Novel acetylene-linked di-cobalt and tetra-cobalt carbonyl clusters

Article abstract of DOI:10.1016/S0022-328X(99)00399-X

{Co₂(CO)₆} groups were attached to p-diethynylbenzene-based acetylenes giving complexes of general formula [{Co₂(CO)₆}(μ₂-η^2:2-RC ₂C₆H₄C₂R′)] ((4): R=R′=H; (4a): R=SiMe₃, R′=H; (4b): R=R′=SiMe₃); [{Co₂(CO)₆}₂(μ₄-η ^2:2:2:2-RC₂C₆H₄C ₂R′)] ((3): R=R′=H; (3a): R=SiMe₃, R′=H; (3b): R=R′=SiMe₃); [{Co₂(CO)₆}₄(μ₈-η ^{2:2:2:2:2:2:2:2}-R₂C₆H₄C ₂C₂C₆H₄C₂R)]((5): R=H; (5b):R=SiMe₃). The addition of Co₄(CO)₁₂ to p-diethynylbenzene and to 4 was also investigated, producing [{Co₄(CO)₈(μ-CO)₂}(μ₄-HC ₂C₆H₄C₂H)] (6) and [{Co₂(CO)₆}{(Co₄(CO)₈(μ-CO) ₂}(μ₈-HC₂C₆H₄C ₂H)] (7). The syntheses of the acetylenic derivatives of C₆₀ [(trimethylsilyl)ethynyl]hydrofullerene[60] (8a) and (phenylethynyl)hydrofullerene[60] (9) and the new ligand [(trimethylsilyl)diethynylbenzene]hydrofullerene[60] (10a) were performed and the resulting acetylenes were reacted with dicobaltoctacarbonyl giving the corresponding complexes [(trimethylsilyl)(dicobalthexacarbonyl)ethynyl]hydrofullerene[60] (11a), (phenylethynyl)(dicobalthexacarbonyl)hydrofullerene[60] (12) and [(trimethylsilyl)bis(dicobalthexacarbonyl)diethynylbenzene] (13a). The reaction of 1-bromo-3,5-diethynylbenzene and 1,3,5-triethynylbenzene with dicobaltoctacarbonyl resulted in the formation of [HC₂{Co₂(CO)₆}]₂C₆H ₂Br (16) and [HC₂{Co₂(CO)₆}]₂C₆H ₃ (15) as expected. Crystals of 3a, 3b, 4, 4b, 15 and 16 suitable for single-crystal X-ray diffraction were grown and the molecular structures of these compounds are discussed.

Full text of DOI:10.1016/S0022-328X(99)00399-X

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 589 (1999) 157–167
Novel acetylene-linked di-cobalt and tetra-cobalt carbonyl clusters
Sylvia M. Draper a,*, Marika Delamesiere a, Elise Champeil a, Brendan Twamley a,
Janice J. Byrne a, Conor Long b
a Chemistry Department, Trinity College Dublin, Dublin 2, Ireland
b The School of Chemical Sciences, Dublin City Uni6ersity, Dublin 9, Ireland
Received 15 November 1998; received in revised form 30 June 1999
Abstract
{Co2(CO)6} groups were attached to p-diethynylbenzene-based acetylenes giving complexes of general formula [{Co2(CO)6}(m2-
h
2:2-RC2C6H4C2R%)] ((4): R=R%=H; (4a): R=SiMe3, R%=H; (4b): R=R%=SiMe3); [{Co2(CO)6}2(m4-h2:2:2:2-RC2C6H4C2R%)]
((3): R=R%=H; (3a): R=SiMe3, R%=H; (3b): R=R%=SiMe3); [{Co2(CO)6}4(m8-h2:2:2:2:2:2:2:2-R2C6H4C2C2C6H4C2R)]((5): R=
H; (5b):R=SiMe3). The addition of Co4(CO)12 to p-diethynylbenzene and to 4 was also investigated, producing [{Co4(CO)8(m-
CO)2}(m4-HC2C6H4C2H)] (6) and [{Co2(CO)6}{(Co4(CO)8(m-CO)2}(m8-HC2C6H4C2H)] (7). The syntheses of the acetylenic
derivatives of C60 [(trimethylsilyl)ethynyl]hydrofullerene[60] (8a) and (phenylethynyl)hydrofullerene[60] (9) and the new ligand
[(trimethylsilyl)diethynylbenzene]hydrofullerene[60] (10a) were performed and the resulting acetylenes were reacted with dicobal-
toctacarbonyl giving the corresponding complexes [(trimethylsilyl)(dicobalthexacarbonyl)ethynyl]hydrofullerene[60] (11a),
(phenylethynyl)(dicobalthexacarbonyl)hydrofullerene[60] (12) and [(trimethylsilyl)bis(dicobalthexacarbonyl)diethynylbenzene]
(13a). The reaction of 1-bromo-3,5-diethynylbenzene and 1,3,5-triethynylbenzene with dicobaltoctacarbonyl resulted in the
formation of [HC2{Co2(CO)6}]2C6H2Br (16) and [HC2{Co2(CO)6}]2C6H3 (15) as expected. Crystals of 3a, 3b, 4, 4b, 15 and 16
suitable for single-crystal X-ray diffraction were grown and the molecular structures of these compounds are discussed. © 1999
Elsevier Science S.A. All rights reserved.
Keywords: Polynuclear; Metal carbonyls; Ethynylbenzene; Non-linear optics
P-conjugated polyynes are attractive materials for
non-linear optics [6]. Free polyynes are constructed via
1. Introduction
stepwise multi-coupling reactions but are generally un-
The interaction of alkynes with Co2(CO)8 is well
stable [7]. Previous researchers have used metal–
documented [1]. There has been a recent resurgence of
acetylene complexes as building blocks in the
interest in the resulting complexes, [{Co2(CO)6}(m,h2:2
-
generation of stabilized polyynes [8]. In this work we
adopted di- and tri- ethynylbenzene as the metal car-
bonyl linking unit. The benzene ring is a suitable alkyne
spacer because it forms an electron-rich p-conjugated
system, which can be extended in a linear (disubsti-
tuted) or network (trisubstituted) fashion. Recent ad-
vances in the syntheses of fullerene–acetylenes
suggested C60 as an alternative source of conjugated C6
rings [9].
RC2R%)]. This is partly due to the use of similar com-
pounds in the formation of cyclopentenones
(Pauson–Khand reaction) [2], in the generation of [2+
2+2] cycloadditions (via an intramolecular Heck reac-
tion) [3] and in the stabilization of propargyl cations
(Nicholas carbocations) [4]. There is considerable scope
for modifying these transformations by changing the
cobalt source (e.g. Co4(CO)12) [11] or the substituents
on the alkyne [5]. This work represents the first in a
series of studies on the synthesis and photochemistry of
modified cobalt carbonyl complexes.
