Syntheses, structural elucidation and reactions of allylamino compounds of the type, [η5-C5R5(CO) 2Fe(NH2CH2CHCH2)]BF4

Article abstract of DOI:10.1016/j.poly.2012.03.039

The reaction of 3-aminoprop-1-ene (allylamine) with the etherate complexes [(η⁵-C₅R₅)(CO)₂Fe(L)] ⁺ (R = H; L = Et₂O; R = CH₃; L = THF) have been investigated and found to give air stable allylamino complexes [(η⁵-C₅R₅)(CO)₂Fe(NH ₂CH₂CHCH₂)]⁺ (R = H (3) or CH ₃ (4)) with the vinyl functionality pendant on the alkyl chain. These complexes have been isolated as the tetrafluoroborate salts. They undergo halogenation reactions on the pendant vinyl group to give high yields of the dihalopropylamino complexes [(η⁵-C₅H ₅)(CO)₂Fe{NH₂CH₂CH(X)CH ₂X}]⁺ (X = Cl (5), Br (6)) and [{η⁵-C ₅(CH₃)₅}(CO)₂Fe{NH ₂CH₂CH(Br)CH₂Br}]⁺, (7), respectively. Complexes 3 and 4 also react with the etherate complexes [(η⁵-C₅R₅)(CO)₂Fe(L)] ⁺ to yield dinuclear complexes of the type, [(η⁵- C₅R₅)(CO)₂Fe(NH₂CH ₂CHCH₂)Fe(CO)₂(η⁵-C ₅R₅′)]²⁺ (R not necessarily equal to R′), in which the two iron moieties are in different electronic environments. The NMR and IR data of the dinuclear complexes show that the allylamine ligand bridges the two metal systems. It is coordinated to the metal on one end via the nitrogen of the amine functionality in a η¹- fashion and on the other end via the vinylic functionality in a η²-fashion forming a chiral metallacyclopropane type structure. The reaction of the dinuclear salt [{(η⁵-C₅H ₅)(CO)₂Fe}₂(NH₂CH ₂CHCH₂)](BF₄)₂ with NaI in acetone gives [(η⁵-C₅H₅)(CO)₂Fe(NH ₂CH₂CHCH₂)]I and [(η⁵-C ₅H₅)Fe(CO)₂I] indicating that the iodide displaces the η²-coordinated metal center. All these compounds have been fully characterized. The molecular structures of [3][BF₄], [4][BF₄] and [7][BF₄] have been determined by single crystal X-ray diffraction.

Full text of DOI:10.1016/j.poly.2012.03.039

Polyhedron 40 (2012) 81–92
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Polyhedron
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Syntheses, structural elucidation and reactions of allylamino compounds of the
type, [g
5-C5R5(CO)2Fe(NH2CH2CH@CH2)]BF4
b
a
Cyprian M. M’thiruaine a, Holger B. Friedrich a, , Evans O. Changamu , Bernard Omondi
⇑
a School of Chemistry, University of KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa
b Chemistry Department, Kenyatta University, P.O. Box 43844, Nairobi, Kenya
a r t i c l e i n f o
a b s t r a c t
g
5-C5R5)(CO)2Fe(L)]+
Article history:
The reaction of 3-aminoprop-1-ene (allylamine) with the etherate complexes [(
(R = H; L = Et2O; R = CH3; L = THF) have been investigated and found to give air stable allylamino com-
plexes [(
5-C5R5)(CO)2Fe(NH2CH2CH@CH2)]+ (R = H (3) or CH3 (4)) with the vinyl functionality pendant
Received 20 January 2012
Accepted 27 March 2012
Available online 6 April 2012
g
on the alkyl chain. These complexes have been isolated as the tetrafluoroborate salts. They undergo
halogenation reactions on the pendant vinyl group to give high yields of the dihalopropylamino
g g
5-C5H5)(CO)2Fe{NH2CH2CH(X)CH2X}]+ (X = Cl (5), Br (6)) and [{ 5-C5(CH3)5}(CO)2-
Keywords:
Allylamine
Dihaloallylamino complexes
Halogenations
Chiral compounds
complexes [(
Fe{NH2CH2CH(Br)CH2Br}]+, (7), respectively. Complexes 3 and 4 also react with the etherate complexes
[(
5-C5R5)(CO)2Fe(L)]+ to yield dinuclear complexes of the type, [( 5-C5R5)(CO)2Fe(NH2CH2CH@CH2)Fe(-
CO)2(
5-C5R50)]2+ (R not necessarily equal to R0), in which the two iron moieties are in different electronic
g
g
g
environments. The NMR and IR data of the dinuclear complexes show that the allylamine ligand bridges
the two metal systems. It is coordinated to the metal on one end via the nitrogen of the amine function-
ality in a
chiral metallacyclopropane type structure. The reaction of the dinuclear salt [{(
Fe}2(NH2CH2CH@CH2)](BF4)2 with NaI in acetone gives [(
5-C5H5)(CO)2Fe(NH2CH2CH@CH2)]I and
[(
5-C5H5)Fe(CO)2I] indicating that the iodide displaces the 2-coordinated metal center. All these com-
g
1-fashion and on the other end via the vinylic functionality in a
g
2-fashion forming a
5-C5H5)(CO)2-
g
g
g
g
pounds have been fully characterized. The molecular structures of [3][BF4], [4][BF4] and [7][BF4] have
been determined by single crystal X-ray diffraction.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
(
g
5-C5H5)]+ [10]. The longer chain polymethylene complexes [(g5
C5H5)(CO)2Fe{CH2@CH(CH2)nꢀ1CH2}Fe(CO)2(
5-C5H5)]+ (n = 4–10)
have been prepared by b hydride abstraction from the neutral
dinuclear polymethylene complexes [{(
5-C5H5)(CO)2Fe}2{
CH2(CH2)nCH2}] and these studies have clearly shown that the vinyl
group is bonded to the metal in a
2-fashion [11,12].
The reaction of the metal allyl complex [(
Fe(CH2CH@CH2)] with HCl was reported by Green and Nagy to yield
the cationic complex [(
5-C5H5)(CO)2Fe( 2-CH2@CHCH2)]+Clꢀ [3].
However, the reaction of HCl with longer chain alkenyl complexes
[(
5-C5H5)(CO)2Fe{(CH2)nCH@CH2}] (n = 2, 3) was reported to
yield the chlorido complex [(
5-C5H5)(CO)2FeCl] as well as their
corresponding chloroalkenes [2]. Busetto et al. found that the
-methoxyethyl complex [(
5-C5H5)(CO)2Fe(CH2CH2OCH3)] reacts
with HCl to give the cationic complex [(
5-C5H5)(CO)2-
Fe(CH2CH2)]+, rather than [( 5-C5H5)(CO)2Fe(CH2CH2Cl)] [13]. The
reaction of [(
5-C5H5)(CO)2Fe{ 1-CH2N(CH3)2}] with CH3COCl has
also been reported to occur via a carbon–nitrogen bond cleavage
to produce [(
5-C5H5)(CO)2Fe(CH2Cl)] [14]. This observation sug-
gests that it is difficult to prepare secondary halide complexes of
the type [(
5-C5H5)(CO)2Fe{CH2)nCH(X)CH3}] by hydrohalogen-
ation of metal alkenyl complexes. However, the primary halide
-
g
The metal allyl and alkenyl complexes [(g
5-C5R5)(CO)2-
Fe{(CH2)nCH@CH2}] (R = H, CH3; n > 0) have been known for a long
time [1]. They are mainly synthesized by displacement of halides
from haloalkenes by the anion [(
g
l-
g
5-C5R5)Fe(CO)2]ꢀ [2–7]. They
g
form an important class of organometallic compounds from which
g
5-C5H5)(CO)2-
other important compounds are prepared. For instance, the alkenyl
complexes [(
2–5, 7) have been shown to undergo an oxidative-hydroboration
reaction to yield alkylalcohol complexes [8], while [(
5-C5H5)(CO)2-
Fe{(CH2)nCH@CH2}] (n = 2–4, 6) reacts with Ph3CPF6 to give
2-(
-diene) complexes [9].
The allyl complex [(
5-C5H5)(CO)2Fe(CH2CH@CH2)] has been re-
ported to undergo condensation with the cationic ethylene complex
g
5-(C5R5)(CO)2Fe{(CH2)nCH@CH2}] (R = H, CH3; n =
g
g
g
g
g
g
a,x
g
r
g
g
[(
[(
g
g
5-C5H5)(CO)2Fe(
g
2-CH2@CH2)]+ to give a dinuclear complex
5-C5H5)]+ [6], as
5-C5H5)(CO)2-
5-C5H5)(CO)2Fe(CH2@CHCH2CH2)Fe(CO)2
g
5-C5H5)(CO)2Fe(CH2@CHCH2CH2CH2)Fe(CO)2(
g
g
g
has the allyl complex with the carbenoid complex [(
g
Fe@CH2]+ to give [(
g
g
g
⇑
Corresponding author. Tel.: +27 312603107; fax: +27 312603091.
E-mail address: friedric@ukzn.ac.za (H.B. Friedrich).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.03.039

