Novel reaction of complex salts [(μ-RE)(μ-CO)Fe2(CO)6][HNEt3] (E = S, Se) with Phosphaalkene t-Bu(Me3SiO)C=PSiMe3. Synthesis and spectroscopic and crystallographic characterization of butterfly Fe2EP clusters (μ-RE)[μ-t-Bu(Me3SiO)CHPH]Fe2(CO)6 (E = S, Se)

Article abstract of DOI:10.1021/om990331o

Reaction of complex salts [(μ-RE)(μ-CC))Fe₂(CO)₆][HNEt₃] (1, E = S, Se) with phosphaalkene t-Bu(Me₃SiO)C=PSiMe₃ (2) has been found to afford a series of new butterfly-shaped Fe₂-EP clusters of type [(μ-RE)[μ-t-Bu(Me₃SiO)CHPH]Fe₂(CO)₆ (3, RE = EtS; 4, n-PrS; 5, n-BuS; 6, t-BuS; 7, PhSe; 8, p-MeC₆H₄Se) in quite high yields. This type of cluster may exist as three isomers, namely, e(R)e(H), e(R)a(H), and a(R)a(H), which differ in whether the R group and H atom are attached to E and P atoms with an axial or an equatorial bond. Clusters 3-8 have been characterized by elemental analysis and ¹H, ³¹P, and ⁷⁷Se NMR spectroscopy, as well as for isomers 3e(R)a(H), 6e(R)a(H), 8e(R)e(H), and 8a(R)a(H) by single-crystal X-ray diffraction analyses. In addition, a possible reaction mechanism has been preliminarily suggested.

Full text of DOI:10.1021/om990331o

2700
Organometallics 1999, 18, 2700-2706
Novel Rea ction of Com p lex Sa lts
[(µ-RE)(µ-CO)F e2(CO)6][HNEt3] (E ) S, Se) w ith
P h osp h a a lk en e t-Bu (Me3SiO)CdP SiMe3. Syn th esis a n d
Sp ectr oscop ic a n d Cr ysta llogr a p h ic Ch a r a cter iza tion of
Bu tter fly F e2EP Clu ster s
(µ-RE)[µ-t-Bu (Me3SiO)CHP H]F e2(CO)6 (E ) S, Se)
Li-Cheng Song,*,† Guo-Liang Lu,† Qing-Mei Hu,† and J ie-Sun‡
Department of Chemistry, Nankai University, Tianjin 300071, China, and
Laboratory of Organometallic Chemistry at Shanghai Institute of Organic Chemistry,
Shanghai 200032, China
Received May 4, 1999
Reaction of complex salts [(µ-RE)(µ-CO)Fe2(CO)6][HNEt3] (1, E ) S, Se) with phosphaalkene
t-Bu(Me3SiO)CdPSiMe3 (2) has been found to afford a series of new butterfly-shaped Fe2-
EP clusters of type [(µ-RE)[µ-t-Bu(Me3SiO)CHPH]Fe2(CO)6 (3, RE ) EtS; 4, n-PrS; 5, n-BuS;
6, t-BuS; 7, PhSe; 8, p-MeC6H4Se) in quite high yields. This type of cluster may exist as
three isomers, namely, e(R)e(H), e(R)a(H), and a(R)a(H), which differ in whether the R group
and H atom are attached to E and P atoms with an axial or an equatorial bond. Clusters
1
3-8 have been characterized by elemental analysis and H, 31P, and 77Se NMR spectroscopy,
as well as for isomers 3e(R)a(H), 6e(R)a(H), 8e(R)e(H), and 8a(R)a(H) by single-crystal X-ray
diffraction analyses. In addition, a possible reaction mechanism has been preliminarily
suggested.
In tr od u ction
studied and successfully utilized in the synthesis of
Fe-E cluster complexes containing a great variety of
organic and inorganic bridging groups.1-8 Furthermore,
the compounds containing phosphorus-carbon multiple
bonds,9 such as phosphaalkyne t-BuCtP10 and phos-
phaalkene t-Bu(Me3SiO)CdPSiMe3,11 have also been
extensively studied and up to now have become impor-
tant synthons for phosphorus-containing organic and
organometallic compounds. However, to our knowledge,
only one example is so far reported concerning the
reaction of complex salts 1 with the compounds contain-
ing phosphorus-carbon multipe bonds, in which the E
In recent years the complex salts [(µ-RE)(µ-CO)Fe2-
(CO)6][HNEt3] (1, E ) S, Se) have been intensively
† Nankai University.
‡ Laboratory of Organometallic Chemistry.
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402. (b) Song, L.-C.; Liu, J .-T.; Wang, J .-T.; Chem. J . Chin. Univ. 1989,
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J .-T. Acta Chim. Sin. 1990, 48, 110. (e) Song, L.-C.; Li, Y.; Hu, Q.-M.;
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5437.
