Structure and properties of the macrocyclic tridentate ferrocenylphosphine ligand (-PhPC5H4-)3

Article abstract of DOI:10.1021/om800057w

Isolation and characterization were carried out for a novel tridentate ferrocenylphosphine macrocycle, (-PhPC₅H₄FeC ₅H₄-)₃, as follows. A photolytic ring-opening reaction of PPh-bridged [1]ferrocenophane in ether gave a mixture of its oligomers. After their sulfurization, GPC separation of low-molecular-weight species afforded two isomers of a macrocyclic trimer, 1,1″:1′,1: 1?,1-tris(phenylthiophos-phinidene)tris(ferrocene), in which three 1,1′-ferrocenediyl units and three P(S)Ph groups were alternately linked to form a macrocyclic ring. Although yields of both isomers were low (17% in total), they were successfully desulfurized in good yields without configurational inversion at their phosphorus centers by treatment with MeOTf/P(NMe₂)₃ (OTf = CF₃SO₃), to give the respective tridentate macrocyclic phosphine ligands. The molecular structure of one isomer (C₃ isomer) with C₃ symmetry was determined by X-ray analysis, while the other was identified as the C _s isomer on the basis of ¹H, ¹³C, and ³¹P NMR data. When the C₃ isomer was heated in toluene at around 80°C, it isomerized gradually but almost completely to the C _s isomer with the activation energy ΔG₃₅₀ ^{double barred pipe} = 26.2 ±0.6 kcal mol^-1. The reaction of AgOTf with the C₃ isomer in CH₂Cl₂ gave a mononuclear silver complex in which the C₃ isomer encircled the Ag⁺ ion as a tridentate ligand. To our surprise, a similar reaction using the C_s isomer gave the same silver complex as above, indicating that a facile conversion of the C_s isomer to the C ₃ isomer took place upon coordination to the Ag⁺ ion at room temperature.

Full text of DOI:10.1021/om800057w

Organometallics 2008, 27, 2457–2463
2457
Structure and Properties of the Macrocyclic Tridentate
Ferrocenylphosphine Ligand (-PhPC5H4FeC5H4-)3
Tsutomu Mizuta,* Tomoyuki Aotani, Yuki Imamura, Kazuyuki Kubo, and
Katsuhiko Miyoshi
Department of Chemistry, Graduate School of Science, Hiroshima UniVersity, Kagamiyama 1-3-1,
Higashi-hiroshima 739-8526, Japan
ReceiVed January 22, 2008
Isolation and characterization were carried out for a novel tridentate ferrocenylphosphine macrocycle,
(-PhPC5H4FeC5H4-)3, as follows. A photolytic ring-opening reaction of PPh-bridged [1]ferrocenophane
in ether gave a mixture of its oligomers. After their sulfurization, GPC separation of low-molecular-
weight species afforded two isomers of a macrocyclic trimer, 1,1′′:1′,1′′′′:1′′′,1′′′′′-tris(phenylthiophos-
phinidene)tris(ferrocene), in which three 1,1′-ferrocenediyl units and three P(S)Ph groups were alternately
linked to form a macrocyclic ring. Although yields of both isomers were low (17% in total), they were
successfully desulfurized in good yields without configurational inversion at their phosphorus centers by
treatment with MeOTf/P(NMe2)3 (OTf ) CF3SO3), to give the respective tridentate macrocyclic phosphine
ligands. The molecular structure of one isomer (C3 isomer) with C3 symmetry was determined by X-ray
1
analysis, while the other was identified as the Cs isomer on the basis of H, 13C, and 31P NMR data.
When the C3 isomer was heated in toluene at around 80 °C, it isomerized gradually but almost completely
q
to the Cs isomer with the activation energy ∆G350 ) 26.2 ( 0.6 kcal mol-1. The reaction of AgOTf
with the C3 isomer in CH2Cl2 gave a mononuclear silver complex in which the C3 isomer encircled the
Ag+ ion as a tridentate ligand. To our surprise, a similar reaction using the Cs isomer gave the same
silver complex as above, indicating that a facile conversion of the Cs isomer to the C3 isomer took place
upon coordination to the Ag+ ion at room temperature.
