Preparations of sulfido-tricobalt clusters containing pyridyl type ligands: Insertion of carbon monoxide into cobalt-carbon bond

Article abstract of DOI:10.1016/S0022-328X(02)01558-9

The reaction of 2-mercaptopyridine with 1.5 M equivalent of Co₂(CO)₈ in THF at 25 C for 1 h gave a sulfido-tricobalt cluster (PPh₂py) under mild reaction condition afforded a PPh₂py bridged complex (μ₃-S)Co₃ (CO)₅[(μ-C(=O),N-C₅H₄N(C=O)) (μ-P,N-PPh₂py)] (3). The X-ray structure analysis of 3 revealed that a carbonylation process occurred at the Co-C(pyridyl) bond of 1. Carbonylation of 1 at the same position also took place under 1 atm of carbon monoxide at room temperature and formed (μ₃-S) Co₃(CO)₇[(μ-C (=O),N-C₅H₄ N(C=O))] (4). Similar results were obtained in the reaction of 2-quinolinethiol with 1.5 M equivalent of Co₂(CO)₈. A sulfido-tricobalt cluster (μ₃-S)Co₃(CO) ₇(μ-C,N-C₉H₆N) (5) and tris-quinolinethiolate chelated cobalt complex [Co(μ-S,N-SC ₉H₆N)₃](6) were obtained. In contrast to 1, carbonylation did not occur in 5 at 1 atm of carbon monoxide even at 60 C for prolonged reaction hours. However, treatment of 5 with PPh₂py yielded a PPh₂py coordinated (μ₃-S)Co₃(CO)₆[(μ-C, N-C₉H₆N)(PPh₂py)] (7) as the major product, which is accompanied with a small amount of PPh₂py bridged (μ₃-S)Co₃(CO)₅[(μ-C(=O), N-C₉H₆N(C=O))(μ-P, N-PPh₂py)] (8). Carbonylation did occur at the Co-C(quinolinyl) bond of 5, even though less efficient than that of 1, while reacted with a PPh₂py ligand. The same reaction pattern was observed for the reaction of 2-mercapto-nicotinic acid methyl ester with 1.5 M equivalent of Co₂(CO)₈; a sulfido-tricobalt cluster (μ₃-S)Co₃(CO)₇(μ-C, N-C₅H₃NC(=O) OCH₃) (9) was obtained as the major product. The crystal structures of all eight new complexes have been determined.

Full text of DOI:10.1016/S0022-328X(02)01558-9

Journal of Organometallic Chemistry 655 (2002) 172Á181
/
www.elsevier.com/locate/jorganchem
Preparations of sulfido-tricobalt clusters containing pyridyl type
ligands: insertion of carbon monoxide into cobaltÃcarbon bond
/
Fung-E. Hong *, Shu-Chun Chen, Yu-Tain Tsai, Yu-Chang Chang
Department of Chemistry, National Chung-Hsing University, Taichung 40227, Taiwan, ROC
Received 19 March 2002; received in revised form 23 April 2002; accepted 30 April 2002
Abstract
The reaction of 2-mercaptopyridine with 1.5 M equivalent of Co2(CO)8 in THF at 25 8C for 1 h gave a sulfido-tricobalt cluster
(m3-S)Co3(CO)7(m-C,NÃC5H4N) (1). Further reaction of 1 with diphenyl-2-pyridylphosphine (PPh2py) under mild reaction
condition afforded a PPh2py bridged complex (m3-S)Co3(CO)5[(m-C(ÄO),NÃC5H4N(CÄO))(m-P,NÃPPh2py)] (3). The X-ray
structure analysis of 3 revealed that a carbonylation process occurred at the CoÃC(pyridyl) bond of 1. Carbonylation of 1 at the
same position also took place under 1 atm of carbon monoxide at room temperature and formed (m3-S)Co3(CO)7[(m-C(ÄO),NÃ
C5H4N(CÄO))] (4). Similar results were obtained in the reaction of 2-quinolinethiol with 1.5 M equivalent of Co2(CO)8. A sulfido-
tricobalt cluster (m3-S)Co3(CO)7(m-C,NÃC9H6N) (5) and tris-quinolinethiolate chelated cobalt complex [Co(m-S,NÃSC9H6N)3] (6)
were obtained. In contrast to 1, carbonylation did not occur in 5 at 1 atm of carbon monoxide even at 60 8C for prolonged reaction
hours. However, treatment of 5 with PPh2py yielded a PPh2py coordinated (m3-S)Co3(CO)6[(m-C,NÃC9H6N)(PPh2py)] (7) as the
major product, which is accompanied with a small amount of PPh2py bridged (m3-S)Co3(CO)5[(m-C(ÄO),NÃC9H6N(CÄO))(m-P,NÃ
PPh2py)] (8). Carbonylation did occur at the CoÃC(quinolinyl) bond of 5, even though less efficient than that of 1, while reacted
with a PPh2py ligand. The same reaction pattern was observed for the reaction of 2-mercapto-nicotinic acid methyl ester with 1.5 M
equivalent of Co2(CO)8; a sulfido-tricobalt cluster (m3-S)Co3(CO)7(m-C,NÃC5H3NC(ÄO)OCH3) (9) was obtained as the major
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product. The crystal structures of all eight new complexes have been determined. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Sulfido-tricobalt clusters; Mercaptopyridine; CO insertion; Diphenyl-2-pyridylphosphine
1. Introduction
tion of Co2(CO)8 with sulfur-containing compounds, it
is natural for us to pick up mercaptopyridines as
preferred reactants. In this paper, we report a general
route of preparing pyridyl derivatives bridging sulfido-
tricobalt carbonyl clusters from the reactions of various
mercaptopyridines with Co2(CO)8. We will also describe
It has always been a difficult task to search for a
systematic route in stabilizing the paramagnetic sulfido-
tricobalt carbonyl (m3-S)Co3(CO)9 since its first pre-
paration and characterization [1]. One of the most
frequently employed methods is to prepare a diamag-
netic sulfido-tricobalt clusters with the general formula
(m3-S)Co3(CO)7(m-X) (X: a bridging, three-electron do-
nating ligand) [2]. Apparently, most of the sulfido-
tricobalt carbonyl clusters are stabilized by the assis-
tance of those three-electron donating, bridging ligands.
