Chemical reactivity of [(μ-RSe) (μ-S) {Fe2(CO)6}2(μ4-S)]-: Synthesis and characterization of (μ-RSe) (μ-R'S) {Fe2(CO)6}2(μ4-S) and (μ3-S)2</

Article abstract of DOI:10.1016/S0277-5387(00)00317-X

The reaction Of (μ-S₂)Fe₂(CO)₆ with [(μ-RSe) (μ-CO)Fe₂(CO)6]^- gives the anionic complexes [(μ-RSe) (μ-S){Fe₂(CO)₆}₂(μ₄-S)]^- (1). Reactions of 1 w

Full text of DOI:10.1016/S0277-5387(00)00317-X

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 713–718
Chemical reactivity of [(m-RSe)(m-S){Fe2(CO)6}2(m4-S)]y:
synthesis and characterization of (m-RSe)(m-R9S){Fe2(CO)6}2(m4-S)
and (m3-S)2Fe3(CO)8[Se(Ph)Fe(CO)2Cp]
b
b
Huai-Ben Zheng a, Shao-Bin Miao a, Zhong-Xia Wang a, , Zhong-Yuan Zhou , Xiang-Ge Zhou
*
a Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, People’s Republic of China
b Chengdu Institute of Organic Chemistry, Chinese Academy of Science, Chengdu 610041, People’s Republic of China
Received 27 October 1999; accepted 28 January 2000
Abstract
The reaction of (m-S2)Fe2(CO)6 with [(m-RSe)(m-CO)Fe2(CO)6]y gives the anionic complexes [(m-RSe)(m-S){Fe2(CO)6}2(m4-
S)]y (1). Reactions of 1 with electrophiles such as alkyl halides, acid chlorides and PhN2BF4 form neutral complexes (m-RSe)(m-
R9S)[Fe2(CO)6]2(m4-S) (RsPh, R9sMe 2a; RsPh, R9sPhCH2 2b; RsEt, R9sMe 2c; RsPh, R9sCH3C(O) 3a; RsPh, R9sPhC(O)
3b; RsEt, R9sPhC(O) 3c; RsR9sPh 4). Treatment of 1 with Cp(CO)2FeI affords pentanuclear iron complexes (m-RSe)[m-
Cp(CO)2FeS][Fe2(CO)6]2(m4-S) (RsPh 5a; RsEt 5b). From the reaction mixture of 1 (RsPh) and Cp(CO)2FeI, (m3-
S)2Fe3(CO)8[Se(Ph)Fe(CO)2Cp] (6) was also obtained. The structure of complex 6 was determined by single-crystal X-ray analysis.
q2000 Elsevier Science Ltd All rights reserved.
Keywords: Iron; Selenium; Sulfur; Synthesis; Reaction
1. Introduction
The chemical reactivities of [(m-RS)(m-CO)Fe2-
(CO)6]y and [(m-RSe)(m-CO)Fe2(CO)6]y have been
studied extensively [1–17]. However, most studies concen-
trated mainly on reactions with organic reagents. Studies of
the reactivities toward organometalliccompounds,especially
cluster complexes, are relatively rare. Available examples
(1)
include the reactions with organomercury [3–5], organogold
[15], organoiridium [16], organorhenium and organoman-
ganese [17] compounds. Recently we reported the reaction
2. Experimental
of [(m-RS)(m-CO)Fe2(CO)6]y with (m-S2)Fe2(CO)6,
All reactions were carried out under nitrogen using stan-
yielding anionic complexes [(m-RS)(m-S){Fe2(CO)6}2-
dardSchlenktechniques. Tetrahydrofuran(THF)anddiethyl
(m4-S)]y (see Eq. (1)) [18], which reacted readily with
ether were distilled from sodium benzophenone ketyl. PhSeH
electrophiles to form neutral complexes of the type (m-
[19], PhN2BF4 [20], Fe3(CO)12 [21], Cp(CO)2FeI [22]
RS)(m-R9S)[Fe2(CO)6]2(m4-S). To comparethereactivity
and (m-S2)Fe2(CO)6 [23] were prepared by published pro-
of [(m-RSe)(m-CO)Fe2(CO)6]y with that of [(m-RS)(m-
cedures. The solution of [(m-RSe)(m-CO)Fe2(CO)6]y
CO)Fe2(CO)6]y, we have investigated the reaction of [(m-
(RsPh, Et) was prepared by the method described in the
literature [8,14]. The progress of all reactions was monitored
by thin-layer chromatography. Infrared spectra (KBr disk)
RSe)(m-CO)Fe2(CO)6]y with (m-S2)Fe2(CO)6, and the
reactivity of the resulting complexes [(m-RSe)(m-S)-
{Fe2(CO)6}2(m4-S)]y toward electrophiles. Herein we
report the results.