Ferrocenylphosphines constitute an important subset of
phosphorus ligands serving as a very useful and powerful
auxiliary ligand in metal-complex catalysts for organic reac-
tions.1 For example, bis(diphenylphosphino)ferrocene (dppf) is
widely used as an excellent ligand for homogeneous catalyses,2
and 1,2-disubstituted ferrocenylphosphines have been exten-
sively applied as planar-chirality ligands for asymmetric
catalyses.3–6
preparation of a variety of their derivatives, since they readily
open their ring structure to release a substantial steric strain
built into a distorted [1]ferrocenophane framework, as demon-
strated by some groups.20–28 Our group also carried out a
photoinduced ring-opening oligomerization of 1.29,30 From a
mixture of the oligomers obtained, two types of dimers were
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Phosphorus-bridged [1]ferrocenophanes such as 1 are not only
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distorted ferrocene unit7–19 but also useful precursors for the
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* To whom correspondence should be addressed. Fax: +81-82-424-0729.
E-mail: mizuta@sci.hiroshima-u.ac.jp.
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10.1021/om800057w CCC: $40.75
2008 American Chemical Society
Publication on Web 05/09/2008

2458 Organometallics, Vol. 27, No. 11, 2008
Mizuta et al.
isolated and characterized to be bidentate ferrocenylphosphine
macrocycles 2 bearing syn- and anti-PPh-bridged [1.1]ferro-
cenophane frameworks.30
particular, Edwards et al. recently established a metal-template
hydrophosphination method, in which a ring structure was
constructed on a metal center by a self-coupling reaction among
primary or secondary alkenylphosphines.48 By use of the
ingenious template method above, a dozen P3 macrocycles are
known to date, but those having a functional group on their
chelate rings have not been reported so far.
In our oligomerization reaction of 1 mentioned above, cyclic
oligomers with a ring size larger than that of 2 must have been
formed. Actually, we briefly mentioned the formation of the
trimer 3.29 The P3 macrocycle 3 is unprecedented in that chelate
backbones are composed only of ferrocene units known to
function as a redox-active bulky group. Since such a P3
macrocycle serves potentially as a unique tridentate ligand to a
transition metal, we report herein the characterization and
structural properties of 3 in detail. In addition, 3 is found to
readily undergo pyramidal inversion at the phosphorus center
upon coordination to an Ag+ ion at room temperature, in marked
contrast to our consensus that usual trialkyl- and triarylphos-
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°C.49,50 The mechanism for the unexpectedly facile inversion
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Tridentate Ferrocenylphosphine Macrocycle
Organometallics, Vol. 27, No. 11, 2008 2459
described earlier.51 After the insoluble anti dimer, sparingly
soluble syn dimer, and polymeric precipitates were removed
by filtration, the remaining oligomeric mixture was sulfurized
with elemental sulfur. Subsequent separation was performed
with a preparative-scale recycling-GPC equipment. MALDI-
TOF mass spectra of each band revealed that the only last three
bands contained low-molecular-weight oligomers of interest to
us: a mixture of trimeric and tetrameric sulfides in band 1,
another trimeric sulfide in band 2, and a small amount of a
dimeric syn sulfide in band 3, which were eluted in this order.
Band 2, containing the trimeric sulfide 4b only, was completely
separated from the other two bands after 6 recycles, while the
other trimeric sulfide in band 1, 4a, was found at this stage to
be still contaminated with the tetrameric sulfide. Complete
separation of 4a was marginally achieved after overnight (25
times) recycles. Trace amounts of higher oligomers up to a
hexamer were detected in some bands eluted earlier.
Figure 1. Molecular structure of 4a with thermal ellipsoids given
at the 50% probability level. Three independent molecules were
found in the asymmetric unit, but only one of the three similar
structures is shown. Selected bond distances (Å) and angles (deg):
P1-S1 ) 1.9586(7), P2-S2 ) 1.9585(8), P3-S3 ) 1.9582(7),
P1-C1 ) 1.796(2), P1-C26 ) 1.7915(19), P2-C6 ) 1.790(2),
P2-C11 ) 1.797(2), P3-C16 ) 1.793(2), P3-C21 ) 1.793(2);
C1-P1-C26)109.80(9),C6-P2-C11)109.66(9),C16-P3-C21
) 109.72(9).
A
31P{1H} NMR spectrum of 4a showed a sharp singlet at
39.2 ppm, implying that 4a has a C3-symmetric cyclic structure.
The structure of 4a was determined by X-ray analysis, as shown
in Figure 1, where three ferrocene units and three P(S)Ph groups
are alternately linked to form a macrocyclic framework. The
molecule has C3 symmetry with the PdS and P-Ph bonds on
each phosphorus atom directed outside the ring. On the other
hand, the other trimeric sulfide isolated from band 2, 4b, gave
a complicated 31P{1H} NMR spectrum consisting of five peaks:
a broad peak at 42.7 ppm and a sharp peak at 44.3 ppm with a
2:1 intensity ratio and three minor signals with equal intensity
at 40.4, 40.5, and 40.7 ppm. The complexity is probably due to
the presence of conformational isomers. In fact, when 4b was
heated above 50 °C, considerable peak broadening was observed
for the three minor signals, while the first two signals became
sharper, suggesting that the frequency of the conformational
interconversion became comparable to or greater than the NMR
time scale. In accordance with the complicated 31P{1H} NMR
spectrum, 1H and 13C{1H} NMR signals of 4b were too
complicated to assign. Final structural assignment of 4b was
accomplished after it was desulfurized (vide infra).
