Propargyloxy- and allenyloxymethylferrocenes: Synthesis and oligomerization

Article abstract of DOI:10.1016/j.jorganchem.2013.06.025

Propargyloxymethylferrocene has been synthesized by the modified reaction of available N,N-dimethylaminomethylferrocene with propargyl alcohol in the presence of dichloroethane and NaOH, the yield reaching 99.6%. The rapid prototropic isomerization of pro

Full text of DOI:10.1016/j.jorganchem.2013.06.025

Accepted Manuscript
Propargyloxy- and allenyloxymethylferrocenes: synthesis and oligomerization
Ol’ga A. Tarasova, Inna V. Tatarinova, Tamara I. Vakul’skaya, Spartak S. Khutsishvili,
Vladimir I. Smirnov, Lyudmila V. Klyba, Galina F. Prozorova, Al’bina I. Mikhaleva,
Boris A. Trofimov
PII:
S0022-328X(13)00473-7
10.1016/j.jorganchem.2013.06.025
JOM 18098
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 21 January 2013
Revised Date: 14 March 2013
Accepted Date: 21 June 2013
Please cite this article as: O.’g.A. Tarasova, I.V. Tatarinova, T.I. Vakul’skaya, S.S. Khutsishvili,
V.I. Smirnov, L.V. Klyba, G.F. Prozorova, A.’b.I. Mikhaleva, B.A. Trofimov, Propargyloxy- and
allenyloxymethylferrocenes: synthesis and oligomerization, Journal of Organometallic Chemistry (2013),
doi: 10.1016/j.jorganchem.2013.06.025.
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CH2
n
m
NMe2
1. Cl(CH2)2Cl
O
O
O
O
t-BuOK-DMSO
AIBN
Fe
r.t., 4 min
Fe 99.6%
Fe
HC
2.
CCH2OH,
NaOH
80%
m + n = 3-4
88%
Fe
Fe
WCl6
n
O
Fe
83%

*Graphical abstract: synopsis (for review)
Propargyloxy- and allenyloxymethylferrocenes:
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synthesis and oligomerization
Ol'ga A. Tarasova, Inna V. Tatarinova, Tamara I. Vakul’skaya, Spartak S. Khutsishvili, Vladimir I. Smirnov,
Lyudmila V. Klyba, Galina F. Prozorova, Al'bina I. Mikhaleva, Boris A. Trofimov
A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of Russian Academy of Sciences, 1 Favorsky St.,
664033 Irkutsk, Russian Federation

*Highlights (for review)
ACCEPTED MANUSCRIPT
Highlights
An efficient method for the synthesis of propargyloxymethylferrocene in almost quantitative
yield has been elaborated. Previously unknown allenyloxymethylferrocene has been synthesized
in 80% yield. Preliminary cationic and radical oligomerizations of both monomers have been
studied and novel oligomers with the polyene chain and pendant ferrocenyl moieties synthesized
in 83-88% yields. The oligomers exhibit semiconducting and paramagnetic properties and stable
up to 300-340 ºC.

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ACCEPTED MANUSCRIPT
Propargyloxy- and allenyloxymethylferrocenes: synthesis and oligomerization
Ol’ga A. Tarasova, Inna V. Tatarinova, Tamara I. Vakul’skaya, Spartak S. Khutsishvili, Galina F.
Prozorova, Al’bina I. Mikhaleva, Boris A. Trofimov
A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of Russian Academy of Sciences, 1 Favorsky St., 664033
Irkutsk, Russian Federation
A B S T R A C T
Propargyloxymethylferrocene has been synthesized by the modified reaction of available N,N-
dimethylaminomethylferrocene with propargyl alcohol in the presence of dichloroethane and
NaOH, the
yield
reaching 99.6%.
The rapid
prototropic isomerization of
propargyloxymethylferrocene in the superbase system t-BuOK/DMSO (room temperature, 4 min)
leads to previously unknown allenyloxymethylferrocene in 80% yield. Preliminary cationic and
radical polymerization of both monomers have been studied and novel oligomers with the polyene
chain and pendant ferrocenyl moieties containing soluble and insoluble fractions have been
synthesized in 83-88% total yields. All the oligomers exhibit semiconducting and paramagnetic
properties and stable up to 300-340 ºC.
Keywords: propargyloxymethylferrocene, allenyloxymethylferrocene, synthesis, oligomerization, electroconductivity,
paramagnetic properties
1. Introduction
Chemistry of the ferrocene-tailored compounds keeps rapidly developing due to the great
diversity of their applications. The ferrocene derivatives are applied as biosensors [1,2], ligands of
asymmetric synthesis catalysts [3,4], ionic liquids [5], components of the rocket propellants [6],
starting materials for various carbon modifications [7]. They exhibit multi-facet biological activity
including anti-malarial [8], anti-cancer [9-12], anti-microbial [13,14]. They possess electrochromic
[15] and NLO properties [16], and prospective as electro-conductive materials [17].
Now, an ever-growing attention is attracted to ferrocene-containing polymers and oligomers as
promising materials for advanced technologies. In this line, of a special interest are the polyenes
with pendant ferrocenyl moieties. For instance, the polyene obtained from ethynylferrocene in the
presence of rhodium catalysts, is considered as new cathode-active, charge-storage material for
rechargeable batteries [18]. Oligomers and copolymers of the same monomer synthesized in the
presence of molybdenum catalysts show NLO properties [19]. Recently, we have synthesized
 Corresponding author. Fax: +7 3952 419346.
E-mail address: boris_trofimov@irioch.irk.ru (B.A. Trofimov).

