Selenothiocarbonate complexes of iron: Structure of CpFe(CO) 2SeC(S)O-4-C6H4Cl

Article abstract of DOI:10.1016/j.poly.2005.09.024

Stable complexes of general formula CpFe(CO)₂SeC(S)OR, where R = Ph (1a), 4-C₆H₄Cl (1b), 4-C₆H₄F (1c), C₆F₅ (1d), 4-C₆H₄CH ₃ (1e), were prepared by the reaction of (μ-Se)[CpFe(CO) ₂]₂ with ROC(S)Cl at room temperature. When a THF solution of 1 was photolyzed the chelate complexes CpFe(CO)(κ²Se,S- SeC(S)OR) (2) were obtained in good yields. All of these complexes have been characterized by elemental analyses, IR and ¹H NMR spectroscopy. The structure of CpFe(CO)₂SeC(S)O-4-C₆H₄Cl (1b) is reported.

Full text of DOI:10.1016/j.poly.2005.09.024

Polyhedron 25 (2006) 1386–1390
www.elsevier.com/locate/poly
Selenothiocarbonate complexes of iron: Structure of
CpFe(CO)2SeC(S)O-4-C6H4Cl
*
Mohammad El-khateeb
Chemistry Department, Jordan University of Science and Technology, Irbid 22110, Jordan
Received 10 August 2005; accepted 27 September 2005
Available online 7 November 2005
Abstract
Stable complexes of general formula CpFe(CO)2SeC(S)OR, where R = Ph (1a), 4-C6H4Cl (1b), 4-C6H4F (1c), C6F5 (1d), 4-C6H4CH3
(1e), were prepared by the reaction of (l-Se)[CpFe(CO)2]2 with ROC(S)Cl at room temperature. When a THF solution of 1 was photo-
lyzed the chelate complexes CpFe(CO)(j2Se,S-SeC(S)OR) (2) were obtained in good yields. All of these complexes have been character-
1
ized by elemental analyses, IR and H NMR spectroscopy. The structure of CpFe(CO)2SeC(S)O-4-C6H4Cl (1b) is reported.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Complexes; Iron; Selenium; Selenothiocarbonate; Structure; Chlorothionoformates
1. Introduction
of elemental selenium into the M–M bonds of the dimers
[CpM(CO)2]2 gave (l-Sex)[CpM(CO)2]2 (M = Fe, x = 1;
M = Ru, x = 5) [23–25]. The Cp-substituted Cr-dimers
[Cp0Cr(CO)3]2 (Cp0 = C5H4Me, C5H4COMe, C5H4CO2Me)
react with one equivalent of selenium to give the linear com-
plexes (l-Se)[Cp0Cr(CO)2]2 which contain two Cr–Se triple
bonds. These linear complexes react with another equivalent
of selenium to give the butterfly complexes (l,j2Se,
Se-Se2)[Cp0Cr(CO)2]2 [26,27]. Tungsten selenides (l-Sem)-
[CpW(CO)3]2 (m = 2, 3, 4) have been prepared by the reac-
tion of the anion CpW(CO)3Li with elemental selenium
followed by oxidation of the resulting inserted products
(CpW(CO)3SenLi) [28].
Our investigation showed that the iron selenide complex,
(l-Se)[CpFe(CO)2]2, which contains two lone pairs of elec-
trons around the selenium atom, is useful in the syntheses
of several iron selenium complexes. Selenocarboxylates
(CpFe(CO)2SeCOR) [23] and selenosulfonates (CpFe(CO)2-
SeSO2R) [29] have been synthesized by the reaction of this
iron selenide with acid- or sulfonyl-chlorides, respectively.
Photolytic reactions of the selenocarboxylate complexes
with EPh3 ligands (E = P, As, Sb) gave the CO-substituted
products of the general formula CpFe(CO)(EPh3)SeCOR
[30]. More recently, iron selenocarbonate complexes,
CpFe(CO)2SeCO2R, have also been prepared by treatment
Considerable interest in organometallic complexes con-
taining selenium ligands is promoted by their potential
applications in areas such as material science [1–6], cataly-
sis [7–10], electronic industry [11–13], and biochemistry
[14–18]. Recently, some of these complexes have been used
as precursors for the synthesis of metal selenides which are
used in electronic devices [7–13]. Moreover, selenium has
been found in a number of proteins and enzymes [14–18].
