Site selectivity of [RuCp]+ complexation in cyclopenta[ def ]triphenylenes

Article abstract of DOI:10.1021/om5008852

A series of new cyclopenta-fused triphenylenes has been synthesized in high yield and reacted with [Ru(μ₃-Cl)Cp]₄ to form [RuCp(η⁶-arene)]PF₆ complexes. Systematic variation of the cyclopenta[def]triphenylene al

Full text of DOI:10.1021/om5008852

Article
pubs.acs.org/Organometallics
Site Selectivity of [RuCp*]+ Complexation in
Cyclopenta[def]triphenylenes
Bryce R. Hoggard, Christopher B. Larsen, and Nigel T. Lucas*
MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Otago, Dunedin 9016,
New Zealand
S
* Supporting Information
ABSTRACT: A series of new cyclopenta-fused triphenylenes
has been synthesized in high yield and reacted with [Ru(μ3-
Cl)Cp*]4 to form [RuCp*(η6-arene)]PF6 complexes. System-
atic variation of the cyclopenta[def ]triphenylene allowed the
site of complexation to be probed and the influence of the
electronic and steric properties of the substituents in directing
complexation to be assessed. As determined by NMR
spectroscopy and X-ray crystallography, in all cases the
[RuCp*]+ fragment complexes at a peripheral arene ring, rather than at the central arene ring or as a neutral η5-
cyclopentadienyl metallocene adduct. It was shown that electronic influences are minimal, while steric effects afford selective
complexations. The electronic properties of the ligands and complexes were probed with electrochemistry, along with electronic
absorption and emission spectroscopies.
simple arene systems. Larger polycyclic aromatic hydrocarbon
(PAH) ligands that complex [RuCp*]+ have all been
unsubstituted.13,14 To the best of our knowledge, no reports
to date describe the site selectivity of [RuCp*]+ for PAHs with
a range of substitution patterns and types. Furthermore, the
presence of a peripheral cyclopenta-ring, capable of complex-
ation upon deprotonation, allows the preference for benzenoid
versus cyclopentadienyl donor site to be explored. This study
introduces four new substituted cyclopentatriphenylene-based
ligands (1−4) that contain multiple η6-binding sites along with
a single (potential) η5-binding site. Unsubstituted cyclopenta-
[def ]triphenylene (1) is a substructure of sumanene, which
itself has a carbon framework found in buckminsterfullerene,
C60. Sumanene has a curved π-surface15 and therefore offers a
concave and convex surface for η6-binding of metals. Amaya et
al. formed a [RuCp(η6-sumanene)]PF6 complex that was used
to probe the facial selectivity of the [RuCp]+ moiety.16 The
planar parent PAH triphenylene offers only two potential
coordination sites; one of the three equivalent outer rings has
been shown to bind [RuCp*]+.13 The cyclopentatriphenylenes
1−4 synthesized herein offer a planar surface to investigate the
relative effects of electron-donating and sterically bulky
substituents on the preferred coordination site of the
[RuCp*]+ moiety.
INTRODUCTION
■
Cyclopentadienyl (Cp, η5-C5H5) and pentamethylcyclopenta-
dienyl (Cp*, η5-C5Me5) ruthenium complexes with arene
ligands have been extensively studied, forming η6-sandwich
complexes of the type [RuCp(η6-arene)]+ and [RuCp*(η6-
arene)]+ that are generally stable under atmospheric con-
ditions.1−7 The [RuCp*]+ fragment is known to strongly
interact with aromatic hydrocarbons with a high tolerance to
functional groups.3 The resulting ruthenium sandwich com-
plexes have been studied for their interesting electrochemical
and spectroscopic properties, as well as their catalytic activity.8,9
The most popular synthetic route toward simple [RuCp*(η6-
arene)]+ complexes involves the formation of a [RuCp*-
(CH3CN)3]+ complex, which is reacted with the appropriate
arene ligand with heating or UV irradiation.2,5,10 These
methods are generally useful and robust; however, the need
for toxic or expensive Sn and Ag reagents leaves room for
improvement. In 2007 Fairchild et al.5 proposed a slightly
altered route to these target [RuCp*(η6-arene)]+ complexes
that involves the direct reaction of [Ru(μ3-Cl)Cp*]4, a
precursor in previous pathways, with the arene and the aid of
microwave irradiation. The water-soluble chloride salt of the
resultant complex was obtained after short reaction times in
high yields, and the reaction was shown to be reliable for a wide
range of arene ligands. However, the arene ligands studied were
mostly single ring benzene derivatives, naphthalene and
quinoline being the exceptions, with the [RuCp*]+ forced to
bind to the only arene ring present.
RESULTS AND DISCUSSION
■
Synthesis. 4H-Cyclopenta[def ]triphenylene (1) is prepared
in eight high-yielding steps, with an overall isolated yield of
64% starting from the commercially available precursor 9H-
Site selectivity for complexation of [RuCp*]+ to substituted
polyaromatic systems has been little studied. Previous
work1,6,11,12 gives some precious insight into the affinity of
the [RuCp*]+ fragment for a range of mostly monosubstituted
Received: August 29, 2014
© XXXX American Chemical Society
A
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a
Scheme 1. Synthesis of 1, 2, and 3 from 9H-Fluorene with Numbering and Ring Labeling
a
t
Reaction conditions: (i) BuCl, FeCl3, CS2, rt, 3 h; (ii) Br2, I2, CH2Cl2, 0 °C, 1 h; (iii) 3,4-dimethoxyphenylboronic acid, PdCl2(dppf), K2CO3,
toluene, H2O, EtOH, 80 °C, 18 h; (iv) FeCl3, CH3NO2, CH2Cl2, rt, 15 min; (v) BBr3, CH2Cl2, rt, 3 h; (vi) Tf2O, pyridine, CH2Cl2, 0 °C−rt, 40 min;
(vii) Et3SiH, Pd(OAc)2, dppp, DMF, 60 °C, 18 h; (viii) AlCl3, toluene, 60 °C, 3 h.
fluorene (Scheme 1). The compounds 2,6-di(tert-butyl)-9,10-
dimethoxy-4H-cyclopenta[def ]triphenylene (2) and 2,6-di(tert-
butyl)-4H-cyclopenta[def ]triphenylene (3) were formed as
intermediates during the reaction sequence, and 10,11-
dimethoxy-4H-cyclopenta[def ]triphenylene (4) was synthe-
sized in two high-yielding steps from 2,7-di-tert-butyl-4(3,4-
dimethoxyphenyl)-9H-fluorene (5) (Scheme 2). Previously
A series of new [RuCp*(η6-arene)]PF6 complexes have been
synthesized using a minor variation to the method described by
Fairchild and Holman5 (Scheme 3). The reaction of cyclo-
pentatriphenylenes 1−4 with [Ru(μ3-Cl)Cp*]4 (11), as a
source of [RuCp*]+, was performed in 50:50 THF/water, a
larger proportion of THF than was used previously due to
diminished water solubility of the cyclopentatriphenylene
ligands when compared to single arene systems.5 The reaction
mixture in all cases was a dark brown-red color before heating
and was nearly colorless after microwave irradiation. Moderate
yields of the resultant complexes were isolated; however, some
cyclopentatriphenylene starting material was also recovered in
all cases. Increasing the reaction time did not increase the yield
of the target complex, suggesting that 11 may slowly degrade to
a colorless compound during heating or the complexes are not
completely stable during the aqueous workup. The resulting
complexes were isolated as light brown-white solids after
workup, in which the Cl− counterion was exchanged for the
unreported compounds were fully characterized via 1H and 13
C
NMR spectroscopy (Supporting Information, Figure S1), IR
spectroscopy, mass spectrometry, elemental analysis, and X-ray
crystallography for the cyclopentatriphenylene ligands 1−4
(Figures S3−S6).
Scheme 2. Synthesis of 4 from 5
−
more organic-soluble PF6 . The product complexes were stored
away from light (and water) but appeared to be quite stable,
even while heating in organic solvents. Purification by
chromatography or recrystallization from acetone/ether or
CH2Cl2/ether afforded pure material that was characterized by
1H, 13C, and 31P NMR, IR spectroscopy, mass spectrometry,
elemental analysis, and, in most cases, X-ray crystallography.
