Formation of phosphorus heterocycles using a cationic electrophilic phosphinidene complex

Article abstract of DOI:10.1016/j.jorganchem.2013.07.076

The electrophilic terminal aminophosphinidene complex [CpFe(CO) ₂P{N-i-Pr₂}][X] (Cp = cyclopentadienyl, i-Pr = isopropyl, X = AlCl₄ or NaBPh₄), generated from [CpFe(CO) ₂{P(Cl)N-i-Pr₂}] by chloride abstraction, reacts with alkynes and alkenes via (1 + 2) cycloaddition to form phosphirenes and phosphiranes respectively. Conjugated alkenes react with [CpFe(CO) ₂P{N-i-Pr₂}]⁺ to form phosphirane intermediates, which then rearrange to 3-phospholenes. The phosphinidene complex reacts with benzylideneacetone to give an oxo-3-phospholene complex. Azobenzene reacts with [CpFe(CO)₂P{N-i-Pr₂}]⁺ to form a benzodiazophosphole via C-H activation. Addition of HCl or HBF ₄·Et₂O to the iron diphenylphosphirene complex and iron benzodiazophosphole complex results in P-N bond cleavage, yielding the respective chlorophosphorus heterocyclic complexes. The heterocycles can be removed from the metal complexes to make metal free phosphorus heterocycles by addition of trimethyl- or triethylphosphine.

Full text of DOI:10.1016/j.jorganchem.2013.07.076

Journal of Organometallic Chemistry 745-746 (2013) 347e355
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Formation of phosphorus heterocycles using a cationic electrophilic
phosphinidene complex
*
Kandasamy Vaheesar, Colin M. Kuntz, Brian T. Sterenberg
Department of Chemistry and Biochemistry, University of Regina, 3737 Wascana Parkway, Regina, Saskatchewan, Canada S4S 0A2
a r t i c l e i n f o
a b s t r a c t
Article history:
The electrophilic terminal aminophosphinidene complex [CpFe(CO)2P{N-i-Pr2}][X] (Cp ¼ cyclopentadienyl,
i-Pr ¼ isopropyl, X ¼ AlCl4 or NaBPh4), generated from [CpFe(CO)2{P(Cl)N-i-Pr2}] by chloride abstraction,
reacts with alkynes and alkenes via (1 þ 2) cycloaddition to form phosphirenes and phosphiranes
respectively. Conjugated alkenes react with [CpFe(CO)2P{N-i-Pr2}]þ to form phosphirane intermediates,
which then rearrange to 3-phospholenes. The phosphinidene complex reacts with benzylideneacetone to
give an oxo-3-phospholene complex. Azobenzene reacts with [CpFe(CO)2P{N-i-Pr2}]þ to form a benzo-
diazophosphole via CeH activation. Addition of HCl or HBF4$Et2O to the iron diphenylphosphirene complex
and iron benzodiazophosphole complex results in PeN bond cleavage, yielding the respective chlor-
ophosphorus heterocyclic complexes. The heterocycles can be removed from the metal complexes to make
metal free phosphorus heterocycles by addition of trimethyl- or triethylphosphine.
Received 20 June 2013
Received in revised form
24 July 2013
Accepted 30 July 2013
Keywords:
Phosphinidene
Cycloaddition
Phosphorus heterocycle
Metal-mediated synthesis
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
We were interested in carrying out a more comprehensive study
of cycloaddition reactions of a stable, cationic phosphinidene
Transition metal terminal phosphinidene complexes can be
considered analogous to metal carbene complexes, and like car-
benes, their reactivity ranges from nucleophilic to electrophilic
extremes [1e3]. The first electrophilic terminal complexes were
the transient species [W(CO)5PR], generated in situ by thermal
decomposition of precursor 7-phosphanorbornadiene complexes
[4]. Their reactivity has been well studied using trapping reactions
with a variety of reagents [5e7]. These trapping reactions, in
conjunction with computational studies [1,2,8e11], provide a
clear understanding of the chemistry of transient electrophilic
phosphinidene complexes. Their characteristic reactions include
bond activation, nucleophilic addition, and cycloaddition re-
actions to form P-heterocycles. Stable electrophilic terminal
phosphinidene complexes of molybdenum and tungsten were
first reported in 2001 [12]. Since then a wide range of stable
electrophilic terminal phosphinidene complexes have been syn-
thesized [13e16]. The reactivity of stable, cationic phosphinidene
complexes has not been as well studied as that of the neutral
transient species, but examples of nucleophilic addition [17], bond
activation [18], and cycloaddition reactions [13,16] have been
described.
complex. The first objective was to see if the typical reactivity of
these complexes differs in any significant way from that of the
neutral, transient complexes. The second goal was to see if these
reactions can be developed into a useful synthetic route to func-
tional P heterocycles for synthetic applications such as ligand
synthesis. With the second goal in mind, we chose [CpFe(CO)2{PN-
i-Pr2}]þ [15] as our metal complex, because it is relatively easy to
synthesis and inexpensive enough to be useful for stoichiometric
synthesis, and because i-Pr2N group is potentially cleavable,
providing a route to further functionalization.
2. Results and discussion
2.1. Cycloaddition reactions
The electrophilic terminal aminophosphinidene complex
[CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) is readily formed by abstraction
of chloride from the chloroaminophosphido complex [CpFe(-
CO)2{P(Cl)N-i-Pr2}] (1) using AlCl3. The chloride can also be
abstracted from 1 using NaBPh4, leading to [CpFe(CO)2{PN-i-Pr2}]
[BPh4] (2b), giving us a choice of counterion. Reactions of 2 can be
carried out either with isolated aminophosphinidene complex or in
situ. Because the aminophosphinidene is very sensitive, we typi-
cally generate it in situ and react it with a substrate without
isolating it.
* Corresponding author. Tel.: þ1 306 585 4106.
E-mail address: brian.sterenberg@uregina.ca (B.T. Sterenberg).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.07.076

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K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
Scheme 2.
Scheme 1.
of 4 in CD2Cl2, which resulted in the formation of a solution con-
taining both 2 and 4. Addition of excess styrene drives the equi-
librium toward 4.
Reaction of the aminophosphinidene complex 2 with dipheny-
lacetylene results in a (1 þ 2) cycloaddition, leading to the ami-
nophosphirene complex 3 (Scheme 1). The 31P NMR spectrum of 3
Reaction of 2 with isoprene (2-methyl-1,3-butadiene) led to the
2-phospholene complex 6. The 1H NMR spectrum of 6 shows the
shows a characteristic high field shift at
d
ꢀ69.7. High field chemical
shifts in 31P NMR spectrum are characteristic of phosphorus in
three-membered rings [19e21]. The infrared spectrum shows
carbonyl ꢀstretching frequencies at 2059 and 2016 cmꢀ1. Complex
3b (BPh4 counterion) has been structurally characterized (Fig. 1).
The cation consists of CpFe(CO)2 fragment coordinated by an ami-
nophosphirene ring. The di-isopropylamino group is oriented away
expected resonances for the 3-phospholene alkenyl (
d 3.98),
methylene ( 3.38 and 2.81), and methyl ( 1.86) protons. Direct
d
d
monitoring of the reaction solution immediately after addition of
isoprene revealed the presence of two additional intermediates
that eventually convert to 6. If the reaction is carried out at 0 ꢁC, the
intermediates can be formed as the major components. The 31P
ꢀ
from the Cp ring. The PeN bond distance is 1.672(2) A, which is
chemical shifts of
d
ꢀ49.7 and ꢀ51.9 are consistent with their
consistent with a nitrogenephosphorus single bond. Bond dis-
tances and angles within the three-membered ring are consistent
with those of previously characterized phosphirenes [4,13,22,23].
