Observations on reaction pathways of dicobalt octacarbonyl with alkynyl amines

Article abstract of DOI:10.1016/j.jorganchem.2004.07.047

Treatments of a bis(diphenylphosphino)methylene (dppm) bridged dicobalt complex, Co₂(CO)₆(dppm) (4), with propargylamine and 4-ethynylaniline at 25 °C for 24 h gave [(dppm)Co₂ (CO)₄(μ-HC≡CCH₂NH₂)] (5) and [(dppm)Co₂(CO)₄(μ-HC≡CC₆ H₄NH₂)] (6), respectively. Interestingly, only alkynyl amines bridged dicobalt complexes were obtained rather than the previously observed coupling products. The results are in acceptance with the proposed mechanism which describes the formation of the coupling products {[Co₂(CO)₆(μ-HC≡C-)] -CH₂NH}₂C=O (1) and {[Co₂(CO) ₆(7μ-HC≡C-)]-C₆H₄N}₂ (2) from the reaction of Co₂(CO)₈ with propargylamine and 4-ethynylaniline, respectively. Similar results were attained for the reactions of 4 with propioamide and 1-ethynylcyclohexylamine at 25 °C for 24 h which yielded [(dppm) Co₂(CO)₄(μ-HC≡CC(=O)NH₂)] (7) and [(dppm)Co₂(CO)₄(μ-HC≡CC₆ H₁₀NH₂)] (8), respectively. Reaction of 1-ethynylcyclohexylamine with one molar equivalent of Co₂(CO)₈ in THF at 25 °C for 15 min gave an alkyne bridged dicobalt complex, [Co₂(CO)₆ (μ-HC≡ CC₆H₁₀NH₂)] (9). Direct treatment of 3-ethynlaniline with one molar equivalent of Co₂(CO)₈ in THF at 25 °C for 1 h gave an alkyne bridged dicobalt complex, [Co₂(CO)₆ (μ-HC≡CC₆ H₄NH₂)] (11) and an azobenzene derivative, {[Co₂(CO)₆ (μ-HC≡C)]C₆H₄N}₂ (10). Further treatments of 8, 9, and 11 with one molar equivalent of Sanger's reagent, 2,4-dinitrofluorobenzene, in THF at25 °C for 48 h gave [(dppm)Co₂(CO)₄ (μ-HC≡CC₆H₁₀NHC₆H₃ (NO₂)₂)] (13), [Co₂(CO)₆ (μ-HC≡CC₆H₁₀NHC₆H₃ (NO₂)₂)] (14), and [Co₂(CO)₆ (μ-HC≡CC₆H₄NHC₆H₃ (NO₂)₂)] (15), respectively.

Full text of DOI:10.1016/j.jorganchem.2004.07.047

Journal of Organometallic Chemistry 689 (2004) 3449–3460
www.elsevier.com/locate/jorganchem
Observations on reaction pathways of dicobalt
octacarbonyl with alkynyl amines
*
Fung-E Hong , Yi-Luen Huang, Hsueh-Liang Chen
Department of Chemistry, National Chung-Hsing University, Taichung 40227, Taiwan
Received 29 May 2004; accepted 27 July 2004
Available online 11 September 2004
Abstract
Treatments of a bis(diphenylphosphino)methylene (dppm) bridged dicobalt complex, Co2(CO)6(dppm) (4), with propargylamine
and 4-ethynylaniline at 25 °C for 24 h gave [(dppm)Co2(CO)4(l-HC„CCH2NH2)] (5) and [(dppm)Co2(CO)4(l-HC„CC6H4NH2)]
(6), respectively. Interestingly, only alkynyl amines bridged dicobalt complexes were obtained rather than the previously observed
coupling products. The results are in acceptance with the proposed mechanism which describes the formation of the coupling prod-
ucts {[Co2(CO)6(l-HC„C–)]–CH2NH}2C‚O (1) and {[Co2(CO)6(l-HC„C–)]–C6H4N‚}2 (2) from the reaction of Co2(CO)8
with propargylamine and 4-ethynylaniline, respectively. Similar results were attained for the reactions of 4 with propioamide and
1-ethynylcyclohexylamine at 25 °C for 24 h which yielded [(dppm)Co2(CO)4(l-HC„CC(‚O)NH2)] (7) and [(dppm)Co2(CO)4(l-
HC„CC6H10NH2)] (8), respectively.
Reaction of 1-ethynylcyclohexylamine with one molar equivalent of Co2(CO)8 in THF at 25 °C for 15 min gave an alkyne
bridged dicobalt complex, [Co2(CO)6(l-HC„CC6H10NH2)] (9). Direct treatment of 3-ethynlaniline with one molar equivalent of
Co2(CO)8 in THF at 25 °C for 1 h gave an alkyne bridged dicobalt complex, [Co2(CO)6(l-HC„CC6H4NH2)] (11) and an azoben-
zene derivative, {[Co2(CO)6(l-HC„C)]C6H4N‚}2 (10).
Further treatments of 8, 9, and 11 with one molar equivalent of SangerÕs reagent, 2,4-dinitrofluorobenzene, in THF at 25 °C for 48 h
gave [(dppm)Co2(CO)4(l-HC„CC6H10NHC6H3(NO2)2)] (13), [Co2(CO)6(l-HC„CC6H10NHC6H3(NO2)2)] (14), and [Co2(CO)6(l-
HC„CC6H4NHC6H3(NO2)2)] (15), respectively.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Cobalt-mediated catalytic reaction; Carbonylation; Azobenzene; SangerÕs reagent
1. Introduction
Generally, these type of complexes are prepared
straightforward from the thermal reaction of Co2(CO)8
with designated alkynes [3]. The alkyne uses the both
sets of filled p orbitals to bond with the dicobalt frag-
ment. According to the Dewar–Chatt–DuncansonÕs
model, the substituents on the bridged alkyne shall bend
away from the metal center due to the metal to ligand
p-electron backbonding mechanism [4].
Although catalytic carbonylation has been explored
for many years, the subject remains of much interest
to many researchers [5]. Normally, harsh reaction condi-
tions including elevated temperature and high pressures
are required for employing transition metals such as Mn
Reactions of alkynes with various metal complexes
were extensively studied because of their diverse bond-
ing modes and wide-ranged reactivities are interested
to many chemists [1] In particular, the structures and
reactivities of the alkyne bridged dicobalt complexes,
Co2(CO)6(l-alkyne), were well examined mainly due to
key roles played in the Pauson–Khand reactions [2].