1
The coordination site for all complexes was identified by H
Reaction conditions: (i) AlCl3, toluene, rt, 2 h; (ii) FeCl3, CH3NO2,
CH2Cl2, rt, 15 min.
NMR spectroscopy, where the aromatic proton signals
B
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ring; however, it is worth noting that the chemical shift for this
signal is ca. 0.6 ppm upfield compared with the related η6-
benzene complex.3 This shift is presumably due to the shielding
caused by the ring-current of adjacent rings A and B. Diffusion
of diethyl ether vapor into a solution of [RuCp*(η6-2)]PF6
yielded single crystals suitable for X-ray diffraction; an ORTEP
diagram of the cation structure is shown in Figure 2.
Scheme 3. Complexation of the Cyclopentatriphenylene
Ligands with [RuCp*]+
Figure 1. Comparison of the symmetrical and unsymmetrical
complexation products of 1 with Ru representing the [RuCp*]+
fragment.
In the absence of the methoxy substituents, as in 3, the bulky
tert-butyl groups provide enough steric hindrance to direct the
complexation of [RuCp*]+ to ring C, analogous to [RuCp*(η6-
2)]PF6. The 1H NMR spectrum of [RuCp*(η6-3)]PF6 contains
only four aromatic signals, indicating that a symmetrical
complex had been formed, with the two signals for ring C
protons seen upfield when compared to the free ligand (7.50
and 6.41 ppm compared to 8.68 and 7.69 ppm).
Interestingly, if only the methoxy groups are present (ligand
4), the complexation is seen exclusively at ring A/B.
Coordination at ring A/B results in an unsymmetrical complex
with two enantiomers that exhibit planar chirality (but with
1
identical H NMR spectra). The site of complexation suggests
corresponding to the coordinated aryl ring were shifted upfield
compared to the rest of the aromatic signals and the free ligand.
Coordination to ring A/B reduces the symmetry of the
triphenylene core, causing double the number of signals to be
present when compared to the free ligand. In no case was there
any sign of η5-complexation to form a bis(cyclopentadienyl)-
type sandwich complex nor η6-complexation to the “empty”
center ring D. Complexation at ring D would be unexpected, as
the Clar model for PAHs17 predicts rings A, B, and C to have
stable discrete sextets of π-electrons, while complexation at ring
D would disturb the aromatic stabilization of all three π-sextets.
X-ray crystallography for most complexes was used to confirm
the coordination site.
that the unfavorable steric effect due to the two methoxy
substituents outweighs any gains due to the electron-donating
effect of these substituents. The 1H NMR spectrum of
[RuCp*(η6-4)]PF6 is more complex than the two previous
examples and a total of eight aromatic signals were identified,
with three (7.25, 6.67, and 6.15 ppm) being upfield of the rest.
These three signals are assigned as protons 1, 2, and 3 of ring A,
where the [RuCp*]+ moiety is bound. The close proximity of
the [RuCp*]+ center to the 4-methylene bridge causes the
upward and downward facing methylene protons to be in
significantly different chemical environments, each diastereo-
topic proton appearing as a doublet with a geminal coupling of
21.5 Hz. The 2D NOESY spectrum displays a cross-peak
between one of the 4-methylene-bridge protons (4.16 ppm)
and the Cp* methyl protons (1.35 ppm) (Figure S2). This
NOESY signal was not observed for the previously described
complexes (where the [RuCp*]+ is further away) and allows
the methylene bridge protons of [RuCp*(η6-4)]PF6 to be
assigned with confidence. The HR-ESI mass spectrum of the
crude product indicated the presence of a small amount of
[RuCp*OH(η6-4)]PF6, a side product due to oxidation of a Cp*
methyl group; the hydroxylated product was separated from
[RuCp*(η6-4)]PF6 using preparative chromatography. The
formation of such a side product is analogous to the
The coordination site for 2 was predicted to be ring C due to
the electron-donating effect of the methoxy substituents
combined with the blocking effect of the tert-butyl groups on
1
rings A and B. The H NMR spectrum for [RuCp*(η6-2)]PF6
contains three aromatic signals, all singlets, suggesting that the
compound maintains the symmetry of the ligand upon
complexation, and therefore the [RuCp*]+ sits on the mirror
plane that perpendicularly bisects the cyclopentatriphenylene
core (Figure 1). One of the aromatic signals is seen particularly
upfield from the rest (7.46 ppm compared to 8.04 and 8.42
ppm in CD3C(O)CD3), typical of arene protons coordinated to
a [RuCp*]+ moiety,18,19 and were assigned as the ring C
protons. The appearance of a large singlet (1.34 ppm)
confirmed the presence of the methyl protons from the Cp*
[RuCp*OH + impurity seen by Fairchild and Holman5 and
]
the [RuCp*OMe]+ impurity seen by Schmid and Lindel, for
which a mechanism explaining its formation is proposed.20 The
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Figure 3. ORTEP of a crystal structure of [RuCp*OH(η6-4)]PF6·
CH3C(O)CH3 showing 50% displacement ellipsoids; PF6− counterion
and solvent omitted for clarity.
and ring C, thereby giving a mixture of isomers. The only
difference between the two isomers formed from complexation
to ring A/B and ring C is where the 4-methylene bridge is
located relative to the metal (Figure 1). Accordingly, the two
isomers behave similarly in chromatography and could not be
separated, so characterization was carried out on the mixture.
Coordination to ring A/B results in an unsymmetrical complex
(as a racemate), while coordination of ring C results in a
symmetrical (achiral) complex (Figure 1).
The overall ratio of the unsymmetrical to symmetrical
isomers by 1H NMR integration was found to be 1:0.6,
1
respectively. With the aid of 2D COSY, NOESY, H−13C
1
1
HSQC, and H−13C HMBC NMR spectroscopic data the H
and 13C NMR signals associated with each isomer were
1
elucidated. The most upfield aromatic H NMR signals were
assigned to [RuCp*]+-coordinated rings, and the diastereotopic
methylene protons of the unsymmetrical isomer were easily
distinguished by a NOESY cross-peak with the Cp* ring methyl
protons.
X-ray Crystallography. Single crystals suitable for X-ray
crystallography were grown for all four cyclopentatriphenylene
ligands, and solid-state structures were determined (Figures
S3−S6 show ORTEP and packing diagrams). For each
cyclopentatriphenylene 1−4, the carbon framework is close
to planar, the methylene bridge insufficient to induce curvature
as is seen for sumanene,22 but nevertheless distorting the
arrangement of the aromatic rings of the triphenylene moiety.
Similar to triphenylene,23 the crystal structure of 1 shows an
offset face-to-face arrangement in “infinite” stacks for each of
the two molecules in the asymmetric unit, with distances of
3.39 and 3.68 Å between aromatic cores. Cyclopentatripheny-
lene 2 forms a similar offset columnar stack, with a separation
of 3.48 Å between aromatic cores, except in this case each
molecule alternates its orientation so that the 4-methylene
protons form bifurcated hydrogen bonds with the methoxy
group oxygens of the neighboring molecules (Figure S4). In
contrast, 3 and 4 both form discrete inversion-related offset
dimers, with interplanar distances of 3.35 and 3.39 Å,
respectively (Figures S5 and S6). Analogous to that in 2, the
packing of cyclopentatriphenylene 4 also utilizes bifurcated
hydrogen bonds to strengthen the supramolecular assembly.
Figure 2. ORTEP diagrams of a crystal structure of [RuCp*(η6-
2)]PF6·(CH2Cl2)2 (top) and [RuCp*(η6-4)]PF6 (middle) shown with
50% displacement ellipsoids, and [RuCp*(η6-1)]PF6·(CH3C(O)-
CH3)0.5 (bottom) shown with 30% displacement ellipsoids for the
major disordered component; PF6 counterions and solvents omitted
for clarity.
−
complex [RuCp*OH(η6-4)]PF6 was fully characterized, and an
ORTEP diagram of the crystal structure is shown in Figure 3.
The 1H NMR spectrum of [RuCp*(η6-1)]PF6 is quite
convoluted compared to the compounds above and previously
reported [RuCpR(η6-triphenylene)]+ complexes.13,21 Fifteen
aromatic signals are present, ranging from 8.76 to 6.19 ppm,
suggesting that monocomplexation has occurred at ring A/B
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Single crystals of the complexes were grown by vapor
diffusion of ether into a concentrated solution of the complex in
acetone or CH2Cl2, yielding colorless crystals in all cases.
