Reaction of N-(3-methyl-2-thienylmethylidene)aniline with diiron nonacarbonyl: Cyclometalation induced methyl migration, imidoyl complex formation, and hydrogenation

Article abstract of DOI:10.1016/S0022-328X(98)01225-X

The reaction of N-(3-methyl-2-thienylmethylidene)aniline with Fe₂(CO)₉ under mild conditions in anhydrous benzene gives ironcarbonyl organometallic products 2b, 2c, 5, and an organic product 4c. Complexes 2b and 2c are cyclometalated

Full text of DOI:10.1016/S0022-328X(98)01225-X

Journal of Organometallic Chemistry 579 (1999) 211–216
Reaction of N-(3-methyl-2-thienylmethylidene)aniline with diiron
nonacarbonyl: cyclometalation induced methyl migration, imidoyl
complex formation, and hydrogenation
Dong-Liang Wang a, Wen-Shu Hwang a,*, Liangshiu Lee b, Michael Y. Chiang b
a Department of Chemistry, National Dong Hwa Uni6ersity, Hualien, 974, Taiwan
b Department of Chemistry, National Sun Yat-Sen Uni6ersity, Kaohsiung, 804, Taiwan
Received 2 October 1998; received in revised form 19 December 1998
Abstract
The reaction of N-(3-methyl-2-thienylmethylidene)aniline with Fe2(CO)9 under mild conditions in anhydrous benzene gives
ironcarbonyl organometallic products 2b, 2c, 5, and an organic product 4c. Complexes 2b and 2c are cyclometalated
diironhexacarbonyl isomers, in which the methyl group has migrated from b- to b%- and a%-carbon of the thienyl ring, respectively.
Complex 5 is a triironnonacarbonyl cluster with an imidoyl ligand capped on the top of the three-iron plane and a hydrogen atom
bridged to two irons. The organic product 4c is a hydrogenated product of the original Schiff base. Single crystals of 2c and 5
were subjected to the X-ray diffraction analysis and their structures thus confirmed. © 1999 Elsevier Science S.A. All rights
reserved.
Keywords: N-(3-methyl-2-thienylmethylidene)aniline; Cyclometalation; Methyl migration; Imidoyl complex; Hydrogenation
1. Introduction
bond is forced to react with the metal center by proxim-
ity [3]. b-Alkyl migration [4] and metal insertion into
carbon–carbon single bond of cyclopentadiene [5] have
also been observed.
Although impressive advances have been made in
activating the carbon–hydrogen bonds of hydrocar-
bons, transition-metal-promoted activation of unreac-
tive carbon–carbon bonds remains one of the most
prominent challenges in organometallic chemistry.
Most of the reported cases of carbon–carbon bond
activation by transition-metal complexes involve
strained systems such as cyclopropane or cubane [1],
intramolecular ligand activation, or activated system
such as aromatic nitriles and alkyl-substituted cyclopen-
tadienes [2]. Those cases in which unstrained carbon–
carbon bonds are cleaved typically rely upon formation
of an h5-cyclopentadienyl or h6-arene ring, or an in-
tramolecular addition in which the carbon–carbon
We have reported recently on the reaction of N-(2-
thienylmethylidene)aniline (1) with Fe2(CO)9 [6]. Two
cyclometalated (m–h1: h2-thienyl; h1: h1(N))hexacarbo-
nyldiiron complexes, 2 and 3, and an organic product 4
were obtained (Scheme 1). The reaction involves a C–H
activation on the thienyl ring, a C–C coupling via the
methine carbon, and a hydrogenation of the imine
group. In order to study the other possible types of
coordination between the thienyl ring and iron centers,
we became interested in studying the reaction of b-
methyl blocked thienyl Schiff base. We report here the
interesting result of the reaction of a b-methyl blocked
thienyl Schiff base with diiron nonacarbonyl. Cy-
clometalation induced methyl migration, formation of
imidoyl triironnonacarbonyl cluster, and hydrogenation
of imine group are observed.
* Corresponding author. Fax: +886-38-662-528.
E-mail address: hws@ndhu.edu.tw (W.-S. Hwang)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01225-X

212
D.-L. Wang et al. / Journal of Organometallic Chemistry 579 (1999) 211–216
2. Results and discussion
The thienyl Schiff base N-(3-methyl-2-thienylmethyli-
dene)aniline (1c) reacts with diiron nonacarbonyl in
anhydrous benzene to give two isomeric cyclometalated
diiron complexes, 2b and 2c, a triiron cluster, 5, and an
organic product, 4c, as the major products (Scheme 2).
