Synthesis and spectroscopic characterisation of compounds with formula [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] (n=3, 4 and 6)

Article abstract of DOI:10.1016/S0022-328X(01)01277-3

This work describes the synthesis and characterisation of the title compounds. This is the second in a series of reactions involving iron bis-phosphine cluster compounds [{Fe₃(CO)₁₁}Ph₂P(CH₂)_nPPh₂{Fe(CO)₄}] and [{Fe₃(CO)₁₁}₂Ph₂P(CH₂)_nPPh₂] (n=3, 4 and 6). Here, the iron bis-phosphine cluster compounds are reacted with stoichiometric amounts of diphenyldisulphide (Ph₂S₂) in toluene at 65-70 °C for 30 min. The reactions afforded three products regardless of the n-value. Irrespective of the iron-containing reagent, one product is common to all reactions. A total of seven different compounds were isolated, six of which are new. The product formulations are: 1. the known compound [Fe₂(SPh)₂(CO)₆] (common product); 2. [{Fe₂(SPh)₂(CO)₅}Ph₂P(CH₂)_nPPh₂{Fe(CO)₄}]; and 3. [{Fe₂(SPh)₂(CO)₅}₂Ph₂P(CH₂)_nPPh₂], (n=3, 4 and 6). Yields ranged 2-37% depending on the particular reactions. Reactions involving the {Fe₃Fe} type species with [Ph₂S₂] (1:1 or 1:2 mole ratio) afforded predominantly phosphine sulphur compounds type (ii) above, whereas, when the {Fe₃Fe₃} type species were reacted (1:2 or 1:4 mole ratio), the major products were of type (iii) above.

Full text of DOI:10.1016/S0022-328X(01)01277-3

Journal of Organometallic Chemistry 642 (2002) 40–47
www.elsevier.com/locate/jorganchem
Synthesis and spectroscopic characterisation of compounds with
formula [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] and
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] (n=3, 4 and 6)
Rosamund Hourihane a,*, Geraldine Gray a, Trevor Spalding b, Tony Deeney c
a Chemistry Department, Cork Institute of Technology, Rossa A6enue, Bishopstown, Cork, Ireland
b Chemistry Department, Uni6ersity College Cork, College Road, Cork, Ireland
c Physics Department, Uni6ersity College Cork, College Road, Cork, Ireland
Received 18 April 2001; received in revised form 19 September 2001
Abstract
This work describes the synthesis and characterisation of the title compounds. This is the second in a series of reactions
involving iron bis-phosphine cluster compounds [{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe3(CO)11}2Ph2P(CH2)nPPh2]
(n=3, 4 and 6). Here, the iron bis-phosphine cluster compounds are reacted with stoichiometric amounts of diphenyldisulphide
(Ph2S2) in toluene at 65–70 °C for 30 min. The reactions afforded three products regardless of the n-value. Irrespective of the
iron-containing reagent, one product is common to all reactions. A total of seven different compounds were isolated, six of which
are new. The product formulations are:
(i) the known compound [Fe2(SPh)2(CO)6] (common product);
(ii) [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}]; and
(iii) [{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2], (n=3, 4 and 6).
Yields ranged 2–37% depending on the particular reactions. Reactions involving the {Fe3ꢀFe} type species with [Ph2S2] (1:1 or
1:2 mole ratio) afforded predominantly phosphine sulphur compounds type (ii) above, whereas, when the {Fe3ꢀFe3} type species
were reacted (1:2 or 1:4 mole ratio), the major products were of type (iii) above. © 2002 Elsevier Science B.V. All rights reserved.
Keywords: Iron; Diphosphine; Disulphide; Bridging ligand; Mo¨ssbauer
1. Introduction
and [{Fe2S2(CO)5}2Ph2P(CH2)nPPh2] (n=3, 4 and 6).
In these reactions, the Fe3-unit is ‘degraded’, but at the
same time the cluster is expanded from three atoms
{Fe3} to four {Fe2S2}.
