A photochemical route to ferrocenyl-substituted ferrapyrrolinone complexes

Article abstract of DOI:10.1002/aoc.3805

In the presence of iron pentacarbonyl, photochemical reaction between phenylisocyanate and ferrocenylacetylene results in ferrapyrrolinone complex [Fe₂(CO)₆(μ₂-η³-FcC═C(H)C(O)NPh)] (1) and maleimide 3-ferrocenyl-1-phenyl-1H-pyrrole-2,5-dione (2). Under similar experimental conditions, ferrocenyl?/phenyl-substituted butadiyne primarily shows the activation of only one C?C bond and results in ferrapyrrolinone complexes [Fe₂(CO)₆(μ₂-η³-FcC═C(C?CR)C(O)NPh)] (3, R?=?Fc; 3a, R?=?Ph), maleimides 3-ferrocenyl-1-phenyl-4-(ferrocenylethynyl)-1H–pyrrole-2,5-dione (5) and 3-ferrocenyl-1-phenyl-4-(phenylethynyl)-1H–pyrrole-2,5-dione (5a) and [Fe₂(CO)₆(μ₂-η³-FcC═C(R)C(O)NPh)] (4; R?=?3-ferrocenyl-1-phenyl-1H-pyrrole-2,5-dione). Compound 4 consists of ferrapyrrolinone and a maleimide unit, formed by the activation of both C?C bonds of diferrocenylbutadiyne. Activation of both C?C bonds in a substituted butadiyne is a rare observation. Formation of the ferrapyrrolinone compounds is an advance over the earlier reported methods which generally use internal alkynes and involve prior synthesis of other clusters.

Full text of DOI:10.1002/aoc.3805

Received: 29 December 2016
DOI: 10.1002/aoc.3805
Revised: 6 February 2017
Accepted: 23 February 2017
F U L L PA P E R
A photochemical route to ferrocenyl‐substituted ferrapyrrolinone
complexes
1
1
2
1
Badri Nath Jha
| Abhinav Raghuvanshi | Raj Kumar Joshi | Shaikh M. Mobin |
1
Pradeep Mathur
1
School of Basic Sciences, Indian Institute of
Technology Indore, Khandwa Road, Indore
In the presence of iron pentacarbonyl, photochemical reaction between
4
2
53552, India
phenylisocyanate and ferrocenylacetylene results in ferrapyrrolinone complex
Department of Chemistry, Malaviya
3
[
Fe (CO) (μ ‐η ‐FcC═C(H)C(O)NPh)] (1) and maleimide 3‐ferrocenyl‐1‐phenyl‐
2
6
2
National Institute of Technology Jaipur,
Jaipur 302017, India
1H‐pyrrole‐2,5‐dione (2). Under similar experimental conditions, ferrocenyl−/phenyl‐
substituted butadiyne primarily shows the activation of only one C☰C bond and results
Correspondence
3
in ferrapyrrolinone complexes [Fe (CO) (μ ‐η ‐FcC═C(C☰CR)C(O)NPh)] (3,
2
6
2
Badri Nath Jha and Pradeep Mathur, School
of Basic Sciences, Indian Institute of
Technology Indore, Khandwa Road, Indore
R = Fc; 3a, R = Ph), maleimides 3‐ferrocenyl‐1‐phenyl‐4‐(ferrocenylethynyl)‐1H–pyr-
role‐2,5‐dione (5) and 3‐ferrocenyl‐1‐phenyl‐4‐(phenylethynyl)‐1H–pyrrole‐2,5‐dione
4
53552, India.
3
(
5a) and [Fe (CO) (μ ‐η ‐FcC═C(R)C(O)NPh)] (4; R = 3‐ferrocenyl‐1‐phenyl‐1H‐
2
6
2
Email: bnjha06@gmail.com;
director@iiti.ac.in
pyrrole‐2,5‐dione). Compound 4 consists of ferrapyrrolinone and a maleimide unit,
formed by the activation of both C☰C bonds of diferrocenylbutadiyne. Activation of
both C☰C bonds in a substituted butadiyne is a rare observation. Formation of the
ferrapyrrolinone compounds is an advance over the earlier reported methods which gen-
erally use internal alkynes and involve prior synthesis of other clusters.
