Pyrrolylmethyl functionalized o-carborane derivatives

Article abstract of DOI:10.1021/acs.organomet.6b00082

The reactions of the 16e half-sandwich complex CpCoS₂C₂B₁₀H₁₀ (1), diazo esters, and various 1,6-diynes (3a-i; PhN(CH₂C CH)₂, 4-Me-PhN(CH₂C CH)₂, 4-OMe-PhN(CH₂C CH)₂, 4-F-PhN(CH₂C CH)₂, BzN(CH₂C CH)₂, O(CH₂C CH)₂, C(Ac)₂(CH₂C CH)₂, N(CH₂C CH)₃, NH(CH₂C CH)N(CH₂C CH)₂) were investigated, in which two novel types of B-H activated products CpCoS₂B₁₀H₉(CH₂CO₂Et)C₅H₃N(R)(CHCHCO₂Et) (4a-c; R = Ph, 4-Me-Ph, 4-OMe-Ph) and the key intermediate CpCoS₂B₁₀H₉(CHCO₂Me) (CH₂CO₂Me) (9) were isolated. 9 features a reactive Co-B bond, which triggers insertion of various 1,6-diynes to further lead to different final products. Substrates 3a-c are activated by the Co-B bond to produce o-carborane derivatives 4a-c which are functionalized by a cobalt-complexed ³-pyrrolylmethyl group. The pyrrole ring is formed by in situ ring closure of 1,6-diynes. Control experiments and isolation of the intermediate CpCoS₂B₁₀H₉(CHCO₂Me)(CH₂CO₂Me)HCC CH₂N(4-Me-Ph)(CH₂C CH) (10) support the proposed mechanism concerning the formation of 4a-c analogues by oxidation. All of the new complexes were characterized by NMR, IR, elemental analysis, and mass spectrometry. The structures of 4a-6a and 9 were determined by single-crystal X-ray diffraction analysis as well.

Full text of DOI:10.1021/acs.organomet.6b00082

Article
pubs.acs.org/Organometallics
Pyrrolylmethyl Functionalized o‑Carborane Derivatives
Huimin Dai, Guifeng Liu, Xiaolei Zhang, Hong Yan,* and Changsheng Lu*
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing,
Jiangsu 210023, People’s Republic of China
S
* Supporting Information
ABSTRACT: The reactions of the 16e half-sandwich complex
CpCoS2C2B10H10 (1), diazo esters, and various 1,6-diynes (3a−
i; PhN(CH2CCH)2, 4-Me-PhN(CH2CCH)2, 4-OMe-
PhN(CH2CCH)2, 4-F-PhN(CH2CCH)2, BzN(CH2C
CH)2, O(CH2CCH)2, C(Ac)2(CH2CCH)2, N(CH2C
CH)3, NH(CH2CCH)N(CH2CCH)2) were investigated,
in which two novel types of B−H activated products
CpCoS2B10H9(CH2CO2Et)C5H3N(R)(CHCHCO2Et) (4a−
c; R = Ph, 4-Me-Ph, 4-OMe-Ph) and the key intermediate CpCoS2B10H9(CHCO2Me) (CH2CO2Me) (9) were isolated. 9
features a reactive Co−B bond, which triggers insertion of various 1,6-diynes to further lead to different final products. Substrates
3a−c are activated by the Co−B bond to produce o-carborane derivatives 4a−c which are functionalized by a cobalt-complexed
η3-pyrrolylmethyl group. The pyrrole ring is formed by in situ ring closure of 1,6-diynes. Control experiments and isolation of the
intermediate CpCoS2B10H9(CHCO2Me)(CH2CO2Me)HCCCH2N(4-Me-Ph)(CH2CCH) (10) support the proposed
mechanism concerning the formation of 4a−c analogues by oxidation. All of the new complexes were characterized by NMR, IR,
elemental analysis, and mass spectrometry. The structures of 4a−6a and 9 were determined by single-crystal X-ray diffraction
analysis as well.
Scheme 1. Three-Component Reactions of (a) 1, Dithioic
Acid, and Methyl Propiolate Leading to A and (b) 1, Ethyl
Diazoacetate (EDA), and Ethynylferrocene Leading to B
INTRODUCTION
■
Due to their unique structural rigidity, chemical stability, and
three-dimensional aromaticity, icosahedral carboranes and their
derivatives have attracted much attention to expand their
applications in versatile fields such as supramolecular chemistry,
functional materials, catalysis, and pharmaceutical research.1−5
In terms of chemical functionalization of carboranes, selective
and straightforward B−H activation6 has been proved
challenging in comparison with the facile modification of the
C−H vertexes of carborane cages.7 Fortunately, significant
advances have been achieved by using transition-metal-
catalyzed or -promoted B−H activation and sequential
modification to form boron−heteroatom bonds.8 During the
past decade, our group has focused on the stoichiometric B−H
activation of the type of half-sandwich transition-metal
complexes Cp′ME2C2B10H10 (Cp′ = Cp, Cp*, M = Co, Rh,
Ir, E = S, Se). Various boron-substituted carboranyl species
have been isolated and fully characterized. Moreover,
mechanisms behind the transformations have been investigated
as well.9−13
Recently three-component reactions, in which a third reagent
is introduced into the reaction of the o-carboranyl dithiolato
half-sandwich compound CpCoS2C2B10H10 (1) with an alkyne,
have led to unusual B−H functionalized carboranyl species
which cannot be obtained by conventional methods. For
example, the presence of an organic 3e− donor (e.g., dithioic
acid) in the reaction of 1 with methyl propiolate has induced
facile B−C coupling between the carboranyl unit and the
cyclopentadienyl ring (Scheme 1a).14 By introduction of a
diazo compound into the reaction mixture of 1 and an alkyne, a
species resulting from alkyne insertion into a Co−B bond could
be isolated (Scheme 1b).15 Inspired by the interesting
chemistry observed in this approach, we are curious about
the probability of intramolecular domino transformations as
well as B−H functionalization by incorporating a substrate with
multiple functional groups. Diynes have been taken into
consideration, as they have shown differing reactivity in
macromolecule synthesis and ring-backbone formation.16 The
introduction of diynes into our three-component reactions
Special Issue: Organometallics in Asia
Received: January 31, 2016
© XXXX American Chemical Society
A
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might produce more versatile functionalization at the boron
sites of o-carborane cage and realize domino ring formation.
Herein, we report a three-component reaction among 1, a diazo
compound, and a 1,6-diyne, which led to the isolation of an
unprecedented carborane species. This carborane species is
B(3) functionalized by a cobalt-complexed η3-pyrrolylmethyl
group. In addition, isolation and characterization of the key
intermediate 9 bearing a reactive Co−B bond support the
alkyne insertion step in B−C bond formation. Finally, a
plausible oxidation mechanism concerning the formation of
those pyrrolylmethyl functionalized o-carborane derivatives has
also been proposed on the basis of control experiments.
Figure 1. Crystal structure of 4a. Ellipsoids are shown at the 30%
probability level, and the hydrogen atoms have been omitted for
clarity. Selected bond lengths (Å): Co(1)−C(7) 2.053(3), Co(1)−
C(8) 2.071(3), Co(1)−C(9) 2.149(3), C(1)−C(2) 1.833(4), B(3)−
C(7) 1.563(5), C(7)−C(8) 1.426(4), N(1)−C(9) 1.399(3), N(1)−
C(10) 1.352(3), C(8)−C(9) 1.425(3), C(8)−C(11) 1.453(4),
C(10)−C(11) 1.373(4).