Isomeric products 2b and 2c are unseparable by usual
chromatography. Different reaction temperature led to
the variation of product ratio between isomers 2b and
2c as described in Section 3. The product ratio 2b/2c
decreases from 1/1 at temperature above 30°C to 0.36/1
at 25°C, to 0.25/1 at 20oC, and to 0.18/1 at 15°C. When
the reaction temperature was lowered down to 5°C,
pure complex 2c was obtained. No thermal interconver-
tion of the two isomers was found after refluxing in
benzene for 24 h.
Scheme 2.
The 1H-NMR spectrum of complex 2c shows the
absence of the methine proton (resonance at l 8.76
ppm in 1c), and a singlet methylene resonance appears
at l 4.39 ppm. In the aromatic region, two multiplet
appear at l 7.32 and 7.15 ppm, the integrated intensi-
ties clearly show that only six protons are left. Subtract-
ing all signals that characterize the complex 2c from the
spectrum of a mixture of 2b and 2c leave the spectrum
of complex 2b [6]. The IR spectrum of complex 2c
shows the absence of CꢀN stretching and the presence
of three sharp and intense CꢀO stretches appearing at
2068, 2028, and 1988 cm−1. The mass spectrum of 2c
shows the same spectral pattern as that of a mixture of
2b and 2c. Both cases show the same molecular weight
and the complete loss of six COs ligands sequentially,
in accordance with the formulated structures 2b and 2c.
A red prism crystal of 2c was subjected to a single-
crystal X-ray analysis. Crystal and data collection
parameters are shown in Table 1. An ORTEP diagram of
2c is shown in Fig. 1. Selected bond distances and bond
angles are tabulated in Table 2. It is readily seen that
C(2) of the thienyl ring is s bonded to Fe(1) with a
bond distance of 1.981(5) A. C(1) and C(2) are bonded
˚
to Fe(2) with bond distances of 2.276(5) and 2.149(5)
A, respectively. Hence, Fe(2) is bonded to thiophene by
the p bond between C(1) and C(2), and the bond
distance between C(1) and C(2) is lengthened to
1.422(7) A. The thienyl ring in the organic ligand serves
as a three-electron donor and bridges the two iron
centers. The bond distance from N(1) to C(6), 1.484(6)
A, is in the single bond range, while the bond distances
to Fe(1) and Fe(2) are 1.981(4) and 2.003(4) A, respec-
˚
˚
˚
˚
tively. Therefore, the nitrogen atom acts as another
Table 1
Crystal and data collection parameters for compounds 2c and 5
Compound
2c
5
Formula
fw
Cryst syst
Space group
a (A)
b (A)
C18H11NO6Fe2S
481
C21H11NO9Fe3S
620
Triclinic
P1 (No. 2)
7.629(2)
8.711(2)
15.459(4)
100.37(2)
103.32(2)
100.74(2)
955.1(5)
2
Triclinic
P1 (No. 2)
9.281(2)
9.318(1)
14.457(3)
85.68(1)
87.24(2)
77.08(1)
1214.4(4)
2
˚
˚
˚
c (A)
h (°)
i (°)
k (°)
3
˚
V (A )
Z
Dcalc (g cm−3
)
1.673
1.695
Cryst size (mm)
2qmax (°)
0.33×0.50×0.58
50.1
0.33×0.35×0.38
50.1
Scan type
ꢀ-2u
ꢀ-2u
No. of reflns measd:
total, unique
No. of obsd reflns
(I\3.00|(I))
No. of variables
F000
3622, 3382
4544, 4261
2513
2585
253
316
484.00
16.61
0.045
0.047
618.00
19.02
0.037
0.027
v, (Mo–Ka) (cm−1
R
Rw
)
Scheme 1.

D.-L. Wang et al. / Journal of Organometallic Chemistry 579 (1999) 211–216
213
Fig. 1. ORTEP diagram of compound 2c at the 50% probability level.
three-electron donor bridge in 2c complex. An iron–
˚
iron distance of 2.471(1) A is shorter than in normal
diiron complexes [7] but is in accordance with other
nitrogen-bridged diiron complexes [6,8]. The Fe(1)–N–
Fe(2) angle is 76.6(2)° and Fe(1)–C(2)–Fe(2) is
73.4(2)°. The compression of these two angles from the
tetrahedral value is a result of the ligand constrains of
double bridging, which also brings about the shorter
iron-iron distance. Except for the position of the methyl
group, the structure feature of complex 2c closely re-
sembles that of complex 2b, as explicated in our previ-
ous report [6]. Both complexes 2b and 2c are analogous
to that of nitrogen-containing organometallic com-
plexes reported by Baikie and Mills [8a] and also bears
some resemblance to Fe2(CO)6 complexes with bridging
h1:h2-vinyl, furyl, and thienyl ligands reported by
Seyferth [9].
