Reactivity of Fe3(CO)12 towards thiols containing an α,β-unsaturated ketone system

Article abstract of DOI:10.1016/S0020-1693(03)00194-4

The unsaturated derivatives [Fe₂(CO)₆(μ-S₂C=CHC(O)C₆H ₄X)] (X=F, OMe) have been isolated by reaction of [(HS)₂C=CHC(O)C₆H₄X] (X=F, OMe) with Fe₃(CO)_12<

Full text of DOI:10.1016/S0020-1693(03)00194-4

Inorganica Chimica Acta 351 (2003) 119ꢂ122
/
www.elsevier.com/locate/ica
Reactivity of Fe3(CO)12 towards thiols containing an a,b-unsaturated
ketone system
Cecilio Alvarez-Toledano a, Esther Delgado b,*, Bruno Donnadieu c, Elisa Herna´ndez b,
Gema Mart´ın b, Fe´lix Zamora b
a Instituto de Qu´ımica-UNAM, Circuito Exterior, Ciudad Universitaria, Coyoaca´n, C.P. 04510, Me´xico D.F., Mexico
b Departamento de Qu´ımica Inorga´nica, Facultad de Ciencias, Universidad Auto´noma de Madrid, E 28049 Madrid, Spain
c Service de Cristallochimie, Laboratoire de Chimie de Coordination CNRS, 31077 Toulouse, France
Received 23 October 2002; accepted 22 January 2003
Abstract
The unsaturated derivatives [Fe2(CO)6(m-S2CÄ
CHC(O)C6H4X] (XꢀF, OMe) with Fe3(CO)12 in dried THF. Addition of Fe2(CO)9 to a solution of [Fe2(CO)6(m-S2CÄ
CHC(O)C6H4OMe)] affords [Fe(CO)4{m-(OMe)C6H4C(O)CHÄC(S)2Fe2(CO)6}]. The new compounds have been characterised by
/
CHC(O)C6H4X)] (Xꢀ
/
F, OMe) have been isolated by reaction of [(HS)2CÄ
/
/
/
/
analytical and spectroscopic data and the crystal structure of [Fe2(CO)6(m-S2CÄ/CHC(O)C6H4F)] has been solved by X-ray
diffraction.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Iron carbonyl; Thiolate; a,b-Unsaturated ketone
1. Introduction
in exploring the conditions to obtain the analogous
unsaturated derivatives.
Here, we report on the preparation of compounds
Iron carbonyl compounds containing a,b-unsaturated
ketone systems have been used as precursors in organic
syntheses [1]. However, reports on the co-ordination
chemistry of these ligands with transition metals are
[Fe2(CO)6(m-S2CÄ
/
CHC(O)C6H4X)] [Xꢀ
/
F (1a), OMe
C(S)2Fe2-
(1b)] and [Fe(CO)4{m-(OMe)C6H4C(O)CHÄ
/
(CO)6}] (2). They have been characterised by analytical
and spectroscopic data and the structure of 1a has been
confirmed by X-ray diffraction.
scarce [2], although of the presence of the CÃ
and CÃC double bond in these molecules may lead to a
wide reactivity.
/O ketone
/
On the other hand, the chemistry of SRꢁ ligands is
being widely developed due to their relevance in
bioinorganic chemistry as well as synthetic procedures
[3].
2. Experimental
2.1. General information
Taking in account all of these we have previously
carried out the reactions between Fe2(CO)9 and
All reactions were carried out under argon atmo-
sphere using Schlenk techniques. Solvents were dried
according to standard methods. IR spectra were re-
[(HS)2CÄ
the saturated compounds [Fe2(CO)6(m-S2CHCH2C(O)-
C6H4X)] (XꢀOMe, Br, Cl) [2a]. We are now interested
/CHC(O)C6H4X] which unfortunately gave
corded on a PerkinꢂElmer 1650 FTIR spectrophot-
/
/
1
ometer using NaCl cells. H NMR was registered on a
Bruker AMX-300 instrument in CDCl3. Elemental
analyses were performed on a PerkinꢂElmer 240-B
/
microanalyser. FAB mass spectra were carried out on
a WG AutoSpec spectrometer, using 3-nitrobenzyl
* Corresponding author. Tel.: ꢃ
4833.