2
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similar polyenes, having semi-conducting and paramagnetic features, oligomerization of
phenylferrocenylacetylene in the presence of WCl6 [20].
Here we report a new synthetic approach from ferrocene to propargyloxymethylferrocene (1)
and allenyloxymethylferrocene (2) and their oligomers, reactive building blocks, monomers and
macromonomers.
Ferrocene (1) has been recently synthesized (in 50% yield) by the reaction of
ferrocenylmethanol with propargyl bromide in DMSO in the presence of NaOH [21]. The starting
ferrocenylmethanol was prepared by reduction of ferocenylcarbaldehyde [22]. Ferrocene (1) has
been employed for the synthesis of supramolecular structures [21], 4-(ferrocenylmethoxymethyl)-1-
(1,2,3-triazolyl)benzylacetate [23] and ferrocene-glycine conjugate [24], the latter being applied as
electrochemical receptor for selective detection of Hg+2 in water.
2. Results and discussion
The disadvantage of the known method for the preparation of propargyloxymethylferrocene
(1) is application of expensive t-BuLi at the stage of ferrocene deprotonation.
Here for the synthesis of ferrocene (1) we have modified the synthesis of
alkoxymethylferrocenes via quaternary ammonium salts of N,N-dimethylaminomethylferrocene (3)
[25-27]. This method was previously used for the preparation of alkyl and allyl ethers of
ferrocenylmethanol [25,26]. However, its suitability for the preparation of propargyl ethers remains
obscure. Our modification of the synthesis of ferrocene (1) comprises the reaction between N,N-
dimethylaminomethylferrocene (4) and propargyl alcohol in the presence of dichloroethane (90-96
ºC, 1.5 h) followed by the treatment with NaOH (54-103 ºC, 2 h). The yield of ferrocene (1) is
almost quantitative (99.6% based on the aminomethylferrocene 4 consumed or 72% based on the
ferrocene 4 taken), Scheme 1. Unreacted ferrocene 4 is easily isolated (as the salt) from the reaction
mixture upon its acidification with 2% aqueous HCl.
Me
N
Me
MeCOOH
Me
Me
Fe
Fe
(CH2O)n
+
N
N
+
refluxing, 5 h
Me
Me
51%
4

3
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Me
N
O
1. ClCH2CH2Cl
Me
90-96 oC, 1.5 h
2. HC CCH2OH, NaOH
54-103 oC, 2 h
Fe
Fe
99.6%
4
1
Scheme 1. Synthesis of propargyloxymethylferrocene from ferrocene.
Apparently, the quaternary ammonium salt (3) undergoes the nucleophilic substitution by
propargyloxy anion at the FcCH2 carbon to release (2-chloroethyl)dimethylamine hydrochloride,
which further decomposes by NaOH (Scheme 2).
Me
Me
N
O
OH
/ NaOH
Cl
Cl
+
Me2NCH2CH2Cl + NaCl
Fe
Fe
1
3
Scheme 2. Decomposition of quaternary ammonium salt (3) under the action of propargyl
alcohol and NaOH.
The obvious advantages of the method developed (except for the quantitative yield of the
target product) are its one-pot implementation, avoiding use of expensive t-BuLi and inert
atmosphere which require for the synthesis of ferrocene carbaldehyde, an intermediate in the
alternative method [22]. The starting N,N-dimethylaminomethylferrocene (4) is readily available by
aminomethylation of ferrocene with N,N,N’,N’-tetramethyldiaminomethane and paraform
according to [28].
Previously unknown allenyloxymethylferrocene (2) has been synthesized by the instant
prototropic isomerization of ferrocene 1 in the superbase system t-BuOK-DMSO (room
temperature, 4 min), the yield being 80% and the conversion of ferrocene 1 reaching 96% (Scheme
3).

