Neutral and cationic 1,4-diphospha-2-rhoda-3-thia-[4]-ferrocenophane

Article abstract of DOI:10.1016/S0022-328X(99)00293-4

A mixed bidentate ferrocenyl ligand Fe(η⁵-C₅Me₄P(S)Ph₂)(η ⁵-C₅Me₄PPh₂) (abbreviated {P,P=S}) was synthesised and used for complexation with [RhCl(CO)₂]₂. The neutral [4]-ferrocenophane {P,P=S}Rh(CO)Cl 2 and the unusual dimeric cationic species [{P,P=S}Rh(CO)(μ-Cl)(CO)Rh{P,P=S}]⁺ 3 were obtained and characterized by crystal structure analysis. During investigations on the catalytic properties of 2 in carbonylation, some aspects of its behavior towards iodomethane were elucidated.

Full text of DOI:10.1016/S0022-328X(99)00293-4

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 587 (1999) 104–112
Neutral and cationic
1,4-diphospha-2-rhoda-3-thia-[4]-ferrocenophane
Roland Broussier a,*, Myriam Laly a, Patrice Perron a, Bernard Gautheron a,
Ilya E. Nifant’ev a,b, Judith A.K. Howard c, Lyudmila G. Kuz’mina c,d, Philippe Kalck e
a Laboratoire de Synthe`se et d’Electrosynthe`se Organome´talliques associe´ au CNRS, UMR 5632, 6 boule6ard Gabriel, BP 138,
F-21004 Dijon Cedex, France
b Department of Chemistry, Moscow State Uni6ersity, 119899 Moscow, Russia
c Department of Chemistry, Uni6ersity of Durham, South Road, Durham DH1 3LE, UK
d N.S.Kursako6 Institute of General and Inorganic Chemistry, RAS, Leninskiiprosp. 31, 117907 Moscow, Russia
e Laboratoire de Catalyse,Chimie Fine et Polyme`res, Ecole Nationale Supe´rieure de Chimie, 118 route de Narbonne,
F-31077 Toulouse Cedex, France
Received 4 April 1999
Abstract
A mixed bidentate ferrocenyl ligand Fe(h5-C5Me4P(S)Ph2)(h5-C5Me4PPh2) (abbreviated {P,PꢀS}) was synthesised and used for
complexation with [RhCl(CO)2]2. The neutral [4]-ferrocenophane {P,PꢀS}Rh(CO)Cl 2 and the unusual dimeric cationic species
[{P,PꢀS}Rh(CO)(m-Cl)(CO)Rh{P,PꢀS}]+ 3 were obtained and characterized by crystal structure analysis. During investigations
on the catalytic properties of 2 in carbonylation, some aspects of its behavior towards iodomethane were elucidated. © 1999
Elsevier Science S.A. All rights reserved.
Keywords: Ferrocenophane; Heterobimetallic; Iron–rhodium; Oxidative addition
complexation due to their air-stability. They lead to
various species offering a great variety of properties.
For example, the rhodium derivatives are efficient cata-
lysts for olefin hydroformylation or hydrogenation [3].
Recent reports have highlighted the catalytic poten-
tial of diphosphinemonoxide and diphosphine mono-
sulfide ligands. Those are mixed-donor ligands, [P,PꢀE]
(E=O, S), which offer the opportunity to exhibit either
unidentate coordination or chelation, the latter forming
monomeric, mononuclear or dinuclear derivatives.
Among these ambivalent ligands the diphosphinesulfide
Ph2PCH2P(S)Ph2 promotes the rhodium-catalysed car-
bonylation of methanol [5].
In a previous paper [4] we reported the preparation
of several mixed-donor diphosphine ligands based on
the ferrocenyl moiety, for which the coordination chem-
istry has not yet been studied. We made the hypothesis
that the synthesis of the related rhodium derivatives
using diphosphinesulfide Ph2PC5Me4FeC5Me4P(S)Ph2
produces [4]-ferrocenophane. Beside the potential utility
of ferrocenyl-rhodium complexes for catalytic applica-
1. Introduction
Many of the transition metal centers that play an
important role in catalysis contain bidentate ligands in
their coordination sphere. The control of the reactivity
and the selectivity of the catalyst has been largely
improved during the last few years [1]. A particular
bidentate ligand can be used in order to tune the
electronic and steric properties of a given complex.
