Reactions of lithiated 2,5-dimethylazaferrocene with selected electrophiles

Article abstract of DOI:10.1016/j.jorganchem.2004.09.083

Lithiation of 2,5-dimethylazaferrocene 1 with sec-BuLi/TMEDA in THF at -78°C proceeds (as shown by quenching with D₂O) to comparable extent on the methyl groups and the Cp ring. However, the outcome of the reaction of the lithiated 1 with an electrophile depends on the nature of this electrophile. In the reaction with 4-methoxybenzaldehyde only the product originated from the lateral lithiation is formed, whereas the reaction with 4-methoxyacetophenone and 4,4′-dimethoxybenzophenone afforded mixtures of the products resulting from lateral and ring-lithiation. Similar results were also obtained in the reaction of lithiated 1 with chlorodiphenylphosphine and diphenyl diselenide. On the other hand, the exclusive formation of the Cp-substituted product was observed in the reaction of lithiated 1 with N,N-dimethylformamide. The structures of selected products (oily compounds were transformed into the corresponding crystalline W(CO)₅-complexes) were confirmed by X-ray diffraction. The presented reactions open a novel entry to specifically substituted azaferrocenes (especially those containing heteroatom substituents) with potential applications as ligands for the homogenous catalysis.

Full text of DOI:10.1016/j.jorganchem.2004.09.083

Journal of Organometallic Chemistry 690 (2005) 764–772
www.elsevier.com/locate/jorganchem
Reactions of lithiated 2,5-dimethylazaferrocene with selected
electrophiles
a
a,
b
Konrad Kowalski , Janusz Zakrzewski *, Lucjan Jerzykiewicz
a
´ ´
´ ´
Department of Organic Chemistry, Institute of Chemistry, University of Łodz, Narutowicza 68, 90-136 Łodz, Poland
b
Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland
Received 20 May 2004; accepted 3 September 2004
Abstract
Lithiation of 2,5-dimethylazaferrocene 1 with sec-BuLi/TMEDA in THF at ꢀ78 ꢀC proceeds (as shown by quenching with D2O)
to comparable extent on the methyl groups and the Cp ring. However, the outcome of the reaction of the lithiated 1 with an electr-
ophile depends on the nature of this electrophile. In the reaction with 4-methoxybenzaldehyde only the product originated from the
lateral lithiation is formed, whereas the reaction with 4-methoxyacetophenone and 4,40-dimethoxybenzophenone afforded mixtures
of the products resulting from lateral and ring-lithiation. Similar results were also obtained in the reaction of lithiated 1 with chlo-
rodiphenylphosphine and diphenyl diselenide. On the other hand, the exclusive formation of the Cp-substituted product was
observed in the reaction of lithiated 1 with N,N-dimethylformamide. The structures of selected products (oily compounds were
transformed into the corresponding crystalline W(CO)5-complexes) were confirmed by X-ray diffraction. The presented reactions
open a novel entry to specifically substituted azaferrocenes (especially those containing heteroatom substituents) with potential
applications as ligands for the homogenous catalysis.
ꢁ 2004 Elsevier B.V. All rights reserved.
Keywords: Azaferrocene; Lithiation; Selectivity; X-ray diffraction
1. Introduction
nitrogen atom, hampering electrophilic substitution
reactions [1,7]. Up to now the most promising synthetic
strategy for introduction to azaferrocene of desired car-
bon chains and/or functional groups is based on its lith-
iation. It has been found that azaferrocene is lithiated by
n-BuLi to comparable extent on the Cp ring and at the
a-position of the pyrrolyl ring [8]. Moreover, reactions
of lithiated azaferrocene with electrophiles show unex-
pected (and yet inexplicable) selectivities, giving
(depending on the nature of the electrophile) either
Cp- or pyrrolyl-substituted products [9,10]. In the case
of 10,20,30,40,50-pentamethylazaferrocene the only lithia-
tion site is the a position of the pyrrolyl ligand and a
method of generation of enantiomerically pure planary
chiral 2-lithio derivatives of this metallocene has re-
cently been elaborated [11,12]. Another interesting prob-
lem is the possibility to achieve lateral lithiation of the
alkyl groups in 2-position. It has been reported that
Synthesized forty years ago [1,2], the simplest hetero-
ferrocene, azaferrocene, has recently attracted attention
as the backbone of planar chiral nucleophilic catalysts
[3], ligands for asymmetric catalysis [4] and a redox ac-
tive nitrogen ligand enabling novel photoinduced redox
processes of metalloporphyrins and metallophthalocya-
nines [5]. It also undergoes interesting photochemical
transformations [6]. Unfortunately, in contrast to the
very rich synthetic chemistry of its carbocyclic counter-
part, ferrocene, chemistry of azaferrocene is still under-
developed. This is mainly due to the intrinsic instability
of azaferrocene and to the presence of the nucleophilic
*
Corresponding author. Tel.: +4842 678 4731; fax: +4842 678 6583.
