Synthesis, characterization and electrochemical studies of the heterometallic diclusters [{Fe2(μ-CO)(CO)6(μ-PPh2)Au}2(d iphosphine)] (diphosphine=dppm, dppip, dppe, dppp)

Article abstract of DOI:10.1016/S0022-328X(98)00490-2

Treatment of [(ClAu)₂(diphosphine)] {diphosphine=bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)} with two equivalents of the anion [Fe₂(μ-CO)(CO)₆(μ-PPh₂)]^- in the presence of TlBF₄ gives the new heterometallic diclusters [{Fe₂(μ-CO)(CO)₆(μ-PPh₂)Au}₂(d iphosphine)] that have been isolated and characterized. Their ³¹P-NMR spectra show different patterns as a function of the diphosphine ligand. The electrochemical behavior of these compounds has been investigated and compared with that of the mono- [Fe₂(μ-CO)(CO)₆(μ-PPh₂)(μ-AuPPh₃)] and tricluster [{Fe₂(μ-CO)(CO)₆(μ-PPh₂)Au}₃(t riphos)] derivatives.

Full text of DOI:10.1016/S0022-328X(98)00490-2

Journal of Organometallic Chemistry 560 (1998) 147–153
Synthesis, characterization and electrochemical studies of the
heterometallic diclusters [{Fe2(v-CO)(CO)6(v-PPh2)Au}2(diphosphine)]
(diphosphine=dppm, dppip, dppe, dppp)
a
Montserrat Ferrer a,*, Anna Julia` , Roser Reina a, Oriol Rossell a, Miquel Seco a,
Dominique de Montauzon b
a Departament de Qu´ımica Inorga`nica, Uni6ersitat de Barcelona, Mart´ı i Franque´s 1–11, E-08028 Barcelona, Spain
b Laboratoire de Chimie de Coordination du CNRS, 205 Route de Narbonne, 31077 Toulouse Cedex, France
Received 3 December 1997
Abstract
Treatment
of
[(ClAu)2(diphosphine)]
{diphosphine=bis(diphenylphosphino)methane
(dppm),
bis(diphenylphos-
phino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)} with two equiva-
lents of the anion [Fe2(v-CO)(CO)6(v-PPh2)]− in the presence of TlBF4 gives the new heterometallic diclusters
[{Fe2(v-CO)(CO)6(v-PPh2)Au}2(diphosphine)] that have been isolated and characterized. Their 31P-NMR spectra show different
patterns as a function of the diphosphine ligand. The electrochemical behavior of these compounds has been investigated and
compared with that of the mono- [Fe2(v-CO)(CO)6(v-PPh2)(v-AuPPh3)] and tricluster [{Fe2(v-CO)(CO)6(v-PPh2)Au}3(triphos)]
derivatives. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Heterometallic; Clusters; Diphosphine
1. Introduction
chemical studies. For this, the previous formation of
the compounds [{Fe2(v-CO)(CO)6(v-PPh2)Au}(diphos-
phineAuCl)] and [{Fe2(v-CO)(CO)6(v-PPh2)Au}x(tri-
phos)(AuCl)3−x] was thought to be a good starting
point due to the known lability of the chloride that
could be substituted for metal anions. Two routes for
such type of derivatives were considered: (i) the reac-
tion of the phosphido bridged anion [Fe2(v-
CO)(CO)6(v-PPh2)]−, that has already been used as a
building block in the synthesis of [Fe2(v-CO)(CO)6(v-
PPh2)(v-MPPh3)] [2] (M=Au, Ag, Cu) and [{Fe2(v-
CO)(CO)6(v-PPh2)Au}3(triphos)] [3], with the gold
compounds [(ClAu)n(polyphosphine)] in the appropri-
ate molar ratio and (ii) the treatment of the symmetric
complexes [{Fe2(v-CO)(CO)6(v-PPh2)Au}n(polyphos-
phine)] with [(ClAu)n(polyphosphine)] to promote
metal ligand redistribution reactions which are not
usual in the chemistry of gold.
