Template synthesis of 1,4,7-triphosphacyclononanes

Article abstract of DOI:10.1021/ja0578956

Iron(II) templates based on a [(η⁵-Cp^R)Fe] ⁺ core have been employed for the successful synthesis of 1,4,7-triphosphacyclononane derivatives (9-aneP₃R′₃) from a range of appropriately functionalized coordinated diphosphines and monophosphines. 1,2-Diphosphinoethane (1,2-dpe) or (2-phosphinoethyl)- phenylphosphine (Phdpe) undergo a base-catalyzed Michael-type addition to trivinylphosphine, divinyl-(benzyl)phosphine, ordivinyl(phenyl)phosphine in [(η⁵-Cp^R)Fe(diphosphine)(monophosphine)]⁺ complexes (2a-j) to give [(η⁵-Cp^R)Fe(9aneP ³R′³)]+ derivatives (4a-j) containing coordinated triphosphacyclononanes bearing one (with Phdpe) or two (with 1,2-dpe) secondary phosphine donors. The rates of macrocyclization show a dependence on the nature of the substituent(s) R on the cyclopentadienyl ligand with increased rates being observed along the series R = H₅ < (Me₃Si)H ₄ < 1,3-(Me₃Si)₂H₃ ≈ Me ₅. For coupling reactions with trivinylphosphine, a pendant vinyl function remains in the macrocyclic product (4a-g) which is readily hydrogenated to the corresponding ethyl derivatives (5a-g). Further functionalization of coordinated secondary phosphines in the initially formed macrocycles (5a-g) is achieved by proton abstraction followed by addition of the appropriate alkyl halide electrophile and gives rise to tritertiary-triphospha-cyclononanes (7a-g, 71, 7m). All new complexes have been fully characterized by spectroscopic and analytical methods in addition to the structural determination by single-crystal X-ray techniques of [η⁵-(Me₃Si)₂C ₅H₃)Fe(9-aneP₃H₂C₂H ₃)]PF₆, 4c, and [η⁵-Me₃SiC ₅H₄)Fe(9-aneP₃Et₃)]BF₄, 7b. 1,4,7-Triethyl-1,4,7-triphosphacyclononane is released from its metal template (7a, 7b) by treatment with either H₂O₂ or Br ₂/H₂O to give the trioxide 9-aneP₃(O) ₃Et₃ (8). Attempts to recover the trivalent phosphorus species, 1,4,7-triethyl-1,4,7-triphosphacyclononane, from the trioxide by reduction proved unsuccessful.

Full text of DOI:10.1021/ja0578956

Published on Web 02/18/2006
Template Synthesis of 1,4,7-Triphosphacyclononanes
Peter G. Edwards,* Robert Haigh, Dongmei Li, and Paul D. Newman
Contribution from the School of Chemistry, Cardiff UniVersity, Main Building,
Cardiff CF10 3AT, United Kingdom
Received December 6, 2005; E-mail: edwardspg@cardiff.ac.uk
Abstract: Iron(II) templates based on a [(η5-CpR)Fe]+ core have been employed for the successful synthesis
of 1,4,7-triphosphacyclononane derivatives (9-aneP3R′3) from a range of appropriately functionalized
coordinated diphosphines and monophosphines. 1,2-Diphosphinoethane (1,2-dpe) or (2-phosphinoethyl)-
phenylphosphine (Phdpe) undergo a base-catalyzed Michael-type addition to trivinylphosphine, divinyl-
(benzyl)phosphine, or divinyl(phenyl)phosphine in [(η5-CpR)Fe(diphosphine)(monophosphine)]+ complexes
(2a-j) to give [(η5-CpR)Fe(9aneP3R′3)]+ derivatives (4a-j) containing coordinated triphosphacyclononanes
bearing one (with Phdpe) or two (with 1,2-dpe) secondary phosphine donors. The rates of macrocyclization
show a dependence on the nature of the substituent(s) R on the cyclopentadienyl ligand with increased
rates being observed along the series R ) H5 < (Me3Si)H4 < 1,3-(Me3Si)2H3 ≈ Me5. For coupling reactions
with trivinylphosphine, a pendant vinyl function remains in the macrocyclic product (4a-g) which is readily
hydrogenated to the corresponding ethyl derivatives (5a-g). Further functionalization of coordinated
secondary phosphines in the initially formed macrocycles (5a-g) is achieved by proton abstraction followed
by addition of the appropriate alkyl halide electrophile and gives rise to tritertiary-triphospha-cyclononanes
(7a-g, 7l, 7m). All new complexes have been fully characterized by spectroscopic and analytical methods
in addition to the structural determination by single-crystal X-ray techniques of [{η5-(Me3Si)2C5H3)Fe(9-
aneP3H2C2H3)]PF6, 4c, and [(η5-Me3SiC5H4)Fe(9-aneP3Et3)]BF4, 7b. 1,4,7-Triethyl-1,4,7-triphosphacy-
clononane is released from its metal template (7a, 7b) by treatment with either H2O2 or Br2/H2O to give the
trioxide 9-aneP3(O)3Et3 (8). Attempts to recover the trivalent phosphorus species, 1,4,7-triethyl-1,4,7-
triphosphacyclononane, from the trioxide by reduction proved unsuccessful.
Introduction
complexes of these macrocycles, and control of the stereochem-
istry is of value. There are examples where the absence of
The study of the coordination chemistry of small ring
macrocycles has been, and continues to be, dominated by
homoleptic oxa-, aza-, and thia-carbocyclic systems and some,
mostly oxa/aza, mixed donor species. Related phosphorus
analogues have, by comparison, been poorly investigated, a
surprising anomaly given the importance of acyclic phosphines
as ligands in catalysis and in the stabilization of unusual classes
of complexes. The scarcity of studies of phosphorus macrocycles
is probably due largely to a lack of appropriate precursors for
cyclization (e.g., P-tosyl analogues of the N-tosyl derivatives
used extensively in the preparation of N3 and N4 systems are
unstable) and synthetic difficulties arising from the inherent air-
sensitivity of most tervalent phosphorus species. There have
been significant advancements in the synthesis and coordination
chemistry of homoleptic P3 and P4 macrocycles. Most of the
early preparations of Horner1 and Kyba2 were by direct solution
methods (nontemplate assisted), which were consequently
nonstereoselective, giving all possible isomers of the respective
macrocycles. The relative stereochemistry at the phosphorus
centers has implications for the coordination behavior in metal
stereoselectivity may be overcome by the inversion of phos-
phorus centers upon coordination, such as in Kyba’s 11-aneP3
macrocycle, where the cis, cis, cis/cis, cis, trans (or syn, syn/
syn, anti) mixture could be used directly for the preparation of
a number of complexes although elevated temperatures (boiling
xylenes) were required to invert the phosphorus and force the
facially capping coordination mode of the syn, anti isomer and
formation of the complex.2 Metal template approaches pioneered
by Horner3 and exploited by a number of groups, including
Stelzer,4 Norman,5 and more recently us,6 have for the most
part replaced the nontemplate syntheses. Stelzer largely initiated
the use of metal templates for the synthesis of tetradentate P4
systems, and his group has continued to examine the synthesis
and complexation chemistry of these interesting ligands.4
Norman was the first to employ a template for the preparation
of terdentate P3 macrocycles (12-aneP3R3 and 15-aneP3R3) via
intramolecular hydrophosphination reactions of coordinated
(3) Horner, L.; Kunz, H. Chem. Ber. 1971, 104, 717.
(4) (a) Brauer, D. J.; Do¨rrenbach, F.; Lebbe, T.; Stelzer, O. Chem. Ber. 1992,
125, 1785. (b) Brauer, D. J.; Lebbe, T.; Stelzer, O. Angew. Chem. 1988,
100, 432.
(5) Diel, B. N.; Brandt, P. F.; Haltiwanger, R. C.; Norman, A. D. J. Am. Chem.
Soc. 1982, 104, 4700.
(1) Horner, L.; Walach, P.; Kunz, H. Phosphorus Sulf Relat. Elem. 1978, 5,
171.
(2) Kyba, E. P.; John, A. M.; Brown, S. B.; Hudson, C. W.; McPhaul, M. J.;
Harding, A.; Larsen, K.; Niedzwiecki, S.; Davis, R. E. J. Am. Chem. Soc.
1980, 102, 139.
(6) (a) Edwards, P. G.; Fleming, J. S.; Liyanage, S. S. Inorg. Chem. 1996, 35,
4563. (b) Edwards, P. G.; Fleming, J. S.; Liyanage, S. S. J. Chem. Soc.,
Dalton Trans. 1996, 1801.
9
3818
J. AM. CHEM. SOC. 2006, 128, 3818-3830
10.1021/ja0578956 CCC: $33.50 © 2006 American Chemical Society

Template Synthesis of 1,4.7-Triphosphacyclononanes
A R T I C L E S
primary alkenyl phosphines, although the ligand was not released
from the Mo(0) center upon which it was formed and its
coordination chemistry remained unexplored.5 Functionalization
and liberation of Norman’s 12-aneP3H3 macrocycle was achieved
by us and allowed the study of the coordination chemistry of
various 12-aneP3R3 derivatives.6 More recently, Gladysz and
co-workers have reported very large ring P3 macrocycles which
have also been formed upon a group 6 metal tricarbonyl template
although by a ring-closing metathesis reaction of coordinated
alkenyl phosphines.7 Our interest in triphosphorus macrocycles
of this nature stems from their ability to facially cap a
coordination polyhedron (thus forcing remaining reaction sites
into mutually cis orientations opposite the trans-labilizing
phosphine donors) while also forming robust metal-ligand
fragments. Our early studies of complexes of 12-aneP3R3 ligands
do indeed indicate that these principles can lead to unusual
structures and reactivity. In this context, we have shown that
“simple” (12-aneP3R3)MCl3 complexes (M ) Ti, V, Cr) are
active in alkene polymerization with selectivity being influenced
by the nature of R8 and that (12-aneP3Et3)Mn(I) carbonyl
complexes are active ROMP catalysts (for which Mn is not well-
known).9 A disadvantage of the relatively large 12-aneP3R3
ligands is that they appear to remain flexible enough to limit
stability of complexes of metals not so well suited to forming
tertiary phosphine complexes (e.g., f-elements), as might be
expected by comparison with related 9-membered and 12-
membered N3 macrocycles, where larger ring sizes lead to
increased ligand lability.10 Thus synthetic routes to smaller ring
sizes remain important goals, and our target is the class of
ligands based upon the elusive 9-membered triphosphacy-
clononane core structure.
clononane derivatives using an Fe(II) template system with
variously functionalized Cp ligands.
Results and Discussion
9-aneP3R3 Derivatives from Template Reactions of 1,2-
Diphosphinoethane and Trivinylphosphine. The starting point
for all the macrocycle syntheses described herein is from the
[(η5-CpR)Fe(CH3CN)(diphos)]X (CpR ) Me5Cp or Cp*, {Me3Si}-
C5H4, 1,3-{Me3Si}2C5H3; X ) BF4-, PF6-) precursor com-
plexes, 1a-g. These are readily obtained from the respective
[(η5-CpR)Fe(CH3CN)(CO)2]X complexes by the photolytically
activated substitution of the carbonyl donors in the presence of
1,2-diphosphinoethane (1,2-dpe) or phenyl(2-phosphinoethyl)-
phosphine (Phdpe) and in a manner similar to that described
by Astruc for related systems.14 The compounds are red solids
that are readily recrystallized from tetrahydrofuran, although
they are susceptible to dissociation of coordinated acetonitrile,
and reliable, reproducible analytical and mass spectroscopic data
were not obtained for the compounds. Coordination of the
diphosphine in 1a-g was confirmed by the 31P{1H} NMR
spectra of the complexes which showed the usual downfield
shifts compared to the uncoordinated ligands. The ν(P-H) and
ν(CtN) stretches were observed in the infrared spectra of the
complexes as detailed in the Experimental Section.
In all cases, the acetonitrile-diphosphine complexes decom-
pose in hydrochlorocarbon solvents in which they are initially
readily soluble.
The labile acetonitrile in the 1,2-diphosphinoethane com-
plexes [(η5-CpR)Fe(1,2-dpe)(MeCN)]+, 1a-d, may be substi-
tuted with trivinylphosphine (tvp), divinylalkylphosphines, or
divinylarylphosphines on heating in anisole, 1,2-dichloroethane,
or chlorobenzene (Scheme 1). The substitution is conveniently
followed by 31P{1H} NMR spectroscopy and is accompanied
by a color change from the red of the acetonitrile complexes to
a lighter orange-yellow of the trivinylphosphine complexes.