E-mail address: esther.delgado@uam.es (E. Delgado).
/
34-91-397 5000; fax: ꢃ34-91-397
/
alcohol as matrix. The [(HS)2CÄ
/
CHC(O)C6H4X] (Xꢀ
/
0020-1693/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(03)00194-4

120
C. Alvarez-Toledano et al. / Inorganica Chimica Acta 351 (2003) 119ꢂ122
/
F, OMe) [4] and [3-(4-methoxyacetobenzophenyliden)-
5(4-methoxyacetobenzophenyl)-1,2,4-trithiole] [5], were
synthesised following literature methods.
2.3. Crystal data for complex 1a
Data collection were performed at 160 K on a Stoe
Imaging Plate Diffraction System (IPDS), equipped
with an Oxford Cryosystems Cryostream Cooler Device
and using a graphite-monochromated Mo Ka radiation
2.2. Preparations
˚
0.71073 A). Crystal data and structure refinement
(lꢀ
/
parameters for compound 1a are listed in Table 1.
Structure was solved by Direct Methods using SIR92
[6] and subsequent difference Fourier map techniques,
refined by least-squares procedures on a F2 by using
2.2.1. Synthesis of {Fe2(CO)6[(S)2CÄ
/
CHC(O)(C6H4X)]} (XꢀF (1a), OMe (1b))
/
To a solution of Fe3(CO)12 (0.360 g, 0.72 mmol) and
ONMe3 (0.054 g, 0.72 mmol) in dry THF (50 cm3),
(
SHELXL97) [7] included in the software WINGX [8], the
Atomic Scattering Factors were taken from Interna-
tional tables for X-ray crystallography [9] and a semi-
empirical corrections absorption have been applied to
the data [10]. All hydrogen atoms were located on a
difference Fourier map and refined by using a riding
model, except the atom H(2) connected to C(2) which
has been refined isotropically. All non-hydrogens atoms
were anisotropically refined, and in the last cycles of
refinement a weighting scheme was applied, where
weights have been calculated from the following for-
[(HS)2CÄ
cm3 of THF was slowly added. The resulting mixture,
which became brownꢂred immediately, was stirred for 1
/
CHC(O)C6H4X] (0.152 g, 0.72 mmol) in 10
/
h, then the solvent evaporated in vacuum to dryness and
the residue chromatographed on silica gel 100. Using n-
hexane as eluent a pink band of [Fe3(m-S)2(CO)9]
(traces) was obtained. Subsequent elution with a mixture
of n-hexane:THF (10:1) affords an orange band of
compound 1a (0.162 g, 45.3% yield). Details of the
synthesis of 1a also apply to 1b, however, the reaction
time in the former has been reduced to 5 min (37.5%
yield).
mula: wꢀ
/
1/[s2(Fo2)ꢃ(aP)2ꢃ
/
/
bP] where Pꢀ
/
(Fo2ꢃ2Fc2)/
/
3.
1a: IR (hexane, cmꢁ1): 2082 (m), 2046 (s), 2009 (s),
Drawing of molecules are performed by using the
program ORTEP32 [11] with 50% probability displace-
ment ellipsoids for non-hydrogen atoms.
1
1602 (w). H NMR: 7.85 (m, 2H, C6H4), 7.12 (m, 2H,
C6H4), 6.47 (s, 1H, CH). FABꢃ (m/z): 493 (Mꢃꢃ
1),
/
464 (Mꢃꢁ
/
CO), 437 (Mꢃꢃ
4CO), 352 (Mꢃꢁ
/
1ꢂ
/
2CO), 408 (Mꢃꢁ
/
3CO),
380 (Mꢃꢁ 5CO), 324 (Mꢃꢁ
Anal. Calc. for Fe2FS2O7C15H5 (Found): C, 36.62
/
/
/6CO).