*
Corresponding author. Tel.: +88 642 286 2547; fax: +88 642 286
2547.
E-mail address: fehong@dragon.nchu.edu.tw (Fung-E Hong).
0022-328X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.07.047

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Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
[6], Co [7], Ni [8], Ru [9], Rh [10], W [11], Pd [12] as cat-
alyst. As for main group elements such as S [13] or Se
[14], large quantities of metals are generally required be-
sides the severe reaction conditions. Our previous results
had demonstrated that an unusual carbonylation of pri-
mary amine took place at room temperature utilizing
Co2(CO)8 as catalyst (Scheme 1). Compound 1, {[Co2
(CO)6(l-HC„C–)]–CH2NH}2C‚O, can be viewed as
two deprotonated propargylamine bridged dicobalt
fragments, [Co2(CO)6(l-C„CCH2NH)]ꢀ, being cou-
pled by a carbonyl group through carbonylation [15].
We also reported a one-pot reaction of the formation
for an azobenzene compound, {[Co2(CO)6(l-HC„C–)]
–C6H4N‚}2 (2), a potential liquid crystal precursor
[16], from 4-ethynylaniline through cobalt-assisted cou-
pling reaction (Scheme 1) [17]. Interestingly, two diver-
gent types of products, urea- and azobenzene-like
derivatives, were observed from reactions started with
close-related alkynyl amines.
A reaction mechanism was proposed to account for
the formation of 1 and 2 is presented in Figs. 1 and 2.
It is apparent that the alkynyl amine plays dual roles
here: first, as a metal-bridging moiety; second, as a coor-
dinating ligand towards the dicobalt complex. It is gen-
erally accepted that in the first reaction step, the dicobalt
hexacarbonyl fragment is bridged by the triple bond of
the alkynyl amine and leads to the formation of
NH2[X] ([X]: Co2(CO)6(l-HC„C-Y-), 3a: Y = C6H4;
3b: Y = CH2). Thereafter, the acidity of the amine pro-
tons of 3 is enhanced. It is followed by the coordination
of 3 through its amine site to another molar equivalent
of Co2(CO)8. After that, an oxidative addition of
NH2[X] towards Co2(CO)8 takes place and then it leads
to the cleavage of the cobalt–cobalt bond. Presumably,
an activated complex [(CO)4Co–NH[X]] (I), having a di-
rect Co–N covalent bond as well as a side product
HCo(CO)4, was formed [18]. The latter might be acting
as a strong inorganic acid or convert disproportionately
to Co2(CO)8 and H2. Starting from (I), there are two dis-
tinct routes, Route A and B, each leads to the formation
of 1- or 2-like products. For the Route A, there are two
most probable reaction courses i.e. Course 1 and
Course 2 are proposed and examined theoretically [19].
Elementary steps from (II) to (X) for both reaction path-
ways, including the amino group migration to the
Co–CO bond, additional NH2CH3 molecule associa-
tion, hydride migration of the coordinated amine proton
to the cobalt center, and reductive elimination of –
C(‚O)NHCH3 with –NH2CH3, are modeled and
inspected. By contrast, for the Route B, the first step in-
volves the release of a CO from (I), forming an activated
complex (XI), which subsequently dimmerized to yield
(XII). Then, consecutive processes including hydride
migration, hydrogen elimination, and formation of
N‚N bond are attributed to the formation of interme-
diates (XIII), (XIV) and (XV), respectively. The proc-
esses are ended with the elimination of 2 from (XV). It
is proposed that the formation of either 1- or 2-type
compound depends on the characteristic of the activated
complex [(CO)4Co–NH[X]] (I).
This work describes our efforts in comprehending the
diversities of the catalytic reactions of dicobalt carbonyl
complexes with some designated alkynyl amines by
experimental means. The processes of labeling terminal
amino group of the alkyne bridged dicobalt complexes
by the SangerÕs reagent are also reported.
2. Results and discussion
2.1. Reactions of Co2(CO)6(dppm) (4) with alkynyl
amines
As presented in the proposed mechanism, more than
one molar equivalent of Co2(CO)8 is required for the
formation of (I), which thereafter leads to the formation
of urea- or azobenzene-derivative product. A critical
step is the oxidative addition process of 3 towards the
second molar of Co2(CO)8, that leads to the cleavage
of the metal–metal bond. In principle, it is unlikely to
break the cobalt–cobalt bond of a dppm bridged dico-
balt complex, Co2(CO)6(dppm) (4), at mild reaction
conditions. According to the proposed mechanism,
thereby, succeeding catalytic coupling reaction shall be
halted and resulted in the commonly observed alkyne
bridged dicobalt complex, [(dppm)Co2(CO)4(l-alkyne)].
Compound 4 was prepared from direct thermal reaction
of Co2(CO)8 with dppm [20]. Further reactions of 4 with
O
H
H
N
N
H
H
(OC)3Co
Co(CO)3
H
C
C
2
+
+
CH2 NH2
Co(CO)3 (OC)3Co
o
THF, 25 C, 3h
1
NH2
Co (CO)
2
2
8
H
C
H
C
H
N
C
C
2 H
NH2
C
Co(CO)3
Co
(CO)3
C
C
+
C
N
o
(OC)3Co
THF, 55 C, 4h
(CO)3Co
Co(CO)3
Co(CO)3
2
3a
Scheme 1.

Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
3451
H-C C C6H4NH2
H
Y
O
1 equiv. Co (CO)
+
2
8
C
O
C
[X] =
Co
Co
NH2[X]
C
3
O
C
O
C
Co (CO)
, coordination
C
+
2
8
O
O
oxidative addition
Y: CH2, C6H4
H
[X]
N
O
O
C
C
Co
C
O
HCo(CO)4
Co2(CO)8
+ 1/2
1/2
+
H2
C
O (I)
Route A
Course 1
Course 2
H
H
[X]
[X]
O
N
O
O
N
C
C
O
C
C
Co
Co
C
C
O
O
(II)
C
O
(VII)
+ NH [X]
3
2
H
[X]
[X]
H
O
N
O
O
C
C
N
C
Co
NH2[X]
O
O
C
C
O
Co
(VIII)
(III)
C
C
O
H
[X]
C
+ NH2[X]
[X]
3
N
O
C
H
O
H
Co
H
N
N
C
C
O
[X]
O
O
C
Co
CO
(IV)
[X]H2N
C
O
[X]
O
(IX)
H
N
C
O
C
N
C
Co
H
O
H
[X]
H
N
C
[X]
(V)
O
O
C
H
Co
H
[X]
H
N
C
O
C
O
N
[X]
H
(X)
C
O
O
N
C
C
reductive
[X]
Co
elimination
C
O
O
H
(VI)
reductive
elimination
O
[X]HN C NH[X]
1-like
+
CO
Co (CO)
H
HCo(CO)3
HCo(CO)4
1/2
+1 /2
8
+
2
2
Fig. 1. Proposed mechanism for the formation of 1.
1
propargylamine and 4-ethynylaniline at 25 °C for 24 h
gave alkyne bridged dicobalt complexes, [(dppm)Co2
(CO)4(l-HC„CCH2NH2)] (5) and [(dppm)Co2(CO)4
(l-HC„CC6H4NH2)] (6), respectively. (Scheme 2).
Both 5 and 6 were characterized by spectroscopic means
as well as X-ray structural determination.
As for the H NMR spectrum of 6 in CDCl3, it dis-
plays two sets of multiplet at 3.06 and 3.57 ppm which
are assigned for the two methylene protons of the bridg-
ing dppm. In contrast, there is only one set of triplet sig-
nal at 3.50 ppm for the similar protons being observed
for 5 in CDCl3. While changing the d-solvent to CD2Cl2,

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Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
Fig. 2. Proposed mechanism for the formation of 2.
H
NH2
Co(CO)2
H2
C
C
C
C
+ H C
C
NH
2
(CO)
(CO)
2Co
Ph2P
THF, 25¢J, 24h
PPh2
5
NH2
H
C
+
H C C
NH2
THF, 25¢J, 24h
2Co
Co(CO)2
O
O
O
C
Ph2P
C
PPh2
C
dppm
O
+
C
6
Co (CO)
Co
Co
2
8
C
Ph2P
O
C
O
PPh2
O
H
O
NH2
C
C
4
+ H C
C C NH2
THF, 25¢J, 24h
(CO)
Ph2P
2Co
Co(CO)2
PPh2
7
H
NH2
C
C
+ H C
C
NH2
(CO)
Ph2P
2Co
Co(CO)2
PPh2
THF, 25¢J, 24h
8
Scheme 2.

Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
3453
two sets of multiplets showed at 3.39 and 3.57 ppm for
5. These two sets of chemical shifts are separated away
further when the spectrum is taken at lower tempera-
ture, i.e. at ꢀ60 °C. Surprisingly, the expected proton
signals of the –CH2NH2 group do not appear in 1H
NMR. Previously, we observed a process of thermal
rocking of the bridging dppm in a closely related com-
pound [(dppm)Co2(CO)4{l-PPh2C„CPPh2}]. It was
found that the two sets of multiplet of the methylene
protons merged to one triplet while the rate of the back
and forth motion of the dppm was fast enough. In the
light of the previous observation, it is reasonable to state
that the thermal motion of the bridging dppm is greater
in 5 than that of 6. In the 31P NMR spectra, broad sig-
nals at 37.41 and 44.32 ppm are assigned for the phos-
phorous atoms of the bridging dppm of 5 and 6,
respectively. Suitable crystals of 5 and 6 were obtained
from mixture solvent (CH2Cl2/hexanes = 1:1) at 4 °C.
The structures of 5 and 6 were determined via X-ray dif-
fraction methods and the ORTEP drawings are pre-
sented in Figs. 3 and 4. As expected, the structures of
5 and 6 show that only alkyne bridged dicobalt com-
plexes rather than the previously observed coupling
products. These results are in acceptance with the pro-
posed mechanism which describes the formation of cou-
pling products 1 and 2 from the reaction of Co2(CO)8
with propargylamine and 4-ethynylaniline, respectively.
Further, the reaction of 6 with excess Co2(CO)8 at
25 °C for 24 h did not lead to the formation of azoben-
zene derivative. The bulkiness of the bridging dppm
might be the key factor for hindering further coupling
reaction.
Fig. 4. ORTEP drawing of 6. Hydrogen atoms are omitted for clarity.
dicobalt fragment to the bridged alkyne is greater for
the latter than the former compound, thus causes the
larger bending angle in 6 (see Diagram 1).
Reaction of 4 with propioamide (HC„CC(‚O)NH2)
and 1-ethynylcyclohexylamine (HC„CC6H10NH2) at
25 °C for 24 h gave [(dppm)Co2(CO)4(l-HC„CC(‚O)
NH2)] (7) and [(dppm)Co2(CO)4(l-HC„CC6H10NH2)]
(8), respectively. (Scheme 2). Both 7 and 8 were character-
1
ized spectroscopically. The H NMR spectrum of 7 dis-
Several selected structural parameters of 5 and 6 are
presented in Table 2 for the comparison. As shown in
Table 2, the major frameworks of these two compounds
are quite similar. The bond angles of C(1)–C(2)–C(3) are
129.3(10)° and 143.9(7)° for 5 and 6, respectively. It im-
plies that the electronic back-bonding process from the
plays two sets of multiplet at 3.45 and 3.59 ppm and two
sets of singlet at 5.51 and 5.95 ppm for the corresponding
methylene protons and protons of amide group, respec-
1
tively. For 8, the H NMR reveals two sets of multiplet
at 3.21 and 3.77 ppm for the matching methylene protons.
The signals of the corresponding cyclohexyl and amine
protons are merged into a broad peak ranges from 1.31
to 2.09 ppm. Once again, only alkyne bridged dicobalt
complexes were observed rather than the coupling
products.
For comparison, similar procedure was employed for
the reaction of propargylamine with bis-monodentate
phosphine coordinated dicobalt complex, (PPh3)(CO)3-
Co–Co(CO)3(PPh3). A coupling reaction is expected
from the above proposed mechanism since there no met-
als bridged ligand is present. Unfortunately, in contrast
to the previous cases, the reaction was resulted into the
formation of large amount of unidentified solid. Conse-
quently, there is no way to find out the reaction route
taken by these reactants. Repeatedly, we have found
that the reaction of di-substituted dicobalt hexacarbonyl
complexes, Co2(CO)6L2 (L: PPh3 or P(OMe)3), with var-
ious alkynes always lead to insoluble precipitation.