Isolation of pure 2a-d was compromised by the facile
subsequent intramolecular ring-closure (see below), and in all
cases, attempts at recrystallization resulted in contamination by
the linear triphosphine complexes of type 3. Typically, the
resultant quaternary intermediate complexes [(η5-CpR)Fe(1,2-
dpe)(tvp)]+, 2a-d, were not isolated and were characterized
only by their 31P{1H} NMR spectra, which consist of the
expected doublet (2 × RPH2) and triplet P(C2H3)3 (2JP-P ∼ 50
Hz) of an A2B pattern. For the template reactions using 1,2-
diphosphinoethane and trivinylphosphine, the first coupling
reaction to give the half-cycle (2 f 3) proceeds soon after
complexation of the tertiary phosphine for the silylated cyclo-
pentadienyl derivatives [(η5-Me3SiCp)Fe(1,2-dpe)(tvp)]+, 2b,
and [{η5-(Me3Si)2Cp}Fe(1,2-dpe)(tvp)]+, 2c, as evidenced by
the appearance of three distinct multiplets (AMX pattern) in
the 31P{1H} NMR spectra. The first coupling is somewhat
slower for the Cp* derivative (2d f 3d) and considerably slower
for the unsubstituted (parent) Cp derivative (2a f 3a). Further
heating leads to the disappearance of the signals attributed to 2
and a gradual growth of those of 3 as well as the final product
4. The second coupling to give the final macrocycle product (3
f 4) is slower than the first, but the presence of 4 may be
observed before complete conversion of 2 to 3. The reactions
are conveniently monitored by 31P{1H} NMR spectroscopy, as
In related work, Mathey and co-workers prepared 12-aneP3
macrocycles containing sp2-type (σ2,λ3) phosphorus centers by
the nontemplate coupling of azaphosphinines with alkynes.11
The silicon-based 1,4,7-triphospha-2,3,5,6,8,9-hexasilanonane
was the first 9-membered macrocycle with three σ3,λ3 phos-
phorus donors,12 although the free macrocycle was not isolated;
the hydrolytically unstable P-Si linkages are unlikely to survive
the conditions required for attempted liberation and will
substantially limit coordination chemistry and applications. In
view of the potential of triphosphacyclononanes in coordination
chemistry and applications, we have continued to investigate
alternative metal templates suitable for the closure of smaller
ring systems. We have recently reported preliminary results of
this study, including the application of cyclopentadienyliron(II)
templates, to the synthesis of 9-, 10-, and 12-membered P3
macrocycles.13 In this paper, we present full details of the
preparation and characterization of the first 1,4,7-triphosphacy-
(7) Bauer, E. B.; Ruwwe, J.; Mart´ın-Alvarez, J. M.; Peters, T. B.; Bohling, J.
C.; Hampel, F. A.; Szafert, S.; Lis, T.; Gladysz, J. A. J. Chem. Soc., Chem.
Commun. 2000, 2261.
(8) Baker, R. J.; Edwards, P. G. J. Chem. Soc., Dalton Trans. 2002, 2960.
(9) Baker, R. J.; Edwards, P. G.; Gracia-Mora, J.; Ingold, F.; Malik, K. M. A.
J. Chem. Soc., Dalton Trans. 2002, 3985.
(10) Critical Stability Constants; Smith, R. M., Martell, A. E., Eds.; Plenum:
New York, 1989; Vols. 5 and 6.
(11) Avarvari, N.; Maigrot, N.; Ricard, L.; Mathey, F.; Le Floch, P. Chem.s
Eur. J. 1999, 5, 2109.
(12) Driess, M.; Faulhaber, M.; Pritzkow, H. Angew. Chem., Int. Ed. Engl. 1997,
36, 1892.
(13) (a) Edwards, P. G.; Newman, P. D.; Hibbs, D. E. Angew. Chem., Int. Ed.
2000, 39, 2722. (b) Edwards, P. G.; Newman, P. D.; Malik, K. M. A.
Angew. Chem., Int. Ed. 2000, 39, 2922. (c) Price, A. J.; Edwards, P. G. J.
Chem. Soc., Chem. Commun. 2000, 899.
(14) Catheline, D.; Astruc, D. Organometallics 1984, 3, 1094.
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3819

A R T I C L E S
Scheme 1
Edwards et al.
illustrated in Figure 1. Proton-coupled 31P NMR spectroscopy
allows the unequivocal assignment of each signal in the AMX
spectra of 3a-d to the appropriate primary, secondary, and
tertiary phosphorus centers (Table 1).
While electronic differences between the different CpRFe+
templates may influence the rate of cyclization, these effects
are likely to be small, and the observation of faster rates of
macrocycle formation with the Cp units bearing bulky fragments
may be explained, in part, by steric influences upon the
coordinated 1,2-dpe and tvp precursor phosphines. It is reason-
able to presume that the presence of bulky groups at the
periphery of the Cp ligand will effectively compress the
P-Fe-P bond angles, resulting in a closer approach of the vinyl
functions of the tvp to the primary phosphines and lead to an
enhancement of rate of the hydrophosphination as a result of
this “proximity” effect. It is noteworthy that, although the
electronic differences between Cp and Me3SiCp are slight, the
relative rates of macrocycle formation for these two templates
are significantly different. The greatest yields (and indeed rates
of formation) of macrocycle were observed with the bulkier CpR
derivatives, Cp itself giving the lowest yield of macrocyclic
product. For related tris-primary phosphine and 12-aneP3R3
complexes of Fe(II), we have demonstrated that increasing the
bulk of the trans (to P) ligands does indeed reduce the
nonbonded P-P distances.16 This steric compression is also
evident in the crystal structures of the macrocyclic products as
discussed below.
As well as being sensitive to the nature of the substituents
on the Cp ring, the rate of each coupling reaction (2 f 3 and
3 f 4) is also accelerated in the presence of base. Without added
base, macrocycle formation was complete after 24 to 48 h at
80 °C with the Cp*, Me3SiCp, and (Me3Si)2Cp templates for
the archetypal trivinylphosphine system. If the trivinylphosphine
was added in excess, a significant rate enhancement was
observed. Rate enhancement was also observed when stoichio-
metric amounts of triethylamine were added and reaction times
were consequently reduced to several hours. In contrast, for the
Cp derivative in the absence of added base, only the intermediate
complex 3a and starting material 2a were observed in the
31P{1H} NMR spectrum after 5 days heating at 80 °C, and the
final ring closure to form the macrocycle was only achieved
after the addition of Et3N; even then, several days at 80 °C
were required for completion (Figure 1). This behavior implies
that formation of the linear P3 intermediates, and subsequently
the product 9-aneP3 macrocycles, requires the generation of an
accessible lone pair on a coordinated primary (or secondary)
phosphine by proton abstraction. An observable color change
(upon addition of base) from yellow to red is consistent with
formation of a coordinated phosphide, in accord with the
(15) No attempt was made to isolate the linear P3 complexes of type 3 as they
were only ever observed as mixtures with the respective starting materials
(2) and macrocyclic products (4).
(16) Edwards, P. G.; Malik, K. M. A.; Ooi, L.; Price, A. J. J. Chem. Soc., Dalton
Trans. 2006, 433.
Figure 1. 31P{1H} NMR spectra showing the conversion of 2a into 4a at
80 °C in the presence of added Et3N. The bottom trace was recorded after
1 h, the middle trace after 18 h, and the upper trace after 72 h.
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Template Synthesis of 1,4.7-Triphosphacyclononanes
A R T I C L E S
Table 1. P{1H} NMR Data for the Complexes15
complex
δP (JPP
)
complex
δP (JPP)
1a
1b
1c
1d
1e
1f
0.5s
3.0s
1.5s
7.0s
4a
4b
4c
4d
4e
4f
129.0t (22), 96.0d (22)
131.0t (21), 98.4d (21)
126.0t (18), 98.7d (18)
117.0t (5), 108.2d (5)
134.2t (21), 129.3t (21), 96.0t (21)
129.7t (18), 125.7t (18, 100.1t (18)
134.6t (18), 133.9t (18), 129.9t (18),
128.6t (18), 100.1t (18), 99.2t (18)
129.8t (18), 97.0d (18)
74.8d (33), 63.8d (36), 3.7d (36), 2.7d (33)
72.5d (36), 61.4d (33), 3.8d (33), 1.6d (36)
75.4d (33), 74.7d (33), 63.8d (33), 3.9d (33),
3.1d (33), 2.3d (33)
1g
4g
4h
4i
4j
2a
2b
2c
2d
2h
2i
51.9t (58), 3.5d (58)
50.8t (59), 4.3d (59)
48.5t (49), 7.0d (49)
49.5t (47), 15.5d (47)
54.5t (58), 5.9d (58)
57.1t (47), 16.6d (47)
51.6t (47), 13.7d (47)
90.8dd (36,49), 85.8t (36), 7.2dd (36,49)
87.8m, 8.0dd (42,46)
119.7t (4), 106.0d (4)
118.9t (4), 106.3d (4)
5b
5c
5e
5f
6a
6b
140.2t (21), 97.5d (21)
136.5t (21), 97.1d (21)
139.4t (21), 134.1t (21), 96.4t (21)
136.2t (24), 129.4t (24), 99.6t (24)
140.3d (25), 131.1t (25)
2j
3a
3b
3c
3d
3h
138.9d (25), 128.5t (25)
87.4t (30), 81.6dd (30,38), 8.5dd (30,38)
95.2t (22), 85.0dd (22,36), 18.8dd (22,36)
91.4dd (34,48), 87.0dd (34,37), 8.8dd (37,48)
7a
7b
7d
7l
140.1s
139.0s
124.9s
139.5t (25), 136.7t (25), 135.3t (25)
139.5t (27), 136.7d (27)
7m
observations of Wild and co-workers on related systems.17 The
resultant phosphido complex attains an 18-electron configuration
at iron (inhibiting π-basic behavior) and thus supporting a
σ-bonded phosphido ligand which retains nucleophilic character.
The available lone pair may project toward or away from the
acceptor orbitals of the vinyl group, as shown schematically in
Figure 2. The subsequent coupling chemistry to form the linear
P3 intermediates 3a-d and the final macrocycles 4a-d is only
possible when the lone pair of the transient phosphide projects
away from the Cp ligand. This extends to the transformation of
the linear triphosphorus species (3) to the macrocyclic product,
and of the four possible diastereoisomers of 3a-d that relate
as two enantiomeric pairs, only one of these pairs can form.
The presence of a single AMX pattern in the 31P{1H} NMR
spectra of 3a-d confirms this, with only one enantiomer (or
more likely enantiomeric pair) of the complexes being detected
in solution. The selection is kinetic in origin (although the
adopted structures may be preferred thermodynamically), as
shown in Figure 2. The final ring closure to form the macrocycle
is similarly constrained by the selection shown in the figure, so
that for all the isolated complexes of [(η5-CpR)Fe(9-aneP3)]+,
the substituents at the phosphorus atoms (H, Ph, vinyl, etc.)
project toward the Cp fragment.
Although compounds of the type [(η5-CpR)Fe(9-aneP3H2-
C2H3)]+, 4, were the predominant species observed in solution
on completion of the reactions, insoluble deposits of an unknown
nature were often formed, and these contribute to the modest
isolated yields of products after cyclization. Generally, these
precipitates were more prevalent in mixtures that required long
reaction times and are likely to be the result of unwanted
intermolecular couplings, and since the final macrocycle product
contains a pendant vinyl function, this could occur between
intermediate as well as product molecules. The macrocyclic
complexes 4a-d were isolated as orange-yellow solids that
were readily recrystallized from alcohols and are air-stable
indefinitely in the solid state but air-sensitive in solution.
Ethanolic solutions darken as a result of partial decomposition,
whereas in hydrochlorocarbons, the P-H functions are chlori-
nated; this latter reaction is accelerated upon addition of aqueous
base (NaOH).
The 31P{1H} NMR spectra (Table 1) reveal a dependence of
both δP and 2JP-P on the nature of the Cp donor. The coordinated
1,2-dpe in the monoacetonitrile complexes 1a-d resonates
between 0 and 8 ppm, ∼130 ppm downfield of the signal for
the uncoordinated diphosphine, but is typical of formation of a
5-membered chelate.18 The 31P NMR chemical shifts for 1a-c
are similar (δP 0.5-3.0 ppm), whereas for the Me5Cp derivative,
(17) Bader, A.; Kang, Y. B.; Pabel, M.; Pathak, D. D.; Willis, A. C.; Wild, S.
B. Organometallics 1985, 4, 1434.
Figure 2. Diastereomeric possibilities and possible reaction pathways for
the formation of the linear intermediate 3a from 2a. The second ring
formation (macrocycle formation) to give 4a is governed similarly.
(18) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of Transition Metal
Complexes; Springer-Verlag: Berlin, 1979.
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J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3821

A R T I C L E S
Edwards et al.
1d, the downfield shift is greater (δP 7.0 ppm); this is
presumably a consequence of the electronic differences within
the series of CpR donors. The complexes 2a-d show the
expected doublet (RPH2) and triplet [P(C2H3)3] in their 31P{1H}
NMR spectra, and the absolute difference in chemical shift
between the two signals (∆[δ1 - δ2]) and 2JP-P decreases along
the series Cp > Me3SiCp > (Me3Si)2Cp > Cp*. This trend
extends to the complexes 3a-d and 4a-d. Furthermore,
although the coordinated trivinylphosphine resonates at δ 50
( 2 ppm in 2a-d, the vinyl bearing phosphine resonates at a
higher field (δP 117.0 ppm) in 4d than in 4a-c (δP 126-131
ppm). This is even more pronounced in the perethylated
tritertiary phosphine complexes [(η5-CpR)Fe(9-aneP3Et3]+, 7a,b,d
(Table 1). A possible reason is that increased steric compression
about the metal center in 2d forces the Fe-P(vinyl) bond to
lengthen, resulting in the somewhat anomalous δP value; this
relative bond lengthening is observed in the crystal structure
(see below).
Figure 3. Ortep representation of the structure of 4c. Ellipsoids are drawn
at 30% probability. Selected bond lengths (Å) and angles (°): Fe2-P4 )
2.156(3), Fe2-P5 ) 2.168(3), Fe2-P6 ) 2.174(3), Fe2-C20 ) 2.119(10),
Fe2-C21 ) 2.094(10), Fe2-C22 ) 2.089(11), Fe2-C23 ) 2.113(10),
Fe2-C24 ) 2.090(10), P4-Fe2-P5 ) 85.73(12), P4-Fe2-P6 ) 84.98(12),
P5-Fe2-P6 ) 86.25(12).