The pyridyl derivatives are chosen as prime candidates
due to their unequivocal bonding capacities as a three-
electron donating, bridging ligands. Since most of the
sulfido-tricobalt clusters were obtained from the reac-
an uncommon carbonylation that took place at the CoÃ
/
C(pyridyl) bond of the sulfido-tricobalt carbonyl cluster
while reacting with external ligands such as CO or
diphenyl-2-pyridylphosphine (PPh2py).
2. Results and discussion
2.1. Reaction of Co2(CO)8 with 2-mercaptopyridine
Reaction of Co2(CO)8 with 2-mercaptopyridine in
THF at 25 8C for 1 h gave two compounds: a new
* Corresponding author. Fax: ꢀ
/
886-4-2862547.
E-mail address: fehong@dragon.nchu.edu.tw (F.-E. Hong).
sulfido-tricobalt cluster (m3-S)Co3(CO)7(m-C,NÃ
/C5H4N)
0022-328X/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 5 5 8 - 9

F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á
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181
173
Scheme 1.
(1) and an known compound, mer-tris(pyridine-2-thio-
lato)cobalt(III) (2) [3] (Scheme 1).
[(m-C(Ä
/
O),NÃ
/
C5H4N(CÄ
/
O))(m-P,NÃ
/
PPh2py)] (3) in
67%. Crystal structure of 3 discloses that a CO
Compound 1 was characterized by spectroscopic
means as well as by X-ray crystal structure determina-
tion (Table 1). The molecular structure of 1 shows that it
is a sulfido-tricobalt carbonyl unit (m3-S)Co3(CO)7 being
bridged by a pyridyl ligand (Fig. 1) [4]. Obviously, the
insertion took place at the CoÃC(pyridyl) bond of 1
/
(Fig. 1). Interestingly, the carbonylation took place at
room temperature without extra CO pressure [6]. The
phosphorus and nitrogen atom of the PPh2py ligand
coordinate to the Co(1) and Co(2), respectively. The
bridged PPh2py ligand is also located at the equatorial
position of the sulfido-tricobalt cluster. It is believed
that the attack of PPh2py ligand towards 1 comes from
the top of the sulfido-tricobalt cluster in order to
prevents severe steric hindrance. As a result, the PPh2py
ligand takes equatorial position in the sulfido-tricobalt
CÃ
ruptured during the formation of 1. A direct CoÃ
covalent bond and a pyridyl coordinated CoÃN bond
/
S and SÃ
/
H bonds of the 2-mercaptopyridine were
/C
/
were formed through the pyridyl ligand. Four atoms,
Co(1), Co(2), C(1), N(1), are almost coplanar. The
bridged pyridyl ligand is located at the equatorial rather
than the axial position of the sulfido-tricobalt cluster.
The pyridyl ligand has to be close to the m3-S in sulfido-
tricobalt cluster, which is at equatorial position, pre-
cluster. The bond length of the pyridyl bridged Co(1)Ã
Co(3) is the shortest among the three cobaltÃcobalt
bonds, which is consistence with 1. All these three bonds
Co bond lengths region [7]. The
/
/
sumably due to the breaking of CÃ
during the formation of cluster. It also shows that the
pyridyl ligand bridged Co(1)ÃCo(2) bond length is the
shortest among all three cobaltÃcobalt bonds. The
lengths of three CoÃS bonds are almost identical (Table
/
S bond of SÃ/C5H4N
are within common CoÃ
/
five atoms Co(1), C(6), C(1), N(1) and Co(3) are almost
coplanar. The facts that the corresponding bond angles
/
/
of Co(1)Ã
C(6)ÃC(1) are 123.8(8), 115.5(9) and 120.8(7)8, respec-
tively, and the bond length for C(6)Ã
all point to the existence of a carbonyl group.
Compound 4,
(m3-S)Co3(CO)7(m-C(Ä
C5H4N(CÄO)), was obtained from the reaction of 1
/
C(6)Ã
/
O(1), C(1)Ã
/
C(6)Ã
/
O(1) and Co(1)Ã
/
/
/
˚
O(1) is 1.523(13) A,
2). The capped sulfur atom donates four electrons in
/
cluster electron count [5].