10.1021/om990331o CCC: $18.00 © 1999 American Chemical Society
Publication on Web 06/17/1999

Butterfly Fe2EP Clusters (E ) S, Se)
Organometallics, Vol. 18, No. 14, 1999 2701
Ta ble 1. 1H{31P } a n d 31P NMR Da ta for P r od u cts 3-8
31P NMR (CDCl3)
product
1H{31P} NMR (CDCl3) δ (ppm), J (Hz)
δ (ppm)
3e(R)e(H)
3e(R)a(H)
4e(R)e(H)
4e(R)a(H)
0.18 (s,9H,SiMe3), 0.95 (s,9H,t-Bu), 1.35 (t,J )7.3,3H,CH3),
2.46 (q,J )7.3,2H,SCH2), 3.83 (dd,2J PH)11.5,J HH)6.3,1H,CH),
4.45 (dd,1J PH)360.2,J HH)6.3,1H,PH)
0.20 (s,9H,SiMe3), 1.06 (s,9H,t-Bu), 1.33 (t,J )7.4,3H,CH3), 2.45
(q,J )7.4,2H,SCH2), 2.63 (dd,1J PH)350.4,J HH)10.4,1H,PH), 4.15
(dd,2J PH)13.6,J HH)10.4,1H,CH)
92.74(s)
88.08(s)
92.89(s)
88.32(s)
0.18 (s,9H,SiMe3), 0.95 (s,9H,t-Bu), 1.03 (t,J )7.1,3H,CH3), 1.59-1.79
(m,2H,CH2), 2.43 (t,J )7.2,2H,SCH2), 3.84
(dd,2J PH)12.5,J HH)6.3,1H,CH), 4.45 (dd,1J PH)359.7,J HH)6.3,1H,PH)
0.20 (s,9H,SiMe3), 1.01 (t,J )7.3,3H,CH3), 1.06 (s,9H,t-Bu),
1.59-1.79 (m,2H,CH2), 2.42 (t,J )7.3,2H,SCH2),
2.61 (dd,1J PH)350.2,J HH)10.4,1H,PH),
4.14 (dd,2J PH)13.6,J HH)10.4,1H,CH)
5e(R)e(H)
5e(R)a(H)
0.18 (s,9H,SiMe3), 0.92 (t,J )7.2,3H,CH3), 0.95 (s,9H,t-Bu),
1.37-1.48 (m,2H,CH2CH3), 1.57-1.73 (m,2H,SCH2CH2),
2.44 (t,J )7.5,2H,SCH2), 3.83 (dd,2J PH)11.5,J HH)6.3,1H,CH),
4.44 (dd,1J PH)359.7,J HH)6.3,1H,PH)
92.87(s)
88.35(s)
0.20 (s,9H,SiMe3), 0.90 (t,J )7.3,3H,CH3), 1.06 (s,9H,t-Bu),
1.33-1.47 (m,2H,CH2CH3), 1.55-1.69 (m,2H,SCH2CH2),
2.43 (t,J )7.3,2H,SCH2), 2.63 (dd,1J PH)350.3,J HH)10.4,1H,PH),
4.14 (dd,2J PH)13.5,J HH)10.4,1H,CH)
6e(R)e(H)
6e(R)a(H)
0.18 (s,9H,SiMe3), 0.96 (s,9H,t-Bu), 1.37 (s,9H,t-BuS),
90.13(s)
87.34(s)
3.93 (dd,2J PH)10.5,J HH)6.3,1H,CH),
4.40 (dd,1J PH)353.5,J HH)6.3,1H,PH)
0.20 (s,9H,SiMe3), 1.06 (s,9H,t-Bu), 1.39 (s,9H,t-BuS),
2.39 (dd,1J PH)359.7,J HH)10.4,1H,PH),
4.15 (dd,2J PH)12.5,J HH)10.4,1H,CH)
7e(R)e(H)/
a(R)a(H)
0.20,0.26 (2s,9H,SiMe3), 1.00,1.05 (2s,9H,t-Bu),
3.11,4.73 (2dd,1J PH)359.24,J HH)10.0;1J PH)365.96,J HH)6.64,1H,PH),
4.03-4.19 (m,1H,CH), 7.33-7.52 (m,5H,Ph)a
95.61(s)
101.91(s)
8e(R)e(H)
8a(R)a(H)
0.22 (s,9H,SiMe3), 0.99 (s,9H,t-Bu), 2.29 (s,3H,CH3),
3.71-3.90 (m, 1H,CH), 4.66 (dd,1J PH)359.7,J HH)7.3,1H,PH),
7.16 (q, AA′BB′, J )8.1,4H,C6H4)
0.18 (s,9H,SiMe3), 0.96 (s,9H,t-Bu), 2.28 (s,3H,CH3),
3.09 (dd,1J PH)364.94,J HH)9.4,1H,PH), 3.98-4.16 (m,1H,CH),
7.04 (q,AA′BB′,J )7.6,4H,C6H4)
95.89(s)
102.19(s)
a
Measured in acetone-d6.
Sch em e 1
atom of complex salts 1 is sulfur and the phosphorus
compound is a phosphaalkene.6 To further explore the
reactivity of the complex salts 1 (E ) S, Se) toward
phosphaalkenes and to prepare organometallic com-
plexes containing both Fe-E and P-C structural units,
we initiated a study on the reaction of 1 (E ) S, Se)
with another type of phosphaalkene, t-Bu(Me3SiO)Cd
PSiMe3 (2). In this article we report the interesting
results concerning this study.
