Iron carbonyls with bulky thiolate ligands: Crystal structures of [Fe2(CO)6(μ-SC6H2 iPr3 -2,4,6)2] and (C6H2 iPr3 -2,4,6)2S2

Article abstract of DOI:10.1016/s0020-1693(98)00265-5

The reaction of Fe₃(CO)₁₂ and bulky thiols HSR (R = C₆H₂ⁱPr₃-2,4,6; C₆H₂Me₃-2,4,6) in toluene yielded compounds [Fe₂(CO)₆(μ-SR)₂] (R = C₆H₂ⁱPr₃-2,4,6 (1), C₆H₂Me₃-2,4,6 (2)). The substitution of one carbonyl by the phosphine Ph₂P(CH₂)₂Si(OEt)₃ in complex 1 afforded {Fe₂(CO)₅[Ph₂P(CH₂) ₂Si(OEt)₃](μ-SC₆H₂ ⁱPr₃-2,4,6)₂} (3). Mononuclear compounds [(η⁵-C₅H₅)Fe(CO)₂(SC ₆H₂ⁱPr₃-2,4,6)] (4) and {(η⁵-C₅H₅)Fe(CO)[Ph₂P(CH ₂)₂Si(OEt)₃](SC₆H₂ ⁱPr₃-2,4,6)} (5) have also been obtained. Compound 1 has been studied by X-ray diffraction and the structure determined reveals a distorted octahedron geometry around each iron atom and confirms the anti arrangement of R substituents, R = C₆H₂ⁱPr₃-2,4,6, in the molecule. The preparation of thiol HSC₆H₂ⁱPr₃-2,4,6 yielded the disulfide (C₆H₂ⁱPr₃-2,4,6)₂S ₂ as a by-product, whose structure has been solved by X-ray diffraction.

Full text of DOI:10.1016/s0020-1693(98)00265-5

Inorganica Chimica Acta 284 (1999) 14±19
Iron carbonyls with bulky thiolate ligands: crystal structures of
i
i
[Fe2(CO)6(m-SC6H2 Pr3-2,4,6)2] and (C6H2 Pr3-2,4,6)2S2
a,*
Esther Delgado , Elisa Hernandez , Noelia Mansilla ,
a
a
Â
Felix Zamora , L. Alfonso Martõnez-Cruz
a
b
Â
Â
Departamento de Quõmica Inorganica, Facultad de Ciencias, Universidad Autonoma, 28049 Madrid, Spain
a
Â
 Â
Instituto de Quõmica-Fõsica Rocasolano, Departamento de Cristalografõa, C.S.I.C., 28006 Madrid, Spain
Â
Â
b
Â
Received 19 February 1998; received in revised form 15 April 1998; accepted 13 May 1998
Abstract
i
The reaction of Fe3(CO)12 and bulky thiols HSR (R ˆ C6H2 Pr3-2,4,6; C6H2Me3-2,4,6) in toluene yielded compounds [Fe2(CO)6(m-SR)2]
i
(R ˆ C6H2 Pr3-2,4,6 (1), C6H2Me3-2,4,6 (2)). The substitution of one carbonyl by the phosphine Ph2P(CH2)2Si(OEt)3 in complex 1
5
i
i
afforded {Fe2(CO)5[Ph2P(CH2)2Si(OEt)3](m-SC6H2 Pr3-2,4,6)2} (3). Mononuclear compounds [(h -C5H5)Fe(CO)2(SC6H2 Pr3-2,4,6)] (4)
5
i
and {(h -C5H5)Fe(CO)[Ph2P(CH2)2Si(OEt)3](SC6H2 Pr3-2,4,6)} (5) have also been obtained. Compound 1 has been studied by X-ray
diffraction and the structure determined reveals a distorted octahedron geometry around each iron atom and con®rms the anti arrangement
i
i
i
of R substituents, R ˆ C6H2 Pr3-2,4,6, in the molecule. The preparation of thiol HSC6H2 Pr3-2,4,6 yielded the disul®de (C6H2 Pr3-2,4,6)2S2
as a by-product, whose structure has been solved by X-ray diffraction. # 1999 Elsevier Science S.A. All rights reserved.
Keywords: Iron complexes; Carbonyl complexes; Thiolate complexes; Crystal structures
1. Introduction
fact is very important from the point of view of the hydro-
desulfurisation reaction [9±11] as well as in organic synth-
eses [3].