Over the last few years, there have been several
reports [1] dealing with mixed-metal cluster compounds
in which gold diphosphine fragments [Au2(diphosph-
ine)]2+ link two independent cluster units. In order to
gain insight into this type of derivatives, in this paper
we describe the synthesis of several homo polycluster
compounds of the general formula [{Fe2(v-CO)
(CO)6(v-PPh2)Au}2(diphosphine)].
Given that all these species contain identical metal
clusters, it seemed interesting to undertake the synthesis
of compounds with two or more different metal frag-
ments because of their interest in 31P-NMR and electro-
* Corresponding author.
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00490-2

148
M. Ferrer et al. / Journal of Organometallic Chemistry 560 (1998) 147–153
Scheme 1. Reaction of two equivalents of [NEt4][Fe2(v-CO)(CO)6(v-PPh2)] with [(ClAu)2(diphosphine)] in the presence of TlBF4 giving the neutral
metal compounds 1–4.
Scheme 2. Possible conformations of the dppm five-membered and dppe six-membered rings.
2. Results and discussion
CO)(CO)6(v-PPh2)(v-AuPPh3)] [2]. The low tempera-
ture 31P-NMR spectra in CDCl3 solutions varied
according to the diphosphine derivative. For dppip (2)
and dppp (4) typical AX spectra consisting in one
doublet for each type of phosphorus atoms were ob-
tained. However, compounds 1 and 3 displayed two
sets of symmetrically equivalent but magnetically in-
equivalent phosphorus nuclei that gave rise to two
identical AA%XX% patterns. The P–P coupling constants
and chemical shift values were calculated by spectra
The reaction of two equivalents of [NEt4][Fe2(v-
CO)(CO)6(v-PPh2)] with [(ClAu)2(diphosphine)] in the
presence of TlBF4 gave neutral metal compounds of the
type [{Fe2(v-CO)(CO)6(v-PPh2)Au}2(diphosphine)] {di-
phosphine=dppm (1), dppip (2), dppe (3), dppp (4)},
in which the diphosphine acts as a bridge between two
independent cluster units (Scheme 1). The temperature
of the reaction depended on the diphosphine. Whereas
for dppm and dppip derivatives low temperatures were
required to avoid decomposition of the formed prod-
ucts, high yields of dppe and dppp complexes were
obtained at room temperature (r.t.).
3
simulation. Curiously, the coupling constant J(PP) for
2
the dppe derivative was greater (63 Hz) than the J(PP)
for the dppm derivative (17 Hz), in spite of the lower
number of bonds between the phosphorus atoms. This
fact could be interpreted considering the existence or
not of aurophilic interaction. The small coupling con-
stant in compound 1 is consistent with values found in
related compounds where dppm links two independent
Compounds 1–4 were characterized by elemental
analysis as well as IR, H-, 31P- and 13C-NMR. The
1
w(CO) IR pattern for 1–4 is very close, in agreement
with previous data on the related compound [Fe2(v-

M. Ferrer et al. / Journal of Organometallic Chemistry 560 (1998) 147–153
149
Table 1
31P-NMR data for compounds [{Fe2(v-CO)(CO)6(v-PPh2)Au}(diphosphineAuCl)]
Phosphine
PFe2AuP–PAuCl
PFe2AuP–PAuCl
PFe2AuP–PAuCl
dppm
dppip
dppe
45.5 (dd, 2J(PP)=56, 3J(PP)=24)
76.8 (dd, 2J(PP)=37, 3J(PP)=23)
49.9 (dd, 3J(PP)=63, 3J(PP)=25)
46.8 (d, 3J(PP)=24)
19.4 (d, 2J(PP)=56)
49.1 (d, 2J(PP)=37)
31.8 (d, 3J(PP)=63)
26.4 s
131.5 (d, 3J(PP)=24)
133.2 (d, 3J(PP)=23)
129.7 (d, 3J(PP)=25)
129.8 (d, 3J(PP)=24)
dppp
THF solutions were used and P(OMe)3 was the external reference.
