Reactivity studies on 2,3,4,5-tetraethyl-1,6-diiodo-2,3,4,5-tetracarba-nido hexaborane(6): Synthesis and structures of new C4B2 nido-carborane derivatives

Article abstract of DOI:10.1002/ejic.200300938

The reactivity of the title compound 2,3,4,5-tetraethyl-1,6-diiodo-2,3,4,5- tetracarba-nido-hexaborane(6) (1) towards a variety of nucleophiles is reported. When 1 is treated with RC₂Li (R = Ph, tBu, SiMe₃, p-tolyl) and Ph₂

Full text of DOI:10.1002/ejic.200300938

FULL PAPER
Reactivity Studies on 2,3,4,5-Tetraethyl-1,6-diiodo-2,3,4,5-tetracarba-nido-
hexaborane(6): Synthesis and Structures of New C4B2 nido-Carborane
Derivatives
Yong Nie,[a] Hans Pritzkow,[a] and Walter Siebert*[a]
Dedicated to Professor Manfred T. Reetz on the occasion of his 60th birthday
Keywords: Boron / Carboranes / Nucleophilic substitution / Iron / Cobalt
The reactivity of the title compound 2,3,4,5-tetraethyl-1,6-di- 1,6-disubstituted species 6b and 7b are also detected. The
iodo-2,3,4,5-tetracarba-nido-hexaborane(6) (1) towards
a
substitution at the apical B−I group in 2a with an alkynyl
variety of nucleophiles is reported. When 1 is treated with group is effected by a Pd0-catalyzed Negishi-type cross-
RC2Li (R = Ph, tBu, SiMe3, p-tolyl) and Ph2PLi, the corres- coupling reaction to give compound 8. The reaction of 1 and
ponding new C4B2 nido-carborane derivatives 2a−d and 3, monolithio-o-carborane affords the C4B2−C2B10 carborane
respectively, are obtained by selective substitution at the 10, while the reaction of 2a and Co2(CO)8 furnishes the
basal B−I group, whereas the apical B−I bond remains inert. double cluster 9 (C4B2−C2Co2). In both 9 and 10 two different
The reaction of 1 with K[(η5-C5H5)Fe(CO)2] affords the novel types of clusters are directly connected by a B−C bond. Com-
species 4, which contains a CpFe(CO)2 fragment σ-bonded to pound 1 reacts with ClZnC6H4C6H4ZnCl in the presence of
the basal boron atom of the C4B2 cluster. Attempts to isolate 4 the catalyst Pd(PPh3)4 to give 11, in which two C4B2 clusters
by chromatography on silica gel led to cleavage of the Fe−B are linked by a C6H4C6H4 unit. The constitutions of the prod-
bond and formation of compound 5, containing a basal BH ucts follow from spectroscopic data, and X-ray diffraction
vertex, which can be separately prepared by the reaction of analyses for 2a, 2d, 4, 8, 9, and 10.
1 and LiBEt3H. In the reactions of 1 with PhLi and Me3SnLi,
respectively, 6a and 7a are formed as the predominant B6- ( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
substituted carborane products. In addition, trace amounts of Germany, 2004)
formed.[3b] Nucleophiles were found to replace the basal
Introduction
B6-bromo atom to give the corresponding carboranes with
organyl,[3c]stannyl,[3d] diphenylphosphanyl[3e] as well as the
Although peralkylated 2,3,4,5-tetracarba-nido-hexabor-
[3f]
N-bonded (µ-NS)Fe2(CO)6
group. In the 1,6-dibromo
anes(6)[1] are more stable than the parent compound
C4B2H6,[2] and are readily available by a variety of methods,
their reactivity has only recently been studied.[3,4] To investi-
gate substitution reactions in C4B2 nido-carboranes, func-
tional groups at the boron atom(s) other than alkyl groups
are needed. Wrackmeyer et al. were able to obtain 1,6-di-
bromo-2,3,4,5-tetracarba-nido-hexaboranes(6)[3a] by treat-
case, substitution with the N-bonded (µ-NS)Fe2(CO)6 clus-
ter took place at the basal BϪBr bond, an excess of the
nucleophile did not induce additional substitution at the
1-position.[3f]
Berndt et al.[4] have reported that the reduction of nido-
(Me3SiC)2(CH)2(BtBu)2 with Li in tetrahydrofuran affords
a novel 1,3-diborabenzene anion, which could in turn be
oxidized to give the starting carborane in refluxing 1,2-di-
bromoethane. As part of reactivity studies, we have re-
ported transition metal derivatives of a benzo-C4B2 nido-
carborane compound[5a] with metal complex fragments co-
ordinated to the benzene ring.[5b] Very recently we have de-
veloped a convenient one-pot synthesis of 2,3,4,5-tetra-
alkyl-1,6-diiodo-2,3,4,5-tetracarba-nido-hexaborane(6) de-
ing
1,4,6,9-tetraalkyl-3,8-diethyl-2,7-bis(diethylboryl)-5-
stannaspiro[4.4]nona-1,3,6,8-tetraenes with BBr3. They also
studied the reaction between peralkylated 2,3,4,5-tetra-
carba-nido-hexaboranes(6) and an excess of BBr3, whereby
the corresponding B6-bromo-substituted carboranes were
rivatives,[6] involving disubstituted alkynes, BI3 and NaK2.8
.
[a]
Anorganisch-Chemisches Institut der Universität Heidelberg
In this paper, we report the reactivity of the title compound
1 towards a variety of nucleophiles, and characterization of
the resulting new carboranes.
Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
Fax: (internat.) ϩ 49-6221-545-609
E-mail: walter.siebert@urz.uni-heidelberg.de
Eur. J. Inorg. Chem. 2004, 2425Ϫ2433
DOI: 10.1002/ejic.200300938
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Y. Nie, H. Pritzkow, W. Siebert
FULL PAPER
tals of 4, along with an unknown paramagnetic impurity,
which makes the NMR spectra not so satisfactory.
The initial isolation of 4 by column chromatography on
silica gel led to cleavage of the FeϪB bond to give 5 and
paramagnetic impurities. The designed synthesis of 5 is
achieved by the separate reaction of 1 with LiBEt3H. No
redox reaction between 1 and (MeS)2 takes place, indicating
the BϪI bonds in 1 are dissimilar to the classical BϪI bond
of sp2-hybridized boron atoms, which reacts to give the cor-
responding BϪSMe products.[8]
Results and Discussion
Regiospecific Substitution at the Basal Boron Atom
Nucleophilic substitution reactions of 1 with RC2Li (R ϭ
Ph, tBu, SiMe3, p-tolyl) proceed smoothly, and the corre-
sponding basal-boron-substituted carborane derivatives
2aϪd were produced in high yields (Scheme 1). The nido-
C4B2 framework is retained, as little differences have been
found in the 1H and 13C NMR spectra when compared with
that of 1. In the 11B NMR spectra, the basal boron atoms
give rise to signals at δ ϭ 9.8Ϫ10.9 ppm, which are only
slightly shifted downfield from that of 1 (δ ϭ 5.5 ppm),
while the shifts of the signals for the apical boron atoms
are the same as that for 1 (δ ϭ Ϫ52.5 ppm).