(36.38); H, 1.02 (1.49)%.
1b: IR (hexane, cmꢁ1): 2080 (m), 2046 (s), 2008 (s),
1
1600 (w). H NMR: 7.85 (dd, 2H, C6H4), 6.95 (dd, 2H,
C6H4), 6.45 (s, 1H, CH), 3.90 (s, 3H, OCH3). FABꢃ (m/
Table 1
Crystallographic data of compound 1a
z): 505 (Mꢃꢃ
(Mꢃꢁ
(Mꢃꢁ
6CO). Anal. Calc. for Fe2S2O8C16H8 (Found): C,
38.12 (37.25); H, 1.63 (2.09)%.
/
1), 476 (Mꢃꢁ
/
CO), 448 (Mꢃꢁ
/
2CO), 420
/
3CO), 391 (Mꢃꢁ
/
4CO), 364 (Mꢃꢁ
/
5CO), 336
Formula
M
C
15H5FO7S2Fe2
492.01
0.50ꢄ0.30ꢄ0.15
/
Crystal size (mm)
Crystal form
Colour
/
/
parallelepiped
Dark red
monoclinic
Pbcn
Crystal system
Space group
2.2.2. Reaction of {Fe2(CO)6[(S)2CÄ
/
˚
a (A)
11.6300(9)
10.6063(6)
29.616(2)
3653.1(4)
8
CHC(O)(C6H4(OMe)]} with Fe2(CO)9
˚
b (A)
To a solution of compound 1b (0.058 g, 0.15 mmol) in
THF (10 cm3), Fe2(CO)9 (0.210 g, 0.85 mmol) was
added and the mixture stirred for 24 h. Then the solvent
was removed in vacuum and the residue chromato-
˚
c (A)
3
V (A )
˚
Z
Dcalc (g cmꢁ3
)
1.789
1.861
1952
m (mmꢁ1
F (000)
)
graphed on silica gel 100. Elution with n-hexaneꢂTHF
/
(20:1) afforded a orange band of compound 2 (0.016 g,
21.3% yield). IR (THF, cmꢁ1): 2077 (m), 2040 (s), 1998
(s), 1601 (w). 1H NMR: 7.89, 6.97 (AA?BB?, 4H, C6H4),
5.29 (s, 1H, CH), 3.88 (s, 3H, OCH3). FABꢃ (m/z): 672
2u Range (8)
3.3ꢂ52.1
27 479
3489
/
Reflections measured
Reflections unique
Rint
Goodness-of-fit on F2
0.0276
1.042
(Mꢃ), 504 (Mꢃꢁ
/
6CO), 448 (Mꢃꢁ
/
8CO), 420 (Mꢃ
Final R indices [I ꢀ
R indices (all data)
Largest difference peak and hole (e A
/
2s(I)]
R1ꢀ
R1ꢀ
0.327 and ꢁ
/
0.0206, wR2ꢀ
0.0266, wR2ꢀ
0.236
/
0.0499
ꢁ
/
9CO), 365 (Mꢃꢁ
This compound could not be characterised by elemental
/
9COÃ
/
Fe), 337 (Mꢃꢁ
/
10COÃFe).
/
/
/
0.0523
ꢁ3
˚
)
/
analyses due to its instability in solution.

C. Alvarez-Toledano et al. / Inorganica Chimica Acta 351 (2003) 119ꢂ
/122
121
Scheme 1.