metallic units [4] whereas larger constants are found
when M–M interaction exists ([4]a, [5]). On the other
hand, only two exemples of J(PP) are reported in the
dimetallic anion [Fe2(v-CO)(CO)6(v-PPh2)]− and
[(ClAu)2(diphosphine)] in the presence of TlBF4 in a
1:1:1 molar ratio was studied The reaction conditions
were the same as those described above. After 30 min
no further changes were detected by 31P-NMR and a
mixture of symmetric products [{Fe2(v-CO)(CO)6(v-
PPh2)Au}2(diphosphine)], asymmetric products [{Fe2
(v-CO)(CO)6(v-PPh2)Au}(diphosphineAuCl)] and gold
derivative [(ClAu)2(diphosphine)] were obtained
(Scheme 1). Subsequent addition of one further equiva-
lent of the metallic anion and TlBF4 resulted in the
formation of 1–4 as the only products. Interestingly,
the addition of gold derivatives to solutions of pure
compounds 1–4 led to the formation of the mixture
mentioned above.
3
literature for dppe since in most of the compounds
either dppe bridges identical metallic units or acts as a
chelating ligand [6]. The mentioned examples have been
recently described for the compounds [Mn3(CO)12(v3-
H)(v-dppe)AuCl]− ([1]g) (3J(PP)=63 Hz) ([Fe6AuC
(CO)16(v-dppe)AuCl] ([1]i) (3J(PP)=64 Hz), but the
existence or not of interaction between the gold atoms
could not be determined due to the absence of crystal
structures. In spite of this, the relatively large J(PP) in
3 could be indicative of the existence of aurophilic
interaction between the gold atoms of the two cluster
3
units. As a consequence, J(PP) can be expressed as
3+3J(PP).
Although the asymmetric products [{Fe2(v-
CO)(CO)6(v-PPh2)Au}(diphosphineAuCl)] could not
be isolated, 31P-NMR data are shown in Table 1. The
relative large values of the J(PP) coupling constants for
dppm, dppe and dppip derivatives show the possibility
of aurophilic interaction. Remarkably, a 2J(PP)=56
Hz was found for the asymmetric derivative of dppm,
whereas this value was 17 Hz for the symmetric com-
pound 1. This difference could be interpreted in terms
of the existence of aurophilic attraction in the less
sterically-demanding asymmetric compound, where
It is interesting to speculate on the reasons for the
different behavior towards aurophilic attraction be-
tween 1 and 3. Although in the structure of the gold
derivative [(ClAu)2(dppm)] [7], the distance Au–Au is
˚
found at 3.345 A, corresponding to a bonding interac-
tion, the establishment of Au–Au attraction in 1 would
involve the formation of a sterically very constrained
five-membered ring, due to the bulkiness of the sub-
stituents in both arms of the diphosphine (Scheme 2).
In consequence, it seems more reasonable to expect a
conformation in which the two limbs of [{Fe2(v-
CO)(CO)6(v-PPh2)Au}2(dppm)] point away from each
other in order to minimize the sterical demands. On the
other hand, the six-membered ring formed by the more
flexible dppe derivative is much less congested, as can
be observed in Scheme 2, and could allow a certain
degree of aurophilic interaction.
For compound 2, similar behavior of the dppm com-
plex could reasonably be expected. However, it was
impossible to determine the coupling constant value
due to the lack of second order spectrum.
Unfortunately, the existence or not of aurophilic
attraction in 1–4 could not be confirmed structurally,
since all attempts to obtain suitable crystals for X-ray
diffraction studies were unsuccessful.
2
2+3J(PP) could be considered instead of J(PP).
For the dppe derivatives, no variation of the value of
the coupling constant was observed which is consistent
with that both symmetric and asymmetric products
have Au–Au interaction.
The reaction between the anion [Fe2(v-CO)(CO)6(v-
PPh2)]− and the triphosphine derivative [(ClAu)3-
(triphos)] (triphos=1,1,1-tris(diphenylphosphinometh-
yl)ethane) led to similar results. For a 3Fe2:1Au3 molar
ratio, the only compound isolated was [{Fe2(v-
CO)(CO)6(v-PPh2)Au}3(triphos)] (5) [3]. However, for
smaller Fe2:Au3 ratios, a mixture of compounds con-
taining one, two or three Fe2 fragments was obtained.
Again, addition of [(ClAu)3(triphos)] to a solution of
[{Fe2(v-CO)(CO)6(v-PPh2)Au}3(triphos)] led to the for-
mation of, first [{Fe2(v-CO)(CO)6(v-PPh2)Au}2(tri-
phosAuCl)] (5a) and then [{Fe2(v-CO)(CO)6(v-PPh2)-
Au}(triphos)(AuCl)2] (5b), if an excess of gold com-
pound [(ClAu)3(triphos)] was used (Scheme 3).