In common with the 31P{1H} NMR data, the η5-Cp* deriva-
1
tive 4d shows some significant differences in its H NMR
spectrum with respect to 4a-c. Most notable is the relative
chemical shift of the PH protons, which resonate at δH 5.55
ppm in the spectrum of 4d as opposed to 6.24 ( 0.05 ppm for
4a-c. Steric encumbrance at the secondary phosphines is not
expected to be large, and it may be that these differences in δH
(PH) are mainly electronic in origin as (presumably) are the
variations in the 31P spectra (see above). Where resolvable, the
Cp ring protons of the 1a f 7a series appear as quartets in the
1H NMR spectra with a JP-H coupling of ∼1.5 Hz. The
methylene carbons in the macrocycle give three distinct mul-
tiplets in the 13C NMR spectra of complexes 4a-d, suggesting
pairwise equivalence and hence a plane of symmetry through
the P-vinyl phosphorus bisecting the -HPCH2CH2PH- carbon-
carbon bond and therefore rapid conformational inversion in
the 5-membered chelate rings. All the complexes of type 4
containing secondary phosphine donors show a weak but
characteristic ν(P-H) stretch in their infrared spectra at ap-
the C24 carbon of the Cp ring and the vinyl function occupies
the space between the two Me3Si groups. Unsurprisingly, the
Fe-C(Si) bond lengths are the longest of the Fe-C bonds, and
the C-Si vectors are bent ∼10° out of the C5 plane. These
distortions of the silyl groups out of the C5 plane of the
cyclopentadienyl ligand, coupled with the Fe-P-Cvin bond
angles being expanded to an average of 122.8°, are evidence
for the steric compression discussed above. The vinyl group is
located on the same side of the P3 plane as the (Me3Si)2Cp unit,
an orientation required by the pathway for ring formation
detailed in Figure 2.
9aneP3 Derivatives from Template Reactions of Phenyl-
(2-phosphinoethyl)phosphine and Trivinylphosphine. As
described above, the cyclization chemistry is sensitive to the
nature of the peripheral substituents on the CpR unit with greater
rates being realized with increased bulk at these positions. In
the synthesis of nitrogen macrocycles by the Richman-Atkins
method,21 it is well-known that bulky substituents on the
nitrogens of acyclic precursor amines helps facilitate ring closure
due to the steric influence of the substituents. In view of this,
it was of interest to see what effect (if any) the introduction of
a substituent at one of the primary phosphines of 1,2-diphos-
phinoethane (to generate a mixed primary/secondary bidentate
phosphine) had on the subsequent cyclization chemistry. To this
end, phenyl(2-phosphinoethyl)phosphine, Phdpe, was employed
with the most effective of the CpRFe+ templates, that is, the
silylated cyclopentadienyl iron(II) fragments, and trivinylphos-
phine. The precursor complexes [(η5-Me3SiCp)Fe(Phdpe)-
(MeCN)]PF6, 1e, and [{η5-(Me3Si)2Cp}Fe(Phdpe)(MeCN)]PF6,
1f, were readily prepared in the same manner as their 1,2-dpe
analogues (1a-d), and they were isolated as a mixture of two
diastereomeric pairs of enantiomers: Fe(R), P(R)/Fe(S), P(S),
and Fe(S), P(R)/Fe(R), P(S) (see Figure 2). Reaction of
complexes 1e,f with trivinylphosphine gives rise to the diphos-
phine/monophosphine complexes [(η5-CpR)Fe(Phdpe)(tvp)]PF6,
2e (R ) Me3Si), and [{η5-(Me3Si)2Cp}Fe(Phdpe)(tvp)]PF6, 2f,
proximately 2360 ( 20 cm-1
.
The complex [{η5-(Me3Si)2Cp}Fe(9-aneP3H2C2H3]BF4, 4c,
crystallizes in the P21/c space group with two distinct molecules
in the asymmetric unit. The structure of one of the complex
cations of 4c is shown in Figure 3. The iron(II) center is pseudo-
octahedral with the usual distortions due to the small “bite” of
the carbons in the Cp ring. The macrocycle is facially
coordinated with Fe-P bond lengths averaging 2.17 Å (there
is little difference between Fe-PH and Fe-Pvinyl) and P-Fe-P
angles averaging 85.5°. These values compare with those of
1,2-C6H4(PMePh)2 in [(R*,R*),(R*)]-(()-[(η5-C5H5)Fe{1,2-
19
C6H4(PMePh)2}(PHMePh)]PF6 (Fe-P ) 2.176, 2.183 Å;
P-Fe-P ) 86.3°) and the 11aneP2N macrocycle in [(η5-Cp)-
Fe(meso-cis-2,10-diphenyl-6-aza-2,10-diphenylbicyclo[9.4.0]-
pentadeca-11(1),12,14 triene)]I (Fe-P ) 2.177, 2.193 Å;
P-Fe-P ) 86.9°).20 The bond lengths are shorter and the angles
tighter, however, than those in the related [(η5-Cp)Fe(12-
aneP3Et3)]+ complexes.13c When the structure of the bis-
(trimethylsilyl) Cp, 4c, complex is viewed down the vector
connecting the centroid of the Cp ring to the iron, it is evident
that the phosphorus donor bearing the vinyl group lies below
(19) Crisp, G. T.; Salem, G.; Wild, S. B. Organometallics 1989, 8, 2360.
(20) Liu, C.-Y.; Cheng, M.-C.; Peng, S.-M.; Liu, S. T. J. Organomet. Chem.
1994, 468, 199.
(21) Richman, J. E.; Atkins, T. J. Am. Chem. Soc. 1974, 96, 2268.
9
3822 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Template Synthesis of 1,4.7-Triphosphacyclononanes
A R T I C L E S
also as a pair of diastereomers. It is clear from Figure 2 that
the Fe(R), P(R)/Fe(S), P(S) diastereomeric pair will not form
the desired 9-aneP3HPhC2H3 compounds unless inversion occurs
at the P(Ph) center. The chemistry highlighted in Figure 2 relates
to the situation where the secondary phosphine reacts to form
the first 5-membered chelate; that is, to produce the linear
4-phenyl-1,4,7-triphosphanonane intermediate, the terminal
primary phosphine (phosphide) of this intermediate is then
available to react with one of the remaining vinyl functions to
give the macrocyclic complex in a manner akin to that observed
for 3a-d. A second route involving the initial reaction of the
primary phosphine (phosphide) to give the 1-phenyl-1,4,7-
triphosphanonane intermediate is also possible. The intermediate
from this route has a stereogenic terminal secondary phosphine
which can only react to form the macrocyclic complexes [(η5-
CpR)Fe(9-aneP3HPhC2H3)]PF6, 4e,f, when the orientation is right
(cf. Figure 2 and the associated discussion for the 4a-d
systems). 31P{1H} NMR analysis of the reaction mixtures during
the conversions 2e,f f 4e,f suggests that both routes operate.
The cyclization reaction for 2e and 2f is considerably slower
than that for the related systems 2b and 2c, and the yields of
the desired complexes 4e and 4f are lower. As the axial
orientation of nonannular groups is not possible in the 9-aneP3
complexes, the resultant macrocylic complexes 4e,f are formed
as a mixture of only two enantiomers. These are characterized
in their 31P{1H} NMR spectra by three distinct triplets for each
of the unique phosphorus centers; two tertiary and one secondary
phosphine is confirmed in the 31P NMR spectra. All the
phosphorus atoms and the iron(II) center are stereogenic, and
the two trimethylsilyl groups of the (Me3Si)2Cp unit in [η5-
1,3-bis(trimethylsilyl)cyclopentadienyl](1-phenyl-4-vinyl-1,4,7-
triphosphacyclononane)iron(II) hexafluorophosphate, 4f, are
diastereotopic; these are observed as distinct singlets at δH 0.07
and 0.05 ppm in the 1H NMR and δC 0.7 and at 0.5 ppm in the
13C{1H} NMR spectra of the complex. Similarly, all the
cyclopentadienyl protons are inequivalent and give rise to three
Figure 4. Possible reaction pathways and diastereomeric products in the
reactions involving the divinylaryl(alkyl)phosphines.
(see above). It remained of interest to see what effect changing
the site of the phenyl substituent from the diphosphine to the
monophosphine would have on the subsequent coupling chem-
istry. Whereas the cyclization was anticipated to be slow for
the reactions employing phenyl(2-phosphinoethyl)phosphine and
trivinylphosphine, it was originally doubted whether divinyl-
(alkyl/aryl)phosphines would give any isolable yield of mac-
rocyclic complex. The distinction between the cyclization
chemistry here and that for the Phdpe/tvp complement is that,
for the latter, linear intermediates with one terminal primary
phosphine and a second terminal phosphorus bearing two vinyl
functions are accessible (through the initial coupling of the
secondary phosphine of Phdpe) enabling complete cyclization
akin to reactions using unsubstituted 1,2-dpe and tvp. This is
not the case for divinyl(alkyl/aryl)phosphines which necessarily
go through linear intermediates with only one vinyl function
on a terminal phosphorus. This will lead to stereochemical
relationships between the terminal phosphines which may limit
complete cyclization (Figure 4). The formation of the first
5-membered chelate to give 3h-j generates two stereogenic
phosphorus centers. When the Psec donor has the S configuration,
macrocycle formation is only possible when Ptert has the R
absolute configuration. Likewise, if Psec is R, then Ptert must be
1
distinct resonances in the H and 13C{1H} NMR spectra of 4f.
In an effort to introduce some diastereoselectivity into the
macrocycle formation, the chiral Cp ligand (+)-neomenthyl-
cyclopentadiene, (+)-neoMenCp, was employed. Following
related literature examples,14 the complex [{(+)-neoMenCp}-
Fe(MeCN)(Phdpe)]BF4, 1g, was obtained as an approximately
equimolar mixture of four diastereomers; because of the
predefined chirality of the (+)-neoMenCp, there is no enantio-
meric relationship between any of the diastereomers of 1g. The
subsequent cyclization chemistry with Phdpe and tvp was less
efficient with this template with respect to the silylated
cyclopentadienyl templates, with the consequence that [{(+)-
neoMenCp}Fe(9-aneP3HPhC2H3)]BF4, 4g, was obtained in low
yield. The complex 4g is formed as an equimolar mixture of
the two possible diastereoisomers which, unlike the case for
the enantiomeric pair of 4e,f, have distinct NMR spectra as
detailed in the Experimental Section and Table 1; thus the chiral
auxiliary did not induce any enantioselectivity in the cyclization
reaction under our conditions.
S in order for macrocyclization to occur (Figure 4). The Psec
Ptert combinations S/S and R/R preclude formation of the
macrocycle. The combinations R(Psec)/S(Ptert) and S(Psec)/R(Ptert
/
)
are enantiomers, as are the R,R and S,S pair; the relationship
between the two sets is diastereomeric. Therefore, two sets of
peaks would be expected in the 31P{1H} NMR spectrum (one
for the R,S/S,R pair and one for the S,S/R,R pair) if more than
one diastereomer of 3h-j were present. Heating a solution of
[{η5-(Me3Si)2Cp}Fe(1,2-dpe){PPh(C2H3)2}]PF6, 2h, in chlo-
robenzene to 80 °C for several days gave no intermediate 3h
or macrocycle complex [{η5-(Me3Si)2Cp}Fe(9-aneP3H2Ph)]PF6,
4h, as determined by 31P{1H} NMR spectroscopy. When the
reaction was repeated in the presence of 2 molar equiv of
triethylamine, the distinctive AMX pattern of the part coupled
9aneP3 Derivatives from Template Reactions of 1,2-
Diphosphinoethane and Divinylalkyl(aryl)phosphines. All the
reactions discussed thus far have employed trivinylphosphine,
and it has been shown that replacing a hydrogen in 1,2-dpe with
a phenyl group reduces the efficiency of the macrocyclization
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3823

A R T I C L E S
Scheme 2
Edwards et al.
linear acyclic triphosphine intermediate 3h was observed within
several hours. However, only one set of doublets of doublets
was observed for each distinct phosphorus center, indicating
that only a single isomer (or, more likely, one enantiomeric pair)
of 3h is formed. Further heating leads to complete conversion
of 2h to 3h with concomitant formation of [{η5-(Me3Si)2Cp}-
Fe(9-aneP3H2Ph)]PF6, 4h. After 3 days, the reaction is complete
and 4h is isolated in 29% yield. The fact that all the linear
intermediate (3h) is converted to the macrocycle product 4h
confirms the assignment of the former as the R,S/S,R mixture.
The rate of cyclization is much slower than the analogous
reaction with trivinylphosphine (2c to 4c), and consequently
yields are lower as deleterious intermolecular side reactions
compete with the desired coupling. The observation of only one
enantiomeric pair of 3h may reflect a preferred orientation of
the divinylphenylphosphine in 2h, that is, A in Figure 4, which
is, fortunately, an orientation that favors macrocyclization. The
complexes 4i and 4j were prepared similarly, again in low to
modest yield. To assess the efficiency or otherwise of radical
induced coupling, [(η5-Cp*)Fe(1,2-dpe)(dvpp)]+ and [(η5-Cp*)-
Fe(1,2-dpe)(dvbp)]+, where dvpp is divinylphenylphosphine and
dvbp is divinylbenzylphosphine, were cyclized in the presence
of AIBN (no base), but under these conditions, intermolecular
coupling predominates and the desired compounds are isolated
in very low yield (5%).
Further Functionalization of Secondary Phosphine Com-
plexes of Type 4. For complexes of 12-aneP3H3 macrocycles
coordinated to Cr(0) or Mo(0), it is possible to convert the PH
groups to tertiary phosphines by either a stepwise process of
deprotonation and electrophilic alkylation or by radical-induced
hydrophosphination. In preliminary studies, we have shown that
deprotonation and alkylation can lead to 1,4,7-triethyl-1,4,7-
triphosphacyclononane (9-aneP3Et3) complexes of iron(II).13b
There are two possible routes for the formation of the 1,4,7-
triethyl-1,4,7-triphosphacyclononane complexes (7a-d) from
the 1-vinyl derivatives (4a-d) as indicated in Scheme 2.