RESULTS AND DISCUSSION
■
Three-Component Reactions of 1, EDA (2a), and
Aryldipropargylamines 3a−c. In our previous studies,
reactions of 1 with an alkyne and another small organic
molecule such as a thiol, allene, or diazo compound have been
investigated, where cyclopentadienyl or alkenyl functionaliza-
tion at the B(3/6) position of the o-carborane cage were
achieved. Evidently, this is a feasible method to selectively
activate a B−H bond and construct a B−C linkage in carborane
chemistry. However, it remains unknown whether or not this
approach could lead to any new functionalization of B−H
bonds. Thus, the 1,6-diyne 3a, which features two propargyl
groups fixed at one phenyl nitrogen, was selected for the three-
component reaction. Compounds 3a and 2a were added
sequentially to a CH2Cl2 solution of 1 at room temperature,
and the reaction mixture was stirred for 5 h under oxygen,
which led to the isolation of the new complexes 4a (27%), 5a
(25%), and 6a (30%) (Scheme 2). The last two were
somehow activated the C8−C9 double bond but still keeps this
bond shorter than single bonds such as C8−C11 (1.453(4) Å)
and C15−C16 (1.471(7) Å). The C7−C8 (1.426(4) Å) bond
is almost as long as C8−C9 due to the allylic coordination. As
indicated by the largest deviation of atoms to the plane (0.0138
Å), the five-membered ring C8C9N1C10C11 was found to
remain planar. Moreover, the N-linked carbon atom of the
phenyl ring is also in the same plane. The bonds N1−C10
(1.352(3) Å) and N1−C9 (1.399(3) Å) are shorter than those
in diyne reactants (around 1.45 Å). Those further support the
pyrrolyl property of the five-membered ring C8C9N1C10C11.
Two molecules of the diazo ester are involved in the formation
of 4a: one is used to generate a pyrrole-conjugated E-type
alkene, and the other is connected to one sulfur atom to give
rise to a sulfide. B−H bond activation has occurred at the B(3)
position of the carboranyl unit to generate the five-membered
ring Co1S2C2B3C7 in 4a with a B−C bond length of 1.563(5)
Å, which is comparable to the usual B−C bond length (1.55−
1.58 Å) in B-functionalized complexes.17 The five atoms B3,
C2, S2, Co1, and C7 are almost in the same plane with the
largest deviation of 0.0578 Å. The C−C bond of the carborane
cage is lengthened to 1.833(4) Å, longer than that in 1 (1.64
Å).17
Scheme 2. Three-Component Reactions of 1, EDA (2a), and
Aryldipropargylamines 3a−c Leading to B−H
Functionalized Carboranyl Complexes 4a−c, 5a−c, and 6a−
c
The NMR data of complex 4a are consistent with the X-ray
structural analysis. 13C NMR signals of C8 and C9 are located
at 99.16 and 89.38 ppm, respectively, shifted to high field in
comparison to C10 and C11 (131.18 and 122.79 ppm), but still
at much lower field than C7 (a broad peak at 37.57 ppm). In
the 1H NMR spectrum, signals of the two hydrogens at C9 and
C10 appear at 6.70 and 7.91 ppm, respectively, whereas the
hydrogen at C7 appears at 5.84 ppm. All of the NMR data
above suggest that the group C8C9N1C10C11 features a five-
membered pyrrole ring and C7C8C9 adopts an allylic model to
coordinate to the cobalt center. Two doublets with a 16 Hz
coupling constant indicate the E-type configuration of the
alkenyl unit linked to the pyrrole ring. The 11B signal of B(3)
(7.0 ppm) is shifted ca. 4 ppm to low field in comparison with
that in 1, indicating the activation of the B(3)−H bond.
Complex 4a is unique. Both the ring closure and B(3)
functionalization are interesting. Most likely, the pyrrole ring
and B(3)−H functionalization in 4a are generated by domino
reactions with the assistance of the cobalt center. In order not
only to explore the possible mechanism behind the formation
of 4a but also to extend the scope of this ring closure chemistry
in selective functionalization of the carborane cage, 1,6-diynes
characterized as structural analogues generated from the
three-component reaction of 1, 2a, and monoalkynes.13 All of
these complexes (4a−6a) have been characterized by a
combination of X-ray diffraction analysis and spectroscopic
methods.
The crystal structure of 4a (Figure 1) demonstrates that a
five-membered pyrrole ring was generated, which binds with
the cobalt center via allylic coordination (4e donor) to furnish
18e, as indicated by electron-counting rules. In fact, the Co-
coordinated double bond (C8−C9, 1.425(3) Å) in the pyrrole
ring is 0.05 Å longer than that of the noncoordinated bond
(C10−C11, 1.373(4) Å). Therefore, the coordination has
B
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3b−i have been introduced to the three-component reactions
with the consideration of electronic and steric effects as well as
the bridging atoms. When 3b,c were used, each of which
contains an electron-donating group at the para position of the
arylamine, complexes 4b,c were isolated and characterized as
the structural analogues of 4a in similar yields (32% and 35%,
respectively) (Scheme 2). Note that 1,6-diynes with an
electron-donating group at the phenyl ring favor the ring
formation. NMR data of the core frameworks of complexes
4a−c are parallel, as shown in Table 1, from which a rational
conclusion could be drawn that 4b,c are the analogues of 4a.
two of the alkynyl groups as seen in 4a−c. However, a different
type of ring closure takes place at the less sterically hindered
alkynyl group. The crystal structure of 7i features a B-
functionalized product by B(3)−H activation as well, and the
generated B−C bond length is 1.578(4) Å, within the normal
range (1.55−1.58 Å) for B-functionalized complexes. As
illustrated in Figure 2, an imine group has formed between
Table 1. Selected NMR Data (in ppm) for 4a−c
1H NMR
13C NMR
B−CH
Co−CH−N
B−CH
Co−CH−N
Co−C−CH
4a
4b
4c
5.84
5.86
5.86
6.70
6.69
6.66
37.73
37.54
37.35
89.38
89.56
90.02
99.08
98.71
98.79
However, except for 3b,c, all the other examined 1,6-diynes
(3d−i) failed to form 4a analogues (Scheme 3). Substrate 3d,
Figure 2. Crystal structure of 7i. Ellipsoids are shown at the 30%
probability level, and the hydrogen atoms have been omitted for
clarity. Selected bond lengths (Å): Co(1)−N(1) 1.972(2), Co(1)−
C(3) 2.026(3), C(1)−C(2) 1.798(5), C(3)−B(3) 1.578(4), C(5)−
N(1) 1.291(4).
Scheme 3. Three-Component Reactions of 1, EDA (2a), and
Alkynes 3d−i Leading to Complexes 5d−h, 6d, and 7i
C5 and N1 (C5−N1 1.291(4) Å, shorter than a C−N single
bond of around 1.45 Å). The imine group strongly favors
coordinating complexation with the cobalt center to form a
five-membered metallacycle. The NMR data of 7i support the
crystal structure. Signals of the imine group appear at 8.40 ppm
1
in H NMR and 152.34 ppm in 13C NMR, respectively. The
signal of C3 exhibits a broad peak at 28.60 ppm in 13C NMR
due to its connection to the boron atom. The signal of B3 is
shifted to lower field to 11.5 ppm in comparison with that in 1.
Even though all of the introduced substrates containing either
two or three alkynyl groups have led to functionalization of the
o-carborane cage, their reactivities are different. Only 3a−c
reveal the transformation of both alkynyl groups; the others
exhibit the reactivity of monoalkynes. The reactivity differences
of the tested alkynes as well as the in situ ring formation of 4a−
c inspired us to investigate the formation mechanism.
In an attempt to elucidate the mechanism behind the
generation of 4a, control experiments have been performed.
The intermediate 8,11,18 generated from the stoichiometric
reaction between 1 and 2a, was found not able to react with 3b
even in boiling toluene. This demonstrates the necessity of a
second diazo acetate to drive the three-component reaction.
