Stepwise and selective carborane substitution in the B(3,6) positions of a 16 e CpCo half-sandwich complex containing a chelating ortho -carborane-1,2-dithiolate ligand

Article abstract of DOI:10.1021/ic1001804

The reactions of the 16e half-sandwich complex, CpCo(S₂C ₂B₁₀H₁₀) (1), with alkynones at ambient temperature lead to complexes CpCo(S₂C₂B ₁₀H₉)(CH - CH-C(O)R) (R = Ph (2), 2-naphthyl (3)). Both 2 and 3 are still 16e half-sandwich complexes containing a B(3)-substituted ortho-carborane-1,2-dithiolate ligand. Treatment of 2 with excess alkynes R ₁C - CR₂ (R₁ = H, R₂ = Ph, C(O)Ph, CO₂Me; R₁ = R₂ = CO₂Me) affords five complexes, CpCo(S₂C₂B₁₀H₈)(CH ₂CPh)(CH - CH-C(O)Ph) (4), CpCo(S₂C₂B ₁₀H₈)(CH - CH-C(O)Ph)₂ (5), CpCo(S ₂C₂B₁₀H₈)(CH - CH-CO ₂Me)(CH - CH-C(O)Ph) (6), CpCo(S₂C₂B ₁₀H₉)(MeO₂C-C - C-CO₂Me)(CH - CH-C(O)Ph) (7), and CpCo(S₂C₂B₁₀H ₉)(MeO₂C-C - C-CO₂Me)₂(CH - CH-C(O)Ph) (8). Complex 4 is an 18e complex bearing a B-CH₂ unit. Both 5 and 6 retain a 16e half-sandwich structure but contain a B(3,6)-disubstituted ortho-carborane-1,2-dithiolate ligand. However, in 7 and 8 one or two alkynes are inserted into one of the Co-S bonds to generate 18e species, respectively. Heating 7 leads to the 16e complex, CpCo(S ₂C₂B₁₀H₈)(MeO₂C-C - CH-CO₂Me)(CH - CH-C(O)Ph) (9), having a B(3,6)-disubstituted ortho-carborane-1,2-dithiolate ligand as in 5 and 6. All complexes were fully characterized by spectroscopic techniques and elemental analysis. The solid-state structures of 2 and 3 and 5-9 were further characterized by X-ray structural analysis.

Full text of DOI:10.1021/ic1001804

Inorg. Chem. 2010, 49, 3911–3917 3911
DOI: 10.1021/ic1001804
Stepwise and Selective Carborane Substitution in the B(3,6) Positions of a 16e CpCo
Half-Sandwich Complex Containing a Chelating ortho-Carborane-1,2-dithiolate Ligand
Yuguang Li,† Qibai Jiang,† Xiaolei Zhang,† Yizhi Li,† Hong Yan,*,† and Vladimir I. Bregadze*,‡
†State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering,
Nanjing University, Jiangsu 210093, China, and, and ‡A. N. Nesmeyanov Institute of Organoelement
Compounds (INEOS), Russian Academy of Sciences, Moscow 119991, Russia
Received January 29, 2010
The reactions of the 16e half-sandwich complex, CpCo(S2C2B10H10) (1), with alkynones at ambient temperature lead to
complexes CpCo(S2C2B10H9)(CHdCH-C(O)R) (R = Ph (2), 2-naphthyl (3)). Both 2 and 3 are still 16e half-sandwich
complexes containing a B(3)-substituted ortho-carborane-1,2-dithiolate ligand. Treatment of 2 with excess alkynes
R1CtCR2 (R1 = H, R2 = Ph, C(O)Ph, CO2Me; R1 = R2 = CO2Me) affords five complexes, CpCo(S2C2B10H8)(CH2CPh)-
(CHdCH-C(O)Ph) (4), CpCo(S2C2B10H8)(CHdCH-C(O)Ph)2 (5), CpCo(S2C2B10H8)(CHdCH-CO2Me)(CHdCH-
C(O)Ph) (6), CpCo(S2C2B10H9)(MeO2C-CdC-CO2Me)(CHdCH-C(O)Ph) (7), and CpCo(S2C2B10H9)(MeO2C-
CdC-CO2Me)2(CHdCH-C(O)Ph) (8). Complex 4 is an 18e complex bearing a B-CH2 unit. Both 5 and 6 retain a 16e
half-sandwich structure but contain a B(3,6)-disubstituted ortho-carborane-1,2-dithiolate ligand. However, in 7 and 8 one or
two alkynes are inserted into one of the Co-S bonds to generate 18e species, respectively. Heating 7 leads to the 16e
complex, CpCo(S2C2B10H8)(MeO2C-CdCH-CO2Me)(CHdCH-C(O)Ph) (9), having a B(3,6)-disubstituted ortho-
carborane-1,2-dithiolate ligand as in 5 and 6. All complexes were fully characterized by spectroscopic techniques and
elemental analysis. The solid-state structures of 2 and 3 and 5-9 were further characterized by X-ray structural
analysis.
Introduction
are capable of combining metal species to generate new types
of metal-metal binding complexes with one or two ortho-
carborane-1,2-dichalcogenolate ligands1 and with Lewis
Mononuclear 16e half-sandwich complexes Cp#M-
(E2C2B10H10) (Cp# = Cp, Cp*; M = Co, Rh, Ir; and E =
S, Se) and (p-cymene)M(S2C2B10H10) (M = Ru, Os) posses-
sing an ortho-carborane-1,2-dichalcogenolate ligand have
been described extensively.1-14 These sterically congested,
coordinatively unsaturated complexes are stable starting
materials and exhibit rich chemistries. For example, they
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2010 American Chemical Society
Published on Web 03/19/2010
pubs.acs.org/IC

3912 Inorganic Chemistry, Vol. 49, No. 8, 2010
Li et al.