In principle, clusters 3-8 each might exist as four
isomers e(R)e(H), e(R)a(H), a(R)a(H), and a(R)e(H)
(Scheme 2), which differ in whether the R group and H
Resu lts a n d Discu ssion
Syn th esis via Rea ction of 1 w ith 2 a n d Ch a r a c-
ter ization of (µ-RE)[µ-t-Bu (Me3SiO)CHP H]Fe2(CO)6
(3-8). As described in the Experimental Section a
benzene solution of complex salt 1 (RE ) EtS) was
prepared from Fe3(CO)12, EtSH, and NEt3 in benzene
at 35-40 °C. The IR spectrum of 1 (RE ) EtS) in this
benzene solution showed a strong µ-CO peak at 1635
cm-1, which is somewhat different from that at 1743
cm-1 displayed by its THF solution.1,5 To the prepared
benzene solution was added 0.5 equiv of phosphaalkene
2, and then the mixture was stirred at 45-50 °C for 8
h. After TLC separation, a butterfly-shaped Fe2EP (E
) S) cluster (µ-RE)[µ-t-Bu(Me3SiO)CHPH]Fe2(CO)6 (3,
RE ) EtS) was obtained in 90% yield. Similarly, the
other five Fe2EP (E ) S, Se) clusters (µ-RE)[µ-t-Bu(Me3-
SiO)CHPH]Fe2(CO)6 (4-8, RE ) n-PrS; n-BuS; t-BuS;
PhSe; p-MeC6H4Se) were produced in 32-84% yields
(Scheme 1).
Sch em e 2
atom are attached to the E atom and P atom in an
equatorial bond or an axial bond.12
(12) The isomer designation a ) axial and e ) equatorial is used:
Shaver, A.; Fitzpatrick, P. J .; Steliou, K.; Butler, I. S. J . Am. Chem.
Soc. 1979, 101, 1313.

2702 Organometallics, Vol. 18, No. 14, 1999
Song et al.
In fact, we obtained clusters 3-6 as two single
isomers e(R)e(H) and e(R)a(H), cluster 7 as a mixture
of two isomers e(R)e(H) and a(R)a(H), and cluster 8 as
two single isomers e(R)e(H) and a(R)a(H), respectively.
The isomers of type a(R)e(H) could not be obtained,
possibly due to great steric repulsion between the two
large axially bonded groups R and t-BuCH(OSiMe3). All
the obtained isomers for 3-6 and 8 and the isomer
mixture for 7 have been characterized by combustion
analysis and spectroscopy, as well as, for some, by X-ray
diffraction techniques. The 1H and 31P NMR spectral
data of these compounds are presented in Table 1.
1
According to the H NMR data of SCH2 in clusters 3-5
and t-BuS in cluster 6, it seems to be reasonable that
the R groups of 3-5 and 6 are bonded to the S atom
through an equatorial type of bond.8m-k Fortunately, for
3 and 6 this assignment has been confirmed by X-ray
diffraction analyses of isomers 3e(R)a(H) and 6e(R)a-
1
(H) (see below). As for 7 and 8, since the H NMR data
of R (phenyl and tolyl) groups are complicated, we
cannot establish whether such groups are attached to
the Se atom by an axial or equatorial bond. However,
for 8 the X-ray diffraction analysis has indicated that
in its one isomer, i.e., 8e(R)e(H), the tolyl group is
bonded to the Se atom by an equatorial bond and in
another isomer, i.e., 8a(R)a(H), by an axial bond (also
see below). In addition, since the 31P NMR spectral data
of the two isomers of 7 (95.61 and 101.91 ppm) are
almost the same as those of the two isomers of 8 (95.89
and 102.19 ppm), we might conclude that 7 consists of
the same type of isomers, i.e., 7e(R)e(H) and 7a(R)a-
(H).
1
In addition, we can see from the H NMR data that
the chemical shifts of the H atom axially bonded to the
P atom are at much higher field than those of the H
atom equatorially bonded to the P atom; the δe-PH for
e(R)e(H) isomers are generally in the range 4.40-4.73
ppm, and the δa-PH for e(R)a(H) and a(R)a(H) isomers
are in the range 2.39-3.09 ppm. These points men-
tioned above can be more clearly seen from correspond-
1
ing H{31P} NMR spectra of 3e(R)e(H) and 3e(R)a(H)
(Figure 1). In Figure 1, the two dd-type quartets at 4.45
and 2.63 ppm can be assigned to the equatorially bonded
H atom and axially bonded H atom in the PH group of
3e(R)e(H) and 3e(R)a(H), respectively.
1
F igu r e 1. Partial H{31P} NMR spectra of 3e(R)e(H) and
3e(R)a(H).
These dd-type of quartets are apparently generated
by joint coupling of the 31P nucleus and the H atom in
the neighboring CH group. In addition, the H atom of
the neighboring CH group can also be coupled with the
31P nucleus and the H atom of the PH group to give
another two dd-type quartets at 3.83 and 4.15 ppm
assigned to the H atom in the CH group of 3e(R)e(H)
and 3e(R)a(H), respectively. It is worth noting that the
coupling constants for these two isomers between 31P
ppm, respectively, following the trend of a(R)a(H) >
e(R)e(H) > e(R)a(H). Such 31P NMR values are close to
those of reported compounds, such as (µ-PhPH)(µ-η5-
C5H5Fe(CO)2PhP)Fe2(CO)6 (97.0 ppm)13 and (µ-PhP-
PPh-µ)[(µ-PhPH)Fe2(CO)6]2 (81.2 ppm).14
We determined the 77Se NMR spectra of 8e(R)e(H),
8a(R)a(H), and a mixture of 7e(R)e(H) and 7a(R)a(H).