We report here the second in a series of reactions
involving iron bis-phosphine cluster compounds
[{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe3-
(CO)11}2Ph2P(CH2)nPPh2] (n=3, 4 and 6) with sulphur
and selenium ligands. In the first of the series, these
iron bis-phosphine cluster compounds were reacted
with cyclohexene episulphide [SC6H10] [1]. Reactions
afford clusters with fewer iron atoms but with S-atoms
incorporated. Compounds with two di iron di sulphur
units linked by a bis-phosphine ligand were reported,
formulation [{Fe2S2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}]
The series of reactions described in this work add
thiolate sulphur, diphenyl disulphide (Ph2S2). Com-
pounds with general formula [{Fe2(SPh)2(CO)5}-
Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe2(SPh)2(CO)5}2-
Ph2P(CH2)nPPh2] (n=6, bis(diphenylphosphino)hexane
(dpph); n=4, bis(diphenylphosphino)butane (dppb);
and n=3, bis(diphenylphosphino)propane (dppp)) are
the new products formed in the reaction between
{Fe3ꢀFe} and {Fe3ꢀFe3} bis-phosphine double clusters
with diphenyldisulphide (Ph2S2). [Fe2(SPh)2(CO)6] is a
common product formed in all reactions. Products
reported here maintain the bis-phosphine link, reduce
the iron content of the cluster and add thiolate. This is
* Corresponding author. Fax: +353-21-545343.
E-mail address: rhourihane@cit.ie (R. Hourihane).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01277-3

R. Hourihane et al. / Journal of Organometallic Chemistry 642 (2002) 40–47
41
resulting when the former ligand is reacted, are unex-
pected.
similar to what was observed and reported by us previ-
ously in the first series, when sulphur was added. The
compounds presented here were characterised by IR
and Mo¨ssbauer spectroscopies as well as C, H, S and
Fe analyses (Table 3).
2. Experimental
Simple phosphine compounds of the type
[Fe2(SPh)2(CO)6−n(PR3)n] (R=Me, Ph, OMe) [2–8],
and ditertiary phosphine compounds where the
bis-phosphine ligand used was dppm and dppe,
have been reported previously [3,4,7,8]. De Beer and
Haines found that the bis-phosphine ligand attached
either
1. monodentate at one iron atom as in [Fe(SR)2-
(CO)3Fe(CO)2L] (R=Me, Et; L=Ph2PCH2PPh2,
dppm, Ph2P(CH2)2PPh2, dppe; benzene, room tem-
perature);
2.1. Materials
All reactions were carried out under an inert atmo-
sphere. Subsequent work was carried out in air. All
purified products were stored in the refrigerator, or
under vacuum. Tetrahydrofuran (THF) was distilled
freshly from potassium diphenylketyl. Toluene was dis-
tilled freshly from sodium diphenylketyl. Hexane and
CH2Cl2 were dried over P2O5 and distilled prior to use.
All other solvents were of reagent grade and used as
received. Bisphosphine ligands and Ph2S2 were commer-
cial products obtained from Aldrich Chemicals, UK.
Iron cluster compounds [{Fe3(CO)11}Ph2P(CH2)n-
PPh2{Fe(CO)4}] and [{Fe3(CO)11}2Ph2P(CH2)nPPh2]
(n=3, 4 and 6) were prepared as described by us in the
literature [18,21].
2. symmetrically, bridging the two iron atoms of the
‘Fe2’ unit [Fe(SR)(CO)2]2L (L=(dppm), Ph2PNEt-
PPh2; toluene or xylene); or
3. when L=dppe, a trisubstituted product [Fe(CO)2-
(SR)2LFe(CO)L] was the product formed where one
bisphosphine ligand was bidentate and the other
was monodentate, to the ‘Fe2’ unit [3]. The latter
species described is also the product formed when
[Fe2(SR)2(CO)6] is irradiated with UV light in ben-
zene solution (R=Me, Et; L=dppm, dppe or cis-
Ph2PC2H2PPh2).
Cluster compounds where two ‘Fe2’ units are bridged
by two diphosphine ligands [Fe2(SR)2(CO)4L]2 (L=
dppe) have also been reported [9].
All of the aforementioned cluster compounds, how-
ever, resulted from the reaction of an Fe2(SR)2 system
with simple phosphines, yielding cluster compounds
which have undergone substitution without expansion,
i.e. the number of iron atoms in the cluster remains
constant.