This was further experimentally confirmed by the fact that the
addition of methyl diazoacetate (MDA) to a mixture of 8 and
3b led to a hypo dispersion (1:1 by 1H NMR, Figure S1 in the
Supporting Information) of the 6b analogues 6b-Et-Me and
6b-Me-Et, as shown in Scheme 4. Afterward, B−H activation at
the B(3) site of the o-carboranyl unit takes place upon the Co−
S insertion of both diazo esters to generate a Co−B bond.
To our delight, intermediate 9 (Scheme 5) was isolated and
fully characterized by a combination of NMR spectroscopy and
single crystal X-ray analysis. The crystal structure indicates a
Co−B bond length (1.944(2) Å) (Figure 3) comparable to the
reported data (1.91−2.01 Å).11,19 11B{1H} NMR and 11B NMR
indicate the signal of Co−B to be at −3.7 ppm, which is
significantly shifted to high field in comparison with B(3)−H
which bears a fluoro group at the phenyl ring, gave rise to 5d
and 6d in moderate yields. Substrate 3e, with a benzoyl group
at the bridging nitrogen, could only generate 5e in good yield
(72%). In addition, the reactivity of 3f−h, which possess
different bridging atoms in connecting to the two propargyl
groups, is similar to that of 3e. However, the triyne 3i has
shown reactivity totally different from that of the above
substrates. Despite the existence of three alkynyl groups in 3i,
the reaction does not lead to the expected ring closure of any
C
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presence of an oxygen atmosphere at room temperature,
indicating the importance of oxygen oxidation in pyrrole ring
construction.
Scheme 4. Preparation of 6b Analogues by 8, Methyl
Diazoacetate (MDA), and 3b
On the basis of the above experimental results, a plausible
mechanism for the formation of 4a analogues is summarized in
Scheme 6. After two diazo compounds insert into the Co−S
Scheme 6. Proposed Mechanism for the Generation of
Complexes 4a−c
Scheme 5. Isolation of Intermediates 9 and 10 from the
Three-Component Reaction of 1, MDA, and 3b
bond of 1, intermediate I is generated prior to B−H bond
activation and subsequent Co−B bond formation affords 9.
Then alkyne insertion into the Co−B bond gives rise to 10 with
the terminal alkynyl carbon selectively bonding with the boron
atom. The formation of 10 is followed by two probable
pathways of kinetic transformations dependent on the presence
of oxygen: (1) oxidization to the imine-type intermediate II
under oxygen20 and (2) direct conversion to form the
analogues of 5a and 6a in a nonoxidation procedure. Oxidation
species II is proposed, and it is in equilibrium with species III,
where the cobalt center bears a Fisher carbene and a thiolato
ligand.21 By metal carbene−alkyne metathesis,22 the inter-
mediate IV having one metallic six-membered ring is generated.
Then subsequent carbon nucleophile insertion into the metal
carbene gives rise to V.23 Driven by the macrocycle tension
release and conjugation stabilization in V, the pyrrole group is
formed in VI by the release of H+ and a double bond shift.
Finally, one double bond in the pyrrole ring coordinates to
cobalt to produce analogues 4a−c.
Figure 3. Crystal structure of intermediate 9. Ellipsoids are shown at
the 30% probability level, and the hydrogen atoms have been omitted
for clarity. Selected bond lengths (Å): Co(1)−B(3) 1.944(2), Co(1)−
C(3) 2.007(2), Co(1)−S(1) 2.240(6), C(1)−C(2) 1.691(3).
and B(3)−C bonds. Complex 9 is thermodynamically stable.
However, the green intermediate 10 was immediately observed
upon the addition of 3b to a CH2Cl2 solution of 9 at 0 °C. A
quick detection of the reaction mixture by 1H NMR (Figure S2
in the Supporting Information) and HRMS-ESI (positive
charge mode, m/z 682.2279) led to the identification of
compound 10 as a product of alkyne insertion into the Co−B
bond (Scheme 5). Compound 10 is kinetically stable and is
readily converted to thermodynamically stable products (the
analogues of 5b and 6b) at room temperature even under
argon. In addition, analogues of 4a−c were generated in the
CONCLUSION
■
The three-component reactions of o-carboranyl dichalcogen
complexes 1, diazo esters, and various diynes 3a−i were
investigated. All of the selected alkynes can lead to B(3)−H
activation and functionalization, but the type of products
depends on the alkynes. In particular, the bridging atom
D
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73.86 (CCH); 79.30 (CCH); 88.63 (Cp); 92.68, 110.05 (carborane
C); 113.50 (Co−C−CH2); 117.80, 120.60, 129.08, 148.35 (Ph);
168.22, 174.30 (CO). 11B{1H} NMR (CDCl3): 5.6 (B−CH, 1B),
2.2 (1B), −3.4 (2B), −6.8 (3B), −9.4 (1B), −11.3 (2B). IR (KBr): ν
(cm−1) 1700, 1734 (CO); 2562 (B−H). MS-ESI for (M + Na+):
694.10. Anal. Calcd for C27H38B10CoNO4S2: C, 48.27; H, 5.70. Found:
C, 48.02; H, 5.89. The molecular structure is given in Figure 4.
between the two alkynyl groups of the diynes plays a key role in
determining the structure of the products. Diynes 3a−c without
electron-withdrawing groups in aniline could give rise to the
new-type carborane species 4a−c in which B(3) functionaliza-
tion by a cobalt-complexed η3-pyrrolylmethyl group was
achieved. Other diynes 3d−i functionalize as monoalkynes.
The intermediate 9 containing a reactive Co−B bond and the
intermediate 10 showing alkyne insertion into a Co−B bond
provide key evidence for mechanistic studies of the generation
of novel products 4a−c containing ring closure. Here these
results provide a new pathway to the generation of complicated
carborane functionalized products.
EXPERIMENTAL SECTION
■
All reactions were performed without moisture using standard Schlenk
techniques. Solvents were dehadrated by refluxing over calcium
hydride (dichloromethane) under nitrogen and then distilled prior to
use. All of the reactants were prepared according to the literature
methods. NMR data were recorded on Bruker 400, 500, and 600 MHz
Figure 4. Molecular structure of 5a. Ellipsoids are shown at the 30%
probability level, and hydrogen atoms have been omitted for clarity.
Selected bond lengths (Å): C(7)−B(3) 1.570(4), Co(1)−C(7)
2.085(3), Co(1)−C(8) 2.029(3), Co(1)−C(9) 2.059(3), C(1)−
C(2) 1.825(3).
1
spectrometers. H NMR and 13C NMR spectra were reported in ppm
with respect to residual chloroform (δ(1H) 7.27 ppm and δ(13C) 77.00
ppm), and 11B NMR spectra were reported in ppm with respect to
external Et2O·BF3 (δ(11B) 0.0 ppm). The MS-ESI mass spectra were
recorded on a Finnigan MAT TSQ7000 instrument, and HRMS-ESI
high-resolution mass spectra were measured on an Agilent-G6540
UHD Accurate-MassQ-TOF instrument. IR spectra were measured
with KBr pellets on a Bruker Vector 22 spectrophotometer in the
region 4000−400 cm−1. Elemental analyses were performed with an
Elementar Vario EL III elemental analyzer.
General Procedure for the Preparation of B(3)-Function-
alized Carborane Complexes 4a−7i. Compounds 3a−i (1.2
mmol) and EDA (2a; about 1 mol/L in dichloromethane, 0.21 mL)
were placed dropwise into a Schlenk flask which was charged with 5
mL of a dichloromethane solution of CpCoS2C2B10H10 (1; 330 mg, 1
mmol) at room temperature under an oxygen atmosphere. The
mixture was stirred for 5 h and then concentrated. The residue was
purified by column chromatography (dichloromethane/ethyl acetate
40/1) to give 4a−c, 5a−h, 6a−d, and 7i.
