Synthesis of Co2Pt, Co2Pd and MoPd2 mixed-metal clusters with the P-N-P assembling ligands (Ph2P)2NH (dppa) and (Ph2P)2NMe (dppaMe). Crystal structure of [Co2Pt(μ

Article abstract of DOI:10.1016/S0022-328X(99)00355-1

Heterometallic triangular platinum-cobalt, palladium-cobalt and palladium-molybdenum clusters stabilized by one or two bridging diphosphine ligands such as Ph₂PNHPPh₂ (dppa) or (Ph₂P)₂NMe (dppaMe) or by mixed li

Full text of DOI:10.1016/S0022-328X(99)00355-1

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 588 (1999) 144–151
Synthesis of Co2Pt, Co2Pd and MoPd2 mixed-metal clusters with
the P–N–P assembling ligands (Ph2P)2NH (dppa) and
(Ph2P)2NMe (dppaMe). Crystal structure of
[Co2Pt(m3-CO)(CO)6(m-dppa)]ꢀ
Isolde Bachert a, Irene Bartusseck a, Pierre Braunstein a,*, Emmanuel Guillon a,
a
Jacky Rose´ , Guido Kickelbick b
a Laboratoire de Chimie de Coordination, UMR 7513 CNRS, Uni6ersite´ Louis Pasteur, F-67070 Strasbourg, Cedex, France
b Institut fu¨r Anorganische Chemie, Technische Uni6ersita¨t Wien, Getreidemarkt 9/153, A-1060 Wien, Austria
Received 20 October 1998
Abstract
Heterometallic triangular platinum–cobalt, palladium–cobalt and palladium–molybdenum clusters stabilized by one or two
bridging diphosphine ligands such as Ph2PNHPPh2 (dppa) or (Ph2P)2NMe (dppaMe) or by mixed ligand sets Ph2PCH2PPh2
(dppm)/dppa have been prepared with the objectives of comparing the stability and properties of the clusters as a function of the
short-bite diphosphine ligand used and of the metal carbonyl fragment they contain. Ligand redistribution reactions were
observed during the purification of [Co2Pd(m3-CO)(CO)4(m-dppa)(m-dppm)] (4) by column chromatography with the formation of
¸¹¹¹¹¹¹¹º
[Co2Pd(m3-CO)(CO)4(m-dppm)2] and the dinuclear complex [(OC)2Co(m-dppa)2PdCl] (5). The latter was independently prepared by
reaction of [Pd(dppa-P,P%)2](BF4)2 with Na[Co(CO)4]. Attempts to directly incorporate the ligand (Ph2P)2N(CH2)3Si(OMe)3
(dppaSi) into a cluster or to generate it by N-functionalization of coordinated dppa were unsuccessful, in contrast to results
obtained recently with related clusters. The crystal structure of [Co2Pt(m3-CO)(CO)6(m-dppa)] (1) has been determined by X-ray
diffraction. © 1999 Elsevier Science S.A. All rights reserved.
Keywords: Bimetallic; Clusters; Assembling ligands; Diphosphines
acidity of the NH proton versus the CH2 protons may
facilitate subsequent functionalization reactions that
1. Introduction
would require too drastic conditions in the case of
The short-bite ligand bis(diphenylphosphinoamine)
dppm. We have recently exploited this feature to pre-
(Ph2PNHPPh2, dppa) is receiving increasing attention
pare N-alkyl derivatives of dppa clusters, including
for assembling metal centres in bi- or polynuclear
metal complexes owing to both its isoelectronic rela-
substituents with a trialkoxysilyl group that could sub-
sequently be used for condensation reactions in a sol-
tionship with the more popular bis(diphenylphosphi-
gel process with the aim of incorporating metal
nomethane) ligand (Ph2PCH2PPh2, dppm) and the
clusters into a silica matrix in a covalent manner [1g,
increased reactivity of its N–H group compared with
2]. Here we report on the synthesis of Co2Pt, Co2Pd
that of the CH2 unit in dppm [1]. Thus, the greater
and MoPd2 mixed-metal clusters containing the dppa
ligand and our attempts towards N-derivatization.
Heterometallic triangular clusters containing two dppa
ligands or dppa and dppm (mixed ligand sets) have
been prepared by direct incorporation of the second
diphosphine ligand.
ꢀ PII of original article S0022-328X(98)01164-4.
* Corresponding author. Fax: +33-03-8841-6030.
E-mail address: braunst@chimie.u-strasbg.fr (P. Braunstein)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00355-1

I. Bachert et al. / Journal of Organometallic Chemistry 588 (1999) 144–151
145
Fig. 1. View of the structure of the two independent molecules of [Co2Pt(m3-CO)(CO)6(m-dppa)] (1).