Casey recently developed the model of the natural bite
angle of a diphosphine to tentatively rationalize the
selectivities observed in the hydroformylation of alke-
nes with rhodium-diphosphine ligand, as a function of
the geometry imposed by the ligand [2]. Thus it was
attractive to develop a class of bidentate ligands in
which two cyclopentadienyl ligands with a coordinating
heteroatom group are linked in a metallocenic entity. In
this class of compounds, ferrocenyl compounds such as
dppf [3] or dppomf [4] are common ligands used for
* Corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00293-4

R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
105
tions, it was of interest to investigate the chemistry
and conformational behaviour of [4]-ferrocenophanes
which have remained largely unexplored [6].
when the reaction was repeated, it was not possible to
obtain a reproducible ratio of products presumably
owing to small variations in the reaction conditions
(ratio of reactants, concentrations, conditions of mix-
ing). In addition, when a dichloromethane solution of
2 and 3 was allowed to stand for a number of days,
the evolution of the 2/3 ratio was observed. It has
been shown previously that the coordination be-
haviour of rhodium(I) may be subject to change, de-
pending on the experimental conditions. Thus,
complexes formed by mixing [RhCl(CO)2]2 with
Ph2PCH2P(S)Ph2 (dppmS) in methanol are mononu-
clear RhCl(CO)dppmS, whereas neutral dimers
[RhCl(CO)dppmS]2 are isolated in dichloromethane
[5,10].
Complexes 2 and 3 are air-stable. Their very similar
spectral parameters do not allow clear differentiation
of their structures. Both complexes 2 and 3 involve
[P,S] chelation as indicated by the 31P-NMR and IR
data. In 31P-NMR the doublet at 34.0 ppm (1J=176
Hz) for 2 and 32.6 ppm (1J=180 Hz) for 3 are indica-
tive of a phosphorus–rhodium bonding interaction
(the free ligand l value is −24.8 ppm). In contrast
the l(PꢀS) at 43.2 ppm for 2 and 3, are close to, but
definitely distinct from, that of the free ligand (41.3
ppm). Rhodium complexation of the thiophosphoryl
ligand is also consistent with a lowering PꢀS stretching
frequency observed in the IR spectra (632 cm−1 for 2
and 3; 647 cm−1 for 1).
2. Result and discussion
2.1. Preparati6e results
The dissymetrical complex Fe(h5-C5Me4P(S)Ph2)(h5-
C5Me4PPh2) 1 containing simultaneously a phosphorus
(III) and a phosphorus (V) atom was previously pre-
pared by action of elementary sulfur on the 1,1%-
diphenylphosphinooctamethylferrocene. The absence
of any differentiation for the two initial phosphorus
sites leads to the formation of several products. After
chromatography of the mixture the dissymetric 1-
diphenylthiophosphino-1%-diphenylphosphinooc-
tamethylferrocene (1) was isolated in very low yield
(13%) [4].
In order to improve the yield, we have examined the
preparation of the ferrocenyl compound by reaction of
the two suitably substituted cyclopentadienyl salts,
C5Me4PPh2Li and C5Me4P(S)Ph2Li, on FeCl2.
The 1,2,3,4-tetramethylcyclopenta-1,3-diene was ob-
tained in four steps from butanone via 3,4-dimethyl-
hexane-2,5-diones and trimethylcyclopentenones [4].
The two last steps consist of the action of methyl-
lithium on trimethylcyclopentenones and the dehydra-
tion of the tetramethylcyclopentenol formed in the
presence of hydrochloric acid. This preparation is a
convenient alternative to the procedures generally de-
scribed in the literature [4,8].
Since the spectroscopic data alone could not allow
the nature of the complexes to be unequivocally as-
signed, X-ray structural investigations have been car-
ried out on complexes 2 and 3. Compound 2 is the
neutral [4]-ferrocenophane whereas 3 shows an un-
usual structure consisting of a dimeric cationic species
with two anionic counterparts (vide infra).