Since the free Schiff base itself was stable to the
reaction condition, the iron center must be responsible
for the methyl migration leading to the formation of
products 2b and 2c. A plausible explanation can be
suggested as follows: upon coordination of the methine
nitrogen of the 3-methylthienyl Schiff base to one of the
iron centers, a cyclometalation-induced carbon–carbon
bond cleavage occurs between the methyl group and the
b-carbon of the thienyl ring to form a methyl–iron
intermediate with a stable five-membered metalacycle.
We tried to trap the presumed methyl-iron intermediate
but without success. However the cleaved methyl group
Fig. 2. ORTEP diagram of compound 5 at the 50% probability level.
migrates back and attacks the b%- or a%-carbon of the
thienyl ring, leading to the activation of the b%- or
a%-hydrogen. Finally, the methine carbon becomes a
methylene group by accepting the hydrogen that was
removed from the b%- or a%-carbon and the nitrogen
coordinates to another iron center concomitantly to
give the product 2c or 2b. The methyl migration process
might be similar to the iridium catalyzed ethyl migra-
tion reaction of 1,1-diethylcyclopentadiene reported by
Crabtree et al. [2k]. In their case, the driving force is the
formation of an ethylcyclopentadienyl–iridium–ethyl
intermediate.
The variation of the isomer ratio 2b/2c with different
reaction temperature might be attributed to the stability
of the initial cyclometalated intermediate. At higher
reaction temperature (above 30°C), the methyl group
migrates back and attacks randomly on b%- and a%-car-
bon of the thienyl ring resulted to obtain 2b and 2c in
equal quantity. At lower temperature (5°C), the methyl
group selectively attacks the nearby b%-carbon and end
up 2c isomer as the sole product.
The molecular structure of compound 5, determined
by a single-crystal X-ray diffraction analysis, is shown
in Fig. 2. Crystal and data collection parameters are
tabulated in Table 1. Selected bond distances and bond
angles are reported in Table 3. The crystal consists of
discrete molecular units of HFe3(3-methyl-2-thienyl–
CꢀN–Ph)(CO)9. All three iron interactions are within
Table 2
˚
Selected bond lengths (A) and bond angles (°) of compound 2c
˚
Fe(1)–Fe(2)
Fe(2)–C(2)
Fe(1)–C(2)
C(1)–C(2)
Fe(1)–N(1)–Fe(2)
2.471(1) Fe(2)–C(1)
2.149(5) Fe(2)–N(1)
1.981(5) Fe(1)–N(1)
1.422(7) C(6)–N(1)
2.276(5)
1.981(4)
2.003(4)
1.484(6)
73.4(2)
bonding distances (2.553(1), 2.532(1), and 2.739(1) A)
and define a nearly isosceles triangle. Each iron atom is
also bonded to three terminal carbonyl ligands. Of
these nine carbonyl ligands, three of the carbonyls
extend axially below the triiron plane, four of the
76.6(2)
Fe(1)–C(2)–Fe(2)

214
D.-L. Wang et al. / Journal of Organometallic Chemistry 579 (1999) 211–216
Table 3
˚
Selected bond lengths (A) and bond angles (°) of compound 5
Fe(1)–Fe(2)
Fe(2)–Fe(3)
Fe(2)–C(1)
2.553(1)
2.532(1)
2.070(5)
1.931(5)
57.03(3)
65.17(3)
112.5(3)
127.4(4)
68.2(3)
Fe(1)–Fe(3)
Fe(3)–N(1)
Fe(2)–N(1)
C(1)–N(1)
2.739(1)
1.960(4)
2.021(4)
1.394(6)
57.80(3)
79.2(2)
117.4(5)
134.1(4)
79.0(1)
107.9(3)
124.6(3)
70.3(1)
48.0(1)
52.8(1)
Fe(1)–C(1) 1.931(5) C(1)–N(1) 1.394(6)
Fe(2)–Fe(1)–Fe(3)
Fe(1)–Fe(2)–Fe(3)
Fe(1)–C(1)–N(1)
Fe(1)–C(1)–C(2)
Fe(2)–C(1)–N(1)
Fe(2)–N(1)–C(1)
C(1)–N(1)–C(16)
Fe(3)–N(1)–(16)
Fe(2)–Fe(3)–N(1)
Fe(1)–Fe(2)–N(1)
Fe(3)–Fe(1)–C(1)
Fe(3)–Fe(2)–C(1)
Fe(1)–Fe(3)–Fe(2)
Fe(1)–C(1)–Fe(2)
N(1)–C(1)–C(2)
Fe(2)–C(1)–C(2)
Fe(2)–N(1)–Fe(3)
Fe(3)–N(1)–C(1)
Fe(2)–N(1)–C(16)