Reactions Involving Substitution at Both Boron Atoms
In the reactions of 1 with more than 2 equiv. of PhLi
and Me3SnLi, respectively (Scheme 2), the B6-substituted
products 6a and 7a are formed, together with trace amounts
of the disubstituted species 6b and 7b, as detected by mass
spectrometry. For 6a and 7a, the 11B NMR signals of the
basal boron atoms are shifted downfield to δ ϭ 17.9 and
16.1 ppm, respectively, while the signals of the apical boron
atoms are unchanged.
Scheme 1
Scheme 2
X-ray structure analyses of 2a and 2d confirm the spec-
In most of the cases the apical BϪI bonds are found to
troscopic results. In agreement with Herberhold, Wrack- be inert, although its substitution by an alkynyl group has
meyer et al.,[3f] an excess of lithium acetylide did not effect been realized by a Pd0-catalyzed Negishi-type cross-coup-
additional substitution at the apical boron atoms. Similar ling reaction of 2a and Me3SiC2ZnCl in THF (Scheme 3).
results are observed in the reactions of 1 with Ph2PLi and Heating of the reaction mixture for 10 d leads to yellow 8.
K[(η5-C5H5)Fe(CO)2] to give 3 and 4, respectively, with re- Interestingly, the 11B NMR signal of the substituted apical
giospecific substitution at the basal position. In the 11B boron atom is only slightly shifted downfield to δ ϭ
NMR spectrum of 3, the signal of the basal boron atom is Ϫ50.7 ppm. Its structure was established by an X-ray dif-
shifted downfield by about 9 ppm, while the apical boron fraction analysis (see below). The mechanism of such Pd-
atom is unaffected. In the case of 4, the basal boron atom catalyzed coupling reactions involving BϪI bonds[9a] is ex-
of the C4B2 nido-cluster is significantly deshielded (δ ϭ pected to be similar to that of carbonϪcarbon cross coup-
28.6 ppm), and the signal of the apical boron is slightly ling, however the very first step in the catalytic cycle — the
shifted to δ ϭ Ϫ49.6 ppm. This reveals that the CpFe(CO)2 oxidative addition of the BϪI bond leading to a BϪPdϪI
fragment is directly bonded to the basal boron atom by an species — has not yet been verified. Stirring of a mixture
FeϪB σ-bond, which is confirmed by an X-ray diffraction of 2a and Pd(PPh3)4 in THF leads to a brown solution,
study (vide infra). Thus, 4 is the first transition metal de- whose 31P NMR spectrum shows a signal at δ ϭ 22.4 ppm,
rivative of the C4B2 nido-carborane with direct which is in the expected region {[PdIPh(PPh3)2]: δ ϭ
metalϪboron bonding. A few iron derivatives[7] with other 22.3 ppm}.[9b] Its 11B NMR spectrum shows a signal at δ ϭ
carborane or polyborane frameworks of this type have been Ϫ36 ppm, which might be due to the formation of the (σ-
reported with FeϪB or FeϪC bonding. Cooling of the solu- carboranyl)palladium iodide complex. Shore et al.[10] have
tion of the crude product in hexane resulted in yellow crys- studied the reaction of Pd(PPh3)4 with the iodoborane clus-
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Synthesis and Structures of New C4B2-nido-carborane Derivatives
FULL PAPER
ter 9-I-1,7-(SMe2)2B12H9 and they observed similar results 1 with ClZnC6H4C6H4ZnCl in the presence of a catalytic
(δ31 ϭ 24.2/24.0 ppm).
amount of Pd(PPh3)4. It should be noted that the reaction
leading to 11 is performed in toluene because the basal BϪI
bond in 1 is sensitive to THF, resulting first in a yellow and
then a deep-green solution. This is significantly different to
the bromo derivatives of nido-C4B2, which have been stud-
ied in THF solution.[3dϪ3f] In compounds 10 and 11 the
11B NMR signals of the basal boron atoms are shifted
downfield to δ ϭ 13.9 and 22.0 ppm, respectively, while the
apical boron atom is essentially unaffected (δ ϭ Ϫ53.4 ppm
for 10 and δ ϭ Ϫ52.4 ppm for 11). The MS spectra exhibit
the respective molecular ion peaks with the correct iso-
topic patterns.
P
The reaction of 1 with LiC6H4C6H4Li did not yield the
expected product 11, instead the oxygen-bridged species 12
was detected, formed by the hydrolysis of 1. In the Et3N/
H2O reaction (Scheme 5), the formed by-product am-
monium salt [Et3NH]I, was identified by FAB-MS. Com-
pound 12 was characterized by 11B NMR spectroscopy
(δ ϭ 22.1 and Ϫ51.9 ppm) and HR-MS which exhibits the
molecular ion peak with the correct isotopic pattern.
Scheme 3
Cluster Linkages
Nucleophilic substitution of B-functionalized C4B2 nido-
carboranes by an anionic cluster (µ-NS)Fe2(CO)6
Ϫ [3f]
has
been shown to be an effective way to linked clusters. The
reaction of 2a with Co2(CO)8, shown in Scheme 3, leads to
the deep-brown product 9, in which the nido-C4B2 and the
C2Co2 tetrahedrane cluster are directly joined by a BϪC
bond at the basal position. In the 11B NMR spectrum, the
signal for the basal boron atom is shifted downfield by
6.5 ppm relative to that of 2a, while the signal for the apical
boron atom is only slightly shifted downfield by about
1.5 ppm. The molecular structure of 9 was confirmed by an
X-ray diffraction analysis (see below). There are only a few
acetyleneϪCo2(CO)6 complexes with boron groups at-
tached to the acetylene unit,[11] and two[11b,11c] structurally
characterized examples carry BϪcat groups (cat ϭ cat-
echol). The C4B2ϪC2B10 linked cluster 10 (Scheme 4) is
produced by the reaction of 1 with monolithio-o-carborane,
in which the C4B2 cluster is directly connected to the icosa-
hedral o-carborane by a B6ϪC bond, as confirmed by X-
ray diffraction analysis.