One class of hydrogenases is known to contain iron, nickel
and selenium atoms. The enzyme isolated from Desul-
fourbno baculatus is a representative of this class of en-
zymes. X-ray absorption spectroscopy and EPR studies
of this enzyme indicated that the Ni-atom is bonded to
3–4 nitrogen or oxygen atoms, 1–2 sulfur or chlorine atoms
and one selenium atom of a selenocysteine residue [19–22].
Several transition metal polyselenide complexes have
been reported in the literature. Insertion of elemental sele-
nium into metal–metal bonds represents a successful route
for the synthesis of such complexes. In this context, insertion
*
Tel.: +962 2 7201000x23644; fax: +962 2 7095014.
E-mail address: kateeb@just.edu.jo.
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.09.024

M. El-khateeb / Polyhedron 25 (2006) 1386–1390
1387
of (l-Se)[CpFe(CO)2]2 with alkyl or aryl chloroformates
[31].
(CH2Cl2, cmꢀ1) mCO 2037s, 1992s. Calc. for C14H9ClFeO3
SSe: C, 39.33; H, 2.12; S, 7.50. Found: C, 39.02; H, 1.96;
S, 7.00%.
Based on our previous reactions of the iron selenide with
electrophiles [29–31] this paper describes its reaction with
chlorothionoformates (ROC(S)Cl). This reaction was found
to give the expected selenothiocarbonates, CpFe(CO)2SeC-
(S)OR. These complexes can be converted to the chelated
complexes CpFe(CO)(j2Se,S-SeC(S)OR) upon photolysis.
2.1.3. [CpFe(CO)2SeC(S)O-4-C6H4F] (1c)
1
Yield: 80%. m.p. 136–137 ꢁC. H NMR (CDCl3) d 5.06
(s, 5H, C5H5); 7.06 (d, 2H, C6H4); 7.20 (d, 2H, C6H4). IR
(CH2Cl2, cmꢀ1) mCO 2036s, 1991s. Calc. for C14H9FFeO3
SSe: C, 40.90; H, 2.21; S, 7.80. Found: C, 39.98; H, 2.18;
S, 7.11%.
2. Experimental
All manipulations were performed under an inert atmo-
sphere of nitrogen using standard Schlenk line techniques.
Diethyl ether, hexane and benzene were distilled from so-
dium/benzophenone ketyl under nitrogen. Dichlorometh-
ane was refluxed over P2O5 and distilled under nitrogen.
The complex (l-Se)[CpFe(CO)2]2 was prepared by litera-
ture method [23]. The reagents: chlorothionoformates, iron
dimer [CpFe(CO)2]2, and selenium were obtained from
Acros and were used as received.
Nuclear magnetic resonance (NMR) spectra were re-
corded 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 spectrometer using
NaCl solvent cells. Elemental analyses were done in Labora-
2.1.4. [CpFe(CO)2SeC(S)OC6F5] (1d)
1
Yield: 87%. m.p. 133–134 ꢁC. H NMR (CDCl3) d 5.08
(s, HÕs, C5H5). IR (CH2Cl2, cmꢀ1) mCO 2041s, 1997s. Calc.
for C14H5F5FeO3SSe: C, 34.81; H, 1.04; S 6.64. Found: C,
34.34; H, 1.08; S, 5.98%.
2.1.5. [CpFe(CO)2SeC(S)O-4-C6H4Me] (1e)
1
Yield: 89%. m.p. 148–149 ꢁC. H NMR (CDCl3) d 2.33
(s, 3H, CH3); 5.03 (s, 5H, C5H5); 6.93 (d, 2H, C6H4); 7.22
(d, 2H, C6H4). IR (CH2Cl2, cmꢀ1) mCO 2036s, 1991s. Calc.
for C15H12FeO3SSe: C, 44.25; H, 2.97; S, 7.88. Found: C,
44.46; H, 2.77; S, 7.50%.
2.2. General procedure for the preparation of
CpFe(CO)(j2Se,S-SeC(S)OR) (2)
´
´
´
toire dÕAnalyse Elementaire, Universite de Montreal, Mon-
´
treal, Que., Canada. Melting points were reported on a
Staurt Melting point apparatus (SMP3) andare uncorrected.
The photolytic reactions were carried out in a medium pres-
sure mercury lamp (150 W) with a quartz immersion cell.
A THF solution (30 mL) of CpFe(CO)2SeC(S)OR
(0.25 mmol) was irradiated under a stream of N2 for
30 min. The volatiles were removed by vacuum and the
resulting solid was dissolved in a minimum amount of
dichloromethane and transferred to a silica gel column.
