Preparation and characterization of cobalt-containing alcohols and diols

Article abstract of DOI:10.1016/j.poly.2007.01.037

A series of cobalt-containing alcohols and diols were prepared and characterized. Intramolecular hydrogen-bonding was observed for the cobalt-containing diols [Co₂(CO)₆(μ-η-(HO)R₁R₂CC{triple bond, long}CCR₁

Full text of DOI:10.1016/j.poly.2007.01.037

Polyhedron 26 (2007) 2987–2996
www.elsevier.com/locate/poly
Preparation and characterization of cobalt-containing
alcohols and diols
Jian-Cheng Lee, Yu-Chang Chang, Yi-Jung Ho, Kang-Ming Chu,
*
Hsueh-Liang Chen, Fung-E Hong
Department of Chemistry, National Chung Hsing University, Taichung 40227, Taiwan
Received 10 November 2006; accepted 31 January 2007
Available online 4 February 2007
Abstract
A series of cobalt-containing alcohols and diols were prepared and characterized. Intramolecular hydrogen-bonding was observed for
the cobalt-containing diols [Co2(CO)6(l-g-(HO)R1R2CC„CCR1R2(OH)] (1: R1 = CH3, R2 = C2H5; 2: R1 = CH3, R2 = C3H7),
[Co2(CO)6(l-g-(HO)Ph2CC„CCPh2(OH)] (3) and [(l-PPh2CH2PPh2)Co2(CO)4(l-g-(HO)Ph2CC„CCPh2(OH)] (4). Potentially all
the four compounds could serve as chelating O,O-ligands. In principle, it is possible for compounds [(l-PPh2NHPPh2)Co2(CO)4(l-g-
HC„CCPh2OH)] (5b), [Co2(CO)6(l-g-HC„CC2H4OH] (6) and [Co2(CO)6(l-g-HC„CC3H6OH)] (7) in their syn-conformations to
behave as chelating O,N-ligands. To the best of our knowledge, compounds 5b, 6 and 7 are the first reported examples of
PPh2NHPPh2-bridged dicobalt complexes.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Cobalt-containing diols; Cobalt-containing alcohols; Alkyne-bridged dicobalt complex; Dppm; PPh2NHPPh2
1. Introduction
general methods of preparation of cobalt-containing
mono- or bidentate phosphine ligands has been estab-
lished in our previous studies (Scheme 1) [4]. It has also
been revealed that ligands of this type can be character-
ized as authentic phosphine ligands with bulky, and, in
some cases, electron-rich, character [4b]. Moreover, some
of the palladium complexes with type II ligands have
been demonstrated to perform as effective catalysts in
the renowned Suzuki reactions [5].
Alcohols or diols are readily accessible precursors of
alkoxides. The alkoxy ligands have been long known to
stabilize metals in high oxidation states [6]. Metal alkoxides
are also of great interest due to their current and potential
uses in catalysis. For example, Al(OiPr)3 has been widely
used as a catalyst in organic synthesis as well as in the
ring-opening polymerization of aliphatic cyclic esters [7].
Numerous organic alkoxides as well as their metal-contain-
ing counterparts were prepared. Their chemical reactivities
toward metals were thoroughly examined. Much rich
chemistry of the letter were demonstrated [8]. Herein, we
Alkynes are highly reactive building blocks in organic
synthesis. The fact that alkyne-bridged dicobalt system
has been studied extensively is in part due to its indisput-
able role played in the Pauson–Khand reaction [1]. Com-
plexes of this class are usually obtained from the direct
reaction of dicobalt octacarbonyl (Co2(CO)8) with alky-
nes [2]. The bridging alkyne makes use of both sets of
filled p- and unfilled p*-orbitals in bonding to the dico-
balt framework. The former set is responsible for dona-
tion of the electron-density to the metal center;
meanwhile, the latter one accepts the electron-density
from the metal through back-bonding [3]. This synergetic
effect enhances the rigidity of the Co2C2 core. The char-
acter and reactivity of the bridging alkyne is significantly
changed after the coordination to the metal moiety. A
*
Corresponding author.
E-mail address: fehong@dragon.nchu.edu.tw (F.-E. Hong).
0277-5387/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2007.01.037

2988
J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
O
O
O
O
C
C
C
C
+
Ph2P
PPh2
O
C
O
C
C
Co
Co
(OC)2Co
Ph2P
Co(CO)2
C
C
PPh2
O
C
O
O
O
I
R1
C
R2
IIa: R1=PPh2, R2=PPh2
IIb: R1=PPh2, R2=Ph
IIc: R1=PPh2, R2=Py
IIe: R1=P(tBu)2, R2=Py
IIf: R1=P(tBu)2, R2=Ph
IIg: R1=P(iPr)2, R2=Ph
IIh: R1=P(Cy)2, R2=Ph
C
CR2
1
+
R C
(OC)2Co
Ph2P
Co(CO)2
PPh2
IId: R1=PPh2, R2=Cy
II
Scheme 1.
report the preparation and characterization of a series of
cobalt-containing alcohols and diols using a methodology
similar to the one shown in Scheme 1.