4
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.
O
O
t-BuOK-DMSO
r.t., 4 min
Fe
Fe
80%
1
2
Scheme 3. Prototropic isomerization of ferrocene 1 to allenyloxymethylferrocene (2).
Thus, due to the methods elaborated, ferrocenes 1 and 2 are now becoming readily available
ferrocene synthons and monomers for their further large-scale explorations, first of all,
oligomerization.
Previously, we have carried out the cationic oligomerization of phenylferrocenylacetylene in the
presence of WCl6 (4.6%) [20]. Consequently, we have employed this catalyst for cationic
oligomerization of ferrocene
1
to afford the expected polyene
5
with pendant
ferrocenylmethyloxymethyl moieties (Scheme 4).
n
O
O
WCl6, 4.6%
60-100 oC, 0.08-20 h
Fe
Fe
1
5
Scheme 4. Cationic oligomerization of propargyloxymethylferrocene.
Under the conditions shown in Table 1, oligomers 5 have been isolated as soluble (benzene,
chlorobenzene and chloroform) and insoluble fractions in a total yield up to 83%, 5а,c,e and 5b,d,f,
respectively. When oligomerization is performed in benzene (60 ºС), the yields of the soluble and
insoluble fractions are 55% and 21%, correspondingly. Under the solvent-less conditions (100 ºС)
the yield of the soluble fraction decreases to 33%, while the yield of insoluble increases to 50%
(Table 1).
Table 1

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Conditions of monomers 1, 2 oligomerization
Monomer Catalyst or initiator (wt %)а
Т, оС
Time, h
Oligomer Yield, %
33b
50c
55b
21c
20b
11c
5a
WCl6, 4.6
WCl6, 4.6
WCl6, 4.6
100
60d
60d
0.08
20
2
1
1
1
5b
5c
5d
5e
5f
LiBF4, 2.0
AIBN, 3.0
AIBN, 2.0
AIBN, 3.0
AIBN, 2.0
60
80
80
60
60
24
24
24
69
24
10b
88b
79b
81b
2
6
2
7a
2
7b
2
7c
44b
2
7d
а Relative to monomer.
b Yield of the soluble fraction.
c Yield of the insoluble fraction.
d Polymerization in benzene (monomer:benzene = 1:3).
The IR spectra confirm that polyenes 5a-f consist of the polyene chain with pendant
ferrocenylmethyloxymethyl substituents. The spectra lack the absorption bands at 3222 (HC) and
2119 cm-1 (C≡C) which are present in monomer 1. Absorption bands of the ferrocene nuclei (1730-
1685 cm-1), С–О–С (1037-1022 cm-1) and OСН2 (2886-2833 cm-1) groups remain in the spectra and
absorption band of the polyene chain appears at 1640-1630 cm-1. As typical for oligomers, all the
absorption bands are broaden.
1
The Н NMR spectrum of oligomers 5а,c,e shows broad signals of the vinyl protons at 5.69-
5.46 ppm, broad signals of ferrocene skeleton protons at 4.35-3.90 ppm, while a signal of the OCH2
group protons (4.11-4.15 ppm) is observed in a region of ferrocene protons. Also, signals of the C–
CH2 group protons appear (3.31-3.39 ppm), and signals of the –CCH fragment are absent (in the
monomer the signal of this fragment is at 2.43 ppm).
The cationic oligomerization of allenyloxymethylferrocene (2) has been carried out in the
presence of catalytic system LiBF4–dimethoxyethane (DME), especially efficient in the
polymerization of vinyl ethers [29], the soluble oligomer 6 in 10% yield has been obtained (Table 1,
Scheme 5).

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CH2
.
LiBF4DME, 2%
n
60 oC, 24 h
O
O
Fe
Fe
2
6
Scheme 5. Cationic oligomerization of allenyloxymethylferrocene.
1
According to the IR and Н NMR spectra, the oligomerization proceeds across the double bond
adjustment to the oxygen atom to form the oligomer containing exo-methylene group in each
oligomer unit that is in agreement with the literature data on polymerization of alkoxyallenes [30,
31]. In the IR spectrum of sample 6, absorption bands assigned to the CH2=C group are observed at
1642 cm-1, and the absorption bands of the ferrocene skeleton (1715-1680 cm-1) and the С–О–С
1
(1040-1024) and OСН2 (2886-2833) groups remain. In the Н NMR spectrum, one signals of the
vinyl group protons is present at 4.93-4.98 ppm (СН2=С), protons of the polymer chain –CH appear
at 2.58-2.44 ppm, signals of the ferrocene fragment and the OCH2 group are observed at 4.32-4.21
and 4.40-4.34 ppm, respectively.
Oligomerization of allenyloxymethylferrocene (2) has also been carried out under radical
conditions in the presence of azobisisobutiric acid dinitrile (AIBN) (Scheme 6).
CH2
.
AIBN, 2-3%
60-80 oC, 24-69 h
n
m
O
O
O
Fe
Fe
Fe
2
n + m = 8-9
7
Scheme 6. Radical oligomerization of allenyloxymethylferrocene.
Conditions of monomer 2 oligomerization and the oligomers yield are given in Table 1.