Compound2 reactswithstyrenetoformthephosphiranecomplex
[CpFe(CO)2{P(N-i-Pr2)CH(Ph)CH2}][AlCl4] (4a, b) (Scheme 2). How-
ever, 2 does not react with the more sterically crowded stilbene, even
formulation as vinylphosphiranes 5a and 5b (26:1), indicating
that 6 is formed via (1 þ 2) addition followed by ring expansion
(Scheme 3).
Because the isoprene product 6 was persistently non-crystalline,
compound 2 was also reacted with 1,4-diphenyl-1,3-butadiene to
form the analogous 3-phospholene complex 7 (Scheme 3). In this
case the reaction is much slower, requiring 8 h at 60 ꢁC. Because of
the higher temperatures, no phosphirane intermediates could be
detected. This reactivity contrasts with that of the neutral transient
phosphinidene [W(CO)5PPh], which reacts with 1,4-diphenyl-1,3-
butadiene to form a vinylphosphirane, but does not give the cor-
responding phospholene complex [24]. The steric size of the metal
complex may be controlling regioselectivity, in that the smaller
CpFe(CO)2 fragment allows a rearrangement to the 3-phospholene,
which the larger W(CO)5 fragment prevents. Compound 7 has been
structurally characterized (Fig. 3). The cation consists of CpFe(CO)2
fragment coordinated by a phospholene ring. The phospholene ring
is a planar. The phenyl groups and the CpFe(CO)2 fragment are
at 100 ꢁC. The 31P NMR spectrum of 4 shows two peaks at
d
ꢀ52.0
(81%) and ꢀ53.8 (19%) that result from two diastereoisomers. Com-
pound 4a has been structurally characterized and an ORTEP diagram
is shown in Fig. 2. In the diastereomer crystallized, the CpFe(CO)2
fragment and the phenyl group are on the same side of PC2 ring and
the amino group is on the opposite side. The Ph group is presumably
on the opposite side to the CpFe(CO)2 fragment in the other
diastereomer.
The styrene in 4 can be readily displaced by an alkyne to form
aminophosphirene 3, showing that the phosphinidene has a
greater affinity for alkynes than alkenes. This reaction also suggests
that 4 is in equilibrium with its components, phosphinidene and
styrene. This equilibrium was confirmed by dissolution of crystals
Fe1
C8
Fe
P1
C9
P
C9
N1
C8
N
Fig. 1. ORTEP diagram showing the structure of [CpFe(CO)2{P(N-i-Pr2)C(Ph)C(Ph)}]
[BPh4] (3b). Thermal ellipsoids are shown at the 50% level. Hydrogen atoms and the
BPh4 counterion have been omitted. Selected distances (A) and angles (deg): Fee
P ¼ 2.2368(7), PeN ¼ 1.672(2), PeC8 ¼ 1.780(2), PeC9 ¼ 1.780(2), C8eC9 ¼ 1.332(3),
C8ePeC9 ¼ 43.9(1), PeC8eC9 ¼ 68.0(1), PeC9eC8 ¼ 68.0(1).
Fig. 2. ORTEP diagram showing the structure of [CpFe(CO)2{P(N-i-Pr2)CH(Ph)CH2}]
[AlCl4] (4a). Thermal ellipsoids are shown at the 50% level. Hydrogen atoms and the
AlCl4 counterion have been omitted. Selected distances (A) and angles (deg): Fee
P ¼ 2.2272(6), PeN ¼ 1.649(2), PeC8 ¼ 1.800(2), PeC9 ¼ 1.850(2), C9ePeC8 ¼ 49.3(1),
PeC9eC8 ¼ 67.1(1), PeC8eC9 ¼ 63.7(1).
ꢀ
ꢀ
ꢀ
ꢀ

K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
349
Fe1
C10
C8
P1
C9
O3
N1
Fig. 4. ORTEP diagram showing the structuꢀre of 8. Thermal ellipsoids are shown at the
50% level. Hydrogen atoms and the AlCl4 counterion have been omitted. Selected
ꢀ
distances (A) and angles (deg): FeeP ¼ 2.2129(5), PeN ¼ 1.643(1), PeO3 ¼ 1.650(1), Pe
C10 ¼ 1.883(1), O3eC8 ¼ 1.400(2), C10eC9 ¼ 1.505(2), C9eC8 ¼ 1.320(3), C10ePe
O3 ¼ 94.41(7), PeO3eC8 ¼ 112.3(1), O3eC8eC9 ¼ 116.1(1), C8eC9eC10 ¼ 116.1(2),
C9eC10eP ¼ 101.1(1).
Scheme 3.
directed to one face of the ring, and the amino group is directed to
the other face of the ring. This arrangement allows the metal
fragment to sit within a pocket formed by the two phenyl rings.
There is no evidence for the formation of other isomers with trans
phenyl groups, or with cis phenyl groups on the i-Pr2N side of the
ring.
Reaction of 2 with benzylideneacetone (4-Phenyl-3-buten-2-
one) leads to (1 þ 4) addition to form the oxo-3-phospholene
complex 8 as the sole product (Scheme 4). The 31P NMR spectrum
of 8 shows a singlet
phenyl peaks, the 1H spectrum shows a doublet at
(JHP ¼ 27 Hz) for the CH to P, a broad multiplet at 5.49 for the
alkenyl hydrogen, and a singlet at 2.15 for the ring methyl group.
Compound 8 has been structurally characterized and an ORTEP
diagram is shown in Fig. 4. The cation consists of CpFe(CO)2 frag-
ment coordinated by an oxo-3-phospholene ring. The oxo-3-
phospholene ring is a planar. The amino group and the phenyl
group are directed to one face of the ring, and the CpFe(CO)2
fragment is directed to the other face of the ring.
d
198.8. In addition to the expected Cp, i-Pr, and
d
4.32
a
d
d
Reaction of 2 with azobenzene leads to a benzodiazophosphole
in a reaction that involves ortho CeH activation and proton transfer
to N (Scheme 5). This reactivity is the same as that reported for
stable cationic rhenium and cobalt phosphinidenes [16], but con-
trasts with that of neutral transient tungsten phosphinidenes,
which simply insert into an ortho CeH bond [25]. Compound 10
was characterized spectroscopically, and the spectral data are
consistent with the published data for rhenium and cobalt benzo-
diazoephosphole complexes. Notably, the NeH peak appears at
Fe1
P1
C9
C8
C10
d
7.39. Compound 10 has been structurally characterized, and an
C11
ORTEP diagram of the cation is shown in Fig. 5. The structure
consists of a CpFe(CO)2 unit coordinated by the benzodiazo-
phosphole ring. The ligand is oriented such that the amino group is
directed away from the Cp ring.
N1
2.2. PeN bond cleavage
Fig. 3. ORTEP diagram showing the structure of [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)-CH]
CHCH(Ph))}][AlCl4] (7). Thermal ellipsoids are shown at the 50% level. Hydrogen atoms
and the AlCl4 counterion have been omitted. Selected distances (A) and angles (deg):
ꢀ
Part of the reason for choosing an aminophosphinidene as our
ꢀ
starting point is the potential cleavability of the PeN bond. In
FeeP
¼
2.2570(9), PeN
¼
1.681(3), PeC8
¼
1.885(3), PeC9
¼
1.896(3), C8e
C10 ¼ 1.497(4), C9eC11 ¼ 1.488(5), C10eC11 ¼ 1.321(5), C8ePeC9 ¼ 93.9(1), PeC9e
C11
P ¼ 104.6(2).