type is a tetrahedron where the alkyne unit is almost per-
pendicular to the metal-metal bond. The structure also
shows that the acetylenic ligands fold in upon coordina-
tion to the cluster core. The distance between the oxygen
˚
2. Results and discussion
and hydrogen atoms of two hydroxyl groups are 2.052 A
for 1, which is well within the intramolecular hydrogen-
1
2.1. Preparation of cobalt-containing diols
bonding range [10]. The H and 13C NMR spectra of 1
are trivial. In contrast with the observed two non-
equivalent hydroxyl protons in solid state, two hydroxyl
protons are equivalent on the NMR timescale giving rise
The room temperature reaction of (HO)R1R2CC„
CCR1R2(OH) with Co2(CO)8 in toluene furnished [Co2-
(CO)6(l-g-(HO)R1R2CC„CCR1R2(OH)] (1: R1 = CH3,
R2 = C2H5; 2: R1 = CH3, R2 = C3H7) in good yields in
4 h (Scheme 2). Compounds 1 and 2 were characterized
by spectroscopic means as well as by single-crystal X-ray
diffraction. The molecular structures of both compounds
revealed a pseudo-tetrahedral Co2C2 core typical for an
alkyne-bridged dicobalt complex (Table 1, Figs. 1 and 2).
Both substituents of the alkyne are bent away from the
dicobalt moiety, as predicted by Dewar–Chatt–Duncan-
son’s model, and reside on the same side [9]. In this regard,
1 and 2 can be considered as potentially chelating metal-
containing diols.
1
to a broad signal at 2.99 ppm in H NMR in CDCl3. In
the structure of 2, the C(2)–C(1)–C(3) and C(1)–C(2)–
C(8) angles are 137.5(2)° and 136.9(2)°, respectively.
The C–C bond distance of the bridged alkyne is
˚
˚
1.324(3) A. The Co–Co bond distance is 2.4639(5) A.
The distance between oxygen atoms of the two hydroxyl
˚
groups are 2.637 A for 2 (Table 1, Fig. 2). Again, in
solution two hydroxyl protons are equivalent and give
rise to a broad signal at 2.98 ppm in 1H NMR in
CDCl3.
As seen above, the two hydroxyl groups of the coordi-
nated alkyne come closer in a well-defined rigid geometry
in these alkyne dinuclear clusters. This observable fact sug-
gests that any charged functional groups at these positions
will be disposed in a clamp-like fashion and are potentially
capable of binding ions of the opposite charge [11]. Unfor-
tunately, attempts to isolate the expected aluminum com-
plexes were not successful (Scheme 3). The reactions of
both 1 and 2 with trimethyl aluminum always led to precip-
itation of compounds of unknown composition. Besides,
the complex would undergo an elimination reaction in
acidic medium and produce the related olefinic compounds
[12].
All carbonyl ligands of compound 1 and other cobalt-
containing alcohols and diols mentioned below are in ter-
minal positions. The C(1)–C(2)–C(3) and C(2)–C(1)–C(7)
angles are 138.6(4)° and 139.6(3)°, respectively, deviated
from the 180° angle characteristic of their free states as
predicted. The C–C bond distance of the bridging alkyne
˚
is 1.341(5) A, which is within the regular double bond
˚
range. The Co–Co bond distance is 2.472 A, which is
comparable to alkyne-bridging dicobalt complex reported
earlier (Table 1, Fig. 1). In general, the cluster core
‘‘–Co2(–C„C–)’’ of a common dicobalt complex of this
Subsequently, the heating Co2(CO)8 with (HO)Ph2-
CC„CCPh2(OH) in toluene at 60 °C for 3 h produced
[Co2(CO)6(l-g-(HO)Ph2CC„CCPh2(OH)] (3). Further
reaction of 3 with PPh2CH2PPh2 (dppm) in toluene at
100 °C for 16 h yielded [(l-PPh2CH2PPh2)Co2(CO)4(l-g-
(HO)Ph2CC„CCPh2(OH)] (4) (Scheme 4). In several
occasions, the bridging dppm is a necessity, especially when
the reaction is conducted at elevated temperatures.
Without the protection provided by the bridging dppm,
intermolecular attacks among Co2(CO)6(l-g-RC„CR)
H
H
C
O
C
O
C
R1
R2
R1
R2
HO
R1
OH
R1
Co2(CO)8
C
+
C C C C
R2
R2
(OC)3Co
Co(CO)3
1: R1=CH3, R2=C2H5
2: R1=CH3, R2=C3H7
Scheme 2.

