Reactivity of the 16-electron CpCo half-sandwich complex containing a B(3,6)-disubstituted o-carborane-1,2-dithiolate ligand

Article abstract of DOI:10.1016/j.jorganchem.2013.03.026

The 16-electron (16e) half-sandwich complex CpCo(S₂C ₂B₁₀H₈)(CHCHCO₂Me)₂ (1; Cp = cyclopentadienyl) was considered as inert owing to hindered di-substitution at B sites. However in methanol complex 1 reacts with ethynylferrocene (FcCCH) and dimethyl acetylenedicarboxylate (DMAD, MeO₂CCCCO₂Me) to lead to two-fold alkyne insertion at Co-S bond to give rise to unusual stable 18e adduct CpCo(S₂C₂B₁₀H₈) (CHCHCO₂Me)₂(HCCFc)(MeO₂CCCCO₂Me) (2) containing mixed alkynes. Also in methanol complex 1 undergoes intramolecular hydrogen transfer of one CHCHCO₂Me unit to adjacent carbon to form a CH₂CCO₂Me unit, thus producing the 18e complex CpCo(S₂C₂B₁₀H₈)[CH ₂CCO₂Me][CHCHCO₂Me] (3). Further investigation indicates that complex 1 can catalyze [2 + 2 + 2] cycloaddition of alkynes. The catalytic efficiency is determined by temperature and nature of alkynes. In THF in the presence of [N(n-Bu)₄]Br complex 1 is transformed to ionic complex [N(n-Bu)₄]⁺[Co(S₂C₂B ₁₀H₈)₂(CHCHCO₂Me)₄] ^- (4), in which metal-dithiolene is planar. Analogous [N(n-Bu) ₄]⁺[Co(S₂C₂B₁₀H ₉)₂(CHCHCO₂Me)₂]^- (5) was also synthesized from mono-substituted precursor CpCo(S₂C ₂B₁₀H₉)(CHCHCO₂Me) (1′). The electrochemical properties of both 4 and 5 show significant positive shift of redox peaks versus the analogous bis(1,2-benzenedithiolato)cobaltate (III) (Co(_bdt)2). Reactivity of both neutral 16e CpCo complexes and ionic metal-dithiolene derivatives declines with the increase of substituents on carborane cage. All the new compounds have been characterized by NMR, IR, mass spectrometry, elemental analysis, and 2, 3, and 4 have been structurally characterized by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2013.03.026

Accepted Manuscript
Reactivity of the 16-Electron CpCo Half-Sandwich Complex Containing a B(3,6)-
Disubstituted o-Carborane-1,2-dithiolate Ligand
Xiao Tang, Zhaojin Wang, Yizhi Li, Hong Yan
PII:
S0022-328X(13)00211-8
10.1016/j.jorganchem.2013.03.026
JOM 17936
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 7 February 2013
Revised Date: 13 March 2013
Accepted Date: 14 March 2013
Please cite this article as: X. Tang, Z. Wang, Y. Li, H. Yan, Reactivity of the 16-Electron CpCo Half-
Sandwich Complex Containing a B(3,6)-Disubstituted o-Carborane-1,2-dithiolate Ligand, Journal of
Organometallic Chemistry (2013), doi: 10.1016/j.jorganchem.2013.03.026.
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ACCEPTED MANUSCRIPT
MeO2C
MeO2C
Co
Co
S
S
MeO2C
CO2Me
S
S
CO2Me
MeO2C Fc
S
Co
S
2
3
Fc
MeO C
CO2Me
+
CO2Me
2
CH3OH / R.T.
CH3OH / R.T.
MeO2C
MeO2C
CO2Me
1
S
S
Co
N(n-Bu)4
S
S
B
C
MeO2C
CO2Me
4
N(n-Bu)4Br
THF / R.T.

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In methanol complex 1 reacts with alkynes to lead to product 2 and isomerizes to 3. In the
presence of [N(n-Bu)4]Br in THF complex 1 can be transformed to ionic square-planar
complex 4 which shows notably different electrochemical properties in contrast to
analogous carborane-free complexes.

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1. CpCo(S2C2B10H8)(CH=CHCO2Me)2 reacts with selected alkynes to give insertion
product.
2. In methanol a Co(III)-mediated H-shift occurs which may occur via a Co−H
agostic bond.
3. The
16e
complex
can
be
transformed
to
[N(n-Bu)4]+[Co(S2C2B10H8)2(CH=CHCO2Me)4]−.

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Reactivity of the 16-Electron CpCo Half-Sandwich Complex Containing a
B(3,6)-Disubstituted o-Carborane-1,2-dithiolate Ligand
Xiao Tang, Zhaojin Wang, Yizhi Li, Hong Yan*
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering,
Nanjing University, Nanjing, Jiangsu 210093, China. Fax: (+86)-25-83314502; E-mail:
hyan1965@nju.edu.cn.
Dedicated to Professor Vladimir I. Bregadze on the occasion of his 75th birthday.
Abstract. The 16-electron (16e) half-sandwich complex CpCo(S2C2B10H8)(CH=CHCO2Me)2 (1; Cp
= cyclopentadienyl) was considered as inert owing to hindered di-substitution at B sites. However in
methanol complex 1 reacts with ethynylferrocene (FcC≡CH) and dimethyl acetylenedicarboxylate
(DMAD, MeO2CC≡CCO2Me) to lead to two-fold alkyne insertion at Co−S bond to give rise to
unusual stable 18e adduct CpCo(S2C2B10H8)(CH=CHCO2Me)2(HC=CFc)(MeO2CC=CCO2Me) (2)
containing mixed alkynes. Also in methanol complex 1 undergoes intramolecular hydrogen transfer
of one CH=CHCO2Me unit to adjacent carbon to form a CH2CCO2Me unit, thus producing the 18e
complex CpCo(S2C2B10H8)[CH2CCO2Me][CH=CHCO2Me] (3). Further investigation indicates that
complex 1 can catalyze [2+2+2] cycloaddition of alkynes. The catalytic efficiency is determined by
temperature and nature of alkynes. In THF in the presence of [N(n-Bu)4]Br complex 1 is transformed
to ionic complex [N(n-Bu)4]+[Co(S2C2B10H8)2(CH=CHCO2Me)4]− (4), in which metal-dithiolene is
planar. Analogous [N(n-Bu)4]+[Co(S2C2B10H9)2(CH=CHCO2Me)2]− (5) was also synthesized from
mono-substituted precursor CpCo(S2C2B10H9)(CH=CHCO2Me) (1’). The electrochemical properties
of both 4 and 5 show significant negative shift of redox peaks versus the analogous
−
bis(1,2-benzenedithiolato)cobaltate (III) (Co(bdt)2 ). Reactivity of both neutral 16e CpCo complexes
and ionic metal-dithiolene derivatives declines with the increase of substituents on carborane cage.
All the new compounds have been characterized by NMR, IR, mass spectrometry, elemental analysis,
and 2, 3, and 4 have been structurally characterized by X-ray diffraction.