6a: yield 30%, purple solid. Mp: 161.4−162.3 °C. 1H NMR
(CDCl3): δ 1.29 (t, 3H, J = 7.1 Hz, CH2−CH3); 1.34 (t, 3H, J = 7.1
Hz, CH2−CH3); 2.33 (s, 1H, CCH); 1.81−3.20 (9H, B−H); 3.90 (d,
1H, J = 15.5 Hz, S−CH2); 3.98 (d, 1H, J = 15.5 Hz, S−CH2); 4.10−
4.30 (6H, CH2−CCH, CO−CH2); 4.52 (d, 1H, J = 19.0 Hz, CH2−
CCH); 4.60 (d, 1H, J = 19.0 Hz, CH2−CCH); 4.93 (s, 5H, Cp);
5.04 (s, 1H, B−CH−Co); 5.96 (s, 1H, CCH); 6.89 (t, J = 7.8 Hz,
1H, Ph); 6.98 (d, J = 7.8 Hz, 2H, Ph); 7.35 (t, J = 7.8 Hz, 2H, Ph). 13C
NMR (CDCl3): 9.13 (br, B−CH−Co); 13.84, 14.08 (CH2−CH3);
38.73 (S−CH2); 41.06 (CH2−CCH); 57.64 (CH2−CCH); 62.03,
63.44 (CH2−CH3); 72.72 (CCH); 79.36 (CCH); 83.13 (Cp); 89.33,
111.47 (carborane C); 112.19 (CCH); 113.49, 118.55, 129.31,
147.70 (Ph); 174.48, 168.21 (CO), 180.86 (CHC). 11B{1H}
NMR (CDCl3): δ 13.6 (B−CH, 1B), 0.7 (1B), −4.2 (3B), −7.1 (4B),
−12.4 (1B). IR (KBr): ν (cm−1) 1632, 1734 (CO), 2552 (B−H).
MS-ESI for (M + Na+): 694.30. Anal. Calcd for C27H38B10CoNO4S2:
C, 48.27; H, 5.70. Found: C, 47.94; H, 5.58. The molecular structure is
given in Figure 5.
4a: yield 27%, brown solid. Mp: 170.5−171.9 °C. 1H NMR
(CDCl3): δ 1.39 (t, 3H, J = 7.1 Hz, CH2−CH3); 1.40 (t, 3H, J = 7.1
Hz, CH2−CH3); 1.48−3.35 (9H, B−H); 4.02 (s, 2H, S−CH2); 4.32
(q, 2H, J = 7.1 Hz, CH2−CH3); 4.34 (q, 2H, J = 7.1 Hz, CH2−CH3);
4.52 (s, 5H, Cp); 5.84 (s, 1H, B−CH−Co); 6.39 (d, 1H, J = 16.0 Hz,
CHCH−CO); 6.70 (s, 1H, N−CH−Co); 7.41 (t, 1H, J = 7.7 Hz,
Ph); 7.64 (t, 2H, J = 7.7 Hz, Ph); 7.72 (d, 1H, J = 16.0 Hz, CHCH−
CO); 7.83 (d, J = 7.7 Hz, 2H, Ph); 7.91 (s, 1H, N−CHC). 13C
NMR (CDCl3): 14.17, 14.38 (CH2−CH3); 37.73 (br, B−CH−Co);
39.60 (S−CH2), 60.57, 62.22 (CH2−CH3); 85.95 (Cp); 89.38 (N−
CH−Co); 99.08 (Co−C−CH); 91.16, 108.56 (carborane C); 116.16
(CCH−CO); 122.79 (C−CHCH); 131.18 (N−CHC);
134.84 (CHCH−CO); 118.89, 126.39, 130.43, 138.99 (Ph);
167.35, 168.23 (CO). 11B{1H} NMR (CDCl3): 7.0 (B−CH, 1B),
1.6 (1B), −4.9 (2B), −7.3 (3B), −9.4 (1B), −12.1 (2B). IR (KBr): ν
(cm−1) 1689, 1733 (CO); 2572 (B−H). MS-ESI for (M + Na+):
692.15. Anal. Calcd for C27H36B10CoNO4S2: C, 48.42; H, 5.42. Found:
C, 48.04; H, 5.23.
4b: yield 32%, brown solid. Mp: 178.1−179.5 °C. 1H NMR
(CDCl3): δ: 1.39 (t, J = 7.0 Hz, 3H, CH2−CH3), 1.40 (t, J = 7.0 Hz,
3H, CH2−CH3); 2.47 (s, 3H, Ph−CH3); 1.48−3.35 (9H, B−H); 4.02
(s, 2H, S−CH2); 4.32 (q, J = 7.0 Hz, 2H, CH2−CH3), 4.34 (q, J = 7.0
Hz, 2H, CH2−CH3); 4.50 (s, 5H, Cp); 5.86 (s, 1H, B−CH−Co); 6.37
5a: yield 25%, brown solid. Mp: 172.8−174.1 °C. 1H NMR
(CDCl3): δ 1.37 (t, 3H, J = 7.0 Hz, CH2−CH3); 1.38 (t, 3H, J = 7.0
Hz, CH2−CH3); 2.37 (t, 1H, J = 2.1 Hz, CCH); 1.30−3.20 (9H, B−
H); 3.71 (s, 1H, Co−CH−CO); 3.97 (d, 1H, J = 15.5 Hz, S−CH2);
4.02 (d, 1H, J = 15.5 Hz, S−CH2); 3.93 (d, 1H, J = 13.6 Hz, CH2−C−
Co); 5.37 (d, 1H, J = 13.6 Hz, CH2−C−Co); 4.22−4.34 (4H, CH2−
CH3); 4.18 (d, 1H, J = 2.1, 18.0 Hz, CH2−CCH); 4.34 (d, 1H, J = 2.1,
18.0 Hz, CH2−CCH); 4.88 (s, 1H, B−CH−Co); 5.11 (s, 5H, Cp);
6.94 (t, 1H, J = 7.8 Hz, Ph); 7.16 (d, 2H, J = 7.8 Hz, Ph), 7.31 (t, 2H, J
= 7.8 Hz, Ph). 13C NMR (CDCl3): 14.12, 14.31 (CH2−CH3); 39.56
(S−CH2); 39.83 (CH2−CCH); 56.79 (CH2−C−Co); 56.82 (Co−
CH−CO); 61.00, 62.31 (CH2−CH3); 61.22 (br, B−CH−Co);
Figure 5. Molecular structure of 6a. Ellipsoids are shown at the 30%
probability level, and hydrogen atoms have been omitted for clarity.
Selected bond lengths (Å): Co(1)−O(3) 1.979(2), Co(1)−C(7)
2.025(3), C(1)−C(2) 1.808(5), B(3)−C(7) 1.571(4).
E
DOI: 10.1021/acs.organomet.6b00082
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(d, 1H, J = 16.0 Hz, CH−CO); 6.69 (s, 1H, Co−CH−N); 7.72 (d,
1H, J = 16.0 Hz, CHCH−CO); 7.43 (d, 2H, J = 8.1 Hz, Ph); 7.71
(d, 2H, J = 8.1 Hz, Ph); 7.89 (s, 1H, N−CHC). 13C NMR (CDCl3):
14.21, 14.42 (CH2−CH3); 20.99 (Ph−CH3); 37.54 (br, B−CH−Co);
39.64 (S−CH2); 60.62, 62.27 (CH2−CH3); 85.93 (Cp); 89.56 (N−
CH−Co); 98.71 (Co−C−CH); 91.10, 108.56 (carborane C); 115.85
(CCH−CO); 122.52 (C−CHCH); 131.41 (N−CHC);
134.99 (CHCH−CO); 118.88, 130.95, 136.74, 136.47 (Ph);
167.51, 168.34 (CO). 11B{1H} NMR (CDCl3): 7.4 (B−CH, 1B),
1.9 (1B), −3.3 (2B), −7.3 (3B), −9.4 (1B), −12.0 (2B). IR (KBr): ν
(cm−1) 1701, 1732 (CO); 2574 (B−H). MS-ESI for (M + Na+):
706.01. Anal. Calcd for C28H38B10NO4S2Co: C, 49.18; H, 5.60. Found:
C, 49.01; H, 5.72.