Table 1
Crystal data of 1, 2, 3, 5a, 5b, 6, and 7
Compound
1
2
3
5a
5b
6
7
Formula
C
912.36
32H36Co4O16
C18H22Co2O8
484.22
C68H44Co4O16
1352.75
C21H12Co2O7
494.17
triclinic
C43H33Co2NO5P2
823.50
C62H50Co4N2O10P4
1342.64
triclinic
C64H54Co4N2O10P4
1370.69
orthorhombic
Pbca
17.6826(12)
20.3498(13)
34.949(3)
Formula weight
Crystal system
Space group
monoclinic
P2ð1Þ=c
monoclinic
P2ð1Þ=c
monoclinic
P2ð1Þ=c
monoclinic
P2ð1Þ=c
ꢀ
ꢀ
P1
P1
˚
a (A)
9.7269(7)
32.247(2)
12.6768(9)
8.9360(9)
11.0808(11)
22.386(2)
15.3065(13)
20.3771(17)
20.1655(17)
6.6972(8)
10.9974(7)
17.5744(12)
20.1312(14)
11.1751(10)
16.5038(15)
18.1966(17)
100.689(2)
105.976(2)
98.860(2)
12576.0(15)
2
1.441
0.71073
1.214
1.53–26.03
11979
747
˚
b (A)
10.8070(13)
14.9215(17)
104.299(2)
98.911(2)
˚
c (A)
a (°)
b (°)
c (°)
91.1600(10)
90.850(2)
101.572(2)
102.9600(10)
3
˚
V (A )
3975.5(5)
4
1.585
0.71073
3.416
2.04–25.99
7787
2216.4(4)
4
1.451
0.71073
1.534
1.82–26.02
4353
6161.8(9)
4
1.458
0.71073
1.128
1.44–26.01
12080
809
1008.7(2)
2
1.627
0.71073
1.685
1.99–25.99
3918
3094.8(5)
4
1.443
0.71073
1.006
1.56–26.04
7465
Z
8
Dc (Mg/m3)
1.448
0.71073
1.197
1.63–25.99
12344
757
0.0461
0.0827
0.808
˚
k (Mo Ka) (A)
l (mmꢀ1
)
h Range (°)
Observed reflections (F > 4r(F))
Number of refined parameters
aR1 for significant reflections
bwR2 for significant reflections
cGoodness-of-fit
469
253
271
478
0.0459
0.1139
0.995
0.0411
0.0993
1.019
0.0393
0.0872
0.927
0.0437
0.1071
0.949
0.0408
0.0791
0.901
0.0502
0.1306
0.981
P
P
a
b
c
R1 = j (jFoj ꢀ jFcj)/j Foi.
P
P
2
2
wR2 ¼ f ½wðF 2o ꢀ F c2Þꢁ = ½wðF 2oÞ ꢁg1=2; w = 0.0668, 0.0622, 0.0540, 0.0704, 0.0405, 0.0919, and 0.0386 for 1, 2, 3, 5a, 5b, 6, and 7, respectively.
P
2
1=2
Goodness-of-fit ¼ ½ ½wðF 2o ꢀ F c2Þ =ðNrflns ꢀ NparamsÞꢁ
.

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J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
O
O
THF
CH3
r.t., 12 h
Al
15 ml THF
OH
+ AlMe3
O
O
H3C
Al
O
OH
r.t., 12 h
1 or 2
15 ml Toluene
Al
CH3
O
Scheme 3.
HO
OH
Co2(CO)8
+
C
C C
C
Ph
Ph
Ph
Ph
H
H
O
C
O
C
H
C
H
Ph
Ph
Ph
Ph
O
C
O
C
C
C
Ph
Ph
Ph
Ph
PPh CH PPh
+
C
2
2
2
(OC)2Co
Ph2P
Co(CO)2
PPh2
(OC)3Co
Co(CO)3
C
3
4
H2
Scheme 4.
Fig. 1. ORTEP drawing of 1. Hydrogen atoms are omitted for clarity.
˚
Selected bond lengths (A) and bond angles (°): Co(1)–C(2) 1.965(4);
Co(1)–C(1) 1.965(4); Co(1)–Co(2) 2.4720(8); Co(2)–C(1) 1.968(4); Co(2)–
C(2) 1.969(4); O(1)–C(7) 1.444(4); O(2)–C(3) 1.438(5); C(1)–C(2) 1.341(5);
C(1)–C(7) 1.497(5); C(2)–C(3) 1.508(5); C(3)–C(5) 1.531(6); C(3)–C(4)
1.538(6); C(7)–C(8) 1.532(6); C(7)–C(9) 1.538(6); C(2)–Co(1)–C(1)
39.89(15); C(1)–Co(2)–C(2) 39.81(15); C(2)–C(1)–C(7) 139.6(3); Co(1)–
C(1)–Co(2) 77.87(14); Co(1)–C(2)–Co(2) 77.87(14); C(1)–C(2)–C(3)
138.6(4); O(2)–C(3)–C(2) 106.5(3); O(1)–C(7)–C(1) 105.7(3); C(1)–C(7)–
C(8) 112.7(3); C(1)–C(7)–C(9) 110.0(3).
Fig. 3. ORTEP drawing of 3. Hydrogen atoms are omitted for clarity.
˚
Selected bond lengths (A) and bond angles (°): Co(1)–C(1) 1.972(3);
Co(1)–C(2) 1.978(3); Co(1)–Co(2) 2.4472(6); Co(2)–C(1) 1.952(3); Co(2)–
C(2) 1.985(3); O(1)–C(3) 1.445(4); O(2)–C(4) 1.435(3); C(1)–C(2) 1.346(4);
C(1)–C(3) 1.521(4); C(2)–C(4) 1.536(4); C(1)–Co(1)–C(2) 39.84(11); C(1)–
Co(2)–C(2) 39.98(11); Co(2)–C(1)–Co(1) 77.15(10); Co(1)–C(2)–Co(2)
76.28(10); C(2)–C(1)–C(3) 140.4(3); C(1)–C(2)–C(4) 138.2(3); O(1)–C(3)–
C(1) 102.8(2); O(2)–C(4)–C(2) 106.9(2).
molecules do occur and the self-aggregation process always
lead to a great amount of precipitation. The sequence of
reactions shown in Scheme 1 is reversed in the synthesis
of 4. Firstly, the alkynyl alcohol is allowed to bridge to
the dicobalt fragment. As predicted by the Dewar–
Chatt–Duncanson’s model, bulky substituents of the
alkyne bend away from the dicobalt center. Then, the
dppm is added to the alkyne bridged dicobalt fragment.