Figure 2. Molecular structure of 3a with thermal ellipsoids given
at the 50% probability level. Selected bond distances (Å) and angles
(deg): P1-C1 ) 1.818(5), P1-C26 ) 1.829(6), P2-C6 ) 1.825(6),
P2-C11 ) 1.824(6), P3-C16 ) 1.822(5), P3-C21 ) 1.832(5);
C1-P1-C26 ) 103.4(3), C6-P2-C11 ) 99.5(2), C16-P3-C21
) 102.0(2).
The macrocyclic trimeric sulfides 4a,b were both successfully
desulfurized by treatment with MeOTf (OTf ) CF3SO3) and
P(NMe2)3 with their symmetries retained (eq 1).30,52 The
desulfurized product 3a obtained from 4a showed a single
1
31P{1H} NMR peak at -35.5 ppm. In H and 13C{1H} NMR
three phenyl groups are all located outward to avoid steric
congestion. As a result, the three lone pairs of 3a are all directed
toward the center of the macrocycle, and so 3a is expected to
encircle a metal ion as a tridentate ligand (vide infra). When
3a is compared in structure with the sulfurized derivative 4a
shown in Figure 1, some notable conformational differences
are found. The three PdS bonds in 4a, corresponding to the
three lone pairs in 3a, are directed outside the ring to avoid a
steric repulsion that would emerge if the three PdS bonds were
all directed toward the center of the macrocycle, like the three
lone pairs in 3a. This leads to the three ferrocene units becoming
closer in 4a than in 3a. As a result, 4a is subjected to a limited
conformational flexibility, and therefore, 4a has a 13C{1H} NMR
spectrum in which the 10 carbon atoms in one ferrocene unit
spectra, only four ferrocene proton signals and five C5H4 carbon
signals were observed. These NMR data were consistent with
3a having C3 symmetry, which was unequivocally confirmed
by the crystal structure, shown in Figure 2. The ligand 3a
provides the second example in which the molecular structure
of the free P3 macrocycle has been determined by X-ray
analysis.53 Figure 2 shows that three bulky ferrocene units and
(51) The reaction in THF gave higher polymers as major products.28,29
Mixed solvent systems, for example, THF-ether mixtures, were also
examined but resulted in rather lower yields of the trimer 3.
(52) Omelanczuk, J.; Mikolajczyk, M. Tetrahedron Lett. 1984, 25, 2493–
2496.
(53) Coles, S. J.; Edwards, P. G.; Fleming, J. S.; Hursthouse, M. B.
Chem. Commun. 1996, 293–294.

2460 Organometallics, Vol. 27, No. 11, 2008
Mizuta et al.
Chart 1
are all observed as inequivalent, while 3a, having a more flexible
macrocyclic framework, has only five 13C signals for the
ferrocene units.
Figure 3. Molecular structure of [Ag(3a)]OTf (5) with thermal
ellipsoids given at the 50% probability level. Selected bond
distances (Å) and angles (deg): Ag-P1 ) 2.4600(17), Ag-P2 )
2.4586(17), Ag-P3 ) 2.4663(17), P1-C1 ) 1.827(6), P1-C26
) 1.803(7), P2-C6 ) 1.809(7), P2-C11 ) 1.808(7), P3-C16 )
1.808(7), P3-C21 ) 1.808(7); P1-Ag-P2 ) 110.73(6), P2-Ag-P3
) 110.95(6), P1-Ag-P3 ) 111.30(6), C1-P1-C26 ) 103.5(3),
C6-P2-C11 ) 103.6(3), C16-P3-C21 ) 104.0(3).
(1)
whether the OTf- ion remains in the coordination sphere of
the Ag+ ion in solution.