Transition metal chemistry with organosulfur ligands has
played an important role in organic synthesis as well as in
biological systems [1±3]. Many petroleum based hydrocar-
bon feedstocks contain traces of sulfur compounds, thiols
among others [4±6]. From an environmental and economic
point of view, studies on the hydrodesulfurisation processes
are focussed on the ways to remove sulfur from the crude oil.
Compounds of formula [Fe2(CO)6(SR)2] as well as the
phosphine derivatives [Fe2(CO)(6 n)Ln(SR)2] (n ˆ 1, 2, or 3)
are well known [7,8]. Some of them exhibit an equilibrium
in solution between both syn±anti isomers but X-ray data
have con®rmed that the anti form is most stable in solid
state. However, as far as we know, no similar compounds
with sterically demanding SR ligands have been described.
This type of groups has recently received attention due to its
higher ability to form mononuclear compounds against the
behaviour showed by the sterically less demanding thiolate
ligands to bridge two metal centres. In addition, these
ligands seem to facilitate the cleavage of S±C bonds, this
On the other hand, complexes containing organofunctio-
nalised silanes have been described as adequate candidates
in supported catalysis [12,13]. In this context Allum et al.
[14] have studied the in¯uence of thiols on the hydrogena-
tion of ole®ns using Rh or Ir compounds with silane ligands
linked to silica.
Taking into account the well-known substitution reactions
of CO by phosphines as well as the hydrolysable properties
of R02P(CH2)2Si(OR)3 (R, R0 ˆ organic group) we wish to
report here the syntheses and characterisation of some iron
organometallic complexes with bulky aryl thiolate and
Ph2P(CH2)2Si(OEt)3 ligands. X-ray data on [Fe2(CO)6-
i
i
(m-SC6H2 Pr3-2,4,6)2] and (C6H2 Pr3-2,4,6)2S2 are also
included.
2. Experimental
All reactions were carried out under argon atmosphere
using Schlenk techniques [15]. Solvents were puri®ed
according to the standard methods [16]. The starting
*Corresponding author. Tel.: +34-1-397-5000; fax: +34-1-397-4833;
e-mail: esther.delgado@uam.es
0020-1693/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(98)00265-5

E. Delgado et al. / Inorganica Chimica Acta 284 (1999) 14±19
15
materials HSC6H2R3-2,4,6 (R ˆ iPr and Me) [17], Ph2-
P(CH2)2Si(OEt)3 [18], [CpFe(CO)2I] [19], were obtained as
previously described. IR spectra (2200±1600 cm 1) were
recorded on a Perkin-Elmer 1650 FT-IR spectrophotometer.
NMR (300 MHz, CDCl3): ꢁ (ppm) 7.80±7.26 (m, 10H,
C6H5), 6.87 (s, 1H, C6H2), 6.83 (s, 1H, C6H2), 4.44 (m,
2H, o-CH(CH3)2), 4.30 (m, 2H, o-CH(CH3)2), 3.65 (m, 6H,
OCH2), 2.78 (m, 2H, PCH2), 2.58 (m, 2H, p-CH(CH3)2),
1.26 (m, 9H, OCH2CH3), 1.17 (m, 24H, o-CH(CH3)2), 1.12
1
1H and 31Pf Hg NMR were recorded on a Bruker AMX-300
1
spectrometer. Elemental analyses were performed on a
Perkin-Elmer 240-B microanalyser. Positive ion FAB mass
spectra were carried out on a WG AutoSpec spectrometer,
using 3-nitrobenzyl alcohol as matrix.
(m, 12H, p-CH(CH3)2), 0.87 (m, 2H, CH2Si); 31Pf Hg
NMR (121 MHz, CDCl3): ꢁ (ppm) 64.7 (s, PPh2); IR
(cm 1) (n-hexane): ꢂ(CO) 2037 s, 1985 vs, 1967 s,
‡
‡
1925 m. Mass spectrum (FAB ): m/z ˆ 1098 (M ), 1042
‡
‡
‡
(M 2CO), 1014 (M 3CO), 986 (M 4CO), 958
i
‡
‡
‡
i
2.1. [Fe2(CO)6(ꢀ-SC6H2 Pr3-2,4,6)2] (1)
(M 5CO), 723 (M 5CO-SC6H2 Pr3), 694 (M CO-
‡
Ph2P(CH2)2Si(OEt)3), 667 (M 2CO-Ph2P(CH2)2Si-
‡
Compound 1 was obtained following a modi®ed synthesis
of a previous procedure [20]. A 100 ml Schlenk ¯ask
equipped with a stirrer bar, was loaded with 1.24 g
(2.46 mmol) of Fe3(CO)12 and degassed by evacuation/
argon-back®ll cycles. Then 30 cm3 of toluene, and 2.85 g
(OEt)3), 582 (M 5CO-Ph2P(CH2)2Si(OEt)3).