C5Me4HPPh2 was readily obtained by the successive
action of butyllithium and chlorodiphenylphosphine
on
tetramethylcyclopentadiene,
whereas
C5Me4HP(S)Ph2 required the supplementary addition
of elemental sulfur [9]. Suitable cyclopentadienyl salts,
C5Me4PPh2Li and C5Me4P(S)Ph2Li, were further ob-
tained by reaction of one equivalent of butyllithium.
Finally, successive additions of C5Me4P(S)Ph2Li and
C5Me4PPh2Li, at −78°C, to a suspension of FeCl2 in
THF led to the formation of the dissymetric species 1
(60%, Eq. (1)) with only a small amount of the sym-
metric ones (diphosphine and bis(phosphinesulfide)).
The structural studies indicate that 2 should be a
precursor to 3. In fact, compound 2, which was exclu-
sively obtained from the 1:1 reaction between 1 and
[RhCl(CO)2]2 in toluene instead of dichloromethane,
further reacts with [RhCl(CO)2]2 to yield cationic 3
with [RhCl2(CO)2]− as anion. The presence of
[RhCl2(CO)2]− in the anionic part greatly complicates
the IR spectra in the CO absorption. In addition, 3
associated with BF4− was prepared by treatment of 2
with AgBF4. Hence 2 shows a w(CꢀO) band at 1987
cm−1 and 3 presents a single w(CꢀO) band at 2000
cm−1 consistent with a pseudo-centrosymmetric ar-
rangement for the two CO ligands.
(1)
Dichloromethane solutions of 1 and [RhCl(CO)2]2
reacted immediately on mixing at room temperature
(r.t.) to produce a mixture of two products, 2 and 3,
which were separated by recrystallisation. However,

106
R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
2.2. Molecular structure
pseudo-torsional angles are 29.7° in the first molecule
and −26.0°, in the second one. Two Cp rings in the
ferrocene moieties of each molecule are almost parallel:
the corresponding dihedral angles are 2.5 and 3.3°.
The P(1) and P(3) atoms are displaced from the
least-squares plane of the corresponding Cp ring oppo-
Crystals of 2 contain two independent heteronuclear
(Rh, Fe) complex molecules (A and B) (Figs. 1 and 2)
and three CHCl3 solvent molecules. In each molecule,
rhodium atom is bonded to the S and P atoms of the
two functional substituents ꢁPPh2 and ꢁPPh2S attached
to different ferrocenyl cyclopentadiene rings, one chlo-
rine and one terminal CO ligand to give a square-pla-
nar arrangement typical of 16 electron Rh(I)
complexes. In the two independent molecules, the cor-
responding bond lengths and bond angles are equal
within experimental error. It is well known that, in
square-planar transition metal complexes containing
different ligands, the metal–ligand distances are
sensitive to the mutual arrangement of the ligands.
Baker et al. [5] have reported the structure of
RhCl(CO)(Ph2PCH2PSPh2), with the ligand mutual ar-
rangement similar to that observed in 2. The RhꢁS
,
site from Fe atom by −0.327 and 0.338 A, respectively
(P(1)ꢁC(1) and P(3)ꢁC(6%) bend off are 9.4 and 9.6°).
Inversely, P(2) and P(4) atoms are displaced by 0.304
,
and −0.268 A (P(2)ꢁC(6) and P(4)ꢁC(1%) bend off are
8.7 and 10.8°). Spatial hindrance within the portions of
the complex results in the reduction of the bond angles
between the bonds with ipso atoms of phenylsub-
stituents on phosphorus. Bond angles C(12)ꢁP(1)ꢁC(18)
and C(24%)ꢁP(3)ꢁC(30%) are reduced to 93.9(6) and
96.0(5)°. Intrachelate angles at P(1) (118.4(4)°),
P(2)(118.5(4)°, P(3) (117.1(4)°, and P(4) (118.1°) are
increased compared to the tetrahedral value.
One side of the Rh coordination plane is eclipsed by
a ferrocene fragment. The Rh and Fe atoms are sepa-
,
bond distances 2.435(3) and 2.420(3) A in 2 are
,
longer than the RhꢁS bond length in RhCl(CO)(Ph2-
rated by 4.364 and 4.366 A in molecules A and B,
respectively.