1
In the H NMR spectra a singlet signal at d 6.47 (1a)
3. Results and discussion
and 6.45 ppm (1b) is assigned to the HCÄC group (6.90
/
We have recently described [2a] the syntheses of the
and 7.02 ppm, respectively, in the free ligand). A higher
chemical shift should be expected upon co-ordination of
the olefin [2b].
saturated
C6H4X)] (Xꢀ
Fe2(CO)9 and [(HS)2CÄ
derivatives
OMe, Br, Cl, Me) from the reaction of
CHC(O)C6H4X] in diethylether.
[Fe2(CO)6(m-S2CHCH2C(O)-
/
/
The molecular peak (m/z 493 and 505) of both
compounds is showed in the FABꢃ mass spectra. An
X-ray study on complex 1a was carried out to confirm
its structure (Fig. 1). Selected bond lengths and angles
are listed in Table 2. The molecule shows the two Fe
atom surrounded by three carbonyls and two sulfur
The formation of these compounds have been explained
in terms of a nucleophilic attack of HSC(S)CH2C(O)-
C6H4X (a tautomeric form of the dithiol) at the iron
carbonyl followed by CO elimination and hydrogen
migration from the SH to the CÄ
However, we have found that the unsaturated species
[Fe2(CO)6(m-S2CÄCHC(O)C6H4X)] [XꢀF (1a), OMe
(1b)] are formed as main compounds by reaction of
Fe3(CO)12 and [(HS)2CÄCHC(O)C6H4X] in dried THF
/C group.
atoms which together with the ironÃ
/
iron bond make a
Fe distance of
2.4872(3) A is similar to those found in analogous
derivatives [Fe2(CO)6(m-S2CHCH2C(O)C6H4X)] (Xꢀ
distorted octahedral geometry. The FeÃ
/
/
/
˚
/
/
˚
˚
OMe, Br, Cl) [2a] (2.478(3) A, Rꢀ
/
OMe; 2.477(17) A,
under argon atmosphere at room temperature, only if
the molar ratio Fe3(CO)12:ligand is 1:1 (Scheme 1).
Additional amounts of ligand produces a mixture of
compound 1 and the saturated species [Fe2(CO)6(m-
S2CHCH2C(O)C6H4X)], the former compound being
the only product isolated from the reaction when the
ratio Fe3(CO)12:ligand is increased up to 1:1.5. These
results indicate that an excess of iron carbonyl is
required to obtain compound 1. On the other hand, a
mechanism different from the above dealing with the
formation of the saturated derivatives has to take place
in this case. It has also been observed that the addition
of ONEt3 reduces the reaction time and increases the
yield. Compounds 1a or 1b are obtained from the
reaction after chromatographic workup and further
˚
Rꢀ
/
Br; 2.473(16) A, Rꢀ
/
Cl), [Fe2(CO)6(m-SEt)2]
˚
˚
(2.537(10) A) [12b], and [Fe2(CO)6(m-SPh)2] (2.516 A)
i
˚
[14] and [Fe2(CO)6(m-SC6H2Pr3)2] (2.466(2) A) [12c].
The FeÃ
two sulfur atoms. The C(1)Ã
is in agreement with a carbonÃ
therefore, the dithiolate ligand keeps unsaturated this
bond upon co-ordination to iron. The FeÃS distances as
well as the SÃFeÃS angle are in the range observed in
related complexes [2a,13]. The FeÃCÃO angles do not
deviate significantly from linearity.
C remaining in the compound 1b as well as the
/
Fe bond is almost symmetrically bridged by the
˚
/
C(2) distance of 1.328(2) A
/carbon double bond and,
/
/
/
/
/
The CÄ
/
presence of the ketone group in this molecule, prompted
us to increase its nuclearity by reaction of 1 with more
crystallisation from n-hexaneꢂ
/
THF at ꢁ20 8C.
/
The use of the [3-(4-methoxyacetobenzophenyliden)-
5(4-methoxyacetobenzophenyl)-1,2,4-trithiole] ligand,
under analogous reaction conditions produces the
rupture of the SÃ
/
S and SÃ
/
C bonds to yield compound
1b (Scheme 1).