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Scheme 1. Reported examples from the reactions of 16e CpCo half-sandwich complex (A) containing
an o-carborane-1,2-dithiolate ligand with alkynes (B [9c], C [9a], D [10a], E [10a], F [10a], G [10a],
H [8a])
Introduction
Carboranes have been extensively studied in materials [1], microelectronics [2], optics [2,3] and
medicine [2−4] owing to their thermal stability, structural symmetry, unique electronic properties and
low bio-toxicity. Amongst the known polyhedral carboranes, 1,2-dicarba-closo-dodecaborane
(o-carborane) has been particularly studied. Mononuclear 16e half-sandwich complexes
Cp#M(E2C2B10H10) (Cp# = Cp, Cp*; M = Co, Rh, Ir; E = S, Se) and (p-cymene)M(S2C2B10H10) (M =
Ru, Os) possessing an o-carborane-1,2-dichalcogenolate ligand have been used to construct
metal-metal bonds in metallic clusters [5]; to react with Lewis bases for 18e congeners [6]; and
especially to react with alkynes to prepare B−H functionalized compounds in multi-step sequences
[7]. These sterically congested, coordinatively unsaturated compounds can be stored conveniently
and used for completion of various chemical transformations.
We have previously investigated the reactivity of above 16e complexes in terms of metal center
[7a−c, 8], chalcogen element [7a−d, 9], ancillary ligand [8a−c], substrate [8b−d, 10], temperature [9a,
10a], solvent [8a, 9b] as well as stoichiometry [10a]. However, the influence of substitution at
carborane cage remains largely unexplored [8e, 10a]. Though stepwise and selective carborane

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substitution in B3/B6 positions of CpCo(S2C2B10H10) has been reported [10a], the influence of
substituents at carborane on the properties and reactivity of these CpCo 16e half-sandwich complexes
is not considered.
B3/B6 disubstituted 16e compound CpCo(S2C2B10H8)(CH=CHCO2Me)2 (1) has been reported
[9a] and appeared to be a final product in aprotic solvents. In our recent study of reactivity of starting
complex A (Scheme 1) adjusting reaction conditions (for instance, temperature, solvents and reagents)
has delivered surprising results [8a,10b]. Thus, in this paper we investigate the influence of boron
substituents on the reactivity of the 16e CpCo half-sandwich complex (1) containing B-substituted
o-carborane-dithiolate ligand.
Scheme 2. Products from the reactions of 1 in this study
Results and discussion
Reaction of 1 with alkynes in CH3OH. Complex 1 shows no reactivity towards alkynes even under
heating in aprotic solvents (for instance, dichloromethane, chloroform and toluene). However, our
previous report on the starting 16e compound A (Scheme 1) proved that choice of solvents may lead
to different pathways of reaction [8a]. Considering that 1 may still possess reactivity because of its
unsaturated 16e metal center, two types of alkynes (ethynylferrocene (FcC≡CH) and ferrocenyl

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ethynyl ketone (Fc(CO)C≡CH)) were selected to detect the reactivity of 1 in methanol. Despite its
poor reactivity towards the two alkynes, 1 can react with FcC≡CH if dimethyl acetylenedicarboxylate
(DMAD, MeO2CC≡CCO2Me) is added to give complex 2 as a purple solid in a yield of 30%
(Scheme 2). Complex 2 is characterized by using spectroscopic data and X-ray crystal structure
determination. The solid-state structure of 2 (Figure 1) indicates that the two olefinic substituents on
boron are in a cisoid arrangement, like two chelas of a crab. Two types of alkynes are inserted into
the Co−S1 bond to form a six-membered ring which is on the same side with the boron substituents.
The two alkynes adopt a “head to tail” mode in which C19 connects with S1 and Fc group to evade
the hindrance from inserted DMAD and boron-substituents. The bulky Fc group stands above one
B-substituent, and the whole molecule takes a perfect steric arrangement. Similar insertions of
two-fold alkynes into a M−S bond are common [8b−d, 9, 10a], for example, in C [9a] and F [10a] in
Scheme 1, but complex 2 is precious as it is the first isolated 18e example bearing both a
six-membered Co−C=C−C=C−S ring and two CH=CHC(O)R groups at B3 and B6 sites for a CpCo
half-sandwich complex containing an o-carborane-1,2-dithiolate ligand. In particular, unlike other
similar compounds mentioned above, there are two different alkynes stepwise and stereoselectively
inserted into a Co−S bond of complex 1.
Figure 1. Molecular structure of 2. Ellipsoids show 30% probability levels, and hydrogen atoms have been omitted
for clarity. Selected bond lengths (Å) and angles (°): Co(1)−S(1) 2.195(7); Co(1)−S(2) 2.265(8); C(1)−C(2)
1.633(3); C(1)−S(1) 1.825(2); C(2)−S(2) 1.772(2); B(3)−C(8) 1.559(4); B(6)−C(12) 1.556(4); Co(1)−C(16)
1.943(2); C(16)−C(17) 1.351(3); C(17)−C(18) 1.456(3); C(18)−C(19) 1.338(3); C(19)−S(1) 1.773(2). S(1)Co(1)S(2)
92.83(2); C(1)S(1)Co(1) 108.30(7); C(19)C(18)C(17) 131.56(2); C(18)C(17)C(16) 125.79(2); C(17)C(16)Co(1)