ORTEP diagrams of the [RuCp*]+ complexes of 1, 2, and 4
(Figure 2) and a hydroxylated byproduct formed during the
reaction with 4 (Figure 3) are shown. Coordination of the
[RuCp*]+ moiety causes structural changes in the cyclo-
pentatriphenylene ligand, most notably in the elongation of the
complexed aryl ring bonds of the arene ligand. The free
cyclopentatriphenylene ligands 2 and 4 have average bond
lengths of 1.404(6) [ring C] and 1.397(2) Å [ring A], which
lengthen to 1.430(7) and 1.420(3) Å after complexation; this
elongation upon metal binding is common in other [RuCp*-
(η6-arene)]+ sytems.24−26 The C6(centroid)−Ru−C5(centroid)
angles for [RuCp*(η6-2)]PF6 and [RuCp*(η6-4)]PF6 are
179.10° and 179.02°, respectively, indicating that the Cp* sits
close to coplanar with the aryl ring directly above it.
The crystal structure of [RuCp*(η6-1)]PF6·(CH3C(O)-
CH3)0.5 initially refined as the unsymmetrical isomer resulting
from complexation to ring A/B, but residual electron density
suggested a disordered structure with a partial occupancy
methylene bridge opposite the ruthenium. It appears that the
symmetrical complex (complexation at ring C) had cocrystal-
lized at the same site as the major isomeric product and was
refined accordingly with extensive use of restraints. The two
1
components refined to 70:30, in agreement with the H NMR
integrations (although there is no requirement for the solid-
state composition to match that of the bulk sample in solution).
This observation indicates that the intermolecular interactions
in the solid state for the two isomers are very similar, not
surprising due to their very similar shape, differing only in the
position of the methylene bridge (see Figure 1).
Figure 3 shows an ORTEP diagram of a crystal structure for
[RuCp*OH(η6-4)]PF6·CH3C(O)CH3. The Cp* ring bears one
methyl alcohol group formed by the oxidation of a methyl
group during the reaction and for which the hydroxyl is H-
bonded to the acetone oxygen (Figure S7). All the bond
lengths and angles are comparable to [RuCp*(η6-4)]PF6;
however, the dihedral angle between the planes defined by the
arene and cyclopentadienyl ring is only 1.6° compared to 5.8°
in the analogous benzene compound [RuCp*OH(η6-benzene)]+
reported by Fairchild and Holman.27
Figure 4. Molecular packing of [RuCp*(η6-2)]PF6·(CH2Cl2)2 (top)
and [RuCp*(η6-4)]PF6 (bottom) showing C−H···O distances (Å,
blue) and some C−H···F close contacts (2.36−2.64 Å, orange);
solvent molecules omitted for clarity.
The supramolecular structure of all the complexes exhibit
dimers with the cyclopentatriphenylene cores π-stacking and
the [RuCp*]+ coordinated to the outside faces (Figure 4). The
4-methylene protons of [RuCp*(η6-2)]PF6 form bifurcated
hydrogen bonds to the methoxy oxygens in a neighboring
compound. The C−H···O bond lengths of 2.86 and 2.93 Å
(C−H 0.99 Å) indicate weak intermolecular bonding.28 The
dimers formed by [RuCp*(η6-4)]PF6 are more offset in nature
than [RuCp*(η6-2)]PF6 (with C−H···O distances of 4.36 and
3.78 Å), presumably because the tert-butyl groups are not
present to lock the dimers into place.
Electrochemistry. Cyclopentatriphenylenes 1−4 and the
corresponding [RuCp*(η6-arene)]PF6 complexes were inves-
tigated by cyclic voltammetry (acetone/nBu4NPF6, referenced
against internal decamethylferrocene and converted to SCE).
Of the four cyclopentatriphenylene ligands, only the two
methoxy-substituted compounds (2 and 4) showed observable
oxidations (Figure 5) in the working potential window, due to
the electron-donating nature of the substituents increasing the
HOMO energy. Cyclopentatriphenylene 2 was shifted to a
slightly less positive value when compared to 4 (E1/2 = 1.28 V
compared to 1.34 V) due to the extra electron-donating ability
of the tert-butyl substituents. No ligand showed any observable
reductions in the range −2.1 to 1.5 V.
The complexes, however, display only nonreversible
reductions, analogous to the behavior reported for [RuCp*-
(arene)]+ derivatives and other 4d and 5d cationic 18-electron
sandwich complexes and consistent with the reactivity of the
resultant 19-electron neutral complex.13,21,29−35 The complexes
are all reduced at Epc = −1.82 V, except [RuCp*(η6-1)]PF6,
which is reduced at −1.76 V. This anodic shift is thought to be
due to the absence of the electron-donating tert-butyl and
methoxy substituents, although the irreversibility of these
process prevents a detailed analysis. [RuCp*(η6-2)]PF6 and
[RuCp*(η6-3)]PF6 also display daughter peaks (reoxidations)
that were probed using variable scan rates (50−2000 mV/s),
becoming more pronounced as the scan rate increased,
implying the daughter species is short-lived (Figures S8 and
S9). It must be noted that when comparing the reduction
potentials of the complexes, the coordination site is not
consistent across all complexes and the CV data may not give
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Figure 6. Absorption spectra of the ligands (top) and complexes
(bottom), measured in CH2Cl2.
Figure 5. Cyclic voltammograms for 2 and 4 (top) and the complexes
(bottom), measured in acetone with a scan rate of 100 mV/s.
an accurate representation of the effect of ligand substitution on
redox behavior. The related [RuCp*(η6-triphenylene)]PF6
shows a one-electron irreversible reduction (Epc = −1.87 V,
propylene carbonate),13 comparable to the behavior seen for
[RuCp*(η6-1)]PF6.
Electronic Absorption/Emission. The absorption spec-
trum for cyclopentatriphenylene 1 (Figure 6) has a λmax of 260
nm, which is slightly red-shifted when compared to
triphenylene.36 This is consistent with the electron-donating
nature of the 4-methylene bridge decreasing the HOMO−
LUMO gap and is supported by the further red-shift when the
electron-donating methoxy and tert-butyl groups are intro-
duced. The complexes, however, show no discernible trend,
with [RuCp*(η6-4)]PF6 having λmax at a much higher
wavelength, compared to the other three complexes. The
coordination site could also have a role to play, with
[RuCp*(η6-4)]PF6 having full substitution on the ring C,
while the other complexes either have full or some coordination
to ring A/B. The ligands all show a similar higher energy
shoulder peak, and the complexes show a similar lower energy
shoulder peak, indicating the vibronic nature of the transitions.
The complexes also display a weak low-energy band/tail at
∼350 nm, characteristic of MLCT transitions.37
Figure 7. Emission spectra (351 nm excitation) of the ligands,
measured in CH2Cl2.
characteristic of excimer formation.38,39 An unusual low-energy
emission (700−800 nm) is also observed across all ligands and
is believed to originate from an uncharacterized second-order
effect. In contrast, the complexes are nonemissive over the
range 370−867 nm; this behavior is well known for group 8
sandwich complexes.40−43
CONCLUSION
■
A high-yielding route to 4H-cyclopenta[def ]triphenylene 1 via
substituted intermediates 2 and 3 has been described, providing
access to potential ligands with a polycyclic core structure
falling between the known triphenylene and sumanene PAHs.