The IR spectra of compounds 1a and 1b show a
n(CO) pattern similar to those exhibited for
[Fe2(CO)6(m-S2CHCH2C(O)C6H4X)] [2a] as well as the
analogous [Fe2(CO)6(m-L)2] [12] and [Fe2(CO)6(m-L)]
[13] which is indicative of the co-ordination of a
Fe2(CO)6 fragment to the sulfur atoms of the ligand.
Fig. 1. View of the molecular structure of compound 1a.

122
C. Alvarez-Toledano et al. / Inorganica Chimica Acta 351 (2003) 119ꢂ122
/
Table 2
References
˚
Selected bond lengths (A) and angles (8) for compound 1a
[1] (a) A.C. Reduto dos Rios, L.S. Hegedeus, Organometallics 14
(1995) 1586;
Bond lengths
Fe(1)Ã
Fe(1)Ã
Fe(1)Ã
Fe(2)Ã
/
Fe(2)
S(1)
S(2)
S(1)
2.4872(3)
2.2691(5)
2.2703(5)
2.2816(5)
Fe(2)Ã
C(1)ÃC(2)
S(1)Ã
S(2)Ã
/
S(2)
2.2669(5)
1.328(2)
1.778(2)
1.771(2)
(b) L.S. Hegedeus, R. Inwinkel-Reid, M. Alarid-Sargent, D.
Dorak, Y. Saton, J. Am. Chem. Soc. 112 (1990) 1109;
(c) S.E. Gibson, G.J. Tustin, J. Chem. Soc., Perkin Trans. (1995)
2427.;
/
/
/
/
C(1)
C(1)
/
/
(d) R.S. Tanke, R.H. Crabtree, Tetrahedron Lett. 29 (1988) 6737;
(e) O. Garc´ıa-Mellado, R. Gutie´rrez-Pe´rez, C. Alvarez-Toledano,
R.A. Toscano, A. Cabrera, Polyhedron 16 (1997) 2979.
Bond angles
S(1)ÃFe(1)Ã
S(2)ÃC(1)ÃS(1)
C(2)ÃC(1)ÃS(2)
/
/
S(2)
73.32(2)
99.59(8)
127.7(1)
C(2)Ã
C(1)Ã
/
C(1)Ã
/
S(1)
132.6(1)
122.6(2)
/
/
/
C(2)Ã
/C(3)
[2] (a) C. Alvarez-Toledano, J. Enr´ıquez, R.A. Toscano, M. Mart´ı
/
/
-
nez-Garc´ıa, E. Corte´s-Corte´s, Y. Osornio, O. Garc´ıa, R. Gutie´r-
rez-Pe´rez, J. Organomet. Chem. 577 (1999) 38;
(b) F. Ortega-Jime´nez, M.C. Ortega-Alfaro, J.G. Lo´pez-Corte´s,
iron carbonyl. Thus, 1b was treated with Fe2(CO)9 (1:1
ratio) in THF to yield [Fe(CO)4{m-(OMe)C6H4C(O)-
R. Gutierrez-Pe´rez, R.A. Toscano, L. Velasco-Ibarra, E. Pena-
˜
Cabrera, C. Alvarez-Toledano, Organometallics 19 (2000) 4127;
(c) C. Alvarez-Toledano, R. Gutie´rrez-Pe´rez, R.A. Toscano, M.
Moya-Cabrera, T. Haquet, M.C. Ortega, A. Cabrera, Polyhedron
20 (2001) 215;
CHÄ
spectroscopic data. The Fe(CO)4 fragment co-ordinated
through the carbonÃcarbon double bond was inferred
from the 1H NMR spectrum. The signal assigned to the
HCÄC group that appears at 6.46 ppm in the starting
/C(S)2Fe2(CO)6}] (2) on the basis of analytical and
/
(d) C. Alvarez-Toledano, E. Delgado, B. Donnadieu, M.A.