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126.90(16)䟜 S(1)C(1)C(2)S(2)/S(1)Co(1)S(2) 1.00; C(16)C(17)C(18)C(19)/C(16)Co(1)S(1)C(19) 10.20.
1
The NMR data supports solid-state structure of 2. The HNMR spectrum shows characteristic
doublets at 5.94, 6.10, 6.71 and 6.79 ppm for the two CH=CHCO2Me units with coupling constants J
= 15 Hz, corresponding to the Z configuration. Owing to the impact of the Fc group and the inserted
DMAD, the hydrogen atoms on the two CH=CHCO2Me units exhibit notably different chemical
shifts. A singlet at 7.76 corresponds to the H atom in the six-membered Co−C=C−CH=C−S ring. The
four methoxyl groups each present a unique singlet from 3.55 to 3.90 ppm. In the 13C NMR spectrum
the two broad resonances at 135.1 and 139.7 are attributed to the two vinyl carbons bonded to boron
atoms. The four olefinic carbon atoms of the Co−C=C−CH=C−S unit are in turn assigned at 161.3,
132.7, 137.8 and 114.7 ppm, established unambiguously by 1H/13C Heteronuclear Multiple Quantum
Coherence (HMQC) and Heteronuclear Multiple Bond Coherence (HMBC) experiments.
It is known that 1 exists as two conformers in its solid-state structure [8d], i.e. both cisoid and
transoid arrangements based on the orientation of the two boron-substituents. The solid state
structure of complex 2 adopts only a cisoid arrangement for the two vinyl groups. Previous reports
showed that compounds like 2 usually can react with one alkyne to give cyclotrimerized products,
thus served as precursors for benzene derivatives [7g, 9a, 9c] . The synthesis of 2 revealed the
potential of complex 1 to be a catalyst for [2+2+2] cyclotrimerization of alkynes.
Interestingly, in all the reactions of complex 1 in methanol, including individual treatment of 1,
complex 3 in gray-blue color was generated. Isolation and characterization with NMR and X-ray
diffraction suggests that complex 3 arises from rearrangement of 1. Its solid-state structure (Figure 2)
displays a new B−CH2 unit (C3) and a chiral carbon (C4). One of the carbon-carbon double bonds in
1 has extended to the range of single bond in 3. Characteristic diastereotopic signals for the B−CH2
hydrogen atoms (J = 16 Hz) are observed at 1.37 and 2.20 ppm. And the two vinyl proton signals at
6.48 and 6.64 ppm split into doublets (coupling constant J = 15 Hz) in accordance with a Z
configuration. The 13C NMR spectrum displays two broad resonances at 26.6 and 138.1 ppm,
11
corresponding to the methylene and vinyl carbon atoms bonded to B6 and B3, respectively. The B
NMR spectrum shows the pattern of overlapping signals as expected for unsymmetrically substituted
o-carborane derivatives. Characteristically, a low-field shift for the substituted boron atom connected

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with alkyl group was observed at 5.0 ppm relative to negative values for the other boron signals. A
similar chemical shift appeared in B [9c] and G [10a] (Scheme 1) for B-substituted carboranes. The
MS data of 3 shows accordance with 1 (498 for both). All data are consistent with the solid state
structure.
Figure 2. Molecular structure of 3. Ellipsoids show 30% probability levels, hydrogen atoms have been omitted for
clarity. Selected bond lengths (Å) and angles (°): Co(1)−S(1) 2.191(2); Co(1)−S(2) 2.174(19); Co(1)−C(4) 2.004(6);
C(1)−S(1) 1.638(6); C(2)−S(2) 1.768(5); S(2)−C(4) 1.745(6); C(1)−C(2) 1.683(8); C(7)−C(8) 1.366(9); B(3)−C(7)
1.626(8); B(6)−C(3) 1.411(9). S(1)Co(1)S(2) 96.30(6); S(1)Co(1)C(4) 96.16(14); S(2)Co(1)C(4) 49.18(16);
S(2)C(2)C(1) 116.14(1); S(1)C(1)C(2) 118.68(4); C(4)C(3)B(6) 111.15(5); C(8)C(7)B(3) 137.29(6);
S(1)Co(1)S(2)/S(1)C(1)C(2)S(2) 8.6; C(4)Co(1)S(2)/S(1)Co(1)S(2) 92.7.
Similar structures were reported by our group, for example, complex F [10a] (Scheme 1) and
CpCo(Se2C2B10H8)[CH2CCO2Me][HC=CHCO2Me] [9a]. The former example represents two types
of alkyne stereoselective addition by two different types of alkynes [10a], but the latter exhibits two
types of alkyne addition modes determined by the size of Se atom [7d, 8e, 9a]. Unlike these similar
structures which come from direct addition of alkynes to Co−S bonds and following B−H activation
[8d,9a,10a], the generation of 3 has no involvement of additional alkynes. As the conversion is not
observed in aprotic solvents, methanol must have played an important role. However, a methanol
mediated proton exchange mechanism is not appreciable (SI-Scheme 1), given that deuterated
methanol brings no change to the NMR spectra. Thus an intramolecular hydrogen shift mechanism
was proposed as shown in Scheme 3. First, one CH=CHCO2Me group rotates to a position closer to
the Co−S1 bond in methanol, then the electrophilic S1 atom attacks the electron-rich α-carbon,
weakens the Co−S1 bond so that the metal centre could approach CH=CHCO2Me group, followed by
the interaction between metal center and carbon-carbon double bond in the CH=CHCO2Me group as

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well as C(α)−H activation. Afterwards comes hydrogen transfer to β-carbon and formation of
C(α)−Co, C(α)−S1 bonds. In literature similar cobalt center was found to exhibit β-agostic interaction
[11] (a process consisting of β-H elimination/olefin rotation/reinsertion) and α, β unsaturated
carboxylic esters can undergo Co-catalyzed α-carbon electrophilic addition [12].
S
Co
S
S
Co
S
CO2Me
CO2Me
CH3OH
MeO2C
MeO2C
MeO2C
I
1
Co
S
Co
S
3
S
H
MeO2C
S
CO2Me
CO2Me
H2C
MeO2C
B
C
II
Scheme 3. A probable mechanism for transformation of 1 to 3 in methanol
Catalytic reactions of 1 in toluene. Numerous transition metal complexes have been developed as
effective catalysts or precursors for [2+2+2] cyclotrimerization of alkynes [13], among them Co
complexes are favored owing to their low cost and relatively low environmental impact [14]. CpCoL
complexes have been used most widely, where the nature of ligand L influences the behavior of the
catalyst: too effective stabilization retards initiation of the catalyst, while with too weak stabilizing
ligands the complex tends to decomposition [15]. Thus efforts have been made to develop an
effective catalyst. We have reported a catalytic pathway through synergic M and S atoms by
CpCo(S2C2B10H10) [8d, 9a, 9c] (A, Scheme 1), the precursor of 1, but a competitive B−H activation is
present. Nonetheless, the potential reaction sites B3 and B6 have all been occupied in complex 1.
Thus complex 1 is expected to have better catalytic efficiency.