,
PCH2PSPh2) (2.403(2) A). The RhꢁC bond lengths with
,
the carbonyl group (in both molecules, 1.80(2) A) are
Crystals of 3 are composed of the tetraheteronuclear
(2Rh,2Fe) complex cation, the [RhCl2(CO)2]− complex
anion, the Cl− anion and toluene molecules in the ratio
of 1:0.5:0.5:2. In the molecule of the cation, a two-fold
axis passes through the bridging Cl(1) atom (Fig. 3).
The geometry of each moiety of the cation is similar
to that of 2. In each moiety, the rhodium atom is also
coordinated by the two functional substituents ꢁPPh2
and ꢁPPh2S attached to different ferrocenyl cyclopenta-
diene rings, a single bridging chlorine atom and one CO
ligand to give square-planar coordination. The coordi-
nation planes of the Rh atoms are tilted to one another
by 76.6°.
,
comparable within experimental error (1.826(8) A) and
the RhꢁP bond lengths (2.216(3) and 2.219(3) A) are
also consistent with that in RhCl(CO)(Ph2PCH2PSPh2)-
,
,
(2.220(2) A). At the same time, although the SꢀP bond
,
lengths (1.994(4) and 2.001(4) A) are comparable
,
(2.005(3) A), the RhꢁSꢁP angles (110.9(2) and
112.4(1)°) are significantly increased compared to 98.6°.
,
The RhꢁCl bond lengths of 2.395(3) and 2.375(3) A
have normal values for a terminal chlorine ligand in
Rh(I) complexes [11].
The ferrocene fragments adopt a staggered confor-
mation in both molecules. The PꢁC(Cp)···C(Cp)ꢁP
Fig. 1. The molecular structure of 2A and atom numbering scheme.

R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
107
Fig. 2. The molecular structure of 2B and atom numbering scheme.
metal complexes containing the MꢁSꢀPR3 fragment
The occurrence of one bridging ligand Cl(1) between
the two Rh atoms is a peculiar feature of the structure.
,
[12] these values vary within the range of 1.99–2.04 A
,
and 102.5–116.6° with the mean values 2.016 A and
,
The Rh(1)ꢁCl(1) bond length is 2.435(2) A, the
108.8° exactly corresponding to those observed in 3.
The ferrocenyl has an almost ideal staggered confor-
mation, the P(1)ꢁC(1)···C(6)ꢁP(2) pseudo-torsional an-
gle being equal to 28.5°. The two Cp rings are nearly
parallel, and the dihedral angle between them is 4.5°.
The P(1) atom attached to the first Cp ring (C(1)···C(5))
Rh(1)Cl(1)Rh(1A) bond angle (87.86(9)°) is less than
90°. The difference is small but significant. The decrease
in the angle found cannot be explained by steric hin-
drance in the complex because no short interatomic
contacts between the two parts of the complex are
observed. It can probably be explained by a weak
secondary interaction between the Rh atoms. The cor-
,
is displaced from its least squares plane by −0.289 A
(P(1)ꢁC(1) bend off is 8.7°), whereas the displacement
,
responding Rh···Rh distance is 3.378 A.
of P(2) attached to the second Cp ring(C(6)ꢁC(10)) is
The Cambridge Crystallographic Database contains
only one example of a binuclear Rh compound where
two Rh atoms are combined through only one bridging
ligand Cl with the structure (CO)2ClRh(m-
Cl)Rh(CO)(Me4-phoran) [11]. In this neutral molecule,
,
0.265 A (P(2)ꢁC(6) bend off is 8.4°). Internal stress in 3
resembles that in 2. The bond angle C(19)ꢁP(1)ꢁC(25)
are reduced to 97.8(3)°. The intrachelate angles
(116.1(3)° at P(1) and 118.3(3)° at P(2)) are increased
compared to tetrahedral values. At the same time, the
angle at the sulfur atom has a normal value.