The complexation site of ligands 1, 2, 3, and 4 with the
The emission spectra (Figure 7) also show a red-shift in
moving from 1 (373 nm) to the most electron-rich ligand (2,
382 nm), analogous to the trend seen in the absorption
spectrum. A broad low-energy shoulder can be observed and is
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the saturated calomel electrode (SCE).46 Absorption spectra were
recorded as DCM solutions on a PerkinElmer Lambda 950 UV−vis−
NIR spectrometer. Emission spectra were recorded as 1 × 10−4 mol
L−1 solutions, using a previously described instrument setup.47
4-Bromo-2,7-di(tert-butyl)-9H-fluorene (7). Fluorene 6 (3.00 g,
10.77 mmol) and I2 (0.150 g, 0.59 mmol) were dissolved in DCM (21
mL) at 0 °C. A solution of Br2 (0.6 mL, 11.65 mmol) in DCM (9 mL)
was added dropwise, and the mixture stirred for 1 h at 0 °C. The
product was extracted into Et2O, washed with water and NaOH
solution, then dried over MgSO4. The solvent was removed in vacuo to
afford 7 as a white solid (3.86 g, quant.). 1H NMR (400 MHz,
CDCl3):44 δ 8.45 (d, J = 8.0 Hz, 1H, H-5), 7.56 (s, 1H, Ar), 7.51 (s,
1H, Ar), 7.48 (s, 1H, Ar), 7.45 (dd, J = 8.0, 2.0 Hz, 1H, H-6), 3.90 (s,
[RuCp*]+ moiety was probed to elucidate the significance of
both the electronic and steric properties of the substituents on
each ligand. It was found that tert-butyl and even methoxy
substituents provided enough steric hindrance to block
coordination to aryl sites bearing these substituents when a
less-hindered site was available. The low sensitivity of the
[RuCp*]+ fragment to arene electronics and the importance of
steric interactions agree with the conclusions of Nolan et al.
resulting from a systematic thermochemical study.1 In the
absence of any substituents, the complexation of [RuCp*]+ was
found to occur at both ring A/B and ring C, with the product
distribution approximately following a statistical distribution. In
no case did complexation occur on the “empty” ring D,
attributed to an expected unfavorable perturbation of the π-
sextet aromaticity of the other three benzenoid rings.
Furthermore, the peripheral five-membered ring did not behave
as a cyclopentadienyl analogue under the conditions of the
complexation studies reported here. Reaction under basic
conditions should facilitate the formation of η5-complexes as
analogues of the catalytically important fluorenyl metallocenes.
The redox and electronic absorption/emission behavior of both
the cyclopenta[def ]triphenylene ligands and their [RuCp*]+
complexes was examined, with the results broadly in line with
those reported for related smaller, unsubstituted PAHs.13 While
the ligands are blue emissive, introduction of a [RuCp*]+
fragment quenches this emission.
t
t
2H, H-9), 1.38 (s, 9H, Bu), 1.36 (s, 9H, Bu).
2,7-Di-tert-butyl-4-(3,4-dimethoxyphenyl)-9H-fluorene (5). A mix-
ture of 7 (2.50 g, 7.00 mmol), 3,4-dimethoxyphenylboronic acid (1.91
g, 10.5 mmol), K2CO3 (3.20 g, 23.1 mmol), toluene (40 mL), water
(20 mL), and ethanol (10 mL) was deoxygenated. PdCl2(dppf) (0.236
g, 0.29 mmol) was added, and the solution heated to 80 °C with
stirring under argon for 18 h. The organic layer was extracted into
DCM, washed with water, and dried over MgSO4. The solvent was
removed in vacuo, followed by purification via column chromatography
1
(SiO2, 20% DCM/PE), to afford 5 as a white solid (2.59 g, 90%). H
NMR (500 MHz, CDCl3): δ 7.56 (d, J = 1.0 Hz, 1H, H-1), 7.53 (d, J =
1.0 Hz, 1H, H-8) 7.22 (d, J = 2.0 Hz, 1H, H-3), 7.11 (dd, J = 8.5, 1.5
Hz, 1H, H-6), 7.04−6.99 (m, 3H, H-2′,5′,6′), 6.94 (d, J = 8.0 Hz, 1H,
H-5), 5.31 (s, 0.3H, CH2Cl2), 3.99 (s, 3H, OCH3), 3.92 (s, 2H, H-9),
3.88 (s, 3H, OCH3), 1.40 (s, 9H, tBu-2), 1.32 (s, 9H, tBu-7). 13C NMR
(126 MHz, CDCl3): δ 149.3, 149.2, 148.8, 148.4, 144.1, 143.8, 139.1
(C-4a), 136.6, 136.5 (C-4b), 134.8, 125.9 (C-3), 123.5 (C-6), 122.1
(C-5), 121.8 (C-8), 121.4 (C-6′), 120.9 (C-1), 112.8 (C-2′/C-5′),
111.2 (C-2′/C-5′), 56.1 (2 × OCH3), 37.3 (C-9), 34.9 (tBu-2, quat),
EXPERIMENTAL SECTION
■
General Experimental Procedures. Inert atmospheres were
achieved under standard Schlenk techniques; if no conditions are
stated, then the reaction was carried out open to the atmosphere.
Microwave reactions were carried out in a sealed glass tube in a CEM
Discover S Class microwave reactor at a fixed temperature by
modulation of power (max 300 W). 2,7-Di(tert-butyl)-9H-fluorene
(6)44 and [Ru(μ3-Cl)Cp*]4 (11)3 were synthesized according to
literature procedures or a variation thereof. All other chemicals were
commercially purchased and used as received. Dry solvents were
obtained from a Pure-Solv MD-6 solvent purification system; all other
solvents were AR grade unless otherwise stated. Spectroscopic and
electrochemical measurements used Aldrich spectroscopic or HPLC
grade solvent. 1H NMR (500 MHz) and 13C NMR (126 MHz) spectra
were recorded on a Varian 500 AR spectrometer at 25 °C and are
referenced to residual nonperdeuterated solvent: CDCl3 (7.26 ppm)
or CD3C(O)CD3 (2.05 ppm) and CDCl3 (77.16 ppm) or CD3C-
(O)CD3 (29.84 ppm), respectively, as reported by Gottlieb et al.45 1H
and 13C NMR spectra were assigned using 2D spectroscopies (COSY,
̃
34.8 (tBu-7, quat), 31.8 (tBu-2, CH3), 31.7 (tBu-7, CH3). IR: ν (cm−1)
2952(s), 1509(s), 1459(s), 1241(s), 1217(s), 1172(s), 1136(s),
1031(s), 833(s), 808(s). Anal. Calcd for C29H34O2·0.1(CH2Cl2): C,
82.61; H, 8.15. Found: C, 82.31; H, 8.60. HR-ESI-MS: m/z 437.243
(100), 438.246 (32), 439.245 (5); calcd for [M + Na]+ (C29H34O2Na)
437.245 (100), 438.248 (32), 439.252 (5).
2,6-Di(tert-butyl)-9,10-dimethoxy-4H-cyclopenta[def ]-
triphenylene (2). A solution of 5 (1.05 g, 2.54 mmol) in HPLC grade
DCM (170 mL) was purged with N2 for 10 min and with the N2
gently bubbling, FeCl3 (1.65 g, 10.2 mmol) in nitromethane (10 mL)
was added dropwise over 5 min. The dark solution was stirred and
bubbled for a further 10 min, upon which the reaction was quenched
with water (60 mL). The organic layer was washed with water until the
aqueous layer was colorless and dried over MgSO4, and the solvent
removed in vacuo. The crude product was purified using column
chromatography (50% DCM/PE), yielding 2 (0.985 g, 94%) as a
white solid. 1H NMR (500 MHz, CDCl3): δ 8.19 (s, 2H, H-1,7), 8.03
(s, 2H, H-8,11), 7.78 (d, J = 1.0 Hz, 2H, H-3,5), 4.28 (s, 2H, H-4),
1
1
NOESY, H,13C-HSQC, and H,13C-HMBC). ESI mass spectra were
recorded on a Bruker MicrOTOF-Q mass spectrometer using a
CH2Cl2 or acetone solution diluted into methanol. MALDI-TOF mass
spectra were recorded on an Applied Biosystems 4800 Tandem TOF
t
4.18 (s, 6H, OCH3), 1.55 (s, 18H, Bu). 13C NMR (126 MHz,
CDCl3): δ 150.7, 149.0, 141.7, 134.9, 125.6, 125.3, 119.9 (C-5, 3),
114.9 (C-1, 7), 105.7 (C-8, 11), 56.3 (OCH3), 37.8 (C-4), 36.0 (tBu,
mass spectrometer with external calibration to within m/z
0.08;
̃
quat), 32.4 (tBu, CH3). IR: ν (cm−1) 2948(s), 2895(m), 1541(s),
solid analyte and TCNQ matrix were mixed using a mini mixer-mill,
suspended in hexane and transferred to the sample plate. Micro-
analyses were performed at the Campbell Microanalytical Laboratory,
University of Otago. IR spectra were recorded neat on a Bruker Alpha-
P FTIR spectrometer with an attenuated total reflectance (ATR)
module over the range 400−4000 cm−1. The electrochemical cell for
cyclic voltammetry was made up of a 1 mm diameter platinum rod
working electrode embedded in a KeL-F cylinder with a platinum
auxiliary electrode and a Ag/AgCl reference electrode. The potential of
the cell was controlled by an ADI Powerlab 4SP potientiostat.