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Scheme 4. Catalysis of 1 towards cyclotrimerization of alkynes
Table 1. Catalysis of 1 towards cyclotrimerization of alkynes
Entry
Alkynes
Temperature
Time
(hours)
4
CAT amount
%mol
2%
Yield
(isolated)
95%
a:b
ratio
——
1:3
oC
70
1
2
R1=R2=CO2Me
R1=H, R2=CO2Me
R1=H, R2=CO2Me
R1=H, R2=Ph
110
70
12
2%
59%
3
12
2%
14%
1:3
4
110
110
70
12
2%
71%
1:2
5
R1=H, R2=Ph
12
4%
73%
1:2
6
R1=H, R2=Ph
12
4%
——
50%
——
——
——
——
——
7
R1=H, R2=Ph(CO)
R1=H, R2= C10H7(CO)
R1=H, R2= Fc(CO)
R1=H, R2= Fc
110
110
110
110
12
4%
8
12
4%
38%
9
12
4%
——
——
10
12
4%
The catalytic performance of 1 for the cyclotrimerization of different alkynes in toluene at different
temperatures was studied (Scheme 4) and the results are shown in Table 1. Five of the alkynes tested
gave the desired products as two isomers a and b in moderate to excellent yields (38−95%). The 1,2,4
cyclotrimer is favored for terminal alkynes (for example, a:b ratio of 1:3 for HC≡CCO2Me and 1:2
for PhC≡CH). Cyclotrimerization of alkynes bearing planar hindrance group (Ph(CO)− or
C10H7(CO)−) are formed in lower yields (entries 7, 8) whereas alkynes bearing bulky steric groups of
ethynylferrocene (FcC≡CH) and ferrocenyl ethynyl ketone (Fc(CO)C≡CH)) would not give objective
products (entries 9, 10). This demonstrates that steric hindrance of the substituents on the carborane
cage of the catalyst 1 plays vital role in catalytic efficiency. Increasing temperature is favored (see
entries 2 and 3; 5 and 6). Note that significant degradation of 1 was observed in the catalytic process
of MeO2CC≡CCO2Me and C10H7(CO)C≡CH, whereas in the alkynes bearing no

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electron-withdrawing group, complex 1 nearly remained.
Scheme 5. Reactions of 16e CpCo half-sandwich complexes containing an o-carborane-1,2-dithiolate
ligand with [N(n-Bu)4]Br. From A to I see ref. 16.
Reactions of B-substituted 16e CpCo compounds to form metalladithiolene complexes. The 16e
complex CpCoS2C2B10H10 (A) has shown to react with [N(n-Bu)4]Br in THF to produce
[N(n-Bu)4]+[Co(S2C2B10H10)2]− (I) [16], a type of metalladithiolene complex which can readily react
with alkynes to yield cobalt-free carboranyl vinyl sulfides [10b,16]. Hoping to further study the
reactivity of 1 and get similar B-substituted cobalt-free carboranyl vinyl sulfides, we tried this
reaction. As expected, complex was isolated (Scheme 5) in a yield of 37%. The crystals suitable for
X-ray analysis were obtained and the solid-state structure was solved, as shown in Figure 3. The
coordination centre of 4 (tetra-substituted) is in a planar geometry, evident by the dihedral angle of
S(1)Co(1)S(2A)/S(2)Co(1)S(1A) (0). Also the two five-membered rings Co−S−C−C−S are planar.
The four CH=CHCO2Me units appear as “fences” to protect the planar coordination centre from two
sides. Similarly, the ionic complex [N(n-Bu)4]+[Co(S2C2B10H9)2(CH=CHCO2Me)2]− (5, di-substituted)
was synthesized starting from B-monosubstituted 16e complex CpCo(S2C2B10H9)(CH=CHCO2Me)
(1′) (Scheme 5). The formation of B-substituted ionic products requires longer time. All these ionic
species are paramagnetic, prohibiting NMR characterization as reported for complex I [16].

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Figure 3. Molecular structure for the anion of 4. Ellipsoids show 30% probability levels, and some of the hydrogen
atoms have been omitted for clarity. Selected bond lengths (Å) and angles (°): C(1)−C(2A) = 1.612(4); Co(1)−S(1)
= 2.182(10); Co(1)−S(2) = 2.165(10); B(3)−C(7) = 1.546(5); C(7)−C(8) = 1.333(5); B(6)−C(3) = 1.554(5);
C(3)−C(4)
=
1.313(5); S(1)Co(1)S(2A)
=
94.71(3); S(1)Co(1)S(2A)/S(2)Co(1)S(1A)
=
0.00;
S1ACo1S2/S2C2C1AS1A = 179.7
The complexes 4 (tetra-substituted), 5 (di-substituted) and I (non-substituted) show significantly
difference in reactivity. For example, complex 4 shows no reactivity towards activated alkynes even
heated up to 110 oC. Complex 5 does not react with alkynes at room temperature, when heated to 50
oC, a complicated reaction mixture was obtained. In comparison, complex I could readily react with
alkynes under ambient environment to give rise to metal-free carboranyl vinyl sulfides [10b,16]. In
addition, complex I reacts with N-donor ligands quickly (i.e. ammonia, hydrazine and acetonitrile)
with immediate color change to form 6-coordinate adducts. After removal of solvents, the color of
complex I is recovered. However, 4 is unable to coordinate with these ligands. Obviously, the
substitution groups of 4 play a critical role in its inert reactivity as four CH=CHCO2Me units prevent
the Co centre from being attacked. Surprisingly, neither I nor 4 react with P or S-donor ligands (i.e.
H2S and PMe3) or CO.
On the other hand, the known metalladithiolene complex, tetrabutylammonium
−
bis(1,2-benzenedithiolato) cobaltate(III) (Co(bdt)2 ) which possesses similar coordination
environment to 4, 5 and I has recently been found to serve as an active electrocatalyst for proton
reduction in the presence of weak acids [17]. Thus we also studied the electrochemical properties of
these carborane-functionalized metalladithiolene complexes for the potential as catalysts for proton