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The experiments have shown that allenyloxymethylferrocene (2) is more reactive under the
radical oligomerization as compared to the cationic ones. The soluble oligomers have been obtained
in up to 88% yields (Table 1). The highest yield is achieved at 80 ºС in the presence of 3.0% AIBN.
The decrease of temperature and AIBN concentration leads to the reduction of the oligomer yield.
Molecular weight of oligomer 7а is 2000 that corresponds to 8-9 elementary units.
1
The structure of oligomers 7a-d has been proved by IR and Н NMR spectroscopy. In the IR
spectra of compounds 7a-d, absorption bands of the C=C=C bond are absent (in the monomer this
band is observed at 1950 cm-1). The bands of other groups and bonds were significantly broadened.
The absorption bands of the ferrocene skeleton are present in the region 1730-1685 cm-1. The
absorption bands of the C=CH–O group appear at 1670-1660 cm-1. Also, the absorption bands
1
attributed to the CH2=C exo-methylene fragments are shown at 1645-1636 cm-1. The Н NMR
spectrum contains broaden signals characteristic of the vinyl group protons at δ 5.31-5.09 ppm
(СН2=С) and δ 6.19-5.94 ppm (СН=С), the polymer chain protons –CH2 (4.02-3.88 ppm) and –CH
(2.62-2.46 ppm), the ferrocene moiety (4.28-4.11 ppm) and signals of the OCH2 group at 4.42-4.38
ppm.
From the spectral data follows that under radical polymerization of allenyloxymethylferrocene
(2), macromolecules 7a-d are formed at the 1,2- and 2,3-positions of the allenyl group, as it is
observed for alkoxyallenes [32-33], i.e. they have two types of structural blocks containing no
polyene chains (Scheme 5).
Electroconducting and paramagnetic properties of oligomers 5a,b and 7a have been studied and
their thermal behavior has been evaluated.
As expected, the oligomers exhibit properties of organic semiconductors (σ = 2.5×10-10
-
8.8×10-10 S/cm). When doped with iodine, their electroconductivity increases by 4-5 orders (σ =
4.3×10-6 - 1.7×10-5 S/cm) (Table 2).
Table 2
Electroconductivity and paramagnetic properties of the oligomers
Intensity of
Iodine
Compounds content σ, S/cm
the main ESR
signal, rel.
un.a
Additional peaks in
ESR spectra, g-factor
ΔН, G
g-factor
(%)
No
No
-
3.1
10.0
7.6
320
220
250
700
2.24
2.01
2.01
2.21
4.43; 3.26; 2.03; 1.96
4.39; 2.97; 2.22
4.39; 2.97
1
5a
8.8×10-10
6.4×10-10
1.7×10-5
No
5b
68.79
19.0
4.30; 2.50; 2.0052b
5b-I

8
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No
No
-
2.4
1.0
6.7
305
2.20
2.19
3.43; 1.97; 1.85
3.01; 1.99
2
2.5×10-10
4.3×10-6
630
7a
520
170
2.17
2.03
47.48
4.30; 2.50; 2.0052b
7a-I
a Relative to minimum, signal of compound 7а.
b Narrow (ΔН ≈ 10 G) symmetric singlet, g-factor was measured in the range of 100 G.
The detail study of the ESR spectra of the starting compounds 1, 2 and the oligomers
synthesized (Table 2) have shown that all the solid compounds are paramagnetic at room
temperature. The ESR spectra of the starting compounds 1 and 2 contain central broad bands of
almost the same intensity with ΔH ~300 G. The bands are strongly low-field shifted (towards the
increase of g-factor in comparison with this value for free electron). In addition, in the ESR spectra,
some low-intensive absorption bands are present in the region of low and high fields of the both
compounds. Also, in the spectra, the peaks with g-factors 4.43 and 3.43 for compounds 1 and 2
respectively, are observed (Table 2). The values of the g-factors allows one to conclude that iron in
the compounds obtained is three-valent and mainly in low-spin state [34]. When sample 1 and 2 are
dissolved in chloroform, all the ESR signals disappear.
The ESR spectra of soluble 5a and insoluble 5b fractions of poly(propargyloxymethylferrocene)
considerably differ from those of the starting compound 1 and between each other (Table 2). But
the signals character and g-factor values also correspond to three-valent iron in low-spin state.
The ESR spectrum of oligomer 7а consists of broad (more than 600 G) asymmetric line with g-
factor of approximately 2.2. In comparison with the starting compound 2, central signal of the
polymer becomes broader and is high-field shifted. This indicates the alteration of asymmetry of
paramagnetic centers surrounding that leads to decrease of spin-orbitals contribution and shortening
the relaxation time. A narrow signal with g-factor 1.99, which is often present in the ESR spectra of
three-valent iron in low-spin state, appears.
The dopping of samples 5b and 7a with iodine gives almost the identical ESR spectra. Integral
intensity of the spectra increases for oligomer 5b-I by 2.5 times, and for compound 7a-I – by the
order. In the spectra of the dopped samples, all weak low-field absorption bands disappear and
intensities of low-field bands sharply decrease. The main intensive band is split and in the region g
= 2.0052 of sample 5b-I, a narrow band of 10 G appears. In the spectrum of oligomer 7a-I, this
band is almost indiscernible, but it has been recorded in narrow range of field screening. This signal
can be assigned to free radicals (polarons), formed during the dopping.
Since ferrocene itself is diamagnetic, the paramagnetism of the monomers and their oligomers
can be rationalized by the stacking effect, both in the monomer crystals and the oligomer solids,
transmitted through the ferrocene units with a participation of the multiple bonds.