Scheme 1. Some Reported Examples6,7,11 Possessing an ortho-Carborane-1,2-dichalcogenolate Ligand
Scheme 2. Reactions of 1with HCtC-C(O)R(R=Ph(2), 2-Naphthyl
(3)) and the Further Reactions of 2 with Alkynes
bases including biologically interesting substrates, such as
NH3, CO, and diazenes, to generate their 18e congeners.2,3
Furthermore, the combination of electron deficiency at the
metal center and reactivity of metal-chalcogen bonds ren-
ders these complexes interesting candidates for reactions with
unsaturated substrates, such as alkynes.4-14 Additionally,
both the bulky ancillary aromatic ligand and the closo-
dicarba-dodecaborane unit could protect the inner coordina-
tion sphere and make the catalytic oligmerization of alkyne
possible.10-13 Very recently we have reported the interesting
anticancer actions of two ruthenium complexes with an
ortho-carborane-1,2-dithiolate ligand.14
The B-H activation of the polyhedral carborane is concei-
vable if the electron deficient metal atom is located in close
proximity to the B-H vertices.15 Recently, some highly sub-
stituted carborane derivatives have been prepared by metal-
mediated catalytic dehydrogenative borylation,16 and the poly-
ethylated icosahedral carborane monoanions may be poten-
tially used as weakly coordinating anions.17 In the presence of
selected alkynes, the electronically unsaturated (16e) complexes
Cp*M(E2C2B10H10) (Cp* = pentamethylcyclopentadienyl;
M = Rh, Ir; and E = S, Se) have been reported to promote
hydroboration of the ortho-carborane cage in the B(3,6) posi-
tions (Scheme 1).5-12 Other selective substitution at the icosa-
hedral ortho-carborane cage has been accomplished as well.18
Recently, we have extended the reaction system to cobalt
and found that the 16e complexes CpCo(E2C2B10H10) (Cp =
cyclopentadienyl; and E = S, Se) are more reactive than the
analogous rhodium and iridium species (Scheme 1).5-12 Even
so, through choice of the compatibility between the 16e
species and alkyne as well as of the reaction ratio, we could
control the selective B-H functionalization at the ortho-
carborane cage step by step. Herein, we report such an
example that the reactions of the 16e complex CpCo-
(S2C2B10H10) (1) with HCtC-C(O)R (R = Ph, 2-naphthyl)
lead to 16e half-sandwich complexes 2 and 3 containing a
B(3)-monosubstituted ortho-carborane-1,2-dithiolate ligand
and then 2 further reacts with different alkynes.
(15) (a) Wilczynski, R.; Sneddon, L. G. Inorg. Chem. 1982, 21, 506–514.
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1693–1694. (c) Hewes, J. D.; Kreimendahl, C. W.; Marder, T. B.; Hawthorne,
M. F. J. Am. Chem. Soc. 1984, 106, 5757–5759. (d) Mazighi, K.; Carroll, P. J.;
Sneddon, L. G. Inorg. Chem. 1993, 32, 1963–1969. (e) Kadlecek, D. E.; Carroll,
P. J.; Sneddon, L. G. J. Am. Chem. Soc. 2000, 122, 10868–10877. (f ) Pender,
M. J.; Carroll, P. J.; Sneddon, L. G. J. Am. Chem. Soc. 2001, 123, 12222–12231.
(16) Herzog, A.; Maderna, A.; Harakas, G. N.; Knobler, C. B.;
Hawthorne, M. F. Chem. Eur. J. 1999, 5, 1212–1217.
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(17) (a) Molinos, E.; Kociok-Kohn, G.; Weller, A. S. Chem. Commun.
Results and Discussion
€
2005, 3609–3611. (b) Molinos, E.; Brayshaw, S. K.; Kociok-Kohn, G.; Weller,
Synthesis of 2 and 3. The reactions of the 16e complex,
[CpCo(S2C2B10H10)] (1), with alkynones HCtC-C(O)R
(R = Ph, 2-naphthyl) in a 1:1 ratio at ambient tempera-
ture lead to complexes 2 and 3, respectively (Scheme 2).
Their solid-state structures are shown in Figures 1 and 2,
A. S. Organometallics 2007, 26, 2370–2382.
€
(18) (a) Bregadze, V. I. Chem. Rev. 1992, 92, 209–223. (b) Korbe, S.;
Schreiber, P. J.; Michl, J. Chem. Rev. 2006, 106, 5208–5249. (c) Gr€uner, B.;
ꢀ
ꢁ
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Císarova, I.; Caslavskꢁy, J.; Bonnetot, B.; Cornu, D. Collect. Czech. Chem.
Commun. 2002, 67, 953–964. (d) Finze, M. Inorg. Chem. 2008, 47, 11857–
11867.

Article
Inorganic Chemistry, Vol. 49, No. 8, 2010 3913
Table 1. 1H and 13C NMR Data of the B-CHdCH-C(O)R unit (R = Ph,
2-naphthyl) in 2-9
1H
13C
complex
B-CHdCH
B-CHdCH
B-CdC
B-CdC
2
3
4
5
6
7
8
9
6.47
6.52
7.39
6.37
6.51
7.68
6.72
6.39
7.45
7.62
7.71
7.47
7.47
7.91
7.53
7.41
138.2
138.2
139.4
138.4
137.9
139.1
137.1
138.2
140.4 (br)
140.1 (br)
140.1 (br)
139.8 (br)
140.6 (br)
140.1 (br)
140.4 (br)
140.2 (br)
bonds, and potentially reactive BH vertice of the carborane
cage, thus may still possess the potential to complete further
chemical transformations. In this manuscript, we examined
the reactivity of 2 with alkynes.
˚
Figure 1. Molecular structure of 2. Selected bond lengths (A) and angles
(°): Co1-S1, 2.1425(8); Co1-S2, 2.1244(8); C1-C2, 1.633(4); C1-S1,
1.774(3); C2-S2, 1.790(3); C3-C4, 1.323(4); B3-C3, 1.543(5); S2-
Co1-S1, 96.69(3); C1-S1-Co1, 105.37(10); and C2-S2-Co1, 105.87(10).