Solutions were typically about 10−3 M in acetone with 0.1 M
tetrabutylammonium hexafluorophosphate (Bu4NPF6) as supporting
electrolyte and were purged with argon for approximately 5 min prior
to measurement. The default scanning rate was 100 mV s−1, and the
cyclic voltammograms were calibrated against the decamethylferroce-
nium/decamethylferrocene (Fc*) couple and are reported relative to
1488(s), 1415(s), 1252(s), 1223(s), 1065(s), 835(s), 766(s). Anal.
Calcd for C29H32O2: C, 84.43; H, 7.82. Found: C, 83.94; H, 7.97. HR-
ESI-MS: m/z 413.248 (100), 414.253 (25), 415.255 (4); calcd for [M
+ H]+ (C29H33O2) 413.248 (100), 414.251 (32), 415.254 (5). Crystals
of 2 suitable for an X-ray diffraction structural determination were
grown by slowly cooling a hot concentrated solution of 2 in MeOH.
2,6-Di(tert-butyl)-9,10-dihydroxy-4H-cyclopenta[def ]-
triphenylene (8). BBr3 (0.58 mL, 6.06 mmol) was added dropwise to a
solution of 2 (0.500 g, 1.21 mmol) in dry DCM (25 mL) at 0 °C. The
solution was warmed to rt and left to stir for 3 h, upon which the
excess BBr3 was quenched with MeOH (20 mL) added dropwise. An
additional 20 mL of DCM was added, the organic layer washed with
water and brine and dried over MgSO4, and the solvent removed in
1
vacuo to give 8 (0.458 g, 98%) as a white solid. H NMR (500 MHz,
CDCl3): δ 8.15 (s, 2H, H-1,7), 8.11 (s, 2H, H-8,11), 7.76 (s, 2H, H-
t
3,5), 5.47 (s, 2H, OH), 4.26 (s, 2H, H-4), 1.52 (s, 18H, Bu). 13C
G
dx.doi.org/10.1021/om5008852 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
NMR (126 MHz, CDCl3): δ 150.7, 143.4, 141.6, 134.9, 126.3, 125.2,
rt for 2 h, upon which HCl (60 mL, 0.2 M) was added. The organic
layer was extracted into DCM, washed with water and NH4Cl (sat),
and dried over MgSO4, and the solvent removed in vacuo. The crude
product was purified using column chromatography (50% DCM/PE)
to yield 10 (0.355 g, 97%) as a pale yellow solid. 1H NMR (500 MHz,
CDCl3): δ 7.56−7.50 (m, 2H, H-1,8), 7.33 (t, J = 7.5 Hz, 1H, H-2),
7.24−7.21 (m, 2H, H-3,7), 7.09 (td, J = 8.0, 1.0 Hz, 1H, H-6), 7.06−
7.00 (m, 4H, H-5,2′,5′,6′), 4.00 (s, 3H, OCH3), 3.96 (s, 2H, H-9),
3.86 (s, 3H, OCH3). 13C NMR (126 MHz, CDCl3): δ 148.8, 148.5,
144.0, 143.8, 141.7, 139.0, 137.7, 134.1, 128.9 (C-3), 126.5 (C-7),
126.4 (C-6), 126.3 (C-2), 124.9 (C-8), 124.0 (C-1), 123.2 (C-5/C-6′),
121.3 (C-5/C-6′), 112.6 (C-2′/C-5′), 111.3 (C-2′/C-5′), 56.1 (2 ×
120.0 (C-2,5), 115.2 (C-1,7), 109.9 (C-8,11), 37.8 (C-4), 36.0 (tBu,
̃
quat), 32.4 (tBu, CH3). IR: ν (cm−1) 3495(m), 3299(m), 2960(s),
1569(m), 1474(m), 1417(m), 1264(s), 1199(m), 851(s). HR-ESI-MS:
m/z 407.197 (100), 408.200 (31), 409.204 (10); calcd for [M + Na]+
(C27H28O2Na) 407.198 (100), 408.202 (30), 409.205 (5).
2,6-Di(tert-butyl)-9,10-ditriflyloxy-4H-cyclopenta[def ]-
triphenylene (9). Triflic anhydride (2.84 mL, 16.88 mmol) was added
dropwise to a solution of 8 (1.172 g, 3.05 mmol) and pyridine (1.5
mL, 18.6 mmol) in HPLC grade DCM (40 mL) at 0 °C. The solution
was stirred for 30 min and a further 10 min at rt, upon which HCl
(10%, 20 mL) was added. The yellow organic layer was washed with
water and NH4Cl (sat) and dried over MgSO4, and the solvent
removed in vacuo. The crude product was purified using column
chromatography (50% DCM/PE), yielding 9 (1.93 g, 97%) as a white
OCH3), 37.1 (C-9). IR: ν
̃
(cm−1) 3004(w), 2934(w), 1581(m),
1516(s), 1244(s), 1216(s), 1133(s), 810(m), 744(s), 598(m). Anal.
Calcd for C21H18O2: C, 83.42; H, 6.00. Found: C, 83.47; H, 5.93. HR-
ESI-MS: m/z 325.116 (100), 326.119 (24), 327.122 (3); calcd for [M
+ Na]+ (C21H18O2Na) 325.120 (100), 326.123 (23), 327.126 (3).
10,11-Dimethoxy-4H-cyclopenta[def ]triphenylene (4). A solution
of 10 (0.258 g, 0.85 mmol) in HPLC grade DCM (100 mL) was
purged with N2 for 10 min. With N2 gently bubbling, FeCl3 (0.553 g,
2.88 mmol) in nitromethane (3 mL) was added dropwise over 2 min.
The dark solution was stirred and bubbled for a further 13 min, upon
which the reaction was quenched with water (60 mL). The organic
layer was washed with water until the aqueous layer was colorless and
dried over MgSO4, and the solvent removed in vacuo to give a solid.
The crude solid was purified using column chromatography (40%
1
solid. H NMR (500 MHz, CDCl3): δ 8.64 (s, 2H, H-8,11), 8.21 (s,
2H, H-1,7), 7.93 (d, J = 1.0 Hz, 2H, H-3,5), 4.32 (s, 2H, H-4), 1.55 (s,
18H, tBu). 13C NMR (126 MHz, CDCl3): δ 152.0, 141.9, 138.4, 136.1,
132.2, 123.6, 122.8 (C-3,5), 119.0 (C-8,11), 118.9 (q, JCF = 320.5 Hz,
CF3), 115.8 (C-1,7), 37.7 (C-4), 36.1 (tBu, quat), 32.2 (tBu, CH3). IR:
ν
̃
(cm−1) 2963(m), 1412(s), 1212(s), 1132(s), 1104(s), 1019(m),
905(s), 848(s), 608(s). Anal. Calcd for C29H26F6O6S2: C, 53.70; H,
4.04. Found: C, 53.58; H, 3.95. HR-ESI-MS: m/z 671.094 (100),
672.095 (36), 673.099 (17), 674.101 (4); calcd for [M + Na]+
(C29H26F6O6S2) 671.097 (100), 672.100 (33), 673.097 (16),
674.094 (4).