2. Results and discussion
Co2(CO)8 addition to ethynyls can be achieved by
stoichiometric addition of the reagents, in CH2Cl2, and
* Corresponding author: Fax: +353-1-6712826.
E-mail address: smdraper@tcd.ie (S.M. Draper)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00399-X

158
S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
The addition of Co4(CO)12 to p-diethynylbenzene (1)
and to the complex [{Co2(CO)6}(m4-h2:2:2:2-HC2C6H4-
C2H)] (4) was also investigated, producing [{Co4(CO)8-
(m–CO)2}(m4–HC2C6H4C2H)] (6) and [{Co2(CO)6}-
in most cases under an inert atmosphere at room
temperature (see Scheme 1). In the process two equiva-
lents of CO are lost, allowing the retention of the 18 e−
count in the alkynyl products. In this work,
{Co2(CO)6} groups were attached to substituted di-
ethynylbenzene giving complexes [{Co2(CO)6}(m4-
{(Co4(CO)8(m–CO)2}(m8–HC2C6H4C2H)]
(7)
(see
Scheme 2). These derivatives are extremely air-sensitive
and can only be isolated by inert atmosphere chro-
matography and work-up.
h
2:2:2:2-RC2C6H4C2R%)]
((4):
R=R%=H;
(4a):
R=SiMe3, R%=H; (4b): R=R%=SiMe3). The addi-
tion of two {Co2(CO)6} units to substituted diethynyl-
Alternative ligand sets were examined. These in-
cluded the trisubstituted benzene system, 1,3,5-tri-
ethynylbenzene (14) and 1-bromo-3,5-ethynylbenzene
(14c) and the acetylenic derivatives of C60 [(trimethylsi-
lyl)ethynyl]hydrofullerene[60] (8a), (phenylethynyl)-
benzene
gave
[{Co2(CO)6}2(m8-h2:2:2:2:2:2:2:2-RC2C6-
H4C2R%)] ((3): R=R%=H; (3a): R=SiMe3, R%=H;
(3b): R=R%=SiMe3). Coupled diethynylbenzene gave
the corresponding substituted compounds 5 and 5b.
Scheme 1. Schematic representation of the complexes containing exclusively {Co2(CO)6} units. The C atom numbers are consistent with the NMR
assignments and the X-ray crystallography atom labelling.
Scheme 2. Schematic representation of the complexes containing {Co4(CO)8(m-CO)2} units. The bridging carbonyl ligands have been removed for
clarity. The atom labels are consistent with the NMR assignments.

S.M. Draper et al. / Journal of Organometallic Chemistry 589(1999) 157–167
159
hydrofullerene[60] (9), [(trimethylsilyl)diethynylben-
zene]hydrofullerene[60] (10a). These were reacted with
Co2(CO)8 and the resulting fully coordinated complexes
were spectroscopically characterised.
empty d orbitals on the Si atom [12]. These downfield
shifts are no longer observed on metal coordination e.g.
5b. It would appear that formation of the dimetallate-
trahedrane alters the electronic environment of Rꢀ13C1.
As expected, the other carbon signal on which it has a
significant influence is 13C3, which does not form part
of the dimetallatetrahedrane core but is directly at-
tached to it.
2.1. Infrared spectra
The solution IR spectra in hexane of all cobalt
carbonyl compounds gave rise to the expected strong
CꢀO absorptions in the carbonyl region. In particular,
the IR spectra of 4, 4a, 4b and 11a show a similar and
characteristic pattern for terminal carbonyl stretches as
was observed previously for [{Co2(CO)6(m,h2-RC2R%)]
complexes [10].
For the complexes that possess more than one
dimetallatetrahedrane core, the IR carbonyl region re-
sults from the superposition of the IR carbonyl stretch-
ing bands corresponding to each core. There is little
difference in the overall carbonyl pattern mentioned
above. However, the presence of two bands arising
from the totally symmetric CꢀO stretching vibration
(w1CO) for complexes 3a, 5, 5b and 13a confirms the
presence of more than one type of dimetallatetrahe-
drane core in these molecules.
The IR spectra of 6 and 7 were conducted in Nujol
using mounting plates designed for air-sensitive com-
pounds. Terminal and bridging CꢀO bands are visible
and the carbonyl pattern for 7 is similar to the one
previously published for [{Co4(CO)8(m-CO)2}(m4-
HC2H)] (n-heptane) [11], indicating a similar coordina-
tion mode of the alkyne.
The 13C chemical shifts of the carbonyls in the
[{Co2(CO)6}(m-RC2R%)] complexes appear as one signal
at around l 199, suggesting that they are rapidly inter-
changing on the NMR scale. The complexes containing
two different types of {Co2(CO)6} cores exhibit in their
13C-NMR spectra two carbonyl signals.
For 6 and 7, each 13C-NMR spectrum only exhibits
six peaks. The 13C chemical shifts of the carbon atoms
Hꢀ13C113C2ꢀAr coordinated to a {Co4(CO)10} group
could not be detected. This is thought to be a relaxation
effect.
2.3. Description of the molecular structures
Crystallisation of products 3a, 3b, 4, 4b, 15 and 16
from hexane–CH2Cl2 solutions at −25°C gave light-
red to dark-red air-stable crystalline solids. The molecu-
lar structures of 3a, 4b, and 16 are shown in Figs. 1–3,
respectively. The core structure of one molecule of 15
can be seen in Fig. 4 and results from an incomplete
data set collected on a plate-like crystal of this
compound.
The interaction of the Co2(CO)6 units lengthens the
alkyne bond, as is consistent with the loss of CꢁC bond
character resulting from the delocalisation of electron
density onto the Co2 unit (see Table 1). The deviation
from sp hybridisation on metallisation is also clearly
seen in the pivotal angles C(6)ꢀC(7)ꢀC(8) (3a: 142.9(4)°;
3b: 142.2(2)°; 4b: 141.6(3)°) and C(3)ꢀC(2)ꢀC(1) (3a:
142.5(4)°; 4: 142.2(3)°: 16: 141.1(8)°) about C(7) and
C(2). These angles are similar to that already reported
for [{Co2(CO)6}2(H2C2C6H4C2H)] (141.9(7)°) and imply
that this angle is independent of the substituents at-
tached to the phenyl ring within crystallographic error.