Scheme 5
X-ray Structure Analyses of 2a, 2d, 4, 8, 9 and 10
The molecular structures of 2a, 4, 8, 9 and 10 are shown
in Figures 1, 2, 3, 4, and 5, respectively. As the structure of
2d (at room temperature) is very similar to that of 2a, it will
not be shown here. In the structures, the C4B2 nido-carbor-
ane frameworks are essentially the same as that of the start-
Figure 1. Molecular structure of 2a; hydrogen atoms omitted for
clarity; thermal ellipsoids are shown at 40% probability; selected
˚
bond lengths [A] and angles [°]: I(1)ϪB(1) 2.139(2), B(1)ϪC(1)
Scheme 4
1.714(3), B(1)ϪC(2) 1.722(3), B(1)ϪC(3) 1.714(3), B(1)ϪC(4)
1.706(3), B(1)ϪB(2) 1.825(3), B(2)ϪC(1) 1.537(3), B(2)ϪC(4)
1.532(3), C(1)ϪC(2) 1.453(3), C(2)ϪC(3) 1.446(2), C(3)ϪC(4)
1.459(3), B(2)ϪC(5) 1.529(3), C(5)ϪC(6) 1.211(3), C(6)ϪC(7)
1.435(3); B(2)ϪB(1)ϪI(1) 143.3(1), C(5)ϪB(2)ϪB(1) 131.2(2),
Compound 11 with two C4B2 clusters connected by a
C6H4C6H4 unit (Scheme 4) is obtained from the reaction of C(6)ϪC(5)ϪB(2) 177.0(2), C(5)ϪC(6)ϪC(7) 178.3(2)
Eur. J. Inorg. Chem. 2004, 2425Ϫ2433
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Y. Nie, H. Pritzkow, W. Siebert
FULL PAPER
Figure 4. Molecular structure of 9; hydrogen atoms omitted for
clarity; thermal ellipsoids are shown at 40% probability; selected
˚
bond lengths [A] and angles [°]: I(1)ϪB(1) 2.121(2), B(1)ϪC(1)
1.712(3), B(1)ϪC(2) 1.712(3), B(1)ϪC(3) 1.718(3), B(1)ϪC(4)
1.705(3), B(1)ϪB(2) 1.826(3), B(2)ϪC(1) 1.537(3), B(2)ϪC(4)
1.537(3), C(1)ϪC(2) 1.458(3), C(2)ϪC(3) 1.443(3), C(3)ϪC(4)
Figure 2. Molecular structure of 4; hydrogen atoms omitted for
clarity; thermal ellipsoids are shown at 40% probability; selected
˚
bond lengths [A] and angles [°]: I(1)ϪB(1) 2.135(2), B(1)ϪC(1)
1.456(3),
B(2)ϪC(13)
1.554(3),
C(13)ϪC(14)
1.348(3),
1.692(2), B(1)ϪC(2) 1.711(2), B(1)ϪC(3) 1.709(2), B(1)ϪC(4)
1.689(3), B(1)ϪB(2) 1.841(3), B(2)ϪC(1) 1.547(2), B(2)ϪC(4)
1.547(2), C(1)ϪC(2) 1.460(2), C(2)ϪC(3) 1.431(2), C(3)ϪC(4)
1.468(2), Fe(1)ϪB(2) 2.069(2), Fe(1)ϪC(19) 1.739(2), Fe(1)ϪC(18)
1.742(2), Fe(1)ϪCCp 2.094Ϫ2.116(2), O(1)ϪC(18) 1.150(2),
C(14)ϪC(15) 1.465(3), Co(1)ϪCo(2) 2.483(4), Co(1)ϪC(13)
1.999(2),
Co(1)ϪC(14)
1.952(2),
Co(2)ϪC(13)
1.990(2),
140.7(2),
141.1(2),
Co(2)ϪC(14)
1.976(2);
130.5(2),
B(2)ϪB(1)ϪI(1)
C(13)ϪB(2)ϪB(1)
C(13)ϪC(14)ϪC(15) 140.1(2)
C(14)ϪC(13)ϪB(2)
O(2)ϪC(19)
B(1)ϪB(2)ϪFe(1) 133.48(11), C(19)ϪFe(1)ϪC(18) 92.59(10),
C(19)ϪFe(1)ϪB(2) 86.26(8), C(18)ϪFe(1)ϪB(2) 85.03(8),
O(1)ϪC(18)ϪFe(1) 178.7(2), O(2)ϪC(19)ϪFe(1) 178.6(2)
1.151(2);
B(2)ϪB(1)ϪI(1)
142.91(11),
Figure 5. Molecular structure of 10; hydrogen atoms omitted for
clarity; thermal ellipsoids are shown at 40% probability; selected
˚
bond lengths [A] and angles [°]: I(1)ϪB(12) 2.125(2), B(12)ϪC(3)
1.708(2), B(12)ϪC(4) 1.731(2), B(12)ϪC(5) 1.731(2), B(12)ϪC(6)
1.710(2), B(11)ϪB(12) 1.817(2), B(11)ϪC(3) 1.543(2), B(11)ϪC(6)
1.541(2),
B(11)ϪC(1)
1.595(2),
C(1)ϪC(2)
1.687(2),
B(11)ϪB(12)ϪI(1) 141.46(10), C(1)ϪB(11)ϪB(12) 132.04(12)
B2ϪB1ϪX angle being 143.3(3)°, 141.3(3)°, 141.9(1)°,
142.5(1)°, 140.7(2)° and 141.5(1)°, respectively (in 1 the cor-
responding angle is 140.06°).
Figure 3. Molecular structure of 8; hydrogen atoms omitted for
clarity; thermal ellipsoids are shown at 40% probability; selected
˚
bond lengths [A] and angles [°]: B(1)ϪC(1) 1.723(2), B(1)ϪC(2)
In 4, a CpFe(CO)2 fragment is directly σ-bonded to the
1.735(2), B(1)ϪC(3) 1.734(2), B(1)ϪC(4) 1.731(2), B(1)ϪB(2)
1.833(2), B(2)ϪC(1) 1.532(2), B(2)ϪC(4) 1.532(2), C(1)ϪC(2)
1.455(2), C(2)ϪC(3) 1.440(2), C(3)ϪC(4) 1.452(2), B(2)ϪC(13)
˚
basal boron atom, the FeϪB bond length is 2.069 A, which
is significantly longer than the corresponding values for
[13a,13b]
˚
1.536(2),
C(13)ϪC(14)
1.207(2),
C(14)ϪC(15)
1.438(2),
ironϪboryl complexes, [1.959(6)Ϫ2.034(3) A,
B(1)ϪC(21) 1.522(2), C(21)ϪC(22) 1.205(2); C(21)ϪB(1)ϪB(2)
142.49(10), C(13)ϪB(2)ϪB(1) 132.30(10), C(14)ϪC(13)ϪB(2)
175.39(13), C(13)ϪC(14)ϪC(15) 178.79(13), C(22)ϪC(21)ϪB(1)
177.62(12) C(21)ϪC(22)ϪSi(1) 175.45(12)
1.964(8)Ϫ2.027(5) A[13c,13d]] and ironϪborylene complexes
˚
[2.010(3) A[13e]], but in the range of the reported values for
˚
ferracarboranes (1.968Ϫ2.161 A[13f]). This long FeϪB dis-
˚
tance is also consistent with the easy decomposition of 4
ing carborane 1.[6] The BϪI bond lengths in 2a (2.139 A), with the cleavage of the FeϪB bond on silica gel. The iron
˚
˚
˚
˚
˚
2d (2.119 A), 4 (2.135 A), 9 (2.121 A) and 10 (2.125 A) are center achieves an 18-electron configuration through coor-
very similar to the corresponding value (2.126 A) in 1 de- dination to two CO ligands (2e donor), the cyclopen-
˚
spite the B6-substitution. In the alkynyl-substituted com- tadienyl group (5e donor), and the FeϪB interaction (1e
pounds 2a, 2d and 8, the BϪCϪC moieties are almost lin- donor).