KEYWORDS
bisferrole, ferrapyrrolinone complex, iron pentacarbonyl, maleimide, monoferrole
[
3]
1
| INTRODUCTION
alkyne or CO, respectively. In general, maleimides and
related compounds are synthesized by [2 + 2 + 1] co‐cycliza-
tion of heterocumulenic compounds such as carbodiimides or
Introduction of heteroatoms in organic ring compounds is
always fascinating to chemists because of the challenges in
their synthesis through organic synthesis routes and their
application in biologically active compounds. Metal cluster
complexes have been found to be powerful reagents for car-
[
8–10]
isocyanates with alkynes and CO.
In recent years our group has succeeded in the
activation of internal and terminal alkynes using metal car-
[
11–13]
bonyls.
In this regard, we have observed that reaction
[1,2]
bon–nitrogen bond formation.
When such efforts are
of alkyne with isocyanate in the presence of catalytic amount
of Fe(CO)5 leads to nitrogen‐containing heterocycles, i.e.
maleimide and hydantoin, under thermal conditions
made through the involvement of metal clusters, new and
interesting metal complexes can be formed. Such is the effort
for the formation of metallapyrrolinone complexes which
involves reaction of alkyne with face‐capped μ ‐nitrene metal
carbonyl cluster complexes or the reaction of complex
[14]
(Scheme 1).
Since the mode of activation of metal carbonyls and
3
[
15]
alkynes in photochemical
and thermal reactions is differ-
n
t
[Fe (μ‐CH )(CO) ] with phosphine imides (Bu ) P═NBu
ent, we extended our investigation and found that the same
reaction mixture responds differently under photochemical
conditions. In this contribution, a new method for the synthe-
sis of ferrapyrrolinone complexes using easily available
2
2
8
3
[3–7]
or Ph P═NPh under CO atmosphere.
metallapyrrolinone complexes can easily be converted to
pyridinone or maleimide derivatives by treating them with
These binuclear
3
Appl Organometal Chem. 2017;e3805.
wileyonlinelibrary.com/journal/aoc
Copyright © 2017 John Wiley & Sons, Ltd.
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https://doi.org/10.1002/aoc.3805

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JHA ET AL.
−
1
2
3
177–2190 cm represents C☰C in the case of compounds
13
and 3a. C NMR spectra of compounds 1, 3 and 3a show
peaks in the 207–210 and 167–172 ppm regions which are
attributed to the terminal carbonylic carbon bonded to the iron
atoms and metallacyclic carbonylic carbon, respectively.
Resonances in the 147–148 and 103–107 ppm regions are
SCHEME 1 Iron pentacarbonyl‐catalysed formation of maleimide
and hydantoin under thermal conditions
assigned to α‐ and β‐carbons (with respect to the Fe(CO) unit
3
of the ring) of the metallacycle, respectively, which are derived
from the added alkyne. Details of the spectral data are given in
the supporting information. There are three different isomeric
forms of ferrapyrrolinone complexes known, which differ in
the relative position of the imido and carbonyl groups in the
starting materials is described. This is an advance over the
previously reported methods where pre‐synthesis of either
imido‐capped clusters or methylene‐capped binuclear
complexes is required. Also, the contrasting behaviour of
internal and terminal acetylenes towards the formation of
ferrapyrrolinone complexes is discussed.
[6,7]
ring (Figure 1).
Interestingly, we have observed only type
I isomer in all products, probably because of more facile
coupling of carbon end of isocyanate and alkyne as well as
stronger nitrogen–iron bond.