E-mail address: janzak@uni.lodz.pl (J. Zakrzewski).
0022-328X/$ - see front matter ꢁ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.09.083

K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
765
10,2,20,30,40,5,50-heptamethylazaferrocene
undergoes
In contrast to the above reaction, treatment of lithi-
ated 1 with 4-methoxyacetophenone afforded a mixture
of products originating from both ring- and laterally
lithiated 1 (3 and 4, respectively). These products were
isolated by column chromatography in 24% and 13%
yield along with recovered 1 (35%). Their structures
were confirmed by spectroscopic methods and elemental
analyses. The 1H NMR spectrum of 3 exhibits four sep-
arate signals of protons of the C5H4 ring (due to the
presence of the stereogenic center in the lateral chain
one can expect two pairs of diastereotopic protons in
this ring), two signals of b-pyrrolyl protons as well as
two three-proton signals of the diastereotopic methyl
selective lithiation at the methyl group in the position
2 [13]. In the presence of chiral ligands an enantioselec-
tive lateral lithiation was accomplished.
We have previously reported [14] that reaction of 2,5-
dimethylazaferrocene 1 with sec-BuLi and TMEDA in
THF at ꢀ78 ꢀC followed by quenching with D2O fur-
nishes starting metallocene having the deuterium label
in the Cp ring (54%), methyl groups (38%) and in the
b-positions of the pyrrolyl ligand (8%). However, inter-
estingly, the reaction of lithiated metallocene with ben-
zyl chloride or 4-methoxybenzaldehyde afforded
exclusively products resulting from the lateral lithiation.
Herein we report an extension of our preliminary
study on a broader range of carbon- and hetero-electro-
philes. We found that depending on the nature of the
electrophile reacting with lithiated 2,5-dimethylazaferro-
cene it is possible to obtain products substituted either
at the Cp ring or at the lateral methyl group. This opens
a novel entry to specifically substituted azaferrocenes
(especially those containing heteroatom substituents)
with potential applications as ligands for homogenous
catalysis.
1
groups. On the other hand, the H NMR spectrum of
4 shows the five-proton singlet of the unsubstituted Cp
ligand and the AB pattern for the diastereotopic protons
of the CH2 group. Two sets of signals are observed,
which may indicate the formation of two diastereomers
in the ꢁ10:3 ratio.
Under the same conditions, lithiated 1 reacted with
4,40-dimethoxybenzophenone to afford a mixture of reg-
ioisomeric products 5 and 6. These compounds were
separated by column chromatography and isolated in
25% and 21% yield, respectively (along with 12% of
recovered 1). Their structures were established by spect-
roscopic methods as well as by X-ray diffraction (vide
infra).
2. Results and discussion
2.1. Quenching of the lithiated 1 with D2O
Finally, it has been found that treatment of lithiated 1
with N,N-dimethylformamide in THF at ꢀ78 ꢀC affords
exclusively fairly unstable aldehyde 7 isolated as an or-
ange–red oil in 22% yield along with the recovered 1
(40%). The substitution at the Cp-ring was deduced
It has been reported [14] that treatment of 1 with sec-
BuLi and TMEDA in THF at ꢀ78 ꢀC for 1.5 h, followed
by quenching with D2O brought about the introduction
of deuterium into the Cp ring (54%), methyl groups
(38%) and in the b-positions of the pyrrolyl ligand (8%).
Now we report that practically the same distribution of
the deuterium label was obtained in the absence of TME-
DA, and when the reaction time with sec-BuLi and TME-
DA was limited to 6 min (2H NMR data). This means that
there is no equilibration between lithio derivatives having
metal in the Cp ring and in the methyl group.
1
from the H NMR spectrum of 7 showing in the region
of d 4–5 ppm three two-proton signals (b-pyrrolyl and
two pairs of the C5H4 protons), as well as a singlet at
2.22 ppm corresponding to six methyl protons and a sin-
glet of the formyl proton at 9.99 ppm.
2.3. Reaction of lithiated 1 with chlorodiphenylphosphine
and diphenyldiselenide
2.2. Reaction of the lithiated 1 with selected carbonyl
compounds
It seemed to us interesting to find out how the lithi-
ated 1 reacts with heteroelectrophiles because such reac-
tions would lead to azaferrocenes containing
heteroatoms in lateral chains, potential chelating ligands
for homogenous catalysis (Scheme 2).