The first, which has been used successfully for the preparation
of [{η5-Cp*}Fe(9-aneP3Et3)] BF4, 7d,13b involves hydrogenation
of the vinyl group proceeded by alkylation of the secondary
phosphine functions with KOtBu/EtBr. This is the preferred
route for the pentamethyl- and trimethylsilyl-substituted cyclo-
pentadienyl complexes. However, the unsubstituted Cp deriva-
tive, with a single vinyl function (4a), is poorly soluble in
ethanol (the solvent of choice for the hydrogenation), resulting
in slow rates and/or the need for large volumes of solvent. For
this complex, the second route, whereby the secondary phos-
phines in [(η5-Cp)Fe(9-aneP3H2C2H3)]BF4, 4a, are ethylated to
give the 1,4-diethyl-7-vinyl derivative 6a which is subsequently
hydrogenated to the 1,4,7-triethyl species 7a, is preferred as
[(η5-Cp)Fe(9-aneP3Et2C2H3)]BF4, 6a, is much more soluble in
ethanol than is 4a. This route is not the first choice for all the
complexes as the reactive vinyl group can interfere with the
alkylation, and in the synthesis of 6a, the amount of added base
must be carefully controlled in order to prevent dimerization
of 4a by an intermolecular Michael-type addition. The trim-
ethylsilyl groups in 4b, 4c, 5b, and 5c are unstable under the
basic conditions required for ethylation. Thus, attempts to isolate
[(η5-{Me3Si}2Cp)Fe(9-aneP3Et2C2H3)]BF4, 6c, were unsuccess-
ful as partial loss of one or both Me3Si functions from the Cp
ring was observed with the formation of a mixture of [(η5-
Cp)Fe(9-aneP3Et2C2H3)]BF4 (6a) and [(η5-Me3SiCp)Fe(9-aneP3-
Et2C2H3)]BF4 (6b). Furthermore, this loss is accompanied by
partial reduction of the vinyl group of the resultant 6a/6b to
give variable amounts of [(η5-Cp)Fe(9-aneP3Et3)]BF4, 7a, and
[(η5-Me3SiCp)Fe(9-aneP3Et3)]BF4, 7b, and so an overall mixture
of 6a, 6b, 7a, and 7b was obtained. Fortunately, both like pairs
6a/7a and 6b/7b could be isolated and the mixtures hydroge-
nated to give reasonable yields of pure 7a and 7b.
Although the extent of desilylation was less for the monosi-
lylcyclopentadienyl complex [(η5-Me3SiCp)Fe(9-aneP3H2C2H3)]-
BF4, 4b, with respect to the disilyl derivative [(η5-{Me3Si}2Cp)-
Fe(9-aneP3H2C2H3)]BF4, 4c, complex mixtures were still observed
and 6b was isolated in only modest yield. These Me3Si
eliminations were also observed on ethylating [(η5-Me3SiCp)-
Fe(9-aneP3H2Et)]BF4, 5b, and [(η5-{Me3Si}2Cp)Fe(9-aneP3H2-
Et)]PF6, 5c. Although careful control of reaction temperature
and amount of added base gave good yields of the perethylated
complex [(η5-Me3SiCp)Fe(9-aneP3Et3)]BF4, 7b, the analogous
(Me3Si)2Cp complex, 7c, was not obtained pure. Efforts to
obtain 7c by ethylation of 5c using Et3N and EtBr were only
partly successful; although no desilylation was observed,
bromination of the secondary phosphines did occur as a
9
3824 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Template Synthesis of 1,4.7-Triphosphacyclononanes
A R T I C L E S
conditions or bromine in dichloromethane and water in a
modification of the liberation conditions of Stelzer,22 the free
macrocycle was isolated as the trioxide, 8 (Scheme 2). Use of
either liberation technique results in excellent recovery of
9-aneP3(O)3Et3, although the bromine method is the preferred
one. The resultant 9-aneP3(O)3Et3 is a hygroscopic white solid
that is freely soluble in water, sparingly soluble in alcohols,
and insoluble in other common organic solvents. The 31P{1H}
NMR spectrum consists of a singlet at δP ) 65.2 ppm
confirming the all syn arrangement of the PdO functions as
indicated in Scheme 1. The chemical shift is similar to those
for related P4 macrocycle oxides.22 1H and 13C NMR spectra
are consistent with the proposed structure. A strong absorption
at 1145 cm-1 in the infrared spectrum is assigned to the ν(PdO)
stretch. It is of interest to note that the mass spectrum of the
trioxide only gave a peak for [9-aneP3(O)3Et3 + M+] where M
) Li, Na, suggesting a high affinity of the compound for hard
metal ions. To date, all efforts to reduce the trioxide to the
phosphine using LiAlH4 and PhSiH3 have proved fruitless,
possibly due to the very poor solubility of the compound in
appropriate solvents. Work is continuing on the development
of methods for the reduction of the trioxide and/or release of
the macrocycle from the template without ligand oxidation.
In conclusion, a general method for the synthesis of 9-aneP3
macrocycles using CpFe(II) units as templates has been
established. The rate of formation of the macrocycles is
dependent on the nature and position of the substituents on the
Cp ring and the phosphorus donors. The triethyl macrocycle
has been released from the template by oxidation using H2O2
to give the trioxo derivative. We are currently examining the
stereoselective reduction of the 9-aneP3(O)3Et3 compound to
obtain the free phosphine with a view to investigating the
chemistry of this and related systems with a range of metal ions.
Figure 5. Ortep representation of the structure of 7b. Ellipsoids are drawn
at 30% probability. Selected bond lengths (Å) and angles (°): Fe1-P1 )
2.178(4), Fe1-P2 ) 2.196(5), Fe1-P3 ) 2.153(4), Fe1-C1 ) 2.140(14),
Fe1-C2 ) 2.114(16), Fe1-C3 ) 2.088(15), Fe1-C4 ) 2.090(16), Fe1-
C5 ) 2.071(16); P1-Fe1-P2 ) 81.86(17), P1-Fe1-P3 ) 86.47(18), P2-
Fe1-P3 ) 87.25(18), Fe1-P1-C19 ) 120.2(6), Fe1-P2-C15 ) 123.0(6),
Fe1-P3-C17 ) 123.1(7).
competing reaction and it proved difficult to separate the desired
complex 7c from the [(η5-{Me3Si}2Cp)Fe(9-aneP3Et2Br)]PF6
byproduct. The desilylation extended to the complex [(η5-Me3-
SiCp)Fe(9-aneP3HEtPh}]PF6, 5e, which, upon deprotonation and
subsequent alkylation with 1-bromopentane, eliminated the
trimethylsilyl fragment to give [(η5-Cp)Fe(9-aneP3EtPhC5H11)]-
PF6, 7l. In addition, when complex [(η5-{Me3Si}2Cp)Fe(9-
aneP3H2Et)]PF6, 5c, was treated with an excess of potassium
tert-butoxide, and subsequently reacted with >2 molar equiv
of 1-bromopentane, only [(η5-Cp)Fe(9aneP3Et{C5H11}2)]PF6,
7m, was isolated. The tritertiary complexes 6a-c,k and 7a,b,l
are all bright yellow, air-stable crystalline solids that retain their
stability to air and moisture when in solution. The symmetrical
9-aneP3Et3 derivatives (7a,b,d) are soluble in hydrochlorocar-
bons, and alcohols and may be crystallized from these with or
without additional solvents. The structure of [(η5-Me3SiCp)Fe-
(9-aneP3Et3)]+ (7b) is shown in Figure 5.
The structure is as expected with a pseudo-octahedral iron
atom facially capped by the Cp ligand and the P3 macrocycle.
The Fe-C(SiMe3) bond is significantly longer [2.14(1) Å] than
the remainder [av. 2.09(2) Å] as is the Fe-P2 bond: 2.196(5)
Å compared to 2.153(4) and 2.178(4) for the other two. The
longest Fe-P bond is comparable to those of 7d (av. 2.194 Å)
and to the phosphorus whose ethyl substituent is in closest
contact with the bulky Me3Si group on the Cp fragment. The
P1-Fe1-P2 angle is the smallest of the P-Fe-P angles due,
presumably, to the steric influence of the trimethylsilyl group
on the two phosphorus atoms. The average Fe-P-Cethyl angle
is again expanded to 122.6°, reflecting the steric compression
in the complex. The average of the Fe-P bonds is longer here
at 2.175 Å than in complex 4c. In addition, the C-Si bond is
bent 14° out of the C5 plane of the Cp ring, appreciably more
than in [(η5-{Me3Si}2Cp)Fe(9-aneP3H2C2H3)]+, 4c, or for the
methyl groups in [(η5- Cp*)Fe(9-aneP3Et3)]+, 7d.
Experimental Section
The complexes were synthesized under nitrogen using standard inert
atmosphere (Schlenk) techniques. The tertiary macrocycle complex salts
are indefinitely stable in air in the solid state and in solution; solutions
of macrocycle complexes containing secondary phosphines were
manipulated and stored under nitrogen. All solvents were freshly
distilled from sodium (toluene and anisole) or calcium hydride
(acetonitrile and 1,2-dichloroethane) under nitrogen before use. The
31P NMR spectra were recorded on JEOL FX90Q, Bruker AM360, and
JEOL Eclipse 300 spectrometers operating at 36.2, 145.1, and 121.7
1
MHz, respectively, and referenced to 85% H3PO4 (δ ) 0 ppm). H
(400.13 or 300 MHz) and 13C (100 or 75.6 MHz) NMR spectra were
obtained on Bruker DPX400 and JEOL Eclipse 300 spectrometers and
are referenced to tetramethylsilane (δ ) 0 ppm). Infrared spectra were
recorded as KBr disks on a Nicolet 510 FT-IR spectrophotometer. Mass
spectra were obtained on a VG Fisons Platform II spectrometer at
Cardiff or through Warwick Analytical Service Ltd. Microanalyses were
performed within the School of Chemistry at Cardiff or by Warwick
Analytical Service Ltd. 1,2-Bis(phosphino)ethane,23 phenyl(2-phosphi-
noethyl)phosphine,24 trivinylphosphine,25 [{η5-(Me3Si)Cp}Fe(CO)2]2,26
[{η5-(Me3Si)2Cp}Fe(CO)2]2,27 and [{(+)-neomenthyl)Cp}Fe(CO)2]2
28
(22) Lebbe, T.; Machnitzki, P.; Stelzer, O.; Sheldrick, W. S. Tetrahedron 2000,
56, 157.
(23) Taylor, R. C.; Walters, D. B. Inorg. Synth. 1973, 14, 10.
(24) King, R. B.; Cloyd, J. C. J. Am. Chem. Soc. 1975, 97, 46.
(25) Kaesz, H. D.; Stone, F. G. A. J. Org. Chem. 1959, 24, 635.
(26) Berryhill, S. R.; Clevenger, G. L.; Burdurlu, F. Y. Organometallics 1985,
4, 1509.
Liberation of 9-aneP3Et3 as the Trioxide. When 7b (or 7a)
was treated with aqueous hydrogen peroxide under acidic
(27) Clark, J. T.; Killian, C. M.; Luthra, S.; Nile, T. A. J. Organomet. Chem.
1993, 462, 247.
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3825

A R T I C L E S
Edwards et al.
were prepared as described. All other chemicals were of reagent grade
and were used as supplied unless otherwise stated. Complexes 1d, 4d,
5d, and 7d were synthesized by the reported methods.13b
g, 1.97 mmol) and 1,2-diphosphinoethane (0.2 mL, 2.1 mmol). After
removing the solvent, the residue was triturated with diethyl ether to
give 1c as an orange solid. Yield ) 0.81 g (70%). 31P{1H} NMR
1
(Acetonitrile)dicarbonyl(η5-trimethylsilylcyclopentadienyl)-
iron(II) tetrafluoroborate. This compound was prepared from [{η5-
(Me3Si)Cp}Fe(CO)2]2 (1.00 g, 2.01 mmol) and ferrocenium tetrafluo-
roborate using the method of Astruc.14 Large golden-brown crystals
were grown from acetone/diethyl ether at -30 °C. Yield ) 1.32 g
(CDCl3, 36.23 MHz): δ ) 1.5. H NMR {(CD3)2CO, 300 MHz}: δ
1
) 5.50 (d br, 2H, PH2, JPH ) 343 Hz), 5.32 (s, 1H, Cp), 5.05 (d br,
2H, PH2, 1JPH ) 341 Hz), 4.71 (s, 2H, Cp), 2.27 (s, 3H, CH3CN), 2.20
(br, 2H, CH2), 1.94 (br, 2H, CH2), 0.28 (s, 18H, SiCH3). Reproducible
elemental analysis was not possible for this complex due to excessive
decomposition by loss of acetonitrile prior to combustion. IR (KBr):
2330m (νPH), 2269m (νCN).
1
(87%). H NMR (CDCl3, 400 MHz): δ ) 5.63 (s, 2H, Cp), 5.42 (s,
2H, Cp), 2.41 (s, 3H, CH3CN), 0.34 (s, 9H, SiCH3). Elemental analysis
calcd for C12H16NSiO2BF4Fe: C, 38.22; H, 4.29; N, 3.72. Found: C,
37.9; H, 4.2; N, 3.5. IR (KBr): 2328w (νCN), 2066, 2021vs (νCO).