1
were obtained using a VECTOR22 spectrometer. H NMR
spectra were recorded on either a Varian EM360L or a JEOL
FX-90Q spectrometer. Elemental analyses were performed
with a 240C analyzer.
* Corresponding author. Tel.: q86-551-3603301; fax: q86-551-
3631760; e-mail: zxwang@ustc.edu.cn
0277-5387/00/$ - see front matter q2000 Elsevier Science Ltd All rights reserved.
PII S0277-5387(00)00317-X
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2.1. Preparation of (m-PhSe)(m-R1S)[Fe2(CO)6]2(m4-S)
(2a, R1sMe; 2b, R1sPhCH2)
Anal. Found: C, 24.41; H, 1.32. Calc. for C15H8Fe4O12S2Se:
C, 24.13; H, 1.08%. 1H NMR (CCl4): d (ppm) 1.50 (t, Js7
Hz, 3H, Me), 2.16 (s, 3H, Me), 2.67 (q, Js7.5 Hz, 2H,
CH2). IR: n (cmy1) 2083m, 2057s, 2035vs, 2006s, 1992s,
1969s (Fe–CO).
A solution of the triethylammonium salt of [(m-PhSe)(m-
CO)Fe2(CO)6]y was generated by reacting 0.65 g (1.29
mmol) of Fe3(CO)12, 0.14 ml (1.32 mmol) of PhSeH and
0.19 ml (1.36 mmol) of Et3N in 30 ml of THF at room
temperature under nitrogen. The solution was cooled to
y788C, and 0.27 g (0.78 mmol) of (m-S2)Fe2(CO)6 was
added with stirring for 30 min at y788C. Subsequently 0.12
ml (1.93 mmol) of iodomethane was syringed. The mixture
was warmed to room temperature and stirred overnight. The
solvent was removed at reduced pressure and the residue
extracted with petroleum ether. After removal of the solvent,
the material remaining was subjected to filtration chromatog-
raphy (silica gel) using petroleum ether as eluent. The first
band gave 0.10 g (26% based on (m-S2)Fe2(CO)6) of (m3-
S)2Fe3(CO)9 as dark purple crystals. The second band gave
0.02 g (5% based on Fe3(CO)12) of dark red crystalline (m-
PhSe)2Fe2(CO)6 and the third main band afforded 0.16 g
(26% based on (m-S2)Fe2(CO)6) of red crystalline 2a, m.p.
142–1448C. Anal. Found: C, 28.50; H, 0.89. Calc. for
C19H8Fe4O12S2Se: C, 28.72; H, 1.01%. 1H NMR (CCl4): d
2.3. Preparation of (m-PhSe)[m-R2C(O)S]-
[Fe2(CO)6]2(m4-S) (3a, R2sMe; 3b, R2sPh)
To a cooled solution of [Et3NH][(m-PhSe)(m-CO)-
Fe2(CO)6] generated from 0.82 g (1.61 mmol) of
Fe3(CO)12, 0.18 ml (1.70 mmol) of PhSeH and 0.24 ml
(1.71 mmol) of Et3N in about 30 ml of THF was added 0.44
g (1.28 mmol) of (m-S2)Fe2(CO)6 with stirring for 30 min
at y788C. Subsequently 0.20 ml (1.82 mmol) of acetyl
chloride was syringed. The mixture was warmed to room
temperature and stirred overnight. Work-up as described in
Section 2.1 gave 0.08 g (13% based on (m-S2)Fe2(CO)6)
of (m3-S)2Fe3(CO)9, 0.22 g (46% based on Fe3(CO)12) of
(m-PhSe)2Fe2(CO)6 and 0.08 g (8% based on (m-S2)-
Fe2(CO)6) of 3a as red crystals, m.p. 1308C (dec.). Anal.