1
2,6-Di(tert-butyl)-4H-cyclopenta[def ]triphenylene (3). Triethylsi-
lane (1.05 mL, 6.57 mmol) was added to a mixture of 9 (0.813 g, 1.25
mmol), Pd(OAc)2 (0.029 g, 0.13 mmol), and 1,3-bis-
(diphenylphosphino)propane (0.052 g, 0.13 mmol) in DMF (30
mL) at 60 °C under argon. The reaction mixture was stirred for 18 h,
then cooled to rt. The organic layer was extracted into ether, washed
with water and NaHCO3 (sat), and dried over MgSO4. The solvent
was removed in vacuo to give the crude product. Purification using
column chromatography (SiO2, 10% DCM/PE) yielded 3 (0.427 g,
DCM/PE), yielding 4 (0.223 g, 87%) as a white solid. H NMR (500
MHz, CDCl3): δ 8.19 (dd, J = 7.0, 1.5 Hz, 2H, H-1,7), 7.96 (s, 2H, H-
8,11), 7.70−7.64 (m, 4H, H-2,3,5,6), 4.30 (s, 2H, H-4), 4.14 (s, 6H,
OCH3). 13C NMR (126 MHz, CDCl3): δ 149.2 (C-9,10), 141.9,
136.8, 127.3 (C-2,3/C-6,5), 126.5, 125.1, 121.6 (C-2,3/C-6,5), 118.8
(C-1,7), 105.5 (C-8,11), 56.1 (OCH3), 37.7 (C-4). IR: ν
̃
(cm−1)
3016(w), 2960(w), 1615(m), 1540(m), 1433(s), 1257(m), 1163(m),
1062(m), 1041(m), 840(s), 757(s), 708(s). Anal. Calcd for C21H16O2·
0.2(CH3CH2OH): C, 83.03; H, 5.60. Found: C, 83.01; H, 5.52. HR-
ESI-MS: m/z 323.104 (100), 324.107 (24), 325.114 (4); calcd for [M
+ Na]+ (C21H16O2Na): 323.104 (100), 324.108 (23), 325.111 (3).
Crystals of 4 suitable for an X-ray diffraction structural determination
were grown by slowly cooling a hot concentrated solution of 4 in
EtOH.
1
97%) as a white solid. H NMR (500 MHz, CDCl3): δ 8.68 (dd, J =
6.0, 3.5 Hz, 2H, H-8,11), 8.35 (s, 2H, H-1,7), 7.83 (d, J = 1.0 Hz, 2H,
H-3,5), 7.69 (dd, J = 6.0, 3.5 Hz, 2H, H-9,10), 4.29 (s, 2H, H-4), 1.55
t
(s, 18H, Bu). 13C NMR (126 MHz, CDCl3): δ 150.8, 141.6, 135.5,
131.4, 126.6 (C-9,10), 125.6, 124.2 (C-8,11), 120.7 (C-3,5), 115.7 (C-
̃
1,7), 37.8 (C-4), 36.0 (tBu, quart), 32.4 (tBu, CH3). IR: ν (cm−1)
General Procedure for Complexation. A mixture of [Ru(μ3-
Cl)Cp*]4 (11) (0.060 g, 0.055 mmol), ligand (0.22 mmol),
deoxygenated THF (6 mL), and water (6 mL) were sealed in a 30
mL microwave tube under argon. The dark brown mixture was heated
in a microwave reactor at 130 °C for 15 min. Once cooled to rt, the
pale brown mixture was left open to air for 30 min, then filtered
through Celite, rinsing with water. Aqueous KPF6 (20 mL, sat) was
added to the solution, which was stirred for a further 30 min. The
mixture was extracted with DCM and washed with water. The solvent
was removed in vacuo to give the complex, which was purified via
column chromatography (10% MeOH/DCM), if needed, yielding
[RuCp*(η6-cyclopentatriphenylene)]PF6 as a white solid.
2944(s), 2899(s), 1596(m), 1415(s), 1361(m), 852(s), 762(s),
637(s). Anal. Calcd for C27H28: C, 91.99; H, 8.01. Found: C, 91.62;
H, 7.66. HR-ESI-MS: m/z 352.218 (100), 353.223 (42), 354.225 (9);
calcd for [M]+ (C27H28) 352.219 (100), 353.222 (30), 354.225 (4).
Crystals of 3 suitable for an X-ray diffraction structural determination
were grown by slowly cooling a hot, concentrated solution of 3 in
EtOH.
4H-Cyclopenta[def ]triphenylene (1). AlCl3 (0.158 g, 1.19 mmol)
was added to a solution of 3 (0.417 g, 1.18 mmol) in dry toluene (80
mL) under argon. The suspension was heated to 60 °C and stirred for
3 h. Upon cooling the reaction mixture, HCl (100 mL, 0.2 M) was
added. The organic layer was extracted into DCM, washed with water
and NH4Cl (sat), and dried over MgSO4, and the solvent removed in
vacuo. The crude product was purified using column chromatography
[RuCp*(η6-1)]PF6. Yield: 0.035 g, 26%. 31P NMR (162 MHz,
CD3C(O)CD3): δ −144.3 (sept, J = 707 Hz). IR: ν
̃
(cm−1) 2920(w),
2848(w), 1379(w), 1029(m), 836(s), 737(m), 557(s). Anal. Calcd for
C29H27F6PRu: C, 56.04; H, 4.38. Found: C, 56.26; H, 4.45. HR-ESI-
MS: m/z 471.115 (15), 472.116 (5), 473.114 (6), 474.113 (36),
475.112 (44), 476.113 (58), 477.112 (100), 478.115 (29), 479.113
(54), 480.116 (16); calcd for [M − PF6]+ (C29H27Ru): 471.118 (15),
472.122 (5), 473.117 (6), 474.117 (36), 475.116 (44), 476.117 (58),
477.116 (100), 478.119 (29), 479.117 (54), 480.120 (16). Crystals of
[RuCp*(η6-1)]PF6 suitable for an X-ray diffraction structural
determination were grown by vapor diffusion of ether into a
concentrated sample of [RuCp*(η6-1)]PF6 in acetone. Symmetrical
1
(SiO2, 10% DCM/PE) to yield 1 (0.264 g, 93%) as a white solid. H
NMR (500 MHz, CDCl3): δ 8.65 (dd, J = 7.0, 3.5 Hz, 2H, H-8,11),
8.33 (d, J = 8.0 Hz, 2H, H-1,7), 7.73 (dd, J = 7.0, 1.0 Hz, 2H, H-3,5),
7.72−7.67 (m, 4H, H-2,6,9,10) 4.31 (s, 2H, H-4). 13C NMR (126
MHz, CDCl3): δ 141.8, 137.4, 131.0, 127.5, 127.1, 126.9, 124.3 (C-
8,11), 122.6 (C-3,5), 119.5 (C-1,7), 37.6 (C-4). IR: ν
̃
(cm−1):
1434(m), 1402(m), 1231(w), 747(s), 623(m), 549(m). Anal. Calcd
for C19H12: C, 94.97; H, 5.03. Found: C, 94.74; H, 5.01. MALDI-TOF
MS: m/z 240.05 (100), 241.05 (36), 242.05 (7); calcd for [M]+
(C18H12) 240.09 (100), 241.10 (21), 242.10 (2). Crystals of 1 suitable
for an X-ray diffraction structural determination were grown by slowly
cooling a hot concentrated solution of 1 in MeOH.
1
isomer. H NMR (500 MHz, CD3C(O)CD3): δ 8.28 (d, J = 8.0 Hz,
2H, H-1,7), 7.95 (d, J = 7.5 Hz, 2H, H-3,5), 7.81 (t, J = 7.5 Hz, 2H, H-
2,6), 7.30 (dd, J = 6.0, 3.5 Hz, 2H, H-8,11), 6.42 (dd, J = 4.5, 2.5 Hz,
2H, H-9,10), 4.38 (s, 2H, H-4), 1.40 (s, 15H, Cp*). 13C NMR (126
MHz, CD3C(O)CD3): δ 143.2, 138.7, 129.7 (C-2,6), 126.9 (C-3,5),
123.8, 122.2 (C-1,7), 96.2 (Cp*-ring), 94.3, 88.9 (C-9,10), 83.4 (C-
4-(3,4-Dimethoxyphenyl)-9H-fluorene (10). AlCl3 (0.401 g, 3.01
mmol) was added to a solution of 5 (0.500 g, 1.21 mmol) in dry
toluene (100 mL) under argon. The orange suspension was stirred at
H
dx.doi.org/10.1021/om5008852 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
1
8,11), 38.2 (C-4), 9.3 (Cp*-CH3). Unsymmetrical isomer. H NMR
(500 MHz, CD3C(O)CD3): δ 8.76 (d, J = 7.5 Hz, 1H, H-7), 8.55 (d, J
= 7.5 Hz, 1H, H-11), 8.47 (d, J = 7.5 Hz, 1H, H-8), 7.94−7.82 (m, 4H,
H-5, 6, H-9, H-10), 7.16 (d, J = 6.0 Hz, 1H, H-1), 6.72 (d, J = 5.5 Hz,
1H, H-3), 6.20 (t, J = 5.5 Hz, 1H, H-2), 4.34 (d, J = 21.5 Hz, 1H, H-
4b), 4.14 (d, J = 21.5 Hz, 1H, H-4a), 1.32 (s, 15H, Cp*). 13C NMR
(126 MHz, CD3C(O)CD3): δ 142.5, 133.4, 133.2, 131.7, 131.1, 129.6,
129.2, 127.7, 127.0 (C-11), 126.1 (C-7), 125.7, 121.8 (C-8), 104.1,
100.8, 95.1 (Cp*-ring), 92.7, 87.7 (C-2), 86.4 (C-3), 80.6 (C-1), 36.8
(C-4), 8.8 (Cp*-CH3).