A similar reaction of the Cs isomer 3b with AgOTf in CH2Cl2
was also carried out at room temperature. To our surprise, the
product had the same 31P{1H} signal as that of 5, indicating
that the Cs isomer 3b has been converted to the C3 isomer 3a
upon coordination to the Ag+ ion. This conversion requires
pyramidal inversion at the phosphorus center which differs in
configuration from the remaining two phosphorus centers (see
Chart 1). In general, pyramidal inversion of tertiary phosphines
requires heating over 100 °C, owing to their high energy barriers
After similar desulfurization of the other isomer, 4b, a
31P{1H} NMR spectrum of the resulting product, 3b, showed
only two sharp signals at -21.7 and -22.8 ppm with a 1:2
intensity ratio, implying that 3b adopts Cs symmetry and is gifted
with a considerable conformational flexibility like 3a. In
principle, only two configurational isomers are possible for a
P3 macrocycle, as shown in Chart 1. Since 3a has been
unambiguously identified as the C3 isomer by X-ray analysis,
3b must be the other isomer having Cs symmetry with one of
the three phosphorus centers inverted in configuration. The Cs
structure of 3b was also deduced by an 1H-1H COSY spectrum,
which was consistent with the presence of three inequivalent
C5H4 rings.
ranging from 30 to 38 kcal mol-1 49,50
Actually, the free ligands
.
3a,b started to interconvert only on heating, and 3a isomerized
gradually but almost completely to the thermodynamically more
stable 3b. When this isomerization process was monitored with
q
31P NMR, the activation barrier was estimated to be ∆G350
)
Reaction with Ag+ Ion. The C3 isomer 3a was allowed to
react with AgOTf in CH2Cl2 to give the expected tricoordinate
silver complex [Ag(3a)]OTf (5), which showed one set of
26.2 ( 0.6 kcal mol-1. Since the macrocycle frameworks of
3a,b are both considered to be sufficiently flexible, like the
related macrocycles (-CH2C5H4FeC5H4-)n (n ) 2, 3),56–59 it
is the inversion barrier of the phosphorus center itself that is
31P{1H} NMR signals centered at -17.3 ppm coupled with
109
107Ag (1J
) 325 Hz) and Ag (1J
31P-107Ag
31P-109Ag
) 375 Hz)
mainly responsible for the present barrier of ca. 26 kcal mol-1
;
1
and only four H and five 13C{1H} NMR signals due to the
three equivalent ferrocene units. The X-ray crystal structure of
5 is shown in Figure 3, where the three phosphorus donors
encircle the Ag+ center with Ag-P bond distances of 2.4600(17),
2.4586(17), and 2.4663(17) Å. They are comparable to those
found in, for example, tricoordinate [Ag(PPh3)3]BF4 and
[Ag2(µ-dppf)(dppf)2](PF6)2.54,55 In addition to the three phos-
phorus donors, an OTf- anion in 5 coordinates weakly to the
[Ag(3a)]+ cation at a much greater Ag-O distance of 2.772(7)
Å, in comparison to the three Ag-P distances. The geometry
around the Ag+ center is thus pseudotetrahedral if the OTf-
anion is included, with three neighboring P-Ag-P angles of
110.73(6), 110.95(6), and 111.30(6)°. It is not known at present
the flexible but bulky ferrocene backbones seem to make no
practical steric contribution to the isomerization barrier. Al-
though the barrier is slightly lower than those expected for
triarylphosphines,49 in part because of the entropic term RT ln
3, it is still sufficiently high to prevent the room-temperature
isomerization; no inversion was in fact observed for 3a,b at
room temperature.
The observed facile inversion induced by the Ag+ ion is
rationally understood, assuming the reaction intermediate shown
(56) Katz, T. J.; Acton, N.; Martin, G. J. Am. Chem. Soc. 1969, 91,
2804–2805.
(57) Lippard, S. J.; Martin, G. G. J. Am. Chem. Soc. 1970, 92, 7291–
7296.
¨
(58) Karlsson, A.; Lo¨ewendahl, M.; Hilmersson, G.; Davidsson, O.;
(54) Camalli, M.; Caruso, F. Inorg. Chim. Acta 1987, 127, 209.
(55) Neo, S.-P.; Hor, T. S. A.; Zhou, Z.-Y.; Mak, T. C. W. J. Organomet.
Chem. 1994, 464, 113.
Ahlberg, P. J. Phys. Org. Chem. 1996, 9, 436–438.
(59) Rudzinski, J. M.; Osawa, E. J. Phys. Org. Chem. 1993, 6, 107–
112.

Tridentate Ferrocenylphosphine Macrocycle
Organometallics, Vol. 27, No. 11, 2008 2461
solvents were dried and distilled from sodium (for hexane), sodium/
benzophenone (for ether and THF), or P2O5 (for CH2Cl2). These
purified solvents were stored under an N2 atmosphere. The PPh-
bridged [1]ferrocenophane 1 was prepared according to a previously
described method.25c Other reagents were used as received.