82
C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
complexes of the type [(
g
5-C5H5)(CO)2Fe{(CH2)nCH2X}] are well
from the solution after 6 h of reaction. It is easily isolated by filtra-
tion, contrary to the reported remarkable difficulty encountered in
the isolation of neutral alkenyl complexes [4]. Complex 3 was ob-
tained as a yellow microcrystalline solid which was insoluble in
hexane and diethyl ether but very soluble in acetone, methanol,
water and acetonitrile. It is relatively stable in the solid state and
when in nitrogen saturated solutions. However, it undergoes slow
photodecomposition when exposed to light to form a brown
unidentified substance.
known and they are conveniently prepared by the reaction of
Na[( -dihaloalkanes
5-C5H5)Fe(CO)2] with an equivalent of
[15–17].
Bromination of the allyl complex [(
5-C5H5)(CO)2Fe(CH2CH-
CH2)], followed by deprotonation provides the compound
[(
5-C5H5)(CO)2Fe( 2-CH2@CHCH2Br)]PF6 [18], which can alterna-
tively be obtained from the reaction of Na[(
5-C5H5)Fe(CO)2] with
-dibromopropane followed by b hydride abstraction [19].
Other bromination products reported are [(
5-C5H5)(CO)2Fe(g2
CH2CH@CHBr)] [1], [(
5-C5H5)(CO)2Fe{ 2-CH2@C(CH3)CH2Br}]
[18] and [(
5-C5H5)(CO)2Fe( 2-CH@CHCHBrCH2CH2)]PF6 [20]. It
g
a,x
g
g
g
g
a,x
g
-
Similarly, the THF complex [{
reacted with one equivalent of 3-amino-1-propene to give
[{
5-C5(CH3)5}(CO)2Fe(NH2CH2CH@CH2)]+, 4, in 78% yield. Unlike
g
5-C5(CH3)5}(CO)2Fe(THF)]+, 2,
g
g
g
g
g
is also well established that molecular halogens cleave iron–carbon
complex 3, complex 4 exhibited high solubility in dichloromethane
and stability in the solid state, as well as in solution. This is ex-
pected, owing to the presence of the electron releasing pentameth-
ylcyclopentadienyl ligand. No evidence of the coordination
occurring at the C@C bond was obtained. When two or more equiv-
alents of the ether complex were used, mixtures of the mononu-
bonds leading to cyclopentadienyl(halo)iron dicarbonyl [21–25].
The dihaloalkyl complexes of the type [(
CH(X)CH2X}] have not been reported, although the alkenyl com-
plexes [(
5-C5H5)(CO)2Fe{(CH2)nCH@CH2}] are well known [2,7].
g
5-C5H5)(CO)2Fe{(CH2)n
g
Halogenation is an important chemical transformation, particularly
in drug design, because it is known to enhance membrane binding
and permeation [26].
clear [(
g
5-C5R5)(CO)2Fe(NH2CH2CH@CH2)]+ and the dinuclear
complex [{(
g
5-C5R5)(CO)2Fe}2(NH2CH2CH@CH2)]2+ were formed.
Reactions of amines are characterized by high regioselectivity
with respect to other electron donor systems such as those with
It was difficult to isolate the dinuclear complex in its pure form.
However, an analytically pure sample of the dinuclear complex
p-bonds. They are good electron donors and therefore they bind
can be obtained from the reaction of [(
Fe(NH2CH2CH@CH2)]BF4 with an equimolar amount of the ether
compound [(
5-C5R5)(CO)2Fe(L)]BF4.
Complexes 3 and 4 resemble the neutral allyl complexes of the
type [(
5-C5H5)(CO)2Fe{(CH2)nCH@CH2}] reported by various
g
5-C5R5)(CO)2-
strongly to the metal. This implies that aminoalkenes can be teth-
ered to the metal center leaving the vinyl function free. Thus addi-
tion reactions, such as halogenations, could take place on the vinyl
functionality without cleaving the metal–nitrogen bond and this
g
g
would provide
compounds.
a
route to
a
new class of organometallic
authors [2,4,5,7] in the sense that they have a terminal double
bond on the alkyl chain. However, they are different in that the
allylamino complexes are cationic and contain both amino and ter-
minal double bond functionalities in the same molecule. Therefore,
they can be regarded as ligand supported metal–nitrogen moieties
The chromium complexes, [(
g
5-C5H5)(NO)Cr(NH2CH2CH@
CH2)2]+Iꢀ and [( 5-C5H5)(NO)Cr(NH2CH2CH@CH2)I] reported by
g
Legzdins et al. [27], and the palladium complex [PdCl2
(NH2CH2CH@CH2)2] reported by Hayes et al. [28] are examples of
allylamino complexes that have appeared in literature. There are
no reports whatsoever about allylamino complexes of iron and
no reports about dihaloalkylamino metal complexes. Herein we re-
in which the metal is
r-bonded to an aliphatic aminoalkyl group
with a reactive pendant vinyl group. The pendant vinylic function-
ality is accessible to electrophiles through which various new iron–
organometallic complexes can be synthesized. As will be seen in
the following sections, allylamino complexes may react by addi-
tion of electrophiles across the double bond and by coordination
of the C@C bond giving rise to new chiral complexes. The NMR,
IR and elemental analysis characterization data for 3 and 4 are gi-
ven in Section 4.
port the new allylamino complexes of the type [(g
5-C5R5)(CO)2-
Fe(NH2CH2CH@CH2)]+ (R = H, CH3) and on their reactions with
electrophilic reagents.
2. Results and discussion
Complex 3 shows IR carbonyl bands at 2051 and 2004 cmꢀ1 (cf.
those of complex 4 observed at 2029 and 1983 cmꢀ1). This is a
characteristic region for carbonyl compounds with auxiliary li-
gands that are strong electron donors such as amines [29–31], thi-
ols [32] or phosphines [33]. Characteristic peaks assignable to N–H
asymmetric and symmetric stretching modes were observed at ca.
3310 and 3279 cmꢀ1, respectively. A peak due to the N–H bending
mode was observed at ca. 1605 cmꢀ1, while a characteristic weak
band assignable to uncoordinated C@C stretching mode was
2.1. Preparation of the complexes [(g5
C5R5)(CO)2Fe(NH2CH2CH@CH2)]+ (R = H, CH3)
-
The reaction of [(
g
5-C5H5)(CO)2Fe(OEt2)]BF4, 1, with an
equimolar amount of 3-amino-1-propene at room temperature re-
sulted in the formation of the allylamino complex [(g
5-C5H5)(CO)2-
Fe(NH2CH2CH@CH2)]+, 3, in 98% yield (Scheme 1). The product is
partially soluble in dichloromethane, causing it to crystallize out
R
R
+
+
R
R
R
R
H2N
R
R
R
R
Fe
L
Fe
NH2
OC
OC
CH2Cl2
R. T
CO
CO
(3) R = H
(1) R = H; L = Et2O
(2) R = CH3; L = THF
(4) R = CH3
Scheme 1. Reactions of etherate complexes with allylamine.