The CꢀC bond is twisted out of the plane containing
the aryl ring in each case. The maximum bend out of
the plane defined by the benzene ring for the diethynyl
benzene systems is observed in 3a for the trimethylsilyl-
substituted portion of the alkyne (C(8)ꢀC(7)ꢀC(6)ꢀC(5)
163.3°, C(8)ꢀC(7)ꢀC(6)ꢀC(4) 18.0°) as opposed to the
2.2. NMR spectroscopy
The coordination of the alkynes to {Co2(CO)6} is
evident from the downfield shift of the terminal protons
in the 1H-NMR spectra [10]. Clearly this does not relate
to the fullerenyl protons of 8a, 9 and 10a, which are in
a different electronic environment and experience an
upfield shift from l 7.2 to 6.8 upon coordination. In
addition, the carbon Hꢀ13C1ꢁCꢀAr experiences a shield-
ing effect in 13C-NMR, whereas the carbon
HꢀCꢁ13C2ꢀAr signal is moved downfield (e.g. see com-
plexes 4a, 5, 6).
1
A Coloc long-range H-13C-COSY was performed on
p-trimethylsilyl diethynylbenzene (1a) (CDCl3) in order
to determine the resonances of the acetylenic carbons.
The signal at l 104.6 was assigned to the carbon 13C2
atom next to the phenyl ring, whereas the carbon 13C1
attached to the Si(CH3)3 group resonates at l 96.2.
Comparison of the signals of R-13C1 and RꢀC1ꢁ13C2
(R=H, Si(CH3)3) suggests that the Si(CH3)3 group is
electron withdrawing when attached to an aromatic
ring. It has been suggested that this results from back-
donation Si’Cp that originates from interactions be-
tween the perpendicular acetylenic p-orbitals and the
proton-terminated
portion
C(1)ꢀC(2)ꢀC(3)ꢀC(10)
166.8°, C(1)ꢀC(2)ꢀC(3)ꢀC(4) 14.2°). The free alkyne
unit in 4b and 4 retains its linearity as expected and the
relevant bond lengths are consistent with the retention
of significant triple-bond character C(1)ꢀC(2) (4:
1.155(5); 4b: 1.196(5)). The hydrogen-terminated alkyne
bond is considerably shorter than in the trimethylsilyl
case, but within crystallographic error this does not

160
S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
Fig. 1. ORTEX drawing of the molecular structure of 3a (thermal ellipsoids have been drawn at 40% probability level, hydrogen atoms have been
omitted for clarity).
Fig. 2. ORTEX drawing of the molecular structure of 4b (thermal ellipsoids have been drawn at 40% probability level, hydrogen atoms have been
omitted for clarity).
HꢀCꢀCo bonds (e.g. C(1)ꢀCo in 3a) are on average
shorter than those close to the phenyl ring (e.g.
C(2)ꢀCo in 3a). The two Co2C2 tetrahedranes in the
molecular structure of 16 also illustrate this feature.
However, those dimetallatetrahedranes terminated by a
SiMe3 group show a reversal of this trend, the CꢀCo
bonds next to the phenyl ring being the shortest (e.g.
C(7)ꢀCo in 3a). In addition the asymmetry of the
dimetallatetrahedranes is most clearly seen in the dis-
parity of the (Ar)CꢀCo bond lengths, which show a
long–short relationship.
significantly affect the length of the adjacent C(2)ꢀC(3)
bond (4b: 1.442(5); 4: 1.450(4)).
The CoꢀCo bond lengths are shorter than that ob-
,
served in the parent carbonyl (2.52 A) and lie in the
,
range 2.46–2.48 A [13]. This observation agrees with
previously reported dicobalt systems that are bridged
by perpendicular alkynes [14]. A common feature of all
the molecular structures obtained is the presence of
distorted Co2C2 cores. An interesting feature of these
cores is the nature of the asymmetry of the Co–C
distances. Unlike the Co–Co bonds, these are sensitive
to the substituents on the alkyne. For all systems
containing a terminal proton on the alkyne the
As expected, 3b which is symmetrically substituted
has a crystallographic centre of symmetry that lies at

S.M. Draper et al. / Journal of Organometallic Chemistry 589(1999) 157–167
161
of 15 is sufficient to illustrate the manner in which the
system can accommodate three metallahedrane units.
Interestingly there is no three-fold axis of rotation
about the centre of the benzene ring. In fact the bent
three-legged structure in which the legs radiate from the
central ring is reminiscent of a ‘hopping’ triskelion.
3. Conclusions
The selective synthesis of [{Co2(CO)6}(m,h2-
SiMe3C2C6H4C2H)] (4a) indicates that the addition of
{Co2(CO)6} groups to alkynes can be controlled.
Clearly one of the factors that influences the degree and
position of the metallisation is the bulk of the sub-
stituents on the alkyne. The work described details the
structural affects associated with proton or trimethylsi-
lyl termination of the alkyne, but a number of sub-
stituents can be envisaged [16], e.g. ferrocene or
fullerene.
It has recently been shown that non-polar molecules
with a three-fold rotation symmetry can have non-zero
i values [17]. As such we are interested in the synthesis
of polymers derived from 1,3,5-triethynylbenzene. Mul-
tiple acetylation of C60 would generate a three-dimen-
sional carbon-rich framework on which to support
metal complexes. Possible targets are the polymers
derived from Fullerene[60] and p-diethynylbenzene or
1,3,5-triethynylbenzene (see Scheme 3). We are in the
process of examining the non-linear optical responses of
such systems. In addition we intend to exploit pho-
Fig. 3. ORTEX drawing of the molecular structure of 16 (thermal
ellipsoids have been drawn at 40% probability level, hydrogen atoms
have been omitted for clarity).
the centre of the aryl ring. The overall geometry of the
system is very similar to that already reported for 3
[10].
A number of systems have recently reported molecu-
lar structures of metallised derivatives of 1,3,5-tri-
ethynylbenzene [15]. However, none possesses the
characteristic distorted metallahedranes reported in this
work. The molecular structure of 16 contains two dis-
tinct dimetallatetrahedranes that twist out of the plane
associated with the benzene ring. The respective dihe-
dral angles are C(10)ꢀC(9)ꢀC(7)ꢀC(6) 167.6°,
C(10)ꢀC(9)ꢀC(7)ꢀC(8) 12.5°) and C(1)ꢀC(2)ꢀC(3)ꢀC(8)
161.0°, C(1)ꢀC(2)ꢀC(3)ꢀC(4) 19.8°. The core structure
Fig. 4. SHAKAL drawing of the core molecular structure of 15. Only one of the two molecules contained in the unit cell is depicted.