2. Results and discussion
detailed view of one molecule with the atom numbering
scheme is given in Fig. 2. Selected bond distances and
angles for one molecule are given in Table 1. The
bonding parameters of the second independent
molecule are in most cases within the range of the
standard deviations of the first molecule and therefore
not listed.
The three metal atoms of one molecule form a trian-
gle and the Pt(10)–Co(12) bond is bridged by the dppa
ligand. The face of this triangle is capped by an unsym-
metrically bonded carbonyl group which has relatively
short distances to the two Co atoms [Co(11)–C(122)=
2.1. Platinum–cobalt clusters
By analogy with the carbonylmetalate-induced ring-
opening reactions observed with [PtCl2(dppm-P,P%)],
which led to a range of mixed-metal clusters [3], we
have reacted [PtCl2(dppa-P,P%)] with two equivalents of
Na[Co(CO)4] in THF and isolated in a 93% yield the
new cluster [Co2Pt(m3-CO)(CO)6(m-dppa)] (1) (Eq. (1)):
,
1.98(1), Co(12)–C(122)=1.89(1) A] and a rather long
(1)
,
distance to the Pt(10) atom (2.55(1) A). This situation is
similar to that of the related triangular cluster com-
pound [Co2Pt(m3-CO)(CO)7(PPh3)] which also shows
short Co–C bond distances to the m3-bridging carbonyl
,
group (1.88(1), 1.93(1) A) and a rather long Pt–C
Analytical and spectroscopic data are fully consistent
with the structure shown in Eq. (1), which was also
confirmed by an X-ray diffraction study (see below).
The IR spectrum in the w(CO) region contains absorp-
tions typical of terminal CO ligands as well as a band at
1772 cm−1, which corresponds to the bridging CO
ligand. The proton of the amino group of the coordi-
nated dppa ligand gives rise to a broad multiplet at l
6.31 in acetone-d6 because of coupling to the adjacent
phosphorus atoms. The 31P{1H}-NMR resonance for
the Pt-bound P atom appears at l 46.1, with typical
values of 1J(PPt)=3596 Hz and 2+3J(PP)=20 Hz.
The Co-bound P nucleus gives rise to a broad reso-
nance at l 73.1 owing to the quadrupolar effect of
cobalt. These values are consistent with those observed
in related clusters [2].
,
distance (2.57(1) A) [4a]. The coordination sphere
around the Pt(10) atom is ideal planar with a sum of
2.1.1. X-ray diffraction study of
[Co2Pt(v3-CO)(CO)6(v-dppa)] (1)
There are two independent molecules in the unit cell
and their molecular structures is shown in Fig. 1. A
Fig. 2. View of the structure of one molecule of [Co2Pt(m3-
CO)(CO)6(m-dppa)] (1).

146
I. Bachert et al. / Journal of Organometallic Chemistry 588 (1999) 144–151
the disappearance of the band at 2052 cm−1 in the
precursor, indicating that the Pt-bound CO ligand has
been displaced by dppa. The two protons of the amino
groups of the coordinated dppa ligands of 2 are equiv-
alent and give rise to a broad multiplet at l 6.34 ppm
in acetone-d6 because of coupling to the adjacent phos-
phorus atoms. The 31P{1H}-NMR resonances for the
Pt-bound P atoms appear at l 56.6, whereas the Co-
bound P nuclei give rise to a broad resonance at l 77.6
owing to the quadrupolar effect of cobalt. A detailed
analysis of this AA%BB% spin system (A=B=P) was
not possible owing to insufficient resolution. The
1J(PPt) value of 3917 Hz is larger than in 1, which
may reflect an increased electron density in 2. In a
similar manner, the dppa/dppm cluster [Co2Pt(m3-
CO)(CO)4(m-dppa)(m-dppm)] (3) was prepared by reac-
tion of 1 with dppm. This complex could not be
isolated pure in the solid-state, it was however fully
characterized in solution (see Section 3). Attempts to
coordinate the diphosphine ligands (Ph2P)2NMe (dp-
paMe) or (Ph2P)2N(CH2)3Si(OEt)3 (dppaSi) in a similar
manner were unsuccessful. With these two ligands, we
have previously observed that their incorporation into
a cluster is very sensitive to the nature of the latter [2].
The alternative approach of reacting [PtCl2(dppaSi-
P,P%)] with two equivalents of Na[Co(CO)4] was
unsuccessful.