It has been found that quenching of lithiated 1 with
chlorodiphenylphosphine leads a mixture of isomeric
products 8 and 9, having the diphenylphosphino group
bound to the lateral carbon and to the Cp ring, respec-
tively. These products were separated by column chro-
The above data clearly indicate that reaction of 1
with sec-BuLi in THF leads to comparable amounts of
laterally and Cp-lithiated products. However, it has
been found that treatment of a mixture of these com-
pounds with 4-methoxybenzaldehyde gave 2 as the sole
isolable product (obtained in 30% yield along with 50%
of recovered 1). This compound is planar chiral and
contains a stereogenic centre in the lateral chain. Thus
four stereoisomers are possible (two racemic diastereo-
mers). However, 1H NMR data suggested that only
one diastereomer was formed. Its stereochemistry will
be discussed below (Scheme 1).
matography
and
their
structures
confirmed
unequivocally by spectroscopic methods. The 1H
NMR spectrum of 8 displays two signals of the pyrrolyl
b-protons (4.32 and 4.10, each corresponding to one
proton) and a singlet of five Cp protons at 4.16 ppm.

766
K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
OH
C6H4-OMe(4)
N
N
Fe
Fe
CHO
2
7
1.(i)
2. 4-methoxybenzaldehyde
1.(i)
2. DMF
N
Fe
1.(i)
2. 4,4'-dimethoxy-
benzophenone
1. (i)
2. 4-methoxyacetophenone
1
N
N
Fe
Fe
C6H4-OMe(4)
C6H4-OMe(4)
C6H4-OMe(4)
OH
OH
5
3
+
+
C6H4-OMe(4)
C6H4-OMe(4)
N
N
Fe
C6H4-OMe(4)
OH
Fe
OH
4
6
Scheme 1. Reaction of lithiated 1 with carbonyl compunds. (i) sec-BuLi–TMEDA, THF, ꢀ78 ꢀC.
Furthermore, two doublets of diastereotopic CH2 pro-
tons (3.58 and 3.40 ppm) were observed along with a
singlet corresponding to the methyl group (2.26 ppm).
The spectrum of 9 shows in the region of 4–4.5 ppm
three two-protons signals: the singlet at 4.25 ppm (pyr-
rolyl b-protons), and two triplets (4.39 and 4.10 ppm)
assignable to the protons of the monosubstituted Cp lig-
and. The protons of the methyl groups give rise to a sin-
glet (6H) at 2.13 ppm. Compounds 8 and 9 are fairly
unstable in the air and undergo oxidation to the corre-
sponding P-oxides. Formation of such compounds was
evidenced by appearance of signals at ꢁ28 ppm in the
31P NMR spectra (FcCH2P(O)Ph2 shows signal at 29
ppm [15]) and peaks corresponding to M + 16 (M + O)
in the mass spectra of partly oxidized samples.
N
Fe
1.(i)
2. Ph2PCl
1.(i)
2. (PhSe)2
1
PPh2
SePh
N
N
Fe
Fe
10
8
+
+
Similarly, the reaction of lithiated 1 with diphenyl
diselenide afforded a mixture of the laterally- and Cp-
substituted azaferrocenes (10 and 11, respectively).
These compounds were easily separated by column
chromatography and isolated in 26% and 10%, respec-
tively, along with recovered 1 (12%).Their structures
were unambiguously confirmed by spectral and analyti-
cal data.
N
N
Fe
Fe
SePh
PPh2
9
11
Scheme 2. Reaction of lithiated 1 with heteroelectrophiles: (i) sec-
BuLi–TMEDA, THF, ꢀ78 ꢀC.

K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
767
2.4. X-ray diffraction study of compounds 6, 12 and 13
The molecular structures of compounds 6, 12 and 13
are shown in Figs. 1–3.
Most of the synthesized compounds are oils and only
6 afforded crystals suitable for X-ray analysis. However,
we have found that reaction of 2 and 5 with photochem-
ically generated W(CO)5(THF) affords crystalline com-
plexes 12 and 13, for which X-ray quality crystals were
obtained. Crystal data and structure refinement details
are given in Table 1.
Compound 6 forms in the crystal centrosymmetric di-
mers via OH–N hydrogen bonds, linking together two
enantiomers of this compound (Fig. 1).
Compound 12 is a single, racemic diastereomer.
Enantiomers are intercalated and linked by hydrogen
bonds between OH groups and CO ligands (Fig. 2(b)).
The structure shows the absolute configuration of these
enantiomers (S,Rp) and (R,Sp). The lateral chain adopts
an anti-periplanar conformation A, which minimalizes
steric interactions between bulky aryl- and metallocenyl
moieties.