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reduction. The CV data (see SI Figure 2) show that in the absence of acid, a quasi reversible CoIII/II
redox peak is observed in each complex, with Ep vs Fc/Fc+ of −0.62 V for 4−/42− (tetra-substituted),
−0.65 V for 5−/52− (di-substituted) and −0.64 V for I−/I2− (non-substituted). The addition of
substituents on boron has little influence on the redox potentials. Note that these values are
−
significantly positive than that of Co(bdt)2 (−1.01V) [17], which indicates that the strong
electron-withdrawing effect of the carborane cage shifts the reduction peaks of Co(III) to the positive
direction. The catalysis of proton reduction is not observed in all these compounds. DFT calculations
at UB3LYP hybrid functional level is employed to give more insight into the electronic structure of
these complexes (see SI, DFT Calculations). The results show that the charge density on sulfur atoms
−
−
of Co(bdt)2 and Co(S2C2B10H10)2 are quite different: the charge density on the sulfur atoms of
−
−
Co(bdt)2 is −0.03 whereas 0.1 on Co(S2C2B10H9)2 . Recent studies raise the possibility that
protonation of the sulfur atoms on the dithiolene ligands after the initial CoIII/II reduction may play a
critical role in the reduction of protons to dihydrogen and that electron-withdrawing groups on the
dithiolene substituents is not favorable for their reduction activity18. It is likely that
electron-withdrawing carborane cages of 4, 5 and I result in the difficulty of protonation on sulfur
atoms, and thus inhibit the reduction of protons [18].
Thus it is clear that the reactivity of complexes containing o-carborane-1,2-dithiolate ligand
declines with the increase of substituents on carborane cage. In the case of neutral 16e CpCo species,
CpCo(S2C2B10H10) (A) could readily react with alkynes at ambient temperature and give a variety of
products [8a,8d,9,10]. The B3/B6 disubstituted CpCo 16e complex (1) reacts with certain alkynes
only at high temperatures (70~110 ) [9a] for catalytic trimerization of alkynes or in protic solvents,
such as MeOH, yields are also significantly lower. The metalladithiolene species like complexes from
I (non-substituted), 5 (di-substituted) to 4 (tetra-substituted) also show decreasing reactivity with the
increasing numbers of substituents at boron sites.
Table 2. Calculated information on three 16e CpCo complexes containing an
o-carborane-1,2-dithiolate ligand. CpCo(S2Ph) is included for comparison.
Compound
HOMO(eV) LUMO(
eV)
HOMO−LUMO
GAP(eV)
Charge on S
Co−S bond
length

ACCEPTED MANUSCRIPT
CpCo(S2C2B10H10)
−6.278
−6.296
−3.990
−4.008
2.288
2.288
0.08
2.16[2.13]a, 6a
CpCo(S2C2B10H9)
(CH=CHCO2Me)
CpCo(S2C2B10H8)
(CH=CHCO2Me)2
(cisoids)
S1 = 0.07
S2 = 0.10
S1 = 0.07
S2 = 0.12
2.15
2.17
−6.311
−4.038
2.273
2.590
2.15[2.13]a, 9a
2.17[2.14]a, 9a
CpCo(S2Ph)
−5.605
−3.015
−0.09
2.24
a data in the brackets are experimental values
DFT study
DFT calculations were used to gain more insight into the electronic structures and orbital
properties of the three 16e complexes. Calculation on CpCo(bdt) (bdt: bis(1,2-benzenedithiolato))
was also conducted for comparison. Computational results (Table 2) suggest that the HOMO/LUMO
energy levels of three CpCo 16e complexes decline very slightly with increasing number of boron
substituents while the HOMO/LUMO energy gaps and configurations are nearly the same for the
three complexes, leading to the conclusion that their difference on reactivity towards alkynes is more
likely attributed to steric and configurational factors. Former report suggested that the first step
reaction of CpCo 16e complexes towards alkynes involves the insertion of alkynes into a Co−S bond
[9a]. In complex 1, steric hindrance from substituents affects both Co−S bonds, making the attack of
alkynes quite difficult. Additionally, because the B3/B6 sites are occupied, M--H--B interaction can
not occur, nor does boron loss in methanol. All these may have contributed to the low reactivity of
complex 1. As to metalladithiolene complexes 4 (tetra-substituted), 5 (di-substituted) and I
(non-substituted), reactions begin with alkyne or ligand approaching metal center [10b], substituents
on boron atoms will encumber this process, just as the crystal structure of 4 reflects.
Conclusion
The reactivity of 16e compound CpCo(S2C2B10H8)(CH=CHCO2Me)2 (1) was investigated. In
methanol selective alkyne insertion into Co−S bond of 1 occurs to form 2 in which two different
alkynes are stepwise and stereoselectively inserted into one Co−S bond. A Co(III)-mediated H-shift is
responsible for the rearrangement of 1 to 3 in methanol which acts via a Co−H agostic bond followed
by reduction of a C=C double bond and generation of B−alkyl bond. The catalytic activity of 1
towards the cyclotrimeriztion of a range of alkynes was studied and 1 was found to be a moderate

ACCEPTED MANUSCRIPT
catalyst. Square planar Co(III)-dithiolene complexes 4 (tetra-substituted) and 5 (di-substituted)
containing B-substitution at carborane were synthesized and their electrochemical properties were
−
studied and compared with Co(bdt)2 . The number of substituents on B3/B6 sites plays a critical role
in the reactivity of these 16e compounds and metalladithiolate complexes. Also the
electron-withdrawing effect of carborane cage significantly changes the electrochemical properties of
metalladithiolate complexes. Computational studies were combined for better understanding of this
system. This work throws more light on the understanding of the reaction chemistry of the two types
of complexes: 16e CpCo half-sandwich complexes and square planar Co(III) species containing
o-carborane-1,2-dithiolate ligand.
Experimental section
General Information. n-Butyllithium (2.0 M in hexanes, Aldrich) was used as supplied. The
complexes CpCo(CO)I2 [19], CpCo(S2C2B10H10) (A) [6a], CpCo(S2C2B10H8)(CH=CHCO2Me)2 [9a]
(1) and [N(n-Bu)4]+[Co(S2C2B10H10)2]− (I) [16] were prepared by literature procedures. All reactions
were carried out under argon using standard Schlenk techniques except otherwise noted. All solvents
were dried and deoxygenated prior to use. Diethyl ether, tetrahydrofuran and petroleum ether were
refluxed and distilled over sodium/benzophenone ketyl under nitrogen. Methanol was distilled over
Mg/I2. CH2Cl2 was refluxed and distilled over CaH2 under nitrogen. The NMR measurements were
performed on a Bruker DRX 500 spectrometer. Chemical shifts were given with respect to
CHCl3/CDCl3 (δ(1H) 7.24 ppm; δ(13C) 77.0 ppm) and external Et2O·BF3 (δ(11B) 0 ppm). The IR
spectra were recorded on a Bruker Vector 22 spectrophotometer with KBr pellets in the region of
4000−400 cm−1. Cyclic voltammograms (CV) were recorded on an Im6eX electrochemical analytical
instrument with platinum disk as the working electrode, platinum wire as the counter electrode, and
an Ag/AgCl electrode as the reference electrode. Ferrocene was used as external standard for all
electrochemical experiments. The electrolyte for electrochemical measurements in 1:1 CH3CN:H2O
was KNO3 (0.1 M). The concentration of 4, 5 and I was 0.5 mM. All the potentials were run at a scan
rate of 100 mV/s.
Preparation of CpCo(S2C2B10H8)(CH=CHCO2Me)2(HC=CFc)(MeO2CC=CCO2Me) (2). A
mixture of 1 (100 mg, 0.2 mmol), ethynylferrocene (84 mg, 0.4 mmol) and dimethyl