Reaction of 2 with Phenylacetylene. The reaction of 2
with excess HCtC-Ph at ambient temperature leads to
the only product 4 in a yield of 69%. Unfortunately,
attempts to grow suitable single crystals for structural
determination failed. However, the spectroscopic data
support its structure, as proposed in Scheme 2. In the
1H NMR spectrum the broader doublets at 2.03 and
2.36 ppm are assigned to the new generated alkyl group
of the B-CH2 unit, and the large value (16 Hz) of the
geminal coupling constants 2J(1H, 1H) is typical for
diastereotopic 1H nuclei of the B-CH2 group. The broader
13C signal at 34.3 ppm also reflects that the CH2 group is
linked to a boron atom. Thus, the NMR data demon-
strate that the second B-substitution occurs with the gene-
ration of an alkyl B-CH2 unit. Another noticeable
feature includes that the second phenyl group appears
in one broad signal at 7.29 ppm, hence a 13C/1H HET-
COR (HMQC) experiment has to be used to recognize the
13C signals. The proton signal broadening of the phenyl
ring might be caused by its fast rotation in solution at
ambient temperature. Some examples with a similar
structure of a B-CH2 unit have been reported,7-11
including the one generated from the reaction of 1 with
HCtC-Ph.12 Additionally, in this system, the reaction
of phenyl acetylene leads to significant effects on the 1H
data of the existing B-CHdCH-C(O)Ph unit from 6.47
and 7.45 ppm in 1 to 7.39 and 7.71 ppm in 4 (Table 1).
Reaction of 2 with Phenyl Ethynyl Ketone. The reaction
of 2 with excess HCtC-C(O)Ph at ambient temperature
leads to 5 as the sole product in a yield of 63%. Its solid-state
structure (Figure 3) reveals that 5 is still a 16e half-sandwich
complex containing a B(3,6)-disubstituted ortho-carborane-
1,2-dithiolate ligand, and the olefinic substituents in B(3,6)
positions take E/E configurations.
˚
Figure 2. Molecular structure of 3. Selected bond lengths (A) and angles
(°): Co1-S1, 2.1164(9); Co1-S2, 2.1435(11); S1-C1, 1.779(3); S2-C2,
1.780(3); C1-C2, 1.654(3); B3-C8, 1.548(4); C8-C9, 1.300(4); S1-
Co1-S2, 97.26(4); C1-S1-Co1, 105.78(9); and C2-S2-Co1, 105.23(9).
respectively. Both are 16e half-sandwich complexes pos-
sessing B(3)-substituted ortho-carborane-1,2-dithiolate
ligand, and the CdC bond in the B-H functionalized
group of the alkyne takes an E configuration.
1
In the H NMR spectra the two doublets at 6.47 and
7.45 ppm in 2 and at 6.52 and 7.62 ppm in 3 are assigned to
the individual B-CHdCH unit (Table 1), and the large
coupling constant (J = 18 Hz) corresponds to an E config-
uration. Note that the resonance of the proton adjacent to
the boron atom shows the characteristic broader doublet
due to partially relaxed 1H-11B coupling. In the 13C NMR
spectrum of 2, the sharp 13C signal at 138.2 ppm and the
broader resonance at 140.4 ppm of the carbon nuclei linked
directly to B are indicative of the B-CHdCH unit, as
further confirmed by 13C/1H HETCOR (HMQC) experi-
ments. In 3, the corresponding 13C data are 138.2 and 140.1
ppm (Table 1). Therefore, the spectroscopic data are con-
sistent with their solid-state structures. Also, the molecular
ion peaks in the mass spectra and the elemental analysis data
further verify their structures.
The NMR data show that only one type of B-
CHdCH unit is present as only two doublets at 6.37
and 7.47 ppm appear in the H NMR spectrum. The
1
We have previously reported this type of the 16e
species, for example, II and IV in Scheme 1.6,11 However,
they were obtained from conversions of corresponding
precursors, for example, IfII and IIIfIV (Scheme 1)
upon heating. In this paper, the reactions of 1 with
alkynones provide a facile route to the selectively B-
monosubstituted ortho-carborane in one step.
coupling constant (J = 18 Hz) corresponds to an E
configuration. Correspondingly, in the 13C NMR spec-
trum one sharp 13C signal at 138.4 ppm and one broader
resonance at 139.8 ppm are assigned to the B-CHdCH
unit, as confirmed by 13C/1H HETCOR (HMQC) experi-
ment. The chemical shifts in 5 are similar to those in 2
(Table 1). However, its molecular ion peak in the mass
spectrum and the elemental analysis data can further
verify B(3,6)-disubstitution at carborane.
In contrast, 2 and 3 still have a coordinatively and electro-
nically unsaturated metal center (16e), reactive metal-sulfur

3914 Inorganic Chemistry, Vol. 49, No. 8, 2010
Li et al.
˚
Figure 3. Molecular structure of 5. Selected bond lengths (A) and angles
(°): Co1-S1, 2.1443(10); Co1-S2, 2.1387(10); C1-C2, 1.639(5); C1-S1,
1.776(3); C2-S2, 1.788(4); C3-C4, 1.312(5); B3-C3, 1.553(5); B6-C12,
1.550(6); C12-C13, 1.306(5); S2-Co1-S1, 96.90(4); C1-S1-Co1,
104.98(12); and C2-S2-Co1, 104.95(11).
˚
Figure 5. Molecular structure of 7. Selected bond lengths (A) and angles
(°): Co1-S1, 2.2722(10); Co1-S2, 2.2551(10); C1-C2, 1.651(4); C1-S1,
1.810(3); C2-S2, 1.774(3); B3-C14, 1.558(5); C9-C10, 1.297(4);
C9-Co1, 1.904(3); C10-S1, 1.802(3); C14-C15, 1.318(4); C1-S1-Co1,
104.91(11); C2-S2-Co1, 105.07(11); S2-Co1-S1, 94.14(3); C10-
S1-Co1, 77.98(11); C10-S1-C1, 102.44(13); C9-Co1-S1, 71.58(10);
C9-Co1-S2, 93.98(9); C10-C9-Co1, 106.5(2); and C9-C10-S1,
103.9(2).