(Acetonitrile)dicarbonyl{η5-1,3-bis(trimethylsilyl)cyclopentadienyl}-
iron(II) hexafluorophosphate. This compound was prepared as above
using [{η5-(Me3Si)2Cp}Fe(CO)2]2 (1.00 g, 1.56 mmol) and ferrocenium
hexafluorophosphate and obtained as a yellow microcrystalline solid
by crystallization from from acetone/diethyl ether mixtures. Yield )
1.30 g (82%). 1H NMR {(CD3)2CO, 300 MHz}: δ ) 5.53 (s, 1H, Cp),
5.40 (s, 2H, Cp), 2.36 (s, 3H, CH3CN), 0.29 (s, 18H, SiCH3). Elemental
analysis calcd for C15H24NSi2O2PF6Fe: C, 35.50; H, 4.78; N, 2.76
Found: C, 35.1; H, 4.7; N, 2.6 IR (KBr): 2316w (νCN), 2076, 2036vs
(νCO).
(Acetonitrile)dicarbonyl{η5-(+)-neomenthylcyclopentadienyl}-
iron(II) hexafluorophosphate. This compound was prepared from
[{η5-(+)-neomenthylCp}Fe(CO)2]2 (1.00 g, 1.58 mmol) using a method
similar to those above. The pure compound was obtained after two
recrystallizations from acetone/diethyl ether mixtures at -30 °C. Yield
) 0.90 g (57%). 1H NMR (CD2Cl2, 400 MHz): δ ) 5.45 (s, 1H, Cp),
5.24 (s, 1H, Cp), 5.19 (s, 1H, Cp), 5.14 (s, 1H, Cp), 2.80 (s br, 1H),
2.29 (s, 3H, CH3CN), 1.8-0.8 (m, 9H), 0.86 (d, 3H, 5.0 Hz), 0.85 (d,
3H, 5.0 Hz), 0.72 (d, 3H, 6.2 Hz). Elemental analysis calcd for C19H26-
NO2PF6Fe: C, 45.52; H, 5.24; N, 2.79. Found: C, 45.1; H, 5.2; N,
2.5. IR (KBr): 2336w (νCN), 2061, 2024vs (νCO).
(Acetonitrile)(η5-cyclopentadienyl)(1,2-diphosphinoethane)-
iron(II) hexafluorophosphate, 1a. A solution of [(η5-Cp)Fe(η6-C6H6)]-
PF6 (1.00 g, 2.91 mmol) and 1,2-diphosphinoethane (0.30 mL, 3.1
mmol) in acetonitrile (50 mL) was irradiated for 12 h with a 100 W
tungsten lamp. The solvent was subsequently removed and the resultant
residue crystallized from hot tetrahydrofuran/acetonitrile to give
complex 1a as orange-red crystals. Yield ) 1.00 g (85%). 31P{1H}
NMR (CDCl3, 36.23 MHz): δ ) 0.5. 1H NMR {(CD3)2CO, 300
MHz}: δ ) 5.67 (d, 2H, PH2, 1JPH ) 356 Hz), 4.92 (d, 2H, PH2, 1JPH
) 340 Hz), 4.58 (s, 5H, Cp), 2.29 (s, 3H, CH3CN), 2.05 (br, 4H, CH2).
Elemental analysis calcd for C9H16NP3F6Fe: C, 26.95; H, 4.03; N, 3.49.
Found: C, 26.6; H, 3.8; N, 3.1. IR (KBr): 2352, 2317m (νPH), 2265m
(νCN).
The BF4 salt was prepared as follows. A solution of η5-(Me3-
-
Si)2CpFe(CO)2I (0.50 g, 1.12 mmol) and AgBF4 (0.22 g, 1.12 mmol)
in acetonitrile (50 mL) was stirred in the absence of light for 24 h.
After filtering, the solution was diluted 2-fold and the BF4- salt prepared
-
and isolated in an analogous manner to that of the PF6 salt above.
Yield ) 0.39 g (72%). Spectroscopic data as above.
(Acetonitrile)(η5-trimethylsilylcyclopentadienyl){phenyl-
(2-phosphinoethyl)phosphine}iron(II) hexafluorophosphate, 1e. This
compound was prepared as for 1b but using phenyl(2-phosphinoethyl)-
phosphine and [{η5-(Me3Si)Cp}Fe(CO)2(CH3CN)]PF6. Removal of the
solvent gave a red solid which was washed with diethyl ether to remove
residual phosphine. Yield ) 1.25 g (99%). 31P{1H} NMR (CD3CN,
121.7 MHz): δ ) 74.8 (d, 33 Hz), 63.8 (d, 36 Hz), 3.7 (d, 36 Hz), 2.7
(d, 33 Hz). 1H NMR (CD3CN, 300 MHz): δ ) 7.8-7.2 (m, 5H, Ph),
6.5-3.6 (m, 7H, PH, PH2, Cp), 2.6-1.6 (m, 7H, CH2, CH3CN), 0.24
and 0.20 (2 × s, 9H, SiCH3). Elemental analysis calcd for C18H28-
NSiP3F6Fe: C, 39.34; H, 5.10; N, 2.55. Found: C, 40.4; H, 5.5; N,
2.1. Analytical data were variable, reflecting the instability of the
compound with respect to loss of CH3CN; the data listed here are the
closest to required values obtained. IR (KBr): 2314m (νPH), 2262w
(νCN).
(Acetonitrile){η5-1,3-bis(trimethylsilyl)cyclopentadienyl}{phenyl-
(2-phosphinoethyl)phosphine}iron(II) hexfluorophosphate, 1f. This
compound was prepared as for 1c but using phenyl(2-phosphinoethyl)-
phosphine. Removal of the solvent gave a red solid which was washed
with diethyl ether to remove residual phosphine. Yield ) 1.09 g (89%).
31P{1H} NMR (CD3CN, 121.7 MHz): δ ) 72.5 (d, 36 Hz), 61.4 (d,
1
33 Hz), 3.8 (d, 33 Hz), 1.6 (d, 36 Hz). H NMR (CD3CN, 300 MHz):
δ ) 7.7-7.3 (m, 5H, Ph), 6.7-4.3 (m, 6H, PH, PH2, Cp), 2.5-1.6 (m,
7H, CH2, CH3CN), 0.33, 0.16, 0.14 and 0.13 (4 × s, 18H, SiCH3).
Reproducible elemental analytical data were not obtained for this
complex due to excessive decomposition by loss of acetonitrile prior
to combustion. IR (KBr): 2336m (νPH), 2269w (νCN).
(Acetonitrile){η5-(+)-neomenthylcyclopentadienyl}{phenyl(2-
phosphinoethyl)phosphine}iron(II) tetrafluoroborate, 1g. A solution
of [{η5-(+)-neomenthylCp}Fe(CO)2(CH3CN)]PF6 (1.00 g, 2.0 mmol)
and phenyl(2-phosphinoethyl)phosphine (0.35 mL, 2.06 mmol) in
acetonitrile (100 mL) was irradiated for 12 h with a Hanovia 125 W
UV lamp. The solvent was subsequently removed in vacuo to give a
red solid which was washed once with diethyl ether, dried in vacuo,
and used for the subsequent reactions without further purification. Yield
) 0.90 g (82%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 75.4 (d, 33
Hz), 74.7 (d, 33 Hz), 63.8 (d, 33 Hz), 63.6 (d, 33 Hz), 3.9 (d, 33 Hz),
3.1 (d, 33 Hz), 2.3 (d, 33 Hz), 2.2 (d, 33 Hz). Reproducible elemental
analytical data were not obtained for this complex due to excessive
decomposition by loss of acetonitrile prior to combustion. IR (KBr):
2327m (νPH), 2274w (νCN).
(η5-Cyclopentadienyl)(1-vinyl-1,4,7-triphosphacyclononane)-
iron(II) hexafluorophosphate, 4a. A solution of [(η5-Cp)Fe(1,2-
dpe)(CH3CN)]PF6, 1a (1.00 g, 2.49 mmol), and trivinylphosphine (0.28
mL, 2.5 mmol) in 1,2-dichloroethane (50 mL) was heated at 80 °C for
2 h. After cooling, the volatiles were removed in vacuo to give 2a as
a yellow solid. The yellow residue was dissolved in chlorobenzene (100
mL) containing excess triethylamine (0.5 mL) and the resulting solution
heated at 80 °C for 60 h. 31P{1H} NMR spectroscopy showed the
successive formation of 3a and 4a, and the mixture was worked up
(Acetonitrile)(η5-trimethylsilylcyclopentadienyl)(1,2-diphos-
phinoethane)iron(II) tetrafluoroborate, 1b. A solution of [{η5-
(Me3Si)Cp}Fe(CO)2(CH3CN)]BF4 (1.00 g, 2.65 mmol) and 1,2-
diphosphinoethane (0.25 mL, 2.7 mmol) in acetonitrile (100 mL) was
irradiated for 12 h with a Hanovia 125W UV lamp. The solvent was
subsequently removed and the resultant residue crystallized from hot
tetrahydrofuran to give 1b as a red crystalline solid. Yield ) 0.90 g
(82%). 31P{1H} NMR (CDCl3, 36.23 MHz): δ ) 3.0. 1H NMR (CDCl3,
1
300 MHz}: δ ) 5.81 (d br, 2H, PH2, JPH ) 356 Hz), 4.67 (d, 2H,
PH2, 1JPH ) 340 Hz), 4.50 (s br, 2H, Cp), 4.12 (s br, 2H, Cp), 2.23 (s
br, 3H, CH3CN), 2.2-1.8 (m br, 4H, CH2), 0.26 (s, 9H, SiCH3).
Elemental analysis calcd for C12H24NSiP2BF4Fe: C, 34.72; H, 5.84;
N, 3.37. Found: C, 34.3; H, 5.5; N, 2.9. IR (KBr): 2334m (νPH), 2269m
(νCN).
(Acetonitrile){η5-1,3-bis(trimethylsilyl)cyclopentadienyl}(1,2-
diphosphinoethane)iron(II) hexafluorophosphate, 1c. This was
prepared as for 1b using [{η5-(Me3Si)2Cp}Fe(CO)2(CH3CN)]PF6 (1.00
(28) Malische, W.; Gunzelmann, N.; Thirase, K.; Neumayer, M. J. Organomet.
Chem. 1998, 571, 215.
9
3826 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Template Synthesis of 1,4.7-Triphosphacyclononanes
A R T I C L E S
upon complete conversion of 3a to 4a. The mixture was filtered hot,
cooled, and concentrated to small volume. After standing at -20 °C
overnight, the bright orange crystals of 4a were isolated by filtration.
Yield ) 0.42 g (36%). 31P{1H} NMR (CD2Cl2, 36.23 MHz): δ ) 129.0
(t, J ) 22 Hz), 96.0 (d, J ) 22 Hz). 1H NMR (CD2Cl2, 400 MHz): δ
) 6.51 (m, 1H, PCH:CH2), 6.00 (dd, 1H, PCH:CH2), 6.19 (d br, 2H,
362 Hz, PH), 5.73 (t, 1H, PCH:CH2), 4.38 (s, 5H, Cp), 2.2-1.5 (m,
12H, CH2). 13C{1H} NMR (CD2Cl2, DEPT, 100 MHz): δ ) 135.3 (d,
34 Hz, PCH:CH2), 128.6 (d, 3 Hz, PCH:CH2), 78.6 (s, Cp), 29.0 (dt,
30 and 7 Hz, CH2), 24.7 (t, 22 Hz, CH2), 23.9 (m, CH2). IR (KBr):
2334m (νPH). MS (APCI) m/z: 327 (100) [(η5-Cp)Fe(9-aneP3H2C2H3)]+.
Elemental analysis calcd for C13H22F6P4Fe: C, 33.07; H, 4.71. Found:
C, 33.2; H, 4.6.
solid. Yield ) 0.41 g (36%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ )
134.2 (t, 21 Hz), 129.3 (t, 21 Hz), 96.0 (t, 21 Hz). 1H NMR (CDCl3, 300
MHz): δ ) 7.48 (m, 5H, Ph), 6.67 (m, 1H, PCH:CH2), 6.35 (d br, 2H,
357 Hz, PH), 6.07 (dd, 1H, PCH:CH2), 5.87 (t, PCH:CH2), 4.36 (br,
1H, Cp), 4.23 (br, 1H, Cp), 4.12 (br, 1H, Cp), 4.08 (br, 1H, Cp), 2.4-
1.6 (m, 12H, CH2), 0.11 (s, 9H, SiCH3). 13C{1H} NMR (CDCl3, DEPT,
75.6 MHz): δ ) 137.0 (d, 39 Hz, ipso-Ph), 135.2 (d, 36 Hz, PCH:
CH2), 130.7 (s, Ph), 129.6 (d, 8 Hz, Ph), 129.5 (d, 11 Hz, PCH:CH2),
128.0 (s, Ph), 89.7 (s, CH), 89.0 (s, CH), 79.5 (s, CH), 79.0 (CH),
29.0 (obs, 3 × CH2), 27.7 (dd, 28 and 11 Hz, CH2), 23.7 (dd, 31 and
17 Hz, CH2), 0.3 (s, SiCH3). IR (KBr): 2363m (νPH). MS (APCI) m/z:
475 (100) [(η5-Me3SiCp)Fe(9-aneP3HPhC2H3)]+. Elemental analysis
calcd for C22H34SiF6P4Fe: C, 42.58; H, 5.48. Found: C, 42.3; H, 5.9.
