Alkynethiolate ligands in the syntheses of iron carbonyl derivatives. Crystal structure of [(η5-C5H5 Fe(CO)2(SC≡CSiMe3)]

Article abstract of DOI:10.1016/S0022-328X(01)01444-9

The complexes [η⁵-C₅H₅)Fe(CO)₂(SC≡CR)] (R = Bu, SiMe₃) have been obtained by reaction of [(η⁵-C₅H₅)Fe(CO)₂I] and the corresponding LiSC≡CR. These are the first examples of mononuclear iron compounds containing alkynethiolate ligands. The crystal structure of [(η⁵-C₅H₅)Fe(CO)₂(SC≡CSiMe₃)] has been determined by X-ray diffraction. The role of [(η⁵-C₅H₅)Fe(CO)₂(SC≡CSiMe₃)] as a metalloligand in its reactions with metal carbonyls has been explored.

Full text of DOI:10.1016/S0022-328X(01)01444-9

Journal of Organometallic Chemistry 649 (2002) 21–24
www.elsevier.com/locate/jorganchem
Alkynethiolate ligands in the syntheses of iron carbonyl
derivatives. Crystal structure of [(h5-C5H5)Fe(CO)2(SCꢀCSiMe3)]
Esther Delgado a,*, Bruno Donnadieu b, Silvia Garc´ıa a, Fe´lix Zamora a
a Departamento de Qu´ımica Inorga´nica, Facultad de Ciencias, Uni6ersidad Auto´noma de Madrid, 28049 Madrid, Spain
b Ser6ice de Cristallochimie, Laboratoire de Chimie de Coordination CNRS, 31077 Toulouse, France
Received 26 July 2001; accepted 16 November 2001
Abstract
The complexes [(h5-C5H5)Fe(CO)2(SCꢀCR)] (R=tBu, SiMe3) have been obtained by reaction of [(h5-C5H5)Fe(CO)2I] and the
corresponding LiSCꢀCR. These are the first examples of mononuclear iron compounds containing alkynethiolate ligands. The
crystal structure of [(h5-C5H5)Fe(CO)2(SCꢀCSiMe3)] has been determined by X-ray diffraction. The role of [(h5-
C5H5)Fe(CO)2(SCꢀCSiMe3)] as a metalloligand in its reactions with metal carbonyls has been explored. © 2002 Elsevier Science
B.V. All rights reserved.
Keywords: Cyclopentadienyl iron complexes; Alkynethiolates derivatives; X-ray diffraction
2. Results and discussion
1. Introduction
[(h5-C5H5)Fe(CO)2(SCꢀCR)] [R=tBu (1), SiMe3 (2)]
The use of organosulfur ligands in transition metal
chemistry has been of interest due to the importance of
compounds have been prepared by reacting [(h5-
C5H5)Fe(CO)2I] and LiSCꢀCR. In the course of these
the formation or cleavage of CꢁS bonds either from
reactions we have observed that a strict control of the
biological, industrial or environmental point of view [1].
temperature and reaction time is necessary in order to
Although thiolate or acetylide chemistry has been
minimize the formation of Fp2 as by-product. Although
widely explored, just a few complexes containing
the above reactions are almost quantitative (based on
alkynethiolate ligands are known [2]. To our knowl-
edge, the only iron compounds with this type of ligands
spectroscopic data) only compound 2 is stable enough
in solution to be isolated with a good yield as a
crystalline compound.
The spectroscopic data of compounds 1 and 2 are in
agreement with their formulation. Thus, the IR spectra
show in both cases two strong CꢁO and a weak CꢁC
that have been reported are [Fe2(m-CꢀCPh)(m-
SCꢀCPh)(CO)6], prepared by reaction of Fe3(CO)12 and
S(CꢀCPh)2 [3], and [Fe2(m-SMe)(m-SCꢀCPh)(CO)6] ob-
tained from [Fe2(m-S2)(CO)6] by cleavage of the SꢁS
bond using LiCꢀCPh and further addition of MeI [4].
stretching bands at the expected wavenumbers. The
Keeping the above mentioned in mind, we have
presence of acetylide ligand is clearly denoted by the
considered of interest to synthesize new mononuclear
complexes such as [(h5-C5H5)Fe(CO)2(SCꢀCR)] and to
study their role as building blocks for the preparation
of di- and polynuclear compounds.
observation of a-C and b-C resonances, respectively,
(77.7 and 84.2 ppm for 1; 80.1 and 108.8 ppm for 2), in
t
addition to the characteristic Bu or SiMe3 resonances.