˚
Figure 4. Molecular structure of 6. Selected bond lengths (A) and angles
(°): Co1-S1, 2.1373(9); Co1-S2, 2.1309(9); C1-S1, 1.777(3); C2-S2,
1.779(3); C1-C2, 1.626(4); B6-C17, 1.552(3); B3-C8, 1.523(5); C8-C9,
1.328(4); C17-C18, 1.332(4); S2-Co1-S1, 97.00(3); C1-S1-Co1,
104.69(9); and C2-S2-Co1 105.03(9).
˚
Figure 6. Molecular structure of 8. Selected bond lengths (A) and angles
Complex 5 can be also obtained from the reaction of 1
with excess HCtC-C(O)Ph at ambient temperature. We
have previously reported similar structures with two
equal substituents at B(3) and B(6) sites of ortho-carbor-
ane in the Co, Rh, and Ir systems by use of activated
alkynes.5,6,11
(°): Co1-S1, 2.1821(10); Co1-S2, 2.2589(10); C1-C2, 1.641(5); C1-S1,
1.864(4); C2-S2, 1.784(4); B3-C8, 1.559(5); C8-C9, 1.327(5); C17-
C18, 1.369(5); C17-S1, 1.783(4); C18-C19, 1.504(4); C19-C20, 1.375(5);
C20-Co1, 1.910(4); S1-Co1-S2, 93.78(4); C1-S1-Co1, 106.96(11);
C2-S2-Co1, 102.77(12); C17-S1-C1, 103.89(16); C17-S1-Co1,
113.93(11); C17-C18-C19, 130.2(3); C20-C19-C18, 124.1(3); and
C19-C20-Co1 130.4(3).
Reaction of 2 with Methyl Acetylene Monocarboxylate.
As shown in Scheme 2, the reaction of 2 with excess
HCtC-CO2Me at ambient temperature leads to 6 in a
yield of 66%. Its solid-state structure shows a 16e com-
plex, similar to 5, but contains two different olefinic
substituents in the B(3) and B(6) positions of ortho-
carborane in E and Z configurations, respectively
(Figure 4).
differing functional groups. In contrast to 5, 6 may be
predicted as a more efficient catalyst in alkyne cyclotri-
merization with higher regioselectivity owing to different
coordination environments around the metal center that
is generated by two different substituents at carborane.
Reaction of 2 with Dimethyl Acetylene Dicarboxylate.
The reaction of 2 with excess MeO2C-CtC-CO2Me at
ambient temperature leads to 7 and 8 in the yields of 62%
and 32%, respectively (Scheme 2). Their solid-state struc-
tures are shown in Figures 5 and 6, respectively. In each
case, the olefinic substituent in the B(3) position of
carborane retains an E configuration, as observed in 2.
But interestingly in 7, one alkyne is inserted into one of
the Co-S bonds to generate a four-membered ring
CoCCS which is on the opposite side with the
B-CHdCH-C(O)Ph unit. Whereas in 8, two alkynes
are inserted into one Co-S bond to form a six-membered
ring CoCCCCS which is on the same side, in contrast, to
the B-CHdCH-C(O)Ph unit.
The 1H NMR spectrum displays two pairs of two
doublets. One pair at 5.18 and 6.31 ppm is assigned to
the B-CHdCH-CO2Me unit with a coupling constant
of J = 15 Hz, corresponding to a Z configuration. The
other at 6.51 and 7.47 ppm is assigned to the B-CHd
CH-C(O)Ph unit with a coupling constant of J = 18 Hz,
corresponding to an E configuration. A 13C/1H hetero-
nuclear correlation (HMQC) experiment was used to
allow a complete assignment of the 13C signals. As a
result, the 13C signals at 134.4 and 134.8 (br. C-B) ppm
and 137.9 and 140.6 (br. C-B) ppm are, respectively,
assigned to the olefinic carbon atoms of the B-CHd
CH-CO2Me and B-CHdCH-C(O)Ph groups. The
NMR data are parallel to those in 5 and in the B-disub-
stituted complex CpCo(S2C2B10H8)(CHdCH-CO2Me)2.10
Clearly, the NMR data are in agreement with its solid-
state structure. The stepwise reaction provides an efficient
route in generation of B-disubstitution at carborane with
The NMR data support their solid-state structures. The
1H NMR spectra show characteristic doublets at 7.68 and
7.91 ppm in 7 and 6.72 and 7.53 ppm in 8 for the
individual B-CHdCH unit with a coupling constant of
J = 18 Hz, corresponding to the E configuration for both.
Compared to 2, considerable changes in the 1H values are

Article
Inorganic Chemistry, Vol. 49, No. 8, 2010 3915
with alkynes to generate 16e B-disubstituted species, such
as 5, 6, and 9, depending on the alkyne used. And the
different functional groups at carborane may induce
stereoselectivity of substrates to improve regioselectivity
of the products in alkyne cyclotrimerization mediated by
such species.
Conclusion
Through control of the ratio of the starting 16e complex
CpCo(S2C2B10H10) (1) and alkynone HCtC-C(O)R (R =
Ph, 2-naphthyl), the 16e half-sandwich complexes 2 and 3
possessing a B-monosubstituted ortho-carborane-1,2-dithio-
late ligand have been synthesized at ambient temperature.
Since these molecules still have a coordinatively and electro-
nically unsaturated metal center, reactive metal-sulfur bonds
as well as potentially reactive B-H bonds of the carborane
cage, they have shown further reactivity toward alkynes to
generate three types of products at ambient temperature,
depending on the alkyne used. The first type is the alkyne
insertion product including one or two alkynes inserted 18e
species when dimethyl acetylene dicarboxylate is applied; the
second type is the 18e product with a second B-H function-
alized group of a B-CH2 unit when a nonactivated terminal
alkyne, phenylacetylene, is used; and the third is the 16e half-
sandwich complex with B(3,6)-disubstitution at ortho-carbo-
rane if an activated terminal alkyne is used, for instance,
phenyl ethynyl ketone and methyl acetylene monocarboxy-
late. Through this investigation different products could be
obtained by choosing alkyne type. The most important point
is that this study provides a facile and straightforward way
for the stepwise and selective B-H functionalization at the
carborane cage.