¼
103.8(2), C9eC11eC10
¼
119.7(3), C11eC10eC8
¼
118.0(3), C10eC8e
Scheme 4.
Scheme 5.

350
K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
N3
N2
Fe1
Scheme 6.
P1
complete removal of amino group and the mass spectrum confirm
the presence of chlorine atom (m/z ¼ 425, 427).
Attempts to cleave the PeN bond of phosphirane complex 4 by
acid addition resulted in loss of styrene and formation of secondary
chloroaminophosphine complex 13 (Scheme 8). The 31P NMR
N1
spectrum (1H coupled) of 13 shows a doublet at
d 104.1 with a
1J(HP)¼ 473 Hz, indicating a direct PeH bond. The 1H NMR spec-
trum shows a peak at
d 8.81 with a large coupling constant that
matches that in 31P NMR spectrum. Compound 13 can be inde-
pendently synthesized by protonation of 1. The 2-phospholene
complexes 6 and 7, and oxo-phospholene complex 8 showed no
evidence of PeN cleavage under prolonged exposure to HCl(g) or
HBF4$Et2O.
Fig. 5. ORTEP diagram showing the structure of 10. Thermal ellipsoids are shown at
ꢀ
the 50% level. Hydrogen atoms and the AlCl4 counterion have been omitted. Selected
ꢀ
distances (A) and angles (deg): FeeP ¼ 2.2347(9), PeN1 ¼ 1.652(2), PeN2 ¼ 1.716(2),
PeC14 ¼ 1.796(3), N2eN3 ¼ 1.428(3), N3eC15 ¼ 1.412(4), C14eC15 ¼ 1.375(4), N1ePe
C14 ¼ 112.2(1), N2ePeC14 ¼ 89.9(1), N3eN2eP ¼ 113.6(2), C15eN3eN2 ¼ 109.4(2),
C15eC14eP ¼ 110.6(2), C14eC15eN3 ¼ 115.1(3).
2.3. Decomplexation
After the formation of phosphorus heterocyclic complexes using
the phosphinidene complex, the metal fragment can be removed
to isolate the metal free phosphorus heterocycles. We have found
that the simplest method is displacement of the P-heterocycle
with PMe3 or PEt3, leading to the cationic metal complexes
[CpFe(CO)2PR3]þ (14), which are readily separated from the neutral
P-heterocycle.
particular, conversion to a PeCl will lead to a useful substrate for
further elaboration. It is also potentially useful to cleave the PeN
bond while the P-heterocycle is coordinated to the metal fragment,
which serves as an effective protecting group for the phosphorus
lone pair.
Reaction of diphenylphosphirene complex 3 with PMe3 yields
complex 14 and the free aminophosphorus heterocycle 15
Reaction of the aminodiphenylphosphirene complex 3 with HCl(g)
yields the chlorodiphenylphosphirene complex 11 (Scheme 6). This
reaction is slow, requiring 8 h to complete amine cleavage. The PeN
cleavage reaction can also be carried using HBF4$Et2O. Here the
(Scheme 9). The 31P NMR spectrum of 15 shows a singlet at
d
ꢀ127.7
and 1H NMR spectrum shows the expected peaks for the phenyl
group and the isopropyl groups. The metal complex 14 shows a 31
P
ꢀ
AlCl4 counterion provides the Clꢀ nucleophile. Separation of the
chemical shift at
d ,
33.6 and CO stretches at 2052 and 2010 cmꢀ1
chlorodiphenylphosphirene complex 11 from the side product [H2N-
i-Pr2]þ X- (Xꢀ ¼ AlCl4ꢀ, BPh4ꢀ, BF4ꢀ) is difficult because both are
salts, and extraction of the desired product with a non-polar solvent
or selective precipitation is impossible. Column chromatography was
not possible on the cationic complexes. Compound 11 was eventually
purified by crystallization and manual separation. The difficult sep-
aration severely limits the utility of this reaction.
comparable to those of known [CpFe(CO)2(PR3)]þ complexes [26e
28]. The identity of 14 was also confirmed by X-ray crystallog-
raphy (see Supporting information).
Similar reactions of phospholene complexes 7 and 8 with PMe3
or PEt3 give free phospholenes 16 and 17 (Scheme 10). Displace-
ment of the phospholenes is slower, but can be accelerated with
heat. The 31P NMR spectrum of 16 shows a singlet at
d
91.4, while
The 31P NMR spectrum of 11 shows a characteristic high field
the 1H NMR spectrum shows doublets at
d 5.89 and 5.70 for the
shift at
1H NMR spectrum shows only multiplets at
rings and a singlet at 4.89 for the cyclopentadienyl ligand. Peaks
d
ꢀ52.0, confirming the retention of phosphirene ring. The
phospholene ring protons, as well as the expected phenyl and
d
7.93e7.73 for phenyl
isopropyl resonances. The 31P NMR spectrum of 17 shows a singlet
d
at
a doublet of doublets of quartets at
d
137.0. In the 1H NMR spectrum, the alkenyl hydrogen appears as
for isopropyl groups were not observed, confirming that the N-i-Pr2
group has been removed. The molecular ion in the electrospray
mass spectrum shows the expected mass and the characteristic
isotope pattern for a Cl atom (m/z ¼ 421, 423), confirming the
formula and the presence of chlorine. The infrared spectrum shows
carbonyl stretching frequencies at 2077 and 2038 cmꢀ1. When the
amine group is substituted by electronegative chlorine atom, the
carbonyl stretches shift to higher frequencies, indicating that the
chlorophosphirene is a weaker donor than the aminophosphirene.
For comparison, compound 3 shows carbonyl stretching fre-
d
5.07. A broad doublet at d 4.33
with phosphorus coupling of 32 Hz is assigned as the oxo-3-
quencies at 2059 and 2016 cmꢀ1
.
Reaction of the iron aminobenzodiazophosphole complex 10
with HBF4$Et2O yields chlorobenzodiazophosphole ꢀcomplex 12
(Scheme 7). This reaction is also slow, and the AlCl4 counterion
provides the Clꢀ nucleophile. Here again, the 1H NMR confirms the
Scheme 7.

K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
351
Scheme 8.
phospholene methyne proton. The isopropyl methyne and methyl
protons appear at 3.00 and 1.11 as broad peaks. Reaction of ami-
d
nobenzodiazophosphole complex 10 with trimethylphosphine
yields the expected iron phosphine complex 14, but the free ami-
nobenzodiazophosphole decomposes during workup.
Reaction of phosphirane complex 4 with phosphines does not
result in decomplexation. Instead styrene is displaced to form
phosphine coordinated phosphinidene complexes (Scheme 11).
Compound 18, the product that results from reaction of 4 with
triethylphosphine, has been fully characterized. The 31P NMR
Scheme 10.
4. Experimental section
4.1. General comments
spectrum shows doublets at
d 90.7 and 11.3 with a common
coupling constant 1J(PP) ¼ 517 Hz, confirming the direct PeP bond.
Compound 18 can also be formed by reaction of PEt3 with 2.