Although the chemical shift difference between a-C and
b-C in 2 is large, it is still within the range observed for
other complexes containing the trimetylsilylacetylide
ligand [2b].
* Corresponding author. Tel.: +34-91-3975268; fax: +34-91-
3974833.
E-mail address: esther.delgado@uam.es (E. Delgado).
The structure of [(h5-C5H5)Fe(CO)2(SCꢀCSiMe3)]
compound (2) (Fig. 1) was confirmed by X-ray diffrac-
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01444-9

22
E. Delgado et al. / Journal of Organometallic Chemistry 649 (2002) 21–24
on the contrary, reports concerning the related
alkynethiolate complexes are scarce. In this context, we
have explored its potential as building block of [(h5-
C5H5)Fe(CO)2(SCꢀCSiMe3)] by reaction with some
metal carbonyls.
tion. Although the synthesis of a few mononuclear
ruthenium complexes containing alkynethiolate ligands
has been previously reported [2], compound 2 repre-
sents the first example of a Group 8 metal complex that
has been characterized by X-ray diffraction. Compound
2 exhibits a typical three-legged piano-stool structure.
A plane of symmetry passing through the alkynethio-
late group (S, C(2), C(3), and Si atoms), the C(12) and
the Fe atoms are observed in the molecule. The exis-
tence of the CꢀC group is confirmed by the bond
Unfortunately all reactions carried out between com-
pound 2 and Fe(CO)5, Fe2(CO)9 or Fe3(CO)12 at differ-
ent temperatures and using either THF or toluene as
solvents, in order to obtain higher nuclearity com-
pounds failed probably due to the instability of the
compound [(h5-C5H5)Fe2(CO)6(m-SCꢀCSiMe3)], which
was probably formed at the first stage. Fp2 and
[Fe2(CO)6(m-SCꢀCSiMe3)2] compounds [IR (cm−1, hex-
ane): 2078 (m), 2038 (s), 2007 (s), 2002 (s), 1991 (w),
1979 (w). 1H-NMR (CDCl3): l (ppm) 5.00 (s, 5H,
C5H5), 0.12 (s, 9H, SiMe3)] were the only products
obtained in these reactions. This decomposition process
is reminiscent of others observed in related mononu-
clear iron thiolate derivatives [9].
,
distance C(2)ꢁC(3) [1.205(4) A] (Table 1) which is
analogous to those found for [(h5-C5H5)Fe(CO)2-
,
(CꢀCR)] [R=SiMe3, 1.201(5) A [5] and R=Ph,
,
,
1.201(9) A [6]]. The FeꢁS distance [2.3092(9) A] and the
FeꢁSꢁC(2) angle [105.17(8)°] are similar to those mea-
sured for [(h -C5H5)Fe(CO)2(SEt)] [2.296(2) A and
5
,
107.0(2)°] [7]. Two CH3 groups from the trimethylsilyl
present a disorder around the mirror (m) parallel to the
bc plane, which is a plane of symmetry for the
molecule. The atoms C(51) and C(52) are statistically
distributed on the each sides of this mirror with the
ratio of occupancy equal to 60/40%.