˚
Figure 7. Molecular structure of 9. Selected bond lengths (A) and angles
(°): Co1-S1, 2.1261(8); Co1-S2, 2.1405(8); S1-C1, 1.776(3); S2-C2,
1.786(3); C1-C2, 1.656(4); C8-B3, 1.552(4); C8-C9, 1.335(4); C17-B6,
1.586(4); C17-C18, 1.302(4); S1-Co1-S2, 96.80(3); C1-S1-Co1,
105.70(10); and C2-S2-Co1 106.37(10).
observed, especially for 7 (Table 1). However, in the 13
C
NMR spectra the two olefinic carbon data of the B-
CHdCH units both in 7 and 8 are close to those in 2. The
13C values of the carbon atoms linked to cobalt are shifted
to a lower field, for example, at 189.4 ppm in 7 and
187.1 ppm in 8, owing to the metal effect on the 13C
nuclear shielding. This parallels to the cases of previously
reported Co, Rh, Ir, Ru, and Os analogues.7-12
Note that addition of one or two alkynes to a M-E
bond of the 16e species Cp#M(E2C2B10H10) (Cp# = Cp,
Cp*; M = Co, Rh, Ir; and E = S, Se) and (p-cymene)-
M(S2C2B10H10) (M = Ru, Os) to generate a four- or
six-membered ring has been extensively described.7-12
However, 7 is the first isolated example bearing both a
four-membered ring and a B-CHdCH-C(O)R group at
carborane. And 8 is the second example (the first is XIII in
Scheme 1) for such a structural type. Both are the key
intermediates to the metal-mediated B-disubstitution at
carborane and alkyne cyclotrimerization, respectively. So
far, this is the first reaction to produce both one- and two-
alkyne inserted complexes.
Experimental Section
General Procedures. The preparative work was carried out
under an argon atmosphere using standard Schlenk techniques.
Solvents were freshly distilled under nitrogen from either sodium
or calcium hydride prior to use. Aromatic alkynones HCtC-
C(O)R19 (R = Ph, 2-naphthyl) and CpCoS2C2B10H10 (1)20,4a were
prepared according to the literature methods. n-Butyllithium
(2.0 M in cyclohexane, Aldrich), phenylacetylene (Alfa Aesar),
methyl acetylene monocarboxylate (Alfa Aesar), and dimethyl
acetylene dicarboxylate (Aldrich) were used as commercial pro-
ducts without further purification.
Transformation of 7 at a Higher Temperature. In
Scheme 1 the one-alkyne inserted species I (E = S) could
convert to the B-monosubstituted species II.11 This pro-
vides direct evidence that the alkyne inserted species is the
early stage intermediate to metal-induced B-H activa-
tion and selective B-functionalization at carborane.5-12
˚
As the coordinative SfCo bond distance of 2.272 A in 7
˚
is longer than that of 2.246 A in I (E = S), 7 might further
Elemental analysis was performed in an elementar vario EL III
elemental analyzer. NMR data were obtained on a Bruker DRX-
500 spectrometer. Chemical shifts were given with respect to
CHCl3/CDCl3 (δ 1H = 7.24, δ 13C = 77.0) and external Et2O-
BF3 (δ 11B = 0). The IR spectra were recorded on a Bruker Vector
22 spectrophotometer with KBr pellets in the 4000-400 cm-1
region. The mass spectra were recorded on either a Micromass GC-
TOF for EI-MS (70 ev). Finnigan MAT TSQ7000 was used for
ESI-MS. X-ray crystallographic data21 were collected on a Bruker
SMART Apex II CCD diffractometer using graphite-monochro-
convert as well. Indeed, 7 could cleanly convert to its
geometrical isomer 9 upon heating at 70 °C (Scheme 2).
Its solid-state structure is shown in Figure 7.
Similar to 5 and 6, 9 is also a 16e half-sandwich complex
containing a B(3,6)-disubstituted ortho-carborane-1,2-
dithiolate ligand where both the olefinic substituents in
the B(3) and B(6) positions take E configurations. The 1H
NMR spectrum shows a singlet at 6.79 ppm for the vinyl
proton and two singlets at 3.80 and 3.86 ppm for the OMe
groups of the new generated B-C(CO2Me)dCH-CO2Me
unit. The olefinic 13C signal at 141.1 ppm for the dCH unit
of the B-C(CO2Me)dCH-CO2Me group is identified by
13C/1H heteronuclear correlation. The 1H and 13C data of
the existing B-CHdCH-C(O)Ph unit are similar to those
in 2, parallel to the analogues of 5 and 6 as well.
˚
mated Mo KR (λ = 0.71073 A) radiation. The intensities were
corrected for Lorentz polarization effects and empirical absorption
with the SADABS program. The structures were solved by direct
methods using the SHELXL-97 program. Details regarding data
(19) (a) Mortier, J.; Vaultier, M.; Carreaux, F.; Douin, J. M. J. Org.
Chem. 1998, 63, 3515–3516. (b) Caliendo, G.; Fiorino, F.; Perissutti, E.;
Severino, B.; Scolaro, D.; Gessi, S.; Cattabriga, E.; Borea, P. A.; Santagada, V.
Eur. J. Pharm. Sci. 2002, 16, 15–28.
(20) King, R. B. Inorg. Chem. 1966, 5, 82–87.
(21) Bruker; SMART, version 5.0; SAINT, version 6; SHELXTL, version 6.1;
SADABS, version 2.03; Bruker AXS Inc.: Madison, WI, 2000.
Alternatively, 9 could be generated from the reaction of
the 16e complex II (Scheme 1) with HCtC-C(O)Ph
at ambient temperature. Therefore, a 16e complex with
B-monosubstitution at carborane could continue to react

3916 Inorganic Chemistry, Vol. 49, No. 8, 2010
Li et al.