162
S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
Table 1
,
Bond lengths (A) present in the different ‘Co2C2’ cores of 3a, 3b, 4, 4b, 16
Complexes
3a
4
Co1ꢀCo2
2.4718(10)
2.4649(8)
2.485(2)
C2ꢀC1ꢀH
1.345(6)
1.325(5)
1.327(12)
(H)C1ꢀCo
1.953(5)
1.949(3)
(Ar)C2ꢀCo
1.977 [4]
1.983 [2]
1.972[9]
1.950(5)
1.946(5)
1.942(9)
1.962 [4]
1.953 [3]
1.940[9]
16
1.954(10)
Co3ꢀCo4
2.4820(10)
2.4828(5)
2.4733(9)
C7ꢀC8(SiMe3)
1.333(6)
1.334(3)
(Me3Si)C8ꢀCo
1.993(4)
1.996(2)
(Ar)C7ꢀCo
1.982 [4]
1.984 [2]
1.966 [3]
3a
3b
4b
1.989(4)
1.993(2)
1.993(4)
1.957 [4]
1.957 [2]
1.955 [3]
1.341(5)
1.996(3)
Co3ꢀCo4
2.471(2)
C9ꢀC10(H)
1.325(12)
(H)C10ꢀCo
1.947(10)
(Ar)C9ꢀCo
1.938[9]
16
1.931(10)]
1.975[8]
Scheme 3. Polymers derived from Fullerene[60] and p-diethynylbenzene or 1,3,5-triethynylbenzene (R=alkyl or aryl chain).
tolytic carbonyl loss from dicobalt hexacarbonyl sys-
tems incorporating phenyl or diphenyl acetylene: the
first step in the normally thermally initiated Pauson–
Khand reaction [18].
4.2. Syntheses of the ligands
The ligands p-diethynylbenzene (1), 1,3,5-triethynyl-
benzene (14) and 1-bromo-3,5-ethynylbenzene (14a)
were prepared following the literature procedures [19].
The trimethylsilyl derivatives (1a) and p-bis(trimethylsi-
lyl)diethynylbenzene (1b) were obtained by reacting 1
with n-BuLi in THF at −78°C, in 1:1 and 1:2 ratios,
respectively, followed by treatment with Me3SiCl. The
three ligands were purified through controlled sublima-
tion under reduced pressure. p-Trimethysilyldiethynyl-
benzene (1a) was coupled under Hay’s conditions [20]
(CuCl, TMEDA, acetone) to give the protected dimer
2b. Subsequent treatment of the later with anhydrous
potassium carbonate in anhydrous methanol at 25°C
afforded the deprotected dimer bis(p-diethynylbenzene)
(2) (see Scheme 4). The detailed experimental condi-
tions used are given below.
4. Experimental
4.1. General considerations
Infrared measurements were performed on a Perkin–
Elmer Paragon 1000 FT-IR spectrophotometer. NMR
measurements were performed on a Bruker MSL 300
FT spectrometer or on a Bruker DPX 400 FT spec-
trometer. 1H-NMR (300 and 400 MHz, respectively)
were standardised with respect to TMS set at l 0.0.
13C-NMR spectra (75 and 100 MHz, respectively) were
standardised with respect to TMS. UV–vis spectra were
performed on a Unicam UV–vis UV4 spectrometer.
The FAB mass spectra were obtained using a VG
Autospec instrument using 3-NOBA as matrix. The
melting points were recorded using a Griffin melting
point apparatus.
4.2.1. [Me3SiCꢁCC6H4CꢁC]2 (2b)
Acetone (25 ml), TMEDA (2 ml, 1% in acetone, 0.13
mmol) and CuCl (13 mg, 0.13 mmol) were stirred at
28°C while oxygen was bubbled through the solution.
After 15 min, the colour of the solution changed from
colourless to green. (Trimethylsilyl)diethynylbenzene
(0.525 g, 2.65 mmol) was dissolved in acetone (20 ml)
and added drop-wise to the above mixture.
The reactions involving organometallic compounds
were carried out using standard Schlenk line techniques
under an atmosphere of argon. All solvents were dried
and degassed before use.
Bis[(trimethylsilylsilyl)diethynylbenzene]
precipitated

S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
163
from the solution during strong stirring and as oxygen
4.2.3. 1-Hydro-9-[(trimethylsilyl)diethynylbenzene]-
fullerene[60] (10a)
was still bubbling through the solution over 3 h. The
white precipitate was filtered, washed with acetone,
with dilute HCl (1 ml of concentrated HCl in 20 ml
H2O) and acetone. The product was dissolved in ben-
zene, the organic layer was washed with water, and
removal of the solvent yielded bis[(trimethylsi-
lyl)diethynylbenzene] as a yellowish shiny and flaky
powder (0.421 g, 81%): m.p.=218–222°C (dec.). TLC:
A 0.28 M solution of [(trimethylsilyl)diethynyl-
benzene]lithium (IV) was prepared by first dissolving
(trimethylsilyl)diethynylbenzene (0.170 mg, 0.86 mmol)
into THF (2.3 ml). This solution was left stirring at
−78°C for 5 min before n-BuLi (0.51 ml, 1.54 N, 0.79
mmol) was added to it drop-wise. The mixture was left
stirring for 40 min at 0°C and 5 min at room tempera-
ture. [(Trimethylsilyl) diethynylbenzene]lithium (1 ml,
0.29 mmol) was added drop-wise to a vigorously stirred
suspension of C60 (35 mg) in THF (35 ml) over 10 min.
The resulting dark-green solution was left stirring for
an extra 10 min, and was then quenched with
CF3COOH (0.3 ml, 3.9 mmol) to give a brown/orange
solution. Extraction in cyclohexane of the residue, fol-
lowed by flash chromatography (SiO2, cyclohexane)
afforded C60 (3 mg, 9%) and 1-hydro-9-[(trimethylsi-
lyl)diethynylbenzene]fullerene[60] (20 mg, 45%, Rf 0.3).
The presence of the bis adduct was indicated by TLC
(Rf 0.2). M.p.\360°C. 1H-NMR (CDCl3/CS2 (1:1), 400
1
Rf 0.6 (Al2O3, hexane). H-NMR (CDCl3, 300 MHz) :l
3
3
7.43 (d, J=9 Hz, 4H, H4/H5), 7.46 (d, J=9 Hz, 4H,
H4/H5), 0.27 (s, 18H, HCH3). 13C-NMR (CDCl3, 75
MHz): l 132.26/131.92 (C4/C5), 104.26 (C2), 124.00
(C3), 121.56 (C6), 97.33 (C1), 81.96 (C7), 75.55 (C8),
−0.14 (CCH ). IR (KBr, cm−1): 2957 (m), 2896 (w),
w(CꢀH aryl);32152 (m), w(CꢁC); 1492 (m), w(CꢂC aryl);
1254 (m), w(SiꢀMe). Anal. Calc. for C26H26Si2 (394.66):
C, 79.1; H, 6.6. Found: C, 79.2; H, 6.9.
4.2.2. [HCꢁCC6H4CꢁC]2 (2)
Bis[(trimethylsilyl)diethynylbenzene] (0.294 g, 0.75
mmol) was treated with K2CO3 (81 mg, 0.59 mmol) in
MeOH (30 ml) with strong stirring for 5 days. MeOH
was removed under vacuum, and the residue was
treated with NaHCO3 (150 mg) in water (20 ml) for 15
min. Bis[diethynylbenzene] was filtered, washed with
water, cold chloroform and acetone. It was isolated as
a dark yellow powder (0.168 g, 90%). M.p.\360°C.
