Syntheses and molecular structures of some compounds containing many-atom chains end-capped by tricobalt carbonyl clusters

Article abstract of DOI:10.1016/j.jorganchem.2008.06.007

Several complexes containing Co₃ carbonyl clusters end-capping carbon chains of various lengths are described. Pd(0)/Cu(I)-catalysed reactions between {Co₃{μ₃-C(C{triple bond, long}C)₂Au(PPh₃)}(μ-dppm)(CO)₇ and I(C{triple bond, long}C)₂SiMe₃ or FcC{triple bond, long}CI gave {Co₃{μ₃-C(C{triple bond, long}C)_xR}(μ-dppm)(CO)₇ [x = 4, R = SiMe₃ 3; x = 3, R = Fc 8]; treatment of 3 with NaOMe and AuCl(PPh₃) gave 4 [x = 4, R = Au(PPh₃)]. Related preparations of Co₃{μ₃-C(C{triple bond, long}C)₂[Ru(PP)Cp′]}(μ-dppm)_n(CO)_9-2n [PP = (PPh₃)₂, Cp' = Cp, n = 1, 5; PP = dppe, Cp′ = Cp^*, n = 1, 6; 0, 7] are also described. Syntheses of bis-cluster complexes {Co₃(μ-dppm)(CO)₇}₂(μ-C_x) (x = 14, 12; 16, 9; 18, 11; 26, 10) - the latter being the longest cluster-capped C_x chains so far described - and the mercury-bridged compounds Hg{(C{triple bond, long}C)_xC[Co₃(μ-dppm)(CO)₇]}₂ (x = 1, 13; 2, 14) are reported. The molecular structures of 7, 12, 13 and 14, as well as of Co₃(μ₃-CC{triple bond, long}CSiMe₃)(μ-dppm)(CO)₆(PPh₃) (15) and Co₃{μ₃-CC(O)OEt}(μ-dppm)(CO)₇ (16), are reported.

Full text of DOI:10.1016/j.jorganchem.2008.06.007

Journal of Organometallic Chemistry 693 (2008) 2887–2897
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Syntheses and molecular structures of some compounds containing many-atom
chains end-capped by tricobalt carbonyl clusters
a
b
c
c
Michael I. Bruce a, , Natasha N. Zaitseva , Brian K. Nicholson , Brian W. Skelton , Allan H. White
*
a School of Chemistry and Physics, University of Adelaide, Adelaide, South Australia 5005, Australia
b Department of Chemistry, University of Waikato, Hamilton, New Zealand
c Chemistry M313, SBBCS, University of Western Australia, Crawley, Western Australia 6009, Australia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 7 May 2008
Received in revised form 4 June 2008
Accepted 4 June 2008
Available online 10 June 2008
Several complexes containing Co3 carbonyl clusters end-capping carbon chains of various lengths are
described. Pd(0)/Cu(I)-catalysed reactions between {Co3{ 3-C(C„C)2Au(PPh3)}( -dppm)(CO)7 and
I(C„C)2SiMe3 or FcC„CI gave {Co3{ 3-C(C„C)xR}( -dppm)(CO)7 [x = 4, R = SiMe3 3; x = 3, R = Fc 8]; treat-
ment of 3 with NaOMe and AuCl(PPh3) gave 4 [x = 4, R = Au(PPh3)]. Related preparations of Co3{l3
C(C„C)2[Ru(PP)Cp0]}( -dppm)n(CO)9ꢀ2n [PP = (PPh3)2, Cp’ = Cp, n = 1, 5; PP = dppe, Cp0 = Cp*, n = 1, 6; 0,
7] are also described. Syntheses of bis-cluster complexes {Co3( -dppm)(CO)7}2( -Cx) (x = 14, 12; 16, 9;
18, 11; 26, 10) – the latter being the longest cluster-capped Cx chains so far described – and the mer-
cury-bridged compounds Hg{(C„C)xC[Co3( -dppm)(CO)7]}2 (x = 1, 13; 2, 14) are reported. The molecular
structures of 7, 12, 13 and 14, as well as of Co3( 3-CC„CSiMe3)( -dppm)(CO)6(PPh3) (15) and Co3{l3
CC(O)OEt}( -dppm)(CO)7 (16), are reported.
l
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Keywords:
Cobalt cluster
XRD structure
Carbon chains
Mercury
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Ó 2008 Elsevier B.V. All rights reserved.
Gold
Ruthenium
1. Introduction
described complexes containing C12 chains linking Fe(CO)2Cp* [5],
trans-RuCl(dppe)2 [6] and Ru2(ap)4 (ap = 2-anilinopyridinate) [7]
fragments. A variety of other end-groups have been linked via reac-
tions involving a phosphine–gold(I) halide elimination reaction,
which has some relation to the well-known Sonogashira reaction.
Molecules containing chains of C(sp) atoms are of contempo-
rary interest as models for molecular wires, as well as for their po-
tential as sources of highly unsaturated derivatives [1]. Although
the redox properties of complexes containing such chains end-
capped by mononuclear and binuclear metal–ligand fragments
have received the most attention, an important sub-group consists
of those compounds containing the carbon chain capped by metal
cluster moieties. Predominant among these is the tricobalt car-
bonyl cluster by virtue of its tendency to interact in
the terminal carbon atom. Much of the chemistry of tricobalt–car-
bon clusters Co3( 3-CR)(CO)9 with a large variety of substituents R,
which have been known since the 1960s, has been summarised in
several reviews [2].
A
preliminary report describing the compounds {Ru(dp-
pe)Cp*}2(
-C14) and {Co3( -dppm)(CO)7}2( -C16) has been pub-
lished [8].
l
l
l
In the course of our work on molecules of this type, we have pre-
pared and characterised (including XRD structures) several unusual
examples, together with relevant intermediates and side-products.
These results are collected in this paper, which describes the com-
l3 mode with
l
plexes Co3{
PP = dppe, Cp0 = Cp*; n = 1, PP = (PPh3)2, Cp0 = Cp], containing C5
chains end-capped by different metal centres, and Co3{l3
C(C„C)3Fc}( -dppm)(CO)7 in which the redox centres are
separated by seven carbon atoms. The complexes {Co3(
dppm)(CO)7}2( -Cx) (x = 14, 16, 18, 26) contain the longest Cx
l l-dppm)n(CO)9ꢀ2n [n = 0, 1,
3-C(C„C)2[Ru(PP)Cp0]}(
-
While the majority of complexes in which redox centres are
connected by chains of carbon (or other) atoms have eight or fewer
atoms in the chain, there is an increasing number of reports
describing compounds with longer chains. Thus, Gladysz’s pioneer-
ing studies of rhenium- and platinum-containing systems has so
l
l-
l
chains end-capped by Co3 clusters yet described. We have also uti-
lised coupling of carbon chains through mercury atoms, the well-
established linear geometry of the Hg(II) atom providing a facile
means of doubling the chain length of the precursors by incorpora-
tion of the heteroatom in the centre. The compounds
far culminated in the complexes {Re(NO)(PPh3)Cp*}2(
and {trans-Pt(C6F5)[P(tol)3]2}2( -C28) [4], elegant synthetic strate-
gies being developed to access the longer chains. Others have
l-C20) [3]
l
Hg{(C„C)xC[Co3(
way. In addition, details of the preparations of the related materi-
als, Co3{ 3-C(C„C)xR}( -dppm)(CO)7 [x = 2, 4, R = SiMe3; x = 4,
l-dppm)(CO)7]}2 (x = 1, 2) were made in this
* Corresponding author. Fax: +61 8 8303 4358.
E-mail address: michael.bruce@adelaide.edu.au (M.I. Bruce).
l
l
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.06.007

2888
M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
R = Au(PPh3)] and the molecular structures of the by-products
Co3( 3-CR)( -dppm)(CO)6(L) (R = CC„CSiMe3, L = PPh3; R = CO2Et,
L = CO) are given.
The complexes were characterised by microanalyses and from
their spectroscopic properties, including weak (C„C) bands be-
tween 2113 and 2156 cmꢀ1 and terminal
(CO) band patterns be-
l
l
m
m
tween 2067 and 1972 cmꢀ1. In their NMR spectra, the SiMe3
group resonates at dH 0.30, dC ꢀ0.27, with the two dppm CH2 pro-
ton multiplets centred at dH 3.45, 4.30; the CH2 carbon gives a trip-
let at dC 43.8. In the 13C NMR spectrum of 3 eight singlets between
dC 63.59 and 98.76 arise from eight of the nine carbon chain nuclei,
that attached to the Co3 cluster being broadened past visibility by
the 59Co quadrupole [11,12]. Resonances in the 31P NMR spectra at
dP ca. 34 and 41 are assigned to dppm and PPh3 (if present). The
electrospray mass spectra (ES-MS) contain ions [MꢀSiMe3]ꢀ or
M+, respectively.
2. Results and discussion
We have found that useful precursors for complexes containing
extended carbon chains are the monometallic complexes in which
the other end of the chain bears a SiMe3 group. Complexes Co3{l3
C(C„C)xSiMe3}( -dppm)(CO)7 (x = 1, 1; 2, 2) have been previously
reported, having been obtained by reactions between Co3(l3
CBr)( -dppm)(CO)7 and Au{(C„C)xSiMe3}(PR3) (R = Ph or tol) [9].