The dppm-alkynyl alcohol sequence will not lead to 4
Fig. 2. ORTEP drawing of 2. Hydrogen atoms are omitted for clarity.
˚
Selected bond lengths (A) and bond angles (°): Co(1)–Co(2) 2.4639(5);
C(1)–C(2) 1.324(3); Co(1)–C(1) 1.965(2); Co(1)–C(2) 1.971(2); Co(2)–C(2)
1.951(3); Co(2)–C(1) 1.972(2); C(1)–C(3) 1.522(4); C(2)–C(8) 1.526(4);
O(1)–C(3) 1.445(3); O(2)–C(8) 1.434(3); C(2)–C(1)–C(3) 137.5(2); C(1)–
C(2)–C(8) 136.9(2); O(1)–C(3)–C(1) 106.4(2); O(2)–C(8)–C(2) 103.4(2);
C(1)–Co(1)–C(2) 39.30(10); C(2)–Co(2)–C(1) 39.44(10); Co(1)–C(1)–Co(2)
77.49(9); Co(2)–C(2)–Co(1) 77.86(9).

J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
2991
due to the bulkiness of the latter. Compounds 3 and 4 were
2.2. Preparation of cobalt-containing alcohols
characterized by spectroscopic means. In addition, the
molecular structure of 3 was determined by a single-crystal
X-ray diffraction method. As revealed from the crystal
structure, there is an intramolecular hydrogen-bonding
between the oxygen atom of one and the hydrogen atom
Several cobalt-containing alcohols were prepared using
a procedure similar to the one for synthesis of diols. The
reaction of Co2(CO)8 with HCC„CCPh2OH in toluene
at 60 °C for 2 h furnished [Co2(CO)6(l-g-HC„CCPh2OH]
(5a). Further reaction of 5a with PPh2NHPPh2 in toluene
at 80 °C for 16 h produced [(l-PPh2NHPPh2)Co2(CO)4-
(l-g-HC„CCPh2OH)] (5b) (Scheme 5). The alkynyl
alcohol was first allowed to bridge to the dicobalt frag-
ment. Then, PPh2NHPPh2 was added to alkyne-bridged
dicobalt fragment. Again, reversing the sequence did not
lead to the formation of 5b. Here PPh2NHPPh2 was chosen
. . .
˚
of another hydroxyl group. The H O distance is 1.934 A
for 3. Two hydroxyl protons of 3 and 4 are equivalent
resulting in broad signals at 4.31 ppm and 2.51 ppm,
1
respectively, in their H NMR spectra in CDCl3. A triplet
signal at 3.69 ppm (JP-H = 10.5 Hz) observed in the 1H
NMR spectra of 4 is assigned to the methylene protons
(Figs. 3 and 4).
Fig. 5. ORTEP drawing of 5b. Hydrogen atoms are omitted for clarity.
˚
Selected bond lengths (A) and bond angles (°): Co(1)–Co(2) 2.4467(6);
Fig. 4. ORTEP drawing of 5a. Hydrogen atoms are omitted for clarity.
Selected bond lengths (A) and bond angles (°): Co(1)–C(2) 1.969(4);
Co(1)–C(1) 1.986(4); Co(1)–Co(2) 2.4729(8); Co(2)–C(2) 1.951(4); Co(2)–
C(1) 1.977(4); O(1)–C(3) 1.436(4); C(1)–C(2) 1.340(5); C(1)–C(3) 1.499(5);
C(2)–Co(1)–C(1) 39.60(15); C(2)–Co(2)–C(1) 39.88(15); C(2)–C(1)–C(3)
146.5(4); Co(2)–C(2)–Co(1) 78.21(15); Co(2)–C(1)–Co(1) 77.22(13); O(1)–
C(3)–C(1) 109.3(3).
Co(1)–C(2) 1.932(3); Co(1)–C(1) 1.973(3); Co(1)–P(1) 2.2028(10); Co(2)–
C(2) 1.956(3); Co(2)–C(1) 1.957(3); Co(2)–P(2) 2.1997(10); P(1)–N
1.687(3); P(2)–N 1.679(3); O(1)–C(3) 1.451(4); C(1)–C(2) 1.339(4); C(1)–
C(3) 1.523(4); C(2)–Co(1)–C(1) 40.09(13); C(2)–Co(2)–C(1) 40.01(13); N–
P(1)–Co(1) 111.64(10); N–P(2)–Co(2) 112.53(10); P(2)–N–P(1) 122.53(16);
C(2)–C(1)–C(3) 141.8(3); Co(2)–C(1)–Co(1) 77.01(12); Co(1)–C(2)–Co(2)
77.99(13); O(1)–C(3)–C(1) 107.4(3).
˚
+ PPh2NHPPh2
Co2(CO)8
+ H C C R
H
R
C
C
H
R
C
C
(OC)2Co
Ph2P
Co(CO)2
PPh2
+
(OC)3Co
Co(CO)3
R=CPh2OH
N
H
5a
Scheme 5.
5b

2992
J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
Fig. 6. ORTEP drawing of 6. Hydrogen atoms are omitted for clarity.
Selected bond lengths (A) and bond angles (°): Co(1)–Co(2) 2.4675(7);
Fig. 7. ORTEP drawing of 7. Hydrogen atoms are omitted for clarity.