2.2. Apparatus
Infrared spectra were recorded on Perkin–Elmer 682
or Mattson Polaris FTIR 10410 spectrophotometers.
Solution spectra were obtained in NaCl cells. Relative
intensities were designated as vs, very strong; s, strong;
m, medium; w, weak; vw, very weak; other descriptions
were sh, shoulder; shp, sharp; br, broad.
Mo¨ssbauer spectra of the iron-containing compounds
were recorded at liquid nitrogen temperatures (80 K)
using a commercial constant acceleration drive unit and
transducer (Marwell Instruments) in conjunction with a
Canberra System 40 multichannel analyser as previ-
ously described [19]. The source was 57Co in Rh and
was of 20-mCi nominal strength. Data were processed
on a Vax 11/780 computer and all data were referred to
the spectrum of sodium nitroprusside as standard.
When sufficient quantities of material were available,
samples were prepared for Mo¨ssbauer experiments by
wrapping 0.05–0.1 g of the compound in paper, which
was then wrapped in adhesive tape, forming a pouch
and placed in the g-ray beam. For small samples (less
than 0.03 g), the material was dissolved in the least
amount of CH2Cl2 needed to transfer the compound to
the prepared pouch. The solvent was allowed to evapo-
rate before the sample was frozen in liquid nitrogen.
Recording times varied between 24 h and 4 days.
All C and H analyses were carried out on a PE 240
analyser. Sulphur content was determined by the oxy-
gen flask method. Iron content was determined by
atomic absorption spectroscopy using a Pye Unicam SP
191 atomic absorption spectrophotometer.
The literature also shows that when ‘Fe3’ clusters are
reacted with thiolate the products are thiolate substi-
tuted di iron carbonyl clusters [10–14]. However, when
an ‘Fe3’ system is reacted with S and then P, the Fe3
cluster is not degraded [15–17].
The compounds described in this work illustrate that
when an Fe3 bisphosphine-substituted unit is further
reacted with a thiolate ligand simultaneous reduction of
the Fe3 cluster to an Fe2 cluster and expansion from a
three-atom cluster to a four-atom bisphosphine-substi-
tuted unit incorporating thiolate occurs. Thus, reactions
involving iron bis-phosphine cluster compounds
[{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe3-
(CO)11}2Ph2P(CH2)nPPh2] (n=3, 4 and 6) with sulphur
(cyclohexene episulphide) or thiolate sulphur (Ph2S2)
give similar type of compounds. These products might
be expected for the latter type of ligand, since they
conform to literature reports, however, the products,

42
R. Hourihane et al. / Journal of Organometallic Chemistry 642 (2002) 40–47
2.3. Standard reaction procedure for the reaction between
either of the following iron-containing compounds
[{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4}], and
[{Fe3(CO)11}2Ph2P(CH2)nPPh2], n=3–6 and
diphenyldisulphide
from 2 days to 2 weeks. The products in the form of
microcrystalline solids were recovered and characterised
by IR and Mo¨ssbauer spectroscopies as well as chemi-
cal analysis (Table 3), as
[Fe2(SPh)2(CO)6] (1);
[{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] (n=
Each of the title compounds were reacted with a
stoichiometric amount of Ph2S2 in toluene under an
inert atmosphere at 65–70 °C for 30 min. Specific
reaction details are outlined in Tables 1 and 2. The
extent of the reaction was monitored by TLC using
silica gel 60 as the stationary phase and CH2Cl2–hex-
ane as eluant. The reaction mixture was filtered and the
toluene removed under reduced pressure yielding a
orange-red residue. The residue was dissolved in
CH2Cl2 and chromatographed using preparative TLC,
with silica gel (PF254) on glass plates and a mixture of
CH2Cl2–hexane (3:2) as eluant.
3, (2); n=4, (3); n=6, (4);
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2 (n=3, (5); n=
4, (6); n=6, (7).