-
l
-
l
These are examples of the Pd(0)/Cu(I)-catalysed phosphine–gold(I)
elimination reaction between alkynyl-gold(I) complexes and C(sp
or sp2)–X (X = Br, I) groups described earlier as a general base-free
route to many transition metal complexes containing alkynyl and
poly-ynyl groups [8]. Preparation of the Au(PPh3) precursors is
readily achieved by reaction of the corresponding SiMe3 deriva-
tives with AuCl(PPh3) in the presence of NaOMe.
We have used Pd(0)/Cu(I)-catalysed coupling reactions [8] be-
tween Co3(
(PP)Cp0 to prepare Co3{
[PP = (PPh3)2, Cp0 = Cp 5; PP = dppe, Cp0 = Cp* 6] in 77% and 69%
l
3-CBr)(
l
-dppm)(CO)7 and Ru{C„CC„CAu[P(tol)3]}-
l
3-C(C„C)2[Ru(PP)Cp0]}(
l-dppm)(CO)7
yields, respectively (Scheme 2). The related complex Co3{l3
-
C(C„C)2[Ru(dppe)Cp*]}(CO)9 (7) was obtained similarly in 40%
yield. These compounds formed orange to brown crystals, which
were identified by microanalyses and spectroscopy. The IR spectra
In seeking to extend the carbon chain lengths in these com-
pounds, we have now prepared dark brown-red {Co3{l3
C(C„C)4SiMe3}( -dppm)(CO)7 (3) in 68% yield from the Pd(0)/
Cu(I)-catalysed reaction between {Co3{ 3-C(C„C)2Au(PPh3)}(
dppm)(CO)7 [8b] and IC„CC„CSiMe3 [10]. Conversion to the
Au(PPh3) derivative as described above gave brown {Co3{l3
C(C„C)4Au(PPh3)}( -dppm)(CO)7 (4) in 76% yield (Scheme 1).
-
contain weak
(CO) bands between 2063 and 1952 cmꢀ1 for 5 and 6, these bands
moving to higher energy for (CC) 2124, (CO) 2094–
m
(C„C) bands at ca 2107 or 2124 cmꢀ1 and terminal
l
m
l
l-
7
[m
m
1976 cmꢀ1]. In the NMR spectra, resonances for Ru–Cp0 [dH 4.45,
dC 87.18 (Cp in 5), dH 1.59 [1.59], dC 10.13, 93.64 [10.38, 94.93]
(Cp* in 6 [7])], CH2 from dppm and dppe (dH 1.92, 2.24, dC 29.94)
and Ph groups (dH 7.03–7.67, dC 130.21–138.40) are present. The
Co–CO groups give rise to resonances at dC ca 201, while three or
four carbon chain resonances are found as singlets between dC
86.0 and 138.35. As found earlier, the resonance of the carbon at-
-
l
(CO)
Co
3
(OC) Co
C
C
C
C
C
C
C
Fc
2
Ph P
2
(CO)
Co
3
Co(CO)
2
8
P
Ph
2
Fc
C
C
I
(OC) Co
2
C
Br
Pd(0) / Cu(I)
L
(CO)
Co
3
Co(CO)
2
L
(OC) Co
C
C
C
C
C
Au(PPh )
3
2
Ph P
2
Co(CO)
2
{(tol) P}Au
3
C
C
C
C
Ru(PP)Cp'
P
Ph
Pd(0) / Cu (I)
2
I
C
C
C
C
C
SiMe
3
Pd(0) / Cu(I)
(CO)
Co
3
R
(CO)
Co
5
3
(OC) Co
2
C
C
C
C
C
Ru
(OC) Co
2
C
C
C
C
C
C
C
C
X
P
Ph P
2
L
P
Co(CO)
2
Co(CO)
2
P
Ph
L
2
PP
X = SiMe
3
LL
R
3
AuCl(PPh ) /
3
NaOMe
5
6
7
dppm
dppm
(CO)
(PPh )
3
dppe
dppe
H
Me
Me
2
X = Au(PPh ) 4
3
2
Scheme 1.
Scheme 2.

M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
2889
tached to the Co3 cluster is not obvious, probably because of broad-
ening by the 59Co quadrupole. The 31P NMR spectra variously con-
tain resonances at dP ca. 33.5 (dppm), 49.4 (PPh3) and 79.45 (dppe).
In the ES-MS, either M+, [M+Na]+ or [M+OMe]ꢀ are present in spec-
tra obtained from solutions in MeOH containing NaOMe.
which unfortunately proved to be unsuitable for an XRD structure
determination. Characterisation rests upon the ES-MS, which con-
tains [M+Na]+ and [M+OMe]ꢀ at m/z 1849 and 1857, respectively.
The IR spectrum contains two very weak m(C„C) bands at 2168
and 2129 cmꢀ1, while the 1H and 31P NMR spectra show reso-
nances for dppm at dH 3.50, 4.24 (CH2) and 7.31–7.62 (Ph) and dP
34.0. Lack of solubility and a tendency to decompose in solution
have precluded our obtaining a 13C NMR spectrum.
The deep red C7 complex Co3{
could be obtained from the Pd(0)/Cu(I)-catalysed reaction between
FcC„CI [13] and Co3{ 3-C(C„C)2Au(PPh3)}( -dppm)(CO)7, carried
out in thf (Scheme 1). Spectroscopic properties of 8 include weak
(C„C) bands at 2168 and 2100 cmꢀ1 and terminal
(CO) absorp-
l3-C(C„C)3Fc}(l-dppm)(CO)7 (8)
l
l
The second product is dark red {Co3(l-dppm)(CO)7}2(l-C18)
m
m
(11), apparently formed by oxidative coupling of the gold-contain-
ing precursor 4. In this case, microanalytical and ES-MS data
([M+Na]+ and [MꢀH]ꢀ at m/z 1753 and 1729, respectively) support
tions between 2063 and 1958 cmꢀ1. In the NMR spectra, reso-
nances at dH 4.28, dC 70.35 (FeCp), dH 4.30, 4.56, dC 69.76, 72.35
[Fe(C5H4)], dH 3.40, 4.25, dC 42.75 (PCH2) and dH 7.15–7.69 (Ph)
are accompanied by signals between dC 63.38 and 99.03 (Cipso
and six of seven carbon chain nuclei). The expected [M+H]+ or
[MꢀH]ꢀ ion clusters are present in the positive and negative ion
ES-MS of 8.
the formulation. The IR spectrum contains two m(C„C) and five
terminal
dH 3.46, 4.24 (CH2), 7.27–7.71 (Ph) and dP 34.1.
On one occasion, we isolated a small amount of crystalline
material from the reaction between 4 and Ru3( -H)3( 3-CBr)(CO)9
m(CO) bands, while the dppm ligand gives resonances at
l
l
In seeking to prepare long, symmetrical Co3 cluster-capped car-
bon chains, we have applied the coupling reactions used so suc-
cessfully above and elsewhere [8] to Co3 clusters containing
Au(PPh3)-capped chains and diiodopoly-ynes (Scheme 3). In this
which, on the basis of the low-precision XRD structural determina-
tion reported here and an ES-MS (M+ at m/z 1682), was identified
as {Co3(l-dppm)(CO)7}2(l-C14) (12). However, we did not obtain
enough for microanalysis nor for any further characterisation.
It occurred to us that a further facile route to complexes con-
taining many-atom chains is the coupling reaction between Au-
or Hg and terminal alkynes. We and others have already reported
on the reactions of [ppn][Au(acac)2] with H(C„C)xR to give
[ppn][Au{(C„C)xR}2] [15,16], while similar linking of alkynyl
groups by attachment to the isoelectronic Hg(II) centre is also well
established [17]. In the present study, cobalt clusters containing
carbon chains linked through a mercury atom have been made
by treatment of 2 equiv. of the SiMe3 derivative with Hg(OAc)2 in
the presence of an excess of NaOMe at r.t. Reactions were moni-
tored by spot tlc and were usually complete within 2 h. Work-up
by preparative tlc then afforded the pure complexes. In this way,
way, the Pd(0)/Cu(I)-catalysed reactions between Co3{l3
C(C„C)2Au(PPh3)}( -dppm)(CO)7 and I(C„C)3I [10,14] afforded
dark red {Co3( -dppm)(CO)7}2( -C16) (9) in 86% yield. This com-
-
l
l
l
plex was characterised by a single-crystal XRD structure determi-
nation (see below), its spectroscopic properties being similar to
other complexes containing this Co3 cluster described above. Only
three very weak m
(C„C) bands, between 2171 and 2127 cmꢀ1, are
present in the IR spectrum. In the 13C NMR spectrum, seven sing-
lets between dC 64.36 and 99.83 arise from 14 of the C16 chain car-
bons, the CCo3 nucleus being broadened by the 59Co quadrupole. In
the positive ion ES-MS, [M+Na]+ appears at m/z 1729, while
[MꢀH]ꢀ (m/z 1705) is present in the negative ion spectrum. The
latter also contained [Co3(C8)(dppm)ꢀH]ꢀ as a strong fragment
ion at m/z 852.
we have prepared Hg{(C„C)xC[Co3(
14) in 13 and 74% yields, respectively, from Co3{l3
C(C„C)xSiMe3}( -dppm)(CO)7 (Scheme 4).