The spectrum of 8e(R)e(H) shows a doublet at 237.7 ppm
(2J PSe ) 33.7 Hz), and that of 8a(R)a(H) displays a
doublet at 191.7 ppm (2J PSe ) 97.2 Hz). Similarly, the
77Se NMR spectrum of the isomer mixture of 7e(R)e(H)
and 7a(R)a(H) (Figure 2) shows two doublets charac-
teristic of their two bridged Se atoms. The doublet at
243.1 ppm (2J PSe ) 35.4 Hz) is assigned to the Se atom
attached to the equatorial phenyl group in isomer 7e-
(R)e(H), whereas that at 195.9 ppm (2J PSe ) 93.8 Hz) is
attributed to the Se atom attached to an axial phenyl
group in isomer 7a(R)a(H). It is apparent that such 77Se
1
and its directly linked H atom, namely, J 1H{31P} are
350.2 and 360.2 Hz, which are similar to those reported
13
for (µ-PhPH)(µ-η5-C5H5Fe(CO)2PhP)Fe2(CO)6 and (µ-
PhP-PPh-µ)[(µ-PhPH)Fe2(CO)6]2.14
The 31P NMR spectral data of 3-8 indicate that the
31P chemical shifts for isomers e(R)e(H), e(R)a(H), and
a(R)a(H) are in the range 90-96, 84-88, and 101-103
(13) Seyferth, D.; Henderson, R. S.; Wood, T. G. Recl. Trav. Chim.
Pays-Bas 1988, 107, 134.
(14) Seyferth, D.; Wood, T. G.; Henderson, R. S. J . Organomet. Chem.
1987, 336, 163.

Butterfly Fe2EP Clusters (E ) S, Se)
Organometallics, Vol. 18, No. 14, 1999 2703
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 8e(R)e(H) a n d 8a (R)a (H)
8e(R)e(H)
8a(R)a(H)
Fe(1)-Fe(2)
Fe(1)-Se
Fe(1)-P
2.5761(8)
2.3983(5)
2.2316(9)
1.935(3)
1.890(3)
2.587(1)
2.3807(9)
2.213(1)
1.944(4)
1.871(4)
Se-C(7)
P-C(14)
Fe(2)-Fe(1)-Se
Fe(2)-Fe(1)-P
Se-Fe(1)-P
Fe(1)-Se-Fe(2)
Fe(1)-P-Fe(2)
Fe(1)-Se-C(7)
Fe(1)-P-C(14)
57.36(2)
57.35(3)
53.96(4)
81.65(4)
65.66(3)
71.72(4)
112.9(1)
127.4(1)
54.47(3)
77.89(3)
65.06(2)
70.69(3)
113.43(9)
123.15(9)
F igu r e 2. 77Se NMR spectrum of a mixture of 7e(R)e(H)
and 7a(R)a(H).
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 3e(R)a (H) a n d 6e(R)a (H)
3e(R)a(H)
6e(R)a(H)
Fe(1)-Fe(2)
Fe(1)-S
Fe(1)-P
S-C(15)
P-C(7)
2.5617(6)
2.271(1)
2.2244(8)
1.832(3)
1.870(3)
2.5611(9)
2.260(1)
2.231(1)
1.875(3)
1.873(3)
Fe(2)-Fe(1)-S
Fe(2)-Fe(1)-P
S-Fe(1)-P
Fe(1)-S-Fe(2)
Fe(1)-P-Fe(2)
Fe(1)-S-C(15)
Fe(1)-P-C(7)
55.61(3)
54.84(2)
75.27(3)
68.70(2)
70.31(3)
114.6(1)
126.84(9)
55.69(3)
54.79(3)
74.27(4)
68.89(3)
70.17(3)
122.0(1)
130.1(1)
F igu r e 3. ORTEP drawing of 3e(R)a(H) with atom-
labeling scheme.
NMR spectral data are comparable with those of similar
Fe2Se2 butterfly complexes.15,16
Cr ysta l Molecu la r Str u ctu r es of 3e(R)a (H), 6e-
(R)a (H), 8e(R)e(H), a n d 8a (R)a (H). To unambigu-
ously confirm the structures of the products isolated
from the above type of reactions, single-crystal X-ray
diffraction analyses for 3e(R)a(H), 6e(R)a(H), 8e(R)e(H),
and 8a(R)a(H) were undertaken. Tables 2 and 3 list the
selected bond lengths and angles. Figures 3-6 show
their molecular structures. As seen in Figures 3-6, each
molecule contains one S or Se atom and one P atom
bridged to the two Fe atoms of two Fe(CO)3 structural
units to construct a butterfly-shaped Fe2EP (E ) S, Se)
skeleton. In addition, while each molecule has one R
(Et, t-Bu, p-MeC6H4) group bonded to the E (E ) S, Se)
atom of the butterfly skeleton through an equatorial or
axial bond, it has one H atom and one t-Bu(Me3SiO)-
CH group attached to the P atom of the butterfly skele-
ton through corresponding equatorial and axial bonds.
F igu r e 4. ORTEP drawing of 6e(R)a(H) with atom-
labeling scheme.
