Iron dithiocarbonate complexes: Structure of CpFe(CO)2SC(S)O-4-C6H4Cl

Article abstract of DOI:10.1016/j.poly.2005.11.007

A group of dithiocarbonate iron complexes CpFe(CO)₂SC(S)OAr (1) were prepared by the reaction of (μ-S_x)[CpFe(CO)₂]₂ with arylchlorothionoformates (Ar = Ph (1a), 4-C₆H₄Cl (1b), 4-C₆H₄F (1c), C₆F₅ (1d), 4-C₆H₄CH₃ (1e)). The conversion of 1 into CpFe(CO)(κ²S,S-SC(S)OAr) (2), in which the dithiocarbonate ligand is bonded to the iron through the two S-atoms, can be achieved photolytically. The structure of CpFe(CO)₂SC(S)O-4-C₆H₄Cl (1b) is reported.

Full text of DOI:10.1016/j.poly.2005.11.007

Polyhedron 25 (2006) 1695–1699
www.elsevier.com/locate/poly
Iron dithiocarbonate complexes: Structure of
CpFe(CO)2SC(S)O-4-C6H4Cl
*
Mohammad El-khateeb , Khalil J. Asali, Anas Lataifeh
Chemistry Department, Jordan University of Science and Technology, Irbid 22110, Jordan
Received 26 October 2005; accepted 9 November 2005
Available online 22 December 2005
Abstract
A group of dithiocarbonate iron complexes CpFe(CO)2SC(S)OAr (1) were prepared by the reaction of (l-Sx)[CpFe(CO)2]2 with aryl-
chlorothionoformates (Ar = Ph (1a), 4-C6H4Cl (1b), 4-C6H4F (1c), C6F5 (1d), 4-C6H4CH3 (1e)). The conversion of 1 into
CpFe(CO)(j2S,S-SC(S)OAr) (2), in which the dithiocarbonate ligand is bonded to the iron through the two S-atoms, can be achieved
photolytically. The structure of CpFe(CO)2SC(S)O-4-C6H4Cl (1b) is reported.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Iron; Sulfur; Dithiocarbonate; Chelate; Complexes; X-ray structure
1. Introduction
of the iron chloride complex, CpFe(CO)2Cl, with sodium
dialkyldithiocarbamates in acetone gave CpFe(CO)2(jS-
S2CNR2) (R = Me, Et), which contains a unidentate
dialkyldithiocarbamates group [16,17]. The same products
were also obtained from the reaction of the iron dimer,
[CpFe(CO)2]2, amines (NHR2) and CS2 in refluxing THF,
or by concerted CS2 insertion into the Fe–N bond of the
[CpFe(CO)2(NHR2)]+ salt in the presence of a base [14].
The chelate complex CpFe(CO)(j2S,S-S2CNMe2) is
obtained from the reaction of the dimer with tetramethyl-
thiuram disulfide, [(CH3)2NCS2]2. The ethyl-dithiocarbon-
ate complexes Cp0Fe(CO)2(jS-S2COEt) (Cp0 = C5H5,
C5Me5) were prepared from the reaction of the correspond-
ing iron dimers [Cp0Fe(CO)2]2 with [EtOC(S)S]2 in
cyclohexane [18,19]. Photolysis of these complexes gave
Cp0Fe(CO)(j2S,S-S2COEt) which have a bidentate ligand.
Treatment of Cp0Fe(CO)2(jS-S2COEt) with phosphine or
phosphite ligands gave the mixed carbonyl-phosphine or
phosphite complexes Cp0Fe(CO)(L)(jS-S2COEt) (L =
PBu3, PPh3, P(OEt)3, P(OPh)3) [20]. The trithiocarbonate
complexes CpFe(CO)2(jS-S2CSR) have been prepared from
ꢀ
Dithioacid ligands, X–CS2 (X = OR, SR, NR2), have a
rich coordination and organometallic chemistry [1–3].
These ligands are obtained easily by the addition of the
nucleophiles (ROꢀ, RSꢀ, NHR2) to carbon disulfide
[4–10]. Dithioacid ligands and their metal complexes have
obtained continuous attraction due to their interesting
structural and chemical properties as well as their wide
range of application in biological systems [11–13].