9
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The investigation of thermooxidative destruction of polymers 5a, 5b have revealed that they are
stable to 330-340 ºС. Upon further heating up to 460-480 ºС, the weight loss is 50%. The DTA
curves show one exothermic peak at 380 ºС and 400 ºС for 5b, 5a respectively (Т = 30 и 36 ºС).
Total decomposition of the polymers is observed at 590-610 ºС.
Oligomer 7a is slightly less stable than 5a and 5b. Its decomposition begins at 300 ºС. Further
heating up to 420 ºС leads to 50% weight loss. One exothermic peak at 435 ºС (Т = 86 ºС) is
detected on the DTA curve. Total decomposition of the polymers occurs at 510 ºС.
3. Conclusion
An efficient method for the synthesis of propargyloxymethylferrocene in almost quantitative
yield has been elaborated. The synthesis is based on the modified reaction of available N,N-
dimethylaminomethylferrocene with propargyl alcohols in the presence dichloroethane and NaOH.
Previously unknown allenyloxymethylferrocene has been synthesized in 80% yield by rapid
prototropic isomerization of propargyloxymethylferrocene in the superbase system t-BuOK–DMSO
(room temperature, 4 min). Propargyloxymethylferrocene undergoes cationic polymerization in the
presence of WCl6 to afford polyenes with pendant ferrocenyl groups, consisting of soluble (20-
55%) and insoluble (11-50%) fractions, in up to 83% total yield. Allenyloxymethylferrocene
oligomerizes preferably radically (initiator AIBN) to soluble oligomers with exo-methylenic groups
in up to 88% yield. All the oligomers possess semiconducting and paramagnetic properties and
stable up to 300-340 ºC. The monomers and oligomers synthesized represent prospective building
blocks and components for the design of advanced materials.
4. Experimental section
4.1. General remarks
IR spectra of propargyloxymethylferrocene (1), allenyloxymethylferrocene (2) and oligomers 5-
7 were registered in the region 400-4000 cm-1 with a FT IR Spectrometer Vertex-70 instrument as
KBr pellets. NMR spectra were recorded at room temperature on a Bruker DPX 400 (400.13 MHz
1
for H and 100.6 MHz for 13C) using СDCl3 solvent and HMDS as the internal standard. The
microanalyses were performed on a Flash EA 1112 Series elemental analyzer. The electrical
conductivity of polymers 5а,b and 7a was measured with an E6-13A teraohmmeter. The studied
samples were prepared as pellets by molding under a pressure of 700 kg cm-2. The oligomers were
doped with iodine using diffusion technique from gas phase for 24 h. The ESR spectra were
measured with an ELEXSYS E580 Bruker spectrometer in CW mode (frequency 9.7 GHz, high