The IR spectra of 13 and 14 contain (CO) bands between 2060
and 1948 cmꢀ1 and weak absorptions assigned to
m(C„C) between
l-dppm)(CO)7]}2 (x = 1, 13; 2,
-
From the analogous reaction between Co3{
l3-C(C„C)4
l
Au(PPh3)}( -dppm)(CO)7 (4) and I(C„C)4I [10,14], we obtained
l
m
two products which were easily separated by preparative tlc. The
faster moving was found to be the expected coupling product
{Co3(l-dppm)(CO)7}2(l-C26) (10), obtained as dark purple crystals,
2135 and 2112 cmꢀ1. Not surprisingly, the 1H NMR spectra are
similar for both complexes: the dppm ligand gives multiplet reso-
(CO)
3
Co
(CO)
Co
3
(OC) Co
C
C
C
C
C
C
C
C
C
X
2
(OC) Co
C
(C
C) SiMe
x 3
2
Ph P
2
Co(CO)
2
Ph P
2
Co(CO)
2
P
Ph
2
P
Ph
2
I
(C C)
I
n
Hg(OAc)
NaOMe
Pd(0) / Cu(I)
2
(CO)
(CO)
Co
3
3
Co
(CO)
Co
(CO)
3
3
Co
(OC) Co
C
(C
C)
x
C
Co(CO)
2
2
Ph P
2
PPh
2
(OC) Co
C
2
(C
C)
x
Hg (C C)
C
Co(CO)
2
2
x
Co(CO)
(OC) Co
2
2
Ph P
2
PPh
2
P
P
Co(CO)
(OC) Co
2
Ph
Ph
2
2
P
P
Ph
Ph
2
2
9 x = 8 (n = 3); 10 x = 13(n = 4); 11 x = 9; 12 x = 7
x = 1 13; 2 14
Scheme 3.
Scheme 4.

2890
M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
nances between d 3.66 and 4.60, while the Ph protons give multi-
plets between d 7.18 and 7.56. Broad resonances for the dppm li-
gands are found at dP 34.6 and 35.0 in the 31P NMR spectra.
Positive and negative ion ES-MS contain [M+Na]+ and [MꢀH]ꢀ,
respectively, when NaOMe is present.
ters [19]. For the mercury complexes, irreversible oxidation waves
are also found at E2 = +0.94 and +0.89 V, respectively.
3. Molecular structures
During work-up, products of homo-coupling of the initial SiMe3
derivatives, i.e., {Co3(l-dppm)(CO)7}2(l-C2x+2) (x = 3, 4) were also
Figs. 1–6 are projections of single molecules of 7 and 12–16, se-
lected structural parameters being collected in Table 1. With the
isolated [9]. Although both 13 and 14 are stable in air in the solid
form, they have a tendency to lose mercury to give the same homo-
coupled products, so that it is unclear at what stage the mercury-
free products form. Elimination of mercury becomes easier as the
chain length increases and is found especially when solutions in
chlorinated solvents are left to stand for some time (hours) and
also upon heating. Heating 14 in refluxing thf for 1 h gave the
exception of 7, the common feature is the Co3(l3-C)(l-dppm) car-
bonyl cluster, for which the Co–Co [2.445(4)–2.497(1) Å], Co–P
[2.154(6)–2.2155(6) Å] and Co(1,2)–C [1.881(1)–1.924(2) Å] and
longer Co(3)–C separations [1.92(2)–1.943(7) Å] are similar to
those found in many other related structures [8,18,20–24]. The
dppm ligand takes up the chair conformation in all molecules,
again being similar to most previously described systems.
Of most interest in the present context are the carbon chains,
which show the usual short-long alternation of C–C bonds,
although the actual distances suggest that there is a small degree
of delocalisation along the chain. For example, in the two Hg-
bridged complexes, the separations are 1.220(8), 1.397(7) Å (for
13) and 1.245(11), 1.364(10), 1.231(10), 1.383(10) Å (14); the
Hg–C bonds are 1.973(5) and 1.985(6) Å, respectively, values
which may be compared with those found in Hg(C„CR)2
[2.00(2) Å (R = Ph, SiMe3) [26], 1.994(9) Å (R = C„CC(NMe2)@{W-
(CO)5}) [27]], for example. The chains are not strictly linear, with
angles at individual carbon atoms ranging between 172.7(5)° and
178.4(8)°. In 7, the C–C separations from C(5) (attached to Ru)
are 1.236(4), 1.350(4), 1.231(4) and 1.367(4) Å, with angles at the
carbon atoms between 174.0(3)° and 178.4(3)°. Total bending at
the C atoms amounts to 9.3° (for 13) and 6.1° (14); the molecules
are centrosymmetric, so that the C–Hg–C angles are necessarily
180°. This contrasts with the situation found for {[Cp*(dppe)R-
u]C„CC„C}2Hg, where the C–Hg–C angle is 166.5(3)°, likely the
result of steric interactions within the crystal [28].
C10 derivative [9] in 27% yield. Similar extrusion of the heteroatom
occurs easily with cis-Pt{C5Co3(l-dppm)(CO)7}2(PEt3)2, but not
with the trans isomer [18].
The complex Co3(
obtained serendipitously from
CC„CSiMe3)(
-dppm)(CO)7 and RuCl(dppe)Cp* containing PPh3
31P NMR detection) and was initially characterised by the XRD
structure determination (below). Its spectroscopic properties in-
clude (C„C) at 2111, terminal (CO) bands between 2044 and
l3-CC„CSiMe3)(
l-dppm)(CO)6(PPh3) 15 was
a
reaction between Co3(l3
-
l
(
m
m
1937 cmꢀ1, and characteristic resonances for SiMe3 (dH ꢀ0.025)
and dppm (dH 3.29, 4.50). In the 31P NMR spectrum, signals at dP
34.5 and 49.5 (ratio 2/1) were assigned to the dppm and PPh3 li-
gands, respectively. The ES-MS contained [M+Na]+ and [MꢀnCO]+
(n = 0, 1) at m/z 1123, 1100 and 1072, and [MꢀH]ꢀ at m/z 1099.
(CO)
Co
(CO) (PPh )
3
2
3
Co
O
(OC) Co
C
C
2
(OC) Co
C
C
C
SiMe
3
2
Recent structural analyses of conjugated poly-ynes have con-
cluded that experimental limits for C„C triple and C–C single bond
lengths for C(sp) atoms are between 1.208 and 1.216 Å and 1.351
and 1.366 Å, respectively [29]. Computational studies have given
lengths of 1.225 and 1.361 Å [30], while in HC„CH and
HC„CC„CH, the experimental (microwave) C„C separations are
1.2033(1) [31] and 1.20964(14) Å [32], respectively, with the
C(sp)–C(sp) single bond separation in the diyne being
1.37081(2) Å. In general, the C„C and C–C bonds tend to become
longer and shorter, respectively, as the Cx chains lengthen, with
reasonable limits being ca. 1.25 and 1.33 Å for these two bonds
[29].
OEt
Ph P
2
Ph P
2
Co(CO)
Co(CO)
2
2
P
P
Ph
2
Ph
2
15
16
Attempted replacement of Br by azide in the reaction of Co3(l3
CBr)( -dppm)(CO)7 with NaN3 in EtOH gave instead deep green
Co3{ 3-CC(O)OEt}( -dppm)(CO)7 (16), initially identified by the
XRD structure determination reported below. The spectroscopic
properties were in accord with the solid-state structure, with termi-
-
l
l
l
nal
m(CO) bands between 2069 and 1964, and m(ester CO) at
1649 cmꢀ1. The NMR spectra contained resonances for the Et group
(dH 0.93, 4.19) and dppm ligand (dP 35.1).
These complexes are further examples of Co3 clusters support-
ing carbon chains of various lengths attached by a l3 g1 interac-
–
tion with their terminal carbon atoms. The other end-groups in
the present selection are Fc, Ru(dppe)Cp* or SiMe3, while for 13
and 14, we have used an Hg atom to link two Cx chains to give
approximately linear 7- and 11-atom sequences. The reactions
used to prepare these complexes are conventional: coupling of
alkynyl-gold phosphine complexes with iodoalkynes or the
bromocarbyne Co3 cluster, desilylation (NaOMe) of Co3{l3
C(C„C)xSiMe3}( -dppm)(CO)7 in the presence of Hg(OAc)2, or sub-
stitution of CO by PPh3. The formation of the 3-C(CO2Et) complex
-
l
l
likely occurs with NaN3 acting as a base and allowing addition of
OEtꢀ to an intermediate ketenylidene complex.
Cyclic voltammetric studies of 13 and 14 show only one revers-
ible reduction process at E1 = ꢀ1.11 and ꢀ1.09 V, respectively. This
suggests that the presence of the mercury atom blocks electronic
communication along the chain, since analogous tricobalt clusters
containing Cx chains show two reduction processes, consistent
with some electronic interaction between the two terminal clus-
Fig. 1. Projection of a molecule of {Co3(CO)9}{l
3-C(C„C)2}{Ru(dppe)Cp*} (7).