2
| RESULTS AND DISCUSSION
Structures of 3 and 3a were further confirmed using sin-
gle‐crystal X‐ray diffraction (Figures 2 and 3). Compound 3
crystallizes with two independent but structurally similar mol-
ecules in the unit cell. Complexes 3 and 3a have similar
ferrapyrrolinone cores differing only in the substituents on
the α‐carbon of the metallapyrrolinone rings (3, R = C☰CFc;
Photolysis of ferrocenylacetylene, phenylisocyanate and iron
pentacarbonyl at 0 °C results in the predominantly separable
mixture of compounds 1 and 2 along with some other prod-
ucts (Scheme 2).
Reaction of diferrocenylbutadiyne with the same, under
similar conditions, gives compounds 3, 4 and 5 while the
reaction of ferrocenylphenylbutadiyne gives 3a and 5a
(Scheme 3).
Compounds 1, 3, 3a and 4 contain a ferrapyrrolinone ring
core. Thus, the formation of the ferrapyrrolinone complex is a
common observation with all three above‐mentioned alkynes.
Compounds 1, 2, 3, 3a, 4, 5 and 5a were characterized
using infrared (IR), NMR and mass spectrometric techniques.
Compounds 1, 3 and 3a show a stretching frequency
FIGURE 1 Isomers of ferrapyrrolinone complexes
−
1
around 1701–1713 cm
attributed to the metallacyclic
carbonyl group and that at 1999 to 2080 cm−1 for
terminal carbonyl stretching. Stretching frequency around
SCHEME 2 Photochemical reaction of ferrocenylacetylene with
phenylisocyanate and iron pentacarbonyl
FIGURE
2
Molecular structure of compound [Fe
2 6
(CO)
3
2
(μ ‐η ‐FcC═C(C☰CFc)C(O)NPh)] (3). Ellipsoids are drawn at 50%
probability level. Hydrogen atoms and other moieties are omitted for
clarity. Selected bond lengths (Å) and bond angles (°): Fe(3)–
C(2) = 1.971(9), Fe(3)–N(1) = 2.008(8), Fe(3)– Fe(4) = 2.475(2),
Fe(4)–N(1) = 1.997(7), Fe(4)–C(2) = 2.094(10), Fe(4)–C(1) =
2
.225(9), Fe(4)–C(25)
C(1)–C(2) = 1.392(12), C(1)–C(25) = 1.497(13), C(3)–C(4) =
.197(13); C(2)–Fe(3)–N(1) = 77.5(4), Fe(4)–N(1)–Fe(3) = 76.3(2),
= 2.484(10), N(1)–C(25) = 1.404(11),
1
SCHEME
3
Photochemical reaction of ferrocenyl−/phenyl‐
C(2)–C(1)–C(25) = 111.1(8), C(1)–C(2)–Fe(3) = 117.5(6), O(1)–
C(25)–N(1) = 124.7(9), N(1)–C(25)–Fe(4) = 53.5(4)
substituted butadiyne with phenylisocyanate and iron pentacarbonyl

JHA ET AL.
3 of 6
incorporating carbonyl group. Details of the spectral data are
given in the analytical data section (including Figure S1) in
the supporting information. The structure of compound 4
was also established using single‐crystal X‐ray diffraction.
Compound 4 can be visualized in two parts (Figure 4);
one part is a ferrapyrrolinone complex while the other is
an organic maleimide. The ferrapyrrolinone complex
part is similar to compound 3, except the substituent at α‐-
carbons of the metallapyrrolinone rings (3, R = C☰CFc;
4, R = 3‐ferrocenyl‐1‐phenyl‐1H‐pyrrole‐2,5‐dione (also
called maleimide)) and has similar interpretation of the
structure. The maleimide ring and ferrapyrrolinone rings
are not coplanar; the torsion angle between the two rings
is 63.59°. Maleimide ring and the phenyl ring bonded to
the nitrogen atom of the maleimide ring are also not in the
same plane, the torsion angle between these two rings
being 42.48°.