Further reaction of 1 with PPh2py in THF at 25 8C
for 5 h gave a PPh2py bridged complex (m3-S)Co3(CO)5-
/
O),NÃ
/
/

174
F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á181
/
Table 1
Crystal data of 1, 3Á8 and 9
/
Compound
1
3
4
5
Formula
C
483.01
12H4Co3NO7S
C28H18Co3N2O6PS
718.26
C13H4Co3NO8S
511.02
Triclinic
C16H6Co3NO7S
533.07
Triclinic
Formula weight
Crystal system
Space group
Triclinic
¯
Monoclinic
P2(1)/c
14.927(3)
¯
P1/
¯
P1/
/
P1/
/
/
˚
a (A)
8.4341(18)
9.427(2)
11.557(2)
95.038(4)
100.725(4)
108.548(4)
845.1(3)
2
7.9683(15)
9.856(2)
12.557(2)
77.374(4)
71.848(4)
67.253(4)
858.8(3)
2
8.0896(8)
9.0519(9)
13.7107(14)
75.474(2)
84.961(2)
73.277(2)
930.65(16)
2
˚
b (A)
10.964(2)
18.262(4)
˚
c (A)
a (8)
b (8)
104.085(4)
g (8)
3
V (A )
˚
2899.2(9)
4
Z
Dcalc (Mg mꢁ3
)
1.898
0.71073
3.064
1.646
0.71073
1.868
1.976
0.71073
3.026
1.902
0.71073
2.793
˚
l (MoÁ
m (mmꢁ1
2u Range (8)
/Ka) (A)
)
2.31Á
/
26.04
2.18Á
/
26.08
2.25Á
/
26.02
2.42Á26.00
/
Observed reflections [F ꢀ4s(F)]
Refined parameters
1761
217
1969
370
1887
235
2130
253
a
R1 for significant reflections
wR2 for significant reflections
0.0596
0.1402
0.853
0.0527
0.0932
0.807
0.0622
0.1423
0.899
0.0482
0.1172
0.804
b
c
Goodness-of-fit
6
7
8
9
Formula
C
539.55
27H18CoN3S3
C32H20Co3N2O6PS
768.32
C32H20Co3N2O6PS
768.32
C14H6Co3NO9S
541.05
Triclinic
Formula weight
Crystal system
Space group
Monoclinic
P2(1)/n
10.212(3)
14.894(4)
15.853(4)
Monoclinic
P2(1)/n
Monoclinic
C2/c
31.794(4)
¯
P1/
/
˚
a (A)
12.2792(9)
14.0826(10)
18.9166(14)
8.0578(7)
8.8640(8)
14.1571(13)
79.865(2)
82.106(2)
70.876(2)
936.99(15)
2
˚
b (A)
11.1481(15)
18.686(3)
˚
c (A)
a (8)
b (8)
g (8)
V (A )
Z
94.545(5)
105.0420(10)
108.888(3)
3
˚
2403.7(11)
4
1.491
3159.0(4)
4
6266.5(15)
8
1.629
Dcalc (Mg mꢁ3
)
1.615
0.71073
1.720
1.918
0.71073
2.783
˚
l (MoÁ
m (mmꢁ1
2u Range (8)
/Ka) (A)
0.71073
0.996
0.71073
1.735
)
1.88Á
/
26.43
2.23Á
/
26.02
1.95Á
/
26.04
1.47Á26.04
/
Observed reflections [F ꢀ4s(F)]
Refined parameters
2820
307
4603
406
4297
406
2937
253
a
R1 for significant reflections
wR2 for significant reflections
0.0553
0.1380
0.928
0.0364
0.1012
0.845
0.0932
0.0818
0.950
0.0460
0.1219
0.993
b
c
Goodness-of-fit
a
R1ꢂja (jFojꢁjFcj)/ja Fojj.
wR2ꢂ
/
fa [w(Fo2 ꢁFc2)2=a [w(Fo2)2gg1=2; wꢂ0.10 for 1, 3Á
/
5.
b
Goodness-of-fitꢂ
/
[a w(Fo2 ꢁFc2)2=(Nrflns ꢁNparams)]1=2
:/
c
with 1 atm of CO in THF at 25 8C for 24 h with the
yield of 38%. Carbonylation of 1 took place under 1 atm
of carbon monoxide, nevertheless, which was less
efficient while compared with the previous reaction. It
is seen clearly that the phosphine ligand, PPh2py, played
a vital role in enhancing the reaction rate. The structural
analysis of 4 shows that a CO insertion took place at the
bridging PPh2py ligand, the mainframe of 3 is almost
identical with 4.
The proton chemical shifts of the bridged pyridyl
1
ligand of 1 and 4 were assigned with the aid of HÁ1
/
H
COSY spectra as shown in Fig. 5. The most down-
fielded doublet signal of 1 was assigned to Ha because of
the adjacent electron-withdrawing nitrogen. The most
up-fielded signal is assigned as Hb due to its strong
CoÃ
/
C(pyridyl) bond of 1 (Fig. 1). Except for the

F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á
/
181
175
2.2. Reaction of Co2(CO)8 with 2-quinolinethiol
The reaction of 2-quinolinethiol with Co2(CO)8 was
carried out for the purpose of comparison. Similar
results, a major product, sulfido-tricobalt cluster (m3-
S)Co3(CO)7(m-C,NÃ
relatively small amount of tris-quinolinethiolate che-
lated cobalt complex [Co(m-S,NÃSC9H6N)3] (6), were
/C9H6N) (5), accompanied with a
/
obtained. In contrast to the case of 1, no carbonylation
of 5 was observed at additional one atmospheric
pressure of carbon monoxide even at 60 8C for 16 h,
instead it decomposed. The resistance of CO insertion is
probably due to a stronger bonding between CoÃ
/
C(quinolinyl) in 5. As expected, the crystal structure of
5 reveals that the main framework is quite similar as 1.