Fe(1)–Fe(3)–N(1)
Fe(1)–Fe(2)–C(1)
Fe(2)–Fe(1)–C(1)
Fe(3)–Fe(2)–N(1)
72.0(3)
124.3(4)
126.6(3)
51.6(1)
73.8(1)
69.1(1)
49.4(1)
72.0(1)
carbonyls are equatorially disposed, while the remain-
ing two carbonyls intersect the triiron plane at an angle
of ca. 30° (–C(7) 34.5°; –C(15) 27.2°). The open face of
the Fe3(CO)9 cluster is capped by the triply bridging
imidoyl (–CꢀN–) group. The hydride ligand, which is
not shown in Fig. 2, bridges Fe(1) and Fe(3) centers
with the longest Fe–Fe separation. The bonding of the
triply bridging imidoyl group to the metal triangle
could be described as two s bonds, Fe(1)–C(1)=
622 consists with the formulated structure. The struc-
ture of complex 5 is analogous to that of triiron-
nonacarbonyl complex with
a
triply bridging
acetimidoyl ligand and an h2-hydride reported by
Kaesz et al. [11].
Complex 5 is stable in its solid state at room temper-
ature. However, prolonged stirring of the complex 5 in
n-hexane or in benzene at room temperature for several
days leads to the decomposition of the complex. Two
organic products, the original Schiff base 1c and com-
pound 4c, were recovered with a ratio of 2.5:1. Decom-
position reaction that proceeded in a deuterated
benzene gives a similar result and no any deuterated
organic product was found. At this stage, we have no
answer regarding to the source of hydrogen that leads
to the product 4c.
The absence of a methine proton but the presence of
a broad amine resonance and a doublet methylene
resonance at l 5.25 and l 4.40 ppm, respectively, in the
1H-NMR spectrum indicate that compound 4c is a
hydrogenated product of the original Schiff base 1c.
The elemental analysis and other spectral data includ-
ing the presence of an NH stretching at 3421 cm−1 and
the absence of a CꢀN stretching in its IR spectrum
confirm the structure of 4c. The hydrogenation of a CN
double bond normally requires more extreme condi-
tions, and there is no doubt that compound 4c arises as
a result of coordination of 1c to an iron carbonyl.
˚
1.931(5) and Fe(3)–N(1)=1.960(4) A, and a p bond,
˚
Fe(2)–C(1)=2.070(5) and Fe(2)–N(1)=2.021(4) A.
There is a slight twist about the C–N bond which is
correlated with an asymmetry in the bonding of the
bridging imidoyl group. The C–N bond length of
˚
1.394(6) A in the –CꢀN– group is between that of a
˚
C–N single bond (1.47 A) and of a CꢀN double bond
˚
(1.28 A) [10]. The lengthening of the CꢀN double bond
upon p coordination is attributed to the s donation
and back p bonding of the highly conjugated imidoyl
ligand. This C–N distance is longer than the corre-
˚
observed in
sponding distance of 1.344(2)
A
HFe3(MeCꢀNH)(CO)9 [11] but is shorter than that of
˚
1.415(11) A found in HOs3(HCꢀNPh)(CO)9 [12]. The
metal–metal distance of the hydrogen-bridged metal–
metal bond which is also bridged by the hetero-p group
could in part be responsible for this difference. The fact
that the disappearance of the methine proton resonance
and the appearance of a singlet resonance at −26.29
1
ppm in the H-NMR spectrum of complex 5 indicates
that the hydrogen of methine is removed and a bridging
metal hydride is formed. In its IR spectrum, the C–N
stretching frequency of 1342 cm−1 (relative to the
corresponding band at 1616 cm−1 in the free Schiff
base) is in agreement with the C–N bond length as
described above. There are four sharp and intense CꢀO
3. Experimental
Diiron nonacarbonyl was prepared by photolysis of
iron pentacarbonyl (Aldrich) in glacial acetic acid [13].