TLC: Rf 0.2 (SiO2, hexane). IR (KBr, cm−1): 3267 (m),
w(ꢁCꢀH); 2961 (w), w(HꢀC aryl); 2151 (w), w(C7ꢁC8);
2100 (w), w(C1ꢁC2); 1492 (m), w(CꢂC aryl); 832 (s),
p-substitution. Anal. Calc. for C20H10 (250.30): C, 96.0;
H, 4.0. Found: C, 95.4; H, 3.6.
3
MHz): l 7.16 (s, 1H, C60H), 7.75 (d, J=8 Hz, 2H,
3
H5), 7.56 (d, J=8 Hz, 2H, H6), 0.33 (s, 9H, HCH ).
13C-NMR (CDCl3/CS2 (1:1), 75 MHz): [23] l 131.930/
131.78 (C5/C6), 123.76 (C7), 122.27 (C4), 104.44 (C8),
96.89 (C9), 93.97 (C2), 83.27 (C3), 61.67 (C1%), 54.99
(C1), −0.18 (CCH ); 151.20, 150.88, 147.46, 147.18,
3
146.47, 146.27, 146.24, 146.08, 145.64, 145.56, 145.44,
145.36, 145.30, 145.21, 144.55, 144.36, 143.07, 142.47,
142.45, 141.96, 141.91, 141.88, 141.71, 141.57, 141.49,
140.23, 135.91, 135.05 (28 signals, sp2 C on the C60
core). IR (KBr, cm−1): 2953 (w), 2920 (w), w(CꢀH
aryl); 2154 (w), w(CꢁCTMS); 1436 (w), 1428 (w), 1424
(w), 1418 (w), 1188 (w), 1176(w), 586 (w), 575 (w), 566
(w), 549 (w), 545 (w), 526 (s), C60 bands. MS (FAB+):
m/z 919 (M+), 720 (C60).
The syntheses of the acetylenic derivatives of C60,
[(trimethylsilyl)ethynyl]hydrofullerene[60]
(8a)
and
(phenylethynyl)hydrofullerene[60] (9), have been re-
ported using refluxing toluene [21]. However, the for-
mation of 1-octynylhydrofullerene[60] was more
recently carried out in THF [22], and this method was
preferred here as it allows for higher yields of the
monoacetylene derivatives of C60 and simplifies the
procedure. The new ligand [(trimethylsilyl)diethynyl-
benzene]hydrofullerene[60] (10a) was obtained similarly
by reacting lithiated p-(trimethylsilyl)diethynylbenzene
with C60 in THF as detailed below.
4.3. Syntheses of the complexes
The dicobalt hexacarbonyl complexes based on di-
ethynylbenzene and its dimers were obtained by the
standard methods of stirring the ligand and dicobaltoc-
tacarbonyl under argon for 1 h in hexane or
dichloromethane. In the case of the products resulting
from the coordination of {Co2(CO)6} to C60 acetylenes,
Scheme 4. Schematic representation of the synthesis of coupled ethynylbenzene.

164
S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
toluene was used as the solvent. The fullerene-based
ligands 8a, 9 and 10a were reacted with dicobaltoc-
tacarbonyl in toluene and isolated by flash chromatog-
raphy (SiO2, cyclohexane) to yield the correspon-
ding complexes [(trimethylsilyl)(dicobalthexacarbonyl)-
ethynyl]hydrofullerene[60] (11a), (phenylethynyl)(di-
cobalthexacarbonyl)hydrofullerene[60] (12) and [(tri-
methylsilyl)bis(dicobalthexacarbonyl)diethynylbenzene]
(13a).
Suitable elemental analyses could not be obtained for
all the metal complexes [23]. This was due to difficulties
in separating the pure product from unreacted ligand:
prolonged or repeated column chromatography results
in the degradation of the product to metal residues that
stick to the silica and free ligand that travels at the
same rate as the product. In these cases mass spectra
were obtained.
4.3.4. [{Co2(CO)6}2(v4-p2:2:2:2-Me3SiC2C6H4C2SiMe3)]
(3b)
A brown product, isolated by flash chromatography
(SiO2, hexane). TLC: Rf 0.3. Yield 29%. M.p.=103–
105°C. 1H-NMR (CDCl3, 400 MHz): l 7.47 (s, 4H,
H4), 0.45 (s, 18H, HCH ). 13C-NMR (CDCl3, 75 MHz):
3
l 199.91 (CCO), 138.15 (C3), 130.39 (C4), 104.28 (C2),
79.92 (C1), 0.95 (CCH ). IR (CsI) (cm−1): 2964 (w),
w(CꢀH aryl). IR (w(CO),3hexane) (cm−1): 2091 (w), 2086
(m), 2054 (s), 2027 (s), 2010 (w), 1979 (w). MS (FAB+):
m/z 839 [M+−3H]. Anal. Calc. for C28H22O12Si2Co4
(842.38): C, 39.9; H, 2.6; Co, 28.0. Found C, 40.1; H,
2.9; Co, 27.8.
4.3.5. [{Co2(CO)6}(v2-p2:2-Me3SiC2C6H4C2SiMe3)] (4b)
Isolated as a red solid yield via flash chromatography
(SiO2, hexane) TLC: Rf 0.3. Yield 22%. M.p.=112–
1
114°C. H-NMR (CDCl3, 300 MHz): l 7.45 (s, 4H),
4.3.1. [{Co2(CO)6}(v2-p2:2-HC2C6H4C2H)] (4)
0.42 (s, 9H, HCH ), 0.27 (s, 9H, HCH ). 13C-NMR
Isolated as a bright red product by flash chromatog-
raphy (Al2O3, hexane). TLC: Rf 0.5. Yield: 28%.
M.p.=78–80°C. 1H-NMR ((CD3)2CO, 300 MHz): l
3
3
(CDCl3, 75 MHz) l 199.74 (CCO), 138.82 (C6), 132.46
(C4), 129.65 (C5), 122.55 (C3), 104.78 (C2), 104.11 (C7),
95.76 (C1), 79.86 (C8), 0.82 (CCH ), −0.10 (CCH ). IR
3
3
7.63 (d, J=8 Hz, H5), 7.51 (d, J=8 Hz, H4) (4H),
6.89 (s, 1H, H8), 3.75 (s, H1). 13C-NMR ((CD3)2CO, 75
MHz): l 199.46 (CCO), 138.93 (C6), 132.86 (C4), 130.64
(C5), 122.38 (C3), 89.22 (C7), 83.56 (C2), 79.88 (C1),
73.97 (C8). IR (CsI) (cm−1): 3315 (s), w(HꢀCꢁ); 3118
(w), w(terminal HꢀC). IR (w(CO), hexane) (cm−1): 2096
(m), 2059 (s), 2034 (s), 2031 (s), 2018 (w), 1987 (w). MS
(FAB+): m/z 412 [M+].