NMR spectra were recorded on JEOL LA-300 and LA-500
spectrometers. 1H and 13C NMR chemical shifts were reported
relative to Me4Si and were determined by reference to the residual
solvent peaks. 31P NMR chemical shifts were reported relative to
H3PO4 (85%) used as an external reference. Elemental analyses
were performed with a Perkin-Elmer 2400CHN elemental analyzer.
MALDI-TOF mass spectra were recorded on a Shimadzu/Kratos
Axima CFR+ mass spectrometer.
Figure 4. Mechanism for the pyramidal inversion of the third
phosphorus center induced by the backside attack of an Ag+ ion.
Each cylindrical shape represents a ferrocene unit.
in Figure 4. First, the Ag+ ion is considered to be bound to 3b
in a manner shown at the left side of Figure 4, where the two
phosphorus centers donating their lone pairs are those bearing
the same configuration in the free Cs isomer shown in Chart 1.
The Ag+ ion then attacks the third phosphorus center. It is
generally accepted that a phosphorus center in the transition
state of the pyramidal inversion adopts a trigonal-planar
geometry in which the lone pair resides in the p orbital. If a
metal ion interacts with this lone pair, considerable stabilization
of the planar phosphorus center will be attained, resulting in a
reduction in the inversion barrier. In the center structure of
Figure 4, the two phosphorus centers of 3b bind to the Ag+ ion
as a bidentate chelate so as to locate the Ag+ ion at a position
suitable for interaction with the lone pair on the third phosphorus
center. Finally, the inversion is accomplished to form [Ag(3a)]+,
in which the starting 3b has been converted to 3a and the Ag+
ion has attained a full interaction with the third phosphorus atom.
Fryzuk et al. also reported a similar reduction in the inversion
barrier for the reaction of a P2N2 macrocycle with MCl3 (M )
Al, Ga), in which the pyramidal inversion at 80 °C was
accelerated by 20-70 times compared with that of the free
ligand.60 It is interesting to note that, when the solvent for the
present reaction of 3b with AgOTf was changed from CH2Cl2
to THF, the 31P{1H} NMR spectrum of the resulting silver
complex showed complicated coupling patterns at -9.1 and
-18.0 ppm with a 2:1 intensity ratio. These signals could be
analyzed as an A2MX spin system in which only two of the
three phosphorus centers were firmly bound to the 107Ag+ or
109Ag+ ion. The results suggest that 3b coordinates to the Ag+
ion with its Cs configuration retained upon the reaction in THF,
which is in marked contrast to the facile Cs-to-C3 isomerization
observed for the reaction in CH2Cl2. When it is taken into
consideration that the donating ability of THF is stronger than
that of CH2Cl2, coordination of THF to the Ag+ ion probably
interrupts the subsequent interaction of the third phosphorus
center with the Ag+ ion shown in Figure 4.
Photolysis was carried out with Pyrex-glass-filtered emission
from a 400 W mercury arc lamp (Riko-Kagaku Sangyo UVL-400P).
The emission lines used (in nm) and their relative intensities (given
in parentheses) were as follows: 577.0 (69), 546.1 (82), 435.8 (69),
404.7 (42), 365.0 (100), 334.1 (7), 312.6 (38), and 302.2 (9).
Preparative-scale GPC was performed with a recycling HPLC
system (Japan Analytical Industry Model LC-908) with JAIGEL-
1H (20 mm i.d. × 600 mm; exclusion limit 1.0 × 103) and JAIGEL-
2H (20 mm i.d. × 600 mm; exclusion limit 5.0 × 103) columns.