[RuCp*OH(η6-4)]PF6. H NMR (500 MHz, CD3C(O)CD3): δ 8.45
(m, 1H, H-6), 8.20 (s, 1H, H-8), 8.00 (s, 1H, H-11), 7.83−7.79 (m,
2H, H-5,6), 7.27 (d, J = 6.0 Hz, 1H, H-1), 6.71 (d, J = 5.5 Hz, 1H, H-
3), 6.18 (t, J = 5.5 Hz, 1H, H-2), 4.34 (d, J = 21.0 Hz, 1H, H-4b), 4.18
(d, J = 21.0 Hz, 1H, H-4a), 4.14 (s, 3H, OCH3-9), 4.09 (s, 3H, OCH3-
10), 3.87 (m, 2H, CpCH2-1′), 1.47 (s, 3H, CpCH3-2′/5′), 1.39 (s, 3H,
CpCH3-2′/5′), 1.23 (s, 3H, CpCH3-3′/4′), 1.19 (s, 3H, CpCH3-3′/
4′). 13C NMR (126 MHz, CD3C(O)CD3): δ 152.62 (C-9), 151.37
(C-10), 142.45 (C-4a), 132.85, 131.53 (C-5/6), 129.47, 127.53,
124.55 (C-5/6), 121.50 (C-7), 120.63, 108.73 (C-11), 107.90 (C-8),
104.33 (C-3a), 100.70, 95.64 (Cp-ring), 95.61 (Cp-ring), 95.50 (Cp-
ring), 95.07 (Cp-ring), 94.95 (Cp-ring), 93.94, 87.08 (C-2), 85.57 (C-
3), 80.06 (C-1), 56.75 (OCH3-10), 56.54 (OCH3-9), 55.05
(CpCH2OH), 37.10 (C-4), 8.88 (CpCH3-2′/5′), 8.87 (CpCH3-2′/
5′), 8.46 (2 × CpCH3-3′,4′). 31P NMR (162 MHz, CD3C(O)CD3): δ
[RuCp*(η6-2)]PF6. Yield: 0.043 g, 27%. 1H NMR (500 MHz,
CD3C(O)CD3): δ 8.42 (s, 2H, H-1,7), 8.04 (s, 2H, H-3,5), 7.46 (s,
2H, H-8,11), 4.40 (d, J = 21.5 Hz, 1H, H-4), 4.33 (d, J = 21.5 Hz, 1H,
H-4), 4.18 (s, 6H, OCH3), 1.53 (s, 18H, tBu), 1.34 (s, 15H, Cp*). 13
C
NMR (126 MHz, CD3C(O)CD3): δ 153.4, 142.9, 136.5, 124.8, 124.0
(C-3,5), 123.1, 119.1 (C-1,7), 94.5 (Cp*-ring), 91.1, 70.9 (C-8,11),
58.3 (OCH3), 38.4 (C-4), 36.7 (tBu, quart), 32.3 (tBu, CH3), 9.0
(Cp*-CH3). 31P NMR (162 MHz, CD3C(O)CD3): δ −144.3 (sept,
−144.3 (sept, JPF = 707 Hz). IR: ν
̃
(cm−1) 3582(m), 2948(w),
1611(m), 1538(m), 1268(m), 1212(m), 830(s), 762(s), 555(s). Anal.
Calcd for C31H31F6O3PRu: C, 53.37; H, 4.48. Found: C, 53.78; H,
4.58. HR-ESI-MS: m/z 547.133 (14), 548.132 (5), 549.130 (7),
550.131 (36), 551.129 (45), 552.131 (60), 553.130 (100), 554.132
(31), 555.131 (55), 556.134 (16), 557.135 (3); calcd for [M − PF6]+
(C31H31ORu) 547.134 (14), 548.132 (5), 549.133 (6), 550.133 (35),
551.132 (45), 552.133 (58), 553.132 (100), 554.135 (31), 555.133
(54), 556.136 (17), 557.139 (3). Crystals of [RuCp*OH(η6-4)]PF6
suitable for an X-ray diffraction structural determination were grown
by vapor diffusion of ether into a concentrated sample of
[RuCp*OH(η6-4)]PF6 in acetone.
JPF = 707 Hz). IR: ν
̃
(cm−1) 2958(m), 1415(m), 1266(m), 1200(m),
838(s), 765(m), 556(s). Anal. Calcd for C39H47F6O2PRu: C, 59.01; H,
5.97. Found: C, 58.77; H, 6.17. HR-ESI-MS: m/z 643.262 (13),
644.261 (6), 645.263 (6), 646.262 (33), 647.260 (45), 648.262 (60),
649.261 (100), 650.263 (38), 651.261 (54), 652.265 (20), 653.266
(4); calcd for [M − PF6]+ (C39H47O2Ru): 643.265 (14), 644.268 (6),
645.264 (6), 646.263 (34), 647.263 (45), 648.263 (59), 649.262
(100), 650.265 (38), 651.263 (54), 652.266 (21), 653.269 (4).
Crystals of [RuCp*(η6-2)]PF6 suitable for an X-ray diffraction
structural determination were grown by vapor diffusion of ether into
a concentrated sample of [RuCp*(η6-2)]PF6 in DCM.
[RuCp*(η6-3)]PF6. Yield: 0.090 g, 55%. 1H NMR (500 MHz,
CD3C(O)CD3): δ 8.38 (s, 2H, H-1,7), 8.08 (s, 2H, H-3,5), 7.50 (dd, J
= 4.5, 2.5 Hz, 2H, H-8,11), 6.41 (dd, J = 4.5, 2.5 Hz, 2H, H-9,10), 4.42
(d, J = 21.5 Hz, 1H, H-4), 4.35 (d, J = 21.5 Hz, 1H, H-4), 1.54 (s,
18H, tBu), 1.40 (s, 15H, Cp*). 13C NMR (126 MHz, CD3C(O)CD3):
δ 153.5, 143.0, 136.8, 124.5 (C-3,5), 122.8, 119.0 (C-1,7), 96.0, 94.9
(Cp*-ring), 88.7 (C-9,10), 83.5 (C-8,11), 38.4 (C-4), 36.7 (tBu,
quart), 32.3 (tBu, CH3), 9.2 (Cp*-CH3). 31P NMR (162 MHz,
X-ray Crystallography. Crystallographic data collection and
refinement details for 1−4, [RuCp*(1,2,4)]PF6, and [RuCp*OH(4)]-
PF6 are reported in Table S1 in the Supporting Information. Data were
collected on an Agilent SuperNova with Atlas CCD using mirror
monochromated microfocus Cu Kα radiation (λ = 1.541 84 Å) at 40
W. The data processing was undertaken within CrysAlisPro,48
including a numerical absorption correction over a face-indexed
model and/or a multiscan empirical correction. The structures were
solved by direct methods with SHELXS-9749,50 and extended and
refined against all F2 data with SHELXL-9749,50 using the X-Seed
interface.51 The non-hydrogen atoms in the asymmetric unit were
modeled with anisotropic displacement parameters. Hydrogen atoms
were placed in calculated positions and refined using a riding model
with fixed C−H distances (sp2-CH 0.95 Å, sp3-CH3 0.98 Å, sp3-CH2
0.99 Å) and isotropic displacement parameters estimated as Uiso(H) =
1.2Ueq(C), except for CH3, where Uiso(H) = 1.5Ueq(C). Special
conditions/variations to the general procedure are given below.
2: The fine needle crystals did not diffract strongly, some appearing
to be twinned based on the diffraction pattern during screening and
poor agreement with the best cell. Full collection was undertaken on a
small specimen, resulting in weak data that refined with relatively high
residuals (R1 = 11.2%).
