Highly fluorescent complexes with gold, palladium or platinum linked to perylene through a tetrafluorophenyl group

Article abstract of DOI:10.1039/c3dt32843k

Treatment of 3-(1-hexynyl)perylene with Co₂(CO)₈ resulted in the formation of the dinuclear cobalt complex [Co ₂(CO)₆(μ-η²-C₄H ₉CC-Per)] (Per = 3-perylenyl) (1). The perylene derivatives 3-(2,3,5,6-tetrafluorophenyl)perylene (PerC₆F₄H) and 3-(2,3,5,6-tetrafluorophenyl)-9(10)hexylperylene (C₆-PerC ₆F₄H) were prepared and used to synthesize [AuR(CN ^tBu)] (R = PerC₆F₄2a), [AuR(CN(C ₆H₂)-3,4,5-(OC₁₂H₂₅)₃)] (R = PerC₆F₄ (3a), R = C₆-PerC ₆F₄ (3b)), trans-[PdR(PR′₃)₂X] (R = PerC₆F₄, R′ = Ph, X = I (4a)); (R = C ₆-PerC₆F₄, R′ = Ph, X = I (4b)); (R = PerC₆F₄, R′ = Et, X = I (5a)); (R = C ₆-PerC₆F₄, R′ = Et, X = I (5b)); (R = PerC₆F₄, R′ = Ph, X = NCS (6a)), and trans-[Pd(PerC₆F₄)(PEt₃)₂X] (X = Br (7a); X = I (8a)). The molecular structure of complexes 1, 2a, and 6a has been determined by X-ray diffraction analysis. The perylenyl fragments of complexes 2a or 6a are essentially planar and make dihedral angles to the tetrafluorophenyl plane of 57.49° (2a) and 77.75° (6a). No π-π stacking of perylenyl rings is observed in any of the three molecules, but 2a shows association of two monomers (arranged almost antiparallel), with an Au...Au distance of 3.114 A. DFT calculations were performed on the absorption spectra of representative PerC₆F₄Y (Y = H, F, Au(CNMe), PtBr(PMe₃)₂ and PdBr(PMe₃) ₂). All complexes exhibit fluorescence associated with the perylene fragment with emission quantum yields, in solution at room temperature, in the range 0.20-0.90 and emission lifetimes ～4 ns, and no significant differences in the emission maxima, due to an efficient electronic decoupling of the metal fragment from the HOMO and LUMO of the perylene chromophore. The latter is confirmed by DFT calculations.

Full text of DOI:10.1039/c3dt32843k

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Highly fluorescent complexes with gold, palladium
or platinum linked to perylene through a
tetrafluorophenyl group†
Cite this: DOI: 10.1039/c3dt32843k
Sergio Lentijo,a Gabriel Aullón,b Jesús A. Miguel*a and Pablo Espinet*a
Treatment of 3-(1-hexynyl)perylene with Co2(CO)8 resulted in the formation of the dinuclear cobalt
complex [Co2(CO)6(μ–η2-C4H9CuC-Per)] (Per = 3-perylenyl) (1). The perylene derivatives 3-(2,3,5,6-tetrafl-
uorophenyl)perylene (PerC6F4H) and 3-(2,3,5,6-tetrafluorophenyl)-9(10)hexylperylene (C6-PerC6F4H) were
prepared and used to synthesize [AuR(CNtBu)] (R = PerC6F4 2a), [AuR(CN(C6H2)-3,4,5-(OC12H25)3)] (R =
PerC6F4 (3a), R = C6-PerC6F4 (3b)), trans-[PdR(PR’3)2X] (R = PerC6F4, R’ = Ph, X = I (4a)); (R = C6-PerC6F4,
R’ = Ph, X = I (4b)); (R = PerC6F4, R’ = Et, X = I (5a)); (R = C6-PerC6F4, R’ = Et, X = I (5b)); (R = PerC6F4, R’ =
Ph, X = NCS (6a)), and trans-[Pd(PerC6F4)(PEt3)2X] (X = Br (7a); X = I (8a)). The molecular structure of com-
plexes 1, 2a, and 6a has been determined by X-ray diffraction analysis. The perylenyl fragments of com-
plexes 2a or 6a are essentially planar and make dihedral angles to the tetrafluorophenyl plane of 57.49°
(2a) and 77.75° (6a). No π–π stacking of perylenyl rings is observed in any of the three molecules, but 2a
shows association of two monomers (arranged almost antiparallel), with an Au⋯Au distance of 3.114 Å.