Fig. 3. ORTEP drawing of 5. Hydrogen atoms are omitted for clarity.

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Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
Table 1
Crystal data of 5, 6 and 14
5
6
14
Empirical formula
Formula weight
Crystal system
Space group
C32H22Co2NO4P2
669.38
Monoclinic
C2/c
C37H29Co2NO4P2
731.44
C20H15Co2N3O10
575.21
Monoclinic
P2(1)/c
15.8596(16)
12.0939(11)
19.578(2)
–
Monoclinic
P2(1)
˚
a (A)
35.109(4)
8.6187(10)
25.622(3)
–
15.2107(14)
9.8627(9)
15.9711(14)
–
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
130.206(2)
–
111.178(2)
–
99.500(2)
–
3
˚
V (A )
5921.3(13)
8
1.49
3519.0(4)
4
1.387
2363.1(4)
2
1.617
Z
Dcalc (Mg mꢀ3
)
˚
k (Mo Ka) (A)
0.71073
1.266
0.71073
1.078
0.71073
1.463
l (mmꢀ1
)
h Range (°)
1.60–26.06
2938
388
1.38–26.01
3025
415
2.44–26.04
6458
631
Observed reflections [F > 4r(F)]
Number of refined parameters
a
R1 for significant reflections
0.0575
0.1559
0.928
0.0604
0.1426
0.97
0.0493
0.1409
1.159
b
wR2 for significant reflections
Goodness-of-fitc
P
P
a
b
c
R1 = | (|Fo| ꢀ |Fc|)/| Fo||.
P
P
2
2
wR2 ¼ f ½wðF 2o ꢀ F c2Þ ꢁ= wðF 2oÞ g1=2; w ¼ 0:1253; 0:0866 and 0:0892 for 5; 6 and 14; respectively:
P
2
1=2
Goodness-of-fit ¼ ½wðF 2o ꢀ F 2c Þ =ðNreflections ꢀ NparametersÞꢁ
:
2.2. Reactions of Co2(CO)8 with alkynyl amines
H
C3
C1
C2
Direct treatment of 1-ethynylcyclohexylamine
(HC„CC6H10NH2) with one molar equivalent of
Co2(CO)8 in THF at 25 °C for 15 min gave an alkyne
bridged dicobalt complex, [Co2(CO)6(l-HC„CC6-
Co2
CX
Co1
1
H10NH2)] (9) (Scheme 3). The H NMR spectrum of 9
P2
CX: C20 for 5
C25 for 6
P1
displays a group of broad peaks ranged from 1.40 to
1.64 ppm. They are assigned for the 10 protons of the
cyclohexyl ring and for the two protons of the amine
group. Further, the reaction of 9 with excess Co2(CO)8
at 65 °C for 1 h did not show any sign of coupling prod-
uct formation. It is believed that the steric hindrance of
Diagram 1. Simplified structures for 5 and 6.
R:
H
NH2
NH2
C
C
THF, 25 ¢J, 15min
Co(CO)3
(CO)
3Co
9
R:
(OC)3
H
C
H
NH2
Co
(CO)3
N
C
C
C
NH2
+
C
N
C
H
Co2(CO)8 H C
C R
+
(OC)3
THF, 25 ¢J, 1h
Co(CO)3
(CO)3Co
Co (CO)3
10
11
O
O
C
H2C
C
NH2
R:
NH2
THF, 25 ¢J, 5h
(CO)
(CO)
3
3 Co
Co
Co
(CO)3
12
Scheme 3.

Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
3455
Table 2
Comparison of selected structural parameters of 5 and 6
fact that both the azobenzene compound 10 and al-
kyne bridged dicobalt complex 11 are coexisted in
the same batch of the reaction is noteworthy. Further,
the reaction of 11 with Co2(CO)8 under high pressure
of CO, 500 psi, at 25 °C for 30 h did not yield 10 or
urea-like coupling product. In contrast, the reaction of
3a under the same reaction conditions in fact yielded
2 even though no urea-like coupling product was ob-
served. Our previous works had demonstrated the
reaction of propiolamide, HC„CC(‚O)NH2, with
Co2(CO)8 gave a tricobalt methylidyne cluster, [Co3(-
CO)9(l3–CCH2C(‚O)NH2)] 12 [22]. Interestingly,
there was no alkyne bridged dicobalt complex being
observed. It is generally accepted that the formation
of this type of cluster via this route requires protonic
reaction condition, providing the extra hydrogen
comes from the acidic environs [23].