The column was eluted with CH2Cl2/hexane (1:2 v:v ratio)
to separate the products as an orange-brown band which
were recrystallized from hexane.
2.1. General procedure for the preparation of
CpFe(CO)2SeC(S)OR (1)
The complex (l-Se)[CpFe(CO)2]2 (0.22 g, 0.50 mmol) dis-
solved in diethyl ether (70 mL) was stirred under N2 and
chlorothionoformate (0.55 mmol) was added. After stirring
overnight, the volatiles were removed under reduced pres-
sure and the resulting solid was redissolved in a minimum
amount of CH2Cl2 and introduced to a silica gel column
made up in hexane. Elution with hexane removes the unre-
acted chlorothionoformates. Elution with hexane/dichloro-
methane solution (1:1 v:v ratio) gave a red-brown band
which was collected and identified as CpFe(CO)2SeC(S)OR,
followed by a red band which was also collected and identi-
fied as CpFe(CO)2Cl. The CpFe(CO)2SeC(S)OR were
recrystallized from dichloromethane/hexane.
2.2.1. [CpFe(CO)(j2Se,S-SeC(S)OC6H5)] (2a)
1
Yield: 85%. m.p. 102–103 ꢁC. H NMR (CDCl3) d 4.65
(s, 5H, C5H5); 7.10 (m, 5H, C6H5). IR (CH2Cl2, cmꢀ1) mCO
1954s. Calc. for C13H10FeO2SSe: C, 42.77; H, 2.76; S 8.78.
Found: C, 42.54; H, 2.66; S, 8.47%.
2.2.2. [CpFe(CO)(j2Se,S-SeC(S)O-4-C6H4Cl)] (2b)
Yield: 90%. m.p. 79–80 ꢁC. 1H NMR (CDCl3) d 4.65 (s,
5H, C5H5); 7.07 (d, 2H, C6H4); 7.35 (d, 2H, C6H4). IR
(CH2Cl2, cmꢀ1) mCO 1947s. Calc. for C13H9ClFeO2SSe: C,
39.08; H, 2.27; S, 8.03. Found: C, 39.60; H, 2.47; S, 7.38%.
2.1.1. [CpFe(CO)2SeC(S)OC6H5] (1a)
1
2.2.3. [CpFe(CO)(j2Se,S-SeC(S)O-4-C6H4F)] (2c)
Yield: 78%. m.p. 95–96 ꢁC. 1H NMR (CDCl3) d 4.65 (s,
5H, C5H5); 7.11 (d, 2H, C6H4); 7.25 (d, 2H, C6H4). IR
(CH2Cl2, cmꢀ1) mCO 1952s. Calc. for C13H9FFeO2SSe: C,
40.77; H, 2.37; S, 8.37. Found: C, 40.34; H, 2.09; S, 7.95%.
Yield: 72%. m.p. 159–160 ꢁC. H NMR (CDCl3) d 4.95
(s, 5H, C5H5); 7.41 (m, 5H, C6H5). IR (CH2Cl2, cmꢀ1) mCO
2035s, 1985s. Calc. for C14H10FeO3SSe: C, 42.78; H, 2.56;
S, 8.16. Found: C, 42.70; H, 2.44; S, 7.88%.
2.1.2. [CpFe(CO)2SeC(S)O-4-C6H4Cl] (1b)
Yield: 82%. m.p. 99–100 ꢁC. 1H NMR (CDCl3) d 5.06 (s,
5H, C5H5); 7.02 (d, 2H, C6H4); 7.37 (d, 2H, C6H4). IR
2.2.4. [CpFe(CO)(j2Se,S-SeC(S)OC6F5)] (2d)
Yield: 65%. m.p. 72–73 ꢁC. 1H NMR (CDCl3) d 4.69 (s,
HÕs, C5H5). IR (CH2Cl2, cmꢀ1) mCO 1959s. Calc. for

1388
M. El-khateeb / Polyhedron 25 (2006) 1386–1390
Table 1
fractometer with graphite monochromated Mo Ka radia-
tion at 173 K. The crystallographic data are shown in
Table 1. The cell parameters were determined from 5095
reflections collected in the range 1.96 6 h 6 30.04ꢁ. There
were 4473 independent reflections with 3717 observed
reflections (>2r(I)). The structure was solved by direct
method using SHELXS-97 [32] and DIFMAP synthesis using
SHELXTL-96 [33].