5
2.4. [(ꢃ -C5H5)Fe(CO)2(SC6H2 Pr3-2,4,6)] (4)
i
(12.1 mmol) of HSC6H2 Pr3 were added. The mixture was
To a solution of n-BuLi in n-hexane (0.8 cm3, 1.3 mmol)
at 308C was added slowly with stirring a n-hexane
i
stirred for 3 h at re¯ux. The solvent was removed in vacuo.
The resulting residue was chromatographed on silica gel
100. Elution with n-hexane afforded an orange band which
crystallised from the concentrated hexane solution at 208C
(1.68 g, 2.24 mmol, 91% yield). Anal. Calc. for Fe2C36-
H46O6S2: C, 57.61; H, 6.18. Found: C, 57.76; H, 6.04%.
1H NMR (300 MHz, CDCl3): ꢁ (ppm) 6.93 (s, 4H, C6H2),
4.31 (m, 4H, o-CH(CH3)2), 2.82 (m, 2H, p-CH(CH3)2), 1.28
(d, 24H, o-CH(CH3)2, J ˆ 7 Hz), 1.20 (d, 12H, p-CH(CH3)2,
J ˆ 7 Hz). IR (cm 1) (THF): ꢂ(CO) 2069 m, 2032 vs,
3
i
(10 cm ) solution of HSC6H2 Pr3 (0.29 g, 1.23 mmol).
The mixture was allowed to reach 08C and then a THF
(15 cm3) solution of [CpFe(CO)2I] (0.25 g, 0.8 mmol) was
added. The resulting solution was stirred at room tempera-
ture for 2 h. The solvent was removed in vacuo and the
residue chromatographed on silica gel 100. Elution with n-
hexane/THF (20:1) gave a green band. The solvent was
removed and the residue recrystallised from THF/n-hexane
(1:5) affording the product in 51% yield. Anal. Calc. for
FeC22H28O2S: C, 64.08; H, 6.84. Found: C, 63.27; H,
7.12%. 1H NMR (300 MHz, CDCl3): ꢁ (ppm) 6.84 (s,
‡
‡
2000 s, 1990 s. Mass spectrum (FAB ): m/z ˆ 750 (M ),
‡
‡
‡
694 (M 2CO), 666 (M 3CO), 638 (M 4CO), 610
i
‡
‡
‡
(M 5CO), 582 (M 6CO), 375 (M 5CO-SC6H2 Pr3),
‡
2H, C6H2), 4.93 (s, 5H, C5H5), 4.04 (s, 2H, o-CH(CH3)2),
1
i
347 (M 6CO-SC6H2 Pr3).
2.79 (s, 1H, p-CH(CH3)2), 1.22 (m, 18H, CH3). IR (cm
(THF): ꢂ(CO) 2022 s, 1976 s. Mass spectrum (FAB ):
)
‡
‡
‡
‡
i
2.2. [Fe2(CO)6(ꢀ-SC6H2Me3-2,4,6)2] (2)
m/z ˆ 412 (M ), 356 (M 2CO), 149 (M SC6H2 Pr3-
CO).
Using the same procedure as above with HSC6H2Me3-
2,4,6 (85% yield). Anal. Calc. for Fe2C24H22O6S2: C, 49.51;
H, 3.81. Found: C, 49.03; H, 3.88%.1H NMR (300 MHz,
CDCl3): ꢁ (ppm) 6.87 (s, 4H, C6H2), 2.60 (s, 12H, o-CH3),
2.23 (s, 6H, p-CH3). IR (cm 1) (THF): ꢂ(CO) 2071 m, 2035
5
i
2.5. {(ꢃ -C5H5)Fe(CO)[Ph2P(CH2)2Si(OEt)3](SC6H2 Pr3-
2,4,6)} (5)
‡
‡
5
i
vs, 1996 s. Mass spectrum (FAB ): m/z ˆ 582 (M ), 567
To a green solution of [(h -C5H5)Fe(CO)2(SC6H2 Pr3-
2,4,6)] (0.16 g, 0.38 mmol) in CH2Cl2 (20 cm3),
Ph2P(CH2)2Si(OEt)3 (0.15 g, 0.40 mmol) was added. After
stirring for 2 h at re¯ux, the solvent of the brown-reddish
solution was removed in vacuo and the residue recrystallised
from CH2Cl2/n-hexane at 208C (24% yield). Anal. Calc.