Table 1
,
Selected bond lengths (A) and angles (°) for [Co2Pt(m3-CO)(CO)6(m-
dppa)] (1), molecule A
,
Bond lengths (A)
Pt(10)–C(100)
Pt(10)–P(100)
Pt(10)–Co(11)
Pt(10)–Co(12)
Co(11)–Co(12)
Pt(10)–C(122)
Co(11)–C(112)
Co(11)–C(110)
1.85(2)
Co(11)–C(111)
1.81(2)
1.98(1)
1.77(2)
1.80(2)
1.89(1)
2.175(3)
1.67(1)
1.699(9)
2.259(3) Co(11)–C(122)
2.531(2) Co(12)–C(120)
2.508(2) Co(12)–C(121)
2.531(2) Co(12)–C(122)
2.54(2)
1.75(2)
1.77(2)
Co(12)–P(102)
P(100)–N(101)
N(101)–P(102)
Bond angles (°)
Pt(10)–Co(11)–Co(12) 59.40(5) C(122)–Co(12)–P(102) 100.4(4)
Co(11)–Pt(10)–Co(12) 60.30(5) C(120)–Co(12)–Pt(10) 161.7(5)
Pt(10)–Co(12)–Co(11) 60.30(6) C(121)–Co(12)–Pt(10)
C(100)–Pt(10)–P(100) 101.6(4) C(122)–Co(12)–Pt(10)
Co(12)–Pt(10)–C(100) 165.7(4) P(102)–Co(12)–Pt(10)
P(100)–Pt(10)–Co(12) 92.68(9) N(101)–P(100)–Pt(10) 110.1(3)
C(100)–Pt(10)–Co(11) 105.5(4) P(100)–N(101)–P(102) 121.3(5)
Co(12)–Pt(10)–C(122) 44.0(3) N(101)–P(102)–Co(12) 112.6(4)
Co(11)–Pt(10)–C(122) 45.9(3) O(122)–C(122)–Co(12) 142(1)
C(112)–Co(11)–Co(12) 139.6(4) O(122)–C(122)–Co(11) 137(1)
C(110)–Co(11)–Co(12) 103.5(5) Co(12)–C(122)–Co(11) 81.6(5)
C(111)–Co(11)–Co(12) 98.6(4) O(122)–C(122)–Pt(10) 124(1)
C(122)–Co(11)–Co(12) 47.7(4) Co(12)–C(122)–Pt(10)
C(120)–Co(12)–P(102) 99.3(5) Co(11)–C(122)–Pt(10)
C(121)–Co(12)–P(102) 103.4(5)
87.3(5)
69.0(4)
94.8(1)
67.0(4)
66.7(4)
the angles of the ligands of 360°. The Co(12) atom has
a distorted trigonal bipyramidal coordination sphere
where the two terminal and the m3-bridging carbonyl
groups are in the equatorial plane and the P(102) atom
of the dppa ligand and the Co(11) atom are in the
axial positions.
(2)
,
The Co–Pt bond lengths of 2.508(2) and 2.531(2) A
are in the range observed for clusters with Co–Pt cores
[4]. The shorter bond is the one that is bridged by the
dppa ligand. The P–N–P angle is 121.3(5)°, similar to
that of the dppaMe ligands in the triangular cluster
[Pd2Co(CO)7(m-dppaMe)3](PF6) (121.0(4)°) [2]. The Pt–
We therefore tried to functionalize cluster 1 by react-
ing a THF solution with excess DBU or KH and then
with MeI. The 31P{1H}-NMR resonances of the func-
tionalized complex show a downfield shift compared
with that of 1 (ca. +20 ppm): the resonance for the
Co-bound P atom appears at l 97.7 and for the Pt-
bound P atom at l 68.1 (1J(PPt)=3619 Hz). However,
we encountered difficulties in reproducing this alkyla-
tion reaction, although this method was recently used
to prepare the cluster [Co2Pd(m3-CO)2(m-dppa-
Me)3](PF6) in a 71% yield from [Co2Pd(m3-CO)2(m-
dppa)3](PF6) [2]. Preliminary experiments were also
conducted to functionalize 1 by treating it in THF with
an excess of KH, followed by addition of
I(CH2)3Si(OMe)3. This did not lead to the expected
cluster and the brown powder obtained showed no
31P-NMR signal.
,
P distance of 2.259(3) A is in the range found in other
chelated Pt(dppa) complexes [1b]. The Co–P bond
,
length (2.175(3) A) is also comparable with other trian-
gular cluster compounds with bridging dppa ligand
[4c].