Selected bond lengths (A) and bond angles (°): Co(1)–Co(2) 2.4701(10);
˚
˚
Co(1)–C(2) 1.950(4); Co(1)–C(1) 1.960(4); Co(1)–P(1) 2.2018(9); Co(2)–
C(2) 1.957(4); Co(2)–C(1) 1.966(4); Co(2)–P(2) 2.2045(9); P(1)–N 1.683(3);
P(2)–N 1.687(3); O(1)–C(3) 1.411(5); C(1)–C(2) 1.341(5); C(2)–C(3)
1.489(4); C(2)–Co(1)–C(1) 40.10(14); C(2)–Co(2)–C(1) 39.96(14);
N–P(1)–Co(1) 111.46(10); N–P(2)–Co(2) 111.76(10); P(1)–N–P(2)
123.19(17); Co(1)–C(1)–Co(2) 77.86(13); C(1)–C(2)–C(3) 141.8(4);
Co(1)–C(2)–Co(2) 78.32(13); O(1)–C(3)–C(2) 110.0(3).
Co(1)–C(1) 1.925(6); Co(1)–C(2) 1.965(6); Co(1)–P(1) 2.2017(15); Co(2)–
C(2) 1.944(6); Co(2)–C(1) 1.947(6); Co(2)–P(2) 2.2023(16); O(1)–C(4)
1.445(5); P(1)–N 1.669(4); P(2)–N 1.687(4); C(1)–C(2) 1.313(7);
C(2)–C(3) 1.505(7); C(3)–C(4) 1.458(7); C(2)–Co(2)–C(1) 39.5(2); C(1)–
Co(1)–C(2) 39.4(2); N–P(1)–Co(1) 112.24(15); N–P(2)–Co(2) 110.88(15);
P(1)–N–P(2) 123.3(2); Co(1)–C(1)–Co(2) 79.3(2); C(1)–C(2)–C(3)
140.1(6); Co(2)–C(2)–Co(1) 78.4(2); C(4)–C(3)–C(2) 113.1(5); O(1)–C(4)–
C(3) 111.4(5).
H
R
C
C
H C
C R
+
Co2(CO)8
(OC)2Co
Ph2P
Co(CO)2
PPh2
OH) in 12 h (Scheme 6). Compounds 6 and 7 were charac-
terized by spectroscopic means. Their molecular structures
were determined by the single-crystal X-ray diffraction
method. To the best of our knowledge, compounds 5b, 6
and 7 are the first reported examples of PPh2NHPPh2-
bridged dicobalt complexes. The crystal structures of 6
and 7 show that the –OH and –NH groups point at differ-
ent directions as those in 5b does (see Fig. 7).
+
PPh2NHPPh2
6: R=CH2OH
7: R=C2H4OH
N
H
Scheme 6.
as a bridging ligand to stabilize the dicobalt complex as the
dppm did in the case of compound 4. This choice is due to
the PPh2NHPPh2 ability to function as an amine-like
ligand, which dppm does not have. In addition to the
characterization by spectroscopic means the molecular
structures of 5a and 5b were determined by the single-
crystal X-ray diffraction method. The structure of 5b
revealed that the –OH and -NH groups point at different
directions. In CDCl3, a hydroxyl proton is observed at
2.60 and 3.00 ppm for 5a and 5b, respectively, in 1H
NMR. A broad signal at 3.62 ppm and a triplet signal at
5.75 ppm (JPH = 9.0 Hz) are assigned to the acetylenic
proton and NH proton, respectively, of 5b (see Figs. 5
and 6).
1
Signals observed at 1.69 and 2.01 ppm in the H NMR
spectra of 6 and 7, respectively, in CDCl3 are assigned to
the corresponding hydroxyl protons. Broad signals appear-
ing at 3.60 ppm for 6 and 3.52 ppm for 7 are assigned to
terminal acetylene protons. The triplet signals at
5.34 ppm for 6 and 5.30 ppm for 7 are assigned to the
NH protons of the bridging PPh2NHPPh2.
2.3. Structural comparison of cobalt-containing diols and
alcohols
Selected structural parameters of 1, 2, 3, 5a, 5b, 6, and 7
are given in Table 2 for the purpose of comparison. The
atom numbering scheme of the framework of all these com-
pounds is the same. As shown in Table 2, these frameworks
are not very different. Again, it shows that the alkyne-
bridging dicobalt framework (Co2C2) is a rigid structure
(Diagram 1).
The reaction of Co2(CO)8 with PPh2NHPPh2 in toluene
at 65 °C produced [Co2(CO)6(l-g-PPh2NHPPh2] in 12 h.