M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
2891
Fig. 2. Projection of a molecule of {Co3(l-dppm)(CO)7}2(l-C14) (12).
CO(22)
222
211
212
221
CO(33)
P(2)
CO(21)
3
Hg
2
1
CO(31)
Co(3)
Co(1)
0
CO(32)
111
P(1)
CO(11)
CO(12)
112
Fig. 3. Projection of a molecule of Hg{C„CC[Co3(l-dppm)(CO)7]}2 (13).
CO(22)
CO(21)
CO(31)
CO(33)
211
212
4
P(2)
Hg
5
3
2
Co(3)
1
0
CO(11)
Co(1)
CO(32)
P(1)
121
111
CO(12)
112
Fig. 4. Projection of a molecule of Hg{(C„C)2C[Co3(l-dppm)(CO)7]}2 (14).
Table 2 summarises the various data pertaining to these bonds
as found in the complexes described above and related compounds
reported elsewhere. Interestingly, both the C„C and C(sp)–C(sp)
separations are at the longer ends of the ranges cited above, sug-
gesting that any lengthening of the C„C triple bond may not be
the result of conjugation (delocalisation). There is a slight but
inconsistent trend towards the inner C„C triple bonds being
shorter than those towards the metal end-cap, paralleling the
trend observed for other poly-ynes surveyed. Of further interest
is the observation that the C„C triple bonds in carbon chains
which have both ends capped by metal centres involved in tri-
ply-bonding C„M interactions appear to be somewhat shorter
(av. 1.205 Å) than those in the other complexes considered here
(av. 1.224 Å). The separation between the carbon atom attached

2892
M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
involved in carbynic interactions with either an M3 cluster or an
M(CO)2Tp group.
5. Experimental
5.1. General
All reactions were carried out under dry nitrogen, although nor-
mally no special precautions to exclude air were taken during sub-
sequent work-up. Common solvents were dried, distilled under
nitrogen and degassed before use. Separations were carried out
by preparative thin-layer chromatography on glass plates
(20 ꢁ 20 cm2) coated with silica gel (Merck, 0.5 mm thick).
5.2. Instruments
IR spectra were obtained using a Bruker IFS28 FT-IR spectrom-
eter. Spectra in CH2Cl2 were obtained using a 0.5 mm path-length
solution cell with NaCl windows. Nujol mull spectra were obtained
from samples mounted between NaCl discs. NMR spectra were re-
corded on a Varian 2000 instrument (1H at 300.13 MHz, 13C at
75.47 MHz, 31P at 121.503 MHz). Unless otherwise stated, samples
were dissolved in CDCl3 contained in 5 mm sample tubes. Chemical
shifts are given in ppm relative to internal tetramethylsilane for 1H
and 13C NMR spectra and external H3PO4 for 31P NMR spectra. Elec-
trospray mass spectra (ES-MS) were obtained from samples dis-
solved in MeOH containing NaOMe as an aid to ionisation [34].
Solutions were injected into a Fisons VG Platform II spectrometer
via a 10 ml injection loop. Nitrogen was used as the drying and
nebulising gas. Peaks listed are the most intense of the isotopic
clusters. Electrochemical samples (1 mM) were dissolved in CH2Cl2
containing 0.5 M [NBu4]BF4 as the supporting electrolyte. Cyclic
voltammograms were recorded using a PAR model 263 apparatus,
with a saturated calomel electrode. A 1 mm path-length cell was
used with a Pt-mesh working electrode, Pt wire counter and pseu-
do-reference electrodes. Ferrocene was used as internal calibrant
(FeCp2/[FeCp2]+ = +0.46 V). Elemental analyses were by CMAS,
Belmont, Vic., Australia.
Fig. 5. Projection of a molecule of Co3(l3-CC„CSiMe3)(l-dppm)(CO)6(PPh3) (15).
5.3. Reagents
Fig. 6. Projection of a molecule of Co3{l3-CC(O)OEt}(l-dppm)(CO)7 (16).
The compounds FcC„CI [13], Co3(
l
3-CBr)(
-dppm)(CO)7 (x = 1, 2) [25a] and
l-dppm)(CO)7 (x = 1, 2) [9], IC„CC„CSiMe3
l-dppm)(CO)7 [25b],
Co3{
Co3{
l
3-C(C„C)Au(PPh3)}(
l
l3-C(C„C)xSiMe3}(
to the Co3 cluster (formally sp hybridised) and the next atom in the
chain ranges from 1.30(3) (in 12) to 1.397(3) Å (in 15), the ex-
tremes in the more precise determination reflecting the relativities
in strong electron-donating and -withdrawing powers, respec-
tively, of the other end-capping groups. Angles at the poly-yne car-
bons range between 169.8(3)° and 179.5(9)°, with no consistent
trends found. The usual conclusion that distortions along the Cx
chains are due to ‘‘crystal packing effects” allied with intrinsically
low bending force constants is not contradicted here.
and I(C„C)xI (x = 3, 4) [10,14] were prepared by the cited
methods.
5.3.1. Co3{
l3-C(C„C)4SiMe3}(
l-dppm)(CO)7 (3)
A solution containing Co3{
l3-C(C„C)2Au(PPh3)}(l-dppm)(CO)7
(200 mg, 0.156 mmol) and IC„CC„CSiMe3 (38.7 mg, 0.156 mmol)
in thf (7 ml) was treated with CuI (2 mg, 0.0078 mmol) and
Pd(PPh3)4 (9 mg, 0.0078 mmol) and stirred at r.t. for 1 h. After re-
moval of solvent and extraction of the residue with acetone–hex-
ane (3/7), chromatography on silica gel using the same solvent
gave two bands. Band
1
(brown) contained Co3{l3-C-
4. Conclusions
(C„C)4SiMe3}( -dppm)(CO)7 (3) (100 mg, 68%), isolated as small
l
very dark brown-red crystals. Anal. Calc. for C44H31Co3O7P2Si: C,
In this account, we have described several complexes contain-
55.01; H, 3.31. Found: C, 54.98; H, 3.31%. M, 938. IR (cyclohexane,
ing carbon chains end-capped by Co3(l-dppm)(CO)7 clusters, with
cmꢀ1):
m(C„C) 2156vw, 2141vw, 2113vw; m(CO) 2067s, 2047 m,
other metal-containing fragments at the other end. Included in
these are two compounds in which a mercury atom bridges two
cluster-terminated chains. Consideration of available structural
data confirms the major conclusions of earlier surveys [30,33],
highlighting an apparent tendency for the C„C triple bond lengths
in these complexes to be at the longer end of the range found, with
shorter bonds occurring when the terminal poly-yne carbons are
2024 (sh), 2019vs, 2007 (sh), 1991w, 1982w. 1H NMR: d 0.30 (s,
9H, SiMe3), 3.47, 4.30 (2 ꢁ m, 2H, CH2), 7.26–7.56 (m, 20H, Ph).
13C NMR: d ꢀ0.27 (s, SiMe3), 43.82 [t, J(CP) = 35 Hz, CH2], 63.59,
64.34, 70.60, 80.90, 89.38, 91.56, 96.34, 98.76 (8 ꢁ s, C9 carbons),
128.78–135.01 (m, Ph), 201,42 [s (br), CO]. 31P NMR: d 34.2 [s
(br), dppm]. ES-MS (positive ion, MeOH+NaOMe, m/z): 889,

M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
2893
Table 1
Selected bond distances (Å) and angles (°)
Complex
7
12
13
14
15
16
Bond distances (Å)
Co(1)ACo(2)
Co(1)ACo(3)
Co(2)ACo(3)
Co(1)AP(1)
Co(2)AP(2)
Co(1)AC(1)
Co(2)AC(1)
Co(3)AC(1)
C(1)AC(2)
2.4776(7)
2.4853(9)
2.4647(8)
2.449(4)
2.445(4)
2.448(4)
2.154(6)
2.180(6)
1.96(2)
1.92(2)
1.92(2)
1.30(3)
1.25(3)
1.38(2)
1.24(2)
2.486(1)
2.497(1)
2.479(1)
2.199(2)
2.201(2)
1.898(5)
1.898(5)
1.931(5)
1.397(7)
1.220(8)
1.973(5) [Hg]
2.482(1)
2.467(1)
2.484(1)
2.196(2)
2.201(2)
1.898(7)
1.921(7)
1.943(7)
1.38(1)
1.23(1)
1.36(1) [C(4)]
1.25(1)
2.4946(3)
2.4860(3)
2.4789(4)
2.2155(6)
2.1974(6)
1.924(2)
1.922(2)
1.922(2)
1.397(3)
1.224(3)
2.4834(3)
2.4722(3)
2.4885(3)
2.2036(4)
2.2052(4)
1.887(1)
1.881(1)
1.925(1)
1.470(2)
1.208(2) [O(2)]
1.498(3) [C(4)]
1.925(3)
1.919(3)
1.931(3)
1.367(4)
1.231(4)
1.350(4) [C(4)]
1.236(4)
C(2)AC(3)
C(3)AX
C(4)AC(5)
1.830(2) [Si]
Co(1)ACO
Co(2)ACO
Co(3)ACO
1.819, 1.800, 1.792(5)
1.829, 1.796, 1.794(6)
1.823, 1.799, 1.782(4)
1.75(3), 1.73(2)
1.75(2), 1.73(2)
1.80(2), 1.74(2), 1.74(2)
1.815, 1.794(7)
1.799, 1.778(6)
1.813, 1.796, 1.812(7)
1.801, 1.783(8)
1.820, 1.786(8)
1.807, 1.797, 1.776(9)
1.793, 1.781(2)
1.804, 1.783(2)
1.782, 1.762(2)
1.780, 1.784(2)
1.793, 1.790(2)
1.816, 1.788, 1.795(2)
Bond angles (°)
Co(1)AC(1)AC(2)
Co(2)AC(1)AC(2)
Co(3)AC(1)AC(2)
C(1)AC(2)AC(3)
C(2)AC(3)AX
133.0(2)
133.8(2)
129.4(3)
177.6(3)
178.4(3) [C(4)]
174.0(3)
130(2)
134(2)
136(2)
174(2)
171(2) [C(4)]
175(2)
129.7(4)
138.1(4)
125.2(4)
178.0(6)
138.4(6)
129.5(5)
127.2(5)
177.8(7)
178.4(8) [C(4)]
177.7(8)
130.5(1)
129.3(1)
135.1(1)
176.1(2)
173.0(2) [Si]
137.9(1)
132.0(1)
121.8(1)
172.7(5) [Hg]
C(3)AC(4)AC(5)
For 7: For the Ru(dppe)Cp* fragment: RuAP(1,2) 2.2666, 2.2752(9), RuAC(cp) 2.238–2.275(3) [av. 2.259(15)], RuAC(5) 1.955(3) Å; P(1)ARuAP(2) 84.84(3)°, P(1,2)ARuAC(5)
84.61°, 83.28(9)°.