2.1.2. Reactions of [Co2Pt(v3-CO)(CO)6(v-dppa)] (1)
In order to evaluate the reactivity of this cluster
toward diphosphines that may further enhance the sta-
bility of the cluster, an equivalent of dppa was added
to a solution of 1 in THF (Eq. (2)). The expected
product [Co2Pt(m3-CO)(CO)4(m-dppa)2] (2) was ob-
tained as a red–brown powder. Its IR spectrum shows

I. Bachert et al. / Journal of Organometallic Chemistry 588 (1999) 144–151
147
2.2. Synthesis of palladium–cobalt and palladium–
molybdenum clusters
By analogy with procedures originally developed in
the dppm chemistry [5], we obtained the mixed-ligand
set cluster [Co2Pd(m3-CO)(CO)4(m-dppa)(m-dppm)] (4)
by reacting [PdCl2(dppm-P,P%)] with two equivalents
of Na[Co(CO)4] in THF at −30°C, followed by addi-
tion of one equivalent of dppa (Eq. (3)). The likely
intermediate [Co2Pd(m3-CO)(CO)6(m-dppm)] could not
be isolated [4].
(4)
(5)
In order to evaluate the influence of the metal car-
bonyl fragment in this chemistry, we reacted
[Pd2Cl2(m-dppa)2] with Na[MoCp(CO)3] and obtained
the cluster [MoPd2ClCp(m3-CO)2(m-dppa)2] (6), as an-
ticipated on the basis of our previous results with
dppm as an assembling ligand [8]. Although it could
not be isolated pure in the solid-state, its spectroscopic
data in solution are fully consistent with the structure
shown in Eq. (6).
(3)
Complex
4
was characterized in solution by
31P{1H}-NMR spectroscopy but could not be isolated
pure in the solid-state (see Section 3). During at-
tempts of purification by column chromatography,
(6)
formatio¸n¹¹¹¹¹¹º
of [Co2Pd(m3-CO)(CO)4(m-dppm)2] and
[(OC)2Co(m-dppa)2PdCl] (5) was observed (Eq. (4)).
The former results from ligand redistribution reactions
and was identified by comparison of its spectroscopic
data with the literature [5]. By analogy with its dppm
analogue [3c], complex 5 was independently prepared
by reaction of [Pd(dppa-P,P%)2](BF4)2 with a small ex-
cess of Na[Co(CO)4] in THF (Eq. (5)). This new pur-
ple dinuclear complex was characterized by
31P{1H}-NMR spectroscopy (AA%XX% spin system)
where the resonances for the Pd-bound P atoms ap-
pear at l 63.5 and for the Co-bound P atoms at l
82.0, respectively. The former value is downfield
shifted when compared with that of l 58.3 found for
the homodinuclear complex [Pd2Cl2(m-dppa)2] [6]. We
have pre¸vi¹ou¹s¹ly¹¹iso¹lºated the analogous dppm complex
[(OC)2Co(m-dppm)2PdCl] [3c] as well as the related 32-
electron Pd–Mn complex [(OC)3M¸n(¹m¹-d¹p¹p¹m¹)2¹PºdCl]
from the reaction of [Pd2Cl2(m-dppm)2] with Na[Mn-
(CO)5] [7].
Functionalization of this cluster by reaction with
KH followed by the addition of MeI or EtI afforded
[MoPd2ClCp(m3-CO)2(m-dppaMe)2] (7) or [MoPd2Cl-
Cp(m3-CO)2(m-dppaEt)2] (8), respectively. However, re-
action with KH and I(CH2)3Si(OMe)3 did not lead to
the desired N,N-derivatized cluster. This is somewhat
surprising since [CoPd2(m3-CO)2{m-(Ph2P)2(CH2)3Si-
(OMe)3}3](PF6) (9) has been obtained by this method
from [CoPd2(m3-CO)2(m-dppa)3](PF6) [2]. We have
however noted that the outcome of such alkylation
reactions very much depends upon the nature of the
precursor cluster and direct incorporation of the lig-
and (Ph2P)2N(CH2)3Si(OEt)3 (dppaSi) represents an in-
teresting alternative [2].

148
I. Bachert et al. / Journal of Organometallic Chemistry 588 (1999) 144–151
[PtCl2(cod)] [14] and [Pd(dppa-P,P%)2](BF4)2 [15] were
prepared according to literature methods. Solutions of
Na[Co(CO)4] and Na[MoCp(CO)3] · 2DME were pre-
pared according to the literature [16].
3.2.1. [PdCl2(dppa-P,P%)]
A sample of dppa (0.770 g, 2.000 mmol) was dis-
solved in CH2Cl2 (30 cm3) and added to a CH2Cl2 (30
cm3) solution of [PdCl2(cod)] (0.571 g, 2.000 mmol).