,
the RhꢁCl bond lengths 2.454 and 2.372 A are different
,
but their mean value (2.413 A) is close to the value
For each half of the cation, one side of the Rh
coordination plane is screened by the ferrocenyl frag-
found in 3. The angle at bridging Cl atom (89.4°) is
close to 90° than in our case and the Rh···Rh distance
,
ment (Fe···Rh distance is 4.331 A). The other side of
,
,
is some what longer 3.393 A (3.378 A for 3). The
difference in the Rh···Rh distance for these two struc-
tures is significant and can result from a weaker
Rh···Rh interaction in the case of the neutral complex
as compared to the present cationic species.
the Rh coordination plane is significantly eclipsed by
the phenyl rings at P(1) and P(1a) atoms. Although
these phenyl rings can rotate around PꢁC bonds in
some range, the space between the phenyl rings is of
rather restricted size. This fact may be important for
the specific catalytic activity of the compound.
The RhꢁS, RhꢁC(43) and RhꢁP(1) bond distances
,
are equal to 2.422(2), 1.833(8) and 2.241(2) A, respec-
The Rh(CO)2Cl2− anion exhibits an usual cis configu-
ration with expected metric parameters [13].
tively. The RhꢁS and RhꢁC bond distances are com-
parable, respectively with those in 2, whereas the RhꢁP
bond length is longer than those in 2 (2,216(3) and
,
2,219(3) A); this lenghtening may be considered as a
significant one caused by the ionic nature of the
complex.
2.3. Reacti6ity with iodomethane
The oxidative addition of iodomethane is often ex-
amined for rhodium(I) complexes because it represents
a good test for evaluating the nucleophilicity of the
,
The S(1)ꢁP(2) bond length is 2.010(3) A and the
Rh(1)ꢁS(1)ꢁP(2) angle is 108.12(9)°. In other transition

108
R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
of the cationic part of 5 has been established by the
observation of the NMR data. 31P-NMR spectrum
shows two singlets at 38.8 and 22.7 ppm whereas
1H-NMR shows a doublet at 3.24 ppm indicating the
decoordination of the rhodium fragment and formation
of a methyl-phosphonium salt. A series of infrared
spectra recorded during and after the reaction of 4 with
MeI diplays an evolution of the eliminated rhodium
fragment, initially formulated as [Rh2(CO)2I4]2−
(w(CꢀO) 2058 cm−1; litt: 2058 (KBr)[16]). This anion is
unstable in solution and forms [Rh2(CO)2I2]− whose
infrared absorption frequencies are observed at 2059
and 1988 cm−1. The structure of 5 is supported by the
spectroscopic identification of the product of the direct
reaction of methyl iodide on the ferrocenyl precursor 1.
metal centres. Moreover, this reaction is the rate-deter-
mining step for methanol carbonylation to acetic acid
catalysed by [RhI2(CO)2]− [5,14]. As the complex 2
presents some similarities with the procatalyst pub-
lished recently by Baker et al. [5] containing a thiophos-
phine ligand, we examined the reactivity of 2 and 3 with
CH3I. In addition it was interesting to observe how the
ferrocenyl fragment, which in 2 eclipses the rhodium
coordination plane, can move to allow the reaction
with CH3I.
The reaction of methyl iodide with
2
in
dichloromethane solution results in the quantitative
formation of the iodo-substituted rhodium complex 4.
The identity of the reaction products has been estab-
lished by X-ray structure analysis for 4 [15] and by
1H-NMR (sealed tube) for the byproduct CH3Cl. Com-
pund 4 is stable at r.t. but reacts with an excess of MeI
(neat or in concentrated solution) to give the ferrocenic
compound 5 of formula [Fe(h5-C5Me4P(S)Ph2)(h5-
C5Me4PPh2Me)]+ for the cationic part, involving the
decomposition of the bimetallic species 4. The structure
Fig. 3. The molecular structure of 3 and atom numbering scheme.

R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
109
Scheme 1.