5
6
˚
Bond length (A)
Co(1)–C(2)
Co(1)–C(1)
Co(1)–P(1)
Co(1)–Co(2)
Co(2)–C(1)
Co(2)–C(2)
Co(2)–P(2)
P(1)–C(20)
P(2)–C(20)
P(1)–C(25)
P(2)–C(25)
C(1)–C(2)
C(2)–C(3)
N–C(3)
1.932(8)
1.939(8)
2.222(2)
2.4947(13)
1.942(9)
1.947(8)
2.2282(18)
1.815(6)
1.840(6)
–
2.005(7)
2.013(8)
2.2269(19)
2.4623(12)
1.873(8)
1.934(7)
2.2196(18)
–
–
1.822(6)
1.818(6)
1.366(10)
1.467(10)
–
–
1.341(13)
1.357(14)
1.220(16)
–
N–C(6)
1.389(10)
Bond angle (°)
2.3. Reactions of 8, 9, 11 with 2,4-dinitrofluorobenzene
C(2)–Co(1)–C(1)
C(2)–Co(1)–P(1)
C(1)–Co(1)–P(1)
C(2)–Co(1)–Co(2)
C(1)–Co(1)–Co(2)
P(1)–Co(1)–Co(2)
C(1)–Co(2)–C(2)
C(1)–Co(2)–P(2)
C(2)–Co(2)–P(2)
C(1)–Co(2)–Co(1)
C(2)–Co(2)–Co(1)
P(2)–Co(2)–Co(1)
C(20)–P(1)–Co(1)
C(20)–P(2)–Co(2)
C(25)–P(1)–Co(1)
C(25)–P(2)–Co(2)
C(2)–C(1)–Co(1)
C(2)–C(1)–Co(2)
Co(1)–C(1)–Co(2)
C(1)–C(2)–C(3)
C(1)–C(2)–Co(1)
C(3)–C(2)–Co(1)
C(1)–C(2)–Co(2)
C(3)–C(2)–Co(2)
Co(1)–C(2)–Co(2)
P(1)–C(20)–P(2)
P(2)–C(25)–P(1)
N–C(3)–C(2)
40.5(4)
137.1(3)
99.0(3)
50.2(2)
50.1(3)
96.27(6)
40.3(4)
98.8(3)
136.9(3)
49.9(2)
49.7(2)
97.28(6)
109.7(2)
108.8(2)
–
39.7(3)
137.5(2)
102.8(2)
50.0(2)
48.2(2)
92.10(6)
42.0(3)
93.5(2)
134.8(2)
53.2(2)
52.63(19)
98.55(5)
–
It is a frequent observation that the alkyne bridged
dicobalt complexes are oily in nature; thereby, it makes
the process of crystallization problematic. Besides, spect-
roscopic means such as the 1H NMR may not always pro-
vide unambiguous evidence concerning the existence of
an amino group in compounds. SangerÕs reagent, 2,4-dini-
trofluorobenzene, has been proved to be an effective agent
for labeling terminal amino group [24]. It was employed
here for examining the presence of a –NH2 group in 8, 9
and 11. Reactions of 8, 9 and 11 with one molar equivalent
of 2,4-dinitrofluorobenzene in THF at 25 °C for 48 h gave
[(dppm)Co2(CO)4-(l-HC„CC6H10NHC6H3(NO2)2)] (13),
[Co2(CO)6(l-HC„CC6H10NHC6H3(NO2)2)] (14) and
[Co2(CO)6(l-HC„CC6H4NHC6H3(NO2)2)] (15), respec-
tively (Scheme 4). Another reagent isothiocyanatobenzene
(Ph–N‚C‚S), that also has been proved to be an effec-
tive agent for spotting terminal amino group, was em-
ployed here to react with compound 9 and 11. Unlike
the previous works, the reactions were resulted in precip-
itated dark colored sulfidocobalt clusters.
–
108.2(2)
109.6(2)
69.8(4)
71.4(5)
78.6(3)
143.9(7)
70.4(4)
133.5(5)
66.6(5)
135.7(6)
77.4(3)
–
–
69.4(5)
70.0(6)
80.0(3)
129.3(10)
70.0(5)
135.1(8)
69.6(5)
141.6(9)
80.1(3)
111.4(3)
–
108.3(3)
–
All compounds were characterized by spectroscopic
means. Suitable crystals of 14 were obtained from mix-
ture solvent (CH2Cl2/hexanes = 1:1) at 4 °C and its
structure was determined by an X-ray diffraction method.
The structure of 14 reveals that the dinitrobenzene moi-
ety is joined with the deprotonated 9 and the bond angle
of C(3)–N(1)–C(9) is 130.0(3)° (Fig. 5). The hybridiza-
tion of the centered nitrogen is close to sp2 and indicates
the presence of a N–H bond. It is also evidenced by the
presence of corresponding signal appears at 9.16 ppm in
125.3(13)
bulky substituent play an important role in preventing
the formation of coupling products.
Reaction of 3-ethynlaniline, HC„CC6H4NH2, with
one molar equivalent of Co2(CO)8 in THF at 25 °C
for 1 h gave mostly alkyne bridged dicobalt complex,
[Co2(CO)6(l-HC„CC6H4NH2)] (11) [21] and small
amount of azobenzene compound, {[Co2(CO)6(l-
HC„C)]C6H4N‚}2 (10) (Scheme 3). Both com-
pounds were characterized by spectroscopic means.
The corresponding signals of the amine protons are
1
the H NMR spectrum. Although, some of the crystal
structures of the products from Scheme 4 are not avail-
able, it is safe to state that only alkyne bridged dicobalt
complexes were produced rather than the urea- or azo-
benzene-derivatives from the reaction as shown in
Scheme 3.
1
absent in H NMR of 10 which is in acceptance with
the chemical formula of the dimmerized product. The

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Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
NO2
H
H
NH2
C
C
THF 20ml
r.t., 48hrs
N
H
C
C
+
NO2
Co(CO)3
PPh2
(CO)3 Co
Ph2P
Co(CO)3
(CO)3 Co
Ph2P
8
PPh2
13
NO2
THF 20ml
r.t., 48hrs
NO2
H
F
H
+
NH2
Co(CO)3
C
C
C
N
C
C
H
O2N
NO2
14
(CO)3 Co
Co(CO)3
(CO)3 Co
9
NO2
H
H
C
THF 20ml
r.t., 48hrs
+
C
C
NH2
N
H
NO2
15
Co(CO)3
Co(CO)3
(CO)3 Co
(CO)3 Co
11
Scheme 4.
that the breaking of the Co–Co bond in Co2(CO)8 is
essential for the catalytic coupling reactions during the
formation of 1 or 2. In the cases of using 4 as dicobalt
source, only alkyne bridged dicobalt complexes were ob-
served. The steric hindrance of bulky substituent, as in
the case of 1-ethynylcyclohexylamine, might be blocking
the plausible coupling process. The preparation of an-
other azobenzene derivative, 10, from two primary
amines through a cobalt-mediated reaction was proved
successfully. The presence of amino groups in the prod-
ucts 8, 9 and 11 were verified by reacting with the San-
gerÕs reagent.
4. Experimental
4.1. General procedures
All operations were performed in a nitrogen flushed
glove box or in a vacuum system using freshly distilled
solvents. Separations of the products were performed
by Centrifugal Thin Layer Chromatography (CTLC,
˚
Fig. 5. ORTEP drawing of 14. Selected bond lengths (A) and bond
angles (°): Co(1)–C(1) 1.939(8), Co(1)–C(2) 1.993(7), Co(1)–Co(2)
2.477(2), Co(2)–C(1) 1.938(9), N(1)–C(9) 1.370(10), N(1)–C(3)
1.479(12), C(1)–C(2) 1.302(9), C(2)–C(3) 1.494(10), C(9)–N(1)–C(3)
130.8(7), Co(1)–C(1)–Co(2) 79.4(3), C(1)–C(2)–C(3) 143.8(7), N(1)–
C(3)–C(2) 109.8(7).