ear, and the corresponding BϪCϪC bond angles are 177.0°
In the structure of 9 (Figure 4), the almost linear BϪCϵ
for 2a, 173.2° for 2d, and 177.6° (apical)/175.4° (basal) for CϪCmoiety in 2a has been altered by the complexation of
˚
8. The BϪC and CϵC bond lengths in 2a (1.529, 1.211 A), the Co2(CO)6 fragment, with the angles decreasing to
˚
˚
2d (1.530, 1.197 A), and 8 (1.522, 1.205 A) are similar to 141.07° (B2ϪC13ϪC14) and 140.1° (C13ϪC14ϪC15). The
each other, and are also in agreement with the reported val- Co1ϪCo2 and C13ϪC14 bond lengths of 2.483 and 1.348
ues for borylacetylenes.[11c,12] In 2a, 2d, 4, 8, 9 and 10, the A, respectively, are similar to the corresponding values in
˚
apical substituents are bent away from the Bbasal group, the similar complexes carrying BϪcat groups.[11b,11c]
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Synthesis and Structures of New C4B2-nido-carborane Derivatives
FULL PAPER
yellow filtrate, which was dried in vacuo to give 2a as a yellow
powder (746 mg, 88%), m.p. 74 °C. Crystals suitable for X-ray dif-
fraction analysis were grown from a toluene/hexane solution at Ϫ28
The structure of 10 (Figure 5) contains the small C4B2
nido-cluster connected to the large closo-o-carboranyl clus-
ter. Interestingly, in the asymmetric unit two cocrystallized
free o-carborane molecules have been found, and surpris-
ingly there is no significant intermolecular interaction
among the three molecules. The B11ϪC1 bond length of
3
°C. 1H NMR: δ ϭ 1.25 (t, JH,H ϭ 7.6 Hz, 6 H, CH3), 1.33 (t,
3JH,H ϭ 7.6 Hz, 6 H, CH3), 2.0 (m), 2.38 (m) (8 H, CH2), 7.27Ϫ7.48
(m, Ph) ppm. 11B NMR: δ ϭ 10.3 (s, Bbasal), Ϫ52.6 (s, Bapical) ppm.
13C NMR: δ ϭ 13.4, 14.3 (CH3), 18.4, 19.8 (CH2), 104.4 (br., B-
bound basal C atoms), 113.0 (skeletal C atoms non-adjacent to the
basal B atom), 124.6, 127.6, 128.1, 131.7 (Ph) ppm; signals of alky-
nyl C atoms not observed. EI-MS: m/z (%) ϭ 414 (100) [Mϩ], 287
˚
1.595 A is typical of a CϪB single bond. In the o-carbor-
˚
anyl fragment the C1ϪC2 bond length is 1.687 A, which is
[14]
˚
significantly longer than that in o-carborane [1.630(6) A].
The BϪB bond lengths [av. distance 1.776(2) A, ranging (14.6) [Mϩ Ϫ I]. HR-MS (EI): m/z ϭ 414.1224 [Mϩ]; calcd. for
˚
12
1H2511B2127I 414.1187 (∆m ϭ 3.7 mmu).
˚
C
20
from 1.744(2) to 1.793(2) A] and the CϪB bond lengths [av.
˚
˚
distance 1.720(2) A, ranging from 1.703(2) to 1.731(2) A]
are close to the expected values.
6-(tert-Butylethynyl)-2,3,4,5-tetraethyl-1-iodo-2,3,4,5-tetracarba-
nido-hexaborane(6) (2b): Prepared in a similar manner to 2a from
tBuCϭCLi (750 mg, 8.5 mmol) and 1 (528 mg, 1.2 mmol) in hex-
ane (50 mL). Compound 2b (450 mg, 95%) was obtained as a yel-
1
Conclusion
low oil. H NMR: δ ϭ 1.2 (br., 6 H, CH3), 1.25 (br., 6 H, CH3),
1.25 (s, 9 H, tBu-H), 1.91 (m), 2.28 (m) (8 H, CH2) ppm. 11B NMR:
δ ϭ 10.8 (s, Bbasal), Ϫ52.6 (s, Bapical) ppm. 13C NMR: δ ϭ 13.4, 14.0
(CH3), 18.3, 19.6 (CH2), 30.8 [C(CH3)3], 31.2 [C(CH3)3], signals of
B-bound basal C atoms not observed, 112.3 (skeletal C atoms non-
adjacent to the basal B atom) ppm; signals of alkynyl C atoms not
The reactivity of compound 1 towards various nucleo-
philes has been investigated. In most of the cases, the substi-
tution with hydride, alkynyl, diphenylphosphanyl, trimeth-
ylstannyl, CpFe(CO)2, and even the bulky o-carboranyl
group, takes place regiospecifically at the basal boron atom
of the nido-C4B2 frameworks, while the ‘‘inert’’ apical B؊I
bond can be substituted by a Pd0-catalyzed Negishi-type
cross-coupling reaction, as demonstrated in the synthesis of
compound 8. A new strategy for cluster linkages has been
developed, and compounds with different types of cluster
linkages have been prepared, either by direct B؊C bonding
observed. EI-MS: m/z (%) ϭ 394 (100) [Mϩ], 267 (10.8) [Mϩ Ϫ I].
12
HR-MS (EI): m/z ϭ 394.1517 [Mϩ]; calcd. for
394.1500 (∆m ϭ 1.7 mmu).
C
18
1H2911B2127I
2,3,4,5-Tetraethyl-1-iodo-6-(trimethylsilylethynyl)-2,3,4,5-tetra-
carba-nido-hexaborane(6) (2c): Prepared in a similar manner to 2a
from Me3SiCϭCH (310 mg, 3.16 mmol), nBuLi (2.5  in hexanes,
3 mmol) and 1 (634 mg, 1.44 mmol) in hexane (50 mL). Compound
1
2c (536 mg, 91%) was obtained as a yellow oil. H NMR: δ ϭ 0.18
(C4B2ϪC2B10 and C4B2ϪC2Co2), or by
a
linking
3
3
(s, SiMe3), 1.21 (t, JH,H ϭ 7.6 Hz, 6 H, CH3), 1.26 (t, JH,H
ϭ
C6H4C6H4 unit, at the basal boron atom of the nido-C4B2
skeletons. The reactivity of the basal BϪI bond of 1 is
further shown by its sensitivity to THF as solvent and by
the formation of the oxygen-bridged species 12.
7.6 Hz, 6 H, CH3), 1.94 (m), 2.29 (m) (8 H, CH2) ppm. 11B NMR:
δ ϭ 9.8 (s, Bbasal), Ϫ52.8 (s, Bapical) ppm. 13C NMR: δ ϭ 0.18
(SiMe3), 13.3, 14.1 (CH3), 18.3, 19.7 (CH2), 105.2 (B-bound basal
C atoms), 112.8 (skeletal C atoms non-adjacent to the basal B
atom) ppm; signals of alkynyl C atoms not observed. 29Si NMR
(CDCl3, 39.7 MHz): δ ϭ Ϫ19.8 ppm. EI-MS: m/z (%) ϭ 410 (100)
[Mϩ], 283 (13.5) [Mϩ Ϫ I]. HR-MS (EI): m/z ϭ 410.1265 [Mϩ];
Experimental Section
12
calcd. for
C
17
1H2911B2127I 410.1269 (∆m ϭ Ϫ0.4 mmu).