ACCEPTED MANUSCRIPT
acetylenedicarboxylate (0.4 mL, 0.4 mmol) in MeOH (20 mL) was stirred for 48 h at ambient
temperature to give a dark brown solution. After removal of the solvent, the residue was
chromatographed on TLC and elution with petroleum ether/CH2Cl2 gave 2 (51 mg, 30%), 3 (20 mg,
o
1
20%) and unreacted 1 (30.0 mg, 30%). 2: purple solid; m.p. 278−282 C. H NMR (CDCl3): δ 3.55,
3.83, 3.85. 3.90 (s, 3H, OMe for each), 4.09 (s, 5H, Fc−Cp), 4.39 (m, 1H, Fc−CH), 4.41 (m, 1H,
Fc−CH), 4.64 (m, 1H, Fc−CH), 4.85 (m, 1H, Fc−CH), 5.33 (s, 5H, Co−Cp), 5.94, 6.10, 6.71, 6.79 (d,
1H, J = 15 Hz for two CH=CHCO2Me units), 7.76 (s, 1H, S−C=CH). 13C NMR (CDCl3): δ 50.7, 51.7,
52.1, 52.6, (OCH3), 68.5, 69.2, 69.7, 70.2, 70.5, 83.5 (Fc), 91.5 (Co-Cp), 93.3, 96.2 (carborane),
114.7 (S−C=), 132.3, 135.0, (B−CH=CH), 132.7 (Co−C=C), 135.1, 139.7 (br, B−CH=), 137.8
(S−C=CH), 161.3 (Co−C=), 162.6, 166.5, 167.4 176.3 (C=O). 11B{1H} NMR (CDCl3): δ 0 (2B,
B−C), −3.3 (3B), −7.0 (3B), −9.6 (2B). Anal. Calcd for C33H39B10CoFeO8S2: C, 46.60; H, 4.58.
Found: C, 46.21; H, 4.70. ESI-MS: m/z 849 (M+, 80%). IR (KBr): ν (cm−1) 1707, 1716, 1730 (C=O),
2602 (B−H).
Transformation of CpCo(S2C2B10H8)(CH=CHCO2Me)2 (1) to CpCo(S2C2B10H8)
[CH2CCO2Me][CH=CHCO2Me] (3). A solution of 1 (100 mg, 0.2 mmol) in MeOH (20 mL) was
stirred for 48 h at ambient temperature to lead to a brown solution. After removal of the solvent, the
residue was chromatographed on TLC and elution with petroleum ether/CH2Cl2 to give 3 (35 mg,
o
1
35%) and 1 (50 mg 50%). 3: grey blue solid; m.p. 190−193 C. H NMR (CDCl3): δ 1.37 (br, d, J =
17 Hz, 1H, B−CH2), 2.20 (br, d, J = 17 Hz, 1H, B−CH2), 3.80 (s, 3H, OMe), 3.81 (s, 3H, OMe), 4.82
(s, 5H, Co−Cp), 6.48 (d, 1H, J = 15 Hz, =CH), 6.64 (br, d, 1H, J = 15 Hz, B−CH=). 13C NMR
(CDCl3): δ 26.6 (br, B−CH2), 51.5, 52.7 (OCH3), 70.9 (S−C−Co), 85.6 (Cp), 95.4, 98.6 (carborane),
11
133.9 (=CH), 138.1 (br, B−CH=), 166.7, 177.8 (C=O). B{1H} NMR (CDCl3): δ 5.0 (1B, B−CH2),
−2.8 (1B), −3.8 (1B), −6.4 (6B), −11.3 (1B). Anal. Calcd for C15H23B10CoO4S2: C, 36.11; H, 4.61;
Found: C, 35.77; H, 4.47. ESI-MS: m/z 498 (M+, 70%). IR (KBr): ν (cm−1) 1621 (C=C), 1702, 1719
(C=O), 2585 (B−H).
Preparation of [N(n-Bu)4]+[Co(S2C2B10H8)2(CH=CHCO2Me)4]− (4). To a solution of 1 (200 mg,
0.4 mmol) in dry THF (30 mL) at ambient temperature [N(n-Bu)4]Br (130 mg, 0.4 mmol) was added
for 6 h, the color changed from orange to yellowish green. Then the solvent was removed under
reduced pressure, and the resulting residue was chromatographed on silica gel and elution with
CH2Cl2/ethyl acetate to give compound 4 (78.0 mg, 37%). Compound 4: yellowish green solid. m.p.

ACCEPTED MANUSCRIPT
218−220
oC.
ESI-MS
(positive
and
negative
ion
modes,
m/z):
808
for
[Co(S2C2B10H8)2(CH=CHCO2Me)4]− and 242 for [N(n-Bu)4]+. Anal. Calcd for C36H72B20NCoO8S4: C,
41.13; H, 6.85. Found: C, 40.79; H, 6.69. IR (KBr): ν (cm−1): 1619 (C=C), 1732 (C=O), 2589 (B−H).
Preparation of CpCo(S2C2B10H9)(CH=CHCO2Me) (1′). To a solution of A (200 mg, 0.6 mmol)
in dry CH2Cl2 (30 mL) at ambient temperature was added HC≡CCO2Me (0.17 ml, 2.0 mmol) and
stirred for 3 h, the color changed gradually from rose to brownish red. Then the solvent was removed
under reduced pressure, and the resulting residue was chromatographed on TLC and elution with
CH2Cl2/hexanes gave compound 1’ (83 mg, 33%). Orange solid. m.p. 191−193 oC. ESI-MS: m/z 414
(M+, 67%). Anal. Calcd for C11H19B10CoO2S2: C, 31.85; H, 4.58. Found: C, 31.53; H, 4.69. IR (KBr):
ν (cm−1): 1606 (C=C), 1712 (C=O), 2583 (B−H).
Preparation of [N(n-Bu)4]+[Co(S2C2B10H8)2(CH=CHCO2Me)2]− (5). To a solution of
CpCo(S2C2B10H9)(CH=CHCO2Me) (1′) (166 mg, 0.4mmol) in dry THF (30 mL) at ambient
temperature was added [N(n-Bu)4]Br (130mg, 0.4mmol) for 6 h, the color changed gradually from
orange to yellowish green. Then the solvent was evaporated under reduced pressure, and the resulting
residue was chromatographed on silica gel and elution with CH2Cl2/ethyl acetate gave compound 5
(61.7 mg, 35%). Green solid. m.p. 216−218 oC. ESI-MS (positive and negative ion modes, m/z): 640
for [Co(S2C2B10H9)2(CH=CHCO2Me)2]− and 242 for [N(n-Bu)4]+. Anal. Calcd for
C28H66B20NCoO4S4: C, 37.99; H, 7.46. Found: C, 37.63; H, 7.31. IR (KBr): ν (cm−1): 1618 (C=C),
1730 (C=O), 2587 (B−H).
General procedure for the alkyne cyclotrimerization. The corresponding alkyne, the catalyst
and toluene (10 mL) were introduced in a schlenk tube and the reaction mixture was stirred at 70 oC
or 110 oC for the indicated time (see Table 1 and Scheme 4). The resulting arenes were isolated by
TLC using petroleum ether/CH2Cl2 as eluents and confirmed by NMR and GC-mass spectroscopy.
More detailed information can be seen in SI.
Computational Methods. All calculations were performed with Gaussian 09 package.
Calculations were performed at the density functional theory (DFT) level of (U)B3LYP. Geometry
optimization was conducted with a combined basis set in which Co was described by LANL2DZ
basis set, and 6-31G(d, p) was used for the other atoms.
X-ray Crystallography. Crystals suitable for X-ray analysis were obtained by slow evaporation of
a solution in petroleum ether/dicloromethane or petroleum ether/ether. Diffraction data were