(η5-Trimethylsilylcyclopentadienyl)(1-vinyl-1,4,7-triphosphacy-
clononane)iron(II) tetrafluoroborate, 4b. A solution of [(η5-Me3-
SiCp)Fe(1,2-dpe)(CH3CN)]BF4, 1b (1.00 g, 2.41 mmol), and trivi-
nylphosphine (0.28 mL, 2.50 mmol) in 1,2-dichloroethane (50 mL) was
heated at 80 °C for 24 h. After cooling, the mixture was filtered, the
volatiles were removed in vacuo, and the orange-yellow residue was
extracted into ethanol (150 mL) and filtered. The ethanol was removed
in vacuo and the residue chromatographed on neutral alumina (10 × 1
cm) using 0.3% MeOH in dichloromethane as eluent. The fractions
containing 4b were dried (MgSO4) and the solvents removed in vacuo
giving 4b as a yellow solid. Yield ) 0.50 g (43%). 31P{1H} NMR
(CDCl3, 121.7 MHz): δ ) 131.0 (t, J ) 21 Hz), 98.4 (d, J ) 21 Hz)
1H NMR (CDCl3, 300 MHz): δ ) 6.58 (m, 1H, PCH:CH2), 6.22 (d
br, 2H, 354 Hz, PH), 6.04 (dd, 1H, PCH:CH2), 5.80 (t, PCH:CH2),
4.56 (br, 2H, Cp), 4.46 (br, 2H, Cp), 2.3-1.6 (m, 12H, CH2), 0.12 (s,
9H, SiCH3) 13C{1H} NMR (CDCl3, DEPT, 75.6 MHz): δ ) 134.5
(dd, 34 and 2.3 Hz, PCH:CH2), 127.4 (d, 3.5 Hz, PCH:CH2), 88.3 (s,
CH), 78.0 (s, CH), 27.7 (dt, 29 and 6 Hz, CH2), 23.7 (t, 23 Hz, CH2),
23.2 (dd, 29 and 14 Hz, CH2), 0.2 (s, SiCH3) IR (KBr): 2340m (νPH).
MS (APCI) m/z: 399 (100) [(η5-Me3SiCp)Fe(9aneP3-H2C2H3)]+.
Elemental analysis calcd for C16H30BSiF4P3Fe: C, 39.53; H, 6.23.
Found: C, 39.4; H, 6.2.
{η5-1,3-Bis(trimethylsilyl)cyclopentadienyl}(1-vinyl-1,4,7-tri-
phosphacyclononane)iron(II) tetrafluoroborate, 4c. A solution of
[{η5-(Me3Si)2Cp}Fe(1,2-dpe)(CH3CN)]BF4, 1c (1.00 g, 2.05 mmol),
and trivinylphosphine (0.23 mL, 2.05 mmol) in 1,2-dichloroethane (50
mL) was heated at 80 °C for 48 h. After cooling, the mixture was
filtered, and the volatiles were removed in vacuo to give an orange-
brown solid. The solid was exhaustively extracted into toluene (4 ×
100 mL) before concentrating the extracts in vacuo to crystallize 4c as
a bright yellow solid. Yield ) 0.71 g (62%). 31P{1H} NMR (CDCl3,
145.8 MHz): δ ) 126.0 (t, J ) 18 Hz), 98.7 (d, J ) 18 Hz). 1H NMR
(CDCl3, 400 MHz): δ ) 6.54 (m, 1H, PCH:CH2), 6.28 (d br, 2H, 354
Hz, PH), 6.11 (dd, 1H, PCH:CH2), 5.80 (t, PCH:CH2), 4.58 (d, 2H,
Cp), 4.38 (d, 1H, Cp), 2.3-1.7 (m, 12H, CH2), 0.16 (s, 18H, SiCH3)
13C{1H} NMR (CDCl3, DEPT, 100 MHz): δ ) 134.7 (d, 32 Hz, PCH:
CH2), 127.4 (d, 5 Hz, PCH:CH2), 96.1 (s, CH), 86.0 (s, CH), 80.5 (s,
C), 28.5 (dt, 30 and 7 Hz, CH2), 23.4 (t, 23 Hz, CH2), 22.3 (dd, 27 and
14 Hz, CH2), 0.2 (s, SiCH3) IR (KBr): 2383m (νPH). MS (APCI) m/z:
471 (100) [{η5-(Me3Si)2Cp}Fe(9-aneP3H2C2H3]+. Elemental analysis
calcd for C19H38BSi2F4P3Fe: C, 40.87; H, 6.87. Found: C, 40.8; H,
6.8.
{η5-1,3-Bis(trimethylsilyl)cyclopentadienyl}(1-phenyl-4-vinyl-
1,4,7-triphosphacyclononane)iron(II) hexafluorophosphate, 4f. A
solution of [{η5-(Me3Si)2Cp}Fe(Phdpe)(CH3CN)]PF6, 1f (1.02 g, 1.64
mmol), and trivinylphosphine (0.19 mL, 1.69 mmol) in chlorobenzene
(30 mL) containing Et3N (0.2 mL) was heated at 105 °C for 24 h.
After cooling, the mixture was filtered, and the volatiles were removed
in vacuo to give an orange-brown solid. The solid was extracted into
ethanol (2 × 100 mL), filtered, and the volatiles were removed in vacuo.
The yellow solid was purified by passage through a short column (1 ×
7 cm) of neutral alumina using 0.5% methanol in dichloromethane as
eluent. Yield ) 0.401 g (35%). 31P{1H} NMR (CDCl3, 121.7 MHz):
δ ) 129.7 (t, J ) 18 Hz), 125.7 (t, 18 Hz), 100.1 (t, 18 Hz). 1H NMR
(CDCl3, 400 MHz): δ ) 7.47 (m, 5H, Ph), 6.69 (m, 1H, PCH:CH2),
6.41 (d br, 2H, 352 Hz, PH), 6.03 (dd, 1H, PCH:CH2), 5.82 (t, 1H,
PCH:CH2), 4.54 (br, 1H, Cp), 4.24 (br, 1H, Cp), 4.09 (br, 1H, Cp),
2.4-1.7 (m, 12H, CH2), 0.07 (s, 9H, SiCH3), 0.05 (s, 9H, SiCH3).
13C{1H} NMR (CDCl3, DEPT, 75.6 MHz): δ ) 137.4 (d, 36 Hz, ipso-
Ph), 135.5 (d, 31 Hz, PCH:CH2), 130.7 (s, Ph), 130.3 (d, 8 Hz, Ph),
129.3 (d, 7 Hz, PCH:CH2), 128.0 (s, Ph), 98.6 (s, CH), 90.4 (s, CH),
86.0 (s, CH), 81.0 (s, C), 80.0 (s, C), 31.0 (m, CH2), 29.9 (m, CH2),
28.4 (m, CH2), 26.9 (m, CH2), 24.0 (m, CH2), 22.2 (m, CH2), 0.7 (s,
SiCH3), 0.5 (s, SiCH3). IR (KBr): 2347m (νPH). MS (APCI) m/z: 547
(100) [{η5-(Me3Si)2Cp}Fe(9-aneP3HPhC2H3)]+. Elemental analysis
calcd for C25H42Si2F6P4Fe: C, 43.35; H, 6.12. Found: C, 43.4; H, 6.5.
{η5-(+)-Neomenthylcyclopentadienyl}(1-phenyl-4-vinyl-1,4,7-
triphosphacyclononane)iron(II) hexafluorophosphate, 4g. A solution
of [{η5-(+)-neomenthylCp)Fe(Phdpe)(CH3CN)]PF6, 1g (0.32 g, 0.51
mmol), and trivinylphosphine (0.15 mL of a 50% solution in toluene,
0.67 mmol) in chlorobenzene (40 mL) containing triethylamine (0.1
mL) was heated at 120 °C for 72 h. After cooling, the mixture was
filtered, the volatiles were removed in vacuo, and the orange-yellow
residue was extracted into ethanol (2 × 75 mL) and filtered. The ethanol
was removed in vacuo and the residue chromatographed on neutral
alumina (20 × 1 cm) using gradient elution from 0.5% to 5% MeOH
in dichloromethane. The fractions containing 4g were dried (MgSO4)
and the solvents removed in vacuo giving 4g as a yellow solid. Yield
) 0.06 g (17%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 134.6 (t,
18 Hz), 133.9 (t, 18 Hz), 129.9 (t, 18 Hz), 128.6 (t, 18 Hz), 100.1 (t,
1
18 Hz), 99.2 (t, 18 Hz). H NMR (CDCl3, 400 MHz): δ ) 7.46 (m,
5H, Ph), 6.65 (m, 1H, PCH:CH2), 6.23 (d br, 1H, 357 Hz, PH), 6.04
(dd, 0.5H, PCH:CH2), 5.95 (dd, 0.5H, PCH:CH2), 5.80 (t, 0.5H, PCH:
CH2), 5.79 (t, 0.5H, PCH:CH2), 4.36 (br, 0.5H, Cp), 4.16 (br, 0.5H,
Cp), 4.14 (br, 0.5H, Cp), 4.01 (br, 0.5H, Cp), 3.98 (br, 0.5H, Cp), 3.92
(br, 0.5H, Cp), 3.88 (br, 0.5H, Cp), 3.83 (br, 0.5H, Cp), 2.6-0.5 (m,
31H, CH, CH2, CH3). 13C{1H} NMR (CDCl3, DEPT, 75.6 MHz): δ )
137.4 (d, 31 Hz, ipso-Ph), 136.9 (d, 31 Hz, ipso-Ph), 135.5 (d, 33 Hz,
PCH:CH2), 134.9 (d, 31 Hz, PCH:CH2), 130.6 (s, Ph), 129.6 (obs, Ph
and PCH:CH2), 127.7 (s br, Ph), 98.9, (s, CH), 98.6 (s, CH), 86.7 (s,
CH), 85.9 (s, CH), 82.5 (s, CH), 81.4 (s, CH), 81.0.5 (s, CH), 80.9 (s,
CH), 69.4 (s, C), 48.4 (s), 43.1 (d, 14 Hz), 35.4 (s), 34.7 (s), 34.6 (s),
28.5 (obs), 23.5 (s), 23.1 (s), 22.0 (d, 11 Hz), 20.5 (s). IR (KBr): 2363m
(νPH). MS (APCI) m/z: 541 (40) [{η5-(+)-neomenthylCp}Fe(9-aneP3-
{η5-Trimethylsilylcyclopentadienyl}(1-phenyl-4-vinyl-1,4,7-tri-
phosphacyclononane)iron(II) hexafluorophosphate, 4e. A solution
of [(η5-Me3SiCp)Fe(Phdpe)(CH3CN)]PF6, 1e (1.00 g, 1.82 mmol), and
trivinylphosphine (0.21 mL, 1.90 mmol) in chlorobenzene (40 mL)
containing triethylamine (0.2 mL) was heated at 90 °C for 36 h. After
cooling, the mixture was filtered, the volatiles were removed in vacuo
and the orange-yellow residue was extracted into ethanol (2 × 75 mL)
and filtered. The ethanol was removed in vacuo and the residue chroma-
tographed on neutral alumina (10 × 1 cm) using 0.15% MeOH in di-
chloromethane as eluent. The fractions containing 4e were dried
(MgSO4) and the solvents removed in vacuo giving 4e as a yellow
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3827

A R T I C L E S
Edwards et al.
HPhC2H3)]+. Elemental analysis calcd for C29H44F6P4Fe: C, 50.74; H,
6.47. Found: C, 50.5; H, 6.8.
(s, CH), 26.7 (dt, 27 and 6 Hz, CH2), 24.3 (t, 23 Hz, CH2), 23.9 (dd,
26 and 10 Hz, CH2), 9.2 (d, 5 Hz, CH3), 0.2 (s, SiCH3). IR (KBr):
2357m (νPH). MS (APCI) m/z: 399 (100) [(η5-Me3SiCp)Fe(9-aneP3H2-
Et)]+. Elemental analysis calcd for C16H32BSiF4P3Fe: C, 39.37; H, 6.62.
Found: C, 39.5; H, 6.6.
{η5-1,3-Bis(trimethylsilyl)cyclopentadienyl}(1-phenyl-1,4,7-triph-
osphacyclononane)iron(II) hexafluorophosphate, 4h. A solution of
[{η5-(Me3Si)2Cp}Fe(dpe)(CH3CN)]PF6, 1c (1.00 g, 1.97 mmol), divi-
nylphenylphosphine (0.32 mL, 1.97 mmol) and triethylamine (1 mL)
in 1,2-dichloroethane (50 mL) was heated at 80 °C for 60 h. After
cooling, the mixture was filtered, and the volatiles were removed in
vacuo to give a dark brown solid. The solid was extracted into ethanol
(100 mL), filtered, and the solvent removed in vacuo. The residue was
chromatographed on neutral alumina (15 × 1 cm), the yellow complex
being eluted with dichloromethane. The solution was dried (MgSO4)
and the solvent removed in vacuo to give 4h. Yield ) 0.40 g (29%).
31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 129.8 (t, J ) 18 Hz), 97.0
{η5-1,3-Bis(trimethylsilyl)cyclopentadienyl}(1-ethyl-1,4,7-triph-
osphacyclononane)iron(II) hexafluorophosphate, 5c. This was pre-
pared in an analogous fashion to the monosilylcyclopentadienyl
derivative 5b using [{η5-(Me3Si)2Cp)Fe(9-aneP3H2C2H3)]PF6, 4c, as
precursor. Yield ) 0.91 g (91%). 31P{1H} NMR (CD2Cl2, 121.7
MHz): δ ) 136.5 (t, 21 Hz), 97.1 (d, 21 Hz). 1H NMR (CD2Cl2, 400
MHz): δ ) 6.24 (d br, 2H, 357 Hz, PH), 4.56 (s br, 2H, Cp), 4.49 (s
br, 1H, Cp), 2.09 (m, 2H, CH2CH3), 2.2-1.5 (m, 12H, CH2), 1.26 (dt,
3H, 15 and 8 Hz, CH2CH3), 0.17 (s, 18H, SiCH3). 13C{1H} NMR (CD2-
Cl2, DEPT, 100 MHz): δ ) 95.1 (s, CH), 86.3 (s, CH), 81.8 (s, C),
27.5 (dt, 28 and 6 Hz, CH2), 25.7 (d, 22 Hz, CH2), 24.2 (t, 23 Hz,
CH2), 23.7 (dd, 27 and 13 Hz, CH2), 9.6 (d, 6 Hz, CH3), 0.5 (s, SiCH3).