In order to explore the possibility of obtaining spe-
cies containing AuCl fragments that allow the synthesis
of compounds where di or triphosphines act as a bridge
among different cluster units, the reaction between the

150
M. Ferrer et al. / Journal of Organometallic Chemistry 560 (1998) 147–153
Scheme 3. Reaction of [Fe2(v-CO)(CO)6(v-PPh2)]− with [(ClAu)3(triphos)], leading to the formation of (5), (5a) and (5b), depending on the
concentration of gold compound used.
The ligand redistribution processes observed here are
rather unusual in the chemistry of gold, and only a few
examples have been reported to date [8]. In this case,
their occurrence precluded the isolation of chemically
pure asymmetric complexes and consequently the syn-
thesis of compounds in which the polyphosphines act as
a bridge between different cluster units was impossible.
observe the return peak. Data for oxidation of the
compounds are summarized in Table 2. Cyclic voltam-
mograms of compound 6 are displayed in Fig. 1 as
representative of all compounds.
Controlled potential coulometry at 0.8 V, using a
platinum gauze electrode at r.t. in dichloromethane
with [n-NBu4][BF4] as the supporting electrolyte, indi-
cated that the number of transferred electrons depends
on the number of Fe2Au units present in the compound
(one electron per Fe2Au unit). During this time the
violet solution changes to green and its frozen-glass
EPR spectra shows the resonance attributable to the
2.1. Electrochemical studies
The electrochemical properties of [Fe2(v-CO)
(CO)6(v-PPh2)(v-AuPPh3)] (6), [{Fe2(v-CO)(CO)6(v-
PPh2)Au}2(diphosphine)] {diphosphine=dppm (1), dp-
pip (2), dppe (3), dppp (4)} and [{Fe2(v-CO)(CO)6
(v-PPh2)Au}3(triphos)] (5) were studied in dichlo-
romethane. All of them exhibit an oxidation wave at
about 0.75 V and a reduction process at about −1.4 V.
The reversibility of the first process (oxidation step)
depends on the scan rate. Compounds 3–6 (Fig. 1)
’
radical [Fe2(CO)7(v-PPh2)] by comparison with litera-
ture data [9]. So, we conclude that lifetime of oxidized
compounds is extremely short and an immediate break-
down of Fe–Au bonds after oxidation process gives the
diiron radical together with gold containing decomposi-
tion products.
Bearing all that in mind, the proposed mechanism
(electrochemical and chemical values of n depending on
the nature of the ligand L) is as follows:
show a quasi-reversible process at scan rates \3 Vs−1
whereas for 1 and 2 600 Vs−1 are required in order to
,

M. Ferrer et al. / Journal of Organometallic Chemistry 560 (1998) 147–153
151
peak height of the wave is double compared to that
observed at the oxidation step, with the high values of
DEp consistent with a slow heterogeneous electron
transfer. Exhaustive controlled-potential electrolysis at
−1.80 V consumed twice the amount of electrons than
in the oxidation step, corresponding to a transfer of
two electrons per Fe2Au unit. In the reverse scan, the
voltammograms showed two additional peaks that sug-
gest that chemical reactions occur after reduction. The
peak at −0.13 V (Fig. 1) was attributed to the oxida-
tion of [Fe2(CO)7(v-PPh2)]−
to the radical
’
[Fe2(CO)7(v-PPh2)] when compared with the voltam-
mogram of an authentic sample. The other peak at
about −0.50 V corresponds to an irreversible oxida-
tion probably related to the oxidation of gold–phos-
phine fragments. In view of these findings, the
following mechanism is proposed:
[{Fe2(v-CO)(CO)6(v-PPh2)Au}nL]
−
+X2ne [{Fe2(v-CO)(CO)6(v-PPh2)Au}nL]2n−
−
−2ne
[{Fe2(v-CO)(CO)6(v-PPh2)Au}nL]2n−
“n[Fe2(CO)7(v-PPh2)]− +(Au)nLn−
where L=PPh3, n=1; L=dppm, dppip, dppe, dppp,
n=2; L=triphos, n=3.