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frequency modulation 100 KHz, amplitude modulation 10 G) at room temperature. The relative
concentration of paramagnetic centers was calculated as double integral per gram and standardized
per unit. The thermogravimetric analysis (TGA) of oligomers 5а-b, 7a was performed on a Q-
1500D derivatograph (MOM, Hungary), maximal temperature 700 ºС, at heating rate of 5 ºC min-1;
the sensitivity for DTA was 1/10. To evaluate the molecular weight of oligomers 7а size exclusion
chromatography (SEC) in THF (0.2% solution) was conducted at an elution rate of 1.1 mL min-1
using Waters gel columns: 250, 500, and 1000Å at 25 ºС.
N,N,N’,N’-Tetramethyldiaminomethane and N,N-dimethylaminomethylferrocene were
synthesized by literature procedures [28].
Solvents (benzene, n-hexane) were purified according to the literature protocols [35]. AIBN was
recrystallized twice from ethanol (m.p. 102 ºС).
4.2. Synthesis
4.2.1. Propargyloxymethylferrocene (1)
A mixture of FcCH2NMe2 (14.72 g, 0.06 mol) (4), propargylic alcohol (72.23 g, 1.29 mol) and
dichloroethane (23.8 g, 0.24 mol) was heated at 90-96 С for 1 h 30 min and cooled to 54 ºС. Then
powdered NaOH (9.6 g, 0.24 mol) was added in one portion and the mixture was heated at 83-103
С for 2 h. The unreacted alcohol (43 g) was distilled. Water (100 ml) was added to the residue and
the products were extracted with ether (5 х 50 ml). The black extracts were washed with water (3 х
40 ml), 2% HCl (3 х 30 ml), and again with water (3 х 30 ml) and dried over K2CO3. After removal
of ether under slight vacuum and vacuumizing the residue (1 Hg mm, ~50 С, 20 min), 17.25 g of
orange crystalline product was obtained. From the latter pure propargyloxymethylferrocene (1) (11
g, 72%) was isolated by chromatography with ether over small layer (3 cm) of Al2O3 (neutral) and
repeated recrystallization from ether at –15 С. Acidic aqueous solution of the amine 4
hydrochloride was neutralized with 20% solution of KOH until strongly alkaline reaction and
extracted with ether (3 х 20 ml). The extracts were washed with water, dried over K2CO3 and after
removal of the solvent 4.89 g of residue was obtained. From the latter, 4.15 g of N,N-
dimethylaminomethylferrocene (4) was isolated, b.p. 125 ºC<1 Hg mm.
The yield of
propargyloxymethylferrocene (1) calculated by the consumed N,N-dimethylaminomethylferrocene
was 99.6%, m.p. 95-96 ºС (amber plates from Et2O). IR (KBr, cm-1): 3223 s ( C–H), 3103 w,
3067 w, 2977 w, 2923 w, 2899 w, 2862 w, 2119 w (CC), 1780-1600 (w, ferrocene skeleton),
1456 m, 1444 w, 1410 w, 1397 w, 1374 m, 1353 m, 1269 m, 1213 w, 1103 m, 1066 s, 1038 m, 994
1
m, 955 m, 926 w, 908 m, 877 m, 831 m, 808 m, 748 m, 704 m, 549 w, 494 m, 477 m. H NMR
3
3
(CDCl3):  4.37 (s, 2H, CH2O), 4.24 (t, 2H, Jαβ = 1.83 Hz, H), 4.15 (t, 2H, Jβα = 1.83 Hz, H),
4
4
4.13 (s, 5H, C5H5), 4.10 (d, 2H, JCH2-CCH = 2.34 Hz, CH2–CCH), 2.43 (t, 1H, JCH2-CCH = 2.34