3. Results and discussion
3.1. The reaction between
[{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4} or
[{Fe3(CO)11}2Ph2P(CH2)nPPh2] (n=3, 4, 6) and
diphenyldisulphide [(C6H5)2S2]
Chromatographic separation afforded four products
one of which had a red–orange colour and three were
orange in colour. Only three products were produced in
sufficient quantities to be isolated. These were extracted
into CH2Cl2. The solvent was removed under reduced
pressure and the residue was redissolved in hexane. The
volume of hexane was reduced to 5 ml in each case and
the solutions were stored at −20 °C for times ranging
3.1.1. Syntheses
The title reactions were carried out in toluene at
65–70 °C for 30 min. Three products were isolated for
each reaction (Scheme 1). One product 1 was common
to all reactions. Thus in total, seven different com-
pounds, six of which are new, were isolated and charac-
terised. The products were separated by preparative
TLC. These were characterised by IR and Mo¨ssbauer
Table 1
Reaction of [{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4}] (A) with diphenyldisulphide (B)
n
Reagent A (g (mmol))
0.095 (0.086)
Reagent B (g (mmol))
0.038 (0.172)
Product formula
g (% Yield)
6
[Fe2(SPh)2(CO)6]
0.23 (53.7)
0.024 (25.4)
0.009 (7.2)
0.015 (25.2)
0.05 (38.9)
0.014 (8.5)
0.02 (50.9)
0.015 (18.2)
0.003 (2.1)
[{Fe2(SPh)2(CO)5}Ph2P(CH2)6PPh2{Fe(CO)4}]
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)6PPh2]
[Fe2(SPh)2(CO)6]
[{Fe2(SPh)2(CO)5}Ph2P(CH2)4PPh2{Fe(CO)4}]
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)4PPh2]
[Fe2(SPh)2(CO)6]
4
3
0.128 (0.119)
0.086 (0.079)
0.026 (0.119)
0.017 (0.079)
[{Fe2(SPh)2(CO)5}Ph2P(CH2)3PPh2{Fe(CO)4}]
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)3PPh2]
Mole ratio A:B, 1:1; reaction temperature, 65–70 °C; reaction solvent toluene, 30 ml; reaction time, 30 min. Yields calculated as in Ref. [1].
Table 2
Reaction of [{Fe3(CO)11}2Ph2P(CH2)nPPh2] (A) with diphenyldisulphide (B)
n
Reagent A (g (mmol))
0.082 (0.058)
Reagent B (g (mmol))
0.025 (0.116)
Product formula
g (% yield)
6
[Fe2(SPh)2(CO)6]
0.018 (63.8)
0.002 (3.3)
0.005 (5.6)
0.016 (44.5)
0.013 (18.2)
0.036 (36.6)
0.029 (52.1)
0.017 (14.1)
0.020 (13.5)
[{Fe2(SPh)2(CO)5}Ph2P(CH2)6PPh2{Fe(CO)4}]
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)6PPh2]
[Fe2(SPh)2(CO)6]
[{Fe2(SPh)2(CO)5}Ph2P(CH2)4PPh2{Fe(CO)4}]
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)4PPh2]
[Fe2(SPh)2(CO)6]
4
3
0.097 (0.071)
0.153 (0.118)
0.02 (0.091)
0.024 (0.118)
[{Fe2(SPh)2(CO)5}Ph2P(CH2)3PPh2{Fe(CO)4}]
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)3PPh2]
Mole ratio A:B, 1:2 or 1:2; reaction temperature, 65–70 °C; reaction solvent toluene, 30 ml; reaction time, 30 min. Yields calculated as in Ref.
[1].