for FeC41H57O4SPSi: C, 64.72; H, 7.55. Found: C, 64.60; H,
7.70%. 1H NMR (300 MHz, CDCl3): ꢁ (ppm) 7.49±7.37 (m,
10H, C6H5), 6.84 (s, 2H, C6H2), 4.2 (s, 5H, C5H5), 3.97 (m,
3H, CH(CH3)2), 3.75 (m, 6H, OCH2), 2.63 (t, 2H, PCH2, J ˆ
7 Hz), 1.25 (m, 9H, OCH2CH3), 1.20 (m, 18H, CH(CH3)2),
‡
‡
‡
‡
(M CH3), 554 (M CO), 526 (M 2CO), 470
(M 4CO), 442 (M 5CO), 431 (M SC6H2Me3), 414
‡
‡
‡
(M 6CO).
i
2.3. {Fe2(CO)5[Ph2P(CH2)2Si(OEt)3](ꢀ-SC6H2 Pr3-
2,4,6)2} (3)
i
To a solution of [Fe2(CO)6(m-SC6H2 Pr3-2,4,6)2] (0.17 g,
0.23 mmol) in THF (25 cm3), Ph2P(CH2)2Si(OEt)3 (0.26 g,
0.69 mmol) was added. The solution was stirred for 7 days
at room temperature. The solvent was removed in vacuo and
the resulting residue was chromatographed on silanised
silica gel 60. Elution with toluene gave a red band of
compound 3 (30% yield). Anal. Calc. for Fe2C55H75O8-
1
0.91 (m, 2H, CH2Si); 31Pf Hg NMR (121 MHz, CDCl3): ꢁ
1
(ppm) 67.4 (s, PPh2); IR/cm (CH2Cl2): ꢂ(CO) 1937 s.
‡
‡
‡
Mass spectrum (FAB ): m/z ˆ 760 (M ), 732 (M CO),
‡
‡
i
667 (M CO±Cp), 497 (M CO-SC6H2 Pr3), 356
(M CO±Ph2P(CH2)2Si(OEt)3).
‡
1
S2PSi: C, 60.11; H, 6.88. Found: C, 59.42; H, 6.57%. H

16
E. Delgado et al. / Inorganica Chimica Acta 284 (1999) 14±19
Table 1
2.8. Crystal data for complex 6
Crystallographic data
The X-ray measurements for 6 were carried out on a
CAD4 Enraf-Nonius diffractometer at room temperature,
1
6
Empirical formula
Fw
C36H46Fe2O6S2
750.55
C30H46S2
470.79
Ê
using graphite monochromated Cu Ka radiation (1.5407 A).
Selected crystallographic data are listed in Table 1. ꢄ Range
for data collection: 4±608, index ranges: 0 ꢀ h ꢀ 19, 0 ꢀ k
ꢀ17, 0 ꢀ 1 ꢀ24. Scattering factors, dispersion corrections
and absorption coef®cients were taken from the Interna-
tional Tables for Crystallography [21]. The structure was
solved by direct methods using SIR92 [22], and was re®ned
by least squares analysis using SHELX93 [23,24] with
anisotropic thermal parameters for non-H atoms. The posi-
tions of the hydrogen atoms were re®ned with distance
restraints for the C±H distances. The extinction correction
was carried out using SHELX93 [23,24], the extinction
factor being 0.0012 (2). Final R indices R1 ˆ 0.0765,
wR2 ˆ 0.2056 (for observed data), R indices R1: 0.981,
wR2 ˆ 0.2428 (for all data), largest differential peak and
Crystal colour and habit elongated prism
elongated prism
0.17 Â 0.19 Â 0.24
orthorhombic
Crystal dimension (mm) 0.17 Â 0.19 Â 0.50
Crystal system
Lattice parameters:
monoclinic
Ê
a (A)
Ê
b (A)
Ê
c (A)
10.771(1)
27.81(1)
13.639(2)
90
17.589(1)
15.671(3)
22.119(2)
90
ꢅ (8)
ꢆ (8)
110.33(1)
3831(1)
P21/a
90
Ê 3
V (A )
Space group
6096.8(1)
Pbca
3
)
Dcalc. (Mg m
1.301
1.026
Z
4
8
Ê
Ê
Radiation
1
Mo Ka (ꢇˆ0.7107 A)
Cu Ka (1.5407 A)
1.662
ꢀ (mm
2ꢄmax (8)
Reflections collected
)
0.906
25
60
6648
4538
3
Ê
hole 0.557 and 0.393 e A
.