OH
C6H4-OMe(4)
N
(OC)5W
Fe
12
OH
Metallocene
H
N
(OC)5W
Fe
H
C6H4-OMe(4)
C6H4-O Me(4)
Ph-OMe(p)
H
A
OH
13
Conformation A
Table 1
Crystal data and structure refinement for 6, 12 and 13
Compound
6
12
13
Chemical formula
Formula weight
2(C26H27NO3Fe)
914.68
0.71073
C24H21FeNO7W
675.12
0.71073
C31H27FeNO8W
781.24
0.71073
˚
K (A)
T (K)
100(1)
ꢀ
100(1)
P21/c
Monoclinic
100(1)
P21/c
Monoclinic
Space group
Crystal system
Unit cell dimensions
P1
Triclinic
˚
a (A)
10.702(1)
11.400(2)
20.684(2)
94.99(1)
94.30(1)
116.76(1)
2226.1(5)
2
9.080(1)
22.166(2)
11.677(1)
90
11.904(1)
18.361(2)
13.967(2)
90
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
c (ꢀ)
95.76(1)
90
109.51(1)
90
3
˚
V (A )
2338.3(4)
4
1.918
2877.5(6)
4
1.803
Z
Dc (mg/m3)
F(000)
1.365
960
1312
Block
1536
Block
Habit
Crystal size (mm)
l (mmꢀ1
Plate
0.4 · 0.3 · 0.03
0.705
0.4 · 0.3 · 0.3
5.581
0.3 · 0.3 · 0.2
4.552
)
Absorption correction
Maximum and minimum transmission
Type of diffractometer
Diffraction geometry
Analytical
0.870 and 0.573
Analytical
0.712 and 0.257
Analytical
0.8360 and 0.4885
Kuma KM4CCD j-axis diffractometer
x
2.95–28.37
X
x
h Range (ꢀ)
3.27–28.41
14453
5443
3.02–28.43
18891
6720
Number of reflections measured
Number of unique reflections
Rint
18011
9928
0.0412
0.0267
4892[I > 2r(I)]
0.0184
6089[I > 2r(I)]
Number of observed reflections
Refinement method
8022[I > 2r(I)]
Least-squares on F2
613
Number of parameters
Final R indicesa [I > 2r(I)]
Final R indicesa (all data)
Goodness-of-fit (S)
311
383
R1 = 0.0490, wR2 = 0.1143
R1 = 0.0666, wR2 = 0.1214
1.050
R1 = 0.0207, wR2 = 0481
R1 = 0.0255, wR2 = 0.0494
1.058
R1 = 0.0180, wR2 = 0.0391
R1 = 0.0221, wR2 = 0.0400
1.078
ꢀ3
˚
Largest diff. peak and hole e A
0.835 and ꢀ0.438
0.647 and ꢀ1.330
1.207 and ꢀ0.623
n
.
o
1=2
a
P
P
P
P
2
2
R1 = ||Fo ꢀ |Fc||/ |Fo|; wR2 ¼
½wðF 2o ꢀ F 2c Þ ꢂ
½wðF 2oÞ ꢂ
.

768
K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
˚
Fig. 1. ORTEP drawing showing dimers of 6. Selected bond lengths and angles: O(1)–H(1)ꢃ ꢃ ꢃN(2) 2.923(3) A; O(1)–H(1)ꢃ ꢃ ꢃN(2) 176ꢀ; O(4)–
˚
H(4)ꢃ ꢃ ꢃN(1) 2.843(3) A; O(4)–H(4)ꢃ ꢃ ꢃN(1) 161ꢀ.
The observed regioselectivity does not seem to be due
to the lack of the reactivity of one of the regioisomeric
lithio derivatives of 1 toward a given electrophile. In
fact, when reaction mixture after treatment with the
electrophile was treated with D2O, the recovered 1 did
not contain deuterium (checked by MS spectrum). An-
other, yet inexplicable feature of the above reactions is
the recovery in all cases of considerable amounts of
starting 1. The use of a larger excess of sec-BuLi did
not bring about decrease of the amount of recovered
1, but resulted in a sharp decrease of the yields of the
reaction products.
The yields of the above-mentioned reactions are
rather modest, but the products are easily separated
and purified by column chromatography. The lithiation
of 1, followed by reaction with an electrophile consti-
tutes therefore a novel and efficient way to specifically
substituted azaferrocenes, that were so far synthetically
inaccessible.
This conformation also dominates in solution as indi-
cated by the vicinal coupling constants in the –CH–
CH2– system (9.2 and 4.0 Hz) [14].
The molecular packing of compound 12 (Fig. 2(b))
and 13 (not shown) display a network of hydrogen
bonds between OH groups and CO ligands.