DFT calculations were performed on the absorption spectra of representative PerC6F4Y (Y = H, F,
Au(CNMe), PtBr(PMe3)2 and PdBr(PMe3)2). All complexes exhibit fluorescence associated with the
perylene fragment with emission quantum yields, in solution at room temperature, in the range
0.20–0.90 and emission lifetimes ∼4 ns, and no significant differences in the emission maxima, due to
an efficient electronic decoupling of the metal fragment from the HOMO and LUMO of the perylene
chromophore. The latter is confirmed by DFT calculations.
Received 27th November 2012,
Accepted 9th January 2013
DOI: 10.1039/c3dt32843k
www.rsc.org/dalton
inertness. Fluoroaryls are also better π-acceptors when bonded
to suitable electron-rich metal centers. The result is that
Introduction
For years several groups have shown the advantages of fluori- fluoroaryls allow for isolation of stable organometallic com-
nated aryl ligands to isolate and study organometallic com- plexes, including some, otherwise difficult to observe, inter-
plexes of transition metals, such as Pt or Pd,1 Ag,2 and Au.3 In mediates in important catalytic processes.4
general, M–aryl bonds are weaker and more reactive ligands
We have recently reported platinum organometallic com-
than the analogous M–fluoroaryl bonds. The higher polarity of plexes of perylene with Pt directly σ-bonded to the 3 position
the latter M–C bond contributes to its higher strength and of the perylene core, and studied how the coordination of
platinum affects the photophysical properties of the material.5
It was found that the coordination of Pt has only a moderate
quenching effect on the fluorescence (these organoplatinum
complexes show intense fluorescence, about 70–80% that of
the mother organic molecule), in spite of the fact that directly
attaching metal centers to aromatic cores of organic chromo-
pheres is often very detrimental for fluorescence.6,7
aIU CINQUIMA Química Inorgánica, Facultad de Ciencias, Universidad de
Valladolid, E-47071 Valladolid, Spain. E-mail: espinet@qi.uva.es
bDepartament de Química Inorgànica, Universitat de Barcelona, Martí i Franquès
1-11, E-08028 Barcelona, Spain
†Electronic supplementary information (ESI) available: Selected interatomic dis-
tances (Å) and angles (°) for the second molecule of complex 1 and a view of the
Frequently, the optical properties are noticeably modified
upon changing the metals in the material. We wanted to know
the effect of replacing Pt by Pd or Au in a common perylene
skeleton, but the direct bonds of Pd or Au to perylene are not
stable enough to isolate the corresponding complexes, study
their optical properties, and compare them with the Pt com-
plexes. Thus, we decided to obtain perylene derivatives with
two different molecules of 1, absorption and emission spectra of 8 in different
solvents, cyclic voltammogram of compounds 2a, 4a and 4b, fluorescence decays
for 4a and 4b, calculated absorption spectra parameters for PerC6F4-Y com-
pounds (in gas phase and chloroform solution), and schematic representation of
the main electronic transitions expected in the absorption spectra for
PerC6F4MBr(PMe3)2 with M = Pd or Pt. CCDC 870559, 870560, 870561. For
ESI and crystallographic data in CIF or other electronic format see DOI:
10.1039/c3dt32843k
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gold, palladium or platinum attached to perylene through a The IR spectrum shows three strong absorptions at 2086, 2050
tetrafluorophenyl link, by functionalizing the perylene mole- and 2022 cm−1 for the terminal carbonyl groups, in the
cule with a tetrafluorophenyl group and submitting it to metal- expected range for similar η2-alkyne adducts containing a
lation with Au, Pd or Pt moieties. The presence of the C6F4MLn Co2(CO)6 fragment.9,10 The 1H NMR spectrum of 1 in CDCl3
substituent (M = Au, Pd, Pt) could be an efficient entry to new shows deshielding of the signals of the CαC–CH2 group
structural and functional motifs, significantly widening the (3.32 ppm) as compared with 3-(1-hexynyl)perylene (2.60 ppm).
diversity of photofunctional systems available. As discussed The structure of 1 was unequivocally confirmed by X-ray
below, the C6F4 link turned out to be rather efficient to electro- crystallography (see below).
nically disconnect the MLn from the perylenyl fragment.