Found: C, 29.38; H, 1.12. Calc. for C20H8Fe4O13S2Se: C,
1
29.20; H, 0.98%. H NMR (CCl4): d (ppm) 2.54 (s, 3H,
(ppm) 2.20 (s, 3H, Me), 7.26 (s, 5H, Ph). IR: n (cmy1
2083m, 2056s, 2031vs, 1993s, 1973s (Fe–CO).
)
Me), 7.20 (s, 5H, Ph). IR: n (cmy1) 2085m, 2054s, 2036vs,
1999s, 1988s, 1976s (Fe–CO); 1732w (MeCO).
A similar reaction was carried out, in which 1.30 mmol of
benzyl chloride was added to a solution of anion 1 prepared
from 1.43 mmol of Fe3(CO)12, 1.51 mmol of PhSeH and
1.50 mmol of Et3N followed by addition of 1.28 mmol of
(m-S2)Fe2(CO)6 giving, after similar work-up, 0.08 g (13%
based on (m-S2)Fe2(CO)6) of (m3-S)2Fe3(CO)9, 0.19 g
(25% based on Fe3(CO)12) of (m-PhSe)2Fe2(CO)6 and
0.14 g (13% based on (m-S2)Fe2(CO)6) of dark red crystals
of 2b, m.p. 1108C (dec.). Anal. Found: C, 34.33; H, 1.13.
A similar reaction, in which 0.16 ml (1.38 mmol) of ben-
zoyl chloride was added to a cooled solution of anion 1
(prepared from 1.57 mmol of Fe3(CO)12, 1.61 mmol of
PhSeH and 1.64 mmol of Et3N and then 1.37 mmol of
(m-S2)Fe2(CO)6), gave 0.11 g (16% based on (m-
S2)Fe2(CO)6) of (m3-S)2Fe3(CO)9, 0.08 g (17% based on
Fe3(CO)12) of (m-PhSe)2Fe2(CO)6 and 0.26 g (21% based
on (m-S2)Fe2(CO)6) of red crystals of 3b, m.p. 1408C
(dec.). Anal. Found: C, 34.06; H, 1.29. Calc. for
C25H10Fe4O13S2Se: C, 33.94; H, 1.14%. 1H NMR (CDCl3):
d (ppm) 7.18 (s, 5H, Ph), 7.34–7.46 (m, 3H, Ph), 7.97–
8.09 (m, 2H, Ph). IR: n (cmy1) 2085m, 2052s, 2039vs,
2000s (Fe–CO); 1681m (PhCO).
1
Calc. for C25H12Fe4O12S2Se: C, 34.48; H, 1.39%. H NMR
(CCl4): d (ppm) 3.60 (s, 2H, CH2), 7.03–7.23 (m, 10H,
Ph). IR: n (cmy1) 2082m, 2054vs, 2036vs, 2010s, 1999vs,
1990vs (Fe–CO).
2.2. Preparation of (m-EtSe)(m-MeS)[Fe2(CO)6]2(m4-S)
(2c)
2.4. Preparation of (m-EtSe)[m-Ph C(O)S]-
[Fe2(CO)6]2(m4-S) (3c)
A Schlenk tube was charged with 0.16 g (2.03 mmol) of
selenium powder, 30 ml of THF and 2.00 mmol of EtMgBr
in Et2O. The mixture was stirred at room temperature for 20
min. To the solution was added 0.90 g (1.78 mmol) of
Fe3(CO)12 and stirring was continued for 20 min, resulting
in a brown–red solution of [MgBr][(m-EtSe)(m-CO)-
Fe2(CO)6]. The solution was cooled to y788C, and 0.55 g
(1.60 mmol) of (m-S2)Fe2(CO)6 was added with stirring
for 30 min at y788C. Subsequently 0.20 ml (3.21 mmol) of
iodomethane was syringed. The mixture was warmedtoroom
temperature and stirred for 3 h. Work-up as described in
Section 2.1 gave 0.11 g (14% based on (m-S2)Fe2(CO)6)
of (m3-S)2Fe3(CO)9 and 0.13 g (11% based on (m-S2)-
Fe2(CO)6) of red crystalline complex 2c, m.p. 143–1468C.