Isolation of Trimeric Sulfides. The PPh-bridged [1]ferro-
cenophane 1 (2040 mg, 6.98 mmol) was dissolved in ether (230
mL). Half portions of the solution were separately put into two
Pyrex Schlenk tubes and irradiated with a 400 W mercury arc lamp
at 0 °C for 2.5 h. Each supernatant solution was collected by
decantation, and the residue in each tube was extracted with ether
(50 mL). All solutions were combined, and ether was removed in
vacuo. The residue was redissolved in CH2Cl2 and allowed to react
with an excess amount of sulfur for 3 h, and this mixture was then
loaded on an Al2O3 column and eluted with THF. An orange band
was collected, and the solvent was removed. The residue dissolved
in CHCl3 was separated with recycling GPC equipment. Only the
last three bands were found to contain low-molecular-weight
oligomers: a mixture of trimeric and tetrameric sulfides in band 1,
another trimeric sulfide in band 2, and a small amount of a syn
dimeric sulfide in band 3, which were eluted in that order. Band 3
and the bands containing oligomers with higher molecular weights
were removed after two times of recycling, and the remaining bands
1 and 2 were further recycled four times to lead to complete
separation. Each band was collected separately, and band 1 was
loaded again. After overnight recycling (25 times), 4a was separated
from the tetramer. After workup, the amounts of 4a,b obtained were
121 mg (5.3%) and 274 mg (12.1%), respectively, both of which
were recrystallized from CH2Cl2. 4a: 1H NMR (300.5 MHz, CDCl3)
δ 3.97 (br, 3H, C5H4), 4.39 (br, 3H, C5H4), 4.7 (br, 3H, C5H4),
4.85 (br, 6H, C5H4), 5.35 (br, 3H, C5H4), 5.53 (br, 3H, C5H4), 5.74
In conclusion, both of the possible C3 and Cs isomers were
isolated for the P3 macrocycle bearing ferrocene units as chelate
backbones. Not only the C3 but also the Cs isomers are found
to coordinate smoothly to the Ag+ ion in CH2Cl2 at room
temperature to give the identical C3-isomer complex. Since the
free C3 isomer can be converted almost completely to the free
Cs isomer upon heating, the direction of the isomerization can
be intentionally controlled by choosing either the heat- or silver-
assisted reaction. The facile Cs-to-C3 isomerization phenomenon
observed in this study affords a new method for the configu-
rational regulation of medium-sized phospha macrocycles.
(br, 3H, C5H4), 7.49 (m, 9H, Ph), 7.86 (dd, JPH ) 13.7 Hz, JHH
)
6.9 Hz, 6H, Ph); 13C{1H} NMR (75.6 MHz, CDCl3) δ 71.4 (d, JPC
) 14 Hz, C5H4), 72.6 (d, JPC ) 13 Hz, C5H4), 72.6 (d, JPC ) 9 Hz,
C5H4), 73.0 (d, JPC ) 9 Hz, C5H4), 73.5 (d, JPC ) 7 Hz, C5H4),
73.7 (d, JPC ) 13 Hz, C5H4), 74.9 (d, JPC ) 9 Hz, C5H4), 76.9 (d,
JPC ) 9 Hz, C5H4), 77.9 (d, JPC ) 100 Hz, C5H4), 82.3 (d, JPC
)
96 Hz, C5H4), 128.2 (d, JPC ) 12 Hz, Ph), 130.9 (d, JPC ) 11 Hz,
Ph), 131.6 (d, JPC ) 2 Hz, Ph), 133.3 (d, JPC ) 89 Hz, Ph); 31P{1H}
NMR (121.7 MHz, CDCl3) δ 39.2 (s). Anal. Calcd for C48H39Fe3P3S3 · 1/3
CH2Cl2: C, 58.01; H, 4.00. Found: C, 58.07; H, 3.78. 4b: 1H NMR
(499.2 MHz, CDCl3) δ 3.90-6.00 (br, 24H, C5H4, major peaks
4.14, 4.50, 4.55, 4.62, 4.89, 5.14, 5.23, 5.90), 7.37 (br, 9H, Ph),
7.69 (br, 2H, Ph), 7.78 (br, 4H, Ph); 13C{1H} NMR (125.5 MHz,
CDCl3) δ 72.7 (br, C5H4), 73.3 (br, C5H4), 73.8 (br, C5H4), 74.3
(br, C5H4), 76.5 (br, C5H4), 78.1 (br, C5H4), 80.9 (br d, JPC ) 98
Hz, C5H4), 82.5 (br d, JPC ) 98 Hz, C5H4), 83.3 (br d, JPC ) 98
Hz, C5H4), 127.9 (d, JPC ) 11 Hz, Ph), 127.9 (d, JPC ) 11 Hz, Ph),
130.9 (br, Ph), 131.1 (d, JPC ) 11 Hz, Ph), 131.3 (d, JPC ) 10 Hz,
Ph), 136.0 (d, JPC ) 93 Hz, Ph); 31P{1H} NMR (202.1 MHz,
Experimental Section
General Remarks. All reactions were carried out under an
atmosphere of dry nitrogen using Schlenk tube techniques. All
(60) Fryzuk, M. D.; Giesbrecht, G. R.; Rittig, S. J. Inorg. Chem. 1998,
37, 6928–6934.

2462 Organometallics, Vol. 27, No. 11, 2008
Mizuta et al.