For 12: C(5)AC(6) 1.32(3), C(6)AC(7) 1.18(3), C(7)AC(70) 1.33(4) Å; C(4)AC(5)AC(6) 176(2)°, C(5)AC(6)AC(7) 178(2)°, C(6)AC(7)AC(70) 175(3)°.
For 13: C(3)AHgAC(30) 180°.
For 14: Hg–C(5) 1.985(6) Å; C(4)AC(5)AHg 175.4(6)°, C(5)AHgAC(50) 180°.
For 15: Co(3)AP(3) 2.2221(6), SiAC(101,102,103) 1.864, 1.862, 1.864(2) Å.
For 16: C(2)AO(3) 1.345(2), O(3)AC(3) 1.447(2) Å.
[M+H+NaꢀSiMe3]+; (negative ion): 865, [MꢀSiMe3]ꢀ; 837,
2H, CH2), 4.45 (s, 5H, Cp), 6.94–7.51 (m, 50H, Ph). 13C NMR: d
39.61 [s (br), dppm], 86.01, 100.79, 108.07, 138.35 (C4 chain),
87.18 (s, Cp), 127.40–133.75 (m, Ph), 203.12 [s (br), CO]. 31P
NMR: d 33.6 (s, 2P, dppm), 49.4 (s, 2P, PPh3). ES-MS (positive ion,
MeOH+NaOMe, m/z): 1531, [M+Na]+; (negative ion, MeOH+
NaOMe): 1507, [MꢀH]ꢀ.
[MꢀSiMe3ꢀCO]ꢀ. Band 2 contained {Co3(
l-dppm)(CO)7}2(l-C10)
(30 mg, 23%), identified by comparison with an authentic sample
[9].
5.3.2. Co3{
NaOMe [from Na (5.5 mg) in MeOH (1 ml)] was added to a solu-
tion of Co3{ 3-C(C„C)4SiMe3}( -dppm)(CO)7 (78 mg, 0.08 mmol)
l3-C(C„C)4Au(PPh3)}(l-dppm)(CO)7 (4)
l
l
5.3.4. {Cp*(dppe)Ru}C„CC„CC{Co3(
mixture of Ru{(C„C)2Au[P(tol)3]}(dppe)Cp* (50 mg, 0.05
mmol), Co3( 3-CBr)( -dppm)(CO)7 (45 mg, 0.05 mmol), Pd(PPh3)4
l-dppm)(CO)7} (6)
in thf/MeOH (3/5, 8 ml). After stirring at r.t. for 30 min, AuCl(PPh3)
(41 mg, 0.08 mmol) was added. After stirring a further 2 h, solvent
was removed and the residue was suspended in MeOH (5 ml). The
insoluble brown solid was transferred to a sinter, washed with cold
MeOH and extracted with a minimum of benzene. Addition of hex-
A
l
l
(4 mg, 0.003 mmol) and CuI (1 mg, 0.005 mmol) in thf (7 ml) was
stirred at r.t. for 1 h. Separation by preparative tlc (acetone–hexane
3/7) afforded
{Cp*(dppe)Ru}C„CC„CC{Co3(
was isolated as dark red crystals (PhMe/MeOH). Anal. Calc. for
73H61Co3O7P4Ru: C, 60.38; H, 4.23. Found: C, 60.25; H, 4.17%. M,
1452. IR (cyclohexane, cmꢀ1):
(C„C) 2107vw; (CO) 2062w,
a
major brown band (Rf = 0.44) from which
ane to the filtrate gave Co3{
l
3-C(C„C)4Au(PPh3)}(
l
-dppm)(CO)7
l-dppm)(CO)7} (6) (52.7 mg, 69.5%)
(4) (84 mg, 76%) as a brown powder. Anal. Calc. for C59H37Au-
Co3O7P3: C, 53.47; H, 2.80. Found: C, 53.41; H, 2.74%. M, 1324. IR
C
(CH2Cl2, cmꢀ1):
m
(C„C) 2140w (br);
m
(CO) 2063 s, 2015vs, 1984
m
m
(sh), 1972 (sh). 1H NMR: d 3.45, 4.30 (2 ꢁ m, 2 H, CH2), 7.25–7.54
(m, 35 H, Ph). 31P NMR: d 33.9 [s (br), 2P, dppm], 41.2 [s (br), 1P,
PPh3]. ES-MS (positive ion, MeOH, m/z): 1325, [M+H]+; 1324, M+;
1296, [MꢀCO]+; (MeOH+NaOMe): 1347, [M+Na]+.
2044 m, 2009 s, 2003vs, 1989 (sh), 1976vw, 1968vw, 1952vw. 1H
NMR: d 1.59 (s, 15H, Cp*), 2.03, 2.69 (2 ꢁ m, 2 ꢁ 2H, dppe), 3.21,
4.52 (2 ꢁ m, 2 ꢁ 1H, dppm), 7.03–7.70 (m, 40H, Ph). 13C NMR: d
10.13 (s, C5Me5), 29.69 [s (br), dppe], 38.38 (s, dppm), 86.08,
96.09, 109.60, 137.61 (C4 chain), 93.64 (s, C5Me5), 127.42–133.38
(m, Ph), 202.83, 203.35, 210.32 (CO). 31P NMR: d 33.5 (s, 2P, dppm),
79.45 (s, 2P, dppe). ES-MS (positive ion, MeOH, m/z): 1452, M+;
1424, 1396 [MꢀnCO]+ (n = 1, 2); (negative ion, MeOH+NaOMe):
1452, Mꢀ.
5.3.3. {Cp(Ph3P)2Ru}C„CC„CC{Co3(
A mixture of Ru{(C„C)2Au[P(tol)3]}(PPh3)2Cp* (71 mg, 0.06
mmol), Co3( 3-CBr)( -dppm)(CO)7 (51 mg, 0.06 mmol), Pd(PPh3)4
l-dppm)(CO)7} (5)
l
l
(7 mg, 0.006 mmol) and CuI (1 mg, 0.005 mmol) in thf (10 ml)
was stirred at r.t. for 2 h to give a brown solution. Separation by
preparative tlc (acetone–hexane 3/7) afforded a major brown band
5.3.5. {Cp*(dppe)Ru}C„CC„CC{Co3(CO)9} (7)
(Rf = 0.38) from which {Cp(Ph3P)2Ru}C„CC„CC{Co3(
l-dppm)
A solution of Ru{C„CC„CAu(PPh3)}(dppe)Cp* (150 mg, 0.13
(CO)7} (5) (69.4 mg, 77%) was isolated as dark red crystals
(PhMe/MeOH). Anal. Calc. for C78H57Co3O7P4Ru: C, 62.11; H, 3.78.