3
FIGURE 3 Molecular structure of compound [Fe
2
(CO)
6
(μ
2
‐η ‐
FcC═C(C☰CPh)C(O)NPh)] (3a). Ellipsoids are drawn at 50%
probability level. Solvent molecule is omitted for clarity. Selected
bond lengths (Å) and bond angles (°): Fe(1)–N(1) = 1.9973(14), Fe
(
2
1)–C(9) = 2.1110(16), Fe(1)–C(8) = 2.1973(16), Fe(1)–C(1) =
.4700(17), Fe(1)–Fe(2) = 2.4764(4), Fe(2)–N(1) = 1.9607(14),
Fe(2)–C(9) = 1.9760(16), N(1)–C(1) = 1.434(2), C(1)–C(8)
.494(2), C(8)–C(9) = 1.418(2), C(10)–C(11) = 1.200(2); C(9)–
=
IR spectra of compounds 2, 5 and 5a show ν in the range
CO
1713–1730 cm− corresponding to cyclic ketonic group.
1
1
Fe(1)–C(8) = 38.37(6), C(1)–N(1)–Fe(2) = 113.48(10), O(1)–C(1)–
N(1) = 125.18(15), O(1)–C(1)–C(8) = 128.47(15), N(1)–C(1)–C(8) =
06.11(13), C(9)–C(8)–C(1) = 111.17(14), C(8)–C(9)–Fe(2) =
Compounds 5 and 5a show stretching frequency in the range
1
13
2
177–2179 cm− indicating the presence of C☰C. Also
C
1
NMR spectra of all three compounds show peaks in the
1
15.88(12)
1
67–170 ppm region, representing ring carbonylic carbon.
Two peaks around 113–125 ppm represent the two vinyl car-
bons. Structures of compounds 2 and 5 were also established
using single‐crystal X‐ray diffraction (Figures 5 and 6). In
compound 2, C(3)─C(4) bond distance is 1.3350(3) Å
representing a bond order of 2. In compound 5, C(3)─C(4)
bond distance is 1.357(4) Å and C(5)─C(6) bond distance is
1.193(4) Å, representing a bond order of 2 and 3, respectively.
3
a, R = C☰CPh). The structure is stabilized by a single metal–
metal bond (3, 2.475(2) Å; 3a, 2.4764(4) Å) and bridging
μ ‐η ‐FcC═C(C☰CR)C(O)NPh ligand which derives from
the combination of the phenylisocyanate ligand and the added
alkyne. Each Fe atom is further coordinated by three CO
3
2
[
3]
ligands. In contrast to the ruthenium analogue,
the
ferrapyrrolinone ring in each of complexes 3 and 3a is not pla-
nar. Nitrogen atom is 13.90° above the average plane while CO
group is 4.86° below the average plane. The ferrapyrrolinone
carbonyl which arises from the added isocynate is not bonded
to either iron atom, whereas the nitrogen atom symmetrically
bridges both endo‐ and exocyclic iron atoms. C─C bond dis-
tances of the ring for 3 and 3a are 1.392(12) and 1.418(2) Å,
respectively, corresponding to a bond order of 1–2. This ole-
finic C─C segment is bonded to the binuclear iron carbonyl
unit as a σ,π‐vinyl ligand. Also, C(2) in 3a and C(9) in 3 in
each molecule is ca 0.12 Å closer to the Fe atom, to which it
is σ‐bonded, than it is to the Fe to which it is π‐bonded.
The IR spectrum of compound 4 shows stretching fre-
−1
quencies at 2077, 2049 and 2011 cm representing the
metal‐bound terminal carbonyls, stretching frequency at
3
FIGURE 4 Molecular structure of compound [Fe
FcC═C(R)C(O)NPh)] (R
2
(CO)
6
(μ
2
‐η ‐
−
1
=
3‐ferrocenyl‐1‐phenyl‐1H‐pyrrole‐2,5‐
dione) (4). Ellipsoids are drawn at 50% probability level. Hydrogen
atoms and solvent molecule are omitted for clarity. Selected bond
1
1
706 cm
representing metallacyclic carbonyl, and
−1
730 cm representing nonmetallacyclic carbonyl group.