General: All reactions and manipulations were performed in dry
glassware under argon or nitrogen using standard Schlenk tech-
niques. Solvents were dried, distilled, and saturated with nitrogen.
NMR spectra were recorded with a Bruker DRX 200 spectrometer
(1H: 200.13 MHz, 11B: 64.21 MHz, 13C: 50.32 MHz) in CDCl3 as
the solvent. Et2O·BF3 was used as the external standard for 11B
NMR spectroscopy, and as internal references for 1H and 13C
NMR spectroscopy the signals of the deuterated solvents were used
and calculated relative to TMS. MS: ZAB-2F VH Micromass CTD
spectrometer, and a JEOL MS Station JMS 700 spectrometer both
using the EI or FAB ionization techniques. Melting points (uncor-
rected) were measured with a Büchi apparatus, using capillaries
which were filled under nitrogen and sealed. K[(η5-
C5H5)Fe(CO)2][15] and Me3SnLi[16] were prepared according to lit-
erature procedures.
2,3,4,5-Tetraethyl-1-iodo-6-(p-tolylethynyl)-2,3,4,5-tetracarba-nido-
hexaborane(6) (2d): Prepared in a similar manner to 2a from p-
tolylacetylene (431 mg, 3.72 mmol) and 1 (264 mg, 0.6 mmol) in
hexane (50 mL). Compound 2d (247 mg, 96%) was obtained as a
yellow solid, m.p. 81 °C. Crystals suitable for X-ray analysis were
1
grown from a toluene solution at Ϫ28 °C. H NMR: δ ϭ 1.24 (t,
3
3JH,H ϭ 7.6 Hz, 6 H, CH3), 1.31 (t, JH,H ϭ 7.6 Hz, 6 H, CH3),
1.97 (m), 2.29 (m) (8 H, CH2), 2.32 (s, 3 H, p-tolyl-CH3), 7.08 (d,
3JH,H ϭ 7.94 Hz, C6H4), 7.38 (d, 3JH,H ϭ 7.94 Hz, C6H4) ppm. 11
B
NMR: δ ϭ 10.9 (Bbasal), Ϫ52.6 (s, Bapical) ppm. 13C NMR: δ ϭ
13.3, 14.2 (CH3), 18.4, 19.7 (CH2), 21.4 (p-tolyl-CH3), signals of B-
bound basal C atoms not observed, 112.9 (skeletal C atoms non-
adjacent to the basal B atom), 121.6, 128.8, 131.6, 137.6 (C6H4)
ppm; signals of alkynyl C atoms not observed. EI-MS: m/z (%) ϭ
428 (100) [Mϩ], 301 (13.6) [Mϩ Ϫ I]. HR-MS (EI): m/z ϭ 428.1360
2,3,4,5-Tetraethyl-1-iodo-6-(phenylethynyl)-2,3,4,5-tetracarba-nido-
hexaborane(6) (2a): nBuLi (2.5  in hexanes, 2 mL) was added at
Ϫ50 °C to a solution of phenlyacetylene (507 mg, 5 mmol) in hex-
ane (30 mL), the mixture was stirred for 30 min, and then warmed
up to room temp. The resulting white suspension was cooled to
Ϫ60 °C, and added with a syringe to a solution of 1 (900 mg,
12
[Mϩ]; calcd. for
C
21
1H2711B2127I 428.1344 (∆m ϭ 1.6 mmu).
2,3,4,5-Tetraethyl-1-iodo-6-(diphenylphosphanyl)-2,3,4,5-tetracarba-
nido-hexaborane(6) (3): suspension of Ph2PLi (170 mg,
A
0.88 mmol, prepared in situ from HPPh2 and nBuLi in hexane) in
hexane (5 mL) was cooled to Ϫ60 °C and added to a solution of 1
2.05 mmol) in hexane (30 mL). The mixture was warmed to room (194 mg, 0.44 mmol) in hexane (10 mL). The mixture was allowed
temperature and stirred for 2 d. Filtration (G4 frit) gave a light- to warm to room temp., stirred overnight and filtered. The yellow
Eur. J. Inorg. Chem. 2004, 2425Ϫ2433
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2429

Y. Nie, H. Pritzkow, W. Siebert
FULL PAPER
filtrate was dried in vacuo to give 3 (158 mg, 72%) as a yellow oil.
12
390.1188 [Mϩ]; calcd. for
C
1H2511B2127I 390.1187 (∆m ϭ 0.1
18
12
1H NMR: δ ϭ 0.99 (t, 3JH,H ϭ 7.6 Hz, 6 H, CH3), 1.37 (t, 3JH,H ϭ mmu); m/z ϭ 340.2532 (6b)ϩ; calcd. for
7.6 Hz, 6 H, CH3), 1.94 (m), 2.36 (m) (8 H, CH2), 7.37Ϫ7.56 (m, (∆m ϭ Ϫ0.2 mmu).
10 H, aromatic H) ppm. 11B NMR: δ ϭ 14.8 (br., Bbasal), Ϫ52.8 (s,
C
24
1H3011B2 340.2534
2,3,4,5-Tetraethyl-1-iodo-6-(trimethylstannyl)-2,3,4,5-tetracarba-
nido-hexaborane(6) (7a): A solution of 1 (194 mg, 0.44 mmol) in
hexane (10 mL) was added to a suspension of Me3SnLi (1 mmol)
in hexane (20 mL) at Ϫ60 °C. The mixture was allowed to warm
to room temp., stirred for 3 d and then filtered. The light-yellow
filtrate was dried in vacuo to give 7a (170 mg, 81%) as a yellow oil,
Bapical) ppm. 13C NMR: δ ϭ 13.7, 15.1 (CH3), 18.8, 19.2 (CH2),
signals of B-bound basal C atoms not observed, 116.1 (skeletal C
atoms non-adjacent to the basal B atom), 127.2, 128.5, 134.4, 138.2
(aromatic C) ppm; signals of alkynyl C atoms not observed.
31P{1H} NMR (CDCl3, 80.92 MHz): δ ϭ Ϫ40.1 ppm. EI-MS:
m/z (%) ϭ 498 (59.1) [Mϩ], 371 (9.8) [Mϩ Ϫ I], 186 (100) [HPPh2].
1
and a trace amount of 7b. H NMR: δ ϭ 0.3 (s, 9 H, SnMe3), 1.2
HR-MS (EI): m/z ϭ 498.1307 [Mϩ]; calcd. for 12C24 H3011B2127I31P
498.1316 (∆m ϭ Ϫ0.9 mmu).