Table 2. Crystallographic Data and Structural Refinement Details of 2, 3, 5, and 6
2
3
5
6
chemical formula
crystal size (mm)
formula weight
temperature (K)
radiation
C16H21B10CoOS2
0.30 ꢀ 0.26 ꢀ 0.24
460.48
C20H23B10CoOS2
0.40 ꢀ 0.36 ꢀ 0.28
510.53
C25H27B10CoO2S2
0.30 ꢀ 0.26 ꢀ 0.22
590.62
C40H52B20Co2O7S4
0.30 ꢀ 0.25 ꢀ 0.24
1107.12
291(2)
293(2)
291(2)
Mo KR (0.71073 A)
291(2)
˚
˚
˚
˚
Mo KR (0.71073 A)
monoclinic
P2(1)/c
Mo KR (0.71073 A)
triclinic
P-1
Mo KR (0.71073 A)
monoclinic
P2(1)/c
crystal system
space group
orthorhombic
P2(1)2(1)2(1)
7.9575(8)
15.6813(14)
22.837(2)
90.00
90.00
90.00
2849.7(5)
4
1.377
˚
a (A)
11.0395(11)
11.9960(12)
16.9848(17)
90.00
99.827(2)
90.00
2216.3(4)
4
1.380
0.969
936
7.071(3)
11.578(3)
14.990(5)
83.297(4)
78.928(4)
86.111(2)
1194.8(6)
2
9.2832(9)
22.806(2)
24.997(3)
90.00
95.409(2)
90.00
5268.7(9)
4
1.396
0.835
2264
˚
b (A)
˚
c (A)
R (°)
β (°)
γ (°)
3
˚
V (A )
Z
F
calc (g cm-3
)
1.419
0.907
520
3
absorp. coeff. (mm-1
F(000)
)
0.773
1208
θ range (°)
reflns collected
indep. reflns
2.09-26.00
11 924 (Rint = 0.0442)
4346
1.77-26.00
6549 (Rint = 0.0571)
4617
1.78-26.00
15 685 (Rint = 0.0433)
5599
1.64-26.00
28 460 (Rint = 0.0465)
10 295
refns obs. [I >2σ(I)]
data /restr./paras
GOF
2840
4346/0/271
1.044
3288
4617/0/307
1.029
4294
5599/0/361
0.992
7482
10 295/0/660
1.029
R1/wR2I > 2σ(I)]
R1/wR2 (all data)
larg. peak/hole (e A
0.0405/0.0841
0.0725/0.0936
0.446/-0.372
0.0422/0.0924
0.0603/0.0969
0.339/-0.302
0.0420/0.0865
0.0585/0.0934
0.245/-0.264
0.0542/0.1186
0.0748/0.1232
0.328/-0.951
-3
˚
)
3
Table 3. Crystallographic Data and Structural Refinement Details of 7-9
7
8
9
chemical formula
crystal size (mm)
formula weight
temperature (K)
radiation
C22H27B10CoO5S2
0.28 ꢀ 0.24 ꢀ 0.22
602.59
C29H35B10Cl2CoO9S2
0.28 ꢀ 0.24 ꢀ 0.23
C22H27B10CoO5S2
0.26 ꢀ 0.22 ꢀ 0.20
602.59
829.62
291(2)
291(2)
291(2)
˚
˚
˚
Mo KR (0.71073 A)
monoclinic
P2(1)/n
Mo KR (0.71073 A)
triclinic
P-1
Mo KR (0.71073 A)
monoclinic
P2(1)/c
crystal system
space group
˚
a (A)
16.357(3)
8.5356(17)
21.208(4)
90.00
106.691(3)
90.00
2836.2(9)
4
1.411
0.786
1232
8.1563(11)
13.1739(18)
18.120(3)
86.919(3)
85.606(2)
85.532(2)
1933.1(5)
2
10.927(2)
14.171(3)
19.382(4)
90.00
102.610(3)
90.00
2928.9(10)
4
1.367
0.761
1232
˚
b (A)
˚
c (A)
R (°)
β (°)
γ (°)
3
˚
V (A )
Z
F
calc (g cm-3
)
1.425
0.739
848
3
absorp. coeff. (mm-1
F(000)
)
θ range (°)
reflns collected
indep. reflns
1.86-26.00
15 060 (Rint = 0.0443)
5564
1.96-26.00
10 734 (Rint = 0.0335)
7460
1.80-26.00
15 587 (Rint = 0.0383)
5680
refns obs. [I >2σ(I)]
data /restr./paras
GOF
3977
5564/0/363
0.978
4873
7460/0/482
1.014
4839
5680/0/363
1.023
R1/wR2I > 2σ(I)]
R1/wR2 (all data)
larg. peak/hole (e A
0.0452/0.1073
0.0726/0.1183
0.310/-0.370
0.0532/0.1010
0.0932/0.1092
0.592/-0.316
0.0474/0.1194
0.0568/0.1234
0.268/-0.603
-3
˚
)
3
1
collection of complexes (2 and 3 and 5-9) are provided in the
Supporting Information (CIF files CCDC 738001, 738000, and
738002-738006) and Tables 2 and 3. Thermal ellipsoids are shown
at the 30% probability level and all hydrogen atoms are omitted for
clarity in ORTEP drawings of 2, 3, and 5-9.
Synthesis of 2 and 3. HCtC-C(O)R (R = Ph (26.0 mg,
0.2 mmol) or 2-naphthyl (36.0 mg, 0.2 mmol)) was added to the
red solution of complex 1 (660 mg, 2 mmol) in CH2Cl2 (20 mL),
and the resultant mixture was stirred for 12 h at ambient
temperature. After removal of solvent, the residue was chromato-
graphed on silica gel. Elution with petroleum ether/CH2Cl2 (2:3)
gave 2 (35.0 mg, 38%) or 3 (35.7 mg, 35%).