Decomplexation of the chlorophosphirene complex 11c occurs
All procedures were carried out under a nitrogen atmosphere
using standard Schlenk techniques or in an inert atmosphere glo-
vebox. Pentane was distilled from NaK2.8/benzophenone, THF was
distilled from Na/benzophenone, and dichloromethane and hexane
were purified using solvent purification columns containing
alumina (dichloromethane) or alumina and copper catalyst (hex-
ane). Deuterated chloroform was distilled from P2O5. The NMR
spectra were recorded in CDCl3, CD2Cl2 or DMSO-d6 using a Varian
Mercury 300 MHz spectrometer at 300.179 MHz (1H), 121.515 MHz
ꢀ
simply upon dissolution in THF. When compound 11c (BF4
counterion) was stirred in THF for 30 min the peak at
d
ꢀ52.0 in the
31P NMR spectrum disappeared and a new peak at
d
ꢀ80.7 was
observed. After pentane extraction the two products were sepa-
rated using chromatography on a silica gel column with dichloro-
methane eluent and were shown to be the chlorophosphirene 19
and [CpFe(CO)2F] (20) (Scheme 12). The spectra of 19 [29] and 20
[30] are consistent with the published data.
(
31P{1H}), 75.479 MHz (13C{1H}) or 282.449 (19F{1H}). Infrared
spectra were recorded in CDCl3 or CH2Cl2 solution using a Digilab
FTS-3000 spectrometer. Mass spectra of metal complexes were
obtained using a FinniganeMatt TSQ-700 mass spectrometer
equipped with electrospray ionization and a Harvard syringe pump.
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) was synthesized using
the published procedure [15]. Compound 2 was prepared using
modifications of the published procedure [15] as described below.
3. Conclusions
The cationic iron phosphinidene complex under examination
here undergoes cycloaddition reactions with a wide range of un-
saturated substrates, and primarily shows the typical reactivity
expected for electrophilic phosphinidene complexes. Attempts to
convert the amino group to a chloro group in the metal coordinated
heterocycles showed limited success. The conversion is only
possible for phosphirene and benzodiazophosphole complexes,
and even when the reaction is successful, separation and isolation
of the products tends to be difficult. Here, the cationic nature of the
metal complex is a distinct disadvantage. From this we conclude
that chlorination is best carried out after decomplexation. Chlori-
nation reactions of amino substituted P-heterocycles are well
described in the literature [31e35]. In decomplexation reactions,
the cation metal complex is advantageous because it allows sepa-
ration of neutral P-heterocycles from the metal complex via simple
extraction.
4.2. Cycloaddition reactions
4.2.1. [CpFe(CO)2{P(N-i-Pr2)(C(Ph)C(Ph)}][AlCl4] (3a)
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (100 mg,
0.291 mmol) was dissolved in CH2Cl2 (3 mL). Aluminium chloride
(38.8 mg, 0.291 mmol) was then added, resulting in the formation
of a red solution of 2a. Diphenylacetylene (51.9 mg, 0.291 mmol)
was added and the mixture was stirred for 15 min, resulting in a
reddish orange solution. The solvent volume was reduced to
w0.5 mL. Pentane (10 mL) was added slowly with vigorous stirring,
resulting in the formation of a yellow precipitate. The supernatant
was decanted and the solid was washed with pentane (3 ꢂ 1 mL),
Scheme 9.
Scheme 11.

352
K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
Addition of pentane (10 mL) resulting in the formation of a
brownish orange precipitate, which was washed with pentane and
dried. Yield: 58 mg, 73%. IR (CH2Cl2 solution, cmꢀ1):
CO ¼ 2073,
n
2035. 1H NMR:
d 5.33 (br s, 5H, C5H5), 3.98 (dt, 1H,
3J(HP) ¼ 3J(HH) ¼ 6.9 Hz, eCH ¼ ), 3.69 (sept, 2H, 3J(HH) ¼ 6.9 Hz,
NCH(CH3)2), 3.38 (m, 2H, P(CH2)CH
¼
), 2.81 (bd, 1H,
2J(HHgem) ¼ 18.0 Hz, PCHHC(CH3)), 2.81 (bd, 1H, 2J(HHgem) ¼ 18 Hz,
PCHHC(CH3)), 1.86 (s, 3H, CH3), 1.31(d, 12H, 3J(HH) ¼ 6.9 Hz,
Scheme 12.
CH(CH3)2). 31P{1H} NMR:
d d 209.5 (d,
126.5 (s), 13C NMR:
2J(CP) ¼ 24.6 Hz, Fe(CO)), 209.4 (d, 2J(CP) ¼ 24.8 Hz, Fe(CO)), 137.6
(d, 2J(CP) ¼ 8.7 Hz, ]C(CH)3), 121.3 (d, 2J(CP) ¼ 8.7 Hz, ]CH), 87.8
and dried under vacuum. Yield: 130 mg, 72%. IR (CH2Cl2 solution,
(s, C5H5), 51.3 (d, 2J(CP)
¼
3.4 Hz, CH(CH3)2), 46.2 (d,
cmꢀ1):
n
CO ¼ 2059, 2016. 1H NMR:
d
7.59e7.83 (m, Ph), 5.39 (d, 5H,
1J(CP) ¼ 33.4 Hz, P(CH2)C(CH3)]), 42.8 (d, 1J(CP) ¼ 32.6 Hz, P(CH2)
CH]), 23.8 (d, 3J(CP) ¼ 2.2 Hz, CH(CH3)2), 23.7 (d, 3J(CP) ¼ 2.2 Hz,
CH(CH3)2, 16.3 (d, 3J(CP) ¼ 8.7 Hz, ]C(CH3)). MS (electrospray,
CH2Cl2 solution): m/z ¼ 376 (Mþ). Compound 6 could not be crys-
tallized and satisfactory analysis could not be obtained. As a result,
the analogous compound 7 was prepared and fully characterized as
described below.
3J(HP) ¼ 1.5 Hz, C5H5), 3.57 (d sept, 2H, 3J(HH) ¼ 6.6 Hz,
3J(HP) ¼ 17.7 Hz, CH(CH3)2), 1.17 (d, 12H, 3J(HH) ¼ 6.6 Hz, CH(CH3)2).
31P{1H} NMR:
d
ꢀ69.7 (s), 31P NMR:
d
ꢀ69.7 (t, 3J(HP) ¼ 17.7 Hz).
13C NMR:
d
208.7 (d, 2J(CP) ¼ 31.9 Hz, Fe(CO)2), 150.7 (d,
1J(CP) ¼ 13.1 Hz, phosphirene ring C), 130.3 (s, p-Ph), 130.4 (s, m-
Ph), 129.4 (d, 3J(CP) ¼ 5.8 Hz, o-Ph), 127.1 (d, 2J(CP) ¼ 13.1 Hz, ipso-
Ph), 87.4 (s, C5H5), 49.4 (d, 2J(CP) ¼ 4.3 Hz, CH(CH3)2), 23.4 (d,
3J(CP) ¼ 3.4 Hz, CH(CH3)2). MS (electrospray, CH2Cl2 solution): m/
z ¼ 486 (Mþ). Anal. Calcd. For C27H29O2FePNAlCl4: C 49.50, H 4.46, N
2.14. Found: C 49.02, H 4.38, N 2.16.
4.2.5. [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)CH]CHCH(Ph))}][AlCl4] (7)
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (68.8 mg,
0.200 mmol) was dissolved in CH2Cl2 (3 mL). This solution was
added to AlCl3 (27.0 mg, 0.202 mmol). The resulting red solution of
[CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) was transferred to a Schlenk flask
equipped with a reflux condenser and then 1,4-diphenyl-1,3-
butadiene (41.2 mg, 0.200 mmol) was added. The resulting solu-
tion was heated under reflux for 8 h. The mixture was allowed to
cool to room temperature and the solvent volume was reduced to
w0.5 mL. Diethyl ether was added slowly with vigorous stirring,
resulting in the formation of a brownish orange precipitate. The
supernatant was decanted, and the solid was washed with diethyl
ether (3 ꢂ 1 mL) and dried under vacuum. Crude yield: 81 mg, 59%.