The solution of [MgBr][(m-EtSe)(m-S){Fe2(CO)6}2-
(m4-S)] was prepared according to the same procedure and
scale as described in Section 2.2. To the cooled solution was
added 0.19 ml (1.64 mmol) of benzoyl chloride. The mixture
was warmed to room temperature and stirred overnight.
Work-up as described in Section 2.1 gave 0.07 g (9% based
on (m-S2)Fe2(CO)6) of (m3-S)2Fe3(CO)9 and 0.14 g (10%
based on (m-S2)Fe2(CO)6) of red crystalline 3c, m.p. 1408C
(dec.). Anal. Found: C, 30.41; H, 1.38. Calc. for
C21H10Fe4O13S2Se: C, 30.14; H, 1.20%. 1H NMR (CDCl3):
d (ppm) 1.53 (t, Js7 Hz, 3H, Me), 2.70 (q, Js7 Hz, 2H,
CH2), 7.30–7.70 (m, 3H, Ph), 7.90–8.25 (m, 2H, Ph). IR:
n (cmy1) 2085m, 2057s, 2036vs, 2000s, 1989vs (Fe–CO);
1681w (PhCO).
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715
2.5. Preparation of (m-PhSe)(m-PhS)[Fe2(CO)6]2(m4-S) (4)
0.50 g (1.64 mmol) of Cp(CO)2FeI at y788C with stirring.
The mixture was warmed to room temperature and stirred
overnight. Solvent was removed at reduced pressure and the
residue extracted with CH2Cl2:petroleum ether (1:9 v/v).
After removal of the solvent, the material remaining was
subjected to filtration chromatography (silica gel). Petro-
leum ether eluted a purple band which gave 0.09 g (12%
based on (m-S2)Fe2(CO)6) of (m3-S)2Fe3(CO)9. Further
elution with 2:8 v/v CH2Cl2:petroleum ether gave 0.13 g
(9% based on (m-S2)Fe2(CO)6) of complex 5b as black
crystals, m.p. 1428C (dec.). Anal. Found: C, 28.27; H, 1.37.
To a cooled solution of [Et3NH][(m-PhSe)(m-CO)-
Fe2(CO)6] generated from 0.78 g (1.53 mmol) of
Fe3(CO)12, 0.17 ml (1.61 mmol) of PhSeH and 0.23 ml
(1.64 mmol) of Et3N in about 30 ml of THF was added 0.42
g (1.22 mmol) of (m-S2)Fe2(CO)6 and the mixture was
stirred for 30 min at y788C. Subsequently 0.24 g (1.25
mmol) of PhN2BF4 was added. The mixture was warmed to
room temperature and stirred overnight. Work-up as
described in Section 2.1 gave 0.08 g (14% based on (m-
S2)Fe2(CO)6) of (m3-S)2Fe3(CO)9, 0.23 g (50% based on
Fe3(CO)12) of (m-PhSe)2Fe2(CO)6 and 0.07 g (7% based
on (m-S2)Fe2(CO)6) of red crystals of 4, m.p. 1758C (dec.).
Anal. Found: C, 33.35; H, 1.35. Calc. for C24H10Fe4O12S2Se:
1
Calc. for C21H10Fe5O14S2Se: C, 27.76; H, 1.11%. H NMR
(CDCl3): d (ppm) 1.50 (t, Js7.5 Hz, 3H, Me), 2.53 (q,
Js7.5 Hz, 2H, CH2), 5.10 (s, 5H, Ph). IR:n(cmy1)2074m,
2050s, 2026vs, 1996s, 1982s, 1967vs (Fe–CO).
1
C, 33.64; H, 1.18%. H NMR (CCl4): d (ppm) 7.22–7.62
(m, 10H, Ph). IR: n (cmy1) 2081m, 2057s, 2037vs, 1996s,
1976m (Fe–CO).