3. Discussion and concluding remarks
The results obtained in this work clearly show that
the outcome of the reaction of lithiated 1 with an electr-
ophile depends critically on the nature of this electro-
phile. It is possible to obtain selectively products
coming from either laterally- or Cp-lithiated 1, or mix-
tures of them. Unfortunately, at this stage it is not clear
which structural features of electrophile determine the
regioselectivity of its reaction with lithiated 1. It is wor-
thy noting that similar behaviour was reported for lith-
iated parent azaferrocene. The treatment of this
compound with n-BuLi in THF at ꢀ50 ꢀC, followed
by quenching with iodomethane afforded a mixture of
2- and 10-methylazaferrocene and 10,2-dimethylazaferro-
cene, suggesting that 2- and 10-lithioazaferrocenes are
formed in comparable amounts along with some
amount of 10,2-dilithioazaferrocene [8]. However, when
benzophenone, benzaldehyde, dibenzyl ketone or diiso-
propyl ketone were used as quenchers the exclusive for-
mation of 2-substituted azaferrocenes was observed
[9,10]. On the other hand, reaction of lithiated azaferro-
cene with cyclohexanone afforded exclusively 10-substi-
tuted product [10].
4. Experimental
4.1. General remarks
All reactions were carried out under an atmosphere
of argon. Solvents were dried by using standard proce-
dures. Chromatographic purifications were carried out
on Silica gel 60 (Merck, 230–400 mesh ASTM). The
NMR spectra were determined on Varian Gemini 200
1
BB (200 MHz for H) and Bruker DRX500 (500 MHz
1
for H) in CDCl3 solutions. They were calibrated by

K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
769
(a)
(b)
˚
Fig. 2. ORTEP drawing (a) and intermolecular hydrogen bonds in crystals of 12 (b). The distance O(1)–H(1)ꢃ ꢃ ꢃO(51) is 2.99(4) A and the angle
O(1)–H(1)ꢃ ꢃ ꢃO(51) is 129(4)ꢀ.
using internal Me4Si, chloroform (1H) signal or external
85% H3PO4 (31P) references. IR spectra were recorded
on a FT-IR Nexus Nicolet apparatus. Mass spectra were
run on a Finnigan MAT 95 spectrometer. The combus-
tion analyses were determined by Analytical Services of
the Center of Molecular and Macromolecular Studies of
4.2. Reaction of lithiated 1 with 4-methoxyacetophenone
sec-BuLi (1.4 M in cyclohexane, 2.0 ml, 2.8 mmol)
was added to an argon-saturated solution of 2,5-dime-
thylazaferrocene (508 mg, 2.3 mmol) and TMEDA
(150 ll, 0.98 mmol) in THF (15 ml) at ꢀ78 ꢀC. The or-
ange coloration of the solution rapidly turned brown.
After the mixture was stirred for 1.5 h at ꢀ78 ꢀC, 4-
methoxyacetophenone (771 mg, 5.1 mmol) in 6 ml
THF was added and the stirring was continued for
´ ´
the Polish Academy of the Sciences (Łodz).
2,5-Dimethylazaferrocene and compound 2 were pre-
pared according to the literature procedures ([16] and
[14], respectively).

770
K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
HRMS: m/e = 365.1066 (Calc. for C20H23NO2Fe:
365.1078). Anal. Calc. for C20H23NO2Fe Æ 2H2O: C,
59.86; H, 6.78. Found: C, 60.00; H, 6.27%.
4.3. Reaction of lithiated 1 with 4,40-dimethoxybenzophe-
none
sec-BuLi (1.4 M in cyclohexane, 1.4 ml, 1.9 mmol)
was added to an argon-saturated solution of 1 (310
mg, 1.44 mmol) and TMEDA (80 ll, 0.53 mmol) at
ꢀ78 ꢀC in THF (10 ml). The orange coloration of the
solution rapidly turned brown. After the mixture was
stirred for 1.5 h at ꢀ78 ꢀC, 4,40-dimethoxybenzophe-
none (387 mg, 1.6 mmol) in THF (7 ml) was added
and the stirring was continued for 1.5 h. The reaction
mixture was allowed to warm to room temperature
and poured onto water. Extraction with dichlorometh-
ane, drying over MgSO4 and solvent evaporation gave
brown oil which was subjected to column chromatogra-
phy (ethyl acetate–hexane (5:1) as eluent). The following
fractions were collected:
Fig. 3. ORTEP drawing of 13.
First, containing 5 (orange foam). Yield: 162 mg
(25%). 1H NMR d (CDCl3): 7.32 (AB d, 4H, J = 8.6 Hz,
C6H4), 6.79 (AB d, 4H, J = 8.6 Hz, C6H4), 4.32 (s, 2H,
b-pyrrolyl), 4.12 (bs, 2H, C5H4), 4.09 (bs, 2H, C5H4),
3.77 (s, 6H, OCH3), 2.09 (s, 6H, CH3–pyrrolyl). IR
(CHCl3 m [cmꢀ1]): 3296 (OH), 3007, 2960, 2935, 2839
(C–H). MS (EI, 70 eV) m/e = 457 [M]+. Anal. Calc. for
C26H27O3NFe: C, 68.28; H, 5.95. Found: C, 68.19; H,
6.16%.