1
Chromatotron, Harrison model 8924). HNMR spectra
were recorded (Varian VXR-300S spectrometer) at
300.00 MHz and chemical shifts were reported in ppm
relative to internal CHCl3 or CH2Cl2. 31P and 13C
NMR spectra were recorded at 121.44 and 75.46
MHz, respectively. 1H NMR spectra of variable temper-
ature experiments were recorded on the same instru-
ment. Routine 1H NMR spectra were recorded at
Gemini-200 spectrometer at 200.00 MHz or Varian-
400 spectrometer at 400.00 MHz. IR spectra of sample
powder in KBr were recorded on a Hitachi 270-30 spec-
trometer. Mass spectra were recorded on JOEL
3. Summary
In this work, reactions of Co2(CO)8 or Co2
(CO)6(dppm) (4) with several selected alkynyl amines
were pursued. The experimental results are consistent
with the proposed reaction mechanism. It is observed

Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
3457
JMS-SX/SX 102A GC/MS/MS spectrometer. Elemental
analyses were recorded on Heraeus CHN-O-S-Rapid.
Accurate elemental analyses were precluded for the fol-
lowing compounds probably due to their chemical
labilities.
(CDCl3, d/ppm): 44.3(2P, dppm); IR (KBr/cmꢀ1): mNH2
1613(m), mCO 1985(s). Anal. Calc. for 6: N, 1.91; C,
60.76; H, 4.00. Found: N, 1.38; C, 60.26; H, 3.88%.
M.S. (m/z): 731(M+); m.p.: 89 °C.
4.1.5. Reaction of 4 with propioamide
4.1.1. Reaction of 4 with propargylamine
Dicobalt octacarbonyl Co2(CO)8 (0.358 g, 1.047
mmol) and dppm (0.405 g, 1.052 mmol) with 10 ml of
THF were taken into a 100 cm3 round bottomed flask
charged with magnetic stirrer. The solution was stirred
at 65 °C for 6 h and compound 4 was obtained. Without
further separation, a solution containing propioamide
(0.077g, 1.115 mmol) and 5 ml of THF was transferred
into the flask. The mixture was stirred at 25 °C for 8 h
and followed the similar purification processes. The
third band (red in color), [(dppm)Co2(CO)4(l-
HC„CC(‚O)NH2)] (7), was eluted by CH2Cl2 and
the yield is 56% (0.388 g, 0.568 mmol).
The preparative procedure of [Co2(CO)6(dppm)] (4)
was described elsewhere. Compound 4 (0.676 g, 1.008
mmol) and propargylamine (0.069 ml, 1.008 mmol) with
20 ml of THF were taken into a 100 cm3 flask. The solu-
tion was stirred at 25 °C for 24 h. Subsequently, the
resulting dark red solution was filtered through a small
amount of silica gel. Purification was carried out with
centrifugal thin-layer chromatography (CTLC). The
first band (red in color), [(dppm)Co2(CO)4(l-
HC„CCH2NH2)] (5), was eluted by CH2Cl2 and the
yield is 33% (0.226 g, 0.337 mmol).
4.1.2. Characterization of 5
4.1.6. Characterization of 7
1H NMR (CDCl3, d/ppm): 3.5(t, JP–H = 10.20 Hz,
2H, –CH2 of dppm), 6.11(s, 1H, HC„), 7.13–7.44(m,
20H, arene). 13C NMR (CDCl3, d/ppm): 39.81(t, JP–C
= 21.12 Hz, 1C, –CH2 of dppm), 53.41(1C, CH2NH2),
78.33(1C, HC„), 87.49(1C, C„CH), 128.34(d, JP–C
= 23.54 Hz, 2C, arene), 129.82(d, JP–H = 25.04 Hz, 2C,
arene), 131.00(t, JP–C = 5.85 Hz, 2C, arene), 136.98(t,
JP–C = 23.08 Hz, 1C, arene), 194.82(2C, CO),
203.09(1C, CO), 203.76(1C, CO). 31P NMR (CDCl3, d/
1H NMR (CDCl3, d/ppm): 3.45(m, 1H, –CH2 of
dppm), 3.59(m, 1H, –CH2 of dppm), 5.51(s, 1H, NH2),
5.87(t, JP–H = 4.02 Hz, 1H, HC„), 5.95(s, 1H, NH2),
7.12–7.41(m, 20H, arene). 13C NMR (CDCl3, d/ppm):
40.8(s, 1C, –CH2 of dppm), 67.0(1C, HC„C), 128.2–
132.5(24C, arene). IR (KBr/cmꢀ1): mCO 2062(s),
2033(s), 2004(s), 1969(s), 1648(C‚O). Anal. Calc. for
7: N, 2.05; C, 56.24; H, 3.69. Found: N, 2.11; C,
55.98; H, 3.74%. M.S. (m/z): 655 (M ꢀ CO)+.
ppm): 37.4(2P, dppm). IR (KBr/cmꢀ1): mNH 1646(m),
2
mCO 1976(s), 2005(s), 2025(s). Anal. Calc. for 5: N,
2.09; C, 57.42; H, 4.07. Found: N, 2.43; C, 55.72; H,
6.87%. M.S. (m/z): 669(M+); m.p.: 186 °C (dec. temp.).
4.1.7. Reaction of 4 with 1-ethynylcyclohexylamine
The similar reaction procedure was followed as
shown above. Dicobalt octacarbonyl Co2(CO)8 (0.347
g, 1.017 mmol) and dppm (0.389 g, 1.011 mmol) with
10 ml of THF were taken in a 100 ml round bottomed
flask charged with magnetic stirrer. The solution was
stirred at 65 °C for 6 h and compound 4 was yielded.
Without further separation, a solution containing 1-
ethynyl–cyclohexylamine (0.134 g, 1.087 mmol) and 5
ml of THF was transferred into the flask. The mixture
was stirred at 25 °C for 8 h and followed similar purifi-
cation processes. The third band (red in color),
[(dppm)Co2(CO)4(l-HC„CC6H10NH2)] (8), was eluted
by CH2Cl2 and the yield is 61% (0.4525 g, 0.614 mmol).