2.8. Crystal data and structure determination of complex 6
Black crystals of complex 6 were grown from a petroleum
ether–CH2Cl2 solution at 08C. Data were collected on a Sie-
mens P4 four-circle diffractometer using graphite-mono-
chromated Mo Ka radiation. Absorption correction was
applied using SADABS. The structure was solved by the
direct method and refined by full-matrix least-squares on F2
with anisotropic thermal parameters for non-hydrogen atoms
on a PC using SHELXS-86 and SHELXL-97 software pack-
ages, respectively [24,25]. A summary of crystal data and
refinement parameters is given in Table 1. Selected bond
distances and angles are listed in Table 2.
2.6. Preparation of (m-PhS)[m-Cp(CO)2FeS]-
[Fe2(CO)6]2(m4-S) (5a) and (m3-S)2Fe3(CO)8-
[PhSeFe(CO)2Cp] (6)
To a cooled solution of [Et3NH][(m-PhSe)(m-CO)-
Fe2(CO)6] generated from 0.86 g (1.69 mmol) of
Fe3(CO)12, 0.19 ml (1.80 mmol) of PhSeH and 0.25 ml
(1.79 mmol) of Et3N in 30 ml of THF was added 0.46 g
(1.34 mmol) of (m-S2)Fe2(CO)6 and the mixturewasstirred
for 30 min at y788C. Subsequently 0.41 g (1.35 mmol) of
Cp(CO)2FeI was added. The reaction mixture was warmed
to room temperature and stirred overnight. Solvent was
removed at reduced pressure and the residue extracted with
CH2Cl2:petroleum ether (1:9 v/v). After removal of the sol-
vent, the material remaining was subjected to filtration chro-
matography (silica gel). Petroleumetherelutedapurpleband
which gave 0.05 g (8% based on (m-S2)Fe2(CO)6) of (m3-
S)2Fe3(CO)9. The second band gave 0.05 g (10% based on
Fe3(CO)12) of (m-PhSe)2Fe2(CO)6. Further elution with
2:8 v/v CH2Cl2:petroleum ether gave 0.19 g (15% based on
(m-S2)Fe2(CO)6) of complex 5a as black crystals and 0.10
g (9% based on (m-S2)Fe2(CO)6) of black crystalline com-
plex 6. 5a: m.p. 1508C (dec.). Anal. Found: C, 31.38; H,
Table 1
Crystal data and refinement parameters for complex 6
Formula
M
C21H10Fe4O10S2Se
788.77
Crystal system
Space group
triclinic
P1 (no. 2)
¯
˚
a (A)
10.5626(10)
10.6168(10)
13.4368(12)
75.686(2)
70.409(2)
75.352(2)
1351.5(2)
2
˚
b (A)
˚
c (A)
a (8)
b (8)
g (8)
3
˚
U (A )
1
Z
1.32. Calc. for C25H10Fe5O14S2Se: C, 31.39; H, 1.05%. H
Crystal size (mm)
Radiation l (A)
0.18=0.16=0.16
0.71073
NMR (CDCl3): d (ppm) 5.08 (s, 5H, Cp), 7.20 (s, 5H, Ph).
IR: n (cmy1) 2076m, 2051s, 2027vs, 1973s (Fe–CO). 6:
m.p. 87–888C. Anal. Found: C, 31.63; H, 1.24. Calc. for
C21H10Fe4O10S2Se: C, 31.98; H, 1.28%. 1H NMR (CDCl3):
˚
Temperature (K)
Scan type
294(2)
v–2u
2umax (8)
55.06
d (ppm) 4.90 (s, 5H, Cp), 7.20 (s, 5H, Ph). IR: n (cmy1
2066s, 2039s, 2017vs, 1997vs, 1954m, 1947m (Fe–CO).