Solvents were dried (sodium/benzophenone, P4O10) and
distilled under nitrogen prior to use. All other chemi-
cals were reagent grade and used without purification.
The NMR spectra were recorded on a Varian VXR-300
stretches appearing at 2088, 2052, 2016 and 1972 cm−1
.
The mass spectrum also shows the complete loss of nine
COs successively, and the molecular ion peak at m/z

D.-L. Wang et al. / Journal of Organometallic Chemistry 579 (1999) 211–216
215
NMR spectrometer (1H, 299.95 MHz; 13C, 75.43 MHz).
Chemical shifts were referenced to TMS, and deuter-
ated acetone (Janssen) was used as a solvent and as a
second reference. Mass spectra were obtained from a
VG-Biotech Quattro 5022 spectrometer. IR spectra
were recorded from a Bio-Rad FTS-40 spectrometer.
Elemental analyses were performed using a Heraeus
CHNO rapid analyzer. Crystals for X-ray diffraction
were obtained from n-hexane solution. A single crystal
was mounted on a glass fiber, and the X-ray diffraction
intensity data were measured on a Rigaku AFC7S
diffractometer at room temperature.
yield). The orange band collected was further purified
by a 20 cm×20 cm×0.25 mm TLC plate (silica gel
60(MN)) with ethyl acetate/n-hexane (1/10) as an eluent
to give 181 mg of compound 4c (15% yield). Substantial
amounts of Fe3(CO)12 and trace amount of N-((4-
methyl-2-thienyl)methyl)aniline and N-((5-methyl-2-
thienyl)methyl)aniline also were collected.
Product ratio 2b/2c was found to be reaction temper-
ature dependent. If the reaction was proceeded at 30–
50°C, product ratio 2b/2c rises to 1/1 (products yield: at
30°C, compound 2a+2b, 16%; compound 5, 35%;
compound 4c, 15%; at 50°C, compound 2a+2b, 22%;
compound 5, 36%; compound 4c, 15%). Product ratio
2b/2c decreases to 0.25 at 20°C and to 0.18 at 15°C. At
5°C, compound 2c is the sole isomeric product (prod-
ucts yield: compound 2c, 12%; compound 5, 32%;
compound 4c, 13%). Reaction temperature higher than
50°C will cause the decrease of the yield of products 2a
and 2b.
3.1. Synthesis of N-(3-methyl-2-thienylmethylidene)-
aniline (1c)
The synthesis of Schiff base employed the normal
procedure of condensation in alcohol solution [14].
Equimolar quantities of 3-methyl-2-thiophenecarbox-
aldehyde (Aldrich, 5.0 g, 40 mmol) and aniline (E.
Merck, 4.5 g, 40 mmol) were heated at reflux in ethanol
(E. Merck, 100 ml) for 12 h. The solvent was removed
under vacuum. The residue was distilled with a Kugel-
rohr distillation apparatus under reduced pressure (0.1
mmHg). The orange–red compound 1c was obtained
1
Compound 2c: m.p. 105ꢀ106°C. H-NMR: l 7.29
(m, 3H), 7.15 (m, 3H), 4.39 (s, 2H), 2.43(s,3H). 13C-
NMR: l 211.3, 161.8, 159.5, 150.2, 129.9, 127.9, 126.8,
124.2, 115.2, 73.9, 19.2. IR(CHCl3) wCO: 2068, 2028,
1988 cm−1. MS(EI): m/e 481 (M+), 453 (M+ −CO),
425 (M+ −2CO), 397 (M+ −3CO), 369 (M+ −4CO),
341 (M+ −5CO), 313 (M+ −6CO), 201 (L+). Anal.
Calc. for Fe2C18H11NSO6: C, 44.91; H, 2.28; N, 2.91.
Found: C, 44.78; H, 2.30; N, 2.91. Compound 5: m.p.