Second, containing 6 (orange crystals). Yield: 137 mg
(21%).1H NMR: d (CDCl3): 7.39 (AB d, 2H, J = 8.5 Hz,
C6H4), 7.21 (AB d, 2H, J = 8.5 Hz, C6H4), 6.82 (AB d,
2H, J = 8.5 Hz, C6H4), 6.69 (AB d, 2H, J = 8.5 Hz,
C6H4), 4.92 (s, 1H, OH), 4.25 (s, 1H, b-pyrrolyl), 4.16
(s, 5H, C5H5), 4.14 (s, 1H, b-pyrrolyl), 3.77 (s, 3H,
OCH3), 3.72 (s, 3H, OCH3), 3.68 (d, 1H, J = 14.5 Hz,
CH2), 3.58 (d, 1H, J = 14.5 Hz, CH2), 2.23 (s, 3H,
CH3–pyrrolyl). IR (CHCl3 m [cmꢀ1]): 3334 (OH); 3007,
296, 2935 (C–H). MS (EI, 70 eV) m/e = 457 [M]+, 439
[M ꢀ H2O]+. Anal. Calc. for C26H27O3NFe: C, 68.28;
H, 5.95. Found: C, 68.01; H, 6.16%.
1.5 h. The reaction mixture was allowed to warm to
room temperature and poured onto water. Extraction
with dichloromethane, drying over MgSO4 and solvent
evaporation gave brown oil which was subjected to col-
umn chromatography (ethyl acetate–hexane (5:1) as elu-
ent). The following fractions were collected:
First, containining 3 (orange oil). Yield: 210 mg (24%).
1H NMR d (CDCl3): 7.38 (AB d, 2H, J = 8.8 Hz,
C6H4), 6.83 (AB d, 2H, J = 8.8 Hz, C6H4), ꢁ5.3 (bs,
1H, OH), 4.38 (m, 2H, b-pyrrolyl, C5H4), 4.31 (d, 1H,
J = 2.2 Hz, b-pyrrolyl), 4.09 (m, 1H, C5H4), 4.02 (m,
1H, C5H4), 3.90 (m, 1H, C5H4), 3.79 (s, 3H, OCH3),
2.36 (s, 3H, CH3–pyrrolyl), 2.11 (s, 3H, CH3–pyrrolyl),
1.77 (s, 3H, CH3). IR (CHCl3 m [cmꢀ1]): 3311 (OH);
3007, 2931 (C–H). EIMS (70 eV): m/e = 365 [M]+. Anal.
Calc. for C20H23O2NFe*1/2H2O: C, 64.18; H, 6.46.
Found: C, 64.21; H, 6.52%.
Second (orange oil). This fraction was subjected to a
second chromatography (chloroform as eluent). The two
fractions were collected:
First, containing recovered 1 (orange oil). Yield: 177
mg, (35%). Second, containing 4 as a mixture of diaster-
eomers (10:3 according to 1H NMR) (orange oil). Yield:
108 mg (13%).
Third, containing recovered 1 (orange oil). Yield: 38
mg, (12%).
4.4. Reaction of lithiated 1 with N,N-dimethylformamide
1H NMR d (CDCl3): 7.41 (AB d, J = 8.7 Hz, C6H4),
7.19 (AB d, J = 8.7 Hz, C6H4), 6.86 (AB d, J = 8.7 Hz,
C6H4), 6.74 (AB d, J = 8.7 Hz, C6H4), 4.39 (d, J = 1.9
Hz, b-pyrrolyl), 4.28 (d, J = 1.9 Hz, b-pyrrolyl), 4.23 (d,
J = 1.9 Hz, b-pyrrolyl), 4.11 (s, C5H5), 4.04 (s, C5H5),
3.78 (s, OCH3), 3.72 (s, OCH3), 3.18 (AB, J = 14.0 Hz,
CH2), 3.09 (AB, J = 14.0 Hz, CH2), 2.28 (s, 3H, CH3–pyr-
rolyl), 2.22 (s, 3H, CH3–pyrrolyl), 1.49 (s, 3H, CH3), 1.27
(s, 3H, CH3). IR (CHCl3 m [cmꢀ1]): 3377 (OH); 3014,
2972, 2931 (C–H). MS (EI, 70 eV) m/e = 365 [M]+.