Independent reflections 5300 (I > 2ꢈ(I))
3027 (I > 2ꢈ(I))
290
No. of parameters
Residuals R; Rw
Goodness of fit
415
0.106; 0.270
1.191
0.659
0.981, 0.2428
1.048
0.557
3. Results and discussion
Largest differential
3
Ê
peak (e A
)
Examples of [Fe2(CO)6(m-SR)2] and [Fe2(CO)5(PPh3)(m-
SR)2] derivatives are well known, however, the number of
them with bulky organic group are scarce [26,27]. On the
other hand, highly demanding aromatic thiolate ligands
seem to show a different behaviour such as a lower tendency
to bridge two metal centres when compared with the less
hindered ones.
i
2.6. (C6H2 Pr3-2,4,6)2S2 (6)
Compound 6 was obtained in the preparation of
i
HSC6H2 Pr3-2,4,6 ligand [17]. 1H NMR (300 MHz,
CDCl3): ꢁ (ppm) 6.92 (s, 4H, C6H2); 3.52 (m, 4H,
o-CH(CH3)2); 2.82 (m, 2H, p-CH(CH3)2); 1.20 (d, 12H,
p-CH(CH3)2); 1.00 (d, 24H, o-CH(CH3)2).
Taking into account these facts initially we carried out the
i
reactions between Fe3(CO)12 and HSR (R ˆ C6H2 Pr3-2,4,6
or C6H2Me3-2,4,6) in order to compare the results with
those previously observed for alkyl or not-demanding aryl
thiols.
2.7. Crystal data for complex 1
The new complexes were characterised by elemental
1
The X-ray measurements for 1 were carried out on a PW
1100 diffractometer at room temperature, using graphite
analysis as well as by IR, H; 31 P NMR and FAB mass
spectroscopy (see Section 2). The analytical data of com-
Ê
monochromated Mo Ka radiation (0.7107 A). Relevant
pounds 1 and 2 are in agreement with the formula
i
crystallographic data are listed in Table 1. ꢄ Range for data
collection: 2±258, index ranges: 0 ꢀ h ꢀ 12, 0 ꢀ k ꢀ33, 15
ꢀ l ꢀ 15. Scattering factors, dispersion corrections and
absorption coef®cients were taken from the International
Tables for Crystallography [21]. The structure was solved
by direct methods using SIR92 [22], and was re®ned by least
squares analysis using SHELX93 [23,24], with anisotropic
thermal parameters for non-H atoms. The positions of the
hydrogen atoms were re®ned with distance restraints for the
C±H distances. No extinction correction was applied.
Absorption was corrected using É-scan data [25], 1.104
and 0.727, being the maximum and minimum absorption
corrections. Final R indices R1 ˆ 0.083, wR2 ˆ 0.249 (for
observed data), R indices R1: 0.106, wR2 ˆ 0.270 (for all
data), largest differential peak and hole 0.659 and 0.670
[Fe2(CO)6(m-SR)2] (R ˆ C6H2 Pr3-2,4,6, C6H2Me3-2,4,6).
The ꢂ(CO) IR pattern in THF solution of both complexes is
similar to those found for other related derivatives [28,29].
1
The H NMR spectra at room temperature reveal the pre-
sence of organic groups present in the aromatic rings of both
compounds. The proposed structures of 1 and 2 on the basis
of analytical and spectroscopic data were con®rmed by X-
ray diffraction on 1 (Fig. 1).