Table 3
Characteristics of substituted iron carbonyl compounds with proposed [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] formulations
Compound
Anal. Calc. (Found)
IR
Mo¨ssbauer
Site
C
H
S
Fe
wmax CO (cm−1
)

l
Z
Y
[Fe2(SPh)2(CO)6] (1) a,b
[Fe2(SPh)2(CO)6] (1) c
2070, 2036,
2003, 1995
2065 m, shp,
2028 vs,shp,
2000 w, shp,
1985 vs, br
2041 s,
Fe(CO)3SPh
Fe(CO)3SPh
0.32 1.01
43.41
(43.58)
2.03
(2.16)
12.89
(13.15)
22.40
(21.25)
0.35 1.01 0.25
[{Fe2(SMe)2(CO)5}PEt3] d
/
1981 s,
1967 s,
1923 m
[{Fe(CO4)2}Ph2P(CH2)3PPh2] e
2040 vs, shp,
2010 vw,
1955 vw,
1960 s,
1920 vs br
2040 vs, shp,
1992 vw, sh
1955, s,
e
[{Fe(CO)4}Ph2P(CH2)2]2
1929 vs, br
2036 s,
1980 s,
[{Fe2(SEt)2(CO)5}Ph2P(CH2)2PPh2] d
[{Fe2(SEt)2(CO)5}Ph2PCH2PPh2] d
642
1922 m
)
Fe(CO)3(SEt)2
Fe(CO)3(SEt)2P
Fe(CO)3(SMe)2P
Fe(CO)4tP
0.29 1.24 0.23
0.31 0.76 0.25
0.31 0.84 0.30
d
[{Fe(SMe)(CO)2}Ph2PCH2PPh2]2
0
[{Fe2(SPh)2(CO)5}Ph2P(CH2)6PPh2{Fe(CO)4}] (4) c 56.07
3.88
(3.80)
5.88
(5.55)
15.33
(15.45)
2038 s, shp,
1990 sh,
1.6 0.19 2.42 0.22
2.5 0.39 1.23 0.40
4
(55.95)
Fe(CO)3(SPh)2
1986 sh,
1970 s, br,
1955 sh,
1920 s, br,
1915 s, br

Table 3 (Continued)
Compound
Anal. Calc. (Found)
IR
Mo¨ssbauer
C
H
S
Fe
15.73
wmax CO (cm−1
)
Site

l
Z
Y
[{Fe2(SPh)2(CO)5}Ph2P(CH2)4PPh2{Fe(CO)4}] (3) c 55.29
3.60
(3.91)
6.03
2040 s, shp,
1970 s, br,
1960 sh,
Fe(CO)4 tP
Fe(CO)3(SPh)2
Fe(CO)2(SPh)2P 3.4
1.6 0.20 2.40 0.23
2.5 0.37 1.25 0.40
(55.63)
(6.11)
(15.07)
0.90
1950 sh,
1920 s, br
2038 vs, shp,
1969 vs, br,
1915 vs, br
2038 vs, shp,
1970 vs, br,
1950 sh,
[{Fe2(SPh)2(CO)5}Ph2P(CH2)3PPh2{Fe(CO)4}] (2) c 54.89
3.45
(3.91)
6.11
(5.47)
15.94
(16.19)
Fe(CO)4 tP
Fe(CO)3(SPh)2
Fe(CO)2(SPh)2P 3.4
Fe(CO)3(SPh)2
Fe(CO)2(SPh)2P
1.6 0.20 2.41 0.25
2.5 0.38 1.23 0.40
(54.46)
/
0.85
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)6PPh2] (7) c
55.12
3.75
(4.08)
9.21
(9.50)
16.00
(16.05)
0.39 1.01 0.40
(55.00)
1919 w, br
1910 w, br
2040 s, shp,
1970 vs, br,
1955 sh,
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)4PPh2] (6) c
54.49
(54.62)
3.60
(4.28)
9.39
(9.44)
16.33
(16.65)
Fe(CO)3(SPh)2
Fe(CO)2(SPh)2P 2.3
1.4 0.36 1.20 0.65
0.88
1960 sh,
1950 sh,
1915 m, br
2040 vs, shp,
1970 vs, br,
1955 sh,
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)3PPh2] (5) c
54.17 (54.34)
3.46 (4.08)
9.47 (9.66)
16.52 (16.78)
Fe(CO)3(SPh)2
Fe(CO)2(SPh)2P 2.3
1.4 0.37 1.20 0.65
0.88
642
(
1915 w, br
4
, line assignment; l, isomer shift; Z, quadrupole splitting; Y, peakwidth at half height. All isomer shift data are referenced to sodium nitroprusside, to reference to iron subtract 0.257 from values
in the table.
4
a IR solvent CS2.
b Refs. [20,22].
c IR Solvent CH2Cl2 (Ref.: this work).
d Ref. [3].
e Refs. [1,21].