A portion of the precipitate (53.0 mg) was dissolved in CH2Cl2
(0.5 mL) and red-orange crystals were grown by slow diffusion of
diethyl ether into the CH2Cl2 solution at e 30 ꢁC. Overall yield:
4.2.2. [CpFe(CO)2{P(N-i-Pr2)(C(Ph)C(Ph)}][BPh4] (3b)
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (50.0 mg,
0.146 mmol) was dissolved in CH2Cl2 (3 mL). This solution was
added to sodium tetraphenylborate (49.8 mg, 0.146 mmol) and the
mixture was stirred for 15 min. The resulting red solution of
[CpFe(CO)2{PN-i-Pr2}][BPh4] (2b) was filtered through celite and
added to PhCCPh (26.0 mg, 0.146 mmol). The mixture was stirred
for 15 min, resulting in a reddish orange solution. The solvent
volume was reduced to w0.5 mL. The product was isolated as or-
ange crystals by slow diffusion of pentane into the CH2Cl2 solution
at ꢀ30 ꢁC. Yield: 68 mg, 58%.
4.2.3. [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)CH2)}][AlCl4] (4a, b)
31 mg, 35%. IR (CH2Cl2 solution, cmꢀ1):
n
CO ¼ 2053, 2011. 1H NMR:
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (50.0 mg,
0.146 mmol) was dissolved in CH2Cl2 (3 mL). This solution was
added to AlCl3 (29.0 mg, 0.217 mmol). To the resulting red solution
of [CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) was added styrene (60.8 mg,
d
7.17e7.40 (m, 10H, Ph), 6.23 (d, 2H, 2J(HP) ¼ 21.3 Hz, PCH(Ph)),
4.84 (d, 2H, 3J(PH) ¼ 11.1 Hz, ]CH), 4.30 (s, 5H, C5H5), 3.89 (sept, 2H,
3J(HH) ¼ 6.9 Hz, CH(CH3)2), 1.48 (d, 12H, 3J(HH) ¼ 6.9 Hz, CH(CH3)2).
31P{1H} NMR:
d
175.2 (s). 13C NMR:
d
209.0 (d, 2J(CP) ¼ 22.7 Hz,
0.584 mmol, 67
mL) and the mixture was stirred for 15 min,
Fe(CO)2), 137.7 (s, ]CH), 133.3 (d, 2J(CP) ¼ 9.7 Hz, ipso-Ph), 130.1 (s,
Ph), 129.8 (d, 4J(CP) ¼ 9.7 Hz, m-Ph), 129.2 (d, 3J(CP) ¼ 9.7 Hz, o-Ph),
87.3 (d, 2J(CP) ¼ 7.5 Hz, C5H5), 58.9 (br d, 1J(CP) ¼ 19.6 Hz, PC(Ph)),
52.5 (s, CH(CH3)2), 25.1 (s, CH(CH3)2). MS (electrospray, CH2Cl2 so-
lution): m/z ¼ 514 (Mþ). Anal. Calcd. For C29H33O2FePNAlCl4: C
50.98, H 4.87, N 2.05. Found: C 50.16, H 4.89, N 2.08.
resulting in a reddish orange solution. The solvent volume was
reduced to w0.5 mL. Addition of pentane (10 mL) resulted in a dark
orange oil, which was washed with pentane and dried. Yield:
59 mg, 70%. Red-orange X-ray quality crystals were grown by slow
diffusion of pentane into CH2Cl2 at ꢀ30 ꢁC, and shown to contain
4a, one of two diastereomers. IR (CH2Cl2 solution, cmꢀ1):
n
CO ¼ 2074, 2032. 31P{1H} NMR:
d
ꢀ52.0 (s) (81%), ꢀ53.8 (s) (19%).
4.2.6. Synthesis of [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)CHC(CH3)O)}]
[AlCl4] (8)
1H NMR (major diastereomer):
d 7.35e7.21 (m, Ph), 5.72 (s, C5H5),
3.59 (sept, 3J(HH) ¼ 6.9 Hz, NCH(CH3)2) 3.54 (sept, 3J(HH) ¼ 6.6 Hz,
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (150 mg,
0.437 mmol) was dissolved in CH2Cl2 (3 mL). This solution was
added to AlCl3 (58.3.0 mg, 0.437 mmol). To the resulting red solu-
tion of [CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) was added benzylide-
neacetone (63.8 mg, 0.437 mmol) and the mixture was stirred for
15 min, resulting in a reddish orange solution. The solvent volume
was reduced to w0.5 mL and diethyl ether (10 mL) was added
slowly with vigorous stirring, resulting in the formation of an or-
ange precipitate. Crude yield: 245 mg, 90%. A portion of the pre-
cipitate (40.0 mg) was dissolved in CH2Cl2 (0.5 mL) and crystals
were grown by slow diffusion of diethyl ether into the CH2Cl2 so-
lution at ꢀ30 ꢁC. Overall yield: 28 mg, 63%. IR (CH2Cl2 solution,
NCH(CH3)2), (s, 3J(HH) ¼ 2.72 (ddd, 3J(HH) ¼ 10.8 Hz, 3J(HH) ¼ 6.6
2
Hz, JHP
¼
10.8 Hz, CHPh), 2.01 (ddd, 3J(HH)
¼
10.8 Hz,
2J(HH) ¼ 2.4 Hz, 2J(HP) ¼ 10.8 Hz, CHH), 1.56 (d, 2J(HH) ¼ 6.6 Hz,
CHH), 1.38 (d, 3J(HH) ¼ 6.6 Hz, NCH(CH3)2), 1.37 (d, 3J(HH) ¼ 6.9 Hz,
NCH(CH3)2). Satisfactory analysis could not be obtained because 4
exists in solution as an equilibrium mixture, and bulk samples al-
ways contain a proportion of 2.
4.2.4. [CpFe(CO)2{P(N-i-Pr2)(CH2CHC(CH3)CH2)}][AlCl4] (6)
Compound 1 (50.0 mg, 0.146 mmol) was dissolved in CH2Cl2
(3 mL). This solution was added to AlCl3 (29.1 mg, 0.218 mmol). To
the resulting red solution of [CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) was
cmꢀ1):
n
CO ¼ 2058, 2016. 1H NMR:
d 7.46e7.23 (m, 5H, Ph), 5.49
added isoprene (19.7 mg, 0.292 mmol, 29
mL) and the mixture was
(broad d, 1H, 2J(HP) ¼ 27 Hz, ]CH), 5.47 (s, 5H, C5H5), 4.32 (broad
m, 1H, PCH), 3.53 (sept, 2H, 3J(HH) ¼ 6.6 Hz, CH(CH3)2), 2.15 (s, 3H,
stirred for 1 h. The solvent volume was reduced to w0.5 mL.