ACCEPTED MANUSCRIPT
collected on a Bruker SMART Apex II CCD diffractometer using graphite-monochromated Mo-Kα
(λ = 0.71073Å) radiation at 273 K. During the intensity data collection, no significant decay was
observed. 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. Crystal data, data collection parameters, and the results of the analyses of 2 (CCDC
923666), 3 (CCDC 923667), 4 (CCDC 923668) are listed in Table 3.
Table 3 Crystallographic data and structure refinement information for 2–4.
Compounds
chemical formula
formula weight
crystal size (mm)
temperature (K)
crystal system
space group
a(Å)
2
C33H39B10CoFeO8S2
850.64
3
C15H23B10CoO4S2
498.48
4
C36H72B20CoNO8S4
1050.32
0.13×0.12×0.01
296(2)
0.24×0.20×0.15
296(2)
0.28×0.24×0.22
291(2)
monoclinic
P2(1)/c
monoclinic
C2
monoclinic
C2/c
11.3296(18)
14.537(2)
23.140(4)
90.00
21.705(10)
7.786(4)
27.448(13)
90.00
17.535(5)
17.336(5)
19.368(6)
90.00
b(Å)
c(Å)
α(°)
β(°)
101.291(2)
90.00
92.884(8)
90.00
103.266(4)
90.00
γ(°)
V(Å3)
3737.3(11)
4
4633(4)
8
5730(3)
4
Z
ρ(calc) (g/cm3)
F (000)
1.512
1.429
1.217
1744
2032
2200
absorp.coeff. (mm−1)
θ range (deg)
reflns collected
0.995
0.942
0.489
1.66–26.00
20207
0.74–26.00
13543
1.67–26.00
15466
(Rint = 0.0619)
7334
(Rint = 0.0316)
8550
(Rint = 0.1284)
5617
indep. reflns

ACCEPTED MANUSCRIPT
5333
7277
2748
Refns obs. [I
䟟2σ(I)]
data/restr/paras
GOF
7334/0/532
0.917
8550/1/563
1.078
5617/2/321
0.985
0.0340/0.0717
0.04970.0751
0.377/–0.300
0.0595/0.1442
0.0702/0.1475
0.380/–0.639
0.0626/0.1510
0.1144/0.1660
0.422/–0.591
R1/wR2 [I䟟2σ(I)]
R1/wR2 (all data)
larg peak and hole(e/Å3)
Acknowledgement
The financial support from the National Natural Science Foundation of China (20925104, 21271102 and 21021062),
the Major State Basic Research Development Program of China (2013CB922100 and 2010CB923303) and
NSFC-RFBR joint grant (21110143 and 12-03-91165) is acknowledged.
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ACCEPTED MANUSCRIPT
Table of Contents
Reactivity of the 16-Electron CpCo Half-Sandwich Complex Containing a
B(3,6)-Disubstituted o-Carborane-1,2-dithiolate Ligand
Xiao Tang, Zhaojin Wang, Yizhi Li, Hong Yan*
In methanol the 16-electron complex 1 reacts with alkynes to lead to product 2. Complex 1 can also
isomerize to 3 in methanol. In the presence of [N(n-Bu)4]Br in THF complex 1 can be transformed to
ionic square-planar complex 4 which shows notably different electrochemical properties in contrast
to analogous carborane-free complexes.
MeO2
C
Co
Co
S
S
MeO2
C
MeO2
CO2Me
C
S
S
CO2Me
MeO2
C
Fc
S
Co
S
2
3
Fc
MeO2C
CO2Me
+
CO2Me
CH3OH / R.T.
CH3OH / R.T.
MeO2C
MeO2
C
CO2Me
1
S
S
Co
N(n-Bu)4
S
S
B
C
MeO2
C
CO2Me
4
N(n-Bu)4Br
THF / R.T.

ACCEPTED MANUSCRIPT
In methanol the 16-electron complex 1 reacts with alkynes to lead to product 2. Complex
1 can also isomerize to 3 in methanol. In the presence of [N(n-Bu)4]Br in THF complex 1
can be transformed to ionic square-planar complex 4 which shows notably different
electrochemical properties in contrast to analogous carborane-free complexes.

ACCEPTED MANUSCRIPT
1. The 16 electron complex CpCo(S2C2B10H8)(CH=CHCO2Me)2 reacts with selected
alkynes to lead to 18 electron insertion product in methanol.
2. In methanol a Co(III)-mediated H-shift occurs which may occur via a Co−H
agostic bond.
3. The complex CpCo(S2C2B10H8)(CH=CHCO2Me)2 shows a moderate catalyst for
alkyne cyclotrimeriztion.
4. In the presence of [N(n-Bu)4]Br the 16 electron complex can be efficiently
transformed to [N(n-Bu)4]+[Co(S2C2B10H8)2(CH=CHCO2Me)4]−.
5. The reactivity of both the 16 electron complex and the square planar
metalladithiolate complex dramatically declines as the number of boron
substituents increases. The steric effect, rather than electronic effect of the
B-substituents plays predominant role in reducing reactivity.