The species Ph2P(CH2)2Si(OEt)3 like a phosphine may
coordinate to metallic centres through the phosphorous
atom. On the other hand, the presence of a hydrolysable
group such as OEt in it, should facilitate the attachment of
the complex to a support like silica. The importance from an
industrial point of view, of supported organometallic com-
pounds prompted us to carry out the reaction between
3
.
i
Ê
e A
[Fe2(CO)6(m-SC6H2 Pr3-2,4,6)2] and Ph2P(CH2)2Si(OEt)3

E. Delgado et al. / Inorganica Chimica Acta 284 (1999) 14±19
17
Fig. 1. ORTEP (50% ellipsoids) plot of compound 1.
in order to prepare {Fe2(CO)5[Ph2P(CH2)2Si(OEt)3](m-
SC6H2 Pr3-2,4,6)2} as reagent for the syntheses of supported
sponding to loss of carbonyls, thiol or phosphine ligands
were showed in the FAB mass spectrum of both complexes.
i
i
catalyst. Such as has been observed in analogous com-
pounds [Fe2(CO)5(PPh3)(m-SEt)2] [30,31] and [Fe2(CO)4-
(PPh3)2(m-SPh)2] [32,33], etc., the four bands displayed in
the carbonyl region of the IR spectrum of 3 are indicative of
the substitution of one carbonyl by one phosphine ligand
from complex 2. In 31P NMR a resonance at 66.4 ppm has
been reported for [Fe2(CO)5(PPh3)(m-SEt)2] appearing at
44.7 ppm for [Fe2(CO)4(PPh3)2(m-SEt)2] [31]. Because of
the free triphenylphosphine shows a resonance in 31P NMR
quite close to that observed for the free Ph2P(CH2)2-
Si(OEt)3, we believe that the signal at 64.7 ppm exhibited
for 3 is in agreement with the monosubstitution. Although
the reaction was carried out using an excess of phosphine,
no disubstituted derivative was observed, may be due to the
presence of bulky ligands in the molecule. The resonances
corresponding to the organic groups of thiolate and phos-
phine ligands are displayed in the 1H NMR spectrum. In the
positive FAB mass spectra of 1±3 the molecular ion signal,
although weak, as well as gradual loss of CO, SR or
phosphine group are observed.
Finally, formation of the disul®de (C6H2 Pr3-2,4,6)2S2, as
a by-product, is observed following the method previously
described by Blower et al. [17] for the synthesis of
i
HSC6H2 Pr3-2,4,6. Crystallisation in CH2Cl2 at 208C gave
diffraction-quality crystals of (C6H2 Pr3-2,4,6)2S2 (6) which
i
could be easily separated from the mixture. This compound
1
was characterised by H NMR and its structure con®rmed
by X-ray diffraction.
Table 2
Ê
Selected bond distances (A) and angles (8) for compounds 1 and 6
1
6
Fe(1)±Fe(2)
Fe(1)±S(1)
Fe(1)±S(2)
2.466(2)
2.321(2)
2.311(2)
S(1)±S(2)
S(1)±C(1)
S(2)±C(16)
2.060(3)
1.787(3)
1.783(3)
Fe(2)±S(1)
Fe(2)±S(2)
2.319(2)
2.318(2)
C(1)±S(1)±S(2)
S(1)±S(2)±C(16)
104.5(1)
102.8(1)
S(2)±Fe(1)±S(1)
S(2)±Fe(2)±S(1)
Fe(2)±S(1)±Fe(1)
Fe(1)±S(2)±Fe(2)
74.46(7)
74.37(7)
64.22(6)
64.40(6)
Reaction between [(h5-C5H5)Fe(CO)2I] and LiSC6-
i
H2 Pr3-2,4,6 in THF afforded compound 4. The substitution
of one carbonyl by Ph2P(CH2)2Si(OEt)3 in compound 4 was
carried out in re¯uxing THF giving compound 5. Satisfac-
tory elemental analyses according to the formula [(h5-
5
i
C5H5)Fe(CO)2(SC6H2 Pr3-2,4,6)] (4) and {(h -C5H5)Fe-
i
(CO)[Ph2P(CH2)2Si(OEt)3](SC6H2 Pr3-2,4,6)} (5) were
obtained. In the IR spectra, the bands exhibited at 2022
1
1
and 1976 cm for 4 and 1973 cm for 5 were in agree-
ment with those found in similar compounds [34±37].
The 1H NMR spectra of both compounds consist of
several signals corresponding to the cyclopentadienyl and
thiolate ligands; in addition compound 5 exhibits the reso-
nance characteristics of the phosphine. In this case a signal
at 67.4 ppm was observed in the 31P NMR spectrum. The
molecular ion signal, in addition to the fragments corre-
Fig. 2. ORTEP (50% ellipsoids) plot of compound 6.