It is widely accepted that iodomethane reacts with
square planar rhodium(I) complexes by a stepwise
mechanism: a classical S2N attack at the carbon atom
followed by coordination of the resulting iodide anion
[17]. A nucleophilic attack by 2 on iodomethane
would lead to the intermediate shown in Scheme 1,
with a five-coordinate rhodium centre. The coordina-
tion of iodide to this complex is hindered by the
ferrocenic portion of the molecule. Instead, it appears
that reductive elimination of chloromethane occurs,
either by a concerted process on attack of I− or by a
stepwise process with the resulting vacant site sta-
bilised by coordination of solvent. Compound 4 is the
expected thermodynamic product given that CꢁCl
bonds are stronger than CꢁI bonds (DHf= −81.9 kJ
mol−1 (MeCl), −12.3 kJ mol−1 (MeI)) [18] and that
RhꢁI bonds would be expected to be at least as
strong as, if not stronger than, RhꢁCl bonds. A sim-
ple substitution of chloride by iodide present in the
iodomethane, due to hydrolysis or photolysis seems
unlikely given that the near-quantitative isolated yield
of 4. Nor is there any evidence that the complete
oxidative addition process ever occurs. Compound 5
could form either by the migration of a methyl group
from rhodium to phosphorus [19], or by the direct
quaternisation of the phosphine group while it has
been momentarily displaced from the coordination
sphere of rhodium.
These reactivity studies show that complex 2 can-
not be a precursor to an active species for the car-
bonylation of methanol like the complex of Baker et
al. We are currently investigating the reactivity of
complexes 2 and 3, but in reactions other than the
methanol carbonylation.
3. Experimental
3.1. General considerations
The tetramethylcyclopentadiene was prepared by re-
acting a mixture of trimethylcyclopent-2-enone [7]
with MeLi followed by dehydration of intermediate
alcohol by simple ice-acidified water hydrolysis and
was isolated as the C2 isomer [8f].
The phosphine C5Me4HPPh2 was prepared follow-
ing
a
method similar to the synthesis of
C5Me3H2PPh2 [7] and C5Me4HP(S)Ph2 following [9].
All manipulations were performed under argon using
standard Schlenk tube techniques.

110
R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
3.2. Preparation of 1
(b) 2 (0.029 mmol, 25 mg) was dissolved in 15 ml of
CH2Cl2. To this orange solution was added a solution
of AgBF4 (0.015 mmol, 3 mg) in 3 ml of methanol.
After 2 h of stirring, the solvent was removed under
reduced pressure, giving a red powder. We obtained 3
quantitatively with BF4− as an anion. IR (CH2Cl2,
cm−1): w(CO)2000.
A solution of C5Me4HP(S)Ph2 (2.19 g, 6.5 mmol) in
20 ml of THF was treated with BuLi (7.2 mmol) at
−40°C over 30 min. Stirring was continued at r.t. for 3
h. The solution, now containing [C5Me4P(S)Ph2Li], was
added dropwise, at −78°C, to a suspension of FeCl2
(0.93g,6.5 mmol) in 15 ml of THF. Immediatly after the
end of the addition, a solution of [C5Me4PPh2Li] (2.2g,
6.5 mmol) in 40 ml of THF at −78°C was also added.
The cold bath was then removed and the mixture was
allowed to warm to r.t., and stirred for 18 h.
The mixture was then treated with diethyl ether and
the combined organic extracts were washed with water
before being dried with MgSO4. After filtration, the
solvent was removed and the brown residue was chro-
matographied on a silica column with 2:1 toluene–hex-
ane as eluent.
Three successive orange fractions were observed: The
firstone contained dppomf, the second contained the
expected product and the last one the disulfured com-
pound. The solvent was removed from the second
fraction and gave 1 as a yellow powder (60% yield).
The analytical and spectroscopic data of the isolated
product were identical to those described in Ref. [4].
3.5. Reaction of 1 with 0.5 equi6alent of [RhCl(CO)2]2
in CH2Cl2
A solution of 1.3 mmol (0.5 g) of [RhCl(CO)2]2 in 10
ml of CH2Cl2 was added, at r.t., to a solution of 2.6
mmol (1.8 g) of 1 in 30ml of CH2Cl2. After 1 h of
stirring, the solvent was removed in vacuo and the
mixture was purified in air by recrystallization in
toluene–CH2Cl2. This purification gave red crystals of
3 (40%) suitable for X-ray analysis and a solution that,
after evaporation, yielded to an orange–red powder of
2 (60%). Anal. Calc. for C87H88Cl2.5Fe2O3P4Rh2.5S2,
2(C7H8), 5 H2O: C, 57.74; H, 5.42; S, 3.05. Found: C,
57.78; H, 5.00; S, 3.04.