11
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13
Hz, HCC–CH2). C NMR (CDCl3):  82.21 (Ci), 79.88 (–C), 74.31 (HC), 69.47 (C), 68.58
(C), 68.41 (C5H5), 67.56 (OCH2), 56.39 (CH2–CCH). Anal. Calc. for C14H14FeO (254.10): C,
66.17; H, 5.55; Fe, 21.98. Found: C, 66.20; H, 5.57; Fe, 21.92.
4.2.2. Allenylyloxymethylferrocene (2)
To a solution of t-BuOK (2.8 g, 25.0 mmol) in dry DMSO (90 ml, water content < 0.2%), was
added propargyloxymethylferrocene (6.0 g, 23.6 mmol) (1). The reaction mixture was stirred for 4
min at room temperature (23 ºС), then diluted with cold water (~200 ml), extracted with ether (4 х
50 ml). The combined ether solution was washed with water to remove DMSO and dried over
MgSO4. After removal of ether under slight vacuum and vacuumizing the residue (1 Hg mm, 20
min), the product was purified by column chromatography on Al2O3 (eluent – petroleum ether–
Et2O, 15:1) to recover 0.24 g of propargyloxymethylferrocene (conversion 96%) and to give 4.8 g
of allenyloxymethylferrocene (80% yield), m.p. 46-48 ºС (yellow crystals). IR (KBr, cm-1): 3089 w,
3033 w, 2983 w, 2927 w, 2892 w, 2850 w, 1950 m (C=C=C), 1729-1600 (w, ferrocene skeleton),
1476 w, 1461 m, 1408 w, 1397 w, 1381 m, 1359 w, 1248 m, 1243 m, 1188 s, 1104 m, 1030 s, 997
m, 967 w, 913 m, 893 m, 866 w, 850 w, 839 w, 827 m, 813 m, 781 w, 704 m, 652 w, 507 m, 496 m,
483 m. 1H NMR (CDCl3):  6.73 (t, 1H, 4JCH=C=CH2 = 5.87 Hz, CH=C=CH2), 5.48 (d, 2H, 4JCH=C=CH2
3
3
= 5.87 Hz, CH=C=CH2), 4.35 (s, 2H, CH2O), 4.24 (t, 2H, Jαβ = 1.71 Hz, Hα), 4.15 (t, 2H, Jβα =
1.71 Hz, Hβ), 4.13 (s, 5H, C5H5). 13C NMR (CDCl3):  201.28 (CH=C=CH2), 121.37 (CH=C=CH2),
90.77 (CH=C=CH2), 82.49 (Ci), 69.23 (C), 68.56 (C), 68.45 (C5H5), 67.01 (OCH2). Anal. Calc.
for C14H14FeO (254.10): C, 66.17; H, 5.55; Fe, 21.98. Found: C, 65.98; H, 5.52; Fe, 21.97.
4.3. Oligomerization
4.3.1. Propargyloxymethylferrocene (1)
Propargyloxymethylferrocene (3 g, 11.81 mmol) (1) and WCl6 (0.14 g, 0.35 mmol) were placed
in ampoule blown with argon. The ampoule was sealed, heated in thermostat at 100 ºС for 5 min,
cooled and opened. The reaction mixture was dissolved in benzene (15 ml) and insoluble fraction
was separated from soluble one by filtration. The insoluble fraction was washed with benzene. The
soluble fraction was precipitated in n-hexane (50 ml) and washed with the precipitant (3×50 ml).
Both fractions were dried in vacuum (1 Hg mm) to the constant weight to give 0.98 g (33%) of
soluble oligomer 5а and 1.50 g (50%) of insoluble oligomer 5b. The soluble fraction 5a is a brown
powder (m.p. 196-198 ºС), soluble in benzene, chlorobenzene, chloroform. Anal. Calc. for
C14H14FeO (254.10): C, 66.17; H, 5.55; Fe, 21.98. Found: C, 66.04; H, 5.70, Fe 21.88. Insoluble
fraction 5b is a black powder unmelted up to 350 С. Anal. Calc. for C14H14FeO (254.10): C, 66.17;
H, 5.55; Fe, 21.98. Found, %: C, 65.94; H, 5.78, Fe 21.76.

12
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4.3.2. Propargyloxymethylferrocene (1) (in benzene)
Propargyloxymethylferrocene (3 g, 11.81 mmol) (1) and WCl6 (0.14 g, 0.35 mmol) dissolved in
benzene (10 ml) were placed in ampoule filled with argon. The ampoule was sealed and heated in
thermostat at 60 ºС for 20 h. After the reaction completion, the ampoule cooled and opened and
insoluble fraction was separated from soluble one by filtration. The insoluble fraction was washed
with benzene. The soluble fraction was precipitated in n-hexane (50 ml) and washed with the
precipitant (3×50 ml). Both fractions were dried in vacuum (1 Hg mm) to the constant weight to
give 1.64 g (55%) of soluble oligomer 5с and 0.64 g (21%) of insoluble oligomer 5d. The soluble
fraction 5c is a brown powder (m.p. 193-196 ºС), soluble in benzene, chlorobenzene, chloroform.
Anal. Calc. for C14H14FeO (254.10): C, 66.17; H, 5.55; Fe, 21.98. Found, %: C, 66.08; H, 5.69, Fe
21.78. Insoluble fraction 5d is a black powder unmelted up to 350 С. Anal. Calc. for C14H14FeO
(254.10): C, 66.17; H, 5.55; Fe, 21.98. Found, %: C, 66.02; H, 5.71, Fe 21.82.
4.3.3. Allenyloxymethylferrocene (2) (LiBF4–DME)
Catalytic complex LiBF4–DME was prepared by the dissolution of the above salt (0.35 g) in
dimethoxyethane (1.0 g).
To allenylnyloxymethylferrocene (2.0 g, 7.87 mmol) (2) was added 0.15 g of catalytic complex
LiBF4–DME (2 wt % calculated by LiBF4) on stirring in argon flow. The polymerization was
carried out in a sealed ampoule at 60 ºC for 24 h. The ampoule was cooled and opened, the catalyst
was neutralized by gaseous NH3, and the reaction mixture was filtered. The oligomer was dissolved
in benzene (5 ml), precipitated to n-hexane (50 ml), filtered off, washed with n-hexane (3×20 ml)
and dried in vacuum (1 Hg mm) to the constant weight to give 0.2 g (10% yield, m.p. 94-97 ºС) of
oligomer 6. Anal. Calc. for C14H14FeO (254.10): C, 66.17; H, 5.55; Fe, 21.98. Found, %: C, 66.21;
H, 5.60, Fe 21.78.
4.3.4. Allenyloxymethylferrocene (2) (AIBN)
Allenyloxymethylferrocene (4.0 g, 15.74 mmol) (2) and AIBN (0.08 g, 0.49 mmol) were
placed into an ampoule filled with argon. The ampoule was sealed and heated in thermostat at 80 ºС
for 24 h, then cooled and opened. The polymeric product was recovered and purified by re-
precipitation from benzene into hexane, washed with hexane and dried to constant weight to give
3.54 g of poly(allenyloxymethylferrocene) 7a (88% yield, m.p. 98-100 ºС). Anal. Calc. for
C14H14FeO (254.10): C, 66.17; H, 5.55; Fe, 21.98. Found, %: C, 66.14; H, 5.61, Fe 21.70.
Acknowledgement