The bridged ligand, quinolinyl, is also located at the
equatorial position of the sulfido-tricobalt cluster.
Interestingly, the structure of 6 shows that the three
bridged quinolinethiolate ligands are not arranged in the
same manner as that of 2. Each sulfur atom is in the
trans-position of a corresponding nitrogen atom; 6 is a
facial isomer [8]. The averaged bond length of CoÃ
/
N
˚
S is 1.986 and 2.2728 A, respectively. Com-
and CoÃ
/
plexes 6 could not convert to 5 while reacted with excess
of Co2(CO)8 (Fig. 2).
The reaction of PPh2py with 5 gave a PPh2py
coordinated (m3-S)Co3(CO)6[(m-C,NÃ
(7) as the major product, which is accompanied with a
small amount of PPh2py bridged (m3-S)Co3(CO)5[(m-C(Ä
O),N-C9H6N(CÄO))(m-P,NÃPPh2py)] (8). The structure
/
C9H6N)(PPh2py)]
/
/
/
of 7 shows that the phosphine coordinates to Co(2)
through phosphorous site as a mono-dentate ligand
(Fig. 3). On the contrast, PPh2py acts only as a bridging
ligand in the reaction of 1 with it. The expected CO
insertion occurred at the CoÃ/C(quinolinyl) bond of 8.
Nevertheless, it is much less efficient than in the case of
1 (Fig. 3). The phosphorus and nitrogen atom of the
PPh2py ligand had coordinated to the Co(2) and Co(3),
respectively. This newly bridged PPh2py is also located
at the equatorial position of the sulfido-tricobalt cluster.
The bond length of the pyridyl bridged Co(1)Ã
the shortest among the three cobaltÃcobalt bonds,
which is consistent with that for 1. All these three bonds
Co bond lengths region. The five
atoms Co(1), C(6), C(1), N(1) and Co(3) are almost
coplanar. The facts that the respective bond angles of
/
Co(3) is
/
Fig. 1. Molecular structures of: (a) (m3-S)Co3(CO)7(m-C,NÃ
(1); (b) (m3-S)Co3(CO)5[(m-C(ÄO),NÃC5H4N(CÄO))(m-P,NÃPPh2py)]
(3); (c) (m3-S)Co3(CO)7[(m-C(ÄO),NÃC5H4N(CÄO))] (4).
/
C5H4N)
are within usual CoÃ
/
/
/
/
/
/
/
/
123.7(3), 114.8(3) and 121.4(3)8 for Co(1)Ã
C(1)ÃC(6)ÃO(1) and Co(1)ÃC(6)ÃC(1) and the bond
O(1) all support the fact
/
C(6)Ã
/
O(1),
correlation with Ha. The remaining doublet and doublet
of doublet signals are assigned as Hd and Hc, respec-
tively. Slightly different patterns of the bridged pyridyl
ligands were observed for 4 and 1 in 1H-NMR. It seems
that the corresponding doublet signal of Hd has a
notable up-fielded shift from 1 to 4. This large up-
fielded shift might be caused by the neighboring
carbonyl group. The relative positions of the three
protons, Ha, Hc, Hb, are remained the same.
/
/
/
/
˚
length of 1.529(5) A for C(6)Ã
/
of the existence of a carbonyl group.
2.3. Reaction of Co2(CO)8 with 2-mercapto-nicotinic
acid methyl ester
A reaction was carried out between 2-mercapto-
nicotinic acid methyl ester, mercaptopyridine with a

176
F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á181
/
Table 2
Comparison of selected structural parameters of 1, 3Á
/
5, 7, 8 and 9
1
3
4
5
7
8
9
˚
Bond lengths (A)
SÃCo(1)
SÃCo(2)
SÃCo(3)
2.151(2)
2.157(2)
2.151(3)
2.5427(6)
2.5350(15)
2.4141(17)
1.952(7)
1.963(8)
1.316(11)
2.158(3)
2.175(3)
2.169(3)
2.135(2)
2.188(2)
2.154(2)
2.1405(19)
2.1671(18)
2.1703(19)
2.5425(13)
2.5658(12)
2.4185(12)
1.934(6)
2.1512(10)
2.1659(9)
2.1839(9)
2.5633(6)
2.5508(6)
2.4467(6)
1.937(3)
2.1550(10)
2.1892(10)
2.1752(11)
2.5188(8)
2.5403(7)
2.4558(7)
2.1510(12)
2.1642(12)
2.1531(11)
2.5402(8)
2.5591(8)
2.4182(7)
1.948(4)
Co(1)ÃCo(2)
Co(2)ÃCo(3)
Co(3)ÃCo(1)
Co(1)ÃC(1)
Co(3)ÃN(1)
C(1)ÃN(1)
Co(1)ÃC(6)
C(1)ÃC(6)
PÃCo(2)
2.5224(19)
2.5263(19)
2.4460(19)
2.5417(16)
2.5358(16)
2.4420(15)
1.967(8)
1.363(12)
1.923(10)
1.523(13)
2.155(3)
2.021(8)
2.002(6)
1.367(10)
1.917(9)
1.495(12)
1.982(5)
1.323(8)
1.999(3)
1.319(4)
2.042(3)
1.339(5)
1.901(4)
1.529(5)
2.1602(11)
2.031(3)
1.967(4)
1.347(5)
2.2206(9)
N(2)ÃCo(1)
Bond angles (8)
Co(1)ÃC(1)ÃN(1)
C(1)ÃN(1)ÃCo(3)
N(1)ÃCo(3)ÃCo(1)
Co(3)ÃCo(1)ÃC(1)
Co(3)ÃCo(1)ÃC(6)
Co(1)ÃC(6)ÃC(1)
Co(1)ÃCo(2)ÃP
105.9(6)
106.7(6)
73.3(3)
74.2(2)
110.3(4)
102.3(4)
74.80(15)
72.64(19)
110.6(2)
102.8(2)
74.00(8)
72.62(10)
106.8(3)
104.8(2)
74.18(9)
73.97(11)
120.6(7)
91.3(3)
121.1(6)
89.1(2)
117.2(2)
91.39(9)
89.0(3)
120.8(7)
87.09(9)
98.6(2)
90.7(3)
119.9(6)
89.15(11)
121.4(3)
86.18(3)
99.21(9)
107.56(3)
5.2
Co(2)ÃCo(1)ÃN(2)
Dihedral angles (8)
a
Plane1ÃPlane2
9.0
18.2
18.3
14.4
9.5
17.9
17.8
10.6
Plane2ÃPlane3
a
Plane 1: Co(1), Co(3), N(1), C(1); Plane 2: Co(1), Co(2), Co(3); Plane 3: Co(1), Co(2), P, N(2).