Found: C, 62.12; H, 3.73%. M, 1508. IR (cyclohexane, cmꢀ1):
mmol) and Co3(l3-CBr)(CO)9 (67.7 mg, 0.13 mmol) in thf
(10 ml) was treated with Pd(PPh3)4 (8.1 mg, 0.007 mmol) and
CuI (2 mg, 0.1 mmol). After stirring at r.t. for 30 min, spot tlc
showed the absence of starting material. Removal of thf under
reduced pressure and purification of a CH2Cl2 extract of the
m
(C„C) 2108vw; m(CO) 2063w, 2046 m, 2005 (sh), 2004vs, 1985
(sh), 1976 (sh), 1968w, 1952vw. 1H NMR: d 3.38, 4.61 (2 ꢁ m,

2894
M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
Table 2
Bond lengths and angles along Cx (x P 5) chains attached to Co3(
l
-dppm)(CO)7 end-groups
„C3AC4„
Entry Complexa „C1AC2„ AC2„C3A
AC4„C5A
„C5AC6„
AC6„C7A
„C7AC8„
Reference
„C1AC2„C3A AC2„C3AC4„ „C3AC4„C5A AC4„C5AC6„ „C5AC6„C7A AC6„C7AC8„ „C7AC8„C9A
c
1
[Co3]C5Fc
1.385(2)
176.6(2)
1.377(5)
178.8(5)
1.367(4)
177.6(3)
1.42(1)
177.8(8)
1.383(10)
178.8(8)
1.383(10)
177.8(7)
1.380(3)
179.3(3)
1.385(3)
177.6(3)
1.381(6)
178.0(4)
1.398(7)
177.7(5)
1.393(7)
178.3(8)
1.367–1.42
(1.388)
1.227(2)
176.7(2)
1.219(5)
178.5(4)
1.231(4)
178.4(3)
1.21(1)
179.5(9)
1.23(1)
176.7(8)
1.23(1)
178.4(8)
1.226(3)
177.5(3)
1.230(3)
174.1(3)
1.224(7)
173.0(4)
1.225(7)
177.6(5)
1.226(7)
178.9(8)
1.213–1.231
(1.225)
1.364(2)
177.6(2)
1.367(6)
178.4(4)
1.350(4)
174.0(3)
1.37(1)
173.5(8)
1.36(1)
177.2(8)
1.36(1)
177.7(8)
1.345(3)
178.2(3)
1.355(4)
177.6(3)
1.343(7)
175.5(4)
1.350(7)
177.6(5)
1.356(7)
175.8(8)
1.341–1.365
(1.353)
1.215(2)
177.0(2)
1.216(6)
177.0(4)
1.236(4)
176.6(3)
1.19(1)
177.8(8)
1.22(1)
177.6(6)
1.25(1)
175.4(6)
1.219(4)
169.8(3)
1.217(4)
176.1(3)
1.226(7)
175.7(4)
1.232(7)
177.8(5)
1.220(7)
174.4(9)
1.214–1.236
(1.226)
2
[Co3]C5[W]
[24a]
3
[Co03]C5[Ru*] 7
{[Co3]C5}2[Pt]
[Co3]C5[Au]
{[Co3]C5}2Hg (14)
[Co3]C5R[Co3]
[Co3]C7Ph
This work
[18]
4
5
[24a]
6
This work
[9]
7
8
1.366(4)
176.9(3)
1.357(7)
178.3(4)
1.348(7)
176.8(5)
1.350(7)
173.1(9)
1.348–1.366
(1.355)
1.203(4)
178.4(3)
1.208(7)
175.9(4)
1.241(6)
176.9(4)
1.228(7)
171.6(7)
1.203–1.241
(1.220)
[8b]
9
[Co3]C7SiMe3
[Co3]C7[Ru*]
[Co3]C7[Ru]
[8b]
d
10
11
d
Ranges for entries 1–11
(averages)
176.1–179.3
(177.8)
172.7–179.5
(176.0)
174.0–178.2
(176.8)
169.8–177.8
(175.4)
173.1–178.3
(176.2)
171.6–178.4
(175.7)
12
13
14
15
16
17
18
[Co3]C6[Mo]
[Co3]C6[Ru3]
[Co3]C6[Os3]
1.371(6)
178.7(7)
1.43(3)
177(3)
1.41(3)
1.231(6)
179.9(6)
1.15(3)
180(2)
1.17(2)
1.332(6)
177.8(6)
1.39(3)
168(2)
1.40(2)
1.246(6)
176.7(6)
1.19(3)
174(3)
1.14(3)
1.355(6)
[24f]
[24c]
[24c]
[9]
1.46(3)
1.44(3)
177(2)
174(2)
175(2)
1.346(3)
172(2)
b
[Co3]2C6
1.377(3)
175.6(2)
1.376(2)
176.1(2)
1.30(3)
174(2)
1.371(6)
176.4(5)
1.225(3)
177.9(2)
1.226(3)
173.3(2)
1.25(3)
b
[Co3]2C10
1.345(3)
176.8(2)
1.38(3)
1.221(3)
178.4(2)
1.24(3)
1.347(3)
[9]
b
[Co3]2C14 (12)
1.32(3)
178(2)
1.339(8)
178.4(6)
1.339–1.463
(1.388)
1.18(3)
175(3)
1.221(8)
178.6(6)
1.33(4)
This work
[8a]
171(2)
175(2)
176(2)
b
[Co3]2C16 (9)
1.221(8)
169.7(6)
1.147–1.230
(1.203)
1.335(8)
176.2(6)
1.333–1.398
(1.357)
1.228(8)
178.8(6)
1.145–1.246
(1.206)
1.342(9)
179.5(7)
Ranges for entries 12–16, 18 1.371–1.440
(averages)
(1.391)
175.6–178.4
(176.7)
169.7–179.8
(177.4)
167.4–177.6
(174.5)
171.6–178.8
(176.0)
-dppm)(CO)7; [Co03] = Co3(CO)9; R = C[@C(CN)2]C[@C(CN)2]C; [W] = W(CO)3Cp; [Ru*] = Ru(dppe)Cp*; [Pt] = trans-Pt(PPh3)2; [Au] = Au{P(tol)3}; [Ru] =
-H)3(CO)9; [Os3] = Os3( -H)3(CO)9.
Centrosymmetric; AC(8)„C(9)A 1.211(9)Å.
a
[Co3] = Co3(
l
Ru(dppe)Cp; [Mo] = Mo(CO)2Tp; [Ru3] = Ru3(
l
l
b
c
M.I. Bruce, M. Gaudio, B.W. Skelton, A.H. White, unpublished work.
M.I. Bruce, C.R. Parker, B.W. Skelton, A.H. White, unpublished work.
d
residue by preparative tlc (acetone–hexane, 1/4) gave a major
brown band (Rf = 0.41) containing {Cp*(dppe)Ru}C„CC„CC{Co3-
(CO)9} (7) (58.7 mg, 40%), obtained as dark brown crystals from
0.0025 mmol) and CuI (1 mg, 0.005 mmol) in thf (7 ml) was stirred
at r.t. for 30 min, after which time tlc showed no starting materials
to be present. Evaporation of solvent, dissolution of the residue in
CH2Cl2 and separation on silica plates (acetone–hexane 1/4) gave
two fractions. The major product was isolated from a brown-
hexane. Anal. Calc. for
Found: C, 53.51; H, 3.55%. M, 1124. IR (CH2Cl2, cmꢀ1):
2124vw; (CO) 2094w, 2044vs, 2026s, 2013 (sh), 1976m (br).
C50H39Co3O9P2Ru: C, 53.45; H, 3.50.
m
(C„C)
m
orange band (Rf = 0.26) to give Co3{l3-C(C„C)3Fc}(l-dppm)(CO)7
1H NMR (C6D6): d 1.42 (s, br, 15H, Cp*), 1.92, 2.24 (2 ꢁ m, 4H,
dppe), 7.03–7.67 (m, 20H, Ph). 13C NMR (C6D6): d 10.38 (s,
C5Me5), 29.94 (s, CH2), 94.93 (s, C5Me5), 87.49, 98.91, 114.67
(3 ꢁ s, carbon chain), 130.21–138.40 (m, Ph), 201.45 (s br, CO).
31P NMR (C6D6): d 79.5 (s, dppe). ES-MS (positive ion, MeOH/
NaOMe, m/z): 1147, [M+Na]+; 1124, M+; 1096, [MꢀCO]+; (nega-
tive ion mode, MeOH/NaOMe, m/z): 1155, [M+OMe]ꢀ; 1096,
[MꢀCO]ꢀ.
(8) (40.8 mg, 87%) as very thin red plates. Anal. Calc. for C49H31Co3-
FeO7P2: C, 57.31; H, 3.02. Found: C, 56.74; H, 2.57%. M, 1026. IR
(CH2Cl2, cmꢀ1):
m(C„C) 2168w, 2100vw; m(CO) 2063s, 2013vs,
1973 (sh), 1958 (sh). 1H NMR: d 3.40, 4.25 (2 ꢁ m, 2H, CH2), 4.28
(s, 5H, FeCp), 4.30, 4.56 (2 ꢁ m, 4H, CH2), 7.15–7.69 (m, 20H, Ph).
31P NMR: d 33.8 (s, dppm). 13C NMR: d 42.75 [t, J(CP) 18.3 Hz,
dppm], 70.35 (FeCp), 69.76, 72.35 (Fe–C5H4), 63.38, 65.66, 72.73,
80.95, 85.99, 97.13, 99.03 (Cipso and C6 of carbon chain), 201.43,
209.79, 212.4 (Co–CO), 128.45–134.77 (m, Ph). ES-MS (positive
ion mode, MeOH, m/z): 1027, [M+H]+; 1026, M+; 998, [MꢀCO]+;
(MeOH+NaOMe): 1049, [M+Na]+; (negative ion mode, MeOH+
NaOMe): 1025, [MꢀH]ꢀ.