3
3
(w(CO), hexane) (cm−1): 2089 (m), 2053 (s), 2027 (s),
2025 (s), 2011 (w), 1980 (w); 2160 (w), w(CꢁC); MS
(FAB+): m/z 557 [M+]. Anal. Calc. for
C22H22O6Si2Co2 (556.45): C, 47.5; H, 4.00; Co, 21.2.
Found C, 47.3; H, 4.00; Co, 21.0.
4.3.6. [{Co2(CO)6}4(v8-p2:2:2:2:2:2:2:2-Me3SiC2C6H4C2-
C2C6H4C2SiMe3)] (5b)
4.3.2. [{Co2(CO)6}2(v4-p2:2:2:2-Me3SiC2C6H4C2H)] (3a)
Flash chromatography (SiO2, hexane) isolated a red
brown fraction. TLC: Rf 0.3. Yield 19%. M.p.=128–
130°C. 1H-NMR ((CD3)2CO, 300 MHz): l 7.62 (d,
Isolated via flash chromatography (SiO2, hexane) as
a brown solid. TLC: Rf 0.6. Yield: 52%. M.p.\360°C.
(Al2O3, hexane). 1H-NMR (CDCl3, 300 MHz) l 7.47 (s,
8H, H4/H5), 0.43 (s, 18H, HCH3). 13C-NMR (CDCl3, 75
MHz): l 199.79 (CCO), 198.56 (CCO), 138.56/138.29
(C3/C6), 130.07/129.62 (C4/C5), 104.26 (C2), 99.41 (C8),
3
3J=8Hz)/7.59 (d, J=8 Hz) (4H, H4/H5), 6.84 (s, 1H,
H1), 0.42 (s, 9H, H CH3). 13C-NMR ((CD3)2CO, 75
MHz): l 200.41 (CCO), 200.07 (CCO), 138.20/138.71
(C6/C3), 131.29/130.86 (C4/C5), 105.04 (C7), 89.77 (C2),
93.47 (C7), 79.83 (C1), 1.00 (CCH ). IR (CsI) (cm−1):
3
2962 (w), 2925 (w), 2859 (w), w(CꢀH aryl); 1250 (m),),
w(SiꢀMe); IR (w(CO), hexane) (cm−1): 2101 (w), 2086
(m), 2083 (m), 2063 (s), 2053(s), 2038 (w), 2027 (s), 2011
(w), 1983 (w). MS (FAB+): m/z 1538 [M+].
80.50 (C8), 74.28 (C1), 0.62 (CCH ). IR (CsI) (cm−1):
3
2965 (w), w(HꢀC aryl); 3119 (w), w(terminal HꢀC). IR
(w(CO), hexane) (cm−1): 2096 (w), 2088 (m), 2060 (s),
2054 (m), 2028 (s), 2011 (w), 1983 (w). MS (FAB+):
m/z 698 [M+].
4.3.7. [{Co2(CO)6}4(v8-p2:2:2:2:2:2:2:2-HC2C6H4C2-
C2C6H4C2H)] (5)
Purified as a brown solid through flash chromatogra-
4.3.3. [{Co2(CO)6}(v2-p2:2-Me3SiC2C6H4C2H)] (4a)
Isolation of the product as a bright red solid via flash
chromatography (SiO2, hexane). TLC Rf 0.2. Yield
phy (Al2O3, hexane). TLC: Rf 0.5. Yield: 21%. M.p.\
1
1
3
35%. M.p.=77–79°C;. H-NMR (CDCl3, 400 MHz) l
360°C. H-NMR (CDCl3, 300 MHz): l 7.48 (d, J=8
3
3
3
7.47(d, J=8 Hz)/7.44 (d, J=8 Hz) (H4/H5, 4H), 6.38
Hz, 2H, H4/H5)/7.42 (d, J=8 Hz, 2H, H4/H5), 6.39 (s,
(s, 1H, H1), 0.28 (s, 9H, HCH ). 13C-NMR (CDCl3, 100
1H, H1). 13C-NMR (CDCl3, 75 MHz): l 199.20 (CCO),
198.58 (CCO), 138.64 (C6), 137.47 (C3), 130.38/129.69
(C4/C5), 98.85 (C8), 93.78 (C7), 88.87 (C2), 72.61 (C1).
IR (CsI) (cm−1): 2961 (m), 2924 (m), 2859 (w), w(CꢀH
aryl). IR (w(CO), hexane) (cm−1): 2102 (w), 2094 (m),
2083 (m), 2064 (s), 2032 (s), 2018 (w), 1985 (w). MS
(FAB+): m/z 1366 [M+−CO].
3
MHz) l 199.20 (CCO), 137.97 (C3), 132.41 (C5), 129.96
(C4), 122.80 (C6), 104.88 (C7), 95.76 (C8), 88.83 (C2),
72.59 (C1), −0.09 (CCH ). IR (CsI) (cm−1): 2962 (m),
3
w(CꢀH aryl); 2160 (m), w(CꢀCH). IR (w(CO), hexane)
(cm−1): 2095 (m), 2059 (s), 2033 (s), 2031 (s), 2018 (w),
1986 (w); 2160 (w), w(CꢁC). MS (FAB+) m/z 485 [M+].

S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
165
4.3.8. [{Co4(CO)8(v–CO)2}(v4-HC2C6H4C2H)] (6)
Dicobaltoctacarbonyl (0.410 g, 1.2 mmol) was heated
in hexane (70 ml) at 50°C for 3 h when TLC (SiO2,
hexane) indicated that all dicobaltoctacarbonyl had
transformed into tetracobaltdodecacarbonyl. The reac-
tion vessel was left to cool down. The solvent was
removed under vacuum to give a black solid and was
replaced with CH2Cl2 (40 ml). The dark brown solution
was added via cannula to a solution of diethynylben-
zene (0.076 g, 0.6 mmol) in CH2Cl2 (20 ml) and left
stirring at room temperature wrapped in tin foil under
argon flow. The solution was followed by TLC (SiO2,
hexane) and allowed to continue for 4 days before it
was considered complete. The solvent was removed
under vacuum and (tetracobalt)decacarbonyl was re-
covered as a blue solid. TLC: Rf 0.1 (SiO2, hexane).