18
E. Delgado et al. / Inorganica Chimica Acta 284 (1999) 14±19
Fig. 3. PLUTO diagram showing the molecular packing of 6 projected on the ab plane. Holes along c are occupied by faced S-bridges belonging to the
neighbour molecules.
i
3.1. Crystal structure of [Fe2(CO)6(ꢀ-SC6H2 Pr3-2,4,6)2]
(1)
bridges are situated. The mentioned holes are parallel to the
c-axis, and each molecule is located with its S±S pair facing
to another S-bridge of a neighbour molecule as shown in
Ê
Fig. 3 [43]. The S±S bond distance of 2.060 (3) A agrees
well with the values observed in related compounds:
The ORTEP representation of compound 1 is shown in
Fig. 1 [38]. Selected bond lengths and angles are given in
Table 2. The compound shows a Fe±Fe bond almost sym-
metrically double bridged by two thiolate ligands with the
organic group anti to each other. The Fe±Fe bond distance of
Ê
(C6H5)2S2 (2.030 A) [44,45], (C6F5)2S2 (2.059 A), [42]
Ê
Ê
and [C6H2(CF3)3]2S2 (2.053 A) [46].
The torsion angle of 77.58 formed by the two sulfur atoms
and their respective closest neighbours C1 and C16, is similar
to the values found for the above mentioned compounds.
Ê
2.466(2) A is shorter than that reported for similar deriva-
Ê
tives, for instance [Fe2(CO)6(m-SEt)2] (2.537(10) A) [39],
Ê
[Fe2(CO)5(PPh3)(m-SEt)2] (2.524(9) A) [30,31] and
Ê
[Fe2(CO)6(m-SPh)2] (2.516 A) [40]. In 1 each iron atom
4. Supplementary material
is surrounded by three carbonyls and two sulfurs at the
corner of a distorted octahedron. The individual Fe±C±O
angles do not deviate signi®cantly from linearity and Fe±S
distances ®t well with the value observed in related com-
plexes [30,31,41,42].
A complete description of the crystallographic methods
and details of the structure determination and re®nement are
available from the authors on request.
Acknowledgements
i
3.2. Crystal structure of (C6H2 Pr3-2,4,6)2S2 (6)
Financial support was generously provided by the Direc-
Selected bond distances and angles are listed in Table 2
and a drawing of the molecule structure showing the atom-
numbering scheme is given in Fig. 2 [38]. Crystals are built
up of discrete molecules showing a sulfur±sulfur bridge
between the 2,4,6-isopropyl trisubstituted aromatic rings.
There is one crystallographically independent molecule
stacked in such a way by forming holes, in which S±S
Â
cion General de Investigacion Cientõ®ca y Tecnica, Spain
(Project PB93-0250).
Â
Â
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References
[1] W. Lovenberg, Iron±Sulfur Proteins, Academic Press, New York,
vols. 1±3, 1973, 1974, 1976.

E. Delgado et al. / Inorganica Chimica Acta 284 (1999) 14±19
19
[2] W. Kaim, B. Schwederski, Bioinorganic Chemistry: Inorganic
Elements in the Chemistry of Life, Wiley, Chichester, UK, 1994
and references therein.
[24] G.M. Sheldrick, (1993), in preparation for J. Appl. Crystallogr.,
computing-structure-solution SHELXS-86 (Sheldrick, 1990)- com-
puting-structure-refinement SHELXS-93 (Sheldrick, 1993).
[25] A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr., Sect. A
24 (1968) 351.
[3] L.L. Yeung, Y.Ch. Yip, T.-Y. Luh, J. Org. Chem. 55 (1990) 1874.
[4] D.A. Vicic, W.D. Jones, Organometallics 16 (1997) 1912.
[5] R.J. Angelici, Acc. Chem. Res. 21 (1988) 387.
[26] E. Kostiner, M.L.N. Reddy, D.S. Urch, A.G. Massey, J. Organomet.
Chem. 15 (1968) 383.
[6] B.C. Weigand, C.M. Friend, Chem. Rev. 92 (1992) 491.
[7] R.B. King, M.B. Bisnette, Inorg. Chem. 4 (1965) 482.
[8] J.A. de Beer, R.J. Haines, R. Greatrex, N. Greenwood, J. Chem. Soc.
A (1971) 3271.
[27] A. Winter, L. Zsolnai, G. Huttner, Chem. Ber. 115 (1982) 1286.
[28] G. Bor, J. Organomet. Chem. 94 (1975) 181.
[29] D. Seyferth, R.S. Henderson, L.-Ch. Song, Organometallics 1 (1982)
125.