sec-BuLi (1.4 M in cyclohexane, 1.0 ml, 1.4 mmol)
was added to an argon-saturated solution of 2,5-dime-
thylazaferrocene (215 mg, 1.0 mmol) and TMEDA (76
ll, 0.50 mmol) in THF (12 ml) at ꢀ78 ꢀC. The orange
coloration of the solution rapidly turned brown. After
the mixture was stirred for 1.5 h at ꢀ78 ꢀC, fresh dis-
tilled DMF (116 ll, 1.5 mmol) was added and the stir-
ring was continued for 1 h. The reaction mixture was
allowed to warm to room temperature and poured onto

K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
771
water. Extraction with dichloromethane, drying over
MgSO4 and solvent evaporation gave brown oil which
was subjected to column chromatography (chloroform
as eluent). The following fractions were collected:
First, recovered 1 (orange oil). Yield: 86 mg (40%).
Second, containing 7 (orange–red, unstable oil)
Yield: 54 mg (22%).1H NMR: d (CDCl3): 9.99 (s, 1H,
CHO), 4.77 (s, 2H,C5H4), 4.60 (s, 2H, C5H4), 4.46 (s,
2H, b-pyrrolyl), 2.22 (s, 6H, CH3–pyrrolyl). IR (CHCl3,
m [cmꢀ1]): 1684 (CHO); 2958, 2924 (C–H). MS (CI, iso-
butane): m/e = 244 (M + H)+.
(PhSe)2 (624 mg, 2.0 mmol) in THF (5 ml) was added
and the stirring was continued for 2 h. The reaction mix-
ture was allowed to warm to room temperature and
poured onto water. Extraction with dichloromethane,
drying over MgSO4 and solvent evaporation gave brown
oil which was subjected to column chromatography
(ethyl acetate–hexane (5:1) as eluent). The following
fractions were collected:
First (yellow) containing recovered (PhSe)2.
Second, containing 11 (orange oil). Yield: 66 mg
1
(10%). H NMR d (CDCl3): 7.20–7.14 (m, 5H,C6H5),
4.42 (s, 2H, b-pyrrolyl), 4.35 (t, 2H, J = 1.4 Hz, C5H4),
4.33 (t, 2H, J = 1.4 Hz, C5H4), 2.31 (s, 6H, CH3-pyrro-
lyl).HRMS m/e = 370.9859 (Calc. for C17H17NSeFe:
370.9876) Anal. Calc. for C17H17NSeFe: C, 55.17; H,
4.63. Found: C, 54.89; H, 4.59%.
Third, containing 10 (orange oil). Yield: 174 mg
(26%).1H NMR d (CDCl3): 7.52–7.22 (m, 5H, C6H5),
4.42 (d, 1H, J = 1.92 Hz, b-pyrrolyl), 4.32 (d, 1H,
J = 1.92 Hz, b-pyrrolyl), 4.25 (d, 1H, J = 12.4 Hz,
CH2), 4.18 (s, 5H, C5H5), 4.09 (d, 1H, J = 12.4 Hz,
CH2), 2.28 (s, 3H, CH3–pyrrolyl). HRMS m/
e = 370.9892 (Calc. for C17H17NSeFe: 370.9876). Anal.
Calcd. for C17H17NSeFe: C, 55.17; H, 4.63. Found: C,
55.02; H, 4.73%.
4.5. Reaction of lithiated 1with (Ph)2PCl
sec-BuLi (1.4 M in cyclohexane, 1.0 ml, 1.4 mmol)
was added to an argon-saturated solution of 1 (275
mg, 1.4 mmol) and TMEDA (90 ll, 0.59 mmol) in
THF (12 ml) at ꢀ78 ꢀC. The orange coloration of the
solution rapidly turned brown. After the mixture was
stirred for 1.5 h at ꢀ78 ꢀC, chlorodiphenylphosphine
(270 ll, 1.5 mmol) in THF (5 ml) was added and the stir-
ring was continued for 2 h. The reaction mixture was al-
lowed to warm to room temperature and poured onto
water. Extraction with dichloromethane, drying over
MgSO4 and solvent evaporation gave brown oil which
was subjected to column chromatography (ethyl ace-
tate–hexane (5:1) as eluent). The following fractions
were collected:
Fourth, containing recovered 1. Yield: 45 mg, (12%).
4.7. Synthesis of 12
1
First (40 mg), exhibiting complex H and 31P NMR
spectra, which has not been identified.