146.27, 147.11, 147.37, 152.13, 154.71. IR (KBr, cm−1):
2963(m), 2911(w), 2848 (w), 2088s, 2051 (s), 2025 (s),
2019 (s), 1261 (vs), 1183 (w) (C60), 1098 (vs), 1022 (vs)
801 (s), 576 (w) (C60), 526 (m) (C60). IR (w(CO), hexane,
cm−1): 2092 (w), 2056 (s), 2032 (s), 2026 (s).
4.3.11. 1-hydro-9-[(dicobalthexacarbonyl)phenyl-
acetylene]fullerene[60] (12)
Purified by flash chromatography (SiO2, cyclohexane)
to give a red–brown powder. TLC: Rf 0.3. Yield: 71%.
1
M.p.\360°C. H-NMR (CDCl3/CS2 (1:1), 400 MHz):
l 6.75 (s, C60H), 8.12 (m, H5), 7.56 (m, H6/H7). 13C-
NMR (CDCl3/CS2 (1:1), 100 MHz): l 198.90 (CCO),
137.59 (C4), 129.81/129.36 (C5/C6), 128.48 (C7), 108.21
(C2), 93.05 (C3), 65.80 (C1), 62.88 (C1%); 154.77, 152.58,
147.63, 147.38, 146.44, 146.47, 146.28, 146.22, 145.92,
145.70, 145.50, 145.43, 144.76, 144.52, 143.22, 142.71,
142.66, 142.35, 142.18, 142.08, 141.90, 141.80, 141.71,
140.36, 140.30, 136.04, 135.17 (27 signals due to the sp2
carbon atoms on in the C60 core). IR (KBr, cm−1):
2960 (w), 2921 (w), 2850 (w), w(CꢀH aryl); 1436 (w),
1429 (w), 1424 (w), 1189 (w), 1182 (w), 1176 (w), 578
(w), 574 (w), 526 (s), 518 (m), 512 (m), C60 bands. IR
(w(CO), cyclohexane, cm−1): 2094 (m), 2058 (s), 2036 (s),
2028 (s), 2016 (w), 1983 (w). Anal. Calc. for
C74H6O6Co2 (1108.7): C, 80.2; H, 0.5. Found C, 79.7;
H, 1.0.
1
Yield 48%. H-NMR (CDCl3, 300 MHz): l 8.43 (s, 1H,
H1), 7.33 (d, 3J=8 Hz, 2H, H5), 7.07 (d, 3J=8 Hz, 2H,
H4), 3.14 (s, H8). 13C-NMR (CDCl3, 75 MHz): l 151.83
(C3), 131.87 (C5), 125.74 (C4), 122.35 (C6), 82.76 (C7),
78.70 (C8). IR (w(CO), Nujol, cm−1): 2091 (w), 2053 (s),
2040 (s), 2020 (w, sh), 1996 (w), 1980 (w, sh), (terminal
CO); 1879 (w), 1858 (w), (bridging CO); MS (FAB+):
m/z 643 [M+].
4.3.9. [{Co2(CO)6}{(Co4(CO)8(v–CO)2}(v6–HC2-
C6H4C2H)] (7)
Tetracobaltdodecacarbonyl was prepared as above
from dicobaltoctacarbonyl (0.067 g, 0.2 mmol) and was
reacted with dicobalthexacarbonyl diethynylbenzene
(0.041 g, 0.1 mmol) in CH2Cl2 (40 ml). The mixture was
allowed to stir under argon flow and wrapped in tin foil
for 3 days. Flash chromatography (SiO2, hexane) was
performed under argon with dry and degassed hexane,
and isolated (tetracobaltdecacarbonyl)(dicobalthexa-
carbonyl)diethynylbenzene as a dark blue solid. TLC:
Rf 0.1 Yield: 0.061 g, 66%. 1H-NMR (CDCl3, 300
4.3.12. 1-hydro-9-[bis(dicobalthexacarbonyl)(trimethyl-
silyl)diethynylbenzene)]fullerene[60] (13a)
Purified as a red–brown solid via flash chromatogra-
phy (SiO2, cyclohexane). TLC: Rf 0.2. Yield: 65%.
1
M.p.\360°C. H-NMR (CDCl3/CS2 (1:1), 400 MHz):
3
3
l 6.78 (s, C60H), 8.07 (d, J=8 Hz, H5), 7.66 (d, J=8
Hz, H6), 0.42 (s, 18H, HCH ). 13C-NMR (CDCl3/CS2
3
(1:1), 100 MHz) l 199.56 (CCO), 198 73 (CCO), 139.05
(C4), 137.48 (C7), 130.26/130.66 (C5/C6), 108.46 (C2),
103.72 (C8), 91.77 (C3), 80.00 (C9), 65.54 (C1), 62.93
3
MHz) l 8.42 (s, 1H, H1), 7.34 (d, J=8 Hz, 2H, H5),
3
7.06 (d, J=8 Hz, 2H, H4), 6.37 (s, 1H, H8). 13C-NMR
(C1%), 0.92 (CCH ); 154.55, 152.39, 147.58, 147.33,
3
(CDCl3, 75 MHz) l 199.11 (CCO, {Co2(CO)6}), 151.33
(C3), 138.31 (C6), 129.71 (C5), 126.24 (C4), 88.28 (C7),
72.75 (C8). IR (w(CO), Nujol, cm−1) 2093 (w), 2090 (w),
2058 (s), 2032 (s), 2016 (w, sh), 1996 (w), 1980 (w, sh),
(terminal CO); 1879 (w), 1865 (w), (bridging CO); MS
(FAB+): m/z 927 [M+].
146.43, 146.39, 146.23, 146.18, 145.78, 145.67, 145.63,
145.48, 145.46, 145.37, 144.71, 144.46, 143.16, 142.68,
142.61, 142.31, 142.16, 142.03, 141.85, 141.75, 141.67,
140.31, 140.29, 135.95, 135.13 (29 signals due to sp2
carbons on the C60 core). IR (CsI) (cm−1): 2961 (w),
2925 (m), 2851 (w), w(CꢀH aryl); 1437 (w), 1430 (w),
1425 (w), 1419 (w), 580 (w), 574 (w), 526 (w), 514 (m),
C60 bands. IR (w(CO), cyclohexane, cm−1): 2094 (m),
2088 (m), 2060 (s), 2052 (s), 2036 (m), 2028 (s), 2010
(w), 1988 (w). Anal. Calc. for C85H14O12SiCo4 (1490.9):
C, 68.5; H, 0.9. Found C, 69.0; H, 1.4.