The X-ray diffraction analyses indicated that the
dihedral angles between two wings of the isomers
increase in the order 6e(R)a(H) (94.59°) < 3e(R)a(H)
(96.04°) < 8e(R)e(H) (98.69°) < 8a(R)a(H) (104.65°). The
Fe(1)-Fe(2) bond lengths of the Fe2SP clusters of 3e-
(R)a(H) (2.5617(1) Å) and 6e(R)a(H) (2.5611(9) Å) are
very close to those of the Fe2SeP clusters of 8e(R)e(H)
(15) Song, L.-C.; Yan, C.-G.; Hu, Q.-M.; Sun, J .; Mao, X.-A. J . Coord.
Chem. 1996, 39, 147.
(16) Buchholz, D.; Huttner, G.; Zsolnai, L.; Imhof, W. J . Organomet.
Chem. 1989, 377, 25.

2704 Organometallics, Vol. 18, No. 14, 1999
Song et al.
Fe bond angles of 70.17-71.72° are about the same as
those of the reported Fe2SP clusters mentioned above
(2.194-2.233 Å, 70.6-72.6°). In addition, the P-C bond
lengths in these four isomers (1.87-1.89 Å) are reason-
able for a P-C single bond (1.79-1.99 Å)20 and very
close to that (average 1.879 Å) in a similar compound,
(µ-o-C6H4)(CH2PPh)2Fe2(CO)6.21
Mech a n ist ic Con sid er a t ion s. According to the
structures of products 3-8, the reaction between 1 and
2 would involve, at least, both addition of 1 toward the
PdC double bond of 2 and replacement of SiMe3 of 2 by
a proton. In fact, there were several reports about the
addition reaction toward a PdC double bond, such as
in the reaction of (Me3Si)2NPdCHSiMe3 with [(µ-EtS)-
(µ-CO)Fe2(CO)6][HNEt3]6 and the others.22 It was also
reported that Me3Si linked to the P atom of the PdC
double bond could be substituted by some electrophilic
groups, such as in the reactions of t-Bu(Me3SiO)Cd
PSiMe3 with t-BuCOCl to give t-BuC(O)PdC(t-Bu)-
(OSiMe3) and Me3SiPdC(NEt2)2 with Ph3YCl to give
Ph3YPdC(NEt2)2 (Y ) Si, Ge, Sn).23
On the basis of the above observations, we might
propose a mechanism to account for the formation of
cluster complexes 3-8, as shown in Scheme 3.
Sch em e 3
F igu r e 5. ORTEP drawing of 8e(R)e(H) with atom-
labeling scheme.
First, the iron-centered anion of 1 attacks the phos-
phorus atom of 2 to give a carbanion intermediate m 1.
Then, m 1 converts into another carbanion intermediate
m 2 through coordination of the P atom to another Fe
atom and concomitant loss of the µ-CO ligand. Finally,
3-8 would be produced via protonation of the two atoms
of the P-C bond and cleavage of the P-Si bond of
intermediate m 2 with counterion [HNEt3]+.
In terms of this reaction pathway, the two H atoms
in the PHCH unit of the products should originate from
the counterion [HNEt3]+ of the starting complex salts
1, which has been fortunately verified by the following
experiments. (i) When the Li+ salt of anion [(µ-EtS)(µ-
CO)Fe2(CO)6]-,2 instead of its [HNEt3]+ salt, was re-
acted with 2 in 2:1 molar ratio in benzene at room
temperature for 36 h and then at 35 °C for 24 h, the IR
F igu r e 6. ORTEP drawing of 8a(R)a(H) with atom-
labeling scheme.
(2.5761(8) Å) and 8a(R)a(H) (2.587(1) Å), and those of
other Fe2SP clusters such as (µ-C6H11S)(µ-Ph2P)Fe2-
(CO)6 (2.568(2) Å),17 (µ-PhS)(µ-Ph2P)Fe2(CO)6 (2.610(2)
Å),18 and (µ-t-BuS)(µ-PhClP)Fe2(CO)6(2.6017(9) Å).19 In
3e(R)a(H), 6e(R)a(H), 8e(R)e(H), and 8a(R)a(H), the
Fe-P bond lengths of 2.203-2.231 Å and the Fe-P-
(20) Emsley, J .; Hall, D. The Chemistry of Phosphorus; Harper &
Row Ltd.: London, 1976; p 34.
(21) Seyferth, D.; Wood, T. G.; Fackler, J . P., J r.; Mazany, A. M.
Organometallics 1984, 3, 1121.
(22) (a) Schmits, M.; Goller, R.; Regits, M. Synthesis 1997, 455. (b)
Miller, R. W.; Donaghy, K. J .; Spencer, J . T. Organometallics 1991,
10, 1161. (c) Klebach, Th. C. Lourens, R.; Bickelhaupt, F. J . Am. Chem.
Soc. 1978, 100, 4886. (d) Xie, Z. M.; Wisian-Neilson, P.; Neilson, R. H.
Organometallics 1985, 4, 339.
(23) (a) Breit, B.; Regitz, M. Chem. Ber. 1993, 126, 1945. (b) Becker,
G. Z. Anorg. Allg. Chem. 1977, 430, 66. (c) Markovskii, L. N.;
Romanenko, V. D.; Sarinapidvarko, T. V.; Povolotskii, M. I. J . Gen.
Chem. USSR 1985, 55, 194.