The hydrogenation of 3-(1-hexynyl)perylene in THF yielded
literature pro-
Since a problem in the study of perylene derivatives is the 3-hexylperylene quantitatively. Following
a
poor solubility of the compounds, our strategy also included cedure,11 3-hexylperylene was brominated with NBS in DMF
enhancing the solubility by incorporating appropriate ligands to yield a 1 : 1 mixture of isomers 3-bromo-9-hexyl- and
to the metal center. An additional strategy for solubilization 3-bromo-10-hexylperylene, which could not be separated.
has been to attach an alkyl (hexyl) substituent on the perylene
Coupling of 3-bromoperylene with tetrafluorophenylboronic
core. This second strategy is more synthetically demanding, acid, following a literature procedure for highly inactive fluoro-
and leads to mixtures of isomers. Gold(I), palladium(II) and phenylboronic acids,12 produced very low yield (5%) of
platinum(II) complexes with the tetrafluorophenylperylenyl 3-(2,3,5,6-tetrafluorophenyl)perylene (PerC6F4H). Much more
and C6-tetrafluorophenylperylenyl fragments have been effective was a procedure described for intermolecular direct
prepared. Since 3-(1-hexynyl)perylene was an intermediate arylation of electron-deficient arenes,13 which yielded more
in the synthesis of C6-tetrafluorophenylperylene, it was used than 50% of the coupling product PerC6F4H, impurified with
to prepare another structural type, the corresponding 3–5% of perylene, as a yellow solid. Identical conditions
[Co2(CO)6(μ–η2-C4H9CuC-Per)] (Per = 3-perylenyl).
were used to obtain a mixture of isomers 3-tetrafluorophenyl-
9-hexylperylene and 3-tetrafluorophenyl-10-hexylperylene
(C6-PerC6F4H) as a yellow solid, clearly more soluble in common
organic solvents than PerC6F4H.
The 1H NMR spectrum of PerC6F4H shows the signal of
C6F4H as a multiplet at 7.21 ppm, whereas the 19F NMR spec-
trum displays two sets of multiplets (AA′XX′Z spin system) at
Results and discussion
Synthesis and characterization
3-(1-Hexynyl)perylene was prepared by a Sonogashira coupling
of 3-bromoperylene with 1-hexine, following a similar litera-
ture procedure.8 Treatment of 3-(1-hexynyl)perylene with
Co2(CO)8 in dichloromethane at room temperature, for 2 h,
resulted in the formation of the dinuclear Co complex 1
(Scheme 1). This dark olive green complex is soluble in
organic solvents such as chloroform, dichloromethane,
toluene, acetone and THF, but insoluble in hexane or alcohols.
1
−139.1 and −140.2 ppm. The aromatic region in the H NMR
spectrum of C6-PerC6F4H is complex because of the presence
of the two substitutional isomers; in addition, it displays a
multiplet at 7.38 ppm for C6F4H, and the signals of the alkyl
chain attached to perylene: one triplet at 3.05 ppm for the CH2
group bonded directly to perylene, and the remaining alkyl
chain H atoms as unresolved signals in the range 0.8–1.8 ppm.
As expected, the 19F NMR spectrum is very similar to that of
PerC6F4H.
The bromo or iodo derivatives of R-PerC6F4H (R = H, C6)
were obtained by treating a solution of R-PerC6F4H, in THF at
−70 °C, with BuLi, and subsequently adding Br2 or I2, respecti-
vely (Scheme 2). The compounds obtained were contaminated
with perylene (<5%), but were used as such in the subsequent
reactions with metal centers, as it is easier to purify the com-
1
plexes than the precursor. As expected, the H NMR spectra of
the complexes showed the disappearance of the proton of the
fluoroaromatic group, and the 19F NMR spectra displayed AA′
XX′ spin system for the C6F4X moiety, with two groups of
signals corresponding to the Fortho and the Fmeta atoms.
The gold(I) isocyanide complexes 2a and 3a,b were obtained
in two steps by arylation of [AuCl(tht)] followed by ligand
exchange with isocyanide. Their IR spectra show one ν(CuN)
absorption at 2226 cm−1 for 2a, and at 2213 cm−1 for 3a,b, at
higher wavenumbers than for the free isocyanide, as an effect
of coordination to gold(I).3a,14 The 1H NMR spectra of the
gold(I) isocyanide complexes show the signals of the corres-
ponding isocyanide, and the 19F NMR spectra show two
Scheme 1 (i) Pd(OAc)2 (5 mol%), PtBuMe–HBF4 (10 mol%), K2CO3 (1.1 equiv.),
DMA, 120 °C; (ii) 1-hexyne, Pd2dba3, PPh3, CuI.