5.3.6. Co3{
A mixture of Co3{
0.05 mmol), FcC„CI (15.3 mg, 0.05 mmol), Pd(PPh3)4 (3 mg,
l3-C(C„C)3Fc}(l-dppm)(CO)7 (8)
l3-C(C„C)2Au(PPh3)}(l-dppm)(CO)7 (60 mg,

M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
2895
5.4. Syntheses of {Co3(
l
-dppm)(CO)7}2(
l
-Cy)
5.5.2. Hg{(C„C)2C[Co3(l-dppm)(CO)7]}2 (14)
A
solution of Co3{
l
3-C(C„C)2SiMe3}(
l
-dppm)(CO)7 (50 mg,
(a) y = 16, 9:
A
mixture of Co3{
l
3-C(C„C)2Au(PPh3)}(
l
-
0.056 mmol) and Hg(OAc)2 (9 mg, 0.028 mmol) in a mixture of
thf and MeOH (1/3, 4 ml) was treated with NaOMe (excess) in
MeOH (1 ml), and the mixture was stirred at r.t. for 1 h. Removal
of solvent under reduced pressure and separation of a CH2Cl2 ex-
tract of the residue by preparative tlc (silica, acetone–hexane 3/
dppm)(CO)7 (153.1 mg, 0.12 mmol), I(C„C)3I (20 mg, 0.06 mmol),
Pd(PPh3)4 (7 mg, 0.006 mmol) and CuI (1 mg, 0.006 mmol) in thf
(7 ml) was stirred at r.t., the solution rapidly turning dark red. After
1 h, solvent was removed and the residue taken up in CH2Cl2. Sep-
aration by preparative tlc (acetone–hexane, 3/7) gave one dark red-
7) afforded two bands. The red band (Rf = 0.50) contained {Co3(
dppm)(CO)7}2( -C10) (1.5 mg, 3%), identified by comparison with
an authentic sample [9]. The brown band (Rf = 0.48) contained
Hg{(C„C)2C[Co3( -dppm)(CO)7]}2 (14) (38.1 mg, 74%) obtained
l-
purple band (Rf = 0.38) containing {Co3(
l
-dppm)(CO)7}2(
l
-C16) (9)
l
(90.9 mg, 86%), obtained as very dark red crystals (CH2Cl2/MeOH).
Anal. Calc. for C80H44Co6O14P4: C, 56.27; H, 2.58. Found: C, 56.38;
l
H, 2.60%. M, 1706. IR (CH2Cl2, cmꢀ1):
m
(C„C) 2172w, 2157vw,
as dark brown crystals (CH2Cl2/MeOH). Anal. Calc. for C74H44Co6-
2127vw;
m
(CO) 2065s, 2020vs, 2008 (sh), 1990 (sh), 1986m (br),
HgO14P4: C, 48.42; H, 2.40. Found: C, 48.30; H, 2.47%. M, 1834. IR
1960 (sh). 1H NMR: d 3.46, 4.25 (2 ꢁ m, 2 ꢁ 2H, CH2), 6.97–7.58
(m, 40H, Ph). 13C NMR: d 44.51 [s (br), dppm], 64.36, 66.66,
6828, 70.22, 81.45, 95.98, 99.83 (7 ꢁ s, C14 chain), 124.21–136.43
(m, Ph), 201.06 [s (br), CO]. 31P NMR: d 33.9 [s (br), dppm]. ES-
MS (positive ion, MeOH+NaOMe, m/z): 1729, [M+Na]+; (negative
ion, MeOH); 1705, [MꢀH]ꢀ; 852, [Co3(C8)(dppm)ꢀH]ꢀ. Some
(CH2Cl2, cmꢀ1):
m(C„C) 2112w (br); m(CO) 2061s, 2014vs, 1995
(sh), 1971 (sh). 1H NMR: d 3.45, 4.29 (2 x m, 4H, CH2), 7.18–7.52
(m, 40H, Ph). 13C NMR: d 42.76 [t, J(CP) 22 Hz, dppm], 92.33,
96.16 (s, carbon chain), 128.57–135.28 (m, Ph), 201.67, 209.91,
214.93 (3 ꢁ s, br, Co-CO). 31P NMR: d 34.6 (s, br, dppm). ES-MS (po-
sitive ion mode, MeOH+NaOMe, m/z): 1859, [M+Na]+; (negative ion
mode, MeOH+NaOMe, m/z): 1835, [MꢀH]ꢀ.
{Co3(
(b) y = 26, 10; 18, 11: A mixture of Co3{
-dppm)(CO)7 (70 mg, 0.05 mmol) and I(C„C)4I (10 mg,
l-dppm)(CO)7}2(
l-C10) [9] (3 mg) is formed as a by-product.
l3-C(C„C)4Au(PPh3)}
5.5.3. Thermolysis of Hg{C(C„C)2[Co3(
solution containing Hg{C(C„C)2[Co3(
(20 mg, 0.011 mmol) in thf (5 ml) was heated at reflux point for
1 h. The usual work-up afforded {Co3( -dppm)(CO)7}2( -C10) [9]
l-dppm)(CO)7]}2 (14)
(l
A
l-dppm)(CO)7]}2
0.025 mmol) in thf (7 ml) was treated with Pd(PPh3)4 (2 mg) and
CuI (2 mg). After stirring at r.t. for 1 h, the solution was brown-
red and spot tlc showed the absence of starting material. Separa-
tion by preparative tlc (acetone–hexane 3/7) gave two major bands
and a black base-line. The faster moving purple band (Rf = 0.31)
l
l
(5 mg, 27%). This reaction is accompanied by a considerable
amount of decomposition.
contained {Co3(
dark microcrystals. IR (CH2Cl2, cmꢀ1):
(CO) 2094w, 2065s, 2019vs, 1978 (sh), 1928 (sh). 1H NMR: d
l
-dppm)(CO)7}2(
l
-C26) (10) (20.3 mg, 39%) as very
5.5.4. Co3(
This complex was isolated from the products of the reaction be-
3-CC„CSiMe3)( -dppm)(CO)7 (100 mg, 0.115 mmol),
l3-CC„CSiMe3)(l-dppm)(CO)6(PPh3) (15)
m
(C„C) 2168vw, 2129vw;
m
3.50, 4.24 (2 ꢁ m, 2 ꢁ 2H, CH2), 7.31–7.62 (m, 40H, Ph). 31P NMR:
d 34.0 [s (br), dppm]. ES-MS (positive ion, MeOH+NaOMe, m/z):
1849, [M+Na]+; (negative ion, MeOH+NaOMe, m/z): 1857,
[M+OMe]ꢀ; 1825, [MꢀH]ꢀ (calc. M, 1826). This complex partly
decomposes on plates and in solution, and a satisfactory elemental
analysis could not be obtained. The second dark red band
tween Co3(
l
l
RuCl(dppe)Cp* (77.3 mg, 0.115 mmol) and KF (6.5 mg,
0.113 mmol), which were heated in a refluxing mixture of thf/
MeOH (1/5, 12 ml) for 5 h. After removal of solvents, preparative
tlc of a CH2Cl2 extract (acetone–hexane. 3/7) afforded a major
green-brown band (Rf = 0.44) containing Co3(l3-CC„CSiMe3)(l-
(Rf = 0.29) gave {Co3(l-dppm)(CO)7}2(l-C18) 11 (5.3 mg, 13%) as a
dppm)(CO)6(PPh3) (15) (45.1 mg, 35%), which gave dark red crystals
from CH2Cl2/MeOH. Anal. Calc. for C55H46Co3O6P3Si: C, 60.01; H,
4.21. Found: C, 60.19; H, 4.92%. M, 1100. IR (CH2Cl2, cmꢀ1):
dark red powder. Anal. Calc. for C82H44Co6O14P4: C, 56.88; H,
2.54. Found: C, 56.81; H, 2.60%. M, 1730. IR (CH2Cl2, cmꢀ1):
m
(C„C) 2154vw, 2123vw; m(CO) 2094w, 2065m, 2020vs, 1967m
m
(C„C) 2111vw; m(CO) 2044w, 2024vs, 1992vs, 1971 m (br),
(br), 1927 (sh). 1H NMR: d 3.46, 4.24 (2 ꢁ m, 2 ꢁ 2H, CH2), 7.27–
7.71 (m, 40H, Ph). 31P NMR: d 34.1 [s (br), dppm]. ES-MS (positive
ion, MeOH+NaOMe, m/z): 1753, [M+Na]+; (negative ion, MeOH+
NaOMe, m/z): 1729, [MꢀH]ꢀ.
1937 (sh). 1H NMR: d ꢀ0.025 (s, 9H, SiMe3), 3.29, 4.50 (2 ꢁ m, 4H,
CH2), 6.93–7.55 (m, 35H, Ph). 31P NMR: d 34.5 (s (br, 2P, dppm),
49.5 (s br, 1P, PPh3). ES-MS (positive ion, MeOH+NaOMe, m/z):
1123, [M+Na]+; 1100, M+; 1072, [MꢀCO]+; (negative ion, MeOH+
NaOMe, m/z): 1099, [MꢀH]ꢀ. The source of the PPh3 is likely an
impurity in the starting Ru complex, subsequently confirmed by a
31P NMR spectrum of the latter.