The product immediately precipitated as a colourless
solid and stirring was maintained for 30 min. After
filtration the solid was washed with Et2O and n-hexane.
Yield: 1.029 g (91%). The isolated complex was insolu-
ble in organic solvents and was characterized only by
elemental analysis. (Found: C, 51.77; H, 3.41; N, 2.45.
C24H21NP2Cl2Pd requires C, 51.23; H, 3.76; N, 2.49%).
Another possible access to [MoPd2ClCp(m3-CO)2(m-
dppaSi)2] could have been the reaction between
[Pd2Cl2(m-dppaSi)2] and Na[MoCp(CO)3]. However,
this approach was not successful.
Our results provide an easy entry into mixed-metal
clusters containing one or two dppa ligands. Systems
with different bridging ligands (dppa and dppm) in
well-defined positions have also been prepared. The
synthetic methods employed explain the regioselectivity
with which incorporation of the diphosphine ligands
occurs.
3.2.2. [PdCl2(dppaSi-P,P%)]
The procedure used was similar to that described for
[PdCl2(dppa-P,P%)], using [PdCl2(cod)] (0.571 g, 2.000
mmol) and dppaSi (1.178 g, 2.000 mmol). Yield: 1.169
g
(76%). (Found: C, 51.81; H, 5.34; N, 2.02.
C33H44NO3P2SiCl2Pd requires C, 51.50; H, 5.72; N,
1.82%). NMR (CDCl3): 1H, l 7.91–7.51 (m, 20H,
3
aromatic), 3.57 (q, 6H, J=3 Hz, OCH2), 3.02 (m, 2H,
3
NCH2), 1.25 (m, 2H, NCH2CH2), 1.02 (t, 9H, J=3
Hz, OCH2CH3), 0.19 (t, 2H, 3J=3 Hz,
NCH2CH2CH2Si); 31P-{1H}, l 30.77 (s, 2P“Pd).
3. Experimental
3.1. Reagents and physical measurements
3.2.3. [PtCl2(dppaSi-P,P%)]
All reactions were performed in Schlenk-type flasks
under purified nitrogen. Solvents were dried and dis-
tilled under nitrogen by conventional methods. Nitro-
gen was passed through BASF R3-11 catalyst and
molecular sieve columns to remove residual oxygen and
water. IR spectra were recorded on a Bruker IFS66
(4000–400 cm−1) spectrometer; samples were prepared
The procedure used was similar to that described for
[PdCl2(dppa-P,P%)], using [PtCl2(cod)] (0.740 g, 2.000
mmol) and dppaSi (1.178 g, 2.000 mmol). Yield: 1.374
g
(80%). (Found: C, 46.04; H, 5.06; N, 1.65.
C33H44NO3P2SiCl2Pt requires C, 46.15; H, 5.13; N,
1.63%). NMR (CDCl3): 1H, l 7.91–7.51 (m, 20H,
3
aromatic), 3.59 (q, 6H, J=3 Hz, OCH2), 2.91 (m, 2H,
1
3
as KBr pellets or solutions using CaF2 cells. The H-
NCH2), 1.22 (m, 2H, NCH2CH2), 1.04 (t, 9H, J=3
and 31P{1H}-NMR spectra were recorded at 300.13 and
121.5 MHz, respectively, on an FT Bruker AC 300
Hz, OCH2CH3), 0.19 (t, 2H, 3J=3 Hz,
NCH2CH2CH2Si); 31P-{1H},
1J(PPt)=3293 Hz).
l 16.28 (s, 2P“Pt,
1
instrument. The H- and 31P- shifts are given relative to
external SiMe4 and H3PO4, respectively. The 31P{1H}-
NMR resonances for the Co-bound P nuclei generally
give rise to a broad resonance owing to the quadrupo-
lar effect of cobalt. Elemental C, H and N analyses
were performed by the Service de microanalyses (Uni-
versite´ Louis Pasteur, Strasbourg).