−1
Absence of any IR peak around 2177–2179 cm shows the
absence of C☰C in the molecule, which indicates that both
C☰C bonds of diferrocenylbutadiyne have been consumed.
Preliminary investigation of its IR spectrum suggests that
compound 4 has two cores in the molecule: one core could
be a metallacyclic complex while other could be a unit
lengths (Å) and bond angles (°): Fe(1)–N(1)
Fe(1)–C(11) = 2.097(4), Fe(1)–Fe(2) = 2.5043(11), Fe(2)–N(1) =
.958(4), C(10)–C(11) = 1.413(6), N(1)–C(1) = 1.441(6), O(1)–
C(1) = 1.203(5), N(2)–C(8) = 1.398(6), C(12)–C(13) = 1.348(6),
C(11)–Fe(1)–Fe(2) 50.24(12), N(1)–Fe(2)–C(11) 78.23(17),
N(1)–Fe(2)–Fe(1) = 51.57(11)
=
2.003(4),
1
=
=

4
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JHA ET AL.
effects govern the exclusive formation of one of the two pos-
sible isomers in each case, since the group attached to the
pyrrolinone C is always more electron donating than that
β
[
16]
attached to C regardless of their size.
α
In the case of ferrocenylacetylene, compound 1
(ferrapyrrolinone complex) forms in no more than 10% yield,
while the yield of compound 2 is 10 to 15%. Low yield of
ferrapyrrolinone complex is not surprising, as
ferrocenylacetylene is known to undergo a competitive
formation of quinone and ferrole under photolytic
[
17]
conditions.
In the case of diferrocenylbutadiyne and
FIGURE 5 Molecular structure of compound 3‐ferrocenyl‐1‐phenyl‐
H‐pyrrole‐2,5‐dione (2). Ellipsoids are drawn at 50% probability level.
Selected bond lengths (Å) and bond angles (°): C(2)–C(3) = 1.470(3),
C(3)–C(4) = 1.335(3), C(1)–N(1)–C(2) = 109.77(15), C(1)–N(1)–
C(5) = 124.46(15), C(2)–N(1)–C(5) = 125.77(15), O(1)–C(1)–C(4) =
ferrocenylphenylbutadiyne, compounds 3 and 3a form in
major yields (65–70%). Yields of 4, 5 and 5a are between 10
1
3
and 15%. Compound [Fe (CO) (μ ‐η ‐FcC═C(R)C(O)
2
6
2
NPh)] (R = 1,3‐diphenyl‐1H‐pyrrole‐2,5‐dione) (4a) is not
observed. Possibly, in the case of phenylferrocenylbutadiene,
the C☰C bonded to electron‐rich ferrocenyl group is activated
more than the C☰C bonded to phenyl group.
1
1
1
28.73(17), N(1)–C(1)–C(4)
24.55(17), O(2)–C(2)–C(3)
06.35(15), C(4)–C(3)–C(2) = 110.08(17), C(3)–C(4)–C(11) = 129.02
=
=
106.02(15), O(2)–C(2)–N(1)
129.09(17), N(1)–C(2)–C(3)
=
=
In a new set of experiments, photolysis of compound 3 in
CO atmosphere gives compound 5 in 55% yield in 1 h. This
confirms that maleimide forms at the expense of
ferrapyrrolinone complex by demetallation and subsequent
insertion of carbon monoxide (Scheme 4). Similar conversion
was also reported with the ruthenapyrrolinone complex on
(18), C(10)–C(5)–N(1) = 119.62(16)
[
18]
extended photolysis (12 h).
Under photolytic conditions, in situ bubbling of carbon
monoxide for 2 h through a hexane solution of substituted
butadiyne, phenylisocyanate and iron pentacarbonyl resulted
in no increment of any of the above products, rather, the reac-
tion moves in a parallel and competing direction where for-
mation of monoferrole and bisferrole occurs without the
involvement of phenylisocyante. Formation of monoferrole
and bisferrole has been previously reported for the photo-
chemical reaction of substituted butadiyne and iron
[
19]
pentacarbonyl under CO atmosphere (Scheme 5).