Fig. 2. Molecular structures of [Co(m-S,NÃSC9H6N)3] (6).
/

F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á
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181
177
3. Summary
Several pryidyl derivatives bridged sulfido-tricobalt
carbonyl clusters were prepared through the reaction of
mercaptopyridines with Co2(CO)8. Intramolecular CO
insertion took place at the CoÃ
/
C(pryidyl) bond of 1 or
the CoÃC(quinolinyl) bond of 5 under a rather mild
/
condition in the presence of the bidentate ligand,
PPh2py. The carbonylation of 1 also took place, with
less efficiency, under 1 atm of carbon monoxide.
Contrast to the willingness for CO insertion at the
CoÃ
/
C(pryidyl) bond of 1, carbonylation of 5 at the CoÃ
/
C(quinolinyl) bond requires the additional bidentate
ligand like PPh2py.
4. Experimental
4.1. General
All operations were performed in a nitrogen flushed
glove box or in a vacuum system. Freshly distilled
solvents were used. All processes of separations of the
products were performed by Centrifugal Thin Layer
Chromatography (CTLC, Chromatotron, Harrison
1
model 8924). H-NMR spectra were recorded (Varian
VXR-300S spectrometer) at 300.00 MHz; chemical
shifts are reported in ppm relative to internal Me4Si.
31P- and 13C-NMR spectra were recorded at 121.44 and
1
75.46 MHz, respectively. Some other H-NMR spectra
were recorded at Gemini-200 spectrometer at 200.00
MHz or Varian-400 spectrometer at 400.00 MHz.COSY
spectra: standard pulse sequence, acquisition time 0.213
s, pulse width 21 ms, relaxation delay 1 s, 128 scans, 256
increments. IR spectra of solution in CH2Cl2 were
recorded on a Hitachi 270-30 spectrometer. Mass
spectra were recorded on JOEL JMS-SX/SX 102A
GC/MS/MS spectrometer. Elemental analyzes were
recorded on Heraeus CHNÃ
/
OÃ
/
SÃ
/
Rapid. Accurate
elemental analyzes were precluded for some of the
following compounds probably due to their chemical
labilities.
Fig. 3. Molecular structures of: (a) (m3-S)Co3(CO)7(m-C,NÃ
(5); (b) (m3-S)Co3(CO)6[(m-C,NÃC9H6N)(PPh2py)] (7); (c) (m3-
S)Co3(CO)5[(m-C(ÄO),NÃC9H6N(CÄO))(m-P,NÃPPh2py)] (8).
/
C9H6N)
/
/
/
/
/
4.1.1. Synthesis of Co3(CO)7(m3-S)(m-C,NÃ
/
C5H4N)
(1)
Into a 100 cm3 flask was placed a solution of
Co2(CO)8 (0.60 g, 0.175 mmol) and 2-mercaptopyridine
(0.195 g, 1.75 mmol) in 20 cm3 THF. The solution was
stirred at 25 8C for 1 h. Subsequently, the solvent of the
resulting red solution was removed and the residue was
chromatographed by CTLC. The first brown band of
strong electron-withdrawing group, and Co2(CO)8, for
the purpose of comparison [9]. Contrast to the previous
reaction, only the sulfido-tricobalt cluster (m3-
S)Co3(CO)7(m-C,NÃ
/
C5H3NC(Ä
/O)OCH3) (9) was ob-
tained. There was no sign of the presence of tris-pyridyl
chelated cobalt complex. Crystal structure of 9 shows
the main framework of it is quite similar to 1 or 5. The
bridged ligand is also located at the equatorial position
of the sulfido-tricobalt cluster. Some structural para-
meters of compound 1, 3, 4, 5, 7, 8 and 9 are selected
and listed in Table 2 for comparison (Fig. 4).
the title compound Co3(CO)7(m3-S)(m-C,NÃ
/
C5H4N)
(0.1381 g, 0.268 mmol) with 16% yield was separated
out.
Complex 1: Brown crystalline solid; 1H-NMR
(CD2Cl2, d, ppm): 7.74 (d, 1H, JHÃH
ꢂ2.60 Hz), 7.35
/

178
F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á181
/
Fig. 4. Molecular structure of (m3-S)Co3(CO)7(m-C,NÃ
/
C5H3NC(ÄO)OCH3) (9).