Selected crystal data and refinement parameters for CpFe(CO)2SeC(S)O-
4-C6H4Cl (1b)
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
C14H9ClFeO3SSe
427.53
0.13 · 0.10 · 0.08
monoclinic
P21/c
Unit cell dimensions
˚
a (A)
6.9410(10)
˚
b (A)
13.4830(10)
16.5320(10)
˚
3. Results and discussion
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90.00
98.27(5)
90.00
1531.1(3)
3.1. Synthesis and characterization of 1
3
˚
V (A )
The selenothiocarbonate complexes CpFe(CO)2SeC
(S)OR [R = Ph (1a), 4-C6H4Cl (1b), 4-C6H4F (1c), C6F5
(1d), 4-C6H4Me (1e)] were readily synthesized by stirring
a diethylether solution of chlorothionoformates and (l-
Se)[CpFe(CO)2]2 (Scheme 1) at room temperature.
Z
4
Index ranges
Dcalc (Mg mꢀ3
Radiation type
l (mmꢀ1
ꢀ9 < h < 9, 0 < k < 18, 0 < l < 23
)
1.855
Mo Ka
3.677
0.71069
1.96–30.04
0.0621
0.036
)
˚
k (A)
To the best of my knowledge, complexes 1 are the first
selenothiocarbonate of iron to be reported. The analogues
ethyl-dithiocarbonate complexes, Cp0Fe(CO)2SC(S)OEt
(Cp0 = C5H5, C5Me5) are reported by the reaction of
[Cp0Fe(CO)2]2 and [EtOC(S)S]2. Substitution reactions of
these dicarbonyl complexes with phosphine or phosphite
ligands gave Cp0Fe(CO)(L)SC(S)OEt (L = PPh3, PBu3,
P(OEt)3, P(OPh)3) [34,35]. Complexes 1 are air stable as
solids and in solutions. They are soluble in most common
organic solvents such as THF, CH2Cl2 but sparingly solu-
ble in hydrocarbons. These complexes were isolated as red-
brown solids and characterized by elemental analysis, IR
h Range (ꢁ)
R[F2>2r(F2)]
wR(F2)a
a
2
w ¼ 1=½r2ðF o2Þ þ ð0:0426PÞ ꢁ; where P ¼ ðF o2 þ 2F 2oÞ=3.
C13H5F5FeO2SSe: C, 34.32; H, 1.11; S, 7.05. Found: C,
33.71; H, 1.00; S 6.77%.
2.2.5. [CpFe(CO)(j2Se,S-SeC(S)O-4-C6H4Me)] (2e)
Yield: 92%. m.p. 88–89 ꢁC. 1H NMR (CDCl3) d 2.36 (s,
3H, CH3); 4.66 (s, 5H, C5H5); 7.02 (d, 2H, C6H4); 7.20 (d,
2H, C6H4). IR (CH2Cl2, cmꢀ1) mCO 1950s. Calc. for
C14H12FeO2SSe: C, 44.35; H, 3.19; S, 8.46. Found: C,
44.85; H, 3.07; S, 8.46%.
1
and H NMR spectroscopy. The solution IR spectra of 1
(in CH2Cl2) exhibited two strong absorbances in the car-
bonyl region at 2035–2041 and 1985–1997 cmꢀ1. These
mCO stretches are comparable to those of CpFe(CO)2-
SeSO2R (2038–2043 and 1993–1999 cmꢀ1) [29] and of CpFe-
(CO)2SeCO2R (2036–2043 and 1988–1993 cmꢀ1) [31] but
higher than those of selenocarboxylates, CpFe(CO)2SeCOR
2.3. X-ray structure analysis
Single crystal of 1b was obtained from CH2Cl2/hexane
mixture. Intensity data were collected on a KappaCCD dif-
CO
Fe
S
S
CO
Fe
Fe
Se
R
+
Fe
+
Cl
R
OC
OC
Se
O
OC
Cl
O
CO
CO
CO
1
hν
Fe
S
+
CO
OC
Se
OR
2
R= Ph (a), 4-C6H4Cl (b), 4-C6H4F (c), C6F5 (d), 4-C6H4Me (e)
Scheme 1.

M. El-khateeb / Polyhedron 25 (2006) 1386–1390
1389
(2030–2035 and 1965–1973 cmꢀ1) [23]. These results show
that the ligands: selenosulfonates, selenocarbonates and
selenothiocarbonates are of comparable basicity, and they
all have higher basicity than the selenocarbxylate ligands.