K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
353
CH3), 1.06 (d, 6H, 3J(HH) ¼ 6.6 Hz, CH(CH3)2), 0.99 (d, 6H,
contains [CpFe(CO)2{P(Cl)(C(Ph)C(Ph)}][BF4] (11c) and the side
product [H2N-i-Pr2][BF4]. Crude yield: 74 mg. A portion of the crude
precipitate (25 mg) was dissolved in CH2Cl2 (w1 mL) and filtered
three times through a celite plug. Yellow crystals of 11c were grown
by slow diffusion of pentane into the CH2Cl2 solution at ꢀ30 ꢁC.
Yield: 6 mg, 33%. Anal. Calcd. For C21H15O2FePClBF4: C 49.61, H 2.97.
Found: C 49.86, H 2.89. Spectroscopic data for 11c is identical to that
of 11a.
3J(HH) ¼ 6.6 Hz, CH(CH3)2). 31P{1H} NMR:
d
196.7 (s), 13C NMR:
d
208.2 (d, 2J(CP) ¼ 27.6 Hz, Fe(CO)2), 154.8 (s, POC), 134.2 (d,
2J(CP) ¼ 10.9 Hz, ipso-Ph),126.9 (s, o-Ph),128.7 (s, m-Ph),128.6 (s, p-
Ph), 104.8 (s, ]CH), 86.0 (s, C5H5), 63.7 (d, 1J(CP) ¼ 21.7 Hz, PC(Ph)),
52.4 (d, 2J(CP) ¼ 5.8 Hz, CH(CH3)2), 25.3 (s, CH(CH3)2, 22.9 (d,
3J(CP) ¼ 5.6 Hz, CH(CH3)2, 16.3 (d, 3J(CP) ¼ 5.1 Hz, CH3). MS (elec-
trospray, CH2Cl2 solution): m/z ¼ 454 (Mþ). Anal. Calcd. For
C
23H29O3FePNAlCl4: C 44.34, H 4.69, N 2.25. Found: C 44.13, H 4.71,
N 2.25.
4.3.3. Synthesis of [CpFe(CO)2{P(Cl)(PhNNHC6H4)}]
[(AlCl4)0.5(BF4)0.5] (12)
4.2.7. Synthesis of [CpFe(CO)2{P(N-i-Pr2)(PhNNHC6H4)}][AlCl4] (10)
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (175 mg,
0.509 mmol) was dissolved in CH2Cl2 (3 mL). This solution was
added to AlCl3 (69.0 mg, 0.510 mmol). The resulting red solution of
[CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) was added to azobenzene
(92.8 mg, 0.509 mmol) and the mixture was stirred for 1.5 h,
resulting in a deep red solution. The solvent was removed under
reduced pressure. The residue was washed with pentane (10 mL) to
give brown-yellow powder. Yield: 190 mg, 57%. IR (CH2Cl2 solution,
Compound 7 (40.0 mg, 0.061 mmol) was dissolved in CH2Cl2
(2 mL), HBF4$Et2O (29.8 mg, 25.0 mL, 0.184 mmol) was added, and
the resulting solution was stirred for 2 h. The solvent volume was
reduced to w0.2 mL and it was cooled ꢀ30 ꢁC, resulting in the
formation of orange crystals. Yield: 17 mg, 55%. IR (CH2Cl2 solution,
cmꢀ1):
n
CO ¼ 2074, 2037. 1H NMR (DMSO):
d 7.88e7.60 (m, 9H, Ph,
Ar), 7.59 (s,1H, NH), 5.34 (d, 5H, 3J(HP) ¼ 2.1 Hz, C5H5). 31P{1H} NMR
(DMSO):
d
144.4 (s). 13C NMR (DMSO):
d
210.9 (d, 2J(CP) ¼ 32.8 Hz,
Fe(CO)2), 152.8 (s, ipso-Ph), 151.6 (d, 2J(CP) ¼ 7.2 Hz, Ar),141.3 (s, Ar),
140.5 (s, Ar), 133.6 (s, Ar), 132.5 (s, p-Ph), 131.8 (d, 2J(CP) ¼ 9.4 Hz,
ipso-Ar),131.6 (d, 2J(CP) ¼ 9.4 Hz, Ar),130.1 (s, m-Ph),123.6 (s, o-Ph),
88.5 (s, C5H5). MS (electrospray, CH2Cl2 solution): m/z ¼ 425 (Mþ,
35Cl), 427 (Mþ, 37Cl). Anal. Calcd. For C19H15O2FePN2Cl3Al0.5B0.5F2: C
42.69, H 2.83. Found: C 42.64, H 3.11. Note: The presence of mixed
cmꢀ1):
n
CO ¼ 2047, 2005. 1H NMR: 7.86e7.06 (m, 9H, Ph, Ar), 7.39
(s, 1H, NH), 4.55 (d, 5H, 3J(HP) ¼ 1.5 Hz, C5H5), 3.55 (d sept, 2H,
3J(HH) ¼ 6.9 Hz, 3J(HP) ¼ 16.5 Hz, CH(CH3)2), 1.22 (d, 6H,
3J(HH) ¼ 6.6 Hz, CH(CH3)2), 1.03 (d, 6H, 3J(HH) ¼ 6.6 Hz, CH(CH3)2).
31P{1H} NMR:
d
117.5 (s). 13C NMR:
d
209.2 (d, 2J(CP) ¼ 28.4 Hz,
Fe(CO)2), 208.6 (d, 2J(CP)
¼
31.2 Hz, Fe(CO)2), 143.9 (d,
AlCl4ꢀ=BF4 counterions in the crystals was confirmed by 19F NMR
ꢀ
2J(CP) ¼ 8.0 Hz, ipso Ph), 142.5 (d, 2J(CP) ¼ 10.0 Hz, Ar), 132.4 (s, Ar),
130.0 (s, Ar), 128.9 (s, Ph), 128.0 (s, Ph), 126.5 (d, 1J(CP) ¼ 16.5 Hz,
ipso Ar), 123.5 (d, 2J(CP) ¼ 12.0 Hz, Ar), 123.3 (s, Ph), 121.8 (s, Ph),
117.7 (s, Ph), 114.1 (s, Ar), 87.2 (s, C5H5), 51.0 (d, 2J(CP) ¼ 6.6 Hz,
CH(CH3)2), 22.6 (s, CH(CH3)2), 22.4 (s, CH(CH3)2). MS (electrospray,
and negative ion electrospray MS.
4.3.4. Reaction of [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)CH2)}][AlCl4] (4)
with HCl
The compound [CpFe(CO)2{P(Cl)N-i-Pr2}] (1) (30.0 mg,
0.087 mmol) was dissolved in CH2Cl2 (3 mL). This solution was
added to AlCl3 (17.4 mg, 0.131 mmol). To the resulting red solution
of [CpFe(CO)2{PN-i-Pr2}][AlCl4] (2a) was added styrene (36.2 mg,
CH2Cl2 solution): m/z ¼ 490 (Mþ). Anal. Calcd. For C25H29O2N3
-
PFeAlCl4: C 45.56, H 4.43, N 6.38. Found: C 44.51, H 4.92, N 6.31.