(17) Winter, A.; Zsolnai, L.; Huttner, G. J . Organomet. Chem. 1983,
250, 409.
(18) Le Borgne, G.; Mathieu, R. J . Organomet. Chem. 1981, 208, 201.
(19) Song, L.-C.; Wang, R.-J .; Li, Y.; Wang, H.-G.; Wang, J .-T. Youji
Huaxue 1989, 9, 512.

Butterfly Fe2EP Clusters (E ) S, Se)
Organometallics, Vol. 18, No. 14, 1999 2705
Syn th esis of (µ-n -P r S)[µ-t-Bu (Me3SiO)CHP H]F e2(CO)6
4e(R)e(H) a n d 4e(R)a (H). The same procedure as for 3e(R)e-
(H) and 3e(R)a(H) was followed, but 0.19 mL (2.1 mmol) of
n-PrSH was used instead of EtSH. A total of 0.189 g (35%) of
4e(R)e(H) was obtained as a red oil, and 0.268 g (49%) of 4e-
spectrum of the reaction mixture showed that the
intensity of the two peaks at 1671 and 1730 cm-1
characteristic of the µ-CO ligand of the Li+ salt2 was
only slightly decreased and very little product 3 was
obtained. (ii) If [(µ-EtS)(µ-CO)Fe2(CO)6]-Li+ was reacted
with 2 in 2:1 molar ratio in the presence of excess
[HNEt3]+Cl- under similar conditions, the IR spectrum
of the reaction mixture indicated that those two IR
peaks characteristic of the µ-CO disappeared completely
and isomers 3e(R)e(H) and 3e(R)a(H) were separated
in a total yield of 40%. (iii) Reaction of [(µ-RE)(µ-CO)-
Fe2(CO)6][HNEt3] (1) with 2 in 1:1 molar ratio gave
corresponding products in half of the yields obtained
from the standard reaction procedure (see Experimental
Section), which used a 2:1 molar ratio stoichiometry. So,
the 2:1 stoichiometry in the standard reaction procedure
for preparation of 3-8 is due to the need of two
[HNEt3]+ groups to provide two protons for each PdC
double bond.
(R)a(H) as an orange solid. 4e(R)e(H): Anal. Calcd for C17H27
-
Fe2O7PSSi: C, 37.38; H, 4.98. Found: C, 37.25; H, 4.97. IR
(film): νCtO 2062(vs), 2021(vs), 1982(vs) cm-1. 4e(R)a(H): mp
57-59 °C. Anal. Calcd for C17H27Fe2O7PSSi: C, 37.38; H, 4.98.
Found: C, 37.64; H, 4.89. IR (KBr): νCtO 2062(s), 2021(vs),
1985(vs), 1966(vs) cm-1
.
Syn th esis of (µ-n -Bu S)[µ-t-Bu (Me3SiO)CHP H]F e2(CO)6
5e(R)e(H) a n d 5e(R)a (H). The same procedure as for 3e(R)e-
(H) and 3e(R)a(H) was followed, but 0.23 mL (2.1 mmol) of
n-BuSH was used instead of EtSH. A total of 0.214 g (38%) of
5e(R)e(H) was obtained as a red oil, and 0.253 g (45%) of 5e-
(R)a(H) as an orange solid. 5e(R)e(H): Anal. Calcd for C18H29
-
Fe2O7PSSi: C, 38.59; H, 5.21. Found: C, 38.42; H, 4.98. IR
(film): νCtO 2062(vs), 2020(vs), 1980(vs) cm-1. 5e(R)a(H): mp
52-54 °C. Anal. Calcd for C18H29Fe2O7PSSi: C, 38.59; H, 5.21.
Found: C, 38.68; H, 5.12. IR (KBr): νCtO 2061(vs), 2020(vs),
1976(vs) cm-1
.
Exp er im en ta l Section
Syn th esis of (µ-t-Bu S)[µ-t-Bu (Me3SiO)CHP H]F e2(CO)6
6e(R)e(H) a n d 6e(R)a (H). The same procedure as for 3e(R)e-
(H) and 3e(R)a(H) was followed, but 0.24 mL (2.1 mmol) of
t-BuSH was used instead of EtSH. A total of 0.192 g (34%) of
6e(R)e(H) was obtained as a red oil, and 0.203 g (36%) of 6e-
Gen er a l Com m en ts. All reactions were carried out under
an atmosphere of highly prepurified nitrogen using standard
Schlenk techniques. Benzene was distilled under nitrogen from
sodium/benzophenone ketyl, while triethylamine from potas-
(R)a(H) as an orange solid. 6e(R)e(H): Anal. Calcd for C18H29
-
sium hydroxide. Mercaptans were of commercial origin and
Fe2O7PSSi: C, 38.59; H, 5.21. Found: C, 38.54; H, 5.25. IR
(film): νCtO 2057(vs), 2019(vs), 1979(vs) cm-1. 6e(R)a(H): mp
85-87 °C. Anal. Calcd for C18H29Fe2O7PSSi: C, 38.59; H, 5.21.
Found: C, 38.46; H, 4.92. IR (KBr): νCtO 2058(s), 2023(vs),
24
used without further purification. Fe3(CO)12
,
PhSeH,25
p-MeC6H4SeH,25 and t-Bu(Me3SiO)CdPSiMe326 were prepared
according to literature procedures.