13
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This work was supported by the President of the Russian Federation (program for the support of
leading scientific schools, grant NSh-1550.2012.3).
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*Response to Reviewers
ACCEPTED MANUSCRIPT
Dear Professor Herrmann,
We are submitting herewith the manuscript entitled “Propargyloxy- and
allenyloxymethylferrocenes: synthesis and oligomerization” by Olga A. Tarasova et al. revised
according to the referess’ critics and suggestions.
First of all, please thank both the referees on our behalf for the fair and genuine work
with our manuscript and very useful remarks which we have addressed in the revised paper.
The following alterations have been made in the manuscript.
Referee 2 wrote: “It is claimed page 5 that the mixture Li BF4-dimethoxyethane is a
cationically polymerizing system. This is rather doubtful because this system is lacking of a
powerful electron deficient site. Whatsoever, oligomerization of allenyloxymethylferrocene was
observed by authors”.
The following paragraphs have been included in the text:
As discovered a while ago [29, 30], the complexes of LiBF4 with dimethoxyethane and
some other ethers of ethylene- and polyethylene glycol are latent cationic catalysts which
effectively catalyze the cationic polymerization of vinyl ethers.
Mechanism of catalysis by these systems involves thermal dissociation of LiBF4 to
release minor concentration of BF3, a well-known catalyst for cationic polymerization [32, 33]:
LiBF4
BF3
+
LiF
At ambient temperature this dissociation is negligible, while upon heating it starts
producing BF3 in amounts enough for polymerization.
Dimethoxyethane transforms the salt LiBF4 to the complex of the separated ion pair type
in which the above dissociation is facilitated:
Me
Me
Me
Me
Me
O
O
O
O
O
O
O
O
O
O

Li+
BF4
Li+
F-
-
+
F3B
O
O
Me
Me
Me
Me
Me
Me
Me
Referee 2 wrote: “Indeed, oligomerization described page 6 can probably better be
assigned to the experimental conditions (60°C, 24 h) inducing a slow radical induced thermal
oligomerization”.
We have checked this suggestion and the following sentence has been included into the
text:
The special experiment has confirmed that thermal oligomerization of monomer 2 at
60°C for 24 h was much slower (the yield of the oligomer did not exceed 3%).
Referee 2 wrote: “About average number molar masses, authors must indicate what were
the standards used in the SEC determinations, because the hydrodynamic volumes of polystyrene
and of polyallenyoxymethylferrocene of the same molar mass must be very different, and the
value given to the polymerization degree could be subject to large overestimation”.
Indeed, according to the mass spectrometry data (Bruker Ultraflextreme TOF/TOF
(Bruker Daltonics GmbH)), oligomer 7a consists of molecules with molecular masses 762 and
1016 that corresponds to trimer and tetramer, probable of cyclic structure. From the spectral data
(see below) follows that the oligomer may be represented by combination of two different
structures:

ACCEPTED MANUSCRIPT
CH2
.
AIBN, 2-3%
n
m
60-80 oC, 24-69 h
O
O
O
Fe
Fe
Fe
2
n + m = 3-4
7
Therefore, the molecular mass data based on GPC given in the first version of the
manuscript are excluded from the text as actually overestimated as the referee suggested.
Referee 2 wrote: “Authors should give 13C NMR spectrum of the soluble fraction and
compare with the spectrum of the monomer”.
In the Results and Discussion, the data of 13C NMR for synthesized oligomers have been
added (pages 5,7,9). Also, original spectrum information concerning these spectrum have been
give in Supporting information as a separate file.
Now, we hope that after all the above amendments the manuscript has been improved to the state
suitable for publication.
Best regards,
Boris Trofimov