CH2−CH3); 2.38 (t, J = 2.3 Hz, 1H, CCH); 1.50−3.20 (9H, B−H);
3.67 (s, 1H, Co−CH−CO); 3.79 (s, 3H, OCH3); 3.78 (d, J = 13.1
Hz, 1H, CH2−C−Co); 5.30 (d, J = 13.1 Hz, 1H, CH2−C−Co); 3.98
(d, J = 15.5 Hz, 1H, S−CH2); 4.03 (d, J = 15.5 Hz, 1H, S−CH2); 4.06
(dd, J = 2.3, 17.5 Hz, 1H, CH2−CCH); 4.29 (dd, J = 2.3, 17.5 Hz, 1H,
CH2−CCH); 4.21 (q, J = 7.0 Hz, 2H, CO−CH2); 4.32 (q, J = 7.0 Hz,
2H, CO−CH2); 4.83 (s, 1H, B−CH−Co); 5.09 (s, 5H, Cp); 6.87 (d, J
= 9.0 Hz, 2H, Ph); 7.14 (d, J = 9.0 Hz, 2H, Ph). 13C NMR (CDCl3): δ
14.18, 14.30 (CH2−CH3); 39.66 (S−CH2); 40.88 (CH2−CCH); 55.56
(Ph−OCH3); 57.25 (Co−CH−CO); 58.06 (CH2−C−Co); 61.40
(br, B−CH−Co); 61.00, 62.36 (CH2−CO); 73.89 (CCH); 79.57
(CCH); 88.64 (Cp); 92.77, 110.27 (carborane C); 113.08 (Co−C−
CH2); 114.39, 121.44, 142.71, 154.87 (Ph); 168.29, 174.12 (CO).
11B{1H} NMR (CDCl3): δ 6.0 (B−CH, 1B); 2.6 (1B); −3.0 (2B);
−6.6 (3B); −9.2 (1B); −11.1 (2B). IR (KBr): ν (cm−1) 1730, 1750
(CO); 2582 (B−H). MS-ESI for (M + Na+): 724.01. Anal. Calcd
for C28H40B10NO5S2Co: C, 47.92; H, 5.74. Found: C, 47.79; H, 5.96.
6c: yield 32%, purple solid. Mp: 171.2−172.4 °C. 1H NMR
(CDCl3): δ 1.28 (t, J = 7.1 Hz, 3H, CH2−CH3); 1.34 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.33 (t, J = 2.3 Hz, 1H, CCH); 1.81−3.20 (9H, B−
H); 3.80 (s, 3H, OCH3); 3.89 (d, J = 15.5 Hz, 1H, S−CH2); 3.97 (d, J
= 15.5 Hz, 1H, S−CH2); 4.10−4.29 (6H, CH2−CCH, CO−CH2);
4.41 (d, J = 19.1 Hz, 1H, CHC−CH2); 4.51 (d, J = 19.1 Hz, 1H,
CHC−CH2); 4.90 (s, 5H, Cp); 5.07 (s, 1H, B−CH−Co); 6.01 (s,
1H, CH−CO); 6.93 (d, J = 9.2 Hz, 2H, Ph); 6.98 (d, J = 9.2 Hz,
2H, Ph). 13C NMR (CDCl3): δ 9.44 (br, Co−CH−B); 13.95, 14.17
(CH2−CH3); 38.86 (S−CH2); 42.00 (CH2−CCH); 55.74 (OCH3);
62.32 (CH2−CCH); 62.15, 63.53 (CO−CH2); 72.90 (CCH); 79.56
(CCH); 83.23 (Cp); 89.34, 111.43 (carborane C); 112.47 (CHC);
114.85, 115.95, 142.46, 153.17 (Ph); 168.37, 174.61 (CO); 181.51
(CCH). 11B{1H} NMR (CDCl3): δ 14.6 (B−CH, 1B), 0.8 (1B),
−4.1 (3B), −7.1 (4B), −12.6 (1B). IR (KBr): ν (cm−1) 1730, 1730
(CO); 2577 (B−H). MS-ESI for (M + Na+): 724.19. Anal. Calcd
for C28H40B10NO5S2Co: C, 47.92; H, 5.74. Found: C, 47.67; H, 5.95.
5d: yield 63%, brown solid. Mp: 176.4−177.1 °C. 1H NMR
(CDCl3): δ 1.37 (t, J = 7.1 Hz, 3H, CH2−CH3), 1.38 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.39 (t, J = 2.2 Hz, 1H, CCH); 1.50−3.20 (9H, B−
H); 3.69 (s, 1H, Co−CH−CO); 3.80 (d, J = 13.2 Hz, 1H, CH2−C−
Co); 5.30 (d, J = 13.2 Hz, 1H, CH2−C−Co); 3.98 (d, J = 15.5 Hz, 1H,
S−CH2); 4.03 (d, J = 15.5 Hz, 1H, S−CH2); 4.08 (dd, J = 17.9, 2.2
Hz, 1H, CH2−CCH); 4.20−4.35 (5H, CH2−CCH, CO−CH2); 4.82
(s, 1H, B−CH−Co); 5.10 (s, 5H, Cp); 7.00 (t, J = 8.7 Hz, 2H, Ph);
7.14 (dd, J = 4.6, 9.1 Hz, 2H, Ph). 13C NMR (CDCl3): δ 14.13, 14.28
(CH2−CH3); 39.59 (S−CH2); 40.48 (CH2−CCH); 56.94 (Co−CH−
CO); 57.73 (CH2−C−Co); 61.37 (br, B−CH−Co); 61.02, 62.33
(CO−CH2); 79.10 (CCH); 74.11 (CCH); 88.64 (Cp); 92.79, 110.20
(carborane C); 112.87 (Co−C−CH2); 115.52 (JC−F = 22.2 Hz, Ph);
120.51 (JC−F = 7.7 Hz, Ph); 145.03 (Ph); 157.35 (JC−F = 240.3 Hz,
Ph); 168.20, 174.22 (CO). 11B{1H} NMR (CDCl3): δ 6.1 (B−CH,
1B); 2.5 (1B); −3.2 (2B); −6.6 (3B); −9.2 (1B); −11.0 (2B). IR
(KBr): ν (cm−1) 1730, 1742 (CO); 2567 (B−H). MS-ESI for (M +
Na+): 711.93. Anal. Calcd for C27H37B10NO4FS2Co: C, 47.01; H, 5.41.
Found: C, 46.83; H, 5.32.