Transition metal complexes with dithioacid ligands are
very common in the literature [4–16]. They have been gen-
erally prepared by metatheses reaction of transition metal
halides with the free ligands. In most cases the ligand is
bonded to the metal in a chelate fashion through the two
S-atoms. However, several complexes in which the mode
of coordination of the dithioacid ligands is monodentate
were obtained and characterized [14,15].
A variety of complexes containing dithioacid ligands with
cyclopentadienyl iron system has been reported. Treatment
ꢀ
CpFe(CO)2Cl and the in situ generated anions RSCS2
*
Corresponding author. Tel.: +962 2 7201000x23644; fax: +962 2
(R = Me, Et, Ph). These complexes can be converted to the
7095014.
chelated form, CpFe(CO)(j2S,S-S2CSR) by photolysis [21].
E-mail address: kateeb@just.edu.jo (M. El-khateeb).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.11.007

1696
M. El-khateeb et al. / Polyhedron 25 (2006) 1695–1699
In the framework of synthetic studies of cyclopentadie-
When a THF solution containing CpFe(CO)2SCSOAr
(1) was irradiated by UV-light for short time (ca.
30 min), the chelate complexes CpFe(CO)(j2S,S-S2COAr)
(2) were obtained in high yields (Eq. (2)).
nyl iron sulfur complexes, we have studied the reactions
of the iron sulfides (l-Sx)[CpFe(CO)2]2 with a variety of
nucleophiles such as acid chlorides, sulfonyl chlorides
and chloroformates. These reactions give the sulfur con-
taining complexes, thiocarboxylates (CpFe(CO)2SCOR)
[22–24], thiosulfonates (CpFe(CO)2SSO2R) [25] and thio-
carbonates (CpFe(CO)2SCO2R) [26]. We hereby report
the synthesis of dithiocarbonate complexes of iron by the
reaction of the iron sulfides, (l-Sx)[CpFe(CO)2]2, with aryl
chlorothionoformates.
S
hν
Fe
Ar
Fe
S
CO
+
ð2Þ
S
O
S
OC
OC
CO
OAr
1
2
Compounds 2 were characterized by IR, 1H NMR
spectroscopy and elemental analysis. The IR spectrum
of each of complexes 2 in the carbonyl stretching region
exhibits a singlet band in the range 1953–1961 cmꢀ1 for
the terminal carbonyl group coordinated to the iron cen-
ter. This range is comparable to those found for iron
complexes containing one CO-group such as CpFe-
(CO)(EPh3)SCOR (1950–1970 cmꢀ1). 1H NMR spectra
of 2 in CDCl3 show singlet peak in the range 4.63–
4.69 ppm for the cyclopentadienyl protons. This peak
has lower chemical shift compared to the corresponding
peak of the starting dicarbonyl complexes 1. This shift
may attributed to the higher electron-density around the
Fe-atom in 2 compared to that in 1. Comparing this peak
to that of CpFe(CO)(EPh3)SCOR, it is obvious that these
values are comparable to each other.
2. Results and discussion
2.1. Synthesis and characterization
The reaction of (l-Sx)[CpFe(CO)2]2 with various aryl
chlorothionoformates proceeds smoothly to give the corre-
sponding dithiocarbonate complexes CpFe(CO)2SC(S)OAr
(1) as shown in Eq. (1). The iron chloride, CpFe(CO)2Cl is
obtained as a by-product of this reaction and can be sepa-
rated from the products 1 by column chromatography.
CO
S
CO
Ar
Fe
Fe Sx
CO
+
Cl
O
OC
2.2. Crystal structure
ð1Þ
The structure of CpFe(CO)2SC(S)O-4-C6H4Cl (1b) was
determined by single-crystal X-ray analysis and is shown
in Fig. 1. Selected bond lengths and angles are shown in
Table 1. The relevant bond parameters are listed in Table
2. As expected, the analysis proved that the dithiocarbon-
ate ligand is bonded to the iron in a monodentate fashion
through one sulfur atom with an Fe–S bond distance of
S
Fe
CO
Ar
Fe
+
S
O
Cl
OC
OC
CO
1
Ar = Ph (a), 4-C6H4Cl (b), 4-C6H4F (c), C6F5 (d), 4-
C6H4CH3 (e)
˚
2.2765(5) A. This distance is longer than the corresponding
The new organoiron S-bonded dithiocarbonates (1)
are stable solids and are also stable in solution. Struc-
tural features of 1 were identified on the basis of IR
and H NMR spectroscopy as well as by elemental anal-
ysis. The IR spectra of 1 in the carbonyl stretching
˚
Fe–S distance in CpFe(CO)2SCO2Et (2.2675(10) A) and in
˚
CpFe(CO)2SCO-2-C6H4NO2 (2.266(1) A) The Cp ligand is
bound to the metal in an g5-fashion with Fe–C bond dis-
tances comparable to those observed for Cp–iron com-
plexes. The Fe–C (of carbonyl ligands) bond distances of
1
region show two bands due to the terminal carbonyl
groups in the ranges 2044–2049 and 1998–2006 cmꢀ1
.