2: orange solid, mp 190 °C dec H NMR (CDCl3): δ 5.38
(s, 5H, Cp), 6.47 (d, J = 18 Hz, 1H, B-CHdCH), 7.45 (d, J =
18 Hz, 1H, B-CHdCH), 7.54 (t, 2H, Ph), 7.62 (t, 1H, Ph), 8.04
(d, 2H, Ph). 11B NMR (CDCl3): δ -4.1 (1B), -4.4 (2B), -4.7
(2B), -6.6 (3B), -7.7 (2B). 13C NMR (CDCl3): δ 81.5 (Cp), 97.0
(carborane), 128.7, 128.8, 133.2, 137.3 (Ph), 138.2(B-CHdCH),
140.4 (br, B-CHdCH), 190.1 (CdO). EI-MS (70 eV): m/z 460
(Mþ, 15%). IR (KBr): ν (cm-1) 1638 (CdO), 2579 (B-H). Anal.
calcd for C16H21B10CoOS2: C, 41.73; H, 4.60. Found: C, 41.27;
H, 4.49%.
3: orange solid, mp 203 °C dec 1H NMR (CDCl3): δ 5.37 (s, 5H,
Cp), 6.52 (d, J =18Hz, 1H, B-CHdCH), 7.62 (d, J = 18 Hz, 1H,

Article
Inorganic Chemistry, Vol. 49, No. 8, 2010 3917
B-CHdCH), 7.61-7.66 (2H), 7.91-7.97 (2H), 8.06-8.10 (3H),
8.58 (s, 1H) (2-naphthyl). 11B NMR (CDCl3): δ -6.3 (1B), -6.7
(2B), -6.9 (2B), -8.7 (3B), -9.8 (2B). 13C NMR (CDCl3): δ 81.6
(Cp), 97.0 (carborane), 124.4, 127.0, 127.9, 128.7, 128.8, 129.7,
130.7, 130.9, 132.5, 135.6 (2-naphthyl), 138.2 (B-CHdCH), 140.1
(br, B-CHdCH), 190.1 (CdO). EI-MS (70 eV): m/z 510 (Mþ,
3%). IR (KBr): ν (cm-1) 1648 (CdO), 2577 (B-H). Anal. calcd
for C20H23B10CoOS2: C, 47.05; H, 4.54. Found: C, 46.44; H,
4.71%.
1H, B-CHdCH), 7.59 (t, 2H, Ph), 7.68 (t, 1H, Ph), 8.16 (d, 2H,
Ph). 11B{1H} NMR (CDCl3): δ -0.9 (2B), -2.6 (2B), -3.9 (1B),
-5.4 (3B), -7.1 (2B). 13C NMR(CDCl3): δ 52.7, 52.9 (OCH3),
81.9, 99.5 (carborane), 87.3 (Cp), 119.6 (S-CdC), 128.9, 129.0,
133.7, 137.1 (Ph), 139.1 (B-CHdCH), 140.1 (br, B-CHdCH),
154.9, 171.1, 178.2 (CdO), 189.4 (Co- CdC). EI-MS (70 eV): m/z
602 (Mþ, 10%). IR (KBr): ν (cm-1) 1650, 1709, 1717 (CdO), 2587
(B-H). Anal. calcd for C22H27B10CoO5S2: C, 43.85; H, 4.52.
Found: C, 43.21; H, 4.33%.
8: Red solid, yield 47.7 mg (32%), mp 195 °C dec 1H NMR
(CDCl3): δ 3.24 (s, 3H, OCH3), 3.61 (s, 3H, OCH3), 3.80 (s,
3H, OCH3), 3.94 (s, 3H, OCH3), 5.35 (s, 5H, Cp), 6.72 (d, J =
18.0 Hz, 1H, B-CHdCH), 7.53 (d, J = 18.0 Hz, 1H, B-CHd
CH), 7.48 (t, 2H, Ph), 7.55 (t, 1H, Ph), 8.00 (d, 2H, Ph). 11B{1H}
NMR (CDCl3): δ 4.8 (1B), 2.2 (1B), -0.9 (1B), -4.7 (2B), -7.1
(4B), -10.3 (1B). 13C NMR(CDCl3): δ 52.2, 52.4, 52.8, 53.6
(OCH3), 91.5, 98.6 (carborane), 91.9 (Cp), 102.3 (S-CdC),
128.4, 128.8, 132.4, 138.1 (Ph), 131.7 (S-CdC), 137.1 (B-CHd
CH), 140.4 (br, B-CHdCH), 154.0 (Co-CdC), 162.7, 163.4,
166.2, 175.8, 177.1 (CdO), 187.1 (Co-CdC). ESI-MS (positive
ion mode, m/z): 768.3, [M þ Na]þ. IR (KBr): ν (cm-1) 1665,
1720 (s), 1725, 1746 (CdO), 2591 (B-H). Anal. calcd for
Synthesis of 4-8. General procedure: Alkyne (2 mmol) was
added to the red solution of complex 2 (92.1 mg, 0.2 mmol) in
CH2Cl2 (20 mL), and the resultant mixture was stirred for 12 h at
ambient temperature. After removal of solvent, the residue was
chromatographed on silica gel. Elution with petroleum ether/
CH2Cl2 gave the corresponding product.
1
4: Purple solid, yield 77.6 mg (69%). H NMR (CDCl3): δ
2.03 (d, J = 16.0 Hz, 1H, B-CH2), 2.36 (d, J = 16.0 Hz,
1H, B-CH2), 4.49 (s, 5H, Cp), 7.29 (br s, 5H, Ph), 7.39 (d, J =
18.0 Hz, 1H, B-CHdCH), 7.71 (d, J = 18.0 Hz, 1H,
B-CHdCH), 7.58 (t, 2H, Ph), 7.66 (t, 1H, Ph), 8.12 (d, 2H,
Ph). 11B{1H} NMR (CDCl3): δ -2.5 (1B), -8.9 (1B), -12.0
(2B), -13.9 (5B), -18.5 (1B). 13C NMR(CDCl3): δ 34.3 (br, B-
CH2), 85.3 (Co-C-Ph), 86.6 (Cp), 96.6, 99.5 (carborane), 124.5
(br), 126.3, 129.1, 152.8 (Co-C-Ph), 128.8, 128.9, 133.2, 137.4
(Ph-C(O)), 139.4 (B-CH=CH), 140.1 (br, B-CHdCH),
190.2 (CdO). EI-MS (70 eV): m/z 562 (Mþ, 2%). IR (KBr): ν
(cm-1) 1638 (CdO), 2584 (B-H). Anal. calcd for C24H27B10-
CoOS2: C, 51.23; H, 4.84. Found: C, 50.61; H, 4.89%.