[RuCp*(1)]PF6: The asymmetric unit contains the complex cation, a
PF6 anion, along with an acetone molecule on a mirror plane. The
solution appeared to fit the unsymmetrical RuCp* complex; however,
there was significant electron density in a bay position opposite the
metal, suggesting a methylene bridge at this site. A disordered model
with two complete cations was refined with rotation of the
cyclopentatriphenylene by ca. 120°, and the Cp* by ca. 35°. This
model is consistent with the cocrystallization of both isomeric
products (refining to 70% unsymmetric, 30% symmetric), with the
Ru atom approximately co-sited for both. Extensive use of restraints
ensured the two components had similar and sensible geometric
parameters; SAME restraints across the two cyclopentatriphenylenes
and two Cp* orientations were used, along with FLAT restraints for
the Cp* rings and some benzenoid rings. Most of the electron density
was accounted for using this approach, although atomic precision is
low.
CD3C(O)CD3): δ −144.3 (sept, JPF = 707 Hz). IR: ν
̃
(cm−1) 2923(s),
2853(m), 1735(m), 1255(m), 1029(m), 844(s), 557(s). Anal. Calcd
for C37H43F6PRu: C, 60.56; H, 5.91. Found: C, 60.57; H, 6.01. HR-
ESI-MS: m/z 583.237 (14), 584.240 (6), 585.235 (6), 586.237 (34),
587.237 (45), 588.238 (59), 589.237 (100), 590.238 (38), 591.237
(54), 592.239 (20), 593.240 (4); calcd for [M − PF6]+ (C37H42Ru):
583.244 (14), 584.247 (6), 585.243 (6), 586.232 (34), 587.232 (45),
588.232 (59), 589.231 (100), 590.244 (36), 591.242 (54), 592.235
(20), 593.238 (4).
[RuCp*(η6-4)]PF6. Yield: 0.048 g, 32%. 1H NMR (500 MHz,
CD3C(O)CD3): δ 8.47 (m, 1H, H-7), 8.25 (s, 1H, H-8), 8.04 (s, 1H,
H-11), 7.84−7.79 (m, 2H, H-5,6), 7.25 (d, J = 6.0 Hz, 1H, H-1), 6.67
(d, J = 5.5 Hz, 1H, H-3), 6.15 (t, J = 6.0 Hz, 1H, H-2), 4.35 (d, J =
21.5 Hz, 1H, H-4b), 4.16 (d, J = 21.5 Hz, 1H, H-4a), 4.15 (s, 3H,
OCH3-9), 4.10 (s, 3H, OCH3-10), 1.35 (s, 15H, Cp*). 13C NMR (126
MHz, CD3C(O)CD3): δ 152.6 (C-9), 151.4 (C-10), 142.4 (C-4a),
131.4 (C-5/C-6), 129.5, 127.6, 124.5 (C-5/C-6), 121.5 (C-7), 120.7,
108.8 (C-11), 108.0 (C-8), 103.9 (C-3a), 100.4, 97.8, 94.8 (Cp*-ring),
93.8, 87.4 (C-2), 85.8 (C-3), 80.3 (C-1), 56.8 (OCH3-10), 56.5
(OCH3-9), 36.8 (C-4), 8.9 (Cp*-CH3). 31P NMR (162 MHz,
CD3C(O)CD3): δ −144.3 (sept, JPF = 708 Hz). IR: ν
̃
(cm−1)
3096(w), 2918(w), 1610(m), 1390(m), 1211(m), 830(s), 555(s).
Anal. Calcd for C31H31F6O2PRu: C, 54.63; H, 4.58. Found: C, 54.97;
H, 4.61. HR-ESI-MS: m/z 531.139 (14), 532.143 (4), 533.139 (5),
534.138 (36), 535.137 (43), 536.138 (61), 537.136 (100), 538.140
(31), 539.137 (52), 540.141 (17), 541.144 (3); calcd for [M − PF6]+
(C31H31O2Ru): 531.139 (15), 532.143 (5), 533.138 (6), 534.138 (35),
535.137 (45), 536.138 (58), 537.137 (100), 538.140 (31), 539.138
(54), 540.141 (17), 541.144 (3). Crystals of [RuCp*(η6-4)]PF6
suitable for an X-ray diffraction structural determination were grown
by vapor diffusion of ether into a concentrated sample of [RuCp*(η6-
4)]PF6 in acetone.
I
dx.doi.org/10.1021/om5008852 | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(20) Schmid, A.; Lindel, T. Angew. Chem., Int. Ed. 2004, 43, 1581.
(21) Yamamoto, M.; Onitsuka, K.; Uno, M.; Takahashi, S. J. Chem.
Soc., Dalton Trans. 2002, 1473.
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Chem. Soc. 2005, 127, 11580.
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Stimson, L. M.; Howard, J. A. K.; Marder, T. B. New J. Chem. 2001, 25,
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(25) Karslyan, E. E.; Konovalov, A. I.; Borissova, A. O.; Petrovskii, P.
V.; Kudinov, A. R. Mendeleev Commun. 2011, 21, 309.
ASSOCIATED CONTENT
* Supporting Information
■
S
1H and 13C NMR spectra for 1−5, 8−10, and all complexes, 2D
NOESY spectrum for [RuCp*(4)]PF6, ORTEP diagrams for
1−4 and packing diagrams for 1−4, and [RuCp*OH(4)]PF6, a
table of X-ray crystallographic data and structure refinement
parameters (along with CIFs), table of selected bond lengths
for the ligands and complexes, and variable scan rate cyclic
voltammograms for 2 and 3. This material is available free of
charge via the Internet at http://pubs.acs.org. Full details of the
structure determinations have also been deposited with the
Cambridge Crystallographic Data Centre (www.ccdc.cam.ac.
uk) as CCDC Nos. 1021293−1021300.
(26) Chavez, I.; Otero, M.; Roman
Chem. 1992, 427, 369.
́
, E.; Muller, U. J. Organomet.
̈
(27) Fairchild, R. M.; Holman, K. T. Organometallics 2008, 27, 1823.
(28) Steiner, T. Angew. Chem., Int. Ed. 2002, 41, 48.
(29) Gusev, O. V.; Ievlev, M. A.; Peterleitner, M. G.; Peregudova, S.
M.; Denisovich, L. I.; Petrovskii, P. V.; Ustynyuk, N. A. J. Organomet.
Chem. 1997, 534, 57.
AUTHOR INFORMATION
Corresponding Author
*E-mail: nlucas@chemistry.otago.ac.nz.
Notes
■
(30) Mohapatra, S. K.; Romanov, A.; Timofeeva, T. V.; Marder, S. R.;
Barlow, S. J. Organomet. Chem. 2014, 751, 314.
The authors declare no competing financial interest.
(31) Gusev, O. V.; Ievlev, M. A.; Peganova, T. y. A.; Peterleitner, M.
G.; Petrovskii, P. V.; Oprunenko, Y. F.; Ustynyuk, N. A. J. Organomet.
Chem. 1998, 551, 93.
(32) Gusev, O. V.; Peterleitner, M. G.; Ievlev, M. A.; Kal’sin, A. M.;
Petrovskii, P. V.; Denisovich, L. I.; Ustynyuk, N. A. J. Organomet.
Chem. 1997, 531, 95.
(33) Gusev, O. V.; Denisovich, L. I.; Peterleitner, M. G.; Rubezhov,
A. Z.; Ustynyuk, N. A.; Maitlis, P. M. J. Organomet. Chem. 1993, 452,
219.
ACKNOWLEDGMENTS
■
Support from the University of Otago [including a Post-
graduate Publishing Bursary (BRH), Ph.D. Scholarship (CBL),
University of Otago Research Grant] and The MacDiarmid
Institute for Advanced Materials and Nanotechnology is
gratefully acknowledged.
(34) Mohapatra, S. K.; Romanov, A.; Angles, G.; Timofeeva, T. V.;
Barlow, S.; Marder, S. R. J. Organomet. Chem. 2012, 706−707, 140.
(35) de Denus, C. R.; Baker, P.; Toner, J.; McKevitt, S.; Todd, E. K.;
Abd-El-Aziz, A. S. Macromol. Symp. 2003, 196, 113.
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dx.doi.org/10.1021/om5008852 | Organometallics XXXX, XXX, XXX−XXX