/
(d, 1H, JHÃH
ꢂ
/
8.80 Hz), 7.00 (dd, 1H), 6.63 (dd, 1H);
4.1.2. Synthesis of (m3-S)Co3(CO)5[(m-C(Ä
C5H4N(CÄO))(m-P,NÃPPh2py) (3)
In a dry box, PPh2py (0.152 g, 0.58 mmol) and 1
(0.2800 g, 0.58 mmol) were placed in a 100 cm3 flask
with 20 cm3 THF. The solution was stirred at 25 8C for
/
O),NÃ
/
13C-NMR: 154.92 (s, 1C), 137.44 (s, 1C), 132.52 (s, 1C),
/
/
120.87 (s, 1C); IR (CH2Cl2, cmꢁ1): n(CO)
2035 (s), 2007 (s); MS (FAB): 483 [Mꢀ].
ꢂ2081 (m),
/
Fig. 5. 1HÁ1
H COSY spectra of the bridged pyridyl of 1 (left) in CDCl3 (400 MHz) and 4 (right) in CD2Cl2 (300 MHz).
/

F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á
/
181
179
5 h. Subsequently, the solvent of the resulting brown
solution was removed and the residue was chromato-
tographed by CTLC. The first band, brown in color of
C9H6N) (5)
(0.4635 g, 0.8695 mmol) was eluted out by C6H14. The
the compound (m3-S)Co3(CO)7(m-C,NÃ
/
graphed by CTLC in a CH2Cl2Á
/
C6H14ꢂ/1:1 mixed
solvent. The second band, brown in color of the title
compound 3 (0.282 g, 0.392 mmol) was obtained. The
yield is 67%.
yield is 70%. A small amount of greenish brown [Co(m-
S,NÃ
solvent of MeOHÁ
Complex 5: Brown crystalline solid; 1H-NMR
(CD2Cl2, d, ppm): 7.399Á
7.731 (m, 6H, arene); 13C-
/SC9H6N)3] (6) was eluted out by the mixture
/
CH2Cl2ꢂ1/2.
/
Complex 3: Brown crystalline solid; 1H-NMR
(CD2Cl2, d, ppm): 9.55 (d, 1H, JHÃH
(d, 1H, JHÃH 2.2 Hz), 7.74 (m, 2H), 7.44Á
10H), 7.21Á7.00 (m, 3H), 6.63 (d, 1H, JHÃH
13C-NMR: 162.98 (s, 1C, PPh2Py), 156.07 (d, 1C, JPC
13.0 Hz, py), 155.37 (s, 1C, PPh2Py), 137.87 (s, 1C, Py),
136.83 (s, 1C, PPh2Py), 135.68 (d, 1C, JPC 30, ipso of
arene), 135.30 (d, 1C, JPC 40 Hz, ipso of arene), 133.77
(d, 2C, JPC 12.3 Hz, arene), 131.55 (d, 2C, JPC 10.8
Hz, arene), 130.88 (s, 1C, p-arene), 130.29 (s, 1C, Py),
130.39 (s, 1C, p-arene), 129.0Á129.2 (m, 4C, arene),
ꢂ
/
4.8 Hz), 8.37
7.57 (m,
6.4 Hz);
/
ꢂ
/
/
NMR (CDCl3): 122.91, 125.56, 127.42, 128.93, 130.32,
130.89, 133.38, 148.30 (arene); IR (KBr, cmꢁ1): 2009
(s), 2080 (s); Anal. Calc. for 5: C, 36.05; H, 1.13; N, 2.63.
Found: C, 36.47; H, 1.26; N, 2.22%.
/
ꢂ
/
ꢂ
/
ꢂ
/
Complex 6: Greenish brown crystalline solid; 1H-
ꢂ
/
NMR (CD2Cl2, d, ppm): 8.83 (d, JHÃH
arene), 8.32 (d, JHÃH 8.80 Hz, arene), 8.21 (d,
JHÃH 8.80 Hz, arene), 7.87 (d, JHÃH 8.20 Hz, arene),
ꢂ
/
8.20 Hz,
ꢂ
/
ꢂ
/
ꢂ
/
ꢂ
/
ꢂ
/
/
7.74 (dd, 1H, arene), 7.56 (dd, 1H, arene); 13C-NMR
(CDCl3): 156.12, 147.81, 136.67, 129.81, 129.47, 128.34,
127.57, 126.87, 119.35 (arene).
126.7 (s, 1C, PPh2Py), 125.38 (s, 1C, Py), 115.63 (s, 1C,
Py); 31P-NMR (CDCl3): 46.9 (s); IR (KBr, cmꢁ1):
n(CO)
[Mꢀ]; Anal. Calc. for 3: C, 46.82; H, 2.52; N, 3.90.
Found: C, 45.62; H, 3.89; N, 3.86%.