The 1H NMR spectra for complexes 1 are in accordance
with their formulation. Their spectra display a singlet in the
range 4.95–5.08 ppm for their cyclopentadienyl ring pro-
tons. This peak falls within the same range observed for
selenocarbonates CpFe(CO)2SeCO2R (4.98–5.09 ppm)
[12]. However, this peak is lower than that observed for
selenosulfonate, CpFe(CO)2SeSO2R (5.19–5.24 ppm) [29]
and of selenocarboxylate complexes, CpFe(CO)2SeCOR
(5.08–5.11 ppm) [23]. The resonances for the protons of
the R-groups are observed in the expected values and
multiplicity.
within the same range observed for CpFe(CO)(EPh3)-
SeCOR (4.61–4.77 ppm).
3.3. Crystal structure
The structure of CpFe(CO)2SeC(S)O-4-C6H4Cl (1b) was
determined crystallographically and is shown in Fig. 1. The
relevant bond parameters are listed in Table 2. The com-
plex adopts the geometry of a three-legged pianostool, with
Cp as the base and the two carbonyls and the Se-coordi-
nated selenothiocarbonate ligand as the legs. The Cp ligand
is bound to the metal in an g5-fashion with Fe–C bond dis-
˚
tances ranging between 2.081(3) and 2.112(3) A. The Fe–C
bond distances (of carbonyl ligands) of 1.785(3) and
˚
1.769(3) A are in normal range for CpFe(CO)2X com-
˚
plexes. The Fe–Se bond length of 2.3958(5) A is close to
3.2. Synthesis and characterization of 2
the range of Fe–Se bond lengths found in related iron com-
plexes such as CpFe(CO)2SeSO2C6H5 [29] and CpFe(CO)2-
SeCO2C2H5 [30]. The C@S bond distance of 1.633(3) A is
similar to that observed for (PPh3)2Pt(CS3) and
(dppe)PtCS3 [36].
˚
Photolytic reaction of a THF solution of complexes 1 in
the absence of added ligand leads to the generation of the
chelate complexes CpFe(CO)(j2Se,S-SeC(S)OR) (2). The
selenocarbonate ligands in 2 are bonded to the metal
through both the sulfur and the selenium atoms. These
dark red complexes are soluble in most organic solvents
including hydrocarbons. Solutions of 2 are quite air sensi-
tive even under inert atmosphere. Upon exposure to air,
they decompose within few minutes.
Table 2
˚
Selected bond length (A) and angles (ꢁ) of CpFe(CO)2SeC(S)O-4-C6H4Cl
(1b)
Fe–Se
Fe–C1
Fe–C2
Fe–C3
Fe–C4
Fe–C5
Fe–C6
Fe–C7
Se–C8
S1–C8
C1–O1
C2–O2
C8–O3
2.3985(2)
1.785(3)
1.769(3)
2.081(3)
2.098(3)
2.112(3)
2.100(3)
2.083(3)
1.881(2)
1.633(3)
1.131(3)
1.145(3)
1.351(3)
C8–Se–Fe
C1–Fe–Se
C2–Fe–Se
C2–Fe–C1
C8–O3–C9
O3–C8–S
O3–C8–Se
S1–C8–Se
107.80(7)
88.51(9)
90.10(9)
95.12(13)
119.71(19)
124.98(19)
112.99(17)
122.03(14)
1
Complexes 2 are characterised by IR, H NMR spec-
troscopy as well as elemental analysis. The IR spectra of
2 show the characteristic mCO absorption in the range
1947–1959 cmꢀ1. This absorption is similar to those of
CpFe(CO)(EPh3)SeCOR (1941–1957 cmꢀ1) and are lower
than those of the starting complexes 1. These differences
might be attributed to the weak p-acid character of the
chelate selenothiocarbonate ligand compared to that of
1
carbonyl ligand. The H NMR spectra of 2 show the Cp-
peak in the range 4.65–4.69 ppm. This peak is lower than
that of the corresponding Cp-peak of complexes 1 and
Fig. 1. ORTEP drawing of CpFe(CO)2SeC(S)O-4-C6H4Cl (1b).

1390
M. El-khateeb / Polyhedron 25 (2006) 1386–1390
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4. Supplementary materials
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Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC No. 277847 for compound 1b. Copies 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).
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The author thanks the Deanship of Research, Jordan
University of Science and Technology for financial sup-
port, Grant No. 119/2003. He also thanks Prof. Richard
Welter (University of Strasburg, France) for determining
the X-ray structure.
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