3.2.4. [Co2Pt(v3-CO)(CO)6(v-dppa)] (1)
A filtered solution of Na[Co(CO)4] (0.1 M in THF,
6.6 cm3) was added to a suspension of [PtCl2(dppa-
P,P%)] (0.216 g, 0.332 mmol) in THF (50 cm3). The
mixture was heated (40°C) for 3 h after which time its
color had changed from yellow–brown to red–brown
and a white precipitate had formed. After filtration the
solvent was removed in vacuo and the residue was then
extracted with CH2Cl2 and filtered on a Celite-padded
filter funnel. The filtered solution was concentrated to
ca. 30 cm3 and the addition of n-hexane afforded a
red–brown microcrystalline powder of 1. Red single
crystals suitable for X-ray diffraction were obtained by
layering a THF solution with n-hexane. Yield: 0.352 g
3.2. Synthesis
The ligands Ph2PCH2PPh2 (dppm) [9], Ph2PNHPPh2
(dppa) [6] and (Ph2P)2NCH2CH2CH2Si(OEt)3 (dppaSi)
[1g] were prepared according to the literature. The
complexes [PtCl2(dppm-P,P%)] · C6H6 [10], [PdCl2-
(dppm-P,P%)] [11], [PtCl2(dppa-P,P%)] [12], [Pd2Cl2(m-
dppa)2] [6], [Pd2Cl2(m-dppaSi)2] [1g], [PdCl2(cod)] [13],

I. Bachert et al. / Journal of Organometallic Chemistry 588 (1999) 144–151
149
(93%). (Found: C, 41.34; H, 2.30; N, 1.45.
C31H21Co2NO7P2Pt requires C, 41.63; H, 2.37; N,
1.57%). IR (THF): w(CO) 2052s, 2033s, 2016s; 1995sh,
1985sh, 1967vs–br; 1887vs–br and 1772m cm−1. IR
(KBr): w(CO) 2057s, 2017s, 1993s, 1980s–sh and 1772w
Elution with a mixture of hexane (75%) and toluene
(25%) gave first a pale yellow solution of unreacted
compounds. Elution with a mixture of hexane (25%)
and toluene (75%) afforded a light purple solution of
[Co2Pd(m3-CO)(CO)4(m-dppm)2] [5a] characterized by
IR and 31P{1H}-NMR spectroscopics methods. Elution
with pure toluene afforded a dark purple solution of 5
characterized by IR and 31P{1H}-NMR spectroscopic
methods. Further elution with THF afforded a small
amount of a mixture of 4 and 5. Some dark purple
material remained on top of the column that could not
be eluted with THF or CH2Cl2.
1
cm−1. NMR (acetone-d6): H, l 7.37–7.19 (m, 20H,
aromatic), 6.31 (m, 1H, NH); 31P-{1H}, l 73.1 (br,
P“Co), 46.1 (d, P“Pt, 1J(PPt)=3596 Hz,
2+3J(PP)=20 Hz).
3.2.5. [Co2Pt(v3-CO)(CO)4(v-dppa)2] (2)
Upon addition of dppa (0.070 g, 0.182 mmol) to a
solution of [Co2Pt(CO)7(m-dppa)] (1) (0.163 g, 0.182
mmol) in THF (20 cm3) at room temperature (r.t.), gas
evolution was observed, indicating that a reaction was
occuring. The solvent was removed in vacuo and the
solid was washed with toluene (10 cm3) and n-hexane
(10 cm3), affording a red–brown powder (0.085 g, 38%).
(Found: C, 51.83; H, 3.31; N, 2.43. C53H42Co2N2O5P4Pt
requires C, 52.00; H, 3.43; N, 2.29%). IR (THF): w(CO)
1998s, 1967ms, 1950s and 1886s cm−1. NMR (acetone-
Complex 4 could not be isolated in pure form and was
characterized in solution by its 31P{1H}-NMR spectrum
(acetone-d6): l 78.7 (br, m, P“Codppa), 48.9 (m, P“
Pddppa), 27.55 (br, m, P“Codppm), −13.7 (d, P“
2
Pddppm, J(PP)=34 Hz).
3.2.8. [(OC)2Co¸(v¹-d¹p¹p¹a)¹2Pºd Cl] (5)
A filtered solution of Na[Co(CO)4] (0.1 M in THF,
2.8 cm3) and [Pd(dppa-P,P%)2](BF4)2 (0.279 g, 0.266
mmol) in THF (20 cm3) was stirred for 2 h at −30°C.
The color of the mixture rapidly turned from light
yellow to brown. After this time LiCl (0.011 g, 0.266
mmol) was added. The solvent was evaporated to dry-
ness under reduced pressure, the residue was extracted
with dichloromethane (20 cm3) and the solution was
filtered through a Celite-padded filter funnel. The sol-
vent was removed in vacuo and the residue was recrys-
tallized from a mixture of THF (15 cm3) and pentane
(60 cm3) at −20°C to afford green–brown microcrys-
talline powder of (5 · THF) (0.155 g, 53% based on Pd).
(Found: C, 58.37; H, 4.33; N, 2.58. C50H42PdN2-
O2P4ClCo · THF requires C, 58.98; H, 4.58; N, 2.55%).
