981, 20, 1692−1697.
(46) Franken, A.; King, B. T.; Rudolph, J.; Rao, P.; Noll, B. C.; Michl,
J. Collect. Czech. Chem. Commun. 2001, 66, 1238−1249.
(10) Vyakaranam, K.; Korbe, S.; Michl, J. J. Am. Chem. Soc. 2006,
̈
128, 5680−5686.
(11) Larsen, A. S.; Holbrey, J. D.; Tham, F. S.; Reed, C. A. J. Am.
Chem. Soc. 2000, 122, 7264−7272.
(47) Sheldrick, G. M. SHELXS-97, Program for Crystal Structure
Solution; Universitat Gottingen: Gottingen, Germany, 1997.
̈
̈
̈
(12) Zhu, Y. H.; Ching, C. B.; Carpenter, K.; Xu, R.; Selvaratnam, S.;
Hosmane, N. S.; Maguire, J. A. Appl. Organomet. Chem. 2003, 17,
346−350.
(48) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112−122.
(49) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; Universitat Gottingen: Gottingen, Germany, 1997.
̈
̈
̈
(13) Cunha-Silva, L.; Ahmad, R.; Carr, M. J.; Franken, A.; Kennedy,
J. D.; Hardie, M. J. Cryst. Growth Des. 2007, 7, 658−667.
(14) Himmelspach, A.; Finze, M.; Raub, S. Angew. Chem. 2011, 123,
2676−2679; Angew. Chem., Int. Ed. Engl. 2011, 50, 2628−2631.
(50) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837−838.
(51) Brandenburg, K. Diamond 3.2g; Crystal Impact GbR: Bonn,
Germany, 1999−2011.
(52) Kohn, W.; Sham, L. J. Phys. Rev. A 1965, 140, 1133−1138.
(53) Becke, A. D. Phys. Rev. A 1988, 38, 3098−3100.
(54) Becke, A. D. J. Chem. Phys. 1993, 98, 5648−5652.
̌
̌ ̌ ́
k, J.; Hermanek, S.; Stíbr, B. Collect. Czech.
(15) Jelínek, T.; Plese
Chem. Commun. 1986, 51, 819−829.
(16) Sprenger, J. A. P.; Finze, M.; Schaack, B. B. Dalton Trans. 2010,
39, 2708−2716.
(55) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785−789.
(56) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.; Kudin, T. V. K. N.;
Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa,
J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene,
M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken, V.;
Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.;
Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.;
Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman,
J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.;
Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.;
Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.;
Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen,
W.; Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, Revision
D.01; Gaussian, Inc.: USA, 2004.
(17) Morris, J. H.; Henderson, K. W.; Ol’shevskaya, V. A. J. Chem.
Soc., Dalton Trans. 1998, 1951−1959.
(18) Gruner, B.; Janouse
̌
k, Z.; King, B. T.; Woodford, J. N.; Wang,
̈
C. H.; Vse
̌
teck
̌
a, V.; Michl, J. J. Am. Chem. Soc. 1999, 121, 3122−3126.
(19) Franken, A.; Kilner, C. A.; Thornton-Pett, M.; Kennedy, J. D.
J. Organomet. Chem. 2002, 657, 176−179.
(20) Bullen, N. J.; Franken, A.; Kilner, C. A.; Kennedy, J. D. Chem.
Commun. 2003, 1684−1685.
(21) Franken, A.; Kilner, C. A.; Thornton-Pett, M.; Kennedy, J. D.
Collect. Czech. Chem. Commun. 2002, 67, 869−912.
(22) Finze, M. Inorg. Chem. 2008, 47, 11857−11867.
(23) Finze, M. Eur. J. Inorg. Chem. 2009, 501−507.
(24) Mehta, V. P.; van der Eycken, E. V. Chem. Soc. Rev. 2011, 40,
4925−2936.
(25) Caddick, S.; Fitzmaurice, R. Tetrahedron 2009, 65, 3325−3355.
(26) Nilsson, P.; Olofsson, K.; Larhed, M. Top. Curr. Chem. 2006,
266, 103−144.
(27) Kappe, C. O. Angew. Chem. 2004, 116, 6408−6443; Angew.
Chem., Int. Ed. Engl. 2004, 43, 6250−6284.
(57) Rienstra-Kiracofe, J. C.; Tschumper, G. S.; Schaefer, H. F. III;
Nandi, S.; Ellison, G. B. Chem. Rev. 2002, 102, 231−282.
(28) Walla, P.; Kappe, C. O. Chem. Commun. 2004, 564−565.
(58) Hattig, C.; Weigend, F. J. Chem. Phys. 2000, 113, 5154−5161.
̈
̌
́ ̌
ek, M.; Stursa, J.; Pohl, R.; Michl, J. Inorg. Chem. 2010, 49,
(29) Valas
10255−10263.
(30) Valas k, M.; Stursa, J.; Pohl, R.; Michl, J. Inorg. Chem. 2010, 49,
(59) The corresponding literature for the basis sets can be found at
ftp://ftp.chemie.uni-karlsruhe.de/pub/basen. The corresponding liter-
ature for the basis sets can be found at ftp://ftp.chemie.uni-karlsruhe.
de/pub/basen.
̌
́ ̌
e
10247−10254.
(31) Green, A. E. C.; Causey, P. W.; Louie, A. S.; Armstrong, A. F.;
Harrington, L. E.; Valliant, J. F. Inorg. Chem. 2006, 45, 5727−5729.
(32) Peymann, T.; Knobler, C. B.; Hawthorne, M. F. Inorg. Chem.
1998, 37, 1544−1548.
(33) Himmelspach, A.; Finze, M. J. Organomet. Chem. 2010, 695,
1337−1345.
(34) Finze, M.; Reiss, G. J. Acta Crystallogr. 2009, E65, o1048.
(35) Momming, C. M.; Kehr, G.; Wibbeling, B.; Frohlich, R.;
̈
̈
Schirmer, B.; Grimme, S.; Erker, G. Angew. Chem. 2010, 122, 2564−
2467; Angew. Chem., Int. Ed. Engl. 2010, 49, 2414−2417.
(36) Bernard, R.; Cornu, D.; Luneau, D.; Naoufal, D.; Scharff, J.-P.;
Miele, P. J. Organomet. Chem. 2005, 690, 2745−2749.
(37) Finster, D. C.; Hutton, W. C.; Grimes, R. N. J. Am. Chem. Soc.
1980, 102, 400−401.
(38) Colquhoun, I. J.; McFarlane, W. J. Chem. Soc., Dalton Trans.
1981, 2014−2016.
(39) Venable, T. L.; Hutton, W. C.; Grimes, R. N. J. Am. Chem. Soc.
1982, 104, 4716−4717.
(40) Venable, T. L.; Hutton, W. C.; Grimes, R. N. J. Am. Chem. Soc.
1984, 106, 29−37.
(41) Jelínek, T.; Kilner, C. A.; Thornton-Pett, M.; Kennedy, J. D.
Chem. Commun. 2001, 1790−1791.
(42) Jelínek, T.; Thornton-Pett, M.; Kennedy, J. D. Collect. Czech.
Chem. Commun. 2002, 67, 1035−1050.
(43) Franken, A.; Kilner, C. A.; Thornton-Pett, M.; Kennedy, J. D.
J. Organomet. Chem. 2002, 657, 180−186.
2688
dx.doi.org/10.1021/ic202638k | Inorg. Chem. 2012, 51, 2679−2688