3.6. Reaction of 2 with MeI
3.6.1. Preparation of 4
1.5 ml of a solution of iodomethane in CH2Cl2 (0.023
M) was added to a solution of (0.23 mmol, 200 mg) 2
in 15 ml of CH2Cl2. After 2 h of stirring, the solvent
was evaporated to dryness: a brown, pure, powder was
so obtained. IR (CH2Cl2,cm−1): w(CO) 1981.3. 31P-
NMR(CDCl3): 32.11 (d, JPꢁRh=176 Hz), 42.13 (s).
1H-NMR (CDCl3): l 1.54 (6H, s), l 1.64 (6H, s), l 1.70
(12H, s), l7.20 (m), l 7.38 (m), l 7.64 (m).
3.3. Preparation of 2
A solution of 0.13 mmol (50 mg) of [RhCl(CO)2]2 in
5 ml of toluene was added, at r.t., to a solution of 0.26
mmol (180 mg) of 1 in 25 ml of toluene. After 2 h of
stirring, a precipitate was observed. After filtration, an
orange powder was obtained. The yield was essentially
quantitative.
3.6.2. Preparation of 5 (neat iodomethane)
This powder was recrystallised from a mixture of
toluene and chloroform and gave orange crystals suit-
able for crystal structure determination. Anal. Calc. for
C43H44ClFeOP2RhS·CHCl3: C, 52.48; H, 4.47; Rh,
10.45. Found: C, 52.68; H, 4.70; Rh,9.73. IR (CH2Cl2,
Compound 2 (0.43 mmol, 370 mg) was dissolved in 5
ml of iodomethane. The orange solution became dark
red immediately. The solvent was removed under re-
duced pressure and a red powder was obtained. Anal.
Calc. for C43H47P2S1Fe1I1: C, 61.46; H, 5.59;S, 3.81.
Found: C, 61.22; H, 6.23; S, 3.40. 31P-NMR (CDCl3):
38.78 (s), 22.81 (s).1H-NMR (CDCl3): l 1.41 (6H, s), l
1.57(6H, s), l 1.70 (6H, s), l 1.85 (6H, s), l 3.26 (3H,
d, JPꢁH=13.4 Hz), l 7.44 (m).
cm−1): w(CO)1986.7. 31P-NMR (CDCl3): 33.97 (d,
1
JPꢁRh=176 Hz), 43.16 (s). H-NMR (CDCl3): l 1.60
(6H, s), l 1.69 (6H, s), l 1.71 (6H, s), l 1.72 (6H, s), l
7.24 (m), l 7.40 (m), l 7.46 (m), l 7.68 (m).
3.4. Preparation of 3
3.7. X-ray crystallography
(a)
A solution of 0.025 mmol (100 mg) of
Compound 2 consists of two independent complex
molecules and three partially rotationally disordered
solvent molecules. The refined position of the solvent
molecules is not completely occupied. Two of the
molecules (C(1%%)HCl3 and C(2%%)CHCl3) have a site
occupation factor equal to 0.8 and the third molecule
(C(3%%)HCl3) has a factor equal to 0.4. In the structure,
the highest peaks of residual electron density are lo-
cated in the vicinity of these solvent molecules.
[RhCl(CO)2]2 in 2 ml of toluene was added to a mixture
of 0.05 mmol (450 mg) of 2 in 30 ml of toluene. After
2 h of stirring, a precipitate was formed which was
isolated by filtration and was obtained as a red powder
(quantitative yield). 31P-NMR (CDCl3): 32.61 (d,
1
J
PꢁRh=180 Hz), 43.23 (s). H-NMR (CDCl3): l 1.63
(6H, s), l 1.77(6H, s), l 1.80 (6H, s), l 1.81 (6H, s), l
6.96 (m),l 7.26 (m), l 7.39 (m), l 7.53 (m), l 7.71(m).

R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
111
are disordered in the space. Such a suggestion is sup-
ported by a number of highest peaks of residual elec-
tron density in the vicinity of chlorine and carbonyl
ligands anion. The water molecules are, probably, hy-
drogen-bonded to the Cl− anion and fix the anion in
its position. However, we failed to successfully refine
the electron density peaks identified as oxygen which
are located at a suitable distance from Cl−.