˚
1.7745(19) and 1.7810(17) A are in the normal range for
CpFe(CO)2X complexes [24,26–28]. The Fe–S1–C8 angle
is 113.50ꢁ.
These bands are higher than those reported for the cor-
responding thiocarboxylates CpFe(CO)2SCOR (2027–
2060, 1984–1998 cmꢀ1) [22–24] and are similar to those
of thiocarbonate complexes CpFe(CO)2SCO2R (2044–
2045 and 1997–1999 cmꢀ1) [26], suggesting that the
mono- and di-thiocarbonate ligands have similar basicity.
3. Experimental
3.1. General
1
In the H NMR spectra of 1, the peak for the Cp-pro-
tons is found in the range 5.05–5.10 ppm. This chemical
shift range is similar to that observed for the thiocarb-
oxylate (4.98–5.13 ppm) [22–24] and thiocarbonate
(4.98–5.12 ppm) analogues [26]. These results suggest a
similar electron density around the iron center in all of
these complexes.
All reactions were carried out under an inert atmosphere
of nitrogen using standard Schlenk line techniques.
Solvents were dried by standard methods and were distilled
under nitrogen prior to use. The complexes (l-Sx)-
[CpFe(CO)2]2 (x = 2, 3) were prepared by published
method [29]. The reagents: aryl-chlorothionoformates,

M. El-khateeb et al. / Polyhedron 25 (2006) 1695–1699
1697
Fig. 1. ORTEP drawing of CpFe(CO)2SC(S)O-4-C6H4Cl (1b).
Table 1
Table 2
˚
Selected bond length (A) and angles (ꢁ) of CpFe(CO)2SC(S)O-4-C6H4Cl
(1b)
Selected crystal data and refinement parameters for CpFe(CO)2SC(S)O-4-
C6H4Cl (1b)
Fe–S1
Fe–C1
Fe–C2
Fe–C3
Fe–C4
Fe–C5
Fe–C6
Fe–C7
S1–C8
S2–C8
C1–O1
C2–O2
C3–O3
C9–O3
2.2765(5)
1.77745(19)
1.7810(17)
2.0785(19)
2.1003(19)
2.110(2)
C8–S1–Fe
C1–Fe–S1
C2–Fe–S1
C2–Fe–C1
C8–O3–C9
O3–C8–S2
O3–C8–S1
S1–C8–S2
113.50(5)
89.25(6)
94.92(5)
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
Unit cell dimensions
C14H9ClFeO3S2
380.63
0.13 · 0.10 · 0.08
monoclinic
P21/c
92.24(9)
120.75(12)
124.53(11)
114.36(11)
121.10(9)
˚
2.089(2)
a (A)
11.4680 (10)
9.7400 (10)
13.678 (10)
90.00
103.21(5)
90.00
˚
2.0818(19)
1.7095(16)
1.6541(15)
1.139(2)
1.139(2)
1.3553(18)
1.4036(18)
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
1487.4 (2)
4
Z
Index ranges
ꢀ16 6 h 6 9,
0 6 k 6 13, 0 6 l 6 19
4334
Number of total reflections
Number of unique
[CpFe(CO)2]2, and sulfur were obtained from Acros and
were used as received.