FIGURE 6 Molecular structure of compound 3‐ferrocenyl‐1‐phenyl‐
In the case of butadiyne, it is a usual observation that only
one C☰C is activated while the other stays unreacted as a
4
‐(ferrocenylethynyl)‐1H–pyrrole‐2,5‐dione) (5). Ellipsoids are drawn at
5
0% probability level. Selected bond lengths (Å) and bond angles (°):
O(1)–C(1) = 1.204(4), N(1)–C(1) = 1.400(4), C(1)–C(3) = 1.502(4),
C(3)–C(4) = 1.357(4), C(4)–C(5) = 1.418(4), C(5)–C(6) = 1.193(4);
C(1)–N(1)–C(2) = 110.7(2), C(1)–N(1)–C(7) = 124.3(3), N(1)–C(1)–
C(3) = 106.6(3), N(1)–C(2)–C(4) = 105.8(2), C(4)–C(3)–C(1) =
1
07.5(3)
SCHEME 4 Conversion of ferrapyrrolinone complex into maleimide
The plane of phenyl ring bonded to the nitrogen atom is 49.96°
and 49.88° away from the plane of maleimide ring plane of
compounds 2 and 5, respectively.
It is evident from the crystal structures of all four
ferrapyrrolinone ring‐containing compounds that alkynes
add regiospecifically to form only those isomers illustrated
in Schemes 2 and 3, i.e. ferrocenyl group of activated triple
bond to the β‐carbon of the ferrapyrrolinone ring. This obser-
vation is in agreement with previous reports that, for the
metallapyrrolinone complexes, electronic rather than steric
SCHEME 5 Formation of bisferrole and monoferrole from
substituted butadiyne

JHA ET AL.
5 of 6
pendant under facile conditions. Kinugasa and Agawa have
reported the reaction of diphenylbutadiyne with
carbodimides in the presence of iron pentacarbonyl
at 155–210 °C producing 1,1′,3,3′‐tetraphenyl‐2′,5,5′‐
tris(phenylimido)‐4,4′‐bipyrroline‐2‐one in 14% yield which
further upon acid hydrolysis gives corresponding bipyrroline
4.2 | Crystal structure determination
Suitable X‐ray‐quality crystals of compounds were grown by
slow evaporation of n‐hexane and dichloromethane bilayer at
1
0–15 °C, and X‐ray crystallographic data were collected
with an Oxford Diffraction Xcaliber‐S CCD system equipped
with area detector used for the cell determination and inten-
sity data collection for compounds 2, 3, 4, 5 and 3a. Mono-
chromatic Mo Kα radiation (0.71359 Å) was used for the
measurements. For absorption corrections multi ψ‐scans
were applied. Structures were solved by direct methods
[20]
2,2′,5,5′‐tetrones.
Under our experimental conditions, the
second C☰C is also activated (4) which is certainly a very
rare observation. However, the yield is very low (ca 12%)
and a little susceptible to the amount of iron pentacarbonyl
and phenylisocyanate used.
(
SHELXS) and refined by full‐matrix least‐squares against
2 [23]
Fo using SHELXL‐97 software.
Non‐hydrogen atoms
were refined with anisotropic thermal parameters. All hydro-
gen atoms were geometrically fixed and allowed to refine
using a riding model. Relevant crystallographic data and
details of measurements are given in Table S1.