)
Total reflections
6109
Independent reflections
Reflections with I)2s(I)
Goodness-of-fit on F2
Final R indices (I)2s(I))
6106 (Rints0.0000)
4884
0.679
2.7. Preparation of (m-EtS)[m-Cp(CO)2FeS]-
[Fe2(CO)6]2(m4-S) (5b)
a
R1
wR2
0.0282
0.0814
0.441, y0.375
b
y3
˚
Largest differences peak and hole (e A
)
The solution of [MgBr][(m-EtSe)(m-S){Fe2(CO)6}2-
(m4-S)] was prepared according to the same procedure and
scale as described in Section 2.2. To the solution was added
a R1s8NNFoNyNFcNN/8NFoN.
b wR2s[8w(Fo yFc )2/8wFo
]
.
2
2
4 1/2
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Table 2
˚
Selected bond distances (A) and angles (8) for complex 6
Se(1)–C(16)
Se(1)–Fe(4)
Se(1)–Fe(1)
Fe(1)–S(1)
Fe(1)–S(2)
Fe(1)–Fe(2)
1.9415(19) Fe(2)–S(2)
2.2545(6)
2.2569(6)
2.5728(5)
2.2416(6)
2.2516(5)
1.714
2.4134(4)
2.4433(3)
2.2080(6)
2.2351(5)
2.6291(4)
Fe(2)–S(1)
Fe(2)–Fe(3)
Fe(3)–S(1)
Fe(3)–S(2)
Fe(4)–Cent a
Scheme 2.
C(16)–Se(1)–Fe(4) 99.76(6)
C(16)–Se(1)–Fe(1) 112.89(6)
Fe(4)–Se(1)–Fe(1) 114.556(13) Fe(3)–Fe(2)–Fe(1) 81.516(14)
S(2)–Fe(2)–S(1)
S(2)–Fe(2)–Fe(3) 55.130(15)
78.91(2)
worthy that the yields of (m-RSe)(m-R9S)[Fe2(CO)6]2-
(m4-S) were low and, for RsPh, the oxidation product
(m-PhSe)2Fe2(CO)6 was formed in low to moderate yield.
In addition, (m3-S)2Fe3(CO)9 was also obtained in each
reaction. Treatment of the reaction mixture of [(m-RSe)(m-
CO)Fe2(CO)6]y and (m-S2)Fe2(CO)6 with Cp(CO)2FeI
afforded pentanuclear complexes 5a and 5b. For RsPh,
an unexpected product, (m3-S)2Fe3(CO)8[Se(Ph)Fe-
(CO)2Cp] (6), was also isolated. The formation of complex
6 may arise from the reaction of (m3-S)2Fe3(CO)9 with
PhSeFe(CO)2Cp produced from Cp(CO)2FeI and excess
Et3NHqSePhy (Scheme 2).
S(1)–Fe(1)–S(2)
S(1)–Fe(1)–Se(1)
S(2)–Fe(1)–Se(1)
S(1)–Fe(1)–Fe(2)
S(2)–Fe(1)–Fe(2)
S(1)–Fe(2)–Fe(3)
S(2)–Fe(2)–Fe(1)
S(1)–Fe(2)–Fe(1)
80.36(2)
S(1)–Fe(3)–S(2)
79.29(2)
158.195(18) S(1)–Fe(3)–Fe(2) 55.396(17)
85.752(15) S(2)–Fe(3)–Fe(2) 55.236(16)
54.792(16) Fe(1)–S(1)–Fe(3) 99.51(2)
54.499(15) Fe(1)–S(1)–Fe(2) 72.138(17)
54.836(18) Fe(3)–S(1)–Fe(2) 69.768(17)
53.812(14) Fe(1)–S(2)–Fe(3) 98.40(2)
53.070(15) Fe(1)–S(2)–Fe(2) 71.689(18)
Se(1)–Fe(1)–Fe(2) 103.412(13) Fe(3)–S(2)–Fe(2) 69.634(18)
a Cent is the centroid of the Cp ring composed of carbon atoms C(11)–
C(15).
Both complexes (m3-S)2Fe3(CO)9 and (m-PhSe)2Fe2-
(CO)6 are known and were identified by elemental analyses
and by comparison of their melting points, IR and 1H NMR
(for the latter) spectra with those of authentic samples
[26,27].