R. Hourihane et al. / Journal of Organometallic Chemistry 642 (2002) 40–47
45
higher yields. An exception to this is when n=3, here
both product formulations have similar % yields.
3.1.2. Spectroscopic characterisation
3.1.2.1. Infrared spectra. A summary of the energies of
the band maxima of the IR absorptions in the carbonyl
region for compounds 1–7 is given in Table 3 along
with data previously reported for 1 [20].
Considering compounds of the type [{Fe2(SPh)2-
(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] n=3, (2); n=4, (3);
n=6, (4), it can be seen that all three have very similar
CO absorption patterns. For the proposed formulation,
a combination of absorptions due to two distinct units,
i.e. Fe(CO)4 and Fe2(SPh)2(CO)5 would be expected.
Characteristic absorptions for the Fe(CO)4 unit occur
at 2040 vs, 1990 sh, 1955 s, and 1920 vs cm−1 in
CH2Cl2, for example, compounds [{Fe(CO)4}Ph2P-
(CH2)3]2) and [{Fe(CO)4}Ph2P(CH2)2]2), [21] (Table 3).
While those of the Fe2(SR)2(CO)5 unit occur at 2036 s,
1980 s, and 1922 m cm−1 in CH2Cl2, for example,
compound [Fe2(SEt)2(CO)5Ph2P(CH2)2PPh2] [3] (Table
3). Since these absorptions overlap largely, it would be
difficult to distinguish these units by IR spectroscopy
alone. To take a specific example, the spectrum of
compound 4, n=6, has absorptions at 2038 s, shp,
1990 sh, 1970 s, br, 1960 sh, 1955 sh, 1920 s, br and
1915 s, br cm−1 in CH2Cl2, and clearly, they cannot
unambiguously be assigned to specific units.
The possibility of chelating phosphine ligands or
bidentate ligands being attached to one iron atom in
the ‘Fe2’ species can apparently be ignored, since the
absorptions due to these types of compounds are
clearly different from those reported in this work. For
example, [Fe(SMe)2(CO)3Fe(CO) (dppe)] has CO ab-
sorptions at 2017, 1946, and 1900 cm−1, where the
phosphine is chelating to the iron [3] and
[{Fe(SEt)2(CO)2}2 (dppm)] has CO absorptions at 1900,
1946 and 1927 cm−1, where the phosphine is bidentate
to the iron [3].
If the IR spectra of compounds of the type
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] n=3, (5); n=4,
(6); n=6, (7) are examined, it can be seen that all three
compounds have very similar CO absorptions. Their
spectra can be analysed more successfully than those
for 2–4 since there is only the Fe2(SPh)2(CO)5 unit to
consider and a number of similar compounds are re-
ported in the literature [1,3]. For example, compound 7
shows carbonyl absorptions at 2038 vs, shp, 1970 vs,
br, 1950 sh, 1919 w, br, 1910 w, br cm−1 in CH2Cl2.
The compound [{Fe2(SEt)2(CO)5}Ph2P(CH2)nPPh2]
with carbonyl absorptions at 2036 s, 1980 s, and 1922
m in CH2Cl2 or [Fe2(SMe)2(CO)5PEt3] with CO absorp-
tions at 2041 s, 1981 s, 1967 s, 1923 m in hexane [3]
compare well with those obtained for compound 7.
Scheme 1. Proposed reaction scheme for the formation of compounds
with formulae: (a) Fe2(SPh)2(CO)6 (1); {[Fe2(SPh)2(CO)5}Ph2P-
(CH2)6PPh2{Fe(CO)4]} (4); {[Fe2(SPh)2(CO)5]Ph2P(CH2)6PPh2[Fe2-
(SPh)2(CO)5]} (7).
spectroscopies and C, H, S and Fe analyses (Table 3).
The product formulations are:
(i) the single common product [Fe2(SPh)2(CO)6] (1);
(ii) [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}]
n=3, (2); n=4, (3); n=6, (4);
(iii) [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2] n=3, (5);
n=4, (6); n=6, (7).
Tables 1 and 2 illustrate how the choice of starting
material influences product yield. For example, reac-
tions
involving
[{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe-
(CO)4}] afforded the phosphine-containing compounds,
which were predominantly of the type [{Fe2(SPh)2-
(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] n=3, (2); n=4, (3);
n=6, (4).