Further reaction of the latter compound with HC„CR
(R = CH2OH or C2H4OH) in toluene at 65 °C furnished
[Co2(CO)6(l-g-HC„CR] (6: R = CH2OH; 7: R=C2H4-

J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
2993
Table 2
Comparison of selected structural parameters of 1, 2, 3, 5a, 5b, 6, and 7
1
2
3
5a
5b
6
7
˚
Bond length (A)
Co(1)–Co(2)
C(1)–C(2)
C(1)–Co(1)
C(1)–Co(2)
C(2)–Co(1)
C(2)–Co(2)
C(1)–C(A)
C(2)–C(B)
C(A)–O(1)
C(B)–O(2)
Co(1)–P(1)
Co(2)–P(2)
P(1)–X
2.4720(8)
1.341(5)
1.965(4)
1.968(4)
1.965(4)
1.969(4)
1.497(5)
1.508(5)
1.444(5)
1.438(5)
2.4639(5)
1.324(3)
1.965(2)
1.972(2)
1.971(2)
1.951(3)
1.522(4)
1.526(4)
1.445(3)
1.434(3)
2.4472(6)
1.346(4)
1.972(3)
1.952(3)
1.978(3)
1.985(3)
1.521(4)
1.536(4)
1.445(4)
1.435(3)
2.4729(8)
1.340(5)
1.986(4)
1.977(4)
1.969(4)
1.951(4)
1.499(5)
2.4467(6)
1.339(4)
1.973(3)
1.957(3)
1.932(3)
1.956(3)
1.523(4)
2.4675(7)
1.341(5)
1.960(4)
1.966(4)
1.950(4)
1.957(4)
2.4701(10)
1.313(7)
1.925(6)
1.947(6)
1.965(6)
1.944(6)
1.489(4)
1.411(5)
1.436(4)
1.451(4)
2.2028(10)
2.1997(10)
1.687(3)
2.2018(9)
2.2045(9)
1.683(3)
1.687(3)
2.2017(15)
2.2023(16)
1.669(4)
P(2)–X
1.679(3)
1.687(4)
˚
Distance (A)
O(2)–H(1)
O(1)–O(2)
2.052
2.847
3.303
2.637
1.934
2.709
Angle (°)
C(A)–C(1)–C(2)
C(B)–C(2)–C(1)
Co(1)–C(1)–Co(2)
Co(1)–C(2)–Co(2)
C(1)–Co(1)–C(2)
C(1)–Co(2)–C(2)
P(1)–X–P(2)
Co(1)–P(1)–X
Co(2)–P(2)–X
C(1)–C(A)–O(1)
C(2)–C(B)–O(2)
139.6(3)
138.6(4)
77.87(14)
77.87(14)
39.89(15)
39.81(15)
137.5(2)
136.9(2)
77.49(9)
77.86(9)
39.30(10)
39.44(10)
140.4(3)
138.2(3)
77.15(10)
76.28(10)
39.84(11)
39.98(11)
146.5(4)
141.8(3)
140.1(6)
141.8(4)
77.22(13)
78.21(15)
39.60(15)
39.88(15)
77.01(12)
77.99(13)
40.09(13)
40.01(13)
122.53(16)
111.64(10)
112.53(10)
107.4(3)
77.86(13)
78.32(13)
40.10(14)
39.96(14)
123.19(17)
111.46(10)
111.76(10)
79.3(2)
78.4(2)
39.4(2)
39.5(2)
123.3(2)
112.24(15)
110.88(15)
105.7(3)
106.5(3)
106.4(2)
103.4(2)
102.8(2)
106.9(2)
109.3(3)
110.0(3)
(2)
terated solvents were purified before use. Most of separa-
tions were performed by Centrifugal Thin Layer
Chromatography (CTLC, Chromatotron, Harrison model
(1)
H
(2)
H
O(1)
(A)CR1R2
O
R2R1C (B)
(2)
(1)
1
8924). The H and 31P NMR spectra were recorded on a
C
C
Varian-400 spectrometer at 400.44 and 162.10 MHz,
respectively; 13C NMR spectra were recorded on a Varian
VXR-300 S spectrometer at 75.43 MHz. Chemical shifts
are reported in ppm relative to the residual proton signals
of deuterated CHCl3 or CH2Cl2. Mass spectra were
recorded on a JOEL JMS-SX/SX 102A GC/MS/MS spec-
trometer. Elemental analyses were obtained on a Heraeus
CHN-O-S-Rapid instrument.
(OC)2Co
Co(CO)2
(1)
(2)
PPh2
Ph2P
(1)
(2)
X: CH2 or NH
X
Diagram 1. A generalized structure for 1, 2, 3, 5a, 5b, 6, and 7.
2.4. Summary
3.1. Synthesis of 1 and 2
Several cobalt-containing alcohols and diols were pre-
pared and characterized by NMR spectroscopic and sin-
gle-crystal X-ray diffraction. Their molecular structures
were compared. Unfortunately, reactions of the metal-con-
taining diol ligands with aluminum complexes such as
AlEt3 or AlMe3 resulted in a number of unidentified
products.
Co2(CO)8 (0.342 g, 1.000 mmol), 3,6-dimethyl-4-octyn-
3,6-diol (0.170 g, 1.000 mmol) and 10 mL of THF were
placed in a 100 mL round-bottomed flask charged with a
magnetic stirrer. The solution was stirred at 25 °C for
4 h. Then the solvent was removed under reduced pressure,
and the resulted dark-red residue was separated by CTLC.
A red band was eluted out using a mixed solvent system
(CH2Cl2/EA = 1:1). The product was identified as 1
(0.437 g, 0.96 mmol, 96%). A similar procedure was used
for the preparation of 2. Co2(CO)8 (0.342 g, 1.000 mmol),
4,7-dimethyl-5-decyn-4,7-diol (0.198 g, 1.000 mmol) and
3. Experimental
General information: All manipulations were carried out
under a dry nitrogen atmosphere. Solvents including deu-

2994
J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
10 mL of THF were placed in 100 mL round-bottomed
flask charged with a magnetic stirrer. The solution was
stirred at 25 °C for 4 h followed by workup. A dark-red
band was eluted out using a mixed solvent system
(EA:CH2Cl2 = 1:1). The product was identified as 2
(0.460 g, 0.95 mmol, 95%).
arene), 146.72(s, ipso of arene), 204.68(br., COs); 31P
NMR (CDCl3, d/ppm): 35.8(s, dppm); Anal. Calc. for 4:
C, 68.14; H, 4.14. Found: C, 64.64; H, 4.55%; IR(KBr/
cmꢀ1): 1966.5(s), 1992.7(s), 2022.8(s); MS (m/z):
977(M+ꢀCO). color: brown (solid state).