3711
reflections (>2r(I))
Nuclear magnetic resonance (NMR) spectra were
recorded on a Bruker 200 MHz spectrometer. Chemical
shifts are in ppm relative to TMS at 0 ppm. Infrared (IR)
spectra were recorded on a Nicolat Nexus FT-IR spec-
trometer using NaCl solvent cells. Elemental analyses were
Dcalc (Mg mꢀ3
)
1.855
Mo Ka
1.478
0.71069
1.82–30.05
0.0280
0.0765
Radiation type
l (mmꢀ1
k (A)
)
˚
h Range (ꢁ)
R[F2 > 2r(F2)]
xR(F2)a
a
´
´
done in Laboratoire dÕAnalyse Elementaire, Universite de
´
´
Montreal, Montreal, Que., Canada. Melting points were
reported on an electrothermal melting point apparatus
and are uncorrected. The photolytic reactions were carried
out in a medium pressure mercury lamp (150 W) with a
quartz immersion cell.
2
x ¼ 1=½r2ðF o2Þ þ ð0:0426PÞ ꢁ; where P ¼ ðF o2 þ 2F 2c Þ=3.
eluted with hexane to remove any unreacted aryl chloroth-
ionoformates. Then, it was eluted with hexane/dichloro-
methane solution (1:1 v:v ratio) to give a red-orange band
which was collected and identified as CpFe(CO)2SC(S)OAr,
followed by a red band which was also collected and identi-
fied as CpFe(CO)2Cl. The CpFe(CO)2SC(S)OAr (1) were
recrystallized from dichloromethane/hexane.
3.2. General procedure for the preparation of
CpFe(CO)2SC(S)OAr (1)
To a solution of (l-Sx)[CpFe(CO)2]2 (0.50 mmol) in
diethylether (100 mL), aryl chlorothionoformate (0.55
mmol) was added and the resulting mixture was stirred over-
night at room temperature. The volatiles were removed
under reduced pressure and the resulting solid was redis-
solved in a minimum amount of CH2Cl2 and transferred to
a silica gel column made up in hexane. The column was first
3.2.1. CpFe(CO)2SC(S)OC6H5 (1a)
Yield, 79%; m.p. 132–133 ꢁC. Anal. Required for
C14H10FeO3S2: C, 48.57; H, 2.91; S, 18.53. Found: C,
47.78; H, 2.65; S, 18.03%. IR (CH2Cl2, cmꢀ1): 2045s,

1698
M. El-khateeb et al. / Polyhedron 25 (2006) 1695–1699
1
1998s m(C„O). H NMR (CDCl3, d, ppm): 5.05 (s, 5H,
46.12; H, 2.29; S, 18.56%. IR (CH2Cl2, cmꢀ1): 1956s
m(C„O). H NMR (CDCl3, d, ppm): 4.67 (s, 5H, C5H5),
1
C5H5), 7.07 (m, 3H, C6H5), 7.31 (m, 2H, C6H5).
7.19 (d, 2H, C6H4), 7.40 (d, 2H, C6H4).
3.2.2. CpFe(CO)2SC(S)O-4-C6H4Cl (1b)
Yield, 87%; m.p. 134–136 ꢁC. Anal. Required for
C14H9ClFeO3S2: C, 44.18; H, 2.38; S, 16.58. Found: C,
44.10; H, 2.23; S, 15.98%. IR (CH2Cl2, cmꢀ1): 2046s,
3.3.4. CpFe(CO)(j2S,S-SC(S)OC6F5) (2d)
Yield, 87%; m.p. 78–79 ꢁC. Anal. Calc. for
C13H5F5FeO2S2: C, 38.25; H, 1.23; S, 15.71. Found: C,
37.90; H, 1.11; S, 15.07%. IR (CH2Cl2, cmꢀ1): 1961s
1
1999s m(C„O). H NMR (CDCl3, d, ppm): 5.05 (s, 5H,
1
C5H5), 6.95 (d, 2H, C6H4), 7.32 (d, 2H, C6H4).
m(C„O). H NMR (CDCl3, d, ppm): 4.69 (s, HÕs, C5H5).
3.2.3. CpFe(CO)2SC(S)O-4-C6H4F (1c)
3.3.5. CpFe(CO)(j2S,S-SC(S)O-4-C6H4Me) (2e)
Yield, 75%; m.p. 95–96 ꢁC. Anal. Required for
C14H12FeO2S2: C, 50.61; H, 3.64; S, 19.30. Found: C,
50.31; H, 3.78; S, 19.50%. IR (CH2Cl2, cmꢀ1): 1953s
Yield, 86%; m.p. 128–129 ꢁC. Anal. Required for
C14H9FFeO3S2: C, 46.17; H, 2.49; S, 17.61. Found: C,
45.88; H, 2.28; S, 17.01%. IR (CH2Cl2, cmꢀ1): 2046s,
1
1
2000s m(C„O). H NMR (CDCl3, d, ppm): 5.09 (s, 5H,
m(C„O). H NMR (CDCl3, d, ppm): 2.33 (s, 3H, CH3),
C5H5), 7.00 (d, 2H, C6H4), 7.40 (d, 2H, C6H4).