W(CO)6 (105 mg, 0.3 mmol) dissolved in THF (25
ml) was photolysed with a 200 W high-pressure mercury
lamp for 2 h. The photolyte was treated with 2 (51 mg,
0.14 mmol) and the resulting solution was stirred at
room temperature for 2 h. Removal of solvent, column
chromatography (eluent: chloroform), and crystalliza-
tion from chloroform–hexane afforded 12. Yield: 54
mg (57%).1H NMR: d (CDCl3): 7.41 (AB d, 2H,
J = 8.8 Hz, C6H4), 6.96 (AB d, 2H, J = 8.8 Hz, C6H4),
4.71 (m, 1H, CH), 4.71 (d, 1H, J = 2.4 Hz, b-pyrrolyl),
4.63 (d, 1H, J = 2.4 Hz, b-pyrrolyl), 4.26 (s, 5H,
C5H5), 3.84 (s, 3H, OCH3), 3.51 (dd, 1H, J = 15.6 Hz,
J = 4.7 Hz, CH2), 3.23 (dd, 1H, J = 15.6 Hz, J = 8.3
Second, containing 8 (orange oil). Yield: 60 mg
(13%). 1H NMR: d (CDCl3): 7.34–7.8 (m, 10H, C6H5),
4.32 (s, 1H, b-pyrrolyl), 4.16 (s, 5H, C5H5), 4.10 (s,
1H, b-pyrrolyl), 3.58 (d, J = 11.0 Hz, 1H, 1/2CH2),
3.40 (d, J = 11.0 Hz, 1H, 1/2CH2), 2.26 (s, 3H, CH3).
31P NMR (CDCl3): ꢀ13.0. HRMS: m/e = 399.0822
(Calc. for C23H22NPFe: 399.0839).
Third, containing 9 (orange oil). Yield: 120 mg,
(25%). 1H NMR: d (CDCl3): 7.78–7.22 (m, 10H,
C6H5), 4.39 (t, J = 1.4 Hz, 2H, C5H4), 4.25 (s, 2H, b-pyr-
rolyl), 4.10 (t, J = 1.4 Hz, 2H, C5H4), 2.13 (s, 6H, CH3–
pyrrolyl). 31P NMR (81 MHz, CDCl3): ꢀ18.24. HRMS:
m/e = 399.0821 (Calc. for C23H22NPFe: 399.0839).
Anal. Calc. for C23H22NPFe: C, 69.19; H, 5.55. Found:
C, 69.11; H, 5.65%.
Hz, CH2), 2.63 (s, 3H, CH3–pyrrolyl). IR (CHCl3
m
[cmꢀ1]): 3330 (OH); 1923 (W–CO). MS (EI, 70 eV)
m/e = 591 [M ꢀ 3CO]+, 535 [M ꢀ 5CO]+, 351
[M ꢀ W(CO)5]+. Anal. Calc. for C24H21O7NFeW: C,
42.67; H, 3.14. Found: C, 42.57; H, 3.45%.
Second, containing recovered 1 (orange oil). Yield: 37
mg (13%).
4.6. Reaction of lithiated 1 with diphenyl diselenide
4.8. Synthesis of 13
sec-BuLi (1.4 M in cyclohexane, 1.4 ml, 1.9 mmol)
was added to an argon-saturated solution of 2,5-dime-
thylazaferrocene (387 mg, 1.8 mmol) and TMEDA
(135 ll, 0.89 mmol) in THF (12 ml) at ꢀ78 ꢀC. The or-
ange coloration of the solution rapidly turned brown.
After the mixture was stirred for 1.5 h at ꢀ78 ꢀC,
W(CO)6 (140 mg, 0.4 mmol) dissolved in THF (25
ml) was photolysed with a 200 W high-pressure mercury
lamp for 2 h. The photolyte was treated with 5 (89 mg,
0.19 mmol) and the resulting solution was stirred at
room temperature for 2 h. Removal of solvent, column
chromatography (eluent: chloroform), and crystalliza-

772
K. Kowalski et al. / Journal of Organometallic Chemistry 690 (2005) 764–772
tion from chloroform–hexane afforded 13. Yield: 86 mg
(58%).
charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK (fax: +44 1223 336 033; e-mail:
deposit@ccdc.cam.ac.uk).
1H NMR d (CDCl3): 7.07 (AB d, 4H, J = 6.4 Hz,
C6H4), 6.79 (AB d, 4H, J = 6.4 Hz, C6H4), 4.51 (s, 2H,
b-pyrrolyl), 4.37 (s, 2H, C5H4), 4.24 (s, 2H, C5H4),
3.78 (s, 6H, OCH3), 2.40 (s, 6H, CH3–pyrrolyl). IR
(CHCl3 m [cmꢀ1]): 3300 (OH); 1923 (W–CO). MS
(EI,70eV) m/e = 638 [M ꢀ 4CO ꢀ OCH3]+. Anal. Calc.
for C31H27O8NFeW: C, 47.66; H, 3.48. Found: C,
47.62; H, 3.64%.
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