1
(br., 6 H, CH3), 1.3 (br., 6 H, CH3), 2.11 (m), 2.24 (m) (8 H, CH2)
ppm. 11B NMR: δ ϭ 16.1 (br., Bbasal), Ϫ52.6 (s, Bapical) ppm. 13C
NMR: δ ϭ Ϫ6.0 (SnMe3), 13.5, 14.1 (CH3), 19.2, 22.2 (CH2), sig-
nals of B-bound basal C atoms not observed, 118.6 (skeletal C
atoms non-adjacent to the basal B atom) ppm. 119Sn NMR
(CDCl3, 74.5 MHz): δ ϭ Ϫ97.9 ppm. EI-MS: m/z (%) ϭ 463 (100)
6-[Dicarbonyl(η5-cyclopentadienyl)iron]-2,3,4,5-tetraethyl-1-iodo-
2,3,4,5-tetracarba-nido-hexaborane(6) (4): A solution of 1 (317 mg,
0.72 mmol) in hexane (10 mL) was added to a suspension of K[(η5-
C5H5)Fe(CO)2] (395 mg, 1.8 mmol) in toluene (30 mL) at room
temp. The mixture was stirred for 4 d and then filtered. The deep-
[Mϩ Ϫ CH3], 499 (68.5) [7bϩϪ CH3]. HR-MS (EI): m/z ϭ 463.0254
red filtrate was concentrated and cooled to Ϫ28 °C; yellow crystals [Mϩ Ϫ CH3]; calcd. for
C
1H2611B2127I120Sn 463.0288 (∆m ϭ
12
14
were formed after one week (258 mg, 73%), m.p. 132 °C. 1H NMR:
δ ϭ 1.2 (br., 6 H, CH3) , 1.3 (br., 6 H, CH3), 1.93 (m), 2.22 (m) (8
H, CH2), 4.8 (s, Cp) ppm. 11B NMR: δ ϭ 28.6 (br., Bbasal), Ϫ49.6
(s, Bapical) ppm. 13C NMR: δ ϭ 13.6, 14.1 (CH3), 19.3, 21.7 (CH2),
88.1 (Cp), 106.5 (B-bound basal C atoms), 117.9 (skeletal C atoms
non-adjacent to the basal B atom), 217.2 (CO) ppm; signals of
alkynyl C atoms not observed. IR (hexane): νco: 1998.1 (s), 1942.4
(s) cmϪ1. EI-MS: m/z (%) ϭ 490 (4.2) [Mϩ], 462 (24.1) [Mϩ Ϫ CO],
434 (100) [Mϩ Ϫ 2 CO], 405 (7.3) [Mϩ Ϫ 2 CO Ϫ Et], 307 (22.9)
Ϫ3.4 mmu); m/z
ϭ
501.0996 [7bϩ
1H3511B2120Sn2 501.0968 (∆m ϭ 2.8 mmu).
Ϫ CH3]; calcd. for
12
C
17
2,3,4,5-Tetraethyl-6-(phenylethynyl)-1-(trimethylsilylethynyl)-
2,3,4,5-tetracarba-nido-hexaborane(6) (8): A portion of lithium tri-
methylsilylacetlylide (138 mg, 1.33 mmol) was dissolved in THF
(15 mL) at room temp. and ZnCl2 (180 mg, 1.33 mmol) was added.
The mixture was stirred for 3 h and was then added to a mixture of
2a (146 mg, 0.35 mmol) and Pd(PPh3)4 (20 mg, 0.017 mmol). The
resulting yellow mixture was stirred for 3 d and then heated at
reflux for 10 d. The solvent was removed, the black residue was
extracted with hexane (2 ϫ 20 mL) and filtered. The yellow filtrate
was dried in vacuo to give a yellow viscous oil. A minimum amount
of hexane was added and, on cooling to Ϫ28 °C, yellow crystals of
8 (115 mg, 85%) grew, m.p. 72 °C. 1H NMR: δ ϭ 0.08 (SiMe3),
[Mϩ Ϫ 2 CO Ϫ I]. HR-MS (EI): m/z ϭ 490.0431 [Mϩ]; calcd. for
12
C
19
1H25O211B2Fe127I 490.0435 (∆m ϭ Ϫ0.4 mmu).
2,3,4,5-Tetraethyl-6-hydrido-1-iodo-2,3,4,5-tetracarba-nido-hexa-
borane(6) (5). a) By Decomposition of 4: In an attempt to separate
4 by column chromatography on silica gel, the crude product was
eluted with hexane; only decomposition was observed. Compound
5 and paramagnetic impurities were formed, as indicated by the
NMR spectroscopy. b) By Reaction of 1 with LiBEt3H: A solution
3
3
1.22 (t, JH,H ϭ 7.6 Hz, 6 H, CH3), 1.30 (t, JH,H ϭ 7.6 Hz, 6 H,
CH3), 2.22 (m), 2.35 (m) (8 H, CH2), 7.27Ϫ7.50 (m, 5 H, Ph) ppm.
11B NMR: δ ϭ 9.8 (s, Bbasal), Ϫ50.7 (s, Bapical) ppm. 13C NMR:
of LiBEt3H (1.0  in THF, 0.4 mmol) was added dropwise at Ϫ65 δ ϭ 0.01 (SiMe3), 13.6, 14.7 (CH3), 17.4, 19.1 (CH2), 104.4 (B-
°C to a solution of 1 (194 mg, 0.44 mmol) in hexane (5 mL). A
bound basal C atoms), 112.4 (skeletal C atoms non-adjacent to the
basal B atom), 125.0, 127.4, 128.0, 131.7 (Ph) ppm; signals of alky-
white precipitate was formed, the mixture was allowed to warm to
room temp. and filtered. The colorless filtrate was dried in vacuo nyl C atoms not observed. 29Si NMR (CDCl3, 39.7 MHz): δ ϭ
1
to give 5 (123 mg, 89%) as a colorless oil. H NMR: δ ϭ 1.2 (br.,
Ϫ19.4 ppm. EI-MS: m/z (%) ϭ 384 (100) [Mϩ]. HR-MS (EI):
6 H, CH3), 1.2 (br., 6 H, CH3), 2.04 (m), 2.21 (m) (8 H, CH2) ppm. m/z ϭ 384.2621 [Mϩ]; calcd. for 12C25 H3411B228Si 384.2616 (∆m ϭ
1
11B NMR: δ ϭ 11.5 (d, JB,H ϭ 148.3 Hz, Bbasal), Ϫ53.8 (s, Bapical
)
0.5 mmu).
ppm. 13C NMR: δ ϭ 13.1, 14.3 (CH3), 18.5, 20.1 (CH2), 106.3 (B-
bound basal C atoms), 114.8 (skeletal C atoms non-adjacent to the
basal B atom) ppm. EI-MS: m/z (%) ϭ 314 (100) [Mϩ], 187 (10)
3-Carboranyl-4-phenyl-1,2-bis(tricarbonylcobalta)tetrahedrane (9):
A solution of 2a (193 mg, 0.47 mmol) in hexane (15 mL) was added
to a solution of Co2(CO)8 (178 mg, 0.52 mmol) in hexane (15 mL)
at Ϫ40 °C. The mixture was allowed to warm to room temp. and
stirred for 4 d until the reaction was complete. The solvent was
removed in vacuo and the black residue was extracted with di-
chloromethane (2 mL) and separated by column chromatography
(Florisil) with hexane as eluent. After a small amount of un-
changed Co2(CO)8, a deep-brown band was eluted. The solution
was concentrated and cooled to Ϫ28 °C to give black crystals of 9
(170 mg, 52%), m.p. 140Ϫ141 °C (decomp.). 1H NMR: δ ϭ 1.09
(br., 6 H, CH3), 1.35 (br., 6 H, CH3), 1.84 (br.), 2.28 (br.) (8 H,
[Mϩ Ϫ I]. HR-MS (EI): m/z ϭ 314.0893 [Mϩ]; calcd. for
C
12
1H2111B2127I 314.0874 (∆m ϭ 1.9 mmu).