As a conclusion from these studies, it can be seen
that in both the oxidation and reduction processes
cleavage of Fe–Au bonds occurs, giving two fragments:
(i) a fragment with Fe–Fe bonds and (ii) some kind of
phosphine–gold derivative. The fact that both oxida-
tion and reduction peak potentials are nearly the same,
independently of the phosphine ligand, clearly indicates
that the electrons involved in these processes belong to
the metallic cores and that there is no electronic com-
munication through the linking phosphine ligands.
Fig. 1. Cyclic voltammograms of compound 6 at 0.1 V s−1. (a)
Oxidation. Dashed line shows the quasi-reversible oxidation wave at
3 V s−1. (b) Reduction.
[{Fe2(v-CO)(CO)6(v-PPh2)Au}nL]
−
−Xne [{Fe2(v-CO)(CO)6(v-PPh2)Au}nL]n+
−
+ne
[{Fe2(v-CO)(CO)6(v-PPh2)Au}nL]n+
“n[Fe2(CO)7(v-PPh2)]+(Au)nLn+
3. Experimental section
where L=PPh3, n=1; L=dppm, dppip, dppe, dppp,
n=2; L=triphos, n=3.
As pointed out above, a reduction process occurred
in the region around −1.4 V (Table 3). The relative
All manipulations were performed under an atmo-
sphere of prepurified N2 with use of standard Schlenk
techniques, and all solvents were distilled from appro-
priate drying agents. IR spectra were recorded in
toluene solutions on an FT-IR 520 Nicolet spectropho-
tometer. 31P{1H}-NMR [l (85% H3PO4)=0.0 ppm],
1H-NMR and 13C-NMR [l (TMS)=0.0 ppm] were
obtained on a Bruker DXR 250 spectrometer. The
Table 2
Cyclic voltammetry data for the oxidation step of compounds 1–6 in
dicloromethane 0.1 M [n-Bu4N][BF4]
Compound
E0 (V)
DEp (mV)
i
p,c/ip,a
n
compounds
[NEt4][Fe2(v-CO)(CO)6(v-PPh2)]
[10],
1
2
3
4
5
6
0.74
0.76
0.75
0.75
0.75
0.71
140a
160a
60b
0.30a
0.30a
0.45b
0.43b
0.60b
0.70b
2
2
2
2
3
1
[Fe2(v-CO)(CO)6(v-PPh2)(v-AuPPh3)] [2], and [{Fe2(v-
CO)(CO)6(v-PPh2)Au}3(triphos)] [3] were prepared as
described previously. The complexes [(ClAu)2
(diphosphine)] and [(ClAu)3(triphos)] were synthesized
and isolated as a solids from a [AuCl(tht)] [11] solution
by adding the appropriate amount of the corresponding
phosphine.
60b
60b
60b
a 600 V s−1 b 3 V s−1
. .

152
M. Ferrer et al. / Journal of Organometallic Chemistry 560 (1998) 147–153
Table 3
Cyclic voltammetry data for the reduction step of compounds 1–6 in dicloromethane 0.1 M [n-Bu4N][BF4] at 0.1 Vs−1
Compound
E0 (V)
DEp (mV)
ip,a/ip,c
E0 (V)
Ep,a (V)a
n
1
2
3
4
5
6
−1.32
−1.40
−1.40
−1.45
−1.47
−1.37
170
170
180
200
180
210
0.35
0.25
0.40
0.45
0.25
0.40
−0.13
−0.13
−0.13
−0.13
−0.13
−0.13
−0.47
−0.62
−0.50
−0.54
−0.62
−0.50
4
4
4
4
6
2
a Ep,a (irreversible oxidation).
Electrochemical measurements were carried out
with an Electrokemat potentiostat [12] using the inter-
rupt method to minimize the uncompensated resis-
tance (IR) drop. Electrochemical experiments were
performed at r.t. in an airtight three-electrode cell
connected to a vacuum argon/N2 line. The reference
electrode consisted of a saturated calomel electrode
(SCE) separated from the non-aqueous solutions by a
bridge compartment. The counter electrode was a spi-
ral of ca. 1 cm2 apparent surface area, made of Pt
wire 8 cm long and 0.5 mm in diameter. The working
electrode was Pt (1 mm) for cyclic voltammetry and
Pt (100 mm) for ultramicroelectrode voltammetry. For
electrolysis experiments, a Pt gauze or foil was used.