C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
83
observed at ca. 1640 cmꢀ1. Peaks assignable to @CH out-of-plane
bending vibrations were observed at 948 and 682 cmꢀ1 [34] in
the IR spectrum of complex 3 and at 927 and 663 cmꢀ1 in the spec-
trum of complex 4. These bands were absent in the infrared spectra
of halogenated and olefin-coordinated compounds (Sections 2.2
and 2.3).
The 1H NMR spectra of both complexes 3 and 4 show well re-
solved characteristic olefinic proton peaks. A multiplet assignable
to the CH@ proton was observed at ca. 5.81 ppm and two doublets
at 5.28 and 5.23 ppm, each integrating for one proton, assignable to
two non equivalent @CH2 protons. These values are within the
range reported for alkenyl complexes [2,5,35]. The methylene pro-
tons alpha to the amine group exhibited a quartet at ca. 2.95 ppm
3
with a coupling constant JHH = 6.51 Hz. The 13C NMR spectra of
both compounds clearly show peaks corresponding to the vinylic
carbon in the expected region above 115 ppm. All peaks assignable
to allylamino protons slightly shifted upfield upon changing from
(g g
5-C5H5) to { 5-C5(CH3)5}. However, no significant change was
noted in the 13C NMR spectra.
2.1.1. The molecular structures of compounds [3][BF4] and [4][BF4]
Single crystal X-ray diffraction was used to determine the abso-
lute structures of complexes 3 and 4. Molecular diagrams for the
two complexes are given in Figs. 1 and 2, respectively. Selected
bond distances and angles are provided in Table 1, while the X-
ray crystallographic data can be found in Table 2. [3][BF4] crystal-
lizes as brown blocks, while [4][BF4] crystallizes as brown plates.
The asymmetric units of both [3][BF4] and [4][BF4] contain the
Fig. 2. The structure of [4][BF4] showing the atom-numbering scheme. Displace-
ment ellipsoids are drawn at 40% probability level and H atoms are shown as small
spheres.
molecular cations [(
g
5-C5H5)(CO)2Fe(NH2CH2CH@CH2)]+ and
5-C5(CH3)5}(CO)2Fe(NH2CH2CH@CH2)]+, respectively, and the
Table 1
[{g
Selected bond lengths and angles for [3][BF4] and [4][BF4] (Å, °).
counteranion, BF4ꢀ. Both compounds have the familiar ‘‘pseudo-
octahedral three-legged piano stool’’ structures (see Figs. 1 and
2). The five cyclopentadienyl ring carbon atoms occupy the apical
positions, while the two C@O and allylamine ligands occupy the
basal positions of the piano stool.
[3][BF4]
[4][BF4]
[3][BF4]
[4][BF4]
Fe–N
2.018(4)
1.780(5)
1.789(5)
1.138(6)
1.136(6)
1.484(8)
1.300(9)
1.496(8)
1.715
2.029(1)
1.784(2)
1.793(2)
1.136(2)
1.133(2)
1.491(2)
1.320(3)
1.320(3)
1.726
Fe–N–C
N–C–C
C–C@C
117.0(3)
112.3(4)
123.4(7)
95.0(2)
93.3(2)
94.1(2)
123.4
118.6(1)
113.1(1)
123.6(2)
94.89(8)
93.94(7)
92.06(7)
125.5
Fe–Ccarbonyl
Fe–Ccarbonyl
C–O
C–O
N–C
C@C
C–Callyamine
Cg. . .Fe
C–Fe–C
Coordination of the allylamine occurs via the nitrogen atom
N–Fe–C
N–Fe–C
Cg. . .Fe–N
Cg. . .Fe–C
Cg. . .Fe–C
resulting in a formal
r-bond between the Fe atom and the allyla-
mine N atom. The Fe–N bond distance in 3 is slightly shorter
121.9
121.6
122.1
120.4
Cg1 and Cg2 are the centroid of the atoms forming the (
g
5-C5H5) and {
g
5-C5(CH3)5}
rings, (C1, C2, C3, C4 and C5).
[2.0180(4) Å] compared to the same distance in 4 [2.0294(14) Å],
but both are comparable to those of related aminocyclopentadie-
nylirondicarbonyl complexes, 2.017(8) Å for [(g
5-C5H5)(CO)2-
Fe{NH2(CH2)2CH3}]BF4, 2.013(2) Å for [(
(CH2)3CH3}]BF4 [29] and 2.006(2) Å for [{(
g
g
5-C5H5)(CO)2Fe{NH2
5-C5H5)(CO)2Fe}2{
l-
NH2(CH2)2NH2}](BF4)2 [36], as well as those of amino pentameth-
ylcyclopentadienylirondicarbonyl complexes, 2.022(15) Å for
[{
[{{
g
g
5-C5(CH3)5}(CO)2Fe{NH2(CH2)2CH3}]BF4 and 2.0202(14) Å for
5-C5(CH3)5}(CO)2Fe}2{
l-NH2(CH2)3NH2}](BF4)2 [31]. The Fe–
Ccarbonyl bond distances are similar in both complexes and are
typical of most iron carbonyl complexes (1.78(3) Å) [37]. The allyl-
amine C@C (vinyl) bond distances are 1.300(9) and 1.320(3) Å in
[3][BF4] and [4][BF4], respectively. These are slightly shorter than
a formal C@C double bond (1.34 Å) [38,39] but close to calculated
distances for a terminal C@C bond; 1.315 Å for ethylene, 1.316 Å
for propene and 1.321 Å for 2-methylpropene [40].
Figs. 3 and 4 are packing diagrams for [3][BF4] and [4][BF4],
respectively. In the crystal of [3][BF4], the cations and the anions
are connected by two C–HꢁꢁꢁF intermolecular interactions
[C(8)ꢁꢁꢁF(3) and C(10)ꢁꢁꢁF(1)] resulting in chains that run in the crys-
tallographic a axis. These chains are connected by N–HꢁꢁꢁF intermo-
lecular interactions [N(1)ꢁꢁꢁF(4)] resulting in rings that can be
Fig. 1. The structure of compound [3][BF4] showing the atom-numbering scheme.
Displacement ellipsoids are drawn at 40% probability level and H atoms are shown
as small spheres.

84
C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
Table 2
Crystal data and structure refinement for compound [3][BF4], [4][BF4] and [7][BF4].
Compound
[3][BF4]
10H12BF4FeNO2
320.87
173(2)
[4][BF4]
[7][BF4]
Empirical formula
Formula weight
T (K)
C
C15H22BF4FeNO2
391.00
173(2)
C15H22BBr2F4FeNO2
550.82
100(2)
k (Å)
0.71073
monoclinic
C2/c
0.71073
0.71073
Crystal system
Space group
Unit cell dimension
a (Å)
b (Å)
c (Å)
triclinic
triclinic
ꢀ
ꢀ
P1
P1
15.250(3)
8.8443(17)
18.981(4)
90
93.209(5)
90
2556.2(8)
8
1.668
9.5051(2)
9.5487(3)
11.0937(3)
64.913(2)
84.663(2)
73.277(2)
872.84(4)
2
9.3954(10)
10.5527(11)
11.0867(12)
88.6930(10)
79.3410(10)
66.3740(10)
988.09(18)
2
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalc (mg mꢀ3
)
1.488
0.910
404
1.851
4.852
544
Absorption coefficient (mmꢀ1
F(000)
)
1.224
1296
Crystal size (mm)
Theta range for data collection (°)
0.39 ꢂ 0.29 ꢂ 0.13
0.47 ꢂ 0.30 ꢂ 0.15
0.30 ꢂ 0.25 ꢂ 0.20
2.15–28.00
2.03–28.00
1.87–28.74
Index ranges
h
k
l
ꢀ20 ? 20
ꢀ12 ? 12
ꢀ12 ? 12
ꢀ11 ? 11
ꢀ12 ? 12
ꢀ13 ? 13
ꢀ24 ? 25
ꢀ14 ? 11
ꢀ14 ? 14
Reflections collected
Independent reflections
Internal fit
9761
8448
11875
3083
Rint = 0.0618
integration
4204
Rint = 0.0366
integration
4698
Rint = 0.0206
multi-scan
Absorption correction
Transmission factor (Tmin; Tmax
Refinement method
Parameters
)
0.6469; 0.8571
full-matrix least-squares on F2
172
0.6742; 0.8755
full-matrix least-squares on F2
222
0.3238; 0.4436
full-matrix least-squares on F2
276
Goodness-of-fit on F2
1.113
1.029
1.091
Final R indices [I > 2
R indices (all data)
r
(I)]
R1 = 0.0675, wR2 = 0.2098
R1 = 0.0840, wR2 = 0.2188
2.327 and ꢀ0.618
R1 = 0.0322, wR2 = 0.0802
R1 = 0.0422, wR2 = 0.0849
0.508 and ꢀ0.258
R1 = 0.0410, wR2 = 0.0909
R1 = 0.0475, wR2 = 0.0931
1.550 and ꢀ0.905
Largest difference in peak and hole (e Åꢀ3
)
Fig. 3. Crystal packing of [3][BF4] viewed down the crystallographic b-axis showing N–H. . .F, C–H. . .F and p. . .p intermolecular interactions.
described by a R44 graph set notation. The chains are further stabi-
lized by N–HꢁꢁꢁF [N(1)ꢁꢁꢁF(2)] and C–HꢁꢁꢁF [C(4)ꢁꢁꢁF(3)] (Fig. 3) con-
necting the chains and rings in the b crystallographic direction,
In the crystal of [4][BF4], the cations and anions are connected
through a N–HꢁꢁꢁF, a C–HꢁꢁꢁF and two C–HꢁꢁꢁO intermolecular inter-
actions (Table 3) resulting in chains that run diagonally through
the unit. C(13)–H(13B)ꢁꢁꢁO(1) connects two centrosymmetrically
related cations with an inversion center between the two mole-
cules. C(7)–H(7C)ꢁꢁꢁO(1) also connects the same cations with the
O atom being bifurcated. N(2)–H(2A)ꢁꢁꢁF(2) and N(2)–H(2B)ꢁꢁꢁF(3)
and
p
ꢁꢁꢁ intermolecular interactions [Cg1ꢁꢁꢁCg1 = 3.375(4) Å, sym-
p
metry code; ꢀx, y, ½ ꢀ z]. This mode of packing is similar to that
observed in the compound [(
[29].
g
5-C5H5)(CO)2Fe{NH2(CH2)2CH3}]BF4