12
2,3,4,5-Tetraethyl-1-iodo-6-phenyl-2,3,4,5-tetracarba-nido-hexa-
borane(6) (6a): A suspension of PhLi [obtained upon solvent re-
moval from a solution (1.6 ) in diethyl ether/cyclohexane, 1 mmol]
in hexane (5 mL) was cooled to Ϫ60 °C and added to a solution
of 1 (194 mg, 0.44 mmol) in hexane (10 mL). The mixture was al-
lowed to warm to room temp., stirred overnight and filtered. The
light-yellow filtrate was dried in vacuo to give 6a (150 mg, 87%) as
a colorless oil, and trace amount of 6b. 1H NMR: δ ϭ 1.19 (t, CH2), 7.26Ϫ7.51 (m, 5 H, Ph) ppm. 11B NMR: δ ϭ 16.3 (br.,
3JH,H ϭ 7.6 Hz, 6 H, CH3), 1.4 (t, 3JH,H ϭ 7.6 Hz, 6 H, CH3), 2.08 Bbasal), Ϫ51.1 (s, Bapical) ppm. 13C NMR: δ ϭ 13.6, 14.1 (CH3),
(m), 2.36 (m) (8 H, CH2), 7.40Ϫ7.55 (m, Ph) ppm. 11B NMR: δ ϭ 18.6, 19.0 (CH2), 102.6 (B-bound basal C atoms), 114.0 (skeletal C
17.9 (s, Bbasal), Ϫ52.4 (s, Bapical) ppm. 13C NMR: δ ϭ 13.7, 14.2
(CH3), 18.5, 19.0 (CH2), 103.4 (br., B-bound basal C atoms), 112.9
(skeletal C atoms non-adjacent to the basal B atom), 126.8, 127.2,
atoms non-adjacent to the basal B atom), 127.2, 128.4, 129.7 (Ph),
200.4 (CO) ppm. EI-MS: m/z (%) ϭ 672 (13.0) [Mϩ Ϫ CO], 644
(12.1) [Mϩ Ϫ 2 CO], 616 (19.0) [Mϩ Ϫ 3 CO], 588 (28.2) [Mϩ
Ϫ
128.8, 133.2, 141.3 (Ph) ppm. EI-MS: m/z (%) ϭ 390 (100) [Mϩ], 4 CO], 560 (11.7) [Mϩ Ϫ 5 CO], 532 (100) [Mϩ Ϫ 6 CO], 473 (20.6)
361 (10.8) [Mϩ Ϫ Et], 263 (5.9) [Mϩ Ϫ I]. HR-MS (EI): m/z ϭ [Mϩ Ϫ 6 CO Ϫ 2 Et]. HR-MS (EI): m/z ϭ 671.9595 [Mϩ Ϫ CO];
2430
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2004, 2425Ϫ2433

Synthesis and Structures of New C4B2-nido-carborane Derivatives
FULL PAPER
12
calcd. for
C
25
1H25O511B2Co2127I 671.9596 (∆m ϭ Ϫ0.1 mmu). filtered. The light-yellow filtrate was dried in vacuo, the residue
C26H25B2Co2IO6 (699.9): calcd. C 44.62, H 3.60; found C 44.08,
H 3.98.
was extracted with hexane (2 ϫ 20 mL) and filtered. The colorless
filtrate was dried in vacuo to give 11 as an oil (90 mg, 50%). 1H
NMR: δ ϭ 1.2 (br., 6 H, CH3), 1.3 (br., 6 H, CH3), 2.10 (m), 2.32
(m) (8 H, CH2), 7.41 (d, J ϭ 8 Hz, 4 H), 7.48 (d, J ϭ 8 Hz, 4 H,
C6H4C6H4) ppm. 11B NMR: δ ϭ 22.0 (br., 2 B, Bbasal), Ϫ52.4 (s, 2
B, Bapical) ppm. 13C NMR: δ ϭ 13.4, 14.3 (CH3), 18.4, 19.8 (CH2),
104.4 (B-bound basal C atoms), 113.0 (skeletal C atoms non-adjac-
ent to the basal B atom), 124.6, 127.6, 128.1, 131.7 (C6H4C6H4)
6-(o-Carboranyl)-2,3,4,5-tetraethyl-1-iodo-2,3,4,5-tetracarba-nido-
hexaborane(6) (10): nBuLi (2.5  in hexanes, 0.4 mL, 1 mmol) was
added at Ϫ65 °C to
a solution of o-carborane (126 mg,
0.875 mmol) in toluene (15 mL). The colorless mixture was allowed
to warm to room temp. and stirred overnight. The resulting white
suspension was cooled to Ϫ65 °C and a solution of 1 (264 mg,
0.58 mmol) in hexane (7 mL) was added. The mixture was warmed
to room temp., heated at reflux overnight, and filtered. The color-
less filtrate was dried in vacuo to give a solid. A minimum amount
ppm. FAB-MS: m/z (%) ϭ 778 (100) [Mϩ]. HR-MS (FAB): m/z ϭ
778.2294 [Mϩ]; calcd. for
mmu).
C
36
1H4811B4127I2 778.2217 (∆m ϭ 7.7
12
of CDCl3 was added and, on cooling to Ϫ28 °C, colorless crystals The Oxygen-Bridged Carborane 12: Wet Et3N (92 mg) was added
of 10 (200 mg, 76%) were obtained, m.p. 108 °C. 1H NMR: δ ϭ to a solution of 1 (198 mg, 0.45 mmol) in hexane (5 mL) at Ϫ 60
3
3
1.20 (t, JH,H ϭ 7.6 Hz, 6 H, CH3), 1.28 (t, JH,H ϭ 7.6 Hz, 6 H, °C. The mixture was allowed to warm to room temp. and stirred
CH3), 1.93 (m), 2.25 (m) (8 H, CH2), 3.3Ϫ3.8 (m, o-carborane) overnight. The colorless filtrate and the white precipitate were then
ppm. 11B{1H} NMR: δ ϭ 13.9 (s, Bbasal), Ϫ2.4 (2 B), Ϫ9.2 (2 B), separated by filtration. The filtrate was dried in vacuo to give 12
Ϫ13.6 (4 B), Ϫ14.8 (2 B), Ϫ53.4 (s, Bapical) ppm. 13C NMR: δ ϭ as an oil (100 mg, 69%). 11B NMR: δ ϭ 22.1 (br., 2 B, Bbasal),
13.6, 14.7 (CH3), 17.4, 19.1 (CH2), 59.6 (Ccage), 102.3 (br., B-bound
Ϫ51.9 (s, 2 B, Bapical) ppm. EI-MS: m/z (%) ϭ 642 (100) [Mϩ], 613
basal C atoms), 114.5 (skeletal C atoms non-adjacent to the basal
(61.2) [Mϩ Ϫ Et], 515 (48.6) [Mϩ Ϫ I]. HR-MS (EI): m/z ϭ
B atom) ppm. EI-MS: m/z (%) ϭ 456 (100) [Mϩ]. HR-MS (EI): 642.1533 (100) [Mϩ]; calcd. for
C
24
1H4011B4127I216O 642.1541
12
m/z ϭ 458.2604 [Mϩ]; calcd. for 12C14 H31
B
12
127I 458.2587 (∆m ϭ
(∆m ϭ Ϫ0.8 mmu). Negative FAB-MS of the white precipitate ex-
hibited peaks at m/z ϭ 356 [Et3NH]I2Ϫ, 483 [Et3NH]I3Ϫ, 584.9
[Et3NH]2I3Ϫ, indicating its identity as [Et3NH]I.