5b: yield 24%, brown solid. Mp: 182.3−183.2 °C. 1H NMR
(CDCl3): δ 1.36 (t, J = 7.1 Hz, 3H, CH2−CH3); 1.38 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.30 (s, 3H, Ph−CH3); 2.36 (t, J = 2.3 Hz, 1H,
CCH); 1.30−3.20 (9H, B−H); 3.70 (s, 1H, Co−CH−CO); 3.85
(d, J = 13.4 Hz, 1H, CH2−C−Co); 5.30 (d, J = 13.4 Hz, 1H, CH2−C−
Co); 3.98 (d, J = 15.5 Hz, 1H, S−CH2); 4.03 (d, J = 15.5 Hz, 1H, S−
CH2); 4.12 (dd, J = 2.3, 18.0 Hz, 1H, CH2−CCH); 4.32 (dd, J = 2.3,
18.0 Hz, 1H, CH2−CCH); 4.20−4.28 (m, 2H, CO−CH2); 4.31 (q, J =
7.1 Hz, 2H, CO−CH2); 4.86 (s, 1H, B−CH−Co); 5.10 (s, 5H, Cp);
7.07 (d, J = 8.6 Hz, 2H, Ph); 7.12 (d, J = 8.6 Hz, 2H, Ph). 13C NMR
(CDCl3): δ 14.15, 14.30 (CH2−CH3); 20.49 (Ph−CH3); 39.60 (S−
CH2); 40.05 (CH2−CCH); 57.06 (CH2−C−Co); 57.27 (Co−CH−
CO); 61.69 (br, B−CH−Co); 60.98, 62.32 (CO−CH2); 73.79
(CH2−CCH); 79.41 (CH2−CCH); 88.63 (Cp); 92.72, 110.17
(carborane C); 113.45 (Co−C−CH2); 118.66, 129.60, 130.42,
146.36 (Ph); 168.23, 174.16 (CO). 11B{1H} NMR (CDCl3): 6.1
(B−CH, 1B); 2.6 (1B); −2.9 (2B); −6.6 (3B); −9.2 (1B); −11.1
(2B). IR (KBr): ν (cm−1) 1730, 1734 (CO); 2573 (B−H). MS-ESI
for (M + Na+): 707.98. Anal. Calcd for C28H40B10NO4S2Co: C, 49.04;
H, 5.88. Found: C, 48.77; H, 5.99.
6b: yield 34%, purple solid. Mp: 165.4−167.0 °C. 1H NMR
(CDCl3): δ 1.27 (t, J = 7.1 Hz, 3H, CH2−CH3), 1.34 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.32 (t, J = 2.2 Hz, 1H, CCH); 2.30 (s, 3H, PhCH3);
1.81−3.20 (9H, B−H); 3.89 (d, J = 15.5 Hz, 1H, S−CH2); 3.97 (d, J =
15.5 Hz, 1H, S−CH2); 4.10−4.30 (6H, CH2−CCH, CO−CH2); 4.46
(d, J = 18.7 Hz, 1H, CHCCH2); 4.55 (d, J = 18.7 Hz, 1H, CH
CCH2); 4.92 (s, 5H, Cp); 5.04 (s, 1H, B−CH−Co); 5.98 (s, 1H, CH−
CO); 6.90 (d, J = 8.4 Hz, 2H, Ph); 7.16 (d, J = 8.4 Hz, 2H, Ph). 13C
NMR (CDCl3): δ 13.90, 14.14 (CH2−CH3); 9.20 (br, Co−CH−B);
20.31 (Ph−CH3); 38.82 (S−CH2); 41.29 (CH2−CCH); 57.89 (CH2−
CCH); 62.13, 63.49 (CO−CH2); 72.66 (CCH); 79.49 (CCH);
83.19 (Cp); 89.26, 111.32 (carborane C); 112.26 (CHC); 113.77,
129.88, 127.96, 145.58 (Ph); 174.58, 168.34 (CO); 181.14 (C
CH). 11B{1H} NMR (CDCl3): δ 13.7 (B−CH, 1B); 0.6 (1B); −4.4
(3B); −7.4 (4B); −12.5 (1B). IR (KBr): ν (cm−1) 1699, 1733 (C
O), 2559 (B−H). MS-ESI for (M + Na+): 708.12. Anal. Calcd for
C28H40B10NO4S2Co: C, 49.04; H, 5.88. Found: C, 48.85; H, 5.63.
4c: yield 35%, brown solid. Mp: 181.3−182.2 °C. 1H NMR
(CDCl3): δ 1.38 (t, J = 7.0 Hz, 3H, CH2−CH3), 1.39 (t, J = 7.0 Hz,
3H, CH2−CH3); 1.48−3.35 (9H, B−H); 3.92 (s, 3H, Ph−OCH3);
4.02 (s, 2H, S−CH2); 4.31 (q, J = 7.0 Hz, 2H, CH2−CH3), 4.33 (q, J =
7.0 Hz, 2H, CH2−CH3); 4.50 (s, 5H, Cp); 5.87 (s, 1H, B−CH−Co);
6.36 (d, 1H, J = 16.0 Hz, CH−CO); 6.67 (s, 1H, Co−CH−N); 7.71
(d, 1H, J = 16.0 Hz, CHCH−CO); 7.15 (d, 2H, J = 8.7 Hz, Ph);
7.75 (d, 2H, J = 8.7 Hz, Ph); 7.84 (s, 1H, N−CHC). 13C NMR
(CDCl3): 14.20, 14.42 (CH2−CH3); 37.35 (br, B−CH−Co); 39.63
(S−CH2); 55.73 (Ph−OCH3), 60.60, 62.27 (CH2−CH3); 85.87 (Cp);
90.02 (N−CH−Co); 98.79 (Co−C−CH); 91.10, 108.54 (carborane
C); 115.58 (CCH−CO); 122.32 (C−CHCH); 131.67 (N−
CHC); 135.01 (CHCH−CO); 120.44, 115.58, 132.66, 158.26
(Ph); 167.52, 168.32 (CO). 11B{1H} NMR (CDCl3): 7.5 (B−CH,
1B), 2.1 (1B), −4.0 (2B), −6.9 (3B), −9.3 (1B), −11.5 (2B). IR
(KBr): ν (cm−1) 1689, 1733 (CO); 2572 (B−H). MS-ESI for (M +
Na+): 722.09. Anal. Calcd for C28H38B10NO5S2Co: C, 48.06; H, 5.47.
Found: C, 47.81; H, 5.39.
6d: yield 21%, purple solid. Mp: 159.6−160.6 °C. 1H NMR
(CDCl3): δ 1.28 (t, J = 7.1 Hz, 3H, CH2−CH3), 1.34 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.35 (t, J = 2.3 Hz, 1H, CCH); 1.51−3.20 (9H, B−
H); 3.89 (d, J = 15.5 Hz, 1H, S−CH2); 3.97 (d, J = 15.5 Hz, 1H, S−
CH2); 4.13−4.29 (6H, CH2−CCH, CO−CH2); 4.44 (d, J = 19.6 Hz,
1H, CHCCH2); 4.54 (d, J = 19.6 Hz, 1H, CHCCH2); 4.92 (s,
5H, Cp); 5.03 (s, 1H, B−CH−Co); 5.96 (s, 1H, CH−CO); 6.93
(dd, J = 4.3, 9.2 Hz, 2H, Ph), 7.05 (t, J = 8.8 Hz, 2H, Ph). 13C NMR
(CDCl3): 9.29 (br, Co−CH−B); 13.89, 14.13 (CH2−CH3); 38.82
(S−CH2); 41.63 (CH2−CCH); 58.23 (CH2−C−Co); 62.14, 63.58
(CO−CH2); 73.01 (CCH); 79.14 (CCH); 83.16 (Cp); 89.30, 110.40
(carborane C); 112.25 (CHC); 115.10 (JC−F = 7.7 Hz, Ph); 115.88
(JC−F = 22.2 Hz, Ph); 144.47 (Ph); 157.53 (JC−F = 240.3, Ph); 168.31,
174.48 (CO); 180.88 (CCH). 11B{1H} NMR (CDCl3): δ 13.9
(B−CH, 1B), 0.7 (2B), −4.4 (3B), −7.3 (3B), −12.5 (2B). IR (KBr):
ν (cm−1) 1733, 1635 (CO); 2582 (B−H). MS-ESI for (M + Na+):
5c: yield 27%, brown solid. Mp: 184.2−185.3 °C. 1H NMR
(CDCl3): δ 1.35 (t, J = 7.0 Hz, 3H, CH2−CH3); 1.38 (t, 7.0 Hz, 3H,
F
DOI: 10.1021/acs.organomet.6b00082
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
712.08. Anal. Calcd for C27H37B10NO4FS2Co: C, 47.01; H, 5.41.
Found: C, 46.77; H, 5.63.