4.3.10. HC60[C2{Co2(CO)6}]SiMe3 (11a)
Purified by column chromatography (SiO2, loaded
with CS2 and eluted with hexane) to give a black
1
powder. TLC: Rf 0.4. Yield 80%. H-NMR (300 MHz,
CS2/CDCl3) l 6.74 (s, 1H), 0.59 (s, 9H). 13C-NMR
(75.47MHz, CS2/CDCl3) d 79.2 (C1), 80.5 (C2), 1.2 (C3),
67.5 (C4), 64.0 (C5), 199.4 (CCO), C60 core: l134.91,
135.85, 140.05, 140.16, 141.54, 141.71, 141.85, 141.99,
142.16, 142.46, 142.5, 142.83, 142.99, 144.29, 144.56,
145. 19, 145.27, 145.32, 145.44, 146.0, 146.03, 146.21,
4.3.13. [HC2{Co2(CO)6}]2C6H2Br (16)
Red compound, isolated by flash chromatography
(SiO2/hexane). TLC: Rf 0.4. Yield 92%. M.p. 101–
1
102°C (dec.). H-NMR (400 MHz, CDCl3): l 6.36(s,
2H), 7.55 (s, 2H), 7.60 (s, 1H). 13C (100 MHz, CDCl3):

166
S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
Table 2
Crystallographic data for 3a, 3b, 4, 4b, 16 and 15 a
3a
3b
4
4b
16
15
Molecular formula
C25H14Co4O12Si C28H22Co4O12Si2 C16H6Co2O6
C22H22Co2O6Si2 C22H5BrCo4O12 C30H6Co6O18
Crystal dimensions (mm)
Colour
Habit
0.5×0.2×0.4
Red
Prism
0.4×0.5×0.4
Brown
Prism
0.7×0.5×0.5
Bright-red
Prism
0.3×0.4×0.4
Red
Prism
0.1×0.3×0.5
Red
Plate
0.05×0.2×0.5
Deep-red
Plate
Crystal system
Triclinic
8.655(3)
12.840(4)
14.242(5)
92.700(2)
95.375(3)
99.067(5)
1552.9(9)
Triclinic
8.3652(8)
8.7213(8)
12.765(1)
79.694(7)
87.358(6)
73.839(8)
880.0(2)
Triclinic
7.776(3)
7.772(2)
14.277(3)
101.00(1)
90.32(2)
97.96(2)
838.4(4)
Triclinic
8.953(2)
11.807(3)
12.950(2)
90.65(2)
98.69(1)
96.28(2)
1344.5(5)
Monoclinic
12.747(3)
7.958(1)
27.509(6)
90
101.433(9)
90
2735.3(9)
P21/n
Orthorhombic
13.204(3)
42.53(2)
13.428(6)
90
90
90
7451(5)
Pmna
8
,
a (A)
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
(
(
(
(
Space group
Z
p1
p1
p1
P1
2
1
2
2
4
Theta range (°)
1.44–24.99
1.647
1.62–24.97
1.589
1.45–24.95
1.632
1.59–24.97
1.374
1.51–24.97
1.887
1.44–20.00
1.839
Dcalc. (g cm−3
)
F000
764
2.194
5636
5263
0.0197
0.0477
0.1110
1.105
422
1.976
3232
3012
0.0088
0.0314
0.0793
1.213
408
2.005
2175
1948
0.0123
0.0334
0.0802
1.245
568
1.354
5053
4722
0.0168
0.0411
0.1022
1.122
1504
3.902
4578
4481
0.0257
0.0496
v(MoꢀKa) (cm−1
)
Total no. of reflections
Independent reflections
Rint
b
R1
b
wR2
Goodness of fit
0.0789
Largest diff. peak and hole
1.208 −0.502
0.673 −0.339
0.761 −0.381
0.762 −0.285
0.584 −0.548
−3
,
(e A
)
a For solution, refinement procedures and treatment of hydrogen atoms see Section 5.
b For I\2|(I).
l 72.5 (C1) 87.1 (C2) 122.6 (C5) 131.3 (C4) 140.8 (C3)
198.8 (C6, broad). IR (w(CO), hexane, cm−1) 2096 (s),
2064 (s), 2033 (s). Anal. Calc. for C22H5BrO12Co4
(776.9): C, 34.0; H, 0.6. Found C, 34.0; H, 0.5.
were used in structure solution and refinement. The
structures were solved by automatic direct methods
using SHELXS-86 [24] and refined by full-matrix least-
squares analysis on F2 with SHELXL [25]. Final elec-
tron density difference maps showed no regions of
significant electron density. All non-hydrogen atoms
were refined with anisotropic displacement parameters.
The hydrogen atoms were treated differently in each
case. All the hydrogen atoms of 16, the benzene pro-
tons of 3b, and the terminal ‘acetylenic’ protons of 4
and 3a were located from subsequent Fourier differ-
ence maps and refined isotropically with individual
temperature factors. The remaining hydrogen atoms of
these structures and all those of 4b were placed in
calculated positions riding on the appropriate carbon
atom. The ORTEP diagrams were presented using OR-
TEX [26].
4.3.14. [HC2{Co2(CO)6}]3C6H3 (15)
Red product, isolated by flash chromatography
(SiO2/hexane). TLC: Rf 0.32. Yield 93%. M.p. 100–
1
102°C (dec.). H-NMR (300 MHz, CDCl3) l 6.40 (s,
3H), 7.55 (s, 3H). 13C-NMR (75 MHz, CDCl3): l
130.7 (C4) 139.3 (C3)72.8 (C1) 88.4 (C2) 199.1 (C5,
broad). IR (w(CO), hexane, cm−1) 2093 (s), 2064 (s),
2031 (s). Calc. for C30H6O18Co6 (1007.97): C, 35.7; H,
0.6. Found C, 36.0; H, 1.0.
5. X-ray structure determination
The crude crystallographic data obtained for 15 re-
sulted only in the location and refinement of the core
atoms. The crystal and cell dimensions were not suit-
able for the diffractometer or the source available. The
core atoms were refined anisotropically. For the
molecular representation, the graphics programme
SCHAKAL 93 was used [27].
The crystal structure data were collected on an En-
raf–Nonius CAD-4 diffractometer. The crystal data
and experimental parameters are summarised in Table
2. No decay or absorption corrections were applied to
the data collected. The data were reduced to give the
number of unique reflections and those with F]ꢀ4|ꢀF

S.M. Draper et al. / Journal of Organometallic Chemistry 589 (1999) 157–167
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6. Supplementary material
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 124699, 124700, 124701,
124702 and 124703 for compounds 3a, 3b, 4, 4b, 16.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12, Union Road,
Cambridge CB2 1EZ (Fax: +44-1223-336-033; email:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.-
cam.ac.uk).
[14] B.F.G. Johnson, J. Lewis, P.R. Raithby, D.A. Wilkinson, J.
Organomet. Chem. 408 (1991) C9.
Acknowledgements
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D.J. Willams, P. Zanell, Organometallics 16 (1997) 2646. (b) I.R.
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The authors thank FORBAIRT (Enterprise Ireland)
for financial support (grant SC/96/425) and the Trinity
Trust for a scholarship to M.D.
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