8 CH2Cl2, C29H35B10Cl2CoO9S2: C, 41.98; H, 4.25. Found: C,
3
41.52; H, 4.36.
Synthesis of 9. A red solution of 7 (120.5 mg, 0.2 mmol) in
toluene was heated to 70 °C for 12 h. After removal of solvent,
the residue was chromatographed on silica gel. Elution with
petroleum ether/CH2Cl2 (1:50) gave 9 (92.8 mg, 77%). Red
solid, mp 178 °C dec 1H NMR (CDCl3): δ 3.80 (s, 3H, OCH3),
3.86 (s, 3H, OCH3), 5.43 (s, 5H, Cp), 6.39 (d, J = 18.0 Hz, 1H,
B-CHdCH), 6.79 (s, 1H, B-CdCH), 7.41 (d, J = 18.0 Hz, 1H,
B-CHdCH), 7.53 (t, 2H, Ph), 7.62 (t, 1H, Ph), 8.03 (d, 2H, Ph).
1
5: Red solid, yield 74.4 mg (63%), mp 192 °C dec HNMR
(CDCl3): δ 5.42 (s, 5H, Cp), 6.37 (d, J = 18.0 Hz, 2H,
B-CHdCH), 7.47 (d, J = 18.0 Hz, 2H, B-CHdCH), 7.54 (t,
4H, Ph), 7.63 (t, 2H, Ph), 8.04 (d, 4H, Ph). 11B{1H} NMR
(CDCl3): δ -11.8 (5B), -14.0 (2B), -14.9 (3B). 13CNMR
(CDCl3): δ 81.4 (Cp), 98.4 (carborane), 128.7, 128.8, 133.2,
137.7 (Ph), 138.4 (B-CHd CH), 139.8 (br, B-C HdCH), 190.0
11B{1H} NMR (CDCl3): δ -4.3 (2B), -5.7 (5B), -7.2 (3B). 13
C
NMR(CDCl3):
δ 51.8, 52.3 (OCH3), 81.5 (Cp), 98.7
(carborane), 128.7, 128.8, 133.2, 137.3 (Ph), 138.2 (B-CHd
CH), 140.2 (br, B- C HdCH), 141.1 (B-Cd CH), 166.9, 170.9,
190.1 (CdO). EI-MS (70 eV): m/z 602 (Mþ, 7%). IR (KBr): ν
(cm-1) 1659, 1728 (CdO), 2575 (B-H). Anal. calcd for
C22H27B10CoO5S2: C, 43.85; H, 4.52. Found: C, 43.37; H,
4.24%.
(CdO). EI-MS (70 eV): m/z 590 (Mþ, 4%). IR (KBr): ν (cm-1
)
1617, 1639 (CdO), 2589 (B-H). Anal. calcd for C25H27B10CoO2S2:
C, 50.84; H, 4.61. Found: C, 51.23; H, 4.87%.
1
6: Red solid, yield 71.8 mg (66%), mp 191 °C dec H NMR
(CDCl3): δ 3.77 (s, 3H, OCH3), 5.18 (d, J = 15.0 Hz, 1H, B-CHd
CH), 5.44 (s, 5H, Cp), 6.31 (d, J = 15.0 Hz, 1H, B-CHdCH),
6.51 (d, J = 18.0 Hz, 1H, B-CHdCH), 7.47 (d, J = 18.0 Hz, 1H,
B-CHdCH), 7.54 (t, 2H, Ph), 7.63 (t, 1H, Ph), 8.05 (d, 2H, Ph).
Acknowledgment. We thank the National Science Founda-
tion of China (20925104, 20771055, 90713023, 20721002), the
Major State Basic Research Development Program of China
(2006CB806104), the National Basic Research Program of
China (2007CB925101, 2010CB923303), and the NSFC-RFBR
joint grant (20911120057, 09-03-92216) for financial support of
this work.
11B{1H} NMR (CDCl3): δ -6.5 (4B), -7.3 (3B), -9.9 (3B). 13
C
NMR (CDCl3): δ 51.1 (OCH3), 81.5 (Cp), 97.9 (carborane), 128.8,
133.3, 137.3 (Ph), 134.4 (B-CHdCHCO2Me), 134.8 (br, B-C
HdCHCO2Me), 137.9 (B-CHdCHC(O)Ph), 140.6 (br, B-CHd
CHC(O)Ph), 166.8, 190.1 (CdO). EI-MS (70 eV): m/z 544 (Mþ,
1%). IR (KBr): ν (cm-1) 1629, 1645 (CdO), 2579 (B-H). Anal.
calcd for 6 0.5H2O, C20H26B10CoO3.5S2: C, 43.39; H, 4.73. Found:
3
Supporting Information Available: CIF files giving X-ray
crystallographic data for the structure determinations of com-
pounds 2, 3, and 5-9. This material is available free of charge
via the Internet at http://pubs.acs.org.
C, 43.01; H, 4.52%.
7: Purple solid, yield 61.5 mg (51%), mp 189 °C dec 1H NMR
(CDCl3): δ 3.81 (s, 3H, OCH3), 4.00 (s, 3H, OCH3), 5.34 (s, 5H,
Cp), 7.68 (d, J = 18.0 Hz, 1H, B-CHdCH), 7.91 (d, J = 18.0 Hz,