5.5. Syntheses of Hg{(C„C)xC[Co3(l-dppm)(CO)7]}2 (x = 1, 13; 2, 14)
5.5.1. Hg{C„CC[Co3(
l
-dppm)(CO)7]}2 (13)
3-CC„CSiMe3)(l-dppm)(CO)7 (50 mg,
A
solution of Co3(
l
5.5.5. Co3{
l3-CC(O)OEt}(l-dppm)(CO)7 (16)
0.058 mmol) and Hg(OAc)2 (9.2 mg, 0.029 mmol) in a mixture of
thf and MeOH (1/1, 6 ml) was treated with NaOMe (excess) in
MeOH (1 ml), and the mixture was stirred at r.t. for 2 h. Removal
of solvent under reduced pressure and separation of a CH2Cl2
extract of the residue by preparative tlc (silica, acetone–hexane
3/7) afforded two bands. The red band (Rf = 0.53) contained
A suspension of Co3(
l
3-CBr)( -dppm)(CO)7 (75 mg, 0.09 mmol)
l
and NaN3 (35 mg, 0.54 mmol) in degassed EtOH (7 ml) was heated
at reflux point until tlc showed the absence of starting complex
(2 h). The filtered solution as evaporated and a CH2Cl2 extract was
purified by preparative tlc (CH2Cl2/hexane 1/1). The major dark
green band (Rf 0.44) contained Co3{l3-CC(O)OEt}(l-dppm)(CO)7
{Co3(
son with an authentic sample [9]. The brown band (Rf = 0.47)
contained Hg{C„CC[Co3( -dppm)(CO)7]}2 (13) (6.9 mg, 13%) ob-
l-dppm)(CO)7}2(l-C10) (2.5 mg, 5.5%), identified by compari-
(16) (30.7 mg, 41%), obtained as dark green crystals (pentane). Anal.
Calc. for C36H27Co3O9P2: C, 51.31; H, 3.21. Found: C 51.64; H, 3.23%.
M, 842. IR (cyclohexane, cmꢀ1):
m
(CO) 2069s, 2026vs, 2004m,
l
1991w, 1980w, 1964w;
m
(ester CO) 1649w (br). 1H NMR: d 0.93 [s
tained as dark brown crystals (CH2Cl2/MeOH). Anal. Calc. for
C70H44Co6HgO14P4: C, 47.03; H, 2.46. Found: C, 46.92; H, 2.42%.
(br), 3H, CH2Me], 3.50, 4.62 (2 ꢁ m, 2H, CH2), 4.19 [s (br), 2H,
M, 1786. IR (CH2Cl2, cmꢀ1):
m(C„C) 2124vw; m(CO) 2060s,
CH2Me], 7.13–7.51 (m, 20H, Ph). 31P NMR: d 35.1 [s (br), dppm].
2005vs (br), 1985 (sh), 1968 (sh), 1948 (sh). 1H NMR: d 3.47,
4.53 (2 ꢁ m, 4H, CH2), 7.22–7.53 (m, 40H, Ph). 31P NMR: d 34.8
(s, br, dppm). ES-MS (positive ion mode, MeOH+NaOMe, m/z):
1811, [M+Na]+; (negative ion mode, MeOH + NaOMe, m/z): 1787,
[MꢀH]ꢀ.
5.6. Structure determinations
Full spheres of diffraction data were measured using CCD area-
detector instruments. Ntot reflections were merged to N unique

2896
M.I. Bruce et al. / Journal of Organometallic Chemistry 693 (2008) 2887–2897
Table 3
Crystal data and refinement details
Complex
7
12
13
14
15
16
Formula
MW
Crystal system
Space group
a (Å)
C
50H39Co3O9P2Ru
C78H44Co6O14P4
1682.68
Monoclinic
P21/n
8.951(7)
20.213(10)
18.90(1)
C70H44Co6HgO14P4
1787.19
Monoclinic
P21/c
10.0415(9)
22.681(2)
15.480(1)
C74H44Co6HgO14P4 ꢂ 2CH2Cl2
2005.10
Monoclinic
P21/n
10.100(2)
17.675(3)
C55H46Co3O6P3Si
1100.77
C36H27Co3O9P2
842.31
Monoclinic
P21/n
12.3198(3)
25.563(1)
12.8938(7)
1123.67
Monoclinic
P21/c
17.378(3)
14.299(2)
19.338(3)
Triclinic
ꢀ
P1
12.009(1)
12.131(1)
18.836(2)
90.832(2)
96.323(2)
112.721(2)
2511
b (Å)
c (Å)
21.151(4)
a
(°)
b (°)
98.744(4)
93.73(2)
91.649(2)
93.681(3)
95.054(3)
c
(°)
V (Å3)
4749
1.571
4
3412
1.637
2
3524
1.684
2
3768
1.767
2
3570
1.567
4
qc (g cmꢀ3
Z
)
1.456
2
2hmax (°)
66
1.46
45
1.59
55
3.7
53
3.6
65
1.15
68
1.52
l
(Mo K
a
) (mmꢀ1
)
Tmin/max
0.79
0.53
0.79
0.79
0.85
0.86
Crystal dimensions (mm3)
0.48 ꢁ 0.25 ꢁ 0.10
0.48 ꢁ 0.09 ꢁ 0.03
26214
4304 (0.19)
2476
0.18 ꢁ 0.07 ꢁ 0.06
0.15 ꢁ 0.05 ꢁ 0.03
0.55 ꢁ 0.25 ꢁ 0.10
0.34 ꢁ 0.19 ꢁ 0.14
Ntot
72241
48251
34197
39527
63697
N (Rint
)
17835 (0.036)
12862
0.050
8081 (0.046)
7036
0.052
7697 (0.072)
5501
0.051
17953 (0.028)
14280
0.035
14341 (0.031)
9832
0.031
No
R
0.116
Rw (nw/a)
T (K)
0.097 (18)
150
0.23 (25)
150
0.098 (42)
170
0.107 (53)
170
0.073 (0.6)
150
0.083 (wR2) (0.047)
100
(e) F. Cataldo (Ed.), Poly-ynes: Synthesis, Properties and Applications, Taylor &
Francis, New York, 2005.
(Rint cited) after ‘‘empirical”/multiscan absorption correction (pro-
prietary software), No with F > 4 (F) being considered ‘‘observed”.
r
[2] (a) G. Palyi, F. Piacenti, L. Marko, Inorg. Chim. Acta Rev. 4 (1970) 109;
(b) B.R. Penfold, B.H. Robinson, Acc. Chem. Res. 6 (1973) 73;
(c) D. Seyferth, Adv. Organomet. Chem. 14 (1976) 97;
(d) G. Schmid, Angew. Chem. 90 (1978) 417. Angew. Chem., Int. Ed. Engl. 17
(1978) 392;
All data were measured using monochromatic Mo K
a radiation,
k = 0.71073 Å. In the full-matrix least squares refinements on F2
anisotropic displacement parameter forms were refined for the
non-hydrogen atoms, (x, y, z, Uiso H
ing model. Neutral atom complex scattering factors were used;
computation used the XTAL 3.7 [35] [weights: (
2(F2) + nwF2)ꢀ1
and SHELXL 97 [36] [weights: (
2(F2) + (aP)2)ꢀ1 (P = (Fo2 + 2F2c)/3)] pro-
) being included following a rid-
(e) R.D.W. Kemmitt, in: G. Wikinson, F.G.A. Stone, E.W. Abel (Eds.),
Comprehensive Organometallic Chemistry, vol. 5, Pergamon, Oxford, 1982, p.
162 (Chapter 34.3.9);
(f) C.E. Barnes, in: E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), Comprehensive
Organometallic Chemistry II, vol. 8, Pergamon, Oxford, 1995, p. 423 (Chapter
4.3.1.2);
(g) M. Pfeffer, M. Grellier, in: R.H. Crabtree, D.M.P. Mingos (Eds.),
Comprehensive Organometallic Chemistry III, vol. 7, Elsevier, Oxford, 2007,
p. 91 (Chapter 7.01.5.1).
r
]
r
gram systems. Pertinent results are given in the figures (which show
non-hydrogen atoms with 50% probability amplitude displacement
envelopes and hydrogen atoms with arbitrary radii of 0.1 Å, as well
as numbering schemes) and in Tables 1 and 3.
Variata. 12: Weak and limited data supported meaningful aniso-
tropic displacement parameter refinement for Co, P only.
Compound 13: Phenyl ring 22 was modelled as disordered over
two sets of sites, occupancies set at 0.5 after trial refinement.
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Acknowledgements
[8] (a) A.B. Antonova, M.I. Bruce, B.G. Ellis, M. Gaudio, P.A. Humphrey, M. Jevric, G.
Melino, B.K. Nicholson, G.J. Perkins, B.W. Skelton, B. Stapleton, A.H. White, N.N.
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We thank the ARC for support of this work.
(b) A.B. Antonova, M.I. Bruce, P.A. Humphrey, M. Gaudio, B.K. Nicholson, N.
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Appendix A. Supplementary material
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Chem. 670 (2003) 170.
CCDC 656417, 656418, 656419, 656420, 656422, 668738 con-
tain the supplementary crystallographic data for 7, 13, 14, 15, 16
and 12. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/da-
ta_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/j.jorganchem.
2008.06.007.
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