4.3. PeN cleavage reactions
0.348 mmol, 40.0 mL)) and the mixture was stirred for 15 min,
resulting in a reddish orange solution of 4. Hydrogen chloride gas
was bubbled through CH2Cl2 (3 mL) and the resulting solution was
transferred via cannula into the solution of 4. After 30 min the
volume of the solvent was reduced to w0.5 mL under reduced
pressure and transferred into a NMR tube. Yellow crystals of
[CpFe(CO)2{PH(N-i-Pr2)(Cl)}][AlCl4] (13) were obtained by slow
diffusion of pentane into CH2Cl2 solution. Yield: 26 mg, 58%. IR
4.3.1. Reaction of [CpFe(CO)2{P(N-i-Pr2)(C(Ph)C(Ph)}][AlCl4] (3a)
with HCl
Compound 3a was prepared via reaction of 1 (82.0 mg,
0.239 mmol) with AlCl3 (32.0 mg, 0.240 mmol) in CH2Cl2, followed
by addition of diphenylacetylene (42.5 mg, 0.239 mmol). The
mixture was stirred for 15 min, resulting in a reddish orange so-
lution of 3a. HCl(g) was then bubbled through the solution for 3 min.
The flask was sealed and the solution was stirred for 15 h. The
solvent volume was reduced to w0.5 mL and diethyl ether (10 mL)
was added slowly with vigorous stirring, resulting in the formation
of a yellow precipitate, which contains [CpFe(CO)2{P(Cl)(C(Ph)
C(Ph)}][AlCl4] (11a) and the side product [H2N-i-Pr2]Cl. Crude yield:
96 mg. A portion of the crude precipitate (40 mg) was dissolved in
w1 mL of CH2Cl2 and filtered three times through a celite plug.
Single crystals were grown by slow diffusion of hexane into the
CH2Cl2 solution at e 30 ꢁC. Yield: 61 mg, 45%. IR (CH2Cl2 solution,
(CH2Cl2 solution, cmꢀ1):
n
CO ¼ 2073, 2035. 1H NMR:
d 8.79 (d, 1H,
1J(PH) ¼ 471 Hz, PH), 5.49 (d, 5H, 3J(HP) ¼ 2.1 Hz, C5H5), 3.81 (dsept,
2H, 3J(PH) ¼ 14.8 Hz, 3J(HH) ¼ 6.6 Hz, CH(CH3)), 1.46 (d, 6H,
3J(HH) ¼ 6.6 Hz, CH(CH3)), 1.35 (d, 6H, 3J(HH) ¼ 6.6 Hz, CH(CH3)).
31P{1H} NMR:
d
106.4 (s), 31P NMR:
d
106.4 (dt, 1J(PH) ¼ 471 Hz,
3J(PH) ¼ 14.8 Hz). MS (electrospray, CH2Cl2 solution): m/z ¼ 344
(Mþ, 35Cl), 346 (Mþ, 37Cl). Anal. Calcd. For C13H20O2FePNAlCl5: C
30.42, H 3.93, N 2.73. Found: C 30.45, H 3.85, N 2.62.
4.4. Decomplexation reactions
cmꢀ1):
n
CO ¼ 2077, 2038. 1H NMR:
d 7.93e7.73 (m, Ph), 4.89 (d, 5H,
3J(HP) ¼ 2.1 Hz, C5H5). 31P{1H} NMR:
d
ꢀ52.0 (s), 13C NMR:
d
206.3
4.4.1. Decomplexation of [CpFe(CO)2{P(N-i-Pr2)(C(Ph)C(Ph)}][AlCl4]
(3a)
Compound 3a (225 mg, 0.328 mmol) was dissolved in CH2Cl2.
Trimethylphosphine (49.9 mg, 0.656 mmol, 67.3 mL) was added and
the solution was stirred for 2 h. The solvent was removed under
reduced pressure, and the residue was extracted into pentane
(5 ꢂ 3 mL). The solvent volume was reduced to w1 mL under
reduced pressure and the pentane extract was cooled to ꢀ30 ꢁC for
48 h, resulting in the formation of pale yellow crystals of PN-i-
Pr2(C(Ph)C(Ph)) (15). The pentane insoluble residue was extracted
into CH2Cl2 (1 mL). Pentane (10 mL) was added slowly with mixing,
resulting in the formation of a yellow orange precipitate of
(d, 2J(CP) ¼ 30.5 Hz, Fe(CO)2), 144.5 (d, 1J(CP) ¼ 16.9 Hz, phos-
phirene ring C), 133.7 (s, p-Ph), 131.2 (d, 2J(CP) ¼ 7.2 Hz, ipso-Ph),
130.7 (s, m-Ph), 124.7 (s, o-Ph), 90.0 (s, C5H5). MS (electrospray,
CH2Cl2 solution): m/z ¼ 421(Mþ, 35Cl), 423 (Mþ, 37Cl).
4.3.2. Reaction of [CpFe(CO)2{P(N-i-Pr2)(C(Ph)C(Ph)}][AlCl4] (3a)
with HBF4$Et2O
Compound 3a (100 mg, 0.153 mmol) was dissolved in CH2Cl2
(2 mL) and HBF4$Et2O (73.8 mg, 0.459 mmol, 62.0 mL) was added.
The resulting solution was stirred for 10 h. Diethyl ether (8 mL) was
added, resulting in the formation of yellow precipitate, which

354
K. Vaheesar et al. / Journal of Organometallic Chemistry 745-746 (2013) 347e355
[CpFe(CO)2{P(PMe3)}][AlCl4] (14). The supernatant was decanted
and solid was dried under reduced pressure. The counterion AlCl4
was exchanged with BPh4 to grow single crystals. The solid 14
(43.0 mg, 0.100 mmol) and NaBPh4 (34.2 mg, 0.100 mmol) were
dissolved in CH2Cl2 (2 mL) and the resulting solution was stirred for
30 min. The precipitate formed was removed by filtration to form a
clear solution of [CpFe(CO)2{P(CH3)3}][BPh4]. Single crystals were
grown by slow diffusion of hexane into the CH2Cl2 solution
at ꢀ30 ꢁC. Compound 14: Yield: 102 mg, 64%. IR (CH2Cl2 solution,
i-Pr2)(PEt3)}][AlCl4] (18) were obtained by slow diffusion of hexane
into CH2Cl2 solution. Yield: 35 mg, 51%. IR (CH2Cl2 solution, cmꢀ1):
n
CO ¼ 2048, 2000. 1H NMR:
d
5.16 (d, 5H, 3J(HP) ¼ 2.7 Hz, C5H5),
3.27 (br, 2H, CH(CH3)), 2.12 (dq, 6H, 2J(PH)
¼
10.0 Hz,
3J(HH) ¼ 7.6 Hz, PCH2CH3), 1.33 (d t, 9H, 3J(PH) ¼ 15.8 Hz,
3J(HH) ¼ 7.6 Hz, PCH2CH3), 1.17 (d, 12H, 3J(HH) ¼ 6.6 Hz, CH(CH3)).