The use of transition metal thiolate or acetylide
derivatives as precursors in the syntheses of di- or
polynuclear compounds has been widely developed [8],
We have also studied the reaction between [(h5-
C5H5)Fe(CO)2(SCꢀCRSiMe3)] (2) and the stoichiomet-
ric amount of Co2(CO)8 to produce [(h5-C5H5)Fe-
(CO)2(m3, h3-SCꢀCSiMe3)Co2(CO)6] (3) compound. The
overall composition of this complex is confirmed
through a FAB+ mass spectrum, which exhibits peaks
corresponding to the (M++1) ion, as well as fragments
derived from loss of up to eight carbonyl ligands. On
the other hand, the absence of the w(CꢀC) in the IR
spectrum as well as the significant shift to lower field of
the signals corresponding to acetylide groups (93.9 and
128.2 ppm) with the presence of two resonances at
200.7 and 212.4 ppm assigned to the carbonyl groups in
the 13C-NMR spectrum, are indicative of the coordina-
tion of the cobalt carbonyl fragment to the CꢀCR
group. Attempts to obtain a FeCo2 cluster by forcing
CO elimination from 3 have been unsuccessful.
3. Experimental
3.1. Synthesis of [(p5-C5H5)Fe(CO)2(SCꢀCR)] (R=tBu
(1), SiMe3 (2))
Fig. 1. View of [(h5-C5H5)Fe(CO)2(SCꢀCSiMe3)] (2).
Details of the synthesis of 1 also apply to 2. A
solution of LiSCꢀCtBu (1.1 mmol) in THF (10 ml) at
−45 °C was slowly added with stirring to a solution of
[(h5-C5H5)Fe(CO)2I] (0.300 g, 0.99 mmol) in THF (15
ml) at the same temperature. The resulting mixture was
allowed to reach 0 °C and then stirred for 30 min. The
solvent was removed under vacuum and the residue
extracted with n-hexane (3×10 ml) at 0 °C. Then the
solution was concentrated to a volume of ca. 10 ml and
cooled at −76 °C. The crystals thus obtained were
filtered off, washed with cold n-hexane and dried under
vacuum, 0.04 g, 13.9% yield. For R=SiMe3 (2), 0.187
g, 61.6% yield.
Table 1
Selected bond distances (A) and angles (°) of [(h5-
,
C5H5)Fe(CO)2(SCꢀCSiMe3)] (2)
Bond lengths
FeꢁC(1)
FeꢁS
1.7753(17)
2.3092(9)
1.678(3)
C(2)ꢁC(3)
SiꢁC(3)
SiꢁC(4)
1.205(4)
1.827(3)
1.844(3)
SꢁC(2)
Bond angles
C(1)ꢁFeꢁC(1A)
C(1A)ꢁFeꢁS
C(2)ꢁSꢁFe
94.38(12)
91.28(7)
105.17(9)
109.06(15)
C(4)ꢁSiꢁC(51)
C(2)ꢁC(3)ꢁSi
C(3)ꢁC(2)ꢁS
105.9(3)
177.5(2)
179.4(2)
C(3)ꢁSiꢁC(4)

E. Delgado et al. / Journal of Organometallic Chemistry 649 (2002) 21–24
23
Compound 1: IR (cm−1, THF): 2141 (w; CꢀC), 2032
(s), 1987 (s). IR (cm−1, KBr): 2137 (w; CꢀC), 2045 (s),
mated Mo–Ka radiation (u=0.71073 A), overall com-
pleteness to 2q: 95.9%. Data were corrected for
absorption using numerical methods [10], theses correc-
tions were optimized with the aid of the software [11],
using a maximum and a minimum transmission of
0.837 and 0.492, respectively. Structure has been solved
by Direct Methods using SIR92 [12] and refined by
least-squares procedures on a F2 with the aid of
,
1
1994 (s). H-NMR (CDCl3): at 20 °C, l (ppm) 4.97 (s,
5H, C5H5), 1.18 (s, 9H, C(CH3)3). 13C{1H}-NMR
(CDCl3): at 20 °C, l (ppm) 28.7 [C(CH3)3], 31.4
[C(CH3)3], 77.7 (SCꢀC), 84.2 (SCꢀC), 85.7 (C5H5),
212.3 (CO). Anal. Calc. for C13H14O2SFe (Found): C,
53.81 (52.75); H, 4.86 (4.76)%.
Compound 2: IR (cm−1, THF): 2059 (m; CꢀC), 2034
(SHELXL97) [13].