Table 1. Crystallographic Data
4a
3a
5
formula
cryst color, habit
cryst syst
space group
a/Å
b/Å
c/Å
C48H39Fe3P3 · CHCl3
orange, plate
triclinic
C48H39Fe3P3S3 · 2C4H8O
orange, stick
C49H39AgF3Fe3O3P3S · C6H4Cl2
orange, plate
monoclinic
P21/n (No. 14)
13.3090(2)
24.3990(4)
16.3170(3)
90.0
106.752(1)
90.0
5073.69(15)
4
trigonal
j
j
P1 (No. 2)
R3 (No. 148)
12.6200(4)
13.0130(5)
14.9790(6)
94.816(2)
95.710(2)
118.712(1)
2122.14(1)
2
49.6210(2)
49.6210
25.4250(1)
90.0
90.0
120.0
54 215.4(3)
42
R/deg
ꢀ/deg
γ/deg
V/Å3
Z
temp/K
200
1.350
200
1.088
200
1.518
µ(Mo KR)/mm-1
diffractometer
MacScience DIP2030 imaging plate
no. of rflns
measd
9073
6405
0.064
0.150
28 659
26 606
0.042
11 030
8014
0.070
obsd (I > 2.00σ(I), 2θ < 55°)
R1 (I > 2σ(I))
wR2a
0.114
0.181
GOF
1.089
0.0527/11.86
1.053
0.0589/166.15
1.071
0.0505/58.46
a/ba
2
2 2
2
2
a wR2 ) {∑[w(Fo - Fc ) ]/∑[w(Fo2)2]}1/2; w ) 1/[σ2(Fo2) + (ap)2 + bp]; p ) (Fo + 2Fc )/3.
CDCl3) δ 40.4 (s), 40.5 (s), 40.7 (s), 42.7 (br), 44.3 (s). Anal. Calcd
for C48H39Fe3P3S3 · 2/3CH2Cl2: C, 56.80; H, 3.95. Found: C, 56.77;
H, 3.85.
Desulfurization of 4a. To 4a (100 mg, 0.10 mmol) dissolved
NMR (202.1 MHz, CDCl3): δ -17.3 (d-d, 1
J
Ag ) 325 Hz, 1
31P-107
31P-109Ag
J
) 375 Hz). Anal. Calcd for C49H39AgF3Fe3O3P3S: C,
51.93; H, 3.47. Found: C, 51.67; H, 3.34.
Isomerization of the C3 Trimer to the Cs Trimer. A toluene
solution of the C3 isomer 3a was put into five 5 mm NMR tubes
under an atmosphere of nitrogen. The tubes were transferred to an
NMR probe maintained at 70, 75, 80, 85, and 90 °C, respectively,
and resonances at -36.7 ppm for the isomer 3a and those at -22.8
and -24.0 ppm for the Cs isomer 3b were monitored periodically
by 31P NMR. The isomerization reactions followed reversible first-
order kinetics approaching equilibrium and showed good fits to the
usual plot of -ln{1 - [Cs]/[Cs]eq} vs time. The equilibrium constant
at each temperature was obtained when no further change in each
spectrum was observed.
X-ray Crystallography. Slow diffusion of hexane into solu-
tions of 3a/CHCl3, 4a/THF, and 5/C6H4Cl2 gave crystals suitable
for an X-ray diffraction study. They were mounted separately
on glass fibers. All measurements were made on a Mac Science
DIP2030 imaging plate area detector at 200 K. The data were
collected to a maximum 2θ value of 55.8°. Cell parameters and
intensities for the reflection were estimated using the program
packages of HKL.61 The structures were solved by direct
methods and expanded using Fourier techniques. Non-hydrogen
atoms were refined anisotropically. Hydrogen atoms were located
at ideal positions. All calculations were performed using the
SHELXL-97 crystallographic software package.62 In the crystals
of 3a and 4a, considerably disordered solvent molecules were
refined as molecules having rigid ideal structures. Three
molecules of 4a were found to be independent in the crystal,
one of which lay on a crystallographic 3-fold axis. Details of
data collection and refinement are given in Table 1, and bond
distances and angles, atomic coordinates, and anisotropic thermal
parameters are given as Supporting Information.