C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
85
resulting in a racemic mixture of (R) and (S) enantiomers as shown
in Scheme 3. This is indeed further corroborated by the single crys-
tal structure of compound [7][BF4] (Fig. 5) and the NMR data dis-
cussed below.
The success of the halogenation reactions of complexes 3 and 4
was marked by the disappearance of the strong IR band between
920 and 950 cmꢀ1 and weak IR bands at ca. 1640 cmꢀ1 which cor-
respond to @CH out-of-plane bending and C@C stretching vibra-
tions, respectively. The infrared spectrum of compound [5][BF4]
exhibited a characteristic band assignable to C–Cl at 746 cmꢀ1
,
while compound [6][BF4] showed a vibration band corresponding
to C–Br stretching at 652 cmꢀ1, which, as expected, is at a lower
wavenumber than that corresponding to C–Cl. A similar peak
was observed in the infrared spectrum of compound [7][BF4] at
670 cmꢀ1. There was no significant variation in the carbonyl bands
upon halogenation, indicating that the halogen atoms were added
to the vinyl group which is far from the metal and therefore the
electron density on the metal center was not significantly affected.
As expected for chiral molecules, the protons of the
a-CH2
group neighboring the chiral center CHX (Scheme 3) are diastereo-
topic and they show two well separated multiplets at around 3.00
and 2.77 ppm (
D
d ꢃ 0.2 ppm), each integrating for one proton. The
Fig. 4. A perspective of [4][BF4] showing N–H. . .F, C–H. . .F, C–H. . .O and
intermolecular interactions as indicated by dashed and dotted lines.
p–p
peaks corresponding to CHX and CH2X were observed at around
4.28 and 3.86 ppm, respectively. This corresponds to an upfield
shift of 1.54 and 1.38 ppm relative to the peaks due to CH@ and
@CH2 of the starting material, respectively, indicating loss of
anisotropy upon halogenation. The 13C NMR data for compounds
[5][BF4], [6][BF4] and [7][BF4] were assigned with the help of 2D
NMR experiments. As expected, these data show that the position
Table 3
Intermolecular interactions geometry for compounds [3][BF4] and [4][BF4] (Å, °).
D–H. . .A
D–H H. . .A D. . .A
D–H. . .A Symmetry
operator
of the peaks due to CO and (g
5-C5H5) are independent of the type
of halide in the molecule. The 13C NMR spectrum of compound
[6][BF4] shows a peak assignable to the terminal carbon neighbor-
ing bromine at 31.2 ppm which is 15.1 ppm upfield relative to that
of the similar carbon neighboring chlorine in the 13C NMR spec-
trum of compound [5][BF4], as expected, because chlorine is signif-
icantly more electronegative than bromine.
[3][BF4]
N(1)–H(1A). . .F(4)
N(1)–H(1B). . .F(2)
C(4)–H(4). . .F(3)
C(8)–H(8A). . .F(3)
C(10)–H(10B). . .F(1) 0.95 2.55 3.407(9) 151
[3][BF4]
0.92 2.13 3.027(5) 165
0.92 2.08 2.983(5) 166
0.95 2.42 3.213(6) 141
0.99 2.43 3.378(6) 159
x, 1 ꢀ y, ½ ꢀ z
½ ꢀ x, ꢀ½ + y, ½ ꢀ z
ꢀx, y, ½ ꢀ z
½ ꢀ x, ½ + y, ½ ꢀ z
1 ꢀ x, y, ½ ꢀ z
N(2)–H(2A). . .F(2)
C(7)–H(7C). . .O(1)
C(13)–H(13B). . .O(1) 0.99 2.57 3.4824
C(8)–H(8B). . .F(2) 0.98 2.52 3.3923
0.92 2.27 3.0134
0.98 2.60 3.5645
137
169
152
149
ꢀx, 1 ꢀ y, 1ꢀz
ꢀx, 2 ꢀ y, ꢀz
ꢀx, 2 ꢀ y, ꢀz
x, 1 + y, ꢀ1 + z
No reaction was noted between the allylamino complexes and
formic acid or tetrafluoroacetic acid, even when a large excess of
these reagents was used and the mixtures stirred for 24 h at room
temperature or at refluxing temperatures. There was also no reac-
tion between the allylamino complexes and hydrogen chloride gas.
Interestingly, although amines are weak bases, the allylamino
complexes were recovered intact at the end of the period by evap-
orating the mixture to dryness, followed by extraction using
dichloromethane and precipitation by diethyl ether. The coordina-
tion of the amine functionality probably severely weakens the
basic properties of the allylamine, thereby stabilizing the metal-
coordinated compounds in acidic medium.
then connects the pairs of cations to complete the chains. The
chains are then linked through weak intermolecular interac-
pꢁꢁꢁp
tions [CgꢁꢁꢁCg = 3.9994 Å, symmetry code; 1 ꢀ x, 1 ꢀ y, ꢀz] (Fig. 4).
2.2. Halogenation of complexes 3 and 4
The cationic allylamino complexes [(
CH@CH2)]+ (R = H (3), CH3 (4)) react readily with Cl2 and Br2
g
5-C5R5)(CO)2Fe(NH2CH2-
2.2.1. Crystal structure of [{g5
C5(CH3)5}(CO)2Fe{NH2CH2CH(Br)CH2Br}]BF4, [7][BF4]
-
in CH2Cl2 to give the aminodihalopropane complexes [(g5
-
C5R5)(CO)2Fe{NH2CH2CH(X)CH2X}]+ (R = H; X = Cl (5), Br (6) and
R = CH3; X = Br (7)) as shown in Scheme 2. The compounds
[5][BF4], [6][BF4] and [7][BF4] were obtained as microcrystalline
solids. The reaction of [4][BF4] with chlorine gave a mixture of
white and dark green sticky solids which showed no carbonyl
bands in the IR spectrum. There was no evidence to suggest the
Compound [7][BF4] is a product of the bromination reaction of
the allylamino compound [4][BF4]. The compound crystallizes in
ꢀ
P1 space group as brown plates from a 1:6 v/v solution of dichloro-
methane and diethyl ether. The asymmetric unit consists of one
cation and one anion. The structure shows an uncommon form of
disorder in which two enantiomorphs with 50% occupancy are
observed. Each molecular site is occupied with equal probability
with only the C(1)–C(2)(Br1)–C(3)(Br(2) arm of the molecule occu-
pying different sites. Fig. 5 shows molecular structures of the two
enantiomers R and S. Dibromoaminopropane coordinated to the
metal differently as gauche or anti depending on the enantioface
for this type of compound (in Scheme 3). In this compound, the
bromine atoms adopt a gauche-conformation in the (R) enantiomer
and an anti-conformation in the (S) enantiomer. The torsion angles
Br2A–C15A–C14A–Br1A and Br1B–C14B–C15B–Br2B in the two
formation of the halide complexes [(
cases.
g
5-C5R5)Fe(CO)2X] in all these
Halogenation is believed to proceed according to the mecha-
nism illustrated in Scheme 3. Initially, the halogen molecule is
polarized by pi bond electrons leading to the formation of haloni-
um and halide ions [41]. Then the halide adds to the side opposite
the carbon–halogen bond of the halonium ion in order to achieve
the maximum overlap of the C–X r⁄ antibonding molecular orbi-
tals. In this way the two halogens add in an anti-addition fashion