However, when the compounds [{Fe3(CO)11}2Ph2P-
(CH2)nPPh2] were the starting materials the products
with [{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] (n=3, (5);
n=4, (6); n=6, (7)) formulation were produced in

46
R. Hourihane et al. / Journal of Organometallic Chemistry 642 (2002) 40–47
Similar assignments can be made for compounds 5 and
6.
s−1 for compound 1 is the same as that reported in the
literature, but the isomer shift value of 0.35 mm s−1 is
shifted slightly from the value of 0.32 mm s−1 reported
previously [20,22]. However, since all values are90.02
mm s−1, both values overlap within allowed experi-
mental error.
3.1.2.2. Mo¨ssbauer spectra. The values (mm s−1) of
isomer shift (l), quadrupole splitting (Z) together with
the line assignment, numbered 1–6 from left to right,
for compounds 1–7 are given in Table 3. The Mo¨ss-
bauer spectra for compounds 2, 6 and 7 are illustrated
in Fig. 1. The quadrupole splitting value of 1.01 mm
The Mo¨ssbauer spectra of compounds [{Fe2(SPh)2-
(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] (2–4) all show three
resolved doublets, which distinguish the three different
iron sites within these compounds. Fig. 1 contains the
spectrum of 2. The site with the largest Z-value (ca.
2.41 mm s−1) is assigned to the Fe(CO)4 unit with a
monodentate phosphine ligand attached in an apical
position. This assignment is justified by comparison
with literature values [1]. The second largest quadru-
pole splitting value ca. 1.24 mm s−1 is assigned to the
unsubstituted iron site of the Fe2(SPh)2(CO)5 unit, since
it is most like that of the ‘parent molecule’
[Fe2(SPh)2(CO)6] (1) (1.01 mm s−1). Lastly, the quadru-
pole splitting of ca. 0.87 mm s−1 is assigned to the
substituted iron atom of the ‘Fe2’ unit, i.e. the Fe-
(SPh)2(CO)2P site. These assignments are justified by
comparison with literature data [3,20,22,23]. For exam-
ple, the compounds [{Fe2(SR)2(CO)5}Ph2P(CH2)PPh2]
{R=Et, R=Me} have Z=1.24 and 1.13 mm s−1
,
respectively, for the unsubstituted site, and Z=0.76
and 0.74 mms−1, respectively, for the substituted site
[3]. Further support for the correctness of the assign-
ment for the substituted site comes from comparison of
the quadrupole splitting value with that for the iron
atoms in [Fe(SMe)(CO)2 dppm]2 Z=0.84 mm s−1
,
where both irons are substituted by phosphine ligands
in a monodentate fashion [3]. The possibility of chelat-
ing phosphine ligands may be ruled out by comparison
with the Z-value for the phosphine substituted site
in [Fe(SPh)2(CO)3Fe(CO) dppe], which
has a Z of 0.61 mm s−1, clearly different to the lowest
Z-value of ca. 0.87 mm s−1 in compounds 2–4.
Support for the unsubstituted site assignment comes
from examination of the isomer shift values. There is
very little difference between that of the parent
molecule [Fe2(SPh)2(CO)6] (1) with l=0.35, and values
for compounds 2–4 with l=0.38, 0.37, and 0.39 mm
s
−1, respectively. This suggests that the site is essen-
tially unchanged.
The three compounds [{Fe2(SPh)2(CO)5}2Ph2P-
(CH2)nPPh2] (5–7) contain two iron sites in the
Fe2(SPh)2(CO)5 units. Each has one Fe(SPh)2(CO)2Pꢀ
and one Fe(SPh)2(CO)3ꢀ. The two iron sites are distin-
guished clearly in compounds 5 and 6, and have similar
Mo¨ssbauer parameters to those for the Fe2(SPh)2(CO)5
unit in compounds 2–4 above, discussed previously.
However, in the spectra of compound 7 these sites are
unresolved and are assigned values of l=0.39 and
Z=1.01 mm s−1 for both sites.