Go´mez, E. Herna´ndez, G. Mart´ın, F. Ortega-Jime´nez, F. Zamora,
Eur. J. Inorg. Chem. (2003) 562.
/
[3] (a) R.J. Angelici, Polyhedron 16 (1997) 3073;
(b) C. Bianchini, A. Meli, Acc. Chem. Res. 31 (1998) 109;
(c) I.R. Wittall, A.M. McDonagh, M.G. Humphry, M. Samoc,
Adv. Organomet. Chem. 42 (1998) 291;
material is shifted to higher field (5.29 ppm) which is in
accordance with data reported by us for this type of
coordination [2b]. Additional information was obtained
from its FABꢃ mass spectrum where a good agreement
has been found between the observed and the calculated
molecular-ion peak (m/z 672). Attempts to crystallise 2
were unsuccessful due to the release of the Fe(CO)4
fragment in solution.
(d) C.D. Stout, in: T.G. Spiro (Ed.), Iron Sulfur Proteins (Chapter
3), Wiley, New York, 1982;
(e) W.E. Newton, in: R. Metselaar, H.J.M. Heiligers, J. Schoon-
man (Eds.), Studies in Inorganic Chemistry, vol. 5, Elsevier,
Amsterdam, 1984;
(f) D. Coucouvanis, Acc. Chem. Res. 14 (1981) 201.
[4] F.C.V. Larsson, S.O. Lawesson, Tetrahedron 28 (1972) 5341.
[5] O. Baldovino-Pantaleo´n, R. Gutie´rrez-Pe´rez, R.A. Toscano, M.
Moya-Cabrera, A. Cabrera, Y. Reyes-Ortega, C. Alvarez-Tole-
dano, Heteroatom. Chem. 11 (2000) 329.
[6] A. Altomare, G. Cascarano, G. Giacovazzo, A. Guagliardi, M.C.
Burla, G. Polidori, M. Camalli, J. Appl. Crystallogr. 27 (1994)
435.
4. Supplementary material
Crystallographic data for compound 1a has been
deposited with the Cambridge Crystallographic Data
Centre, CCDC no. 183658. Copies of this information
may be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
[7] G.M. Sheldrick, SHELXL97, in: Program for the Refinement of
Crystal Structures, University of Gottingen, Gottingen, Germany,
1998.
¨
¨
[8] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[9] International Tables for X-ray Crystallography, Kynoch Press,
Birmingham, vol. IV, 1974.
[10] N. Walker, D. Stuart, Acta Crystallogr., A 39 (1983) 158.
[11] L.J. Farrugia, J. Appl. Crystallogr. 30 (1997) 565.
[12] (a) G. Bor, J. Organomet. Chem. 94 (1975) 181;
(b) D. Seyferth, R.S. Henderson, L.-C. Song, Organometallics 1
(1982) 125;
(fax: ꢃ44-1223-336-033); e-mail: deposit@ccdc.cam.ac.
uk or www: http://www.ccdc.cam.ac.uk).
/
(c) L.F. Dahl, C.-H. Wei, Inorg. Chem. 2 (1963) 328;
(d) E. Delgado, E. Herna´ndez, N. Mansilla, F. Zamora, L.A.
Mart´ınez-Cruz, Inorg. Chim. Acta 284 (1999) 14.
[13] (a) M.M. Hasan, M.B. Hursthouse, S.E. Kabir, K.M.A. Malik,
Polyhedron 20 (2001) 97;
Acknowledgements
Financial support was generously provided by the
Direccio´n General de Investigacio´n, Spain (Project BQU
2001/0216).
(b) J.A. Cabeza, M.A. Martinez-Garc´ıa, V. Riera, D. Ardura, S.
Garc´ıa-Granda, Organometallics 17 (1998) 1471.
[14] W. Henslee, R.E. Davis, Cryst. Struct. Commun. 1 (1972) 403.