86
C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
R
R
+
R
R
X
+
R
R
R
R
Fe
CO
NH2
R
R
X2
OC
Fe
CO
NH2
OC
CH2Cl2
X
(5) R = H; X = Cl
(6) R = H; X = Br
(7) R = CH3; X = Br
(3) R = H
(4) R = CH3
Scheme 2. Halogenation of allylamino complexes.
Scheme 3. Proposed mechanism for bromination of complexes 3 and 4.
enantiomers are considerably different, 69.0(4)°and 178.8(3)°,
non equivalent binding sites are rare [42]. The reactions of the ally-
lamino complexes 3 and 4 with molar equivalents of the etherate
complexes 1 and 2 produced dinuclear complexes (Fig. 7) in which
the two iron systems are in different electronic environments.
Thus, the reaction of 3 with 1 and 2 in CH2Cl2 at room temperature
gave the dinuclear complexes 8 and 9, respectively. Similarly, 4 re-
acts with 1 and 2 to give the dinuclear complexes 10 and 11,
respectively. Complex 8 is insoluble in dichloromethane, hexane
and diethyl ether, but soluble in acetone, methanol, water and ace-
tonitrile. Thus it was easily isolated by filtration and purified by
recrystallization from an acetone/diethyl ether mixture (1/3 v/v).
Unlike 8, the other dinuclear complexes are very soluble in dichlo-
romethane and they were precipitated from their solution by addi-
tion of diethyl ether. The isolated compounds were characterized
by NMR, IR and elemental analysis and the characterization data
are given in Section 4.
respectively, and this is probably due to packing and steric effects
of the bulky {g
5-C5(CH3)5} and Br atoms. Coordination is via
the N atom resulting in ‘‘pseudo-octahedral three-legged piano
stool’’ structures. The Fe–N bond distances are both 2.036(3) Å
(Table 4), and are slightly longer than those observed in [4]
[BF4] [2.0294(14) Å], in [{
[2.022(15) Å] [31] and in [{{
g
5-C5(CH3)5}(CO)2Fe{NH2(CH2)3CH3}]BF4
g
5-C5(CH3)5}(CO)2Fe}2{
l-NH2(CH2)3-
NH2}](BF4)2 [2.0182(16) and 2.0202(14) Å] [31]. Similarly, C(2)–
C(3) is ca. 1.538 Å, significantly longer than the corresponding
bond in 4 (C(14)–C(15)) by ca. 0.216 Å. The bond angles C1–C2–C3,
C1–C2–Br1, Br1–C2–C3 and C2–C3–Br2 in both the enantiomers of
compound [7][BF4] are close to 109.5°, further confirming that the
allylamino complex 4 reacts with bromine to form a saturated
dibroaminoalkane complex.
In the crystal of [7][BF4] (Fig. 6), the cations and anions are con-
nected mainly through two C–HꢁꢁꢁF interaction and one N–HꢁꢁꢁF
interaction (Table 5). These interactions are further stabilized by
As expected, the infrared spectra of complexes 8 and 11 show
four absorption bands assignable to the terminal carbonyls. The
spectrum of complex 8 shows bands corresponding to the two car-
a
C–H. . .
p
intermolecular interaction [C(14)–H(14A)ꢁꢁꢁCg(1);
H(14A)ꢁꢁꢁCg = 2.61 and \C(14)–H(14A)ꢁꢁꢁCg(1) = 163°; symmetry
bonyls on the (
2078 and 2064 cmꢀ1 and another two bands assignable to the
two terminal carbonyls on the (
5-C5H5)(CO)2FeNH2CH2– side at
2041 and 2004 cmꢀ1. These data are in close agreement with those
of the related olefin complexes with the
5-C5H5)(CO)2-
g
5-C5H5)(CO)2FeCH2@CH– side of the molecule at
code = ꢀx, 1 ꢀ y, ꢀz].
g
2.3. Metallation of 3 and 4
(
g
Although a wide variety of bridged metal complexes are re-
ported, metal complexes bridged by ligands comprising of two
FeCH2@CH– moiety [6,9,11,12,43–45]. The infrared spectrum of
complex 11 shows two peaks assignable to the two terminal

C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
87
Fig. 5. Molecular structures of both enantiomers of [7][BF4] showing the numbering scheme of the atoms in (a) R and (b) S.
Table 4
Selected bond distances and bond angles in the two enantiomers of [7][BF4] (Å, °).
R
S
R
S
Cg. . .Fe(1)
Fe(1)–C(4)
Fe(1)–C(5)
Fe(1)–N(1)
C(4)–O(1)
C(5)–O(2)
C(1)–C(2)
C(2)–C(3)
C(2)–Br(1)
C(3)–Br(2)
N(1)–C(1)
1.727
1.727
Cg–Fe(1)–N(1)
Cg–Fe(1)–C(4)
Cg–Fe(1)–C(5)
Fe(1)–N(1)–C(1)
C(4)–Fe(1)–C(5)
C(4)–Fe(1)–N(1)
C(5)–Fe(1)–N(1)
C(2)–C(1)–N(1)
C(1)–C(2)–C(3)
C(1)–C(2)–Br(1)
C(2)–C(3)–Br(2)
125.6(5)
120.0(1)
122.1(8)
115.4(2)
96.56(13)
91.29(11)
93.23(13)
111.4(4)
115.4(5)
107.6(3)
113.7(4)
125.6(5)
120.0(1)
122.1(8)
121.8(3)
96.56(13)
91.29(11)
93.23(13)
116.4(5)
112.5(6)
109.0(5)
109.5(5)
1.794(3)
1.790(3)
2.036(2)
1.133(4)
1.137(4)
1.537(2)
1.537(2)
1.942(5)
1.923(6)
1.478(6)
1.794(3)
1.790(3)
2.36(2)
1.133(4)
1.137(4)
1.539(2)
1.539(2)
1.956(7)
1.967(7)
1.494(8)

88
C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
The 1H NMR data show that the allylamine molecule links the
two metal centers using the amine on one end and the vinyl
functionality on the other end. These two functionalities have
different electronic effects and as a result the 1H NMR spectra of
complexes 8 and 11 gave two well separated characteristic peaks
corresponding to protons of the two cyclopentadienyl ligands
and pentamethylcyclopentadienyl ligands in the different elec-
tronic environments. In the 1H NMR spectrum of 8, two peaks were
observed at 5.54 and 5.92 ppm and were assigned to the (
groups of the (
5-C5H5)(CO)2FeN and ( 5-C5H5)(CO)2FeC moieties,
respectively. The 1H NMR spectrum of complex 11 exhibited
peaks at 1.89 and 2.01 ppm corresponding to the {
5-C5(CH3)5}
group of the {
5-C5(CH3)5}(CO)2FeN– and { 5-C5(CH3)5}(CO)2FeC
moieties, respectively. The peaks corresponding to the (
5-C5H5)
and {
5-C5(CH3)5} ligands attached to the metal on the vinyl end
g
5-C5H5)
g
g
g
g
g
g
g
appear downfield relative to those on the amine end. The down-
field shift of these peaks upon olefin coordination has been previ-
ously attributed to the deshielding effects of the cationic metal
center [9]. However, the influence of
p-backdonation of electrons
Fig. 6. Packing diagram for [7][BF4] showing N–H. . .F and C–H. . .F intermolecular
interactions as viewed down the crystallographic c-axis.
from the metal orbital to the vinylic carbons should not be ignored,
since drawing of electrons from the metal increases its electrophi-
licity, which consequently would lead to deshielding of the
(
g
5-C5H5) or {
g
5-C5(CH3)5} protons. For this reason, whereas both
Table 5
metal centers are cationic, the (
g
5-C5H5) or { 5-C5(CH3)5} protons
g
Intermolecular interaction geometry for [7][BF4] (Å, °).
neighboring the metal on the vinyl end appear at higher chemical
D–H. . .A
D–H H. . .A D. . .A
D–H. . .A Symmetry
shift values than those on the amine side.
operator
The 1H NMR spectra of the mixed ligand complexes 9 and 10,
N(1)–H(1E). . .F(3)
C(2A)–H(2A). . .F(1)
C(12)–H(12C). . .F(4) 0.98 2.51
0.92 2.13
1.00 2.31
2.966(3) 150
3.134(2) 139
3.392(3) 150
ꢀx, ꢀy, 1 ꢀ z
which are structural isomers, show (
g
5-C5H5) peaks at 5.20 and
ꢀx, ꢀy, 1 ꢀ z
5.90 ppm, while {
g
5-C5(CH3)5} peaks were observed at 2.01 and
ꢀx, 1 ꢀ y, 1 ꢀ z
1.90 ppm, respectively. Complexes 8 and 10 show characteristic
sharp doublets at ca. 4.14 ppm (J ꢃ 8.3 Hz) and 3.62 ppm
(J ꢃ 14.24 Hz) assignable to the diastereotopic methylene protons
carbonyls on the {g
5-C5(CH3)5}(CO)2FeCH2@CH– side at 2050 and
2014 cmꢀ1, which is in agreement with the reported data for re-
lated complexes [44,46]. The other two bands assignable to the
c
to NH2 which are cis and trans to bCH. These values are in good
agreement with data reported for related cyclopentadienyliron
complexes [6,9,11,12,44,45]. Similar sharp doublets were observed
in the 1H NMR spectra of complexes 9 and 11 at ca. 3.01
(J ꢃ 7.76 Hz) and 3.55 (J ꢃ 13.84 Hz), also in agreement with data
reported for the related pentamethylcyclopentadienyl complexes
two terminal carbonyls on the {g
5-C5(CH3)5}(CO)2FeNH2CH2– side
were observed at 1986 and 1955 cmꢀ1. These values are at consid-
erably lower wavenumbers than the ca. 2023 and 1970 cmꢀ1 found
for the compound [{g
5-C5(CH3)5}(CO)2Fe{NH2(CH2)3CH3}]BF4 [31].
The infrared spectrum of complex 9 shows only two bands,
while that of 10 shows three bands corresponding to the two sets
of terminal carbonyls. The carbonyl bands of complexes 9 and 10
are strong and broad suggesting band overlap. All IR spectra of
complexes 8–11 show two bands in the N–H stretching region at
ca. 3308 and 3268 cmꢀ1, which are assignable to NH asymmetric
and symꢀm1etric stretching, respectively. The medium band at ca.
1640 cmꢀ1, as well as the peaks at ca. 938 cmꢀ1, which were as-
signed to C@C stretching and @CH wagging in the infrared spectra
of the parent allylamino complexes, are absent.
[44,46]. The aCH2 protons are also diastereotopic, hence two sep-
arate multiplets assignable to these protons were observed at ca.
2.35 and 3.44 ppm. These observations confirm that complexes
8–11 have a rigid chiral structure which is maintained even in
solution. The 13C NMR spectra of complexes 8–11 show peaks
assignable to the carbon of the vinyl group coordinated to the
metal at chemical shifts below 80 ppm. This is about 59 ppm
upfield relative to the pendant vinyl groups in the starting materi-
als (complexes 3 and 4). This is a clear indication that the vinyl
1600 cm
can be assigned to NH bending. The peak at ca.
group of allylamino ligand links the second metal center in a g2
-
fashion.
Fig. 7. The dinuclear complexes, [(g .
5-C5R5)(CO)2Fe(NH2CH2CH@CH2)Fe(CO)2(g5-C5R05)]2+