IR (THF): w(CO) 1959vs and 1895s–br cm−1. NMR
1
d6): H, l 7.60–6.90 (m, 40 H, aromatic), 6.34 (br–m, 2
H, NH); 31P-{1H}, l 77.6 (br, 2 P“Co), 56.6 (br, 2
1
P“Pt, J(PPt)=3917 Hz).
3.2.6. [Co2Pt(v3-CO)(CO)4(v-dppa)(v-dppm)] (3)
This complex was prepared following a similar proce-
dure to that for complex 2, but starting from
[Co2Pt(CO)7(m-dppa)] (1) (0.500 g, 0.560 mmol) and
dppm (0.216 g, 0.560 mmol). However, it could not be
isolated in pure form and was characterized in solution
by its IR (THF): w(CO) 1997s, 1967s–br, 1950vs and
1885s cm−1, and its 31P{1H}-NMR (acetone-d6): l 76.7
1
(br, P“Codppa), 54.7 (m, br, P“Ptdppa, J(PPt)=3973
1
Hz), 26.5 (m, br, P“Codppm), 4.0 (m, br, P“Ptdppm
,
(acetone-d6): H, l 7.78–7.24 (m, 40H, aromatic), 6.29
1J(PPt)=3584 Hz). Alternatively, complex (3) may be
obtained by reaction of [Co2Pt(m3-CO)(CO)6(m-dppm)]
(0.500 g, 0.560 mmol) with dppa (0.216 g, 0.560 mmol)
under similar conditions.
(br, 2H, NH), 3.63 and 1.80 (THF signals); 31P-{1H}, l
82.0 (br, P“Co), 63.5 (t, P“Pd, N=ꢀJ(PAPX)+
J(PAPX%)ꢀ=116 Hz).
3.2.9. [MoPd2ClCp(v3-CO)2(v-dppa)2] (6)
3.2.7. [Co2Pd(v3-CO)(CO)4(v-dppa)(v-dppm)] (4)
A filtered solution of Na[MoCp(CO)3] · 2DME (0.1 M
in THF, 6.8 cm3) was added to a cooled (−78°C) and
stirred suspension of [Pd2Cl2(m-dppa)2] (0.360 g, 0.342
mmol) in 20 cm3 THF. The reaction was progressively
raised to ambient temperature while stirring was main-
tained for 2 h. The yellow–brown mixture was filtered
to remove insoluble NaCl. The filtrate was evaporated
to dryness and the residue extracted with CH2Cl2.
Precipitation with n-hexane yielded 6 (0.152 g, 62%)
contaminated with [Pd2Cl2(m-dppa)2] (25% by NMR).
Attemps to isolate pure 6 were unsuccessful. Data for 6:
IR (THF): w(CO) 1795mw and 1745s cm−1. NMR
A solution of Na[Co(CO)4] (0.1 M in THF, 5 cm3)
was added dropwise to a suspension of [PdCl2(dppm-
P,P%)] (0.140 g, 0.249 mmol) in THF (20 cm3) at
−30°C. The color of the suspension slowly turned from
light yellow to red. After this, solid dppa (0.096 g, 0.25
mmol) was added and the solution was further stirred
for 3 h. The reaction mixture was filtered on a Celite-
padded filter funnel to remove insoluble material, con-
taining
(THF/acetone-d6) of the reaction mixture revealed the
presence ¸o¹f¹¹4¹, ¹[ºCo2Pd(m3-CO)(CO)4(m-dppm)2] and
NaCl.
The
31P{1H}-NMR
spectrum
1
[(OC)2Co(m-dppa)2Pd Cl] (5). The solution was impreg-
nated on silica gel, evaporated to dryness and the
residue was chromatographed on a silica gel column.
(acetone-d6): H, l 7.48–7.19 (m, 40H, aromatic), 6.39
(m, 1H, NH), 6.18 (m, 1H, NH); 31P-{1H}, l 100.2 (m,
P“Mo), 45.1 (m, 2P“Pd), 42.5 (m, P“Pd).