3
| CONCLUSIONS
We have developed the one‐step photochemical synthesis of
phenyl‐ and ferrocenyl‐substituted ferrapyrrolinone com-
plexes starting with easily available acetylenes and isocya-
nate. In all ferrapyrrolinone complexes, ferrocenyl group
4.3 | Photochemical reaction of
(electron‐donating group) appears at the β‐carbon of the
Ferrocenylacetylene, with PhNCO and [Fe(CO)
added alkyne in ferrapyrrolinone ring. Exclusive formation
of only one type of isomer of ferrapyrrolinone complexes is
controlled electronically rather than sterically. In contrast to
the usual behaviour of substituted butadiyne where one
C☰C reacts while the other remains as a pendant,
diferrocenylbutadiyne shows the activation of both C☰C
]
5
To 70 ml of dry hexane, 105 mg (0.5 mmol) of
ferrocenylacetylene, 0.3 ml of PhNCO (0.5 mmol) and
0
.5 ml of [Fe(CO) ] (2 mmol) were added. The solution
5
was photolysed for 30 min at 0 °C. After the completion of
reaction, reaction mixture was left to cool to room tempera-
ture. It was dried using a rotary evaporator and mixture was
separated on TLC plate in 25% dichloromethane in hexane
solution.
under
photochemical
conditions.
Conversion
of
ferrapyrrolinone complex to useful organic maleimide has
also been achieved.
4
.4 | Photochemical reaction of
Diferrocenylbutadiyne, with PhNCO and [Fe
CO) ]
4
4
| EXPERIMENTAL
.1 | General procedures
(
5
To 70 ml of dry hexane, 122 mg (0.3 mmol) of
diferrocenylbutadiyne, 0.3 ml of PhNCO (0.5 mmol) and
All reactions and manipulations were performed using stan-
dard Schlenk line techniques under an inert atmosphere of
purified nitrogen. Solvents were purified, dried and distilled
under an argon atmosphere prior to use. Photochemical reac-
tions were carried out in a cold double‐walled quartz vessel
having a 125 W immersion‐type mercury lamp manufactured
by Applied Photophysics Ltd. IR spectra for all compounds
were recorded with a Nicolet 380 FT‐IR spectrophotometer
as KBr pellets and NMR spectra were recorded with a Bruker
0
.3 ml of [Fe(CO) ] (1.2 mmol) were added. The solution
5
was photolysed for 40 to 120 min at 0 °C, After the comple-
tion of reaction, reaction mixture was left to cool to room
temperature. It was dried using a rotary evaporator and the
mixture was separated on TLC plate in 25% dichloromethane
in hexane solution.
Avance III 400 spectrometer in CDCl ; carbon atom labelling
3
4
.5 | Photochemical reaction of
Phenylferrocenylbutadiyne, with PhNCO and
Fe(CO) ]
scheme for NMR spectral data interpretation is shown in
Figure S1. Iron pentacarbonyl (97% pure) was purchased from
Fluka. Phenylisocyanate was purchased from Aldrich and
[
5
[
21]
used without further purification. Ferrocenylacetylene,
diferrocenyldiacetylene and ferrocenylphenyldiacetylene
To 70 ml of dry hexane, 155 mg (0.5 mmol) of
phenylferrocenylbutadiyne, 0.3 ml of PhNCO (0.5 mmol)
and 0.3 ml of [Fe(CO) ] (1.2 mmol) were added. The solu-
[22]
were prepared using a reported standard procedure.
TLC
5
plates were purchased from Merck (20 × 20 cm silica
gel 60 F254).
tion was photolysed for 40 to 120 min at 0 °C. After the com-
pletion of reaction, reaction mixture was left to cool to room

6
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JHA ET AL.
temperature. It was dried using a rotary evaporator and the
mixture was separated on TLC plate in 25% dichloromethane
in hexane solution.
[13] P. Mathur, D. K. Rai, R. K. Joshi, B. Jha, S. M. Mobin, Organome-
tallics 2014, 33, 3857.
[14] P. Mathur, R. K. Joshi, D. K. Rai, B. Jha, S. M. Mobin, Dalton
Trans. 2012, 41, 5045.
[15] a) P. Portius, J. Yang, X.‐Z. Sun, D. C. Grills, P. Matousek, A. W.
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ACKNOWLEDGEMENTS
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ment of India. A.R. is grateful to CSIR, Government of
India for research fellowship.
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How to cite this article: Jha BN, Raghuvanshi A,
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route to ferrocenyl‐substituted ferrapyrrolinone
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