1
11
1.7 mmu).
The C6H4C6H4-Connected Carborane 11: nBuLi (2.5  in hexanes,
0.6 mL, 1.5 mmol) was added to a solution of 4,4Ј-dibromobiphe-
nyl (164 mg, 0.53 mmol) in THF (15 mL) at Ϫ65 °C, and stirred at
that temp. for 2 h. ZnCl2 (150 mg, 1.1 mmol) was added in one
X-ray Structure Determinations: Crystal data and details of the
structure determinations are listed in Tables 1 and 2. The intensity
data for 2a, 4, 8, 9, and 10 were collected with a Bruker AXS Smart
portion to the resulting white suspension. The mixture was allowed CCD diffractometer at 103(2) K, and for 2d at 298 K (Mo-Kα radi-
˚
to warm to room temp. to form a cloudy mixture, which was dried,
ation, λ ϭ 0.71073 A, graphite monochromator, ω-scans). Data
and dry toluene (25 mL), 1 (200 mg, 0.45 mmol, in 5 mL of hexane)
were corrected for Lorentz polarization and absorption effects
and Pd(PPh3)4 (60 mg, 0.052 mmol) were added to the solid. The (semiempirical, SADABS[17]). The structures were solved by direct
resulting yellow mixture was stirred at room temp. for 3 d and
methods (SHELXS-86)[18] and refined by least-squares methods
Table 1. Crystal data and structure refinement for 2a, 2d, 4
2a
2d
4
Empirical formula
Formula mass
Crystal system
Space group
C20H25B2I
413.92
C21H27B2I
427.95
C19H25B2FeIO2
489.76
monoclinic
P21/c
9.5495(5)
24.2877(11)
8.9340(4)
90
99.480(1)
90
2043.8(2)
4
1.592
2.257
976
triclinic
triclinic
¯
¯
P1
P1
˚
a [A]
7.3783(6)
10.4260(8)
12.5718(9)
86.083(1)
86.301(1)
85.441(2)
960.09(13)
2
7.8362(4)
8.3469(4)
18.2876(10)
80.286 (1)
85.038(1)
64.989(1)
1068.29(9)
2
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
3
˚
V [A ]
Z
Dcalcd. [g cmϪ3
]
1.432
1.664
416
1.330
1.498
432
µ(Mo-Kα) [mmϪ1
F(000)
]
Crystal size [mm]
Θmax [°]
0.35 ϫ 0.09 ϫ 0.04
32.0
Ϫ10/10, Ϫ15/15, Ϫ0/18
16837
0.45 ϫ 0.32 ϫ 0.27
26.3
Ϫ9/9, Ϫ10/10, 0/22
13336
0.32 ϫ 0.25 ϫ 0.20
32.0
Ϫ14/14, 0/36, 0/13
27347
Index ranges
Reflections collected
Independent (Rint
No. of parameters
GooF
)
6504 (0.0387)
308
1.071
4370(0.0210)
319
1.064
7027(0.0239)
326
1.215
R1 (I Ͼ 2σI)
wR2 (all reflections)
Resid. electron dens. [e·A
0.0304
0.077
1.322/Ϫ1.248
0.0404
0.1092
0.973/Ϫ0.623
0.0290
0.0670
1.292/Ϫ0.713
Ϫ3
˚
]
Eur. J. Inorg. Chem. 2004, 2425Ϫ2433
www.eurjic.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2431

Y. Nie, H. Pritzkow, W. Siebert
FULL PAPER
Table 2. Crystal data and structure refinement for 8, 9 and 10
8
9
10
Empirical formula
Formula mass
Crystal system
Space group
C25H34B2Si
384.23
monoclinic
P21
7.3346(4)
8.9453(4)
19.1092(10)
90
91.254(1)
90
1253.46(11)
2
1.018
0.101
416
C26H25B2Co2IO6
699.84
monoclinic
P21/c
16.7233(9)
12.4541(7)
13.5390(8)
90
93.599(1)
90
2814.3(3)
4
1.652
2.313
1384
C14H31B12I·2(C2H12B10)
744.44
monoclinic
P2/c
26.1136(12)
6.8725(3)
24.6178(12)
90
115.469(1)
90
3988.7(3)
4
˚
a [A]
˚
b [A]
˚
c [A]
α [°]
β [°9
γ [°]
3
˚
V [A ]
Z
Dcalcd. [g cmϪ3
]
1.240
0.821
1504
µ(Mo-Kα) [mmϪ1
F(000)
]
Crystal size [mm]
Θmax [°]
0.15 ϫ 0.24 ϫ 0.36
32.01
Ϫ10/10, Ϫ10/13, Ϫ0/28
11997
0.33 ϫ 0.10 ϫ 0.06
32.0
Ϫ24/24, 0/18, 0/20
37985
0.55 ϫ 0.30 ϫ 0.23
32.0
Ϫ38/35, 0/10, 0/36
53142
Index ranges
Reflections collected
Independent (Rint
No. of parameters
GooF
)
6728 (0.0247)
389
1.066
9662(0.0429)
434
1.050
13706(0.0342)
680
1.114
R1 (I Ͼ 2σI)
wR2 (all reflections)
Resid. electron dens. (e·A
0.0385
0.1018
0.393/Ϫ0.180
0.0318
0.0780
1.002/Ϫ0.522
0.0348
0.0819
1.197/Ϫ1.009
Ϫ3
˚
)
[3f]
based on F2 with all measured reflections (SHELXL-97).[18] All
non-hydrogen atoms were refined anisotropically. CCDC-221474
(2a), -221475 (2d), -221476 (4), -221477 (8), -221478 (9) and
-221479 (10) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge at
www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge
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2432
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Eur. J. Inorg. Chem. 2004, 2425Ϫ2433

Synthesis and Structures of New C4B2-nido-carborane Derivatives
FULL PAPER
G. M. Sheldrick, SADABS, Univ. Göttingen, 1999.
G. M. Sheldrick, SHELXS-86, Univ. Göttingen, 1986; G. M.
Sheldrick, SHELXL-97, Univ. Göttingen, 1997.
Received December 16, 2003
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Early View Article
Published Online April 20, 2004
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2433