31P NMR:
d
84.6 (br d, 1J(PP)
¼
514 Hz, FePP), 33.4 (br
d
1J(PP) ¼ 514 Hz, FePP). Anal. calcd. for C19H34O2FeP2NAlCl4: C
38.35, H 5.76, N 2.35. Found: C 38.41, H 5.45, N 2.26.
cmꢀ1):
n
CO ¼ 2052, 2010. 1H NMR:
d
5.42 (d, 5H, 3J(HP) ¼ 1.5 Hz,
C5H5), 1.82 (d, 9H, 2J(PH) ¼ 11.1 Hz, PCH3). 31P{1H} NMR:
d
33.5 (s),
4.4.5. Decomplexation of [CpFe(CO)2{P(Cl)(C(Ph)C(Ph)}][BF4] (11c)
Compound 11c (191 mg, 0.376 mmol) was dissolved in THF and
stirred for 30 min. The THF was removed under reduced pressure
and the residue was dissolved in CH2Cl2. Column chromatography
(silica gel, CH2Cl2 eluent) was used to isolate two fractions, one
colourless and one orange. The solvent was removed under reduced
pressure and the products were dissolved in pentane (1 mL). The
pentane extracts were cooled to ꢀ30 ꢁC for 60 h, resulting in the
formation of white crystals of PCl(C(Ph)C(Ph)) (19) and orange
crystals of [CpFe(CO)2PF] (20). Compound 19: Yield: 28 mg, 46%. 1H
31P NMR:
d
33.5 (dec., 2J(PH) ¼ 11.1 Hz). MS (electrospray, CH2Cl2
solution): m/z ¼ 253 (Mþ). Compound 15: Yield: 38 mg, 37%. 1H
NMR:
d
7.33e7.81 (m, 10H, Ph), 3.16 (d sept, 3J(PH) ¼ 8.7 Hz, 3J
(HH) ¼ 6.6 Hz, CH(CH3)2), 1.10 (d, 3J(HH) ¼ 6.6 Hz, CH(CH3)2). 31P
{1H} NMR:
d
ꢀ125.1 (s). 13C NMR:
d
136.0 (d, 1J(CP) ¼ 53.7 Hz,
phosphirene ring C), 131.9 (d, 2J(CP) ¼ 5.8 Hz, ipso-Ph), 130.4 (s, o-
Ph), 129.6 (s, m-Ph), 128.6 (s, p-Ph), 43.9 (d, 2J(CP) ¼ 6.6 Hz,
CH(CH3)2), 23.8 (d, 3J(CP) ¼ 8.0 Hz, CH(CH3)2). Anal. Calcd. For
C
20H24PN: C 77.64, H 7.82, N 4.53. Found: C 77.64, H 7.81, N 4.57.
NMR:
d
d
7.52e7.99 (m, Ph). 31P{1H} NMR:
d
ꢀ80.7 (s). 13C NMR:
4.4.2. Decomplexation of [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)
CHCHCH(Ph))}][AlCl4] (7)
134.7 (d, 1J(CP) ¼ 65.5, phosphirene C), 129.9 (s, C-Ph), 128.2 (s, C-
Ph), 126.4 (d, 2J(CP) ¼ 8.8 Hz, ipso-Ph). Compound 20: Yield: 47 mg,
Compound 7 was (112 mg, 0.164 mmol) dissolved in CH2Cl2.
87%. IR (CH2Cl2 solution, cmꢀ1):
n
CO ¼ 2057, 2012. 1H NMR:
d 4.98
Triethylphosphine (38.8 mg, 0.328 mmol, 48
mL) was added and the
(s, C5H5). 19F{1H} NMR:
d
ꢀ149.2 (s).
resulting solution was refluxed for 10 h. The solvent was removed
under reduced pressure and the product was extracted in pentane
(10 mL). Pentane was removed under reduced pressure and pale
yellow solid P(N-i-Pr2)(CH(Ph)CHCHCH(Ph)) (16) was obtained.
4.5. X-ray crystallography
Suitable crystals of compounds 3b, 4a, 7, 8, 10, and 14 were
mounted on glass fibres. Programs for diffractometer operation,
data collection, cell indexing, data reduction and absorption
correction were those supplied by Bruker AXS Inc., Madison, WI.
Diffraction measurements were made on a PLATFORM diffractom-
Yield: 31 mg, 56%. 1H NMR:
d 7.17e7.40 (m, Ph), 5.89 (d,
2J(HP) ¼ 8.1 Hz, PCH(Ph)), 4.11 (d, 3J(PH) ¼ 5.7 Hz, eCH ¼ ), 3.45 (b,
CH(CH3)2), 0.98 (d, 3J(HH) ¼ 6.6 Hz, CH(CH3)2). 31P{1H} NMR:
d 91.4
(s). 13C NMR:
d
144.0 (d, 2J(CP) ¼ 15.4 Hz, ]CH), 133.6 (d,
2J(CP) ¼ 11.0 Hz, ipso-Ph), 128.5 (d, 5J(CP) ¼ 2.2 Hz Ph), 127.7 (d,
eter/SMART 1000 CCD using graphite-monochromated Mo-Ka ra-
4J(CP) ¼ 6.6 Hz, m-Ph), 125.8 (d, 3J(CP) ¼ 2.9 Hz, o-Ph), 51.2 (d,
diation at ꢀ80 ꢁC. The unit cell was determined from randomly
selected reflections obtained using the SMART CCD automatic
search, centre, index and least-squares routines. Integration was
carried out using the program SAINT and an absorption correction
was performed using SADABS. Structure solution was carried out
using the SHELX97 [36] suite of programs and the WinGX graphical
interface [37]. Initial solutions were obtained by direct methods
and refined by successive least-squares cycles. All non-hydrogen
atoms were refined anisotropically.
2J(CP)
¼
19.2 Hz, CH(CH3)2), 46.9 (br, PC(Ph)), 24.2 (d,
3J(CP) ¼ 5.9 Hz, CH(CH3)2).
4.4.3. Decomplexation of [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)CHC(CH3)
O)}][AlCl4] (8)
Compound 8 (245 mg, 0.393 mmol) was dissolved in CH2Cl2
(5 mL) and transferred to a Schlenk flask. Trimethylphosphine
(44.8 mg, 0.590 mmol, 61.0 mL) was added and the resulting solu-
tion was stirred for 1 h. The solvent was removed under reduced
pressure and the product was extracted in pentane (10 mL).
Pentane was removed under reduced pressure and P(N-i-
Pr2)(CH(Ph)CHC(CH3)O) (17) was obtained as a colourless oil. Yield:
Acknowledgements
This work was financially supported by the University of Regina.
We also thank Bob McDonald and Mike Ferguson (University of
Alberta) for X-ray data collection.
53 mg, 47%. 1H NMR:
d 7.05e7.22 (m, Ph), 5.04 (ddq, 1H,
3J(PH) ¼ 10.2 Hz, 3J(HH) ¼ 0.9 Hz, 4J(HH) ¼ 1.8 Hz, ]CH), 4.33 (br d,
1H, 2J(PH) ¼ 32.1 Hz, PC(Ph)H), 3.00 (b, 2H, CH(CH3)2), 1.90 (d, 3H,
4J(HH) ¼ 1.6 Hz, CH3), 1.11 (b, 12H, CH3). 31P{1H} NMR:
d C
137 (s). 13
11.5 Hz, ]C(Me)O), 130.9 (d,
Appendix A. Supplementary material
NMR:
d
156.6 (d, 2J(CP)
¼
2J(CP) ¼ 8.8 Hz, ipso-Ph), 128.2 (s, Ph), 125.5 (s, Ph), 97.8 (s, ]CH),
50.2 (d, 1J(CP) ¼ 28.2 Hz, PCH(Ph)), 29.9 (s, CH(CH3)2), 24.7 (s, CH3),
16.6 (s, CH(CH3)2).
CCDC 945774, 945775, 945776, 945777, 945778 and 945779
contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
4.4.4. Reaction of [CpFe(CO)2{P(N-i-Pr2)(CH(Ph)CH2)}][AlCl4] with
PEt3 (4)
Compound 4 was prepared from 1 (40.0 mg, 0.116 mmol), AlCl3
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