The structure of 3 is composed of a complex tetranu-
clear cation, two types of anions and a solvent toluene
molecule. The cation and both anions occupy special
positions on the two-fold axes, the toluene molecule is
in a general position. The anions share the same posi-
tion with the half site occupation factor (s.o.f. is 0.25
for Rh(2) and Cl(3) and 0.5 for Cl and CO ligands).
Since the size of the chloro anion is significantly smaller
than that of [RhCl2(CO)2]− one can expect that the
empty space around Cl− anion is filled by a small
molecules. Most likely these are water molecules, which
The structures were solved and refined using
SHELXS86 [20] and SHELXL96 [21] software. Software
SHELXTL-PLUS [22] was used for graphics and prepara-
Table 1
Crystallographic data for 2 and 3
Compound
2
3
Empirical formula
Formula weight
Colour, habit
Crystal size (mm)
Crystal system
C86H88Cl2Fe2O2P4Rh2S2.3(CHCl3)
852.98
Dark red, block
0.46×0.54×0.32
Monoclinic
C50.50H52Cl1.25FeO1.50P2Rh1.25
1005.72
Dark red, prism
0.12×0.14×0.22
Orthorhombic
P21212
S
Space group
P21/c
Unit cell dimensions
,
a (A)
20.241(5)
25.948(4)
18.163(5)
90
99.50(3)
90
9409(4)
4
18.6380(3)
19.6650(3)
12.8810(2)
90
90
90
4721.1(1)
4
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
F(000)
4248
1.474
1.110
2066
1.415
0.961
Siemens SMART
Dcalc. (g cm−3
)
Absorption coefficient (mm−1
Diffractometer
)
Enraf–Nonius CAD-4
Temperature (K)
293(2)
150.0(2)
,
Radiation (u, A)
Scan mode
MoꢁKa (0.71073)
ꢀ
MoꢁKa (0.71073)
ꢀ
Scan step/speed (°)
Min/max scan speed (deg
–
0.3
–
1.2/8
min−1
)
Time per step (s)
–
30
Scan range in ꢀ
q range for data collection
Index ranges
Reflections collected
Independent reflections
Absorption correction
Max transmission
Min transmission
Solution method
1.1+0.35 tan q
2.04–25.07°
05h523, −305k50,−215l520
13957
13062 [Rint=0.0551]
Empirical („-curve)
0.735
–
1.51–28.00°
−215h525, −265k526, −185l514
36061
11384 [Rint=0.0785]
Empirical (SHELXTL-PLUS
0.596
)
0.614
Direct (SHELX-86)
0.463
Direct (SHELX-86)
Refinement method
Full-matrix least-squares on F2 SHELXL-93) Full-matrix least-squares on F2
( (SHELXL-93)
Treatment of hydrogen atoms Found from difference map with
Placed in calculated positions and refined using riding model
U=1.5Uiso(C)
Data/restraints/parameters
Goodness-of-fit on F2
13040/0/950
1.089
10543/4/543
1.170
Final R indices [I\2|(I)]
R indices (all data)
Absolute structure parameter
Extinction coefficient
R1=0.0670, wR2=0.1978
R1=0.1364, wR2=0.2387
R1=0.0648, wR2=0.1534
R1=0.1021, wR2=0.1874
−0.02(3)
0.00000(7)
0.0003(2)
Largest diff. peak and hole
1.453 and −0.714
2.021 and −0.855
(e A−3
)

112
R. Broussier et al. / Journal of Organometallic Chemistry 587 (1999) 104–112
[7] R. Broussier, S. Ninoreille, C. Legrand, B. Gautheron, J.
Organomet. Chem. 532 (1997) 55.
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4. Supplementary material
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC 116611 for compound 2 and
CCDC 116612 for compound 3. Copies of this informa-
tion may be obtained free of charge from: The Direc-
tor, CCDC, 12 Union Road, Cambridge, CB2 1EZ,
UK (Fax: +44-1223-336-033; email: deposit@ccdc.
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