4.1.3. Reaction of 4 with 4-ethynylaniline
Following the similar procedure as shown above, 4
(1.176 g, 1.755 mmol) and 4-ethynlaniline (0.206 g,
1.755 mmol) with 20 ml of THF were placed into a
100 cm3 flask. The solution was stirred at 25 °C for 24
h and followed similar purification processes. The first
band
(purple
in
color),
[(dppm)Co2(CO)4(l-
HC„CC6H4NH2)] (6), was eluted by CH2Cl2 and the
yield is 41% (0.521 g, 0.712 mmol).
4.1.4. Characterization of 6
1H NMR (CDCl3, d/ppm): 3.06(m, 1H, –CH2 of
dppm), 3.57(m, 1H, –CH2 of dppm), 5.68(t, JP–H
= 7.61 Hz, 1H, HC„), 6.49(broad, 2H, NH2), 7.19–
7.43(m, 20H, arene, 2H, C6H4), 7.58(d, JH–H = 5.01
Hz, 2H, C6H4). 13C NMR (CDCl3, d/ppm): 40.87(t,
JP–C = 20.37 Hz, 1C, –CH2 of dppm), 72.85 (1C,
HC„), 128.10–128.3(m, 10C, arene), 129.35(2C, arene),
129.45(2C, arene), 136.47(1C, ipso of C6H4), 136.62(1C,
ipso of arene), 136.73(1C, ipso of arene), 136.86(1C, ipso
of arene), 136.99(1C, ipso of arene), 137.12(1C, ipso of
C6H4), 203.28(2C, CO), 207.32(2C, CO). 31P NMR
4.1.8. Characterization of 8
1H NMR (CDCl3, d/ppm): 1.31–2.09(m, 12H, C6H10
and NH2), 3.21(m, 1H, –CH2 of dppm), 3.75(m, 1H,
–CH2 of dppm), 5.72(s, 1H, HC„C), 7.23–7.47(m,
20H, arene). 13C NMR (CDCl3, d/ppm): 22.55(2C,
C6H10), 25.90(2C, C6H10), 41.35(1C, C6H10), 55.84(1C,
C6H10), 42.32(1C, dppm), 74.36(1C, HC„C),
117.61(1C, HC„C), 128.17–136.99(24C, arene),
203.93(2C, CO), 207.96(2C, CO). 31P NMR (CDCl3, d/
ppm): 42.3. IR (KBr/cmꢀ1): mCO 1956(s), 1987(s),
2014(s). Anal. Calc. for 8: N 1.90, C 60.24, H 4.78%.

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Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
Found: N 2.06, C 60.68, H 5.23%; M.S. (m/z): 721
(M ꢀ NH2)+.
146.50(s, 1C, ipso-arene), 199.44 (s, 6C, COs). IR
(KBr/cmꢀ1): mNH 1621(w), mCO 2023(s), 2055(s),
2093(s). Anal. Calc. for 11: N, 3.47; C, 41.72; H, 1.75.
Found: N, 3.49; C, 41.15; H, 1.74%. MS (FAB):
403(M+).
2
4.1.9. Reaction of Co2(CO)8 with HC„CC6H10NH2
Similar reaction procedures were employed as men-
tioned above. Co2(CO)8 (0.600 g, 1.755 mmol) and 1-
ethynylcyclohexylamine (0.237 ml, 1.755 mmol) with
20 ml of THF were placed into a 100 cm3 flask. The
solution was stirred at 25 °C for 15 min and followed
the similar purification processes. The first band (red-
brown in color) is [Co2(CO)6(l-HC„CC6H10NH2)] (9)
and the yield is 84% (0.607 g, 1.483 mmol).
4.1.14. Reaction of 8 with 2,4-dinitrofluorobenzene
Compound 8 (0.453 g, 0.614 mmol) and 2,4-dinitro-
fluorobenzene (0.116 g, 0.624 mmol) with THF 20 ml
were placed into a 100 cm3 flask. The solution was stir-
red at room temperature for 46 h. Purification was car-
ried out by using CTLC. The first band eluted was the
unreacted 8. The second band, (dppm)Co2(CO)4[l-
HC„CC6H10NH–C6H3(NO2)2] (13), was eluted with
mixed solvent (CH2Cl2:EA = 1:1) in the yield of 21%
(0.194 g, 0.215 mmol).
4.1.10. Characterization of 9
1H NMR (CDCl3, d/ppm): 1.40–1.64(m, 12H, C6H10
and NH2), 6.12(s, 1H, „CH). 13C NMR (CDCl3, d/
ppm): 22.40(2C, C6H10), 25.56(2C, C6H10), 42.41(1C,
C6H10), 55.27(1C, C6H10), 73.61(1C, HC„C),
110.20(1C, C„CH), 200.08(6C, CO). IR (KBr/cmꢀ1):
mCO 2017(s), 2051(s), 2093(s). Anal. Calc. for 9: N,
3.42; C, 41.10; H, 3.20%. Found: N, 2.96; C, 40.84; H,
3.73%. M.S. (m/z): 410 (M + 1)+.
4.1.15. Characterization of 13
1H NMR (CDCl3, d/ppm): 1.28–2.12, 2.61–2.64(m,
10H, C6H10), 3.05–3.14(m, 1H, –CH2 of dppm), 3.55–
3.64(m, 1H, –CH2 of dppm), 5.49(s, 1H, HC„), 7.18–
7.37(m, 20H, arene), 7.78(d, JH–H = 10.0 Hz, 1H, arene),
8.27(dd, JH–H = 9.61 Hz, JH–H = 2.40 Hz, 1H, arene),
9.17(t, JH–H = 2.80 Hz, 1H, NH). 13C NMR (CDCl3,
d/ppm): 22.4(2C, C6H10), 25.3(2C, C6H10), 40.1(1C,
C6H10), 61.8(1C, C6H10), 73.8(1C, HC„C), 117.3
(1C, HC„C), 123.8(1C, arene), 124.7(1C, arene),
126.7(1C, arene), 132.6(1C, arene), 138.1(1C, arene),
148.2(1C, arene), 128.3–131.5, 135.4–137.2(20C,
4.1.11. Reaction of Co2(CO)8 with 3-ethynlaniline
Co2(CO)8 (0.600 g, 1.755 mmol) and 3-ethynlaniline
(0.184 ml, 1.755 mmol) with THF 20 ml were placed into
a 100 cm3 flask. The solution was stirred at 25 °C for 1 h
and followed the similar purification processes. The first
band (brown in color), {[Co2(CO)6(l-HC„C)]C6-
H4N‚}2 (10) was eluted by mixture solvent (CH2Cl2:
hexane = 1:1) and the yield is 20% (0.139 g, 0.174 mmol,
based on Co2(CO)8) and the second band (purple in col-
or), Co2(CO)6(l-HC„C)C6H4NH2 (11) was eluted by
CH2Cl2, in the yield of 46% (0.324 g, 0.805 mmol).
arene) 203.1, 206.9(4C, CO). IR (KBr/cmꢀ1): mNO
2
1332(s), vCO 1960(s), 1987(s), 2020(s). Anal. Calc. for
13: N, 4.65; C, 57.16; H, 4.13. Found: N, 4.21; C,
54.31; H, 4.74%. M.S. (m/z): 903 (M+).