[9] T.E. Burrow, A. Hills, D.L. Hughes, J.D. Lane, R.H. Morris, R.L.
Richards, J. Chem. Soc., Dalton Trans. (1991) 1813.
[10] T.E. Burrow, D.L. Hughes, A.J. Lough, M.J. Maguire, R.H. Morris,
R.L. Richards, J. Chem. Soc., Dalton Trans. (1995) 2583.
[30] P.C. Ellgen, J.N. Gerlach, Inorg. Chem. 12 (1973) 2526.
Â
[31] E. Delgado, E. Hernandez, O. Rossell, M. Seco, E. Gutierrez-Puebla,
C. Ruiz, J. Organomet. Chem. 455 (1993) 177.
[32] L. Maresca, F. Greggio, G.S. Brignadello, G. Bor, Inorg. Chim. Acta
5 (1971) 667.
Â
[11] C. Bianchini, P. Frediani, V. Herrera, M.V. Jimenez, A. Meli, L.
 Â
Rincon, R.A. Sanchez-Delgado, F. Vizza, J. Am. Chem. Soc. 117
(1995) 4333.
[33] J.A. De Beer, R.J. Haines, J. Organomet. Chem. 36 (1972) 297.
[34] M. Ahmad, R. Bruce, G.R. Knox, J. Organomet. Chem. 6 (1966) 1.
[35] P.M. Treichel, E.K. Rublein, J. Organomet. Chem. 423 (1992) 391.
[36] J. Cooke, M. Green, F.G.A. Stone, J. Chem. Soc. (A) (1968) 170.
[37] P.M. Treichel, L.D. Rosenhein, M.S. Schmidt, Inorg. Chem. 22
(1983) 3960.
[12] U. Kiiski, T.A. Pakkanen, O. Krause, J. Mol. Catal. 50 (1989) 143.
[13] B.C. Gates, H.H. Lamb, J. Mol. Catal. 52 (1989) 1.
[14] K.G. Allum, R.D. Hancock, I.V. Howell, T.E. Lester, S. Mckenzie,
R.C. Pitkethly, P.J. Robinson, J. Organomet. Chem. 107 (1976)
393.
[15] D.F. Shriver, M.A. Drezdzon, The Manipulation of Air Sensitive
Compounds, 2nd ed, Wiley, New York, 1986.
[38] C.K. Johnson, ORTEP, Report ORNL-3794, Oak Ridge National
Laboratory, Oak Ridge, TN, 1965.
[16] D.D. Perrin, W.L.F. Armarego, D.R. Perrin, Purification of
Laboratory Chemicals, 2nd ed, Pergamon, Oxford, 1980.
[17] P.J. Blower, J.R. Dilworth, J.P. Hutchinson, J.A. Zubieta, J. Chem.
Soc., Dalton Trans. (1985) 1533.
[39] L.F. Dahl, C.-H. Wei, Inorg. Chem. 2 (1963) 328.
[40] W. Henslee, R.E. Davis, Cryst. Struct. Comm. 1 (1972) 403.
[41] G. Le Borgne, D. Grandjean, R. Mathieu, R. Poilblanc, J.
Organomet. Chem. 131 (1977) 429.
[18] J. Kowalski, J. Chojnowski, J. Organomet. Chem. 365 (1988)
285.
[42] C.M. Woodard, D.S. Brown, J.D. Lee, A.G. Massey, J. Organomet.
Chem. 121 (1976) 333.
[19] R.B. King, F.G.A. Stone, Inorg. Synth. 7 (1963) 110.
[20] J.A. De Beer, R.J. Haines, J. Organomet. Chem. 24 (1970) 757.
[21] International Tables for Crystallography, Kluwer, Dordrecht, The
Netherlands, vol. C, 1992.
[43] S.R. Hall, J.M. Stewart (Eds.), XTAL3.2, (1994), Universities of
Western Australia and Maryland, Perth, WA, Australia.
[44] J.D. Lee, M.W.R. Bryant, Acta Crystallogr., Sect. B 25 (1969) 2094.
[45] R.E. Marsch, Acta Crystallogr. 5 (1952) 458.
[22] A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, C. Giacovazzo,
A. Guagliardi, G. Polidori, J. Appl. Crystallogr. 27 (1994) 435.
[23] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[46] A. Edelmann, S. Brooker, N. Bertel, M. Noltemeyer, H.W. Roesky,
G.M. Sheldrick, F.T. Edelmann, Z. Naturforsch., Teil B 47 (1992)
305.