7i: yield 62%, brown solid. Mp: 169−170.1 °C. 1H NMR (CDCl3):
δ 1.33 (t, 3H, J = 7.1 Hz, CH2−CH3); 1.34 (t, 3H, J = 7.1 Hz, CH2−
CH3); 2.45 (t, 2H, J = 2.2 Hz, CCH); 1.31−3.10 (9H, B−H); 3.87 (s,
2H, S−CH2); 4.19 (q, 2H, J = 7.1 Hz, CH2−CH3); 4.27 (q, 2H, J = 7.1
Hz, CH2−CH3); 4.43 (dd, 2H, J = 17.9, 2.2 Hz,CH2−CCH); 5.32 (dd,
2H, J = 17.9, 2.2 Hz,CH2−CCH); 4.95 (s, 5H, Cp); 5.22 (s, 1H, B−
CH−Co); 6.16 (s, 1H, CCH); 8.40 (s, 1H, NCH). 13C NMR
(CDCl3): δ 14.09, 14.26 (CH2−CH3); 28.60 (br, B−CH−Co); 38.78
(S−CH2); 42.85 (CH2−CCH); 60.15, 62.02 (CH2−CH3); 75.37
(CCH); 76.14 (CCH); 85.51 (Cp); 83.10, 109.42 (carborane C);
89.43 (CCH); 111.48 (CCH); 152.34 (NCH); 166.30, 168.21
(CO). 11B{1H} NMR (CDCl3): δ 11.5 (B−CH, 1B), 0.2 (1B), −4.9
(3B), −7.0 (4B), −12.5 (1B). IR (KBr): ν (cm−1) 1689, 1735 (C
O), 2555 (B−H). MS-ESI for (M + Na+): 669.15. Anal. Calcd for
C24H35B10CoN2O4S2: C, 44.57; H, 5.45. Found: C, 44.22; H, 5.67.
Isolation of Intermediate 9. MDA (about 1 mol/L in
dichloromethane, 0.2 mL) was added dropwise to a dichloromethane
solution of 1 (33.0 mg, 0.1 mmol) at room temperature under an
oxygen atmosphere. The mixture was stirred for 1 h and separated by
chromatography (dichloromethane/ethyl acetate 40/1) to give 9 in
89% yield. 9 could be recrystallized from dichloromethane and
petroleum ether. Yellow solid. Mp: 157.3−157.9 °C. 1H NMR
(CDCl3): δ 1.56−3.27 (9H, BH); 3.74 (d, J = 16.2 Hz, 1H, S−CH2);
4.63 (d, J = 16.2 Hz, 1H, S−CH2); 3.75 (s, 3H, OCH3); 3.78 (s, 3H,
OCH3); 4.87 (s, 5H, Cp); 5.28 (s, 1H, S−CH−Co). 13C NMR
(CDCl3): δ 32.90 (S−C−Co); 36.61 (S−CH2); 51.45, 52.99 (O−
CH3); 85.13 (Cp); 93.15, 96.41 (carborane C); 166.46, 181.56 (C
O). 11B{1H} NMR (CDCl3): δ −0.4 (1B), −3.7 (1B, Co−B), −5.0
(2B), −6.0 (2B), −8.7 (2B), −10.9 (1B), −12.6 (1B). IR (KBr): ν
(cm−1) 1739, 1682 (CO); 2558 (B−H). HRMS-ESI for
C13H23B10CoNaO4S2 (M + Na+): calculated, 497.1198; found,
497.1273.
Isolation of Intermediate 10. 3b (36.8 mg, 0.2 mmol) was added
to 5 mL of a dichloromethane solution of intermediate 9 (95.0 mg, 0.2
mmol) under the protection of Ar, and the mixture was stirred at −0
°C for 0.5 h. A green complex was then separated in 91% yield using
preparative TLC. 1H NMR (CDCl3): δ 2.25 (t, 1H, J = 2.2 Hz, CCH);
1.51−3.10 (9H, B−H); 2.28 (s, 3H, Ph−CH3); 3.53 (s, 1H, CH−Co);
3.76 (d, 1H, J = 16.0 Hz, CH2−S); 4.11 (d, 1H, J = 16.0 Hz, CH2−S);
3.82 (s, 3H, O−CH3); 3.87 (s, 3H, O−CH3); 4.05−4.11 (m, 2H,
CH2−CCH); 4.72 (d, 1H, J = 18.0 Hz, CH2−C−Co); 4.83 (d, 1H, J =
18.0 Hz, CH2−C−Co); 4.98 (s, 5H, Cp); 5.66 (s, 1H, CCH−B);
6.73 (d, 2H, J = 8.3 Hz, Ph); 7.09 (d, 2H, J = 8.3 Hz, Ph). HRMS-ESI
for C26H36B10CoNNaO4S2 (M + Na+): calculated, 682.2245, found,
682.2279.
5e: yield 72%, brown solid. Mp: 204.7−205.3 °C. 1H NMR
(CDCl3): δ 1.37 (t, J = 7.0 Hz, 3H, CH2−CH3); 1.42 (t, J = 7.0 Hz,
3H, CH2−CH3); 2.40 (s, J = 1H, CCH); 1.50−3.20 (9H, B−H); 3.90
(1H, CH2−C−Co); 3.97 (d, J = 15.5 Hz, 1H, S−CH2); 4.02 (d, J =
15.5 Hz, 1H, S−CH2); 4.19 (2H, CH2−CCH); 4.26−4.44 (4H, CO−
CH2); 5.17 (5H, Cp); 4.84−5.27 (3H, B−CH−Co, CH2−C−Co);
7.47 (3H, Ph); 7.56 (m, 2H, Ph); 13C NMR (CDCl3): δ 14.16, 14.44
(CH2−CH3); 39.33 (CH2−CCH); 39.58 (S−CH2); 56.76 (CH2−C−
Co); 60.44 (br, B−CH−Co); 61.11, 62.33 (CO−CH2); 73.85 (CCH),
78.37 (CCH); 88.93 (Cp); 93.08, 110.11 (carborane C); 113.99
(CHC); 126.72, 128.72, 130.19, 135.10 (Ph); 171.71 (CO−Ph);
168.14, 174.39 (CO−CH2). 11B{1H} NMR (CDCl3): δ 6.1 (B−CH,
1B), 2.3 (1B), −3.0 (2B), −6.8 (3B), −9.2 (1B), −11.3 (2B). IR
(KBr): ν (cm−1) 1699, 1640 (CO); 2559 (B−H). MS-ESI for (M +
Na+): 722.10. Anal. Calcd for C28H38B10NO5S2Co: C, 48.06; H, 5.47.
Found: C, 47.66; H, 5.69.
5f: yield 94%, brown solid. Mp: 224.1−224.9 °C. 1H NMR-
(CDCl3): δ 1.37 (t, J = 7.1 Hz, 3H, CH2−CH3) 1.41 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.52 (s, 1H, CCH); 1.30−3.20 (9H, B−H); 3.78 (s,
1H, Co−CH−CO); 3.98 (d, J = 15.4 Hz, 1H, S−CH2); 4.03 (d, J =
15.4 Hz, 1H, S−CH2); 4.25−4.35 (5H, CH2−CCH, CO−CH2); 4.43
(d, J = 16.1 Hz, 1H, CH2−CCH); 4.80 (d, J = 13.3 Hz, 1H, CH2−C−
Co); 5.07 (d, J = 13.3 Hz, 1H, CH2−C−Co); 5.08 (s, 5H, Cp); 5.12
(s, 1H, B−CH−Co); 13C NMR (CDCl3): δ 14.16, 14.44 (CH2−CH3);
39.61 (S−CH2); 54.74 (Co−CH−CO); 55.90 (br, B−CH−Co);
57.98 (CH2−CCH); 60.94, 62.31 (CO−CH2); 69.17 (CH2−C−Co);
75.55 (CCH), 79.06 (CCH); 88.59 (Cp); 92.62, 110.08 (carborane
C); 114.99 (Co−C−CH2); 168.25, 174.47 (CO). 11B{1H} NMR
(CDCl3): δ 6.2 (B−CH, 1B), 2.4 (1B), −3.1(2B), −6.7 (3B), −9.2
(1B), −11.2 (2B). IR (KBr): ν (cm−1) 1728, 1661 (CO); 2562 (B−
H). MS-ESI for (M + Na+): 619.01. Anal. Calcd for C21H33B10CoO5S2:
C, 42.27; H, 5.57. Found: C, 42.01; H, 5.69.