(s), 1991 (s). IR (cm−1, KBr): 2062 (vw; CꢀC), 2038
The model reached Final R indices: R1=0.0197,
1
(m), 1996 (s), 1978 (sh). H-NMR (CDCl3): at 20 °C, l
wR2=0.0502 for 1423 reflections with I\2|(I), and
R1=0.0201, wR2=0.0503 on all data, Goodness-of-fit
(S)=1.069.
(ppm) 0.12 [s, 9H, Si(CH3)3], 5.00 (s, 5H, C5H5).
13C{1H}-NMR (CDCl3):
l (ppm) at 20 °C, 0.5
(Si(CH3)3), 80.1 (SCꢀC), 85.8 (C5H5), 108.8 (SCꢀC),
211.8 (CO). Anal. Calc. for C12H14O2SSiFe (Found): C,
47.07 (47.22); H, 4.61 (4.75)%.
Hydrogen atoms were introduced on calculated posi-
tions and refined riding on their carrier atoms. All
non-H atoms were refined with anisotropic thermal
parameters. A final Fourier map showed no residual
3.2. Reaction of [(p5-C5H5)Fe(CO)2(SCꢀCSiMe3)] with
[Co2(CO)8]
density outside −0.244 and 0.200 e A−3. The absolute
,
configuration of the compound 2 has been determined
on the basis of refinement of Flack’s parameter X [14],
which is the fractional contribution of F(−h) like it is
showed in the following formula: F(h)=(1−X)F(h)+
XF(−h). The value of this parameter was found close
to 0 [−0.001(13)], that proves the adequate choice of
the enantiomer. The drawing of molecule has been
performed with the program ZORTEP [15] with 50%
probability displacement ellipsoids for non-hydrogen
atoms.
[Co2(CO)8] (0.08 g, 0.23 mmol) dissolved in THF (15
ml) was added to a solution of 2 (0.07 g, 0.23 mmol) in
the same solvent (15 ml). The mixture was stirred at
20 °C for 1 h. After evaporation of the solvent to
dryness the solid residue was chromatographed on silica
gel 100. Compound 3 was eluted from a mixture of
n-hexane–THF (10:1) as a green band. Recrystalliza-
tion from n-hexane at −76 °C afforded a green solid
(0.107 g, 72.0% yield). IR (cm−1, hexane): 2080 (m),
2046 (s), 2036 (m), 2018 (m), 2012 (m), 2005 (sh), 1995
(m), 1984 (w), 1962 (w).1H-NMR (CDCl3): at 20 °C, l
(ppm) 0.37 [s, 9H, Si(CH3)3], 5.10 [s, 9H, C5H5].
5. Supplementary material
13C{1H}-NMR (CDCl3): at 20 °C,
l
(ppm) 0.5
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 155925 for compound 2.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[Si(CH3)3], 85.5 (C5H5), 93.9, 128.2 (CꢀC), 200.7
(CoꢁCO), 212.4 (FeꢁCO). FAB+ (m/z): 593 (M++1),
564 (M+−CO), 536 (M+−2CO), 508 (M+−3CO),
480 (M+−4CO), 452 (M+−5CO), 424 (M+−6CO),
396 (M+−7CO), 368 (M+−8CO). Anal. Calc. for
C18H14O8SSiFeCo2 (Found): C, 36.51 (36.92); H, 2.38
(2.80)%.
4. Crystal data for 2
Acknowledgements
Light yellow crystals of 2 suitable for an X-ray study
were obtained upon standing a solution overnight in
n-hexane at −20 °C (0.40×0.40×0.20 mm). Com-
pound 2 of formula C12H14O2SSiFe crystallizes in the
Financial support was generously provided by the
Direccio´n General de Investigacio´n Cient´ıfica y Te´c-
nica, Spain (Project PB97-0020).
orthorhombic cell of space group Pmn21, with a=
3
,
,
9.756(2), b=9.271(2), c=8.156(2) A, V=737.7(3) A ,
References
Z=4,
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Stoe Imaging Plate Diffraction System (IPDS),
equipped with an Oxford Cryosystems Cryostream
Cooler Device diffractometer and using a monochro-
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