1: 1H NMR (CDCl3, d/ppm): 1.09(br., 6H, C–CH2–
CH3), 1.54(br., 6H, C–CH3), 1.83(br., 4H, C–CH2),
2.99(br., 2H, OH); 13C NMR (CDCl3, d/ppm): 8.76(s, C–
CH2–CH3), 28.79(s, C–CH2), 37.90(s, C–CH3), 75.15(s,
C„C), 106.89(s, C–OH), 199.83(s, CO); Anal. Calc. for
1: C, 42.13; H, 3.98. Found: C: 41.17, H: 3.84%. IR(KBr/
cmꢀ1): 2017.7(s), 2052.5(s), 2093.0(s), 3332.0(br.); color:
red (solid state).
3.4. Synthesis of 5a and 5b
Co2(CO)8 (0.171 g, 0.500 mmol), 1,1-diphenyl-2-pro-
pyn-1-ol (0.104 g, 0.500 mmol) and 5 ml of toluene were
placed in a 100 mL round-bottomed flask charged with a
magnetic stirrer. The red colored solution was stirred at
60 °C for 2 h. To the mixture was then added N,N-
bis(diphenylphosphino)amine (0.192 g, 0.500 mmol) with
5 cm3 of toluene followed by stirring at 80 °C for additional
16 h. The solvent was removed under reduced pressure, and
the resulting residue was chromatography by CTLC. Com-
plex 5a was obtained from the first red band eluted by
hexane, while complex 5b from the second red-pink band
by CH2Cl2/hexane (1/1) solution. The yields for 5a and
5b were 33.9% (0.084 g, 0.170 mmol) and 39.1% (0.161 g,
0.196 mmol), respectively.
2: 1H NMR (CDCl3, d/ppm): 0.99(br., 6H, C–CH2–
CH3), 1.56(br., 10 H, C–CH2, C–CH3), 1.77(br., 4H, C–
CH2), 2.98(br., 2H, OH); 13C NMR (CDCl3, d/ppm):
14.40(s, C–CH2–CH2-CH3), 17.70(s, C–CH2–CH3), 29.48,
29.66(d, C–CH2), 47.77(s, C–CH3), 75.13(s, C„C),
106.96(s, C–OH), 199.8(s, CO); Anal. Calc. for 2: C,
44.65; H, 4.58. Found: C: 44.48, H: 4.70%; IR(KBr/
cmꢀ1): 2022.6(s), 2053.5(s), 2091.7(s), 3257.9(br.); color:
red (solid state).
1
5a: H NMR (CDCl3, d/ppm): 2.60(s, 1H, OH), 6.52(s,
1H, CH), 7.23–7.25(br., 2H, arene), 7.30–7.32(br., 4H,
arene), 7.69–7.71(br., 4H, arene); 13C NMR (CDCl3, d/
ppm): 73.06, 80.08(s, C„C), 105.80(s, C–(OH)Ph2),
125.71(s, arene), 127.48(s, arene), 128.26(s, Ph), 146.71(s,
ipso of arene), 198.88(br., COs); Anal. Calc. for 5a: C,
51.04; H, 2.45. Found: C, 50.07; H, 2.99%; IR(KBr/
cmꢀ1): 1977.7(w), 2002.7(s), 2027.8(s), 2051.8(s),
2093.9(m); MS (m/z): 466 (M+ꢀCO); color: red (solid
state).
3.2. Synthesis of 3
A 100 cm3 flask was charged with dicobalt octacarbonyl,
Co2(CO)8 (0.171 g, 0.500 mmol) and 1,1,4,4-tetraphenyl-2-
butyn-1,4-diol (0.195 g, 0.500 mmol) in 5 ml of THF. The
mixture was stirred at 60 °C for 3 h resulting in a red
solution. The solvent was removed under reduced pressure,
and the resulting residue was chromatography by CTLC. A
red band was eluted out using a mixed solvent system
(CH2Cl2/hexane = 1:1). The product was identified as 3
(0.316 g, 0.467 mmol, 93.4%).
5b: 1H NMR (CDCl3, d/ppm): 3.00(s, 1H, OH), 3.61(br.
2 H, CH2 or NH), 5.75(t, JPH = 9.0 Hz, 1H, CH), 7.15–
7.78(br., 30 H, arene); 13C NMR (CDCl3, d/ppm):
73.12(s, C„CH), 80.61(s, C„C(OH)Ph2), 126.31–
130.90(br., arene), 147.92(s, ipso of arene), 201.20(br.,
COs), 206.24(br., COs); 31P NMR(CDCl3, d/ppm): 98.6(s,
2 P, dppm); Anal. Calc. for 5b: N, 1.70; C, 62.71; H,
4.04. Found: N, 2.89; C, 61.85; H, 4.21%; IR(KBr/cmꢀ1):
1977.0(s), 2003.0(s), 2027.7(s); MS (m/z): 823 (M+); color:
red (solid state).