IR (KBr): 2344m (νPH). MS (APCI) m/z: 471 (100) [{η5-(Me3Si)2Cp}-
Fe(9-aneP3H2Et]+. Elemental analysis calcd for C19H40Si2F6P4Fe: C,
36.89; H, 6.53. Found: C, 37.3; H, 6.6.
1
(d, J ) 18 Hz). H NMR (CDCl3, 300 MHz): δ ) 7.5-7.4 (m, Ph),
6.36 (d br, 2H, 360 Hz, PH), 4.43 (s br, 2H, CH), 4.12 (s br, 1H, CH),
2.35-1.70 (m, 12H, CH2), 0.07 (s, 18H, SiCH3). 13C{1H} NMR (CDCl3,
DEPT, 75.6 MHz): δ ) 136.8 (d, 36 Hz, C), 130.7 (s, CH), 130.0 (d,
9 Hz, CH), 129.3 (d, 9 Hz, CH), 95.1 (s, CH), 87.4 (s, CH), 82.3 (s,
C), 30.1 (dt, 29 and 4.5 Hz, CH2), 24.1 (t, 23 Hz, CH2), 23.2 (dd, 29
and 14 Hz, CH2), 0.42 (s, SiCH3). IR (KBr): 2383m (νPH). MS (APCI)
m/z: 521 (100) [{η5-(Me3Si)2Cp}Fe(9-aneP3H2Ph]+. Elemental analysis
calcd for C23H39Si2F6P4Fe: C, 41.50; H, 5.92. Found: C, 41.0; H, 5.6.
(η5-1,2,3,4,5-Pentamethylcyclopentadienyl)(1-phenyl-1,4,7-triph-
osphacyclononane)iron(II) hexafluorophosphate, 4i. A solution of
[(η5-Cp*)Fe(1,2-dpe)(CH3CN)]PF6, 1d (1.00 g, 2.12 mmol), divinylphe-
nylphosphine (0.36 mL, 2.20 mmol) and triethylamine (1 mL) in 1,2-
dichloroethane (50 mL) was heated at 80 °C for 60 h. After cooling,
the mixture was filtered, and the volatiles were removed in vacuo to
give a dark brown solid. The solid was extracted into ethanol (100
mL), filtered, and the solvent was removed in vacuo. The residue was
chromatographed on neutral alumina (15 × 1 cm), the yellow complex
being eluted with dichloromethane. The solution was dried (MgSO4)
and the solvent removed in vacuo to give 4i. Yield ) 0.20 g (16%).
31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 119.7 (t, 4 Hz), 106.0 (d, 4
Hz). 1H NMR (CDCl3, 300 MHz): δ ) 7.42 (m, 3H, Ph), 7.04 (m br,
2H, Ph), 5.50 (d br, 2H, 344 Hz, PH), 2.1-1.1 (m, 12H, CH2), 1.38 (s,
15H, CH3). IR (KBr): 2322m (νPH). MS (APCI) m/z: 447 (100) [(η5-
Me5Cp)Fe(9-aneP3H2Ph)]+. Elemental analysis calcd for C22H34F6P4-
Fe: C, 44.61; H, 5.80. Found: C, 44.4; H, 5.8.
(η5-Trimethylsilylcyclopentadienyl)(1-ethyl-4-phenyl-1,4,7-triph-
osphacyclononane)iron(II) Hexafluorophosphate, 5e. A solution of
[(η5-Me3SiCp)Fe(9-aneP3HPhC2H3)]PF6, 4e (0.40 g, 0.65 mmol), in a
mixture of ethanol (150 mL) and methanol (50 mL) containing 0.02 g
of 10% palladium on carbon was hydrogenated at room temperature
and atmospheric pressure for 10 days. After filtering off the catalyst,
the volatiles were removed in vacuo, and the orange-yellow residue
was recrystallized from ethanol (10 mL) at 4 °C. Yield ) 0.25 g (63%).
31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 139.4 (t, 21 Hz), 134.1 (t,
1
21 Hz), 96.4 (t, 21 Hz). H NMR (CDCl3, 400 MHz): δ ) 7.41 (m,
5H, Ph), 6.23 (d br, 1H, 352 Hz, PH), 4.33 (s br, 1H, Cp), 4.26 (s br,
1H, Cp), 4.00 (s br, 1H, Cp), 3.69 (s br, 1H, Cp), 2.13 (m, 2H, CH2-
CH3), 2.1-1.2 (m br, 12H, CH2), 1.14 (m, CH2CH3), 0.08 (s, 9H,
SiCH3). 13C{1H} NMR (CDCl3, DEPT, 75.6 MHz): δ ) 137.3 (d, 36
Hz, ipso-Ph), 130.5 (s, Ph), 129.8 (d, 8 Hz, Ph), 129.4 (d, 8 Hz, Ph),
89.3 (s, CH), 87.1 (s, CH), 79.7 (s, CH), 78.5 (s, CH), 30.3 (dd, 28
and 14 Hz, CH2), 29.3 (dd, 28 and 14 Hz), 27.6 (m, 2 × CH2), 25.2 (d,
22 Hz, CH2), 24.2 (dd, 31 and 14 Hz, CH2), 23.6 (dd, 31 and 17 Hz,
CH2), 9.7 (d, 5 Hz, CH3), 0.5 (s, SiCH3). IR (KBr): 2357m (νPH). MS
(APCI) m/z: 477 (100) [(η5-Me3SiCp)Fe(9-aneP3HPhEt)]+. Elemental
analysis calcd for C22H36SiF6P4Fe: C, 42.45; H, 5.84. Found: C, 42.1;
H, 6.0.
{η5-1,3-Bis(trimethylsilyl)cyclopentadienyl}(1-ethyl-4-phenyl-
1,4,7-triphosphacyclononane)iron(II) hexafluorophosphate, 5f. A
solution of [{η5-(Me3Si)2Cp}Fe(9-aneP3HPhC2H3)]PF6, 4f (0.60 g, 0.87
mmol), in ethanol (150 mL) containing 0.20 g of 10% palladium on
carbon was hydrogenated at room temperature and atmospheric pressure
for 5 days. After filtering off the catalyst, the volatiles were removed
in vacuo, and the orange-yellow residue was recrystallized from ethanol
at 4 °C. Yield ) 0.45 g (75%). 31P{1H} NMR (CDCl3, 121.7 MHz):
δ ) 136.2 (t, 24 Hz), 129.4 (t, 24 Hz), 99.6 (t, 21 Hz). 1H NMR (CDCl3,
300 MHz): δ ) 7.46 (m, 5H, Ph), 6.43 (d br, 1H, 356 Hz, PH), 4.61
(s br, 1H, Cp), 4.26 (s br, 1H, Cp), 4.13 (s br, 1H, Cp), 2.4-1.6 (m,
14H, CH2), 1.29 (m, CH2CH3), 0.07 (s, 9H, SiCH3), 0.05 (s, 9H, SiCH3).
13C{1H} NMR (CDCl3, DEPT, 75.6 MHz): δ ) 137.7 (d, 33 Hz, ipso-
Ph), 130.7 (s, Ph), 130.2 (d, 8 Hz, Ph), 129.3 (d, 8 Hz, Ph), 97.6 (s,
CH), 89.5 (s, CH), 85.8 (s, CH), 81.0 (s, C), 79.8 (s, C), 31.3 (dd, 28
and 14 Hz, CH2), 27.8 (dd, 28 and 14 Hz), 26.9 (dd, 28 and 14 Hz,
CH2), 26.5 (dd obs, CH2), 25.9 (d, 22 Hz, CH2), 23.6 (dd, 31 and 14
Hz, CH2), 23.1 (dd, 31 and 14 Hz, CH2), 9.7 (d, 5 Hz, CH3), 0.7 (s,
SiCH3), 0.6 (s, SiCH3). IR (KBr): 2348m (νPH). MS (APCI) m/z: 549
(100) [{η5-(Me3Si)2Cp}Fe(9-aneP3HPhEt)]+. Elemental analysis calcd
for C25H44Si2F6P4Fe: C, 43.23; H, 6.40. Found: C, 43.5; H, 6.7.
Preparation of [(η5-Cp)Fe(9-aneP3Et2,C2H3)]BF4 (6a), [(η5-
Me3SiCp)Fe(9-aneP3Et2,C2H3)]BF4 (6b), and [(η5-Cp)Fe(9-aneP3Et2,-
Ph)]PF6 (6k). These complexes were prepared by the same procedure.
(η5-1,2,3,4,5-Pentamethylcyclopentadienyl)(1-benzyl-1,4,7-triph-
osphacyclononane)iron(II) hexafluorophosphate, 4j. A solution of
[(η5-Cp*)Fe(1,2-dpe)(CH3CN)]PF6, 1d (1.00 g, 2.12 mmol), divinyl-
benzylphosphine (0.39 mL, 2.20 mmol), and triethylamine (1 mL) in
1,2-dichloroethane (50 mL) was heated at 80 °C for 60 h. After cooling,
the mixture was worked up as for 4i. Yield ) 0.28 g (22%). 31P{1H}
1
NMR (CDCl3, 121.7 MHz): δ ) 118.9 (t, 4 Hz), 106.3 (d, 4 Hz). H
NMR (CDCl3, 300 MHz): δ ) 7.22 (t, 7.8 Hz, 2H, Ph), 7.17 (t obs,
1H, Ph), 7.04 (d, 8.0 Hz, 2H, Ph), 5.57 (d br, 2H, 344 Hz, PH), 3.29
(d, 10.9 Hz, 2H, CH2), 2.1-1.0 (m, 12H, CH2), 1.77 (s, 15H, CH3). IR
(KBr): 2315m (νPH). MS (APCI) m/z: 461 (100) [(η5-Me5Cp)Fe(9-
aneP3H2Bz)]+. Elemental analysis calcd for C23H36F6P4Fe: C, 45.56;
H, 6.00. Found: C, 45.7; H, 6.1.
(η5-Trimethylsilylcyclopentadienyl)(1-ethyl-1,4,7-triphosphacy-
clononane)iron(II) tetrafluoroborate, 5b. A solution of [(η5-Me3-
SiCp)Fe(9-aneP3H2C2H3)]BF4, 4b (1.00 g, 2.41 mmol), in ethanol (100
mL) containing 0.01 g of 10% palladium on carbon and several drops
of water was hydrogenated at room temperature and atmospheric
pressure for 2 days. After filtering off the catalyst, the volatiles were
removed in vacuo and the orange-yellow residue was crystallized from
ethanol (10 mL) at 4 °C. Yield ) 0.85 g (85%). 31P{1H} NMR ({CD3}2-
1
CO, 121.7 MHz): δ ) 140.2 (t, 21 Hz), 97.5 (d, 21 Hz). H NMR
({CD3}2CO, 300 MHz): δ ) 6.31 (d br, 2H, 356 Hz, PH), 4.78 (s br,
2H, Cp), 4.74 (s br, 2H, Cp), 2.28 (m, 2H, CH2CH3), 2.2-1.6 (m br,
12H, CH2), 1.28 (dt, 15 and 8 Hz, CH2CH3), 0.18 (s, 9H, SiCH3). 13C-
{1H} NMR ({CD3}2CO, DEPT, 75.6 MHz): δ ) 88.1 (s, CH), 78.5
9
3828 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006

Template Synthesis of 1,4.7-Triphosphacyclononanes
A R T I C L E S
To a solution of [(η5-Cp)Fe(9-aneP3H2C2H3)]BF4, 4a, [(η5-Me3SiCp)-
Fe(9-aneP3H2C2H3)]BF4, 4b, or [(η5-Cp)Fe(9-aneP3H2C2H3)]PF6, 4h
(300 mg), in THF (25 mL, 100 mL for 4a) at -78 °C was added
potassium tert-butoxide (2.2 molar equiv), and the mixture was stirred
for 5 min at this temperature before warming to -20° for 15 min. The
mixture was cooled to -78 °C and excess ethyl bromide (0.5 mL) added
thereto. The mixture was stirred at -78 °C for 30 min then at ambient
temperature overnight. After filtering, the solvent was removed in vacuo,
and the orange-yellow solids were partitioned between CH2Cl2 (20
mL) and water (20 mL). The organic phase was separated, dried over
MgSO4, and the solvent removed in vacuo to yield yellow solids that
were recrystallized from ethanol.
6a: Yield ) 0.29 g (87%). 31P{1H} NMR {(CD3)2CO, 121.7
MHz}: δ ) 140.3 (d, 25 Hz), 131.1 (t, 25 Hz) ppm. 1H NMR {(CD3)2-
CO, 400 MHz}: δ ) 6.63 (m, 1H), 5.84 (dd, 1H), 5.67 (t, 1H), 4.20
(q, 5H), 2.07 (m, 4H), 1.56 (m, 12H), 1.02 (m, 6H). MS (APCI) m/z:
383 (100) [(η5-Cp)Fe(9-aneP3Et2C2H3)]+. Elemental analysis calcd for
C17H30BF4P3Fe: C, 43.44; H, 6.45. Found: C, 43.4; H, 6.5.