Products were separated by thin-layer chromatography
(TLC glass plates of 20 × 25 × 0.25 cm coated with silica gel
G). The eluents, light petroleum ether, acetone, and methylene
chloride, were of reagent grade and were used as purchased.
The yields were calculated on the basis of phosphaalkene 2.
1982(vs), 1966(vs) cm-1
.
Syn th esis of (µ-P h Se)[µ-t-Bu (Me3SiO)CHP H]F e2(CO)6
(7). The same procedure as for 3e(R)e(H) and 3e(R)a(H) was
followed, but 0.33 mL (2.1 mmol) of PhSeH was used instead
of EtSH and the eluent was a mixture of acetone and light
petroleum ether (v/v ) 1:10). From the first, yellow major band
0.199 g (32%) of the mixture of 7e(R)e(H) and 7e(R)a(H) was
obtained as an orange solid. Anal. Calcd for C20H25Fe2O7-
PSeSi: C, 38.30; H, 4.01. Found: C, 38.51; H, 3.88. IR (KBr):
Melting points were determined on
a Yanaco MP-500
melting point apparatus. Elemental analyses were performed
on a Yanaco CORDER MT-3 analyzer. 1H NMR,31P NMR (with
85% H3PO4 as external standard), and 77Se NMR (relative to
Me2Se) spectra were recorded on a Brucker AC-P 200 NMR
spectrometer. IR spectra were obtained on a Nicolet FT-IR
170X spectrophotometer with KBr disk or liquid film.
νCtO 2057(s), 2021(vs), 2002(s), 1977(vs), 1959(s) cm-1 77Se
.
NMR (CDCl3): δ 195.9 (d, J P-Fe-Se ) 93.8 Hz), 243.1(d, J P-Fe-Se
) 35.4 Hz) ppm. The second, orange major band gave 0.200 g
(34%) of (µ-PhSe)2Fe2(CO)6.28
Syn th esis of (µ-EtS)[µ-t-Bu (Me3SiO)CHP H]F e2(CO)6
3e(R)e(H) a n d 3e(R)a (H). A 100 mL three-necked flask
equipped with a stir-bar, a N2 inlet tube, and a serum cap was
charged with 1.00 g (2.0 mmol) of Fe3(CO)12, 20 mL of benzene,
0.16 mL (2.1 mmol) of EtSH, and 0.32 mL (2.3 mmol) of Et3N.
The mixture was stirred at 35-40 °C for 0.5 h, during which
time the green solution turned red-brown. To the solution was
added 0.262 g (1.0 mmol) of phosphaalkene 2, and the reaction
mixture was stirred at 45-50 °C for 8 h. The resulting solution
was evaporated in vacuo, and the residue was separated by
TLC using light petroleum ether as eluent. The first band gave
a small amount of (µ-EtS)2Fe2(CO)6.27 From the second and
third yellow bands 0.152 g (29%) of 3e(R)e(H) and 0.324 g
(61%) of 3e(R)a(H) were respectively obtained, both as orange
solids. 3e(R)e(H): mp 45-47 °C. Anal. Calcd for C16H25Fe2O7-
PSSi: C, 36.11; H, 4.70. Found: C, 36.10; H, 4.56. IR (KBr):
νCtO 2062(vs), 2021(vs), 1980(vs) cm-1. 3e(R)a(H): mp 83-84
°C. Anal. Calcd for C16H25Fe2O7PSSi: C, 36.11; H, 4.70.
Found: C, 36.04; H, 4.70. IR (KBr): νCtO 2061(vs), 2022(vs),
Syn th esis of (µ-p-MeC6H4Se)[µ-t-Bu (Me3SiO)CHP H]-
F e2(CO)6 8e(R)e(H) a n d 8e(R)a (H). The same procedure as
for 3e(R)e(H) and 3e(R)a(H) was followed, but 0.360 g (2.2
mmol) of p-MeC6H4SeH was used instead of EtSH and the
eluent was a mixture of acetone and light petroleum ether (v/v
) 1:10). From the second, orange major band 0.237 g (38%) of
8i
(µ-p-MeC6H4Se)2Fe2(CO)6 was obtained. The first, yellow
major band, after further TLC separation, afforded 0.107 g
(17%) of 8a(R)a(H) from the front band and 0.233 g (36%) of
8e(R)e(H) from the other, both as orange solids. 8a(R)a(H): mp
95-97 °C. Anal. Calcd for C21H27Fe2O7PSeSi: C, 39.34; H, 4.24.
Found: C, 39.32; H, 4.27. IR (KBr): νCtO 2059(s), 2019(vs),
1999(s), 1981(s), 1970(vs), 1954(s) cm-1 77Se NMR (CDCl3):
.
δ 191.7 (d, J P-Fe-Se ) 97.2 Hz) ppm. 8e(R)e(H): mp 98-100
°C. Anal. Calcd for C21H27Fe2O7PSeSi: C, 39.34; H, 4.24.
Found: C, 39.34; H, 4.31. IR (KBr): νCtO 2061(vs), 2020(vs),
1991(vs), 1974(vs) cm-1 77Se NMR (CDCl3): δ 237.7 (d, J P-Fe-Se
.
) 33.7 Hz) ppm.
1985(vs) cm-1
.