134ꢀ135°C. 1H-NMR: l 7.30 (d, J=4.8 Hz, 1H), 7.23
(m, 2H), 7.16 (m, 3H), 6.59 (d, J=4.8 Hz, 1H), 1.77 (s,
3H), −26.29 (s, 1H). 13C-NMR: l 210.0, 156.1, 147.4,
138.2, 133.6, 131.1, 129.0, 128.6, 127.3, 125.5, 16.4. IR
(CHCl3) wCN: 1342 cm−1, wCO: 2088, 2052, 2016 and
1972 cm−1. MS(EI): m/e 622 (M+ +1), 621 (M+), 593
(M+ −CO), 565 (M+ −2CO), 537 (M+ −3CO), 509
(M+ −4CO), 481 (M+ −5CO), 453 (M+ −6CO), 425
(M+ −7CO), 397 (M−8CO),369 (M+ −9CO), 201
(L+), 200 (L+ −1). Anal. Calc. for Fe3C21H11NSO9:
C, 40.58; H, 1.77; N, 2.25. Found: C, 40.48; H, 1.79; N,
1
(7.22 g; 90% yield) at 185°C. H-NMR l 8.75 (s,1H),
7.58 (d, J=5.1 Hz, 1H), 7.39 (t, J=8.1 Hz, 2H),
7.21(m, 3H), 7.00 (d, J=4.8 Hz, 1H), 2.50 (s 3H).
13C-NMR l 152.9, 143.56, 132.1, 130.6, 130.0, 126.6,
122.0, 14.0. IR (CHCl3) wCꢀN: 1616 cm−1. MS (EI): m/z
201(M+), 200 (M+ H). Anal. Calc. for C12H11NS: C,
71.60; H, 5.51; N, 6.96. Found: C, 71.53; H, 5.53; N,
6.98.
3.2. Reaction of 1c with Fe2(CO)9 in benzene to gi6e
[v-N-(((2,3-p1;p2)-5-methyl-2-thienyl)methyl)-p1:p1-
(N)-anilino]hexacarbonyldiiron (2b), [v-N-(((2,3-p1;p2)-
4-methyl-2-thienyl)methyl)-p1:p1-(N)-anilino]hexacar-
bonyldiiron (2c), [v3- ((N-1-p)-phenyl-(3-methyl-2-
thienyl)-formidoyl-N,C)]nonacarbonyl-v-hydrido-
triangulo-triiron (5), and N-((3-methyl-2-thienyl)-
methyl)aniline (4c)
1
2.27. Compound 4c: H-NMR: l 7.17 (d, J=4.8 Hz,
1H), 7.10 (t, J=8.1 Hz, 2H), 6.83 (d, J=5.1 Hz, 1H),
6.78 (d, J=7.8 Hz, 2H), 6.50 (t, J=7.2 Hz, 1H), 5.42
(broad, 1H), 4.40 (d, J=4.2 Hz, 2H), 2.24 (s, 3H).
13C-NMR: l 149.5, 137.7, 134.2, 130.9, 129.7, 123.4,
117.7, 113.6, 41.9, 13.7. MS(EI): m/z 203 (M+). Anal.
Calc. for C12H13NS: C, 70.89; H, 6.44; N, 6.89. Found:
C, 70.78; H, 6.44; N, 6.86.
A total of 6.0 mmol of compound 1c in 30 ml of
anhydrous benzene was added gradually to a 70 ml of
anhydrous benzene solution containing 7.2 mmol of
Fe2(CO)9 in the dark under nitrogen, and the reaction
mixture was stirred for 20 h at 25°C. The residue was
filtered and the solvent was removed under reduced
pressure. The residue was separated by a 3.5 cm×40
cm height column (230–400 mesh ASTM silica gel (E.
Merck)) with ethyl acetate/n-hexane (1:20) as an eluent.
The red band produced 418 mg of a mixture of com-
pounds 2b and 2c (15% yield with 2b/2c=0.36/1). The
deep-red band produced 1347 mg of compound 5 (36%
3.3. Decomposition of [v3-((N-1-p)-phenyl-(3-methyl-2-
thienyl)formidoyl-N,C)] nonacarbonyl-v-hydrido-triang-
ulo-triiron (5)
The title complex was stirred in a n-hexane or ben-
zene solution at room temperature for several days. The

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D.-L. Wang et al. / Journal of Organometallic Chemistry 579 (1999) 211–216
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reaction mixture was filtered to remove the insoluble
precipitate and the filtrate was dried and separated to
give compounds 1c and 4c with a ratio of 2.5: 1. A
similar result was obtained if the decomposition reac-
tion was carried out in a deuterated benzene solution.
4. Supplementary material
Text of the X-ray crystal structure experimental de-
tails, tables of atomic coordinates, anisotropic displace-
ment parameters, and bond distances as well as angles
of 2c and 5 (34 pages) are available. Ordering informa-
tion is given on any current masthead page.
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Acknowledgements
Financial support from the National Science Council
(Taiwan, ROC) is gratefully acknowledged.
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