C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
89
2.4. Reaction of [{(
[8][BF4]2 with NaI
g
5-C5H5)(CO)2Fe}2(
l
-NH2CH2CH@CH2)](BF4)2,
CH2Cl2 was distilled from phosphorus(V) oxide and used immedi-
ately. Dry chlorine gas was generated according to literature
method [49]. The other reagents were used as received from
the suppliers without further purification. Melting points were
recorded on an Ernst Leitz Wetzlar hot-stage microscope and
are uncorrected. Elemental analyses were performed on a LECO
CHNS-932 elemental analyzer. Infrared spectra were recorded
using an ATR PerkinElmer Spectrum 100 spectrophotometer
It is well established that olefin complexes are demetallated
when treated with excess NaI to give [(
5-C5H5)Fe(CO)2I] and the
corresponding olefin [12,45,47]. Haloalkene displacement when
olefin complexes are treated with NaI or Na[(
5-C5H5)Fe(CO)2]
has also been reported [19]. Contrary to these observations, the
dinuclear salt [8][BF4]2 reacts with NaI at room temperature in ace-
g
g
between 4000 and 400 cmꢀ1 1H and 13C NMR spectra were re-
.
tone to give the mononuclear compound [(
Fe(NH2CH2CH@CH2)]I (12) and the known neutral iodo complex
[(
5-C5H5)Fe(CO)2I] [48] according to Eq. (1). There was no evi-
dence of the formation of the dimeric complex [(
5-C5H5)Fe(CO)2]2
g
5-C5H5)(CO)2-
corded using Bruker 400 MHz and 600 MHz spectrometers and
chemical shifts are recorded in ppm. Correlations were confirmed
through COSY and HSQC experiments. The deuterated solvents
CDCl3 (Aldrich, 99.8%), acetonitrile-d3 (Merck, 99%), acetone-d6
(Aldrich, 99.5%) and methanol-d4 (Aldrich, 99.8%) were used as
g
g
nor of Fe–N bond cleavage, even when the reaction was repeated at
35 °C. Compound 12 was obtained as a yellow microcrystalline so-
lid upon treating the dichloromethane extract with diethyl ether.
The iodo complex remained in the mother liquor and it was ob-
tained as a gray crystalline solid upon evaporation.
purchased. The precursors [(
[{
5-C5(CH3)5}(CO)2Fe(THF)]BF4 [50] were prepared by the litera-
ture methods.
g
5-C5H5)(CO)2Fe(OEt2)]BF4 [29] and
g
4.2. Reaction of allylamine with one equivalent of [(g5
C5H5)(CO)2Fe(OEt2)]BF4, [1][BF4]
-
Into a solution of compound [1][BF4] (0.86 g, 2.54 mmol) in
CH2Cl2 (10 ml), allylamine (0.19 ml) was added and the mixture
stirred for 6 h under nitrogen at room temperature, after which a
yellow precipitate was formed. The mixture was filtered into the
pre-weighed Schlenk tube and the residue washed with a mini-
mum amount of dichloromethane (2 ml) followed by diethyl ether
(5 ml). A further crop of the compound was recovered from the fil-
trate by addition of diethyl ether and allowing the mixture to stand
at room temperature for 1 h. The mother liquor was syringed off
and the residue was washed with diethyl ether to give the yellow
The formation of complex 12 illustrates that the Fe–N bond in
the allylamino complex is too strong to be cleaved by the iodide,
Iꢀ. The complex was characterized by elemental analysis, IR and
NMR spectroscopy and the data are listed in Section 4ꢀ.7. A similar
pattern of the IR peaks was observed as for the BF4 salt, com-
pound [3][BF4], with the exception of the peaks at 999–
1051 cmꢀ1 (assigned to BF4ꢀ) and the finger-print region.
microcrystalline solid of [(g
5-C5H5)(CO)2Fe(NH2CH2CH@CH2)]BF4,
[3][BF4]. Yield 0.80 g, 98%. Anal. Calc. for C10H12BF4FeNO2: C,
37.38; H, 3.74; N, 4.36. Found: C, 37.86; H, 3.84; N, 3.99%. 1H
NMR (600 MHz, methanol-d4) 5.36 (s, 5H,
g
5-C5H5), 3.81 (s, 2H,
NH2), 2.95 (q, JHH = 6.60 Hz, 2H, –CH2), 5.80 (m, 1H, @CH), 5.22
(d, JHH = 10.38 Hz, 1H, @CH cis), 5.26 (d, JHH = 17.22 Hz, 1H, @CH
trans). 13C NMR (600 MHz, methanol-d4): 85.95 ( 5-C5H5), 53.88
g
3. Conclusion
(–CH2), 134.99 (CH@), 117.81 (@CH2), 211.05 (CO). IR (solid state)
vmax (cmꢀ1): 2051, 2004 (CO); 3307, 3277 (NH2). Decomposes at
temperature >120 °C.
We have unequivocally shown that the etherate complexes
[(
with 3-aminoprop-1-ene to give the new allylamino complexes
of the type [(
5-C5R5)(CO)2Fe(NH2CH2CH@CH2)]+, which in
turn undergo electrophilic halogenation to form new chiral
complexes of the type [(
5-C5R5)(CO)2Fe{NH2CH2CH(X)CH2X}]+.
The crystallographic data of compound [{
5-C5(CH3)5}(CO)2-
g g
5-C5H5)(CO)2Fe(OEt2)]+ and [{ 5-C5(CH3)5}Fe(CO)2(THF)]+ react
g
4.3. Reaction of [(
with chlorine
g
5-C5H5)(CO)2Fe(NH2CH2CH@CH2)]BF4, [3][BF4]
g
g
Fe{NH2CH2CH(Br)CH2Br}]BF4 show that it exists as a mixture of
(R) and (S) enantiomers. The reactions of the etherate complexes
with the allylamino complexes is a convenient route to dinuclear
A Schlenk tube equipped with a magnetic bar and charged with
a solution of [3][BF4] (0.16 g, 0.498 mmol) in CH2Cl2 (10 ml) was
cooled to ꢀ78 °C (dry ice/acetone) and then chlorine gas con-
densed into the mixture. The mixture was stirred and allowed to
warm slowly to room temperature for the excess chlorine gas to
escape and then it was filtered into a pre-weighed Schlenk tube.
Diethyl ether (25 ml) was added and the mixture was allowed to
stand overnight, after which a yellow microcrystalline solid was
found stuck on the walls of the Schlenk tube. The mother liquor
was syringed off and the residue washed with diethyl ether
(5 ml) and dried under reduced pressure gave 0.083 g (47%) of
compound [5][BF4]. Anal. Calc. for C10H12BCl2F4FeNO2: C, 30.66;
H, 3.09; N, 3.58. Found: C, 30.82; H, 3.46; N, 3.09%. 1H NMR
complexes of the type [{
g
5-C5R5(CO)2Fe(NH2CH2CH@CH2)Fe(-
2+
CO)2(g5-C5R5 )] in which the two metal fragments are bridged
by the allylamine via the amine on one side and via the vinyl group
on the other side. Coordination of the vinyl group occurs only after
amine coordination, as expected.
0
4. Experimental
4.1. General
All experimental manipulations of organometallic compounds
were carried out under inert atmosphere using standard Schlenk
line procedures unless otherwise stated. Reagent grade THF, hex-
ane and Et2O were distilled from sodium/benzophenone and used
immediately; acetone and MeCN were distilled from anhydrous
CaCl2 and stored under molecular sieves of porosity size 4;
(400 MHz, methanol-d4) 5.39 (s, 5H,
3.85 (br, 2H, NH2), 3.82 (br, 2H, CH2Cl), 2.87 (br, 1H, CH2–N), 2.70
(br, 1H, CH2–N). 13C NMR (400 MHz, methanol-d4): 87.63 (g5
g
5-C5H5), 4.14 (br, 1H, CHCl),
-
C5H5), 62.18 (CHCl), 56.71 (CH2-N), 46.87 (CH2Cl), 212.06 (CO). IR
(solid-state) vmax (cmꢀ1): 2052, 2001 (CO); 3306, 3274 (NH2).
M.p., 63–65 °C.