The supporting electrolyte was [n-Bu4N][BF4] (Fluka
electrochemical grade), used as received. All solutions
measured were 0.5–1.0×10−3 M in the organometal-
lic complex and 0.1 M in supporting electrolyte. Fer-
rocene (Fc) was used as an internal reference in these
studies, with the redox couple, FcꢀFc+, occurring at
E°=0.42 V versus SCE. E0 values were determined
as the average of cathodic and anodic peak poten-
cials, i.e [(Ep,c+Ep,a)/2].
NMR (240 K, CDCl3): l 7.32–7.05 (m, Ph), 3.74
(t, PCH2P, 2J(H–P)=7.7). 13C-NMR (240 K,
CDCl3): l 138.2–128.1 (m, Ph), 29.3 (t, PCH2P,
1J(C–P)=12). Anal. Calc. for C63H42Au2Fe4O14P4: C
42.89, H 2.40. Found: C 42.99, H 2.60%.
3.2. [{Fe2(v-CO)(CO)6(v-PPh2)Au}2(dppip)] (2)
A similar procedure (reaction temperature 258 K)
was used to prepare compound 2. Yield: 0.32 g, 75%.
IR (toluene, cm−1) w(CO): 2042 (m), 2012 (vs), 1973
(s, br), 1778 (m). 31P{1H}-NMR (240 K, CDCl3): l
133.6 (d, Fe2PPh2, 3J(PP)=23), 78.2 (d, AuPPh2).
1H-NMR (240 K, CDCl3): l 7.46–7.09 (m, Ph), 1.68
(t, PC(CH3)2P, 2J(H–P)=17.3). 13C-NMR (240 K,
CDCl3): l 138.5–125.3 (m, Ph), 39.1 (t, PC(CH3)2P,
2J(C–P)=4), 30.6 (t, PC(CH3)2P, 1J(C–P)=7).
Anal. Calc. for C65H46Au2Fe4O14P4: C 43.53, H 2.59.
Found: C 43.99, H 2.69%.
3.3. Synthesis of
[{Fe2(v-CO)(CO)6(v-PPh2)Au}2(dppe)] (3)
Solid [(ClAu)2dppe] (0.20 g, 0.24 mmol) and TlBF4
(0.14 g, 0.48 mmol) were added to a solution of
[NEt4][Fe2(v-CO)(CO)6(v-PPh2)] (0.30 g, 0.48 mmol)
in 40 ml of THF at r.t. The solution turned deep
violet immediately. After 30 min of stirring the mix-
ture was filtered and taken to dryness. The remaining
solid was extracted with 20 ml of toluene. Subsequent
addition of n-pentane and cooling overnight (233 K)
afforded purple–red microcystals of 3. The compound
was recrystallized in CH2Cl2/n-pentane. Yield: 0.30 g,
70%. IR (toluene, cm−1) w(CO): 2043 (m), 2012 (vs),
1974 (s, br), 1784 (m); 31P{1H}-NMR (240 K,
CDCl3): l 129.8 (m, Fe2PPh2, AA%XX% spin system,
3+3J(PP)=63, 3J(Fe2PPAu)=25, 6J(Fe2PPAu)=0.2,
9J(Fe2PPFe2)=0), 50.7 (m, AuPPh2) (data from spec-
tral simulation). 1H-NMR (298 K, CDCl3): l 7.43–
7.11 (m, Ph), 2.62 (br s, PCH2CH2P). 13C-NMR (298
3.1. Synthesis of
[{Fe2(v-CO)(CO)6(v-PPh2)Au}2(dppm)] (1)
Solid [(ClAu)2dppm] (0.20 g, 0.24 mmol) and TlBF4
(0.14 g, 0.48 mmol) were added to a pre-cooled (268
K) solution of [NEt4][Fe2(v-CO)(CO)6(v-PPh2)] (0.30
g, 0.48 mmol) in 40 ml of THF. The solution turned
deep violet immediately. After 30 min of stirring the
mixture was filtered and taken to dryness. The re-
maining solid was extracted with 10 ml of cold
toluene. Subsequent addition of n-pentane and cool-
ing overnight (233 K) afforded purple–red microcrys-
tals of compound 1. The compound was recrystallized
in CH2Cl2/n-pentane. Yield: 0.25 g, 60%. IR (toluene,
cm−1) w(CO): 2043 (m), 2013 (vs), 1976 (s, br), 1783
(m). 31P{1H}-NMR (240 K, CDCl3): l 130.1 (m,
Fe2PPh2,
AA%XX%
spin
system,
2J(PP)=17,
K, CDCl3):
l
138.3–127.6 (m, Ph), 24.9 (m,
3J(Fe2PPAu)=25, 5J(Fe2PPAu)=0.1, 8J(Fe2PPFe2)=0),
PCH2CH2P). Anal. Calc. for C64H44Au2Fe4O14P4: C
43.23, H 2.49. Found: C 43.51, H 2.68%.