in CH2Cl2 (10 mL) was added MeOTf (40 µL, 0.35 mmol). The
mixture was stirred for 3 h at room temperature. The volatiles were
removed in vacuo, and P(NMe2)3 (65 µL, 0.36 mmol) was then
added to the residue dissolved in CH2Cl2 (10 mL) at room
temperature. After the solution was left for 3 h at room temperature,
the volatiles were removed in vacuo. The residue was extracted
with benzene (10 mL), and the solvent was removed. The product
was recrystallized from CH2Cl2 (1 mL)/ether (3 mL) and dried in
1
vacuo to give 3a (70 mg, 78%). H NMR (499.2 MHz, C6D6): δ
4.02 (dt, JPH ) 1.3 Hz, JHH ) 2.4 Hz, 6H, C5H4), 4.05 (br, 6H,
C5H4), 4.24 (dt, JPH ) 1.3 Hz, JHH ) 2.4 Hz, 6H, C5H4), 4.95 (m,
6H, C5H4), 7.17 (m, 9H, Ph), 7.92 (m, 6H, Ph). 13C{1H} NMR
(125.5 MHz, C6D6): δ 69.9 (s, C5H4), 70.1 (s, C5H4), 73.0 (m, C5H4),
82.1 (m, C5H4), 74.1 (m, C5H4), 82.1 (m, C5H4), 128.9 (s, Ph),
135.4 (m, Ph), 140.5 (m, Ph). 31P{1H} NMR (202.1 MHz, C6D6):
δ -35.5 (s). The elemental analysis of 3a did not give satisfactory
and reproducible results, but that of the Ag+ complex with 3a did,
as given below.
Desulfurization of 4b. The desulfurization was carried out
similarly to that for 4a using 4b (100 mg, 0.10 mmol), MeOTf (40
µL, 0.35 mmol), and P(NMe2)3 (65 µL, 0.36 mmol). The residue
was dissolved in CH2Cl2, loaded on an Al2O3 column, and eluted
with CH2Cl2. The first orange band was collected and dried in vacuo
1
to give 3b (85 mg, 94%). H NMR (499.2 MHz, CDCl3): δ 4.08
(br, 6H, C5H4), 4.32 (br, 6H, C5H4), 4.49 (br, 6H, C5H4), 4.62 (br,
6H, C5H4), 7.42 (m, 9H, Ph), 7.74 (m, 6H, Ph). 13C{1H} NMR
(125.5 MHz, CDCl3): δ 71.0 (m, C5H4), 71.2 (m, C5H4), 73.1 (m,
C5H4), 74.2 (m, C5H4), 78.9 (m, C5H4), 128.8 (m, Ph), 130.7 (s,
Ph), 134.8 (m, Ph). 31P{1H} NMR (202.1 MHz, CDCl3): δ -21.7
(s, 1P), -22.8 (s, 2P). Anal. Calcd for C48H39Fe3P3: C, 65.79; H,
4.49. Found: C, 66.14; H, 4.71.
[Ag(3a)]OTf (5). AgOTf (35 mg, 0.14 mmol) was added to 3a
or 3b (120 mg, 0.14 mmol) dissolved in CH2Cl2 (28 mL). After 30
min, the solvent was removed in vacuo. The residue was washed
with ether and hexane and dried to give a yellow powder (136 mg,
88%). 1H NMR (499.2 MHz, CDCl3): δ 4.08 (br, 6H, C5H4), 4.32
(br, 6H, C5H4), 4.49 (br, 6H, C5H4), 4.62 (br, 6H, C5H4), 7.42 (m,
9H, Ph), 7.74 (m, 6H, Ph). 13C{1H} NMR (125.5 MHz, CDCl3): δ
71.0 (m, C5H4), 71.2 (m, C5H4), 73.1 (m, C5H4), 74.2 (m, C5H4),
78.9 (m, C5H4), 128.8 (m, Ph), 130.7 (s, Ph), 134.8 (m, Ph). 31P{1H}
Acknowledgment. This work was supported by Grants-
in-Aid for Scientific Research (Nos. 19350032, 19550066,
(61) Otwinowski, Z.; Minor, W. In Processing of X-ray Diffraction Data
Collected in Oscillation Mode; Carter, C. W., Jr., Sweet, R. M., Eds.;
Academic Press: New York, 1997; Vol. 276 (Macromolecular Crystal-
lography, Part A), pp 307-326.
(62) Scheldrick, G. M. SHELX-97: Programs for Crystal Structure
Analysis; University of Go¨ttingen, Go¨ttingen, Germany, 1997.

Tridentate Ferrocenylphosphine Macrocycle
Organometallics, Vol. 27, No. 11, 2008 2463
Supporting Information Available: Figures giving kinetic data
for the isomerization reaction from 3a to 3b and CIF files giving
full crystallographic data for 3a, 4a, and 5. This material is available
free of charge via the Internet at http://pubs.acs.org.
and 19550067) and in part by a grant on Priority Areas (No.
19027041, Synergy of Elements) from the Ministry of
Education, Culture, Sports, Science, and Technology of
Japan. We thank the Natural Science Center for Basic
Research and Development (N-BARD), Hiroshima Univer-
sity, for the measurement of NMR and mass spectra.
OM800057W