6b: Yield ) 0.18 g (53%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ
) 139.9 (d, 24 Hz), 128.5 (t, 24 Hz). 1H NMR (CDCl3, 300 MHz): δ
) 6.59 (m, 1H), 6.04 (dd, 1H), 5.80 (t, 1H), 4.42 (s br, 2H), 4.37 (s br,
2H), 2.12 (m, 4H), 1.76 (m, 12H), 1.27 (m, 6H), 0.15 (s, 9H). MS
(APCI) m/z: 455 (100) [(η5-Me3SiCp)Fe(9-aneP3Et2C2H3)]+. Elemental
analysis calcd for C20H38SiP3BF4Fe: C, 44.30; H, 7.08. Found: C, 44.4;
H, 7.1.
°C for 30 min then at room temperature overnight. After filtering, the
solvent was removed in vacuo, and the orange-yellow solids were
partitioned between CH2Cl2 (20 mL) and water (20 mL). The organic
phase was isolated, dried over MgSO4, and the solvent removed to
yield a yellow solid that was purified by passage through a column
(10 × 1.5 cm) of neutral alumina using dichloromethane as eluent.
Yield ) 0.54 g (62%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 139.5
1
(t, 27 Hz), 136.7 (d, 27 Hz). H NMR (CDCl, 300 MHz): δ ) 4.34
(d, 1.3 Hz, 5H), 2.2-1.2 (m, 33H), 0.92 (t, 7.0 Hz, 6H). 13C{1H} NMR
(CDCl3, 75.6 MHz): δ ) 76.4 (s, Cp), 33.5 (s br, CH2), 31.9 (m, CH2),
27.5 (m, CH2), 24.8 (d obs, CH2), 24.7 (s, CH2), 22.3 (s, CH2), 14.0 (s,
CH3), 9.1 (s, CH3). MS (APCI) m/z: 469 (100) [(η5-Cp)Fe{9-aneP3-
Et(C5H11)2}]+. Elemental analysis calcd for C23H44F1.8P3.3Br0.7Fe: C,
48.56; H, 7.81. Found: C, 49.0; H, 8.0.
Preparation of [(η5-Cp)Fe(9-aneP3Et3)]BF4 (7a) and [(η5-Me3SiCp)-
Fe(9-aneP3Et3)]BF4 (7b). These complexes were prepared by the same
procedure. Hydrogen was bubbled through a solution of [(η5-Cp)Fe(9-
aneP3Et2C2H3)]BF4, 6a, or [(η5-Me3SiCp)Fe(9-aneP3Et2C2H3)]BF4, 6b
(300 mg), in ethanol (75 mL) containing 10% palladium on carbon
(20 mg) for 24 h. After filtering, the solvent was removed in vacuo
and the residue crystallized from ethanol.
7a: Yield ) 0.29 g (97%). 31P{1H} NMR {(CD3)2CO, 121.7
MHz}: δ ) 140.1 (s). 1H NMR {(CD3)2CO, 300 MHz}: δ ) 4.55 (q,
5H), 2.30 (m, 6H), 1.86 (m, 12H), 1.26 (m, 9H). 13C{1H} NMR {-
(CD3)2CO, 75.6 MHz}: δ ) 77.4 (s, Cp), 27.6 (dd, 11 and 5 Hz, CH2),
27.4 (dd, 13 and 5 Hz, CH2), 24.9 (dd, 16 and 10 Hz, CH2), 9.2 (s,
CH3). MS (APCI) m/z: 385 (100) [(η5-Cp)Fe(9-aneP3Et3)]+. Elemental
analysis calcd for C17H32BF4P3Fe: C, 43.25; H, 6.85. Found: C, 43.1;
H, 6.8.
7b: Yield ) 0.29 g (96%). 31P{1H} NMR {(CD3)2CO, 121.7
MHz}: δ ) 139.0 (s). 1H NMR {(CD3)2CO, 300 MHz}: δ ) 4.65 (q,
4H), 2.28 (m, 6H), 1.86 (m, 12H), 1.28 (m, 9H), 0.21 (s, 9H). 13C{1H}
NMR {(CD3)2CO, 75.6 MHz}: δ ) 89.8 (s, CH), 75.4 (s, C), 26.5
(m, CH2), 24.8 (dd, 16 and 8 Hz, CH2), 8.6 (d, 5 Hz, CH3), 0.26 (s,
SiCH3). MS (APCI) m/z: 457 (100) [(η5-Me3SiCp)Fe(9-aneP3Et3)]+.
Elemental analysis calcd for C20H40SiP3BF4Fe: C, 44.13; H, 7.42.
Found: C, 44.1; H, 7.5.
6k: Yield ) 0.11 g (96%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ
) 139.6 (d, 25 Hz), 135.4 (t, 25 Hz). 1H NMR (CDCl3, 300 MHz): δ
) 7.46 (m, 5H), 4.12 (s, 5H), 2.21 (m, 4H), 1.77 (m, 12H), 1.27 (m,
6H). 13C{1H} NMR (CDCl3, DEPT, 75.6 MHz): δ ) 137.9 (d, 38 Hz,
C), 130.4 (d, 2 Hz, CH), 129.4 (d, 8 Hz, CH), 129.3 (d, 8 Hz, CH),
77.3 (s, CH), 28.9 (dt, 28 and 6 Hz, CH2), 26.9 (m 2 × CH2), 24.7 (m,
CH2), 9.2 (s, CH3). MS (APCI) m/z: 433 (100) [(η5-Cp)Fe(9-aneP3-
Et2Ph)]+. Elemental analysis calcd for C21H32P4F6Fe: C, 43.62; H, 5.59.
Found: C, 43.2; H, 5.3.
(η5-Cyclopentadienyl)(1-phenyl-4-pentyl-7-ethyl-1,4,7-triphos-
phacyclononane)iron(II) hexafluorophosphate, 7l. To a solution of
[(η5-Me3SiCp)Fe(9-aneP3HPhEt)]PF6, 5e (0.20 g, 0.32 mmol), in THF
(20 mL) at -78 °C was added potassium tert-butoxide (0.20 g, 1.77
mmol), and the mixture was stirred for 5 min at this temperature before
warming to -20° for 15 min. The mixture was cooled to -78 °C and
excess 1-bromopentane (0.1 mL) added thereto. The mixture was stirred
at -78 °C for 30 min then at ambient temperature overnight. After
filtering, the solvent was removed in vacuo, and the orange-yellow
solids were partitioned between CH2Cl2 (20 mL) and water (20 mL).
The organic phase was isolated, dried over MgSO4, and the solvent
removed to yield a yellow solid that was purified by passage through
a column (10 × 1.5 cm) of basic alumina using dichloromethane as
eluent followed by evaporation of solvent in vacuo. Yield ) 0.12 g
(53%). 31P{1H} NMR (CDCl3, 121.7 MHz): δ ) 139.5 (t, 25 Hz),
P,P′,P′′-Trioxo-1,4,7-triethyl-1,4,7-triphosphacyclononane, 8. To
a stirred solution of [(η5-Me3SiCp)Fe(9-aneP3Et3)]BF4, 7b (0.08 g, 0.15
mmol), in dichloromethane (10 mL) in air was added bromine (0.5
mL) whereupon the solution got hot. The dark brown solution was
layered with water (10 mL) and the mixture stirred for 2 days. The
dichloromethane was removed on a rotary evaporator and the dark
aqueous suspension filtered through Celite. After taking the solution
to a pH of approximately 11 with aq. NaOH, the suspension was filtered
to remove iron oxides and the filtrate stirred with Dowex 50 × 8 resin
in the H+ form for 2 h. The resin was removed by filtration and the
aqueous solution taken to dryness. The residue was dried by azeotroping
with EtOH (2 × 10 mL) before being triturated with dry acetone to
give a hygroscopic off-white solid. Yield ) 0.04 g (85%). 31P{1H}
1
136.7 (t, 25 Hz), 135.3 (t, 25 Hz). H NMR (CDCl, 300 MHz): δ )
1
NMR (D2O, 121.7 MHz): δP 65.2. H NMR (D2O, 300 MHz): δH
7.45 (m, 5H), 4.10 (d, 1.3 Hz, 5H), 2.2-1.2 (m, 25H), 0.92 (t, 6.6 Hz,
3H). 13C{1H} NMR (CDCl3, 75.6 MHz): δ ) 137.9 (d, 36 Hz, ipso-
Ph), 130.4 (s, Ph), 129.4 (d, 6 Hz, Ph), 129.3 (d, 6 Hz, Ph), 68.1 (s,
Cp), 34.9 (s, CH2), 33.5 (d, 11 Hz, CH2), 31.7 (d, 22 Hz, CH2), 28.8
(dd, 28 and 14 Hz, CH2), 27.1 (m obs), 25.7 (s, CH2), 24.8 (d, 6 Hz,
CH2), 24.6 (d, 14 Hz, CH2), 22.3 (s, CH2), 19.0 (s, CH2), 14.0 (s, CH3),
9.1 (d, 5 Hz, CH3). MS (APCI) m/z: 475 (100) [(η5-Cp)Fe(9-aneP3-
EtPhC5H11)]+. Elemental analysis calcd for C24H38F6P4Fe: C, 46.46;
H, 6.19. Found: C, 46.7; H, 6.2.
(η5-cyclopentadienyl)(1,4-dipentyl-7-ethyl-1,4,7-triphosphacy-
clononane)iron(II)] bromide/hexafluorophosphate, 7m. To a solution
of the hexafluorophosphate salt of 5b (0.70 g, 1.28 mmol) in THF (40
mL) at -78 °C was added potassium tert-butoxide (0.4 g, 3.54 mmol),
and the mixture was stirred for 5 min at this temperature before warming
to 0 °C for 15 min. The mixture was cooled to -78 °C and excess
1-bromopentane (1 mL) added thereto. The mixture was stirred at -78
2.24 (m, 12H), 1.97 (m, 6H), 1.19 (m, 9H). MS (ES) m/z: 335 (40)
[9-aneP3(O)3Et3 + Na]+. Elemental analysis calcd for C12H27P3O3: C,
46.15; H, 8.73. Found: C, 45.8; H, 8.8. IR (KBr): 1145 cm-1 (υPO).
X-ray Crystallography. All crystallographic measurements were
made on an Enraf Nonius CAD4 diffractometer. The structures were
2
solved via direct methods29 and refined on Fo by full matrix least
squares22 using all unique data corrected for Lorentz and polarization
factors.30 With the exception of C30 and C39 (7b), all non-hydrogen
atoms were anisotropic. The hydrogen atoms were inserted in idealized
positions with Uiso set at 1.2 or 1.5 times the Ueq of the parent atom.
(29) Sheldrick, G. M. SHELX97 [Includes SHELXS97, SHELXL97, CIFTAB]s
Programs for Crystal Structure Analysis (Release 97-2); Tammanstrasse
4, D-3400; Institu¨t fu¨r Anorganische Chemie der Universita¨t: Go¨ttingen,
Germany, 1998.
(30) Harms, K.; Wocadlo, S. XCAD4-CAD4 Data Reduction; University of
Marburg: Marburg, Germany, 1995.
9
J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006 3829

A R T I C L E S
Edwards et al.
The weighting scheme used was w ) 1/[σ2(Fo)2 + (0.0999P)2], where
P ) [max(Fo)2 + 2(Fc)2]/3; this gave satisfactory agreement analyses.
Empirical absorption corrections were carried out by the XABS31 and
DIFABS32 methods.
Crystal data for complex 4c, C38H76B2F8Fe2P6Si4, M ) 1116.49,
monoclinic, space group P21/c, a ) 20.252(4), b ) 8.595(2), c )
31.418(6) Å, â ) 101.56(3)°, V ) 5357.9(19) Å3, Z ) 4, D ) 1.384
g cm-3, µ(Mo KR) ) 0.865 mm-1, F(000) ) 2336, T ) 293(2) K,
yellow blocks, crystal size 0.15 × 0.15 × 0.15 mm; 8058 independent
measured reflections, F2 refinement, R1 ) 0.1047 wR2 ) 0.2262, 5905
independent observed absorption corrected reflections [|Fo| > 2σ(|Fo|),
2θmaz ) 48°], 570 parameters.
clinic, space group P21, a ) 8.226(3), b ) 21.665(5), c ) 15.256(5)
Å, â ) 99.48(8)°, V ) 2681.7(13) Å3, Z ) 4, D ) 1.492 g cm-3
,
µ(Mo KR) ) 0.896 mm-1, F(000) ) 1256, T ) 293(2) K, yellow plates,
crystal size 0.2 × 0.2 × 0.15 mm; 4964 independent measured
reflections, F2 refinement, R1 ) 0.0868 wR2 ) 0.2156, 2820 independent
observed absorption corrected reflections [|Fo| > 2σ(|Fo|), 2θmaz ) 50°],
582 parameters, 133 restraints.
Acknowledgment. The authors wish to thank the EPSRC
(P.D.N.) and the Leverhulme Trust (D.L.) for funding, and Drs.
David E. Hibbs, Mark Thornton-Pett, and Li-ling Ooi for their
assistance with crystallography.
Crystal data for complex 7b, C20H40F6FeP4Si, M ) 602.34, mono-
Supporting Information Available: Crystallographic data
(CIF) are available. This material is available free of charge
via the Internet at http://pubs.acs.org.
(31) XABS2; Parkin, S.; Moezzi, B.; Hope H. J. Appl. Crystallogr. 1995, 28,
53-56.
(32) DIFABS; Walker, N.; Stuart, D. Acta Crystallogr., Sect A 1983, 39, 158-
166.
JA0578956
9
3830 J. AM. CHEM. SOC. VOL. 128, NO. 11, 2006