ACCEPTED MANUSCRIPT
Supporting Information
Reactivity of the 16-Electron CpCo Half-Sandwich Complex
Containing a B(3,6)-Disubstituted o-Carborane-1,2-dithiolate
Ligand
Xiao Tang, Zhaojin Wang, Yizhi Li, Hong Yan*
State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical
Engineering, Nanjing University, Nanjing, Jiangsu 210093, China. Fax:
(+86)-25-83314502; E-mail: hyan1965@nju.edu.cn.
SI Scheme 1. The proposed methanol-mediated H-shift mechanism for
transformation of 1 to 3.
1
SI Figure 1. Comparison of H spectra for the reactions of 1 to 3 in
methanol (in red) and deuterated methanol (in black)

ACCEPTED MANUSCRIPT
DFT Calculations
Computational Details. All calculations were performed with Gaussian09 program in
the framework of density functional theory (DFT). Effective core potential
LANL2DZ was used for metal Co, and 6-31G(d, p) was used for the other atoms.
Geometry optimization was carried out using the former basis set and B3LYP
functional. All open-shell calculations were performed using unrestricted methods,
and spin contamination was found to be very small.
Cartesian coordinates of optimized compounds
CpCo(S2C2B10H10) (A)
B
B
H
B
H
B
B
H
B
H
B
H
B
H
B
H
B
H
C
C
C
H
C
H
C
H
C
H
C
1.67872000
2.54689000
2.37868500
2.55406600
2.39090600
1.69052200
2.54769400
2.38003200
3.43634200
4.01746400
3.98562500
4.97992600
3.44776400
4.03717500
2.55480500
2.39217500
3.98609900
4.98069900
1.22399400
1.22446300
-3.54673200
-3.49615000
-3.50171500
-3.41194500
-3.54474000
-3.49207900
-3.55701100
-3.51580900
-3.56287600
-0.00058400
1.43891600
2.44959700
1.43961900
2.45080000
0.00030600
-1.43943700
-2.45075300
-0.00022800
-0.00047600
0.89440700
1.54055500
0.00066400
0.00109500
-1.43896200
-2.44989900
-0.89361400
-1.53930700
0.81855100
-0.81899300
-1.13054700
-2.13170100
0.08313900
0.15474000
1.18353000
2.22980800
0.65223100
1.22374600
-0.78100100
1.45743500
0.89472800
1.48575800
-0.88997000
-1.48156900
-1.46065600
0.89390000
1.48398400
1.45221300
2.48571100
0.00794400
0.01206600
-1.44130200
-2.47009000
-0.89085100
-1.48304100
0.00738300
0.01108600
-0.00326800
-0.00374500
0.46326000
0.86766000
1.22113900
2.29639500
0.30981700
0.57601800
-1.00745400
-1.92435700
-0.91191000

ACCEPTED MANUSCRIPT
H
Co
S
-3.52735000
-1.84004000
-0.40052200
-0.39973100
0.91771700
0.89874600
-1.46930300
-0.00155900
1.60958600
-1.61039000
0.00040400
-0.00123400
-1.74486500
-0.01203100
-0.01057700
-0.01078000
-2.35060200
2.34125100
S
H
H
Co(S2C2B10H9)(CH=CH−CO2Me) (1’)
B
B
H
B
H
B
B
H
B
H
B
H
B
H
B
H
B
H
C
C
C
H
C
H
C
C
H
H
H
C
H
C
H
C
H
1.35257900
1.88309600
2.32966700
0.74912700
0.46273000
-0.55048200
1.28346900
1.32432800
2.60972200
3.70106200
2.27150500
3.14490400
0.76724100
0.54655900
0.15496100
-0.55036300
1.89968400
2.50782600
0.19949400
-0.13811600
1.31233400
0.40871100
2.19761300
1.96322200
3.51740000
5.40151100
6.09916500
5.73348500
5.33722000
-4.12629900
-4.41028900
-3.31491600
-2.87492700
-3.12858700
-2.52437400
0.54811500
1.20091400
0.44334800
2.45804600
2.50678400
2.64435300
1.91004300
1.64440900
1.77426700
1.46442300
2.92481300
3.42763200
3.80177000
4.91604900
3.17155900
3.72084500
3.36527200
4.18510500
1.10114200
1.50686400
-0.93915800
-1.19055700
-1.94809300
-2.90014800
-1.93094800
-3.26369200
-2.54077600
-4.28258200
-3.08574300
-1.11684700
-0.66377400
-2.27081100
-2.85596900
-2.49340200
-3.27346300
-0.43173300
1.13238700
1.91798000
1.69971500
2.84651200
0.51520900
-1.59013300
-2.74271300
-0.40018800
-0.73131100
0.91733700
1.54188900
0.53098400
0.87138000
-1.01721100
-1.79194900
-0.77578500
-1.37957800
0.80520400
-0.73083300
-0.92695700
-1.48265200
-0.84717400
-1.31727600
-0.17096400
0.30625300
-0.12472900
0.10580900
1.38307000
-0.96496500
-1.90433200
-0.80134200
-1.59707400
0.60591500
1.04783300

ACCEPTED MANUSCRIPT
C
H
C
H
Co
O
O
S
-3.81290000
-3.82205900
-4.40294800
-4.93771100
-2.35676900
4.03689400
4.10922200
-0.86385100
-1.54962300
-1.69176200
-1.46816200
-1.32167000
-0.59350400
0.32152300
-0.61746400
-1.00805400
-3.14738100
-0.16219700
0.67195900
2.74728800
1.30608700
2.37698300
0.33531300
0.54960700
0.05515000
0.42237800
-0.30479500
1.54032400
-1.48987800
0.79156800
S
H
1(cis)
B
B
H
B
H
B
B
H
B
H
B
H
B
H
B
H
B
H
C
C
C
H
C
H
C
C
H
H
H
C
H
1.53174200
0.89264900
1.44400700
-0.89389000
-1.44486200
-1.53268500
0.89386900
1.46888200
1.44494900
2.46480700
-0.00128100
-0.00160100
-1.44731000
-2.46763400
-0.89587800
-1.47103100
-0.00151500
-0.00200500
-0.00017300
-0.00038200
2.72814400
2.54661100
3.96206100
4.65457700
4.53613400
6.47373200
6.56355200
7.45941400
5.92852100
-2.72828200
-2.54606200
-1.04627200
-2.14221700
-2.18114800
-2.14155600
-2.18007500
-1.04513200
-1.58047000
-1.22026200
-2.76015700
-3.34791200
-3.44842500
-4.54953400
-2.75906500
-3.34609000
-1.57979400
-1.21916700
-3.09381800
-3.93893200
-0.72175800
-0.40868900
-0.03481400
0.91267100
-0.13605000
0.69612300
-1.28950700
-2.02428200
-2.92330300
-1.62394100
-2.27858900
-0.03278900
0.91489300
0.69531400
-0.53905200
-1.58278200
-0.53943100
-1.58338200
0.69465400
2.27212200
3.24452700
1.04970200
1.17820900
0.27505100
-0.16954700
1.04910500
1.17721800
2.27174800
3.24391400
2.03012800
2.86544500
-0.17218600
1.40398000
0.60685700
1.11506400
0.07948200
0.18584600
-0.65567000
-1.77788800
-1.16163200
-2.01838100
-2.69133600
0.60550500
1.11309700