90
C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
4.4. Reaction of compound [3][BF4] with bromine
4.7. Reaction of [{(g l-NH2CH2CHCH2)](BF4)2,
5-C5H5)(CO)2Fe}2(
[8][BF4]2, with NaI
Liquid bromine (0.2 ml, 3.882 mmol) was added to a solution of
compound [3][BF4] (0.24 g, 0.732 mmol) in CH2Cl2 (20 ml) and the
mixture stirred under nitrogen for 2 h at room temperature. Excess
bromine was removed under vacuum and the mixture evaporated
to ca. 7 ml under reduced pressure. Diethyl ether was added until a
yellow precipitate was formed and then the mixture was allowed
to stand at room temperature for 5 h in the dark. The mother liquor
was removed and the yellow residue was washed with
diethyl ether (2 ꢂ 10 ml). Drying the residue under reduced
To an acetone solution (25 ml) of compound [8][BF4]2 (0.33 g,
0.564 mmol) was added NaI (1.02 g, 6.80 mmol). The solution
was stirred at 35 °C for 12 h, during which the solution turned from
yellow to dark brown. The solvent was removed under reduced
pressure and the residue extracted with dichloromethane
(30 ml). The extract was then concentrated to about one third of
the initial volume. Addition of diethyl ether completed the precip-
itation of the allylamino complex [(g
5-C5H5)(CO)2Fe(NH2CH2CH@-
pressure gave 0.197 g (56% yield) of microcrystalline [(g5
-
CH2)]I, 12, which was filtered off, washed with diethyl ether
(2 ꢂ 10 ml) and dried under reduced pressure. It was purified fur-
ther by recrystallization from acetone/diethyl ether 1:4 v/v. to give
a bright yellow microcrystalline solid (0.114 g, 56%). Anal. Calc. for
C5H5)(CO)2{NH2CH2CH(Br)CH2Br}]BF4, [6][BF4]. Anal. Calc. for
C10H12BBr2F4FeNO2: C, 24.99; H, 2.52; N, 2.91. Found: C, 25.06;
H, 2.27; N, 2.83%. 1H NMR (400 MHz, methanol-d4) 5.40 (s, 5H,
g
5-C5H5), 4.22 (m, 1H, CHBr), 3.88 (m, 1H, CH2Br), 3.77 (m, 1H,
C
10H12FeINO2: C, 33.27; H, 3.35; N, 3.88. Found: C, 33.35; H, 3.54;
CH2–N), 3.00 (m, 1H, CH2–N), 2.79 (m, 1H, CH2). NH not observed.
N, 3.76%. 1H NMR (600 MHz, acetone-d6) 5.62 (s, 5H, 5-C5H5), 4.14
g
13C NMR (400 MHz, methanol-d4): 87.42 ( 5-C5H5), 57.67 (CH2–N),
g
(s, 2H, NH2), 3.09 (q, JHH = 6.18 Hz, 2H, –CH2), 6.01 (m, 1H, @CH),
52.85 (CHBr), 34.18 (CH2Br), 212.04 (CO). IR (solid state) vmax
5.15 (d, JHH = 10.02 Hz, 1H, @CH cis), 5.28 (d, JHH = 17.16 Hz, 1H,
(cmꢀ1): 2047, 1995 (CO); 3294, 3266 (NH2). M.p., 109–110 °C.
@CH trans). 13C NMR (600 MHz, acetone-d6): 86.54 ( 5-C5H5),
g
53.85 (–CH2), 135.77 (CH@), 118.02 (@CH2), 211.73 (CO). IR (solid
state) vmax (cmꢀ1): 2042, 2002 (CO); 3152 br (NH2). M.p., 130–
131 °C.
4.5. Reaction of compound [3][BF4] with compound [1][BF4]
The filtrate was evaporated to dryness to give a purple gray
A mixture of compound [1][BF4] (0.15 g, 0.440 mmol) in CH2Cl2
(10 ml) and that of compound [3][BF4] (0.10 g, 0.31 mmol) in
CH2Cl2 (15 ml) was stirred at room temperature for 1 h. An orange
solid formed and was allowed to settle for 30 min after which the
mother liquor was syringed off. The residue was washed with
CH2Cl2 (2 ꢂ 5 ml) and dried under reduced pressure. The product
was further purified by recrystallizing from acetone/diethyl ether
microcrystalline solid (0.53 g; 31% yield) which according to IR
and NMR was found to be the known [(g
5-C5H5)(CO)2FeI] [51].
4.8. Reaction of allylamine with one equivalent of [{g5
C5(CH3)5}Fe(CO)2(THF)]BF4, [2][BF4]
-
3-Amino-1-propene (0.039 ml, 0.523 mmol), was added to a
solution of compound [2][BF4] (0.21 g, 0.517 mmol) in CH2Cl2
(10 ml) and the mixture stirred at room temperature for 12 h.
The mixture was filtered into a pre-weighed Schlenk tube and
diethyl ether added to the filtrate. The mixture was allowed to
stand in the dark at room temperature for 18 h after which yel-
low-brown crystals stuck on the walls of the Schlenk tube. The
mother liquor was syringed off and the crystals washed with
diethyl ether (2 ꢂ 5 ml) after which it was dried under reduced
pressure to give 0.158 g (78%) of compound [4][BF4]. Anal. Calc.
for C15H22BF4FeNO2: C, 46.08; H, 5.67; N, 3.58. Found: C, 45.93;
H, 6.03; N, 3.39%. 1H NMR (400 MHz, acetone-d4) 1.93 (s, 15H,
(1/3 v/v) to give a bright yellow microcrystalline solid, [{(g5
-
C5H5)(CO)2Fe}2(NH2CH2CH@CH2)](BF4)2, [8][BF4]2. Yield. 0.130 g,
72%. Anal. Calc. for C17H17B2F8FeNO2: C, 34.93; H, 2.93; N, 2.40.
Found: C, 34.84; H, 3.40; N, 1.87%. 1H NMR (400 MHz, acetone-
d6) 5.92 (s, 5H,
g g
5-C5H5), 5.54 (s, 5H, 5-C5H5), 4.99 (m, 1H, CH),
4.12 (d, JHH = 8.32 Hz, 1H, cis CH), 3.72 (d, JHH = 14.20 Hz, 1H, trans
CH), 3.57 (m, 1H, CH–N), 2.48 (m, 1H, CH–N), 3.76 (s br, 2H, NH2).
13C NMR (400 MHz, acetone-d6): 90.94 ( 5-C5H5), 87.46 ( 5-C5H5),
g g
76.96 (CH), 57.42 (CH2-Fe), 56.70 (CH2-N), 211.81, 211.75, 210.59,
207.87 (CO). IR (solid state) vmax (cmꢀ1): 2078, 2064, 2041, 2004
(CO); 3309, 3270 (NH2). Decomposes at temperature >129°C.
g
5-C5(CH3)5), 3.23 (br, 2H, NH2), 3.08 (q, JHH = 6.80 Hz, 2H, –CH2),
5.84 (m, 1H, @CH), 5.21 (d, 1H, JHH = 17.17 Hz, @CH2), 5.15 (d,
4.6. Reaction of compound [3][BF4] with [{g5
C5(CH3)5}Fe(CO)2(THF)]BF4, [2][BF4]
-
1H, JHH = 10.33 Hz, @CH2). 13C NMR (400 MHz, acetone-d6): 9.26
(g (g
5-C5H5), 98.71 5-C5(CH3)5), 55.10 (–CH2), 136.57 (CH@),
118.86 (@CH2), 214.42 (CO). IR (solid state) vmax (cmꢀ1): 2029,
1983 (CO); 3212, 3280 (NH2). M.p., 131–132 °C.
To a stirred solution of compound [3][BF4] (0.15 g, 0.467 mmol)
in CH2Cl2 (10 ml), a solution of [2][BF4] (0.19 g; 0.468 mmol) in
CH2Cl2 (10 ml) was added within 30 s. The mixture was stirred
for 12 h after which it was filtered into a pre-weighed Schlenk tube
and diethyl ether added to the filtrate to give a yellow precipitate.
The precipitate was allowed to stand undisturbed for 5 h and then
the mother liquor was removed. Washing the residue with diethyl
ether (10 ml) and drying it under reduced pressure afforded
4.9. Reaction of [{
with bromine
g
5-C5(CH3)5}(CO)2Fe(NH2CH2CH@CH2)]BF4, [4][BF4]
To a solution of compound [4][BF4] (0.21 g, 0.537 mmol) in
CH2Cl2 (10 ml), bromine (0.05 ml, 1.048 mmol) was added and
the mixture stirred for 5 h. The solvent was removed resulting in
a yellow solid which was recrystallized from dichloromethane/
diethyl ether (1:6 v/v) to give an orange microcrystalline solid of
0.128 g (42% yield) of the dinuclear mixed ligand complex [(g5
-
C5H5)(CO)2Fe(NH2CH2CHCH2)Fe(CO)2{
g
5-C5(CH3)5}](BF4)2,
[9][BF4]2. Anal. Calc. for C22H27B2F8Fe2NO4: C, 40.36; H, 4.16; N,
[{g
5-C5(CH3)5}(CO)2Fe{NH2CH2CH(Br)CH2Br}]BF4, [7][BF4]. Yield,
2.14. Found: C, 40.46; H, 3.89; N, 2.16%. 1H NMR (400 MHz, ace-
0.145 g, 49%. Anal. Calc. for C15H22BF4Br2FeNO2: C, 32.71; H, 4.03;
N, 2.54. Found: C, 32.41; H, 4.06; N, 2.23%. 1H NMR (400 MHz,
acetone-d6) 4.47 (m, 1H, CHBr), 3.94 (m, 2H, CH2Br), 3.15 (m, 1H,
tone-d6) 5.20 (s, 5H, (
cis CH), 2.85 (br, 1H, trans CH), 3.40 (m, 1H, CH–N), 2.35 (m, 1H,
CH–N), 2.01 (s, 15H,
5-C5(CH3)5). 13C NMR (400 MHz, acetone-
d6): 87.49 (
5-C5H5), 77.50 (CH), 60.42 (CH2–Fe), 56.95 (CH2–N),
9.16 (
g
5-C5H5)), 3.71 (m, 1H, CH), 3.54 (br, 1H,
g
CH–N), 2.83 (m, 1H, CH–N), 3.34 (br, 2H, NH2), 1.97 (s, 15H, g5
-
g
C5(CH3)5). 13C NMR (400 MHz, acetone-d6): 54.31 (CHBr), 57.07
g
5-C5(CH3)5), 103.85 (
g
5-C5(CH3)5), 213.13, 212.38, 211.88,
(CH2N), 35.16 (CH2Br), 9.47 (g g
5-C5(CH3)5), 98.83 ( 5-C5(CH3)5),
211.82 (CO). IR (solid state) vmax (cmꢀ1): 2053, 2001br (CO);
3304, 3272 (NH). M.p., 40–42 °C.
213.87, 213.70 (CO). IR (solid state) vmax (cmꢀ1): 2034, 1978
(CO); 3296, 3268 (NH). M.p., 111–112 °C.