4.1.16. Reaction of 9 with 2,4-dinitrofluorobenzene
Compound 9 (0.784 g, 1.916 mmol) and 2,4-dinitro-
fluorobenzene (0.357 g, 1.916 mmol) with THF 20ml
were placed into a 100 cm3 flask. The solution was stir-
red at 25 °C for 48 h. Purification was carried out by
using CTLC and then washed with pure water. The first
band (dark red in color) Co2(CO)6[l-HC„CC6H10NH-
C6H3(NO2)2] (14), in the yield of 43% (0.479 g, 0.833
mmol).
4.1.12. Characterization of 10
1H NMR(CDCl3, d/ppm): 6.45(s, 1H, HC„), 7.51(t,
JH–H = 7.80 Hz, 1H, arene), 7.66(d, JH–H = 7.50 Hz, 1H,
arene), 7.88(d, JH–H = 8.10 Hz 1H, arene), 8.07(s, 1H,
arene). 13C NMR(CDCl3, d/ppm): 72.66(s, 1C, HC„C),
88.75(s, 1C, C„CH), 122.13(s, 1C, arene), 124.69(s, 1C,
arene), 129.70(s, 1C, arene), 132.88(s, 1C, arene),
138.92(s, 1C, ipso-arene), 152.85(s, 1C, ipso-arene),
199.26(s, 6C, COs). IR (KBr/cmꢀ1): mCO 2022(s),
2057(s), 2096(s). Anal. Calc. for 10: N, 3.49; C, 41.93;
H, 1.26. Found: N, 3.23; C, 40.28; H, 3.59%. MS
(FAB): 803 (M + 1)+.
4.1.17. Characterization of 14
1H NMR (CDCl3, d/ppm): 1.33–1.89, 2.47–2.51(m,
10H, C6H10), 6.20(s, 1H, HC„C), 7.42(d, JH–H = 9.30
Hz, 1H, arene), 8.30(dd, JH–H = 9.45 Hz, JH–H = 2.10
Hz, 1H, arene), 9.01(s, 1H, arene), 9.16(d, JH–H = 2.40
Hz, 1H, NH). 13C NMR (CDCl3, d/ppm): 21.97(2C,
C6H10), 24.95(2C, C6H10), 39.99(1C, C6H10), 59.97(1C,
C6H10), 73.61(1C, HC„C), 100.00(1C, C„CH),
116.13(1C, arene), 124.70(1C, arene), 129.19(1C, arene),
131.46(1C, arene), 136.24(1C, arene), 147.04(1C, arene),
4.1.13. Characterization of 11
1H NMR(CDCl3, d/ppm): 3.69(s, 2H, NH2), 6.34(s,
1H, HC„), 6.63(d, JH–H = 6.60 Hz, 1H, arene), 6.85(s,
1H, arene), 6.95(d, JH–H = 7.20 Hz, 1H, arene), 7.12(t,
JH–H = 7.50 Hz, 1H, arene). 13C NMR(CDCl3, d/
ppm): 72.58(s, 1C, HC„C), 90.50(s, 1C, C„CH),
115.19(s, 1C, arene), 116.54(s, 1C, arene), 120.90(s, 1C,
arene), 129.57(s, 1C, arene), 138.20(s, 1C, ipso-arene),
199.05(6C, CO). IR (KBr/cmꢀ1): mNO 1337(s), 1517(s),
2

Fung-E Hong et al. / Journal of Organometallic Chemistry 689 (2004) 3449–3460
3459
mCO 2054(s), 2097(s). Anal. Calc. for 14: N, 7.31; C,
41.76; H, 2.63. Found: N, 7.52; C, 42.16; H, 3.08%;
Appendix A. Supplementary material
m.p. = 142 °C (dec. temp.).
Crystallographic data for the structural analysis
have been deposited with the Cambridge Crystallo-
graphic Data Center, CCDC Nos. 223184, 223185
and 223186 for 5, 6 and 14, 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). Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2004.07.047.
4.1.18. Reaction of 10 with 2,4-dinitrofluorobenzene
Compound 10 (0.248 g, 0.616 mmol) and 2,4-dinitro-
fluorobenzene (0.115 g, 0.616 mmol) with THF 20ml
were placed into a 100 cm3 flask. The solution was stir-
red at 25 °C for 48 h. Purification was carried out by
using CTLC and then washed with pure water. The first
band (dark red in color) Co2(CO)6[(l-HC„C)
C6H4NHC6H3(NO2)2] (15), in the yield of 46%
(0.0.161 g, 0.283 mmol).
References
4.1.19. Characterization of 15
1H NMR (CDCl3, d/ppm): 6.40(s, 1H, HC„C), 7.22–
7.26(m, 2H, arene), 7.45–7.51(m, 3H, arene), 8.17(d, JH–H
= 9.00 Hz, 1H, arene), 9.19(s, 1H, NH), 10.00(s, 1H,
arene). 13C NMR (CDCl3, d/ppm): 72.61(1C, HC„C),
87.66(1C, C„CH), 116.01(1C, arene), 124.12(1C, arene),
124.70(1C, arene), 126.25(1C, arene), 129.19(1C, arene),
129.95(1C, arene), 130.82(1C, arene), 131.42(1C,
arene), 137.28(1C, arene), 137.71(1C, arene), 140.40(1C,
arene), 146.72(1C, arene), 198.94(6C, CO). IR (KBr/
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