ꢂ1577 (w), 1978 (s), 2030 (s); MS (FAB): 719
/
4.2.1. Synthesis of (m3-S)Co3(CO)6
[(m-C,NÃ
(m3-S)Co3(CO)5[(m-C(Ä
(m-P,NÃPPh2py)] (8)
/
C9H6N)(PPh2py)] (7) and
/
O),NÃC9H6N(CÄ
/
/O))-
/
4.1.3. Synthesis of (m3-S)Co3(CO)7[(m-C(Ä
/
O),NÃ
/
Following the same procedures, 0.588 mmol (0.3134
g) of 5 and molar equivalent of PPh2py (0.1548 g, 0.588
mmol) were dissolved in 5 cm3 of THF each, then were
transferred into a 100 cm3 flask. The solution was stirred
at 25 8C for 1 h. Subsequently, the solvent of the
resulting dark brown solution was removed and the
C5H4N(CÄ
/
O))] (4)
Into a 100 cm3 flask was placed 1 (0.314 g, 0.652
mmol) with a jointed balloon. THF (20 cm3) was added
and the solution was stirred at 25 8C for 24 h.
Subsequently, the solvent of the resulting brown solu-
tion was removed and the residue was chromatographed
residue was chromatographed by CTLC in a CH2Cl2Á
/
by CTLC in a CH2Cl2Á
/
C6H14ꢂ
/
1:1 mixed solvent. First
brown band which was nothing but unreacted 1 (51%)
C6H14ꢂ1:1 mixed solvent. The first band, dark brown
/
in color of the title compound 7 (0.3038 g, 0.396 mmol)
was obtained. The yield is 67%. A small amount of the
brown compound was eluted by CH2Cl2 as the second
band and was characterized as 8.
was collected. The second orange band of the title
compound (m3-S)Co3(CO)7[(m-C(Ä
/
O),NÃ
/
C5H4N(CÄ/O))
(0.1264 g, 0.247 mmol) with 38% yield was separated
out.
1
Complex 7: Dark brown crystalline solid; H-NMR
Complex 4: Orange crystalline solid; 1H-NMR
(CDCl3, d, ppm): 8.79 (d, 1H, py), 7.26Á
arene); 13C-NMR (CD2Cl2): 160.26 (d, JPC
1C, py), 150.16 (d, JPC 15.8 Hz, 1C, py), 148.17 (s, 1C,
arene), 135.70 (d, JPC 7.3 Hz, 1C, py), 134.87 (d,
JPC 42.1 Hz, 1C, ipso), 134.54 (d, JPC 42.8 Hz, 1C,
/7.68 (m, 19H,
(CD2Cl2, d, ppm): 8.31 (d, 1H, JHÃH
(dd, 1H), 7.21 (dd, 1H), 7.10 (d, 1H, JHÃH
13C-NMR: 217.99 (s, 1C, CÄ
O), 163.24 (s, 1C, py),
155.97 (s, 1C, py), 139.13 (s, 1C, py), 128.21 (s, 1C, py),
118.50 (s, 1C, py); IR (KBr, cmꢁ1): 1635 (m), 1980 (m),
2033 (s), 2083 (m); MS (FAB): 511 [Mꢀꢁ
6CO]; Anal.
Calc. for 4: C, 30.55; H, 0.79; N, 2.74. Found: C, 30.64;
H, 0.94; N, 2.75%.
ꢂ/4.40 Hz), 7.64
ꢂ
/
64.7 Hz,
ꢂ/7.20 Hz);
ꢂ
/
/
ꢂ
/
ꢂ
/
ꢂ
/
ipso); 133.64 (s, arene), 133.51 (s, 2C, Ph), 133.39 (s, 2C,
Ph), 130.28 (s, 1C, arene), 129.82 (s, 2C,Ph), 129.63 (s,
1C, arene), 128.63 (s, 1C, arene), 128.36 (s, 2C, Ph),
128.28 (s, 2C, Ph), 127.87 (s, 1C, py), 127.15 (s, 1C,
arene), 124.89 (s, 1C, arene), 123.53 (s, 1C, py), 123.26
(s, 1C, arene); 31P-NMR (CDCl3): 48.86; Anal. Calc. for
7: C, 50.02; H, 2.62; N, 3.65. Found: C, 52.55; H, 4.42;
/
4.2. Reaction of 2-quinolinethiol with Co2(CO)8
N, 3.62%; IR (KBr, cmꢁ1): n(CO)
1].
ꢂ1980.3 (s), 2014.3 (s);
/
Similar processes were undertaken as in the prepara-
tion of 1. Into a 100 cm3 flask was placed a solution of
Co2(CO)8 (0.6360 g, 1.86 mmol) and 2-quinolinethiol
(0.200 g, 1.24 mmol) in 25 cm3 THF and was stirred at
25 8C for 1 h. Subsequently, the solvent of the resulting
red solution was removed and the residue was chroma-
MS (FAB): 769 [Mꢀꢀ
/
Complex 8: Brown crystalline solid; 1H-NMR
(CDCl3, d, ppm): 9.60 (d, 1H, Py), 8.90 (d, 1H, arene),
8.06 (d, 1H, arene), 6.69Á
NMR: 36.57; IR (KBr, cmꢁ1): n(CO)
(s), 2013.6 (s); MS (FAB): 769 [Mꢀꢀ
/
7.83 (m, 17H, arene); 31P-
1575.2 (s), 1979.3
1]. Elemental
ꢂ
/
/

180
F.-E. Hong et al. / Journal of Organometallic Chemistry 655 (2002) 172Á181
/
analysis and 13C-NMR for 8 were precluded due to its
small quantity.