1
42.0 (m, AuPPh2) (data from spectral simulation). H-

M. Ferrer et al. / Journal of Organometallic Chemistry 560 (1998) 147–153
153
3.4. [{Fe2(v-CO)(CO)6(v-PPh2)Au}2(dppp)] (4)
Acknowledgements
A similar procedure was used to prepare compound
4. Yield: 0.32 g, 75%. IR (toluene, cm−1) w(CO): 2042
(m), 2011 (vs), 1972 (s, br), 1781 (m). 31P{1H}-NMR
(240 K, CDCl3): l 129.2 (d, Fe2PPh2,3J(PP)=24),
Financial support for this work was generously given
by DGICYT, Spain (grant no. PB96-0174).
1
47.1(d, AuPPh2). H-NMR (298 K, CDCl3): l 7.59–
References
7.23 (m, Ph), 2.69 (m, 4H, PCH2CH2CH2P), 2.07 (m,
2H, PCH2CH2CH2P). 13C-NMR (298 K, CDCl3): l
[1] (a) R. Reina, O. Rossell, M. Seco, J. Ros, R. Ya´n˜ez, A. Perales,
Inorg. Chem. 30 (1991) 3973. (b) S. Alvarez, O. Rossell, M.
Seco, J. Valls, M.A. Pellinghelli, A. Tiripicchio, Organometallics
10 (1991) 2309. (c) M. Ferrer, R. Reina, O. Rossell, M. Seco, S.
Alvarez, M.A. Pellinghelli, A. Tiripicchio, Organometallics 11
(1992) 3753. (d) A.J. Amoroso, A.J. Edwards, B.F.G. Johnson,
et al., J. Organomet. Chem. 443 (1993) C11. (e) R. Reina, O.
Rossell, M. Seco, M. Font-Bardia, X. Solans, Organometallics
13 (1994) 2127. (f) P.M.N. Low, Y.K. Yan, H.S.O. Chan, T.S.
Andy Hor, J. Organomet. Chem. 454 (1993) 205. (g) O. Rossell,
M. Seco, G. Segale´s, J. Organomet. Chem. 503 (1995) 225. (h)
P.M.N. Low, A.L. Tan, T.S.A. Hor, Y-S. Wen, L-K. Liu,
Organometallics 15 (1996) 2595. (i) O. Rossell, M. Seco, G.
Segale´s, B.F.G. Johnson, P.J. Dyson, S.L. Ingham,
Organometallics 15 (1996) 884.
[2] M. Ferrer, R. Reina, O. Rossell, M. Seco, X. Solans, J. Chem.
Soc. Dalton Trans. (1991) 347.
[3] M. Ferrer, A. Julia`, O. Rossell, M. Seco, M.A. Pellinghelli, A.
Tiripicchio, Organometallics 16 (1997) 3715.
[4] (a) P. Braunstein, M. Knorr, M. Strampfer, et al., J. Chem. Soc.
Dalton Trans. (1994) 1533. (b) P. Braunstein, M. Knorr, M.
Strampfer, A. Tiripicchio, F. Ugozzoli, Organometallics 13
(1994) 3038.