3: 1H NMR (CDCl3, d/ppm): 4.31(s, 2H, OH), 7.28
(br., 12H, Ph), 7.61(br., 8H, Ph); 13C NMR (CDCl3, d/
ppm): 80.62(s, C„C), 108.23(s, C–(OH)Ph2), 126.93(s,
arene), 127.67(s, arene), 128.03(s, Ph), 146.12(s, ipso of
arene), 198.46(br., COs); Anal. Calc. for 3: C, 60.37, H,
3.28. Found: C, 59.60; H, 3.62%; color: red (solid state).
3.3. Synthesis of 4
3.5. Synthesis of 6 and 7
A 100 cm3 flask was charged with complex 3 (0.344 g,
0.509 mmol) and dppm (0.196 g, 0.509 mmol) in 5 ml of
toluene. The mixture was stirred at 100 °C for 16 h yielding
a dark-brown solution. The solvent was removed under
reduced pressure, and the resulting residue was chromato-
graphy by CTLC. The first band was eluted out using a
mixed solvent system (CH2Cl2/hexane = 2:1). The product
A 100 cm3 round flask was charged with Co2(CO)8
(0.342 g, 1.000 mmol) and N,N-bis(diphenylphosph-
ino)amine (0.385 g, 1.000 mmol) with 15 cm3 of THF.
The mixture was warmed up to 65 °C and stirred for
12 h. Then, one molar equivalent of 2-propyn-1-ol
(0.056 g, 1.000 mmol) was added. The mixture was stirred
at 65 °C for another 12 h. The resulting green solution
was purified by centrifugal thin-layer chromatography
(CTLC). The second red-colored band was eluted out with
CH2Cl2. The solvent was removed in vacuo, and the result-
ing solid was identified as 6 (0.618 g, 0.920 mmol, 92%
yield). A similar procedure was used for the preparation
was identified as the title compound
4
(0.501 g,
0.499 mmol, 97.9%).
1
4: H NMR (CDCl3, d/ppm): 2.51(s, 2H, OH), 3.69(t,
JPH = 10.5 Hz, 2H, CH2), 7.15–7.46(br. 40 H, arene); 13C
NMR (CDCl3, d/ppm): 36.28(t, JPC = 82.5 Hz, CH2),
81.09(s, C„C), 109.81(s, C–(OH)Ph2), 126.95–131.52(br.,

J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
2995
of 7. Co2(CO)8 (0.342 g, 1.000 mmol), N,N-bis(diph-
Acknowledgement
enylphosphino)amine (0.385 g, 1.000 mmol) and 15 mL of
THF were placed in a 100 mL round-bottomed flask equi-
ped with a magnetic stirrer. The solution was stirred at
65 °C for 12 h. Then, one molar equivalent of 3-butyn-1-
ol (0.070 g, 1.000 mmol) was added. The solution was stir-
red at 65 °C for another 12 h. The resulting green solution
was purified by centrifugal thin-layer chromatography
(CTLC). The second red-colored band was eluted out with
CH2Cl2. The solvent was removed in vacuo, and the resid-
ual solid was identified as 7 (0.589 g, 0.86 mmol, 86%
yield).
We thank the National Science Council of the R.O.C.
(Grant NSC-94-2113-M-005-011) for the financial support.
Appendix A. Supplementary material
CCDC 616907, 616908, 616909, 616910, 616911, 616912
and 616913 contain the supplementary crystallographic
data for compounds 1, 2, 3, 5a, 5b, 6, and 7. These data
can be obtained free of charge via http://www.ccdc.cam.ac.
uk/conts/retrieving.html, or from the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.poly.2007.01.037.
6: 1H NMR (CDCl3, d/ppm): 1.69(s, 1H, OH), 3.60(s, 1
H, NH), 4.76(d, JHꢀH = 6.0 Hz, 2H, CH2), 5.34(t, 1H,
„CH), 7.38–7.46(br., 10H, arene); 13C NMR (CDCl3, d/
ppm): 65.10(s, CH2–OH), 71.10(s, C–CH2–OH), 101.84(s,
„CH), 128.47–130.41(arene), 140.10(d, Jp-c = 36.6 Hz,
ipso-arene), 202.6 (br, COs), 206.3 (br, COs); 31P NMR
(CDCl3, d/ppm): 33.7(s, PNP); Anal. Calc. for 6: C,
55.46, H, 3.75, N, 2.09%. Found: C, 54.54, H, 3.90, N,
2.71%; M.S.(FAB): 643(M+ꢀCO); color: red (solid state).
References
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1
7: H NMR (CDCl3, d/ppm): 2.01(s, 1H, OH), 3.12(d,
JHꢀH = 6.0 Hz, 2H, CH2–OH), 3.52(s, 1H, NH), 3.98(d,
JHꢀH = 6.0 Hz, 2H, CH2–CH2), 5.30(t, 1 H, „CH),
7.37–7.44(br., 10H, arene); 13C NMR (CDCl3, d/ppm):
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are summarized in Table 1.
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1
The hydrogen atoms were ride on carbons or oxygens in their idealized
˚
positions and held fixed with the C–H distances of 0.96 A.

2996
J.-C. Lee et al. / Polyhedron 26 (2007) 2987–2996
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˚
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