Data Center, CCDC no. 176592Á
1, 3Á9, respectively. Copies of this information may be
obtained free of charge from the Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (Fax: ꢀ44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
/
176599 for compounds
/
4.2.2. Synthesis of (m3-S)Co3(CO)7(m-C,NÃ
/
/
C5H3NC(ÄO)OCH3) (9)
/
Compound 9 was prepared by the same procedures
adapted from the synthesis of 1. Into a 100 cm3 flask
was placed 2-mercapto-nicotinic acid methyl ester (0.200
g, 1.182 mmol) with 1.5 M equivalent of Co2(CO)8
(0.606 g, 1.733 mmol) in 10 cm3 THF. The solution was
stirred at 0 8C for half an hour then it was allowed to
warm up to 25 8C for another 30 min. Subsequently,
the solvent of the resulting dark brown solution was
removed and the residue was chromatographed by
CTLC. The second brown band of the title compound
Acknowledgements
We are grateful to the National Science Council of the
R.O.C. (Grant NSC 90-2113-M-005-021) for financially
supporting this research.
(m3-S)Co3(CO)7(m-C,NÃ
/
C5H3NC(Ä
/
O)OCH3)
(9)
(0.1537 g, 0.2840 mmol) with 24% yield was separated
out. A large amount of the decomposed materials
remains uncharacterized.
Complex 9: Brown crystalline solid; 1H-NMR
References
[1] (a) L. Marko´, G. Bor, E. Klumpp, Chem. Ind. (Lond.) (1961)
1491;
(CDCl3, d, ppm): 7.86 (d, 1H, JHÃH
7.71 (d, 1H, JHÃH 7.5 Hz, py), 6.68 (dd, 1H, py), 3.98
(s, 3H,CH3); 13C-NMR: 166.97 (s, 1C, CÄ
O), 156.99 (s,
O), 135.31 (s, 1C, CH),
119.52 (s, 1C, CH), 52.33 (s, 1C, CH3); Anal. Calc. for 9:
C, 31.08; H, 1.12; N, 2.59. Found: C, 31.29; H, 1.34; N,
ꢂ
/
4.8 Hz, py),
(b) C.H. Wei, L.F. Dahl, Inorg. Chem. 6 (1967) 1229;
(c) C.E. Strouse, L.F. Dahl, Discuss. Faraday Soc. 47 (1969)
93;
ꢂ
/
/
(d) C.E. Strouse, L.F. Dahl, J. Am. Chem. Soc. 93 (1971)
6032.
1C, CH), 138.19 (s, 1C, CCÄ
/
[2] (a) S. Vastag, G. Gerbasio, D. Marabello, G. Szalomtai, L. Marko´,
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2.23%; IR (KBr, cmꢁ1): n(CO)
ꢂ
/
2084 (s), 2038 (s), 1726
(m), 1555 (m), 1392 (m), 1275 (m); MS (FAB): 512
[Mꢀꢁ
CO].
(b) L. Marko´, G. Bor, E. Klumpp, Chem. Ber. 100 (1967) 1451;
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/
(e) L. Marko´, G. Bor, E. Klumpp, B. Marko´, G. Alma´sy, Chem.
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5. X-ray crystallographic studies
Suitable crystals of 1, 3Á8 and 9 were sealed in thin-
(g) B. Zhuang, P. Yu, L. Huang, L. He, G. Pan, Polyhedron 16
(1997) 1425;
/
walled glass capillaries under nitrogen atmosphere and
mounted on a Bruker AXS SMART 1000 diffract-
ometer. Intensity data were collected in 1350 frames
with increasing v (width of 0.38 per frame). The
absorption correction was based on the symmetry
equivalent reflections using SADABS program. The space
group determination was based on a check of the Laue
symmetry and systematic absences, and was confirmed
using the structure solution. The structure was solved by
direct methods using a SHELXTL package. All non-H
atoms were located from successive Fourier maps and
hydrogen atoms were refined using a riding model.
Anisotropic thermal parameters were used for all non-H
atoms, and fixed isotropic parameters were used for H
(h) E.I. Stiefel, K. Matsumoto, Transition Metal Sulfur Chemistry:
Biological and Industrial Significance, ACS, Washington DC,
1996.
[3] (a) E.C. Constable, C.A. Palmer, D.A. Tocher, Inorg. Chim. Acta
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(b) E. Block, H. Kang, G. Ofori-Okai, J. Zubieta, Inorg. Chim.
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(c) C. Fielding, S. Parsons, R.E.P. Winpenny, Acta Crystallogr.
Sect. C 53 (1997) 174;
(d) Interestingly, 2 also obtained as the major product in the
reaction of Co2(CO)6(m-HCÅCSiMe3) with 2-mercaptopyridine.
/
[4] Several related works were reported: (a) J.J. Schneider, Chem. Ber.
128 (1995) 321;
(b) C.P. Lenges, P.S. White, W.J. Marshall, M. Brookhart,
Organometallics 19 (2000) 1247;
(c) C. Mahe, H. Patin, J.-Y. Le Marouille, A. Benoit, Organome-
tallics 2 (1983) 1051;
atoms. Crystallographic data of 1, 3Á8 and 9 are
/
(d) A. Benoit, A. Darchen, J.-Y. Le Marouille, C. Mahe, H. Patin,
Organometallics 2 (1983) 555.
summarized in Table 1.
[5] D.M.P. Mingos, Nat. (Lond.) Phys. Sci. 236 (1972) 99.
[6] A recent report appeared on CO insertion into Co-arene bond
taking place under 1 bar of CO atmosphere. H.-F. Klein, S.
Schneider, M. He, U. Floerke, H.-J. Haupt, Eur. J. Inorg. Chem.
(2000) 2295.
6. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
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Organic Molecules (Chapter 8.7), University Science Books, Mill
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¨ ¨