4.63 (s, 5H, C5H5); 6.97 (d, 2H, C6H4), 7.17 (d, 2H, C6H4).
3.2.4. CpFe(CO)2SC(S)OC6F5 (1d)
3.4. X-ray structure analysis
Yield, 90%; m.p. 115–116 ꢁC. Anal. Required for
C14H5F5FeO3S2: C, 38.55; H, 1.16; S, 14.70. Found: C,
38.22; H, 0.99; S, 14.13%. IR (CH2Cl2, cmꢀ1): 2049s, 2006s
m(C„O). 1H NMR (CDCl3, d, ppm): 5.10 (s, HÕs, C5H5).
Crystals suitable for X-ray diffraction of 1b were obtained
from CH2Cl2/hexane mixture. The data were collected on a
KappaCCD diffractometer with graphite monochromated
Mo Ka radiation at 175 K. The crystallographic data are
shown in Table 2. The cell parameters were determined from
4335 reflections collected in the range 1.82 6 h 6 30.05ꢁ.
There were 4334 independent reflections with 3711 observed
reflections (>2r(I)). The structure was solved by direct
method using SHELXS-97 [30] and DIFMAP synthesis using
SHELXTL-96 [31].
3.2.5. CpFe(CO)2SC(S)O-4-C6H4Me (1e)
Yield, 85%; m.p. 138–140 ꢁC. Anal. Required for
C15H12FeO3S2: C, 50.01; H, 3.24; S, 17.58. Found: C,
49.79; H, 3.36; S, 17.58%. IR (CH2Cl2, cmꢀ1): 2044s, 2000s
1
m(C„O). H NMR (CDCl3, d, ppm): 2.31 (s, 3H, CH3),
5.05 (s, 5H, C5H5), 6.91 (d, 2H, C6H4), 7.22 (d, 2H, C6H4).
3.3. General procedure for the preparation of
CpFe(CO)(j2S,S-SC(S)OAr) (2)
4. Supplementary data
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 277850 for compound 1b. Cop-
ies of this information may be obtained free of charge
from The Director, CCDC, 12 Union Road, Cambridge,
CB2 1EZ, UK (fax: +44 1233 336 033; e-mail: deposit@
ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).
A THF solution (30 mL) of CpFe(CO)2SC(S)OAr
(0.25 mmol) was irradiated under a stream of N2 for
30 min. The products were separated by column chroma-
tography. The column was eluted with (2:1 v:v ratio)
CH2Cl2/hexane to separate the products which were recrys-
tallized from dichloromethane/hexane.
3.3.1. CpFe(CO)(j2S,S-SC(S)OC6H5) (2a)
Yield, 80%; m.p. 89–91 ꢁC. Anal. Required for
C13H10FeO2S2: C, 49.07; H, 3.17; S, 20.16. Found: C,
48.51; H, 3.11; S, 19.77%. IR (CH2Cl2, cmꢀ1): 1954s
m(C„O). H NMR (CDCl3, d, ppm): 4.65 (s, 5H, C5H5),
7.41 (m, 5H, C6H5).
Acknowledgments
The financial support (Grant No. 31/2002) from the
Deanship of Scientific Research, Jordan University of Sci-
ence and Technology is greatfully acknowledged. We thank
Prof. Richard Welter (University of Strasburg, France) for
determining the X-ray structure.
1
3.3.2. CpFe(CO)(j2S,S-SC(S)O-4-C6H4Cl) (2b)
Yield, 82%; m.p. 102–103 ꢁC. Anal. Required for
C13H9ClFeO2S2: C, 44.28; H, 2.57; S, 18.19. Found: C,
44.01; H, 2.54; S, 17.50%. IR (CH2Cl2, cmꢀ1): 1956s
m(C„O). H NMR (CDCl3, d, ppm): 4.66 (s, 5H, C5H5),
7.09 (d, 2H, C6H4), 7.37 (d, 2H, C6H4).
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