[5] (a) P. Braunstein, M. Knorr, A. Tiripicchio, M. Tiripiccio-
Camellini, Inorg. Chem. 31 (1992) 3685. (b) A. Pons, O. Rossell,
M. Seco, A. Perales, Organometallics 14 (1995) 555.
[6] R.J. Puddephatt, Chem. Soc. Rev. 12 (1983) 99.
1
132.9–127.9 (m, Ph), 40.0 (dd, PCH2CH2CH2P, J(C–
3
2
P)=29, J(C–P)=17), 20.8 (t, PCH2CH2CH2P, J(C–
P)=7). Anal. Calc. for C65H46Au2Fe4O14P4: C 43.53, H
2.59. Found: C 43.75, H 2.71%.
3.5. Experimental conditions for the redistribution
reactions between [Fe2(v-CO)(CO)6(v-PPh2)]−
and[(ClAu)3(triphos)]
Solid [(ClAu)3(triphos)] (0.16 g, 0.12 mmol) and
TlBF4 (0.035 g, 0.12 mmol) were added to a THF
solution (40 ml) of [NEt4][Fe2(v-CO)(CO)6(v-PPh2)]
(0.075 g, 0.12 mmol) at r.t. After 30 min of stirring a
31P-NMR spectrum of the solution was carried out at
298 K and the data obtained were as follows: [{Fe2(v-
CO)(CO)6(v-PPh2)Au}(triphos)(AuCl)2] (5a) (major
product) l 130.6 (d, Fe2PPh2, 3J(PP)=24), 36.3 (d,
Fe2AuPPh2), 16.8 (s, ClAuPPh2), [{Fe2(v-CO)(CO)6(v-
PPh2)Au}2(triphosAuCl)] (5b) (minor product) l 131.0
3
(d, Fe2PPh2, J(PP)=24), 35.7 (d, Fe2AuPPh2), 16.8
(s, ClAuPPh2), [(ClAu)3(triphos)] (minor product) l
16.9 (s). No further changes in the spectrum were
observed on stirring longer.
[7] H. Schmidbaur, A. Wohlleben, F. Wagner, O. Orama, G. Hut-
tner, Chem. Ber. 110 (1977) 1748.
Solid TlBF4 (0.035 g, 0.12 mmol) and [NEt4][Fe2(v-
CO)(CO)6(v-PPh2)] (0.075 g, 0.12 mmol) were added to
the above reported solution. After 30 min of stirring a
31P-NMR spectrum of the solution was carried out at
298 K and the data obtained were as follows: [{Fe2(v-
CO)(CO)6(v-PPh2)Au}2(triphos)(AuCl)] (5b) (major
product), [{Fe2(v-CO)(CO)6(v-PPh2)Au}(triphos)(Au-
Cl)2] (5a) (minor product), [{Fe2(v-CO)(CO)6(v-PPh2)-
Au}3(triphos)] (5) (minor product) l 131.1 (d, Fe2PPh2,
3J(PP)=24), 35.5(d, Fe2AuPPh2), [(ClAu)3(triphos)]
(minor product) l 16.9 (s). No further changes in the
spectrum were observed on stirring longer.
[8] (a) M. Bardaj´ı, N.G. Connelly, M.C. Gimeno, J. Jime´nez, P.G.
Jones, A. Laguna, M. Laguna, J. Chem. Soc. Dalton Trans.
(1994) 1163. (b) E. Cerrada, M.C. Gimeno, J. Jime´nez, A.
Laguna, M. Laguna, Organometallics 13 (1994) 1470. (c) S.M.
Draper, C.E. Housecroft, J.E. Rees, M.S. Shongwe, B.S. Hag-
gerty, A.L. Rheingold, Organometallics 11 (1992) 2356.
[9] R.T. Baker, P.J. Krusic, J.C. Calabrese, D.C. Rose,
Organometallics 5 (1986) 1506.
[10] R. Reina, O. Rossell, M. Seco, J. Organomet. Chem. 398 (1990)
285.
[11] R. Uso´n, A. Laguna, Organomet. Synth. 3 (1986) 324.
[12] P. Cassoux, R. Dartiguepeyron, C. David, D. de Montauzon,
J.B. Tommasino, P.L. Fabre, Actual. Chim. 1 (1994) 49.
.