X-r a y Cr ysta llogr a p h y of 3e(R)a (H), 6e(R)a (H), 8e(R)e-
(H), a n d 8a (R)a (H). Single crystals of 3e(R)a(H), 6e(R)a(H),
8e(R)e(H), and 8a(R)a(H) suitable for X-ray diffraction analyses
were grown by slow evaporation of their pentane solutions at
about 5 °C under nitrogen. A single crystal of 3e(R)a(H) with
(24) King, R. B. Organometallic Syntheses: Transition-Metal Com-
pounds; Academic Press: New York, 1965; Vol. I, p 95.
(25) Foster, D. G. Organic Syntheses; Wiley: New York, 1955; Collect
Vol. III, p 771.
(26) (a) Becker, G.; Gresser, G.; Uhl, W. Z. Naturforsch., B 1981,
36, 16. (b) Ro¨sch, W.; Hees, U.; Regitz, M. Chem. Ber. 1987, 120, 1645.
(27) De Beer, J . A.; Haines, R. J . J . Organomet. Chem. 1970, 24,
757.
(28) Schermer, E. D.; Baddley, W. H. J . Organomet. Chem. 1971,
30, 67.

2706 Organometallics, Vol. 18, No. 14, 1999
Song et al.
Ta ble 4. Cr ysta l Da ta a n d Str u ctu r a l Refin em en ts Deta ils for 3e(R)a (H), 6e(R)a (H), 8e(R)e(H), a n d
8a (R)a (H)
3e(R)a(H)
6e(R)a(H)
8e(R)e(H)
8a (R)a(H)
formula
fw
cryst syst
cryst size, mm
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C
52.18
16H25Fe2O7PSSi
C18H29Fe2O7PSSi
560.24
triclinic
0.20 × 0.20 × 0.30
P1h (No. 2)
12.035(4)
12.204(3)
10.763(4)
116.09(2)
111.11(3)
79.84(3)
1324.1(8)
2
C21H27Fe2O7PSeSi
641.15
triclinic
0.20 × 0.20 × 0.40
P1h (No. 2)
9.740(3)
16.116(7)
9.457(3)
90.38(3)
108.29(2)
97.28(4)
1396.5(9)
2
C21H27Fe2O7PSeSi
641.15
triclinic
0.20 × 0.20 × 0.30
P1h (No. 2)
11.528(2)
12.066(3)
10.538(3)
90.54(2)
93.76(2)
103.78(2)
1420.0(6)
2
triclinic
0.20 × 0.20 × 0.30
P1h (No. 2)
11.727(4)
13.448(3)
9.322(2)
94.28(2)
112.36(2)
111.90(2)
1220.6(7)
2
Z
D
calcd, g cm-3
1.448
1.405
1.525
1.499
F(000)
548
14.17
293
580
13.10
293
648
24.76
293
648
24.35
293
µ (Mo KR), cm-1
temp, K
wavelength, Å
scan type
2θmax, deg
no. of reflcns
no. of indep reflcns
Rint
0.71069
ω-2θ
0.71069
ω-2θ
0.71069
ω-2θ
0.71069
ω-2θ
50.9
49.9
50
50
3554
3314
0.036
3770
3529
0.046
4043
3728
0.025
4373
4103
0.024
no. of observns, n
no. of variables, p
R
2917
254
0.026
2901
359
0.027
3280
299
0.027
2882
299
0.030
Rw
0.036
0.032
0.034
0.034
goodness of fit
1.59
0.32
1.20
0.17
1.60
0.53
1.16
0.34
largest diff peak e Å-3
dimensions 0.20 × 0.20 × 0.30 mm was glued to a glass fiber
and mounted on a Rigaku AFC7R diffractometer with graphite-
monochromated Mo KR (λ ) 0.71069 Å) radiation and a 12
kW rotating anode generator. Data were collected at 20 °C
using the ω-2θ scan techniques to a maximum 2θ value of
50.9° and were corrected for Lp factors of the 3554 reflections,
of which 3314 were unique (Rint ) 0.036).
The structure was first solved by direct methods (SHELX
86) and then refined via full-matrix least-squares and Fourier
techniques (DIRDIF 92). The non-hydrogen atoms were refined
anisotropically, and hydrogen atoms were included but not
refined. The final cycle of the full-matrix least-squares refine-
ment was based on 2917 observed reflections (I > 3.00σ(I)) and
254 variable parameters and converged with unweighted and
weighted agreement factors of 0.026 (R) and 0.036 (Rw). The
maximum peak on the final difference Fourier map was 0.32
e/Å3. All calculations were performed using the TEXSAN
crystallographic software package of the Molecular Structure
Corporation.
The procedures for 6e(R)a(H), 8e(R)e(H), and 8a(R)a(H) are
similar. Crystal and refinement data for 3e(R)a(H), 6e(R)a-
(H), 8e(R)e(H), and 8a(R)a(H) are listed in Table 4.
Ack n ow led gm en t. We are grateful to the National
Natural Science Foundation of China, the State Key
Laboratory of Elemento-Organic Chemistry, and the
Laboratory of Organometallic Chemistry for financial
support of this work.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement parameters,
bond lengths and angles, and data collection and processing
parameters for 3e(R)a(H), 6e(R)a(H), 8e(R)e(H), and 8a(R)a-
(H). This material is available free of charge via the Internet
at http://pubs.acs.org.
OM990331O