Fig. 1. Mo¨ssbauer spectra of compounds with formulae (a)
[{Fe2(SPh)2(CO)5}Ph2P(CH2)3PPh2{Fe(CO)4}]
(2);
[{Fe2(SPh)2-
(CO)5}2Ph2P(CH2)nPPh2 (b) n=4, (6); (c) n=6, (7).

R. Hourihane et al. / Journal of Organometallic Chemistry 642 (2002) 40–47
47
(b) G. Zotti, R.D. Rieke, J.S. McKennis, J. Organomet. Chem.
228 (1982) 281.
[6] P.M. Treichel, R.A. Crane, R. Mathews, K.R. Bonnin, D.
Powell, J. Organomet. Chem. 402 (1991) 233.
[7] M.S. Arabi, R. Mathieu, R. Pailblanc, J. Organomet. Chem. 177
(1979) 199.
[8] G. Le Borgne, D. Grandjean, R. Mathieu, R. Pailblanc, J.
Organomet. Chem. 131 (1977) 429.
[9] J.A. DeBeer, R.J. Haines, J. Organomet. Chem. 36 (1972) 297.
[10] J.A. DeBeer, R.J. Haines, J. Chem. Soc. Chem. Commun. (1970)
288.
Thus the arrangement of ligands proposed for com-
pounds of the type [{Fe2(SPh)2(CO)5}Ph2P(CH2)n-
PPh2{Fe(CO)4}] (2–4) consists of an Fe(CO)4 unit with
the phosphine ligand attached in an apical position and
an Fe2(SPh)2(CO)5 unit with the phosphine ligand at-
tached either to an apical or basal position, ((b) Scheme
1). The proposed structure for compounds of type
[{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] (5–7) consists of
two Fe2(SPh)2(CO)5 units linked by the diphosphine
ligand via combinations of apical or basal positions
(Scheme 1(c)).
[11] R.B. King, J. Am. Chem. Soc. 84 (1962) 2460.
[12] L.F. Dahl, C. Martell, D.L. Wampler, J. Am. Chem. Soc. 83
(1961) 1761.
[13] (a) W. Heiber, Z. Anorg. Allg. Chem. 233 (1937) 353;
(b) W. Heiber, Z. Anorg. Allg. Chem. 305 (1964) 265.
[14] J.A. Adelcke, Y.W. Chen, L.K. Lui, Organometals 11 (1992)
2543.
[15] P. Mathur, I.J. Mavunkal, V. Rugmini, J. Organomet. Chem.
367 (1989) 243.
Acknowledgements
We wish to thank Cork Institute of Technology for
scholarship support for a student.
[16] S. Jy Wang, R.J. Angelici, Inorg. Chem. 27 (1988) 3233.
[17] A. Darchen, C. Mahe´, H. Patin, J. Chem. Soc. Chem. Commun.
(1982) 243.
[18] G. Ferguson, R. Houihane, T.R. Spalding, Acta Crystallogr.,
Sect. C C47 (1991) 544.
[19] W.E. Carroll, F.A. Deeney, F.J. Lalor, J. Organomet. Chem. 198
(1980) 189.
[20] E. Kostiner, M.L.N. Reddy, D.S. Urch, A.G. Massey, J.
Organomet. Chem. 15 (1968) 383.
References
[1] R. Hourihane, G. Gray, T.R. Spalding, T. Deeney, J.
Organomet. Chem. 595 (2000) 191.
[2] G. Natile, L. Maresca, G. Bor, Inorg. Chim. Acta 23 (1977) 37.
[3] J.A. de Beer, R.J. Haines, R. Greatrex, N.N. Greenwood, J.
Chem. Soc. A (1971) 3271.
[21] R. Hourihane, Ph.D. Thesis, U.C.C., Ireland, 1992.
[22] E. Kostiner, A.G. Massey, J. Organomet. Chem. 19 (1969) 233.
[23] R.V. Parish, The Organic Chemistry of Iron, vol. 1, Academic
Press, New York, 1978.
[4] A. Darchen, H. Mousser, H. Patin, J. Chem. Soc. Chem. Com-
mun. (1988) 968.
[5] (a) R.E. Dessy, R. Kornmann, C. Smith, R. Haytor, J. Am.
Chem. Soc. 90 (1968) 2001;