C.M. M’thiruaine et al. / Polyhedron 40 (2012) 81–92
91
4.10. Reaction of compound [4][BF4] with compound [1][BF4]
Witwatersrand, South Africa) and Dr. Vincent Smith (Stellenbosch
University, South Africa) with the X-ray data collection is highly
appreciated.
To a solution of compound [4][BF4] (0.12 g, 0.307 mmol) in
CH2Cl2 (10 ml), a solution of [1][BF4] (0.11 g, 0.325 mmol) was
added and the mixture stirred overnight. The mixture was filtered
and diethyl ether was added into the filtrate to form an orange sus-
pension. The mixture was kept at 0° for 8 h after which it was fil-
tered and the residue washed with diethyl ether (2 ꢂ 5 ml) to give
an orange-yellow solid. This was dissolved in a minimum of dichlo-
romethane and precipitated using diethyl ether and then filtered.
This process was repeated three times to give the pure mixed-li-
Appendix A. Supplementary data
CCDC 851117, 851115 and 851116 contains the supplementary
crystallographic data for compounds [3][BF4], [4][BF4] and [7][BF4],
respectively. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
gand compound [{g -
5-C5(CH3)5}(CO)2Fe(NH2CH2CHCH2)Fe(g5
C5H5)(CO)2](BF4)2, [10][BF4]. Yield 0.091 g, 45%. Anal. Calc. for
C22H27B2F8Fe2NO4: C, 40.36; H, 4.16; N, 2.14. Found: C, 40.26; H,
4.19; N, 2.13%. 1H NMR (400 MHz, acetone-d6) 5.90 (s, 5H, g5
-
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4.11. Reaction of compound [4][BF4] with compound [2][BF4]
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CH2Cl2 (10 ml),
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0.051 mmol) in CH2Cl2 (10 ml) was added. The mixture was stirred
at room temperature for 16 h after which diethyl ether was added
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for 20 min and the mother liquor was removed. The residue was
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Fe}2( -NH2CH2CHCH2)](BF4)2, [11][BF4]. Yield 51%. Anal. Calc. for
g
5-C5(CH3)5}(CO)2-
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C
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CH), 3.55 (d, JHH = 13.85 Hz, 1H, trans CH), 3.18 (d, JHH = 7.76 Hz,
1H, cisCH), 3.28 (m, 1H, CH–N), 2.24 (m, 1H, CH–N), 2.01 (s, Cp⁄–
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g
5-C5(CH3)5), 9.27
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Crystals of compounds [3][BF4], [4][BF4] and [7][BF4] suitable
for single crystal X-ray diffraction were obtained by the liquid dif-
fusion method of crystal growth. A nitrogen-saturated solution of
each compound in dichloromethane was layered with diethyl ether
and kept in the dark at room temperature for a period of one week.
The X-ray diffraction data of [3][BF4] and [4][BF4] were collected on
a Bruker Apex-II CCD area detector diffractometer with graphite
monochromated Mo K
[52] data collection software, while that of [7][BF4] was collected
on SMART APEX CCD diffractometer, also using Mo K radiation.
The structures were solved and refined using SHELXS-97 and SHELXL
97 [53] while molecular graphics were generated using OLEX
a radiation (50 kV, 30 mA) using the APEX2
a
-
2
[54]. The crystallographic data and structural refinement informa-
tion for compounds [3][BF4], [4][BF4] and [7][BF4] are summarized
in Table 2.
Acknowledgments
We sincerely thank the NRF, THRIP and UKZN (URF) for financial
support. The assistance of Dr. Manuel Fernandes (University of

92
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