5g: yield 79%, brown solid. Mp: 203.5−204.2 °C. 1H NMR
(CDCl3): δ 1.37 (t, J = 7.1 Hz, 3H, CH2−CH3); 1.40 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.19 (t, J = 2.3 Hz, 1H, CCH); 2.21 (s, 3H, CO−
CH3); 2.30 (s, 3H, CO−CH3); 1.50−3.20 (9H, B−H); 2.66 (d, J =
13.5 Hz, 1H, CH2−C−Co); 2.90 (d, J = 18.2 Hz, 1H, CH2−CCH);
3.33 (d, J = 18.2 Hz, 1H, CH2−CCH); 3.59 (s, 1H, Co−CH−CO);
3.98 (d, J = 15.5 Hz, 1H, S−CH2); 4.03 (d, J = 15.5 Hz, 1H, S−CH2);
4.25−4.35 (5H, CH2−C−Co, CO−CH2); 4.85 (s, 1H, B−CH−Co);
5.10 (s, 5H, Cp); 13C NMR (CDCl3): δ 14.06, 14.38 (CH2−CH3);
21.23 (CH2−CCH); 27.45, 27.80 (CO−CH3); 38.89 (S−CH2, CH2−
C−CO); 60.93, 61.98 (CO−CH2); 63.30 (Co−CH−CO); 65.26
(br, B−CH−Co); 71.02 (CO−C−CO); 73.38 (CCH); 79.12 (CCH);
87.95 (Cp); 97.21, 118.26 (carborane C); 113.94 (Co−C−CH2);
167.26, 174.09 (CH2−CO); 203.57, 204.00 (CH3−CO). 11B{1H}
NMR (CDCl3): δ 6.8 (B−CH, 1B), 1.8 (1B), −0.3(1B), −1.6 (1B),
−4.6 (3B), −7.6 (1B), −9.4 (2B). IR (KBr): ν (cm−1) 1789, 1740,
1670 (CO); 2557 (B−H). MS-ESI for (M + Na+): 701.00. Anal.
Calcd for C26H39B10CoO6S2: C, 46.01; H, 5.79. Found: C, 45.78; H,
5.61.
X-ray Crystallography. Crystals suitable for X-ray analysis were
obtained by slow evaporation of a solution in petroleum ether/
dichloromethane. Diffraction data were collected on a Bruker SMART
Apex II CCD diffractometer by means of graphite-monochromated
Mo Kα (λ = 0.71073 Å) radiation. During collection of the intensity
data, no significant decay was observed. The intensities were corrected
for Lorentz−polarization effects and empirical absorption by using the
SADABS program.24 The structures were solved by direct methods
with the SHELXL-97 program.25 All non-hydrogen atoms were found
from the difference Fourier syntheses. The H atoms were included in
calculated positions with isotropic thermal parameters related to those
of the supporting carbon atoms but were not included in the
refinement. All calculations were performed by using the Bruker Smart
program. CCDC files 1444668−1444672 contain supplementary
crystallographic data for this paper. These data can be obtained free
of charge from the Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/datarequest/cif.
5h: yield 84%, brown solid. Mp: 176.3−177.2 °C. 1H NMR
(CDCl3): δ 1.37 (t, J = 7.1 Hz, 3H, CH2−CH3) 1.42 (t, J = 7.1 Hz,
3H, CH2−CH3); 2.32 (t, J = 2.3 Hz, 2H, CCH); 1.50−3.20 (9H, B−
H); 3.12 (d, J = 12.4 Hz, 1H, CH2−C−Co); 4.61 (d, J = 12.4 Hz, 1H,
CH2−C−Co); 3.70 (d, J = 2.3 Hz, 4H, CH2−CCH); 3.77 (s, 1H, Co−
CH−CO); 3.98 (d, J = 15.5 Hz, 1H, S−CH2); 4.03 (d, J = 15.5 Hz,
1H, S−CH2); 4.25−4.35 (4H, CO−CH2); 4.82 (s, 1H, B−CH−Co);
5.08 (s, 5H, Cp). 13C NMR (CDCl3): δ 14.16, 14.39 (CH2−CH3);
39.63 (S−CH2); 42.00 (CH2−CCH); 57.32 (Co−CH−CO); 58.32
(CH2−C−Co); 61.69 (br, B−CH−Co); 60.93, 62.34 (CO−CH2);
73.82 (CCH); 78.70 (CCH); 88.55 (Cp); 92.78, 110.25 (carborane
C); 113.92 (Co−C−CH2); 168.25, 174.18 (CO). 11B{1H} NMR
(CDCl3): δ 5.9 (B−CH, 1B), 2.5 (1B), −3.1 (2B), −6.6 (3B), −9.2
(1B), −11.0 (2B). IR (KBr): ν (cm−1) 1730, 1665 (CO); 2562 (B−
ASSOCIATED CONTENT
■
S
* Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.6b00082.
H). MS-ESI for (M
C24H36B10CoNO4S2: C, 45.49; H, 5.73. Found: C, 45.12; H, 5.87.
+
Na+): 655.98. Anal. Calcd for
G
DOI: 10.1021/acs.organomet.6b00082
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
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Synthesis of 3a−i, details of control experiments, NMR
spectra, and crystallographic data (PDF)
Crystallographic data (CIF)
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AUTHOR INFORMATION
Corresponding Authors
*E-mail for H.Y.: hyan1965@nju.edu.cn.
*E-mail for C.L.: luchsh@nju.edu.cn.
■
118, 1223−1224. (g) Vinas, C.; Benakki, R.; Teixidor, F.; Casabo, J.
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Inorg. Chem. 1995, 34, 3844−3845.
Notes
(8) (a) Mirabelli, M. G. L.; Sneddon, L. G. J. Am. Chem. Soc. 1988,
110, 449−453. (b) Quan, Y.-J.; Xie, Z.-W. J. Am. Chem. Soc. 2014, 136,
15513−15516. (c) Quan, Y.-J.; Xie, Z.-W. J. Am. Chem. Soc. 2015, 137,
3502−3505. (d) Qiu, Z.-Z.; Quan, Y.-J.; Xie, Z.-W. J. Am. Chem. Soc.
2013, 135, 12192−12195. (e) Cao, K.; Huang, Y.-W.; Yang, J.-X.; Wu,
J. Chem. Commun. 2015, 51, 7257−7260. (f) Herberhold, M.; Yan, H.;
Milius, W.; Wrackmeyer, B. Angew. Chem., Int. Ed. 1999, 38, 3689−
3691.
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
This work was supported by the National Natural Science
Foundation of China (21271102, 21472086, and 21531004),
the National Basic Research Program of China
(2013CB922101), the Natural Science Foundation of Jiangsu
Province (BK20130054), and the High Performance Comput-
ing Center of Nanjing University.
(9) For alkyl ketones, see: (a) Li, Y.-G.; Jiang, Q.-B.; Li, Y.-Z.; Yan,
H.; Bregadze, V. I. Inorg. Chem. 2010, 49, 4−6. (b) Wang, Z.-J.; Ye, H.-
D.; Li, Y.-G.; Li, Y.-Z.; Yan, H. J. Am. Chem. Soc. 2013, 135, 11289−
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Inorg. Chem. 2011, 2011, 2763−2768. (d) Li, Y.-G.; Jiang, Q.-B.;
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