150
I. Bachert et al. / Journal of Organometallic Chemistry 588 (1999) 144–151
Table 2
3.2.10. [MoPd2ClCp(v3-CO)2{v-(Ph2P)2NMe}2] (7)
To a solution of [MoPd2ClCp(m3-CO)2(m-dppa)2] (6)
(0.249 g, 0.201 mmol) in 20 cm3 THF was added an excess
of KH (2 mmol), gas evolution was observed, indicating
that a reaction was occuring. When gas evolution
stopped an excess of MeI (2 mmol) was added and stir-
ring was maintained for 3 h. After filtration the solvent
was removed in vacuo and the residue was then recrystal-
lized from CH2Cl2–n-pentane, affording a green–brown
microcrystalline powder of 7 (0.094 g, 37%). (Found: C,
54.36; H, 4.29; N, 1.96. C57H50Pd2N2O2P4-
ClMo requires C, 54.18; H, 3.96; N, 2.22%). IR (KBr):
w(CO) 1797m and 1747s cm−1. NMR (acetone-d6): 1H, l
7.56–7.14 (m, 40H, aromatic), 1.99 (br, 6H, CH3); 31P-
{1H}, l 118.3 (m, P“Mo, ꢀ2+3J(PP)ꢀ=27 Hz), 70.0 (m,
P“Pd), 67.2 (m, P“Pd), 64.9 (m, P“Pd). The other
coupling constants were not determined.
Crystal data and structure refinement for [Co2Pt(m3-CO)(CO)6(m-
dppa)] (1)
Empirical formula
Formula weight (g mol−1
Crystal system
Space group
Unit cell dimensions
C31H21Co2NO2P2Pt
894.38
Triclinic
)
(
P1
,
a (A)
10.9719(2)
13.9234(2)
21.8041(2)
87.249(1)
83.265(1)
74.873(1)
3192.80(8)
4
1.861
293(2)
5.545
Empirical
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
Dcalc. (g cm−3
T (K)
)
v (mm−1) (Mo–Ka)
Absorption correction
F(000)
1728
3.2.11. [MoPd2ClCp(v3-CO)2{v-(Ph2P)2NEt}2] (8)
This complex was obtained following a procedure sim-
ilar to that detailed for 7, using [Pd2MoClCp(m3-CO)2(m-
dppa)2] (6) (0.249 g, 0.201 mmol) and EtI (2 mmol).
Recrystallization of the product from CH2Cl2–n-hexane
led to the formation of a green–brown microcrystalline
Crystal size (mm)
q range (°)
Indices ranges
0.22×0.18×0.04
0.94–25.00
−115h515, −195k519,
−225l531
Reflections collected
Independent reflections
Refinement method
Goodness-of-fit on F2
Final R indices [I=2|(I)]
Weighting scheme
18181
11067 [Rint=0.0572]
Full-matrix least-squares on F2
0.982
R=0.0593, Rw=0.1130
w=1/[|2(F2o)+(0.0492*P)2] with
P=(max (F2o, 0)+2*F2o)/3
−2.436/2.303
powder containing
8 and [Pd2MoClCp(m3-CO)2(m-
dppa)2] (6). The two products could not be separated or
purified. Complex 8 was characterized by its 31P{1H}-
2+
NMR spectrum (acetone-d6): l 119.6 (m, P“Mo, ꢀ
Diff. Fourier peaks
−3
3J(PP)ꢀ=28 Hz), 71.8 (m, P“Pd), 65.9 (m, P“Pd),
63.7 (m, P“Pd). The other coupling constants were not
determined.
,
min./max. (e A
)
3.3. X-ray structure determination for
[Co2Pt(v3-CO)(CO)6(v-dppa)] (1)
free of charge from The Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ, UK (Fax: +44-1223-336-
033; e-mail: deposit@ccdc.ac.uk or www: http://
www.ccdc.cam.ac.uk).
Crystal data and experimental details are given in
Table 2. The X-ray data of the compound were collected
on a Siemens SMART CCD area detector diffractometer
using graphite monochromated Mo–Ka radiation (u=
Acknowledgements
,
0.71073 A), a nominal crystal-to-detector distance of 3.85
cm and 0.3° ꢀ-scan frames. Corrections for Lorentz po-
larization effects as well as an empirical adsorption cor-
rection with the program SADABS were applied [17]. The
structures were solved by direct methods (SHELXS86).
Refinement was performed by the full-matrix least-
squares method based on F2 (SHELXL93) with anisotropic
thermal parameters for all non-hydrogen atoms. All non-
hydrogen atoms were refined anisotropically and hydro-
gen atoms were included in idealized positions.
We are grateful to the Centre National de la Recherche
Scientifique (Paris), the Commission of the European
Communities (contract CHRX-CT93-0277) and the
Ministe`re des Affaires Etrange`res (Paris) (Amadeus Pro-
gramme between Strasbourg and Vienna) for financial
support and the Socrates/Erasmus programme (ICP 95-
UK-1002) for allowing I. Bartusseck from Aachen (Ger-
many) to spend 4 months in the Strasbourg Laboratory.
References
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the Cambridge Crystallographic Data Centre, CCDC
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