3. Results and discussion
The synthesis and reactions of [(m-RSe)(m-S)-
{Fe2(CO)6}2(m4-S)]y are summarized in Scheme 1. Both
[Et3NH][(m-PhSe)(m-CO)Fe2(CO)6] and [MgBr][(m-
EtSe)(m-CO)Fe2(CO)6] were prepared by reported meth-
ods [12,14] and reacted readily with (m-S2)Fe2(CO)6 at
y788C, as indicated by gas evolution. Treatment of the reac-
tion mixture with electrophiles such as alkyl halides, acid
chlorides and PhN2BF4 gave neutral complexes of the type
(m-RSe)(m-R9S)[Fe2(CO)6]2(m4-S) (R9salkyl, acyl or
phenyl). Thus the expected anions 1 were formed. Similarly
to the reaction between [(m-RS)(m-CO)Fe2(CO)6]y and
(m-S2)Fe2(CO)6, the sulfur–sulfur bond of (m-S2)-
Fe2(CO)6 is cleaved by the iron-centered anions and the
m-CO ligand of [(m-RSe)(m-CO)Fe2(CO)6]y is replaced
by one of the sulfur atoms of (m-S2)Fe2(CO)6. It is note-
Complexes 2–4 are red solids and 5a and 5b are black
solids. They are air stable in the solid state, but slightly air
sensitive in solution. The new complexes 2–5 were charac-
terized by elemental analyses, IR and 1H NMR spectra. Their
IR spectra showed four to six terminal carbonyl absorption
bands in the range 2085–1969 cmy1. For complexes 3a–3c
the absorption bands of thiocarboxylato groups were also
1
observed. Their H NMR spectra all exhibited respective
organic group resonance signals. It is worthy of note that
complexes 2–5 can exist as only one isomer in which the two
substituents are bonded to the bridged Se and S atoms with
an equatorial type of bond. This is because the m4-S atom of
2–5 utilizes two axial bonds to attach both (m-RSe)-
Scheme 1.
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H.-B. Zheng et al. / Polyhedron 19 (2000) 713–718
717
Fig. 1. ORTEP representation of the molecular structure of complex 6. The thermal ellipsoids are drawn at the 20% probability level.
˚
Fe2(CO)6 and (m-R9S)Fe2(CO)6 units, respectively, and
because there are larger non-bonded repulsions between the
axial R (or R9) group and axial Fe(CO)3 group [28]. This
Fe2(CO)6 (average 2.374 A) [8] and (m-Se2)Fe2(CO)6
(average 2.364 A) [36].
˚
1
deduction can be verified by some of the H NMR spectra.
For example, the 1H NMR spectrum of 2c showed one quartet
at d 2.67 ppm for SeCH2 [29] and one singlet at d 2.16 ppm
for SCH3 [28]; the CH3C(O) group of 3a showed one singlet
at d 2.54 ppm [30] and the CH2Se group of 3c showed one
quartet at d 2.70 ppm [29].
Supplementary data
Supplementary data are available from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK (fax: q44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk) on request, quoting the deposition number
CCDC 134795.
Complex 6 was isolated as a black solid. Its IR spectrum
1
exhibited terminal carbonyl absorption bands and the H
NMR spectrum showed the presence of phenyl and cyclo-
pentadienyl groups. The C/H analytical data agree closely
with the calculated values for complex 5. From these analyt-
ical results it seems as if complex 6 was an isomer of complex
5. However, the chemical shift of the 1H NMR spectrum for
the Cp group (d 4.90 ppm) was close to that of an axial
Fe(CO)2Cp [31]. This would involve considerable non-
bonded repulsion between two axial groups. For this reason,
a single-crystal X-ray diffraction study was undertaken. The
result showed that complex 6 is a mono-substituted product
of (m3-S)2Fe3(CO)9 by Se(Ph)Fe(CO)2Cp (Fig. 1). The
skeletal structure is very similar to that of (m3-S)2Fe3(CO)9
[32], i.e. it consists of an open triangle of iron atoms
(Fe(1)Fe(2)Fe(3)) capped on each side by the two sulfur
ligands, and S2Fe3 is a distorted square pyramid.
Acknowledgements
We thank the Chinese Academy of Science and the Edu-
cational Ministry of China for financial support.
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