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Scheme 2 (i) 1. BuLi; 2. ClAu(tht); (ii) 1. BuLi; 2. X2.
complex multiplets corresponding to an AA′XX′ system. Com-
plexes 3a,b were hoped to display mesogenic properties, as
found for some purely organic perylene diimide compounds.15
The compounds have fairly low melting points, but are not
mesomorphic.
The phosphine complexes 4a,b, 5a, 7a and 8a were easily
prepared in good yield, as yellow solids, by oxidative addition
of R-PerC6F4X (R = H, C6H13; X = Br, I) to an appropriate Pd(0)
or Pt(0) precursor. Metathesis of 4a with one molar equivalent
of KSCN leads to 6a, for which the value 2081 cm−1 for
ν(CuN) suggests N-coordination of the thiocyanato ligand.16
This was confirmed by X-ray diffraction methods (see later).
These palladium derivatives are yellow solids, and are more
soluble than the starting organic precursors. The 1H NMR
Fig. 1 ORTEP of the crystal structures of 1, 2a, and 6a. The ellipsoids are
spectra of the complexes show the expected resonances as shown at 30% probability (H atoms are omitted for clarity).
above. The 31P{1H} NMR spectra of the Pd complexes 4–6
show a singlet, consistent with a trans arrangement of the
Table 1 Selected interatomic distances (Å) and angles (°) for 1. Data for the
second molecule are given in the ESI
two phosphines. The 19F NMR spectra show two complicated
multiplets, in the range −116 and −119 ppm for Fortho and
ca. −142 ppm for Fmeta, by coupling to the two 31P atoms
(AA′MM′X2 system). The 31P{1H} NMR spectra of the platinum
complexes are also consistent with a trans arrangement of
the two phosphines and show a singlet with 195Pt satellites, at
Co(1)–Co(2)
Co(1)–C(22)
Co(1)–C(21)
Co(2)–C(21)
Co(2)–C(22)
C(21)–C(22)
C(22)–C(23)
2.459(2)
1.974(8)
2.001(8)
1.971(8)
1.951(8)
1.337(10)
1.520(10)
C(1)–C(21)
C(31)–O(1)
C(32)–O(2)
C(33)–O(3)
C(34)–O(4)
C(35)–O(5)
C(36)–O(6)
1.473(10)
1.139(9)
1.134(10)
1.133(10)
1.146(9)
1.141(10)
1.149(10)
1
ca. 13.8 ppm for 7a and 33.0 ppm for 8a. The JPtP values
(2440 Hz) are in the range for a trans-P–Pt–P configuration.5,17
The 19F NMR spectra show two multiplet signals (as for Pd)
further complicated with 195Pt satellites, at ca. −119.2 ppm
(JPt–F = 446 Hz) for Fortho and −142.7 ppm (JPt–F = 120 Hz) for
C(22)–Co(1)–Co(2)
C(21)–Co(1)–Co(2)
C(22)–Co(2)–Co(1)
C(21)–Co(2)–Co(1)
50.8(2)
51.2(2)
51.6(2)
52.3(2)
C(1)–C(21)–Co(2)
C(1)–C(21)–Co(1)
C(21)–C(22)–Co(2)
C(21)–C(22)–Co(1)
131.8(5)
136.1(5)
70.9(5)
71.5(5)
Fmeta
.
X-ray crystal structures
Data collection and refinement parameters are given in the
Experimental section.
The structures of 1, 2a, and 6a were determined by single-
crystal X-ray diffraction methods, and are shown in Fig. 1.
Selected bond lengths and angles are given in Tables 1 and 2.
ˉ
Complex 1 crystallizes in the triclinic space group P1, with
two molecules per asymmetric being chemically equivalent,
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of 3.114 Å, which is within the range proposed for aurophilic
interactions.22
Table 2 Selected interatomic distances (Å) and angles (°) for 2a and for 6a
2a
6a
In complex 6a, the Pd(II) center shows a slightly distorted
square planar geometry. Confirming the spectroscopic studies,
the PEt3 ligands are in trans configuration, with a P(1)–Pd–P(2)
angle of 174.4°. As expected, the thiocyanate is N-bonded, with
C(27)–N(1)–Pd and N(1)–C(27)–S(1) bond angles only slightly
deviated from linearity (167.8(5)° and 174.1(6)°, respectively).
The Pd–N distance (2.131(6) Å) is longer than those found in
most thiocyanato-palladium(II) complexes, reflecting the high
trans-influence of the tetrafluorophenyl group.23
Finally, the potential π–π stacking aggregation of molecules,
often found for organic compounds with extended aromatic
cores, is not observed for any of the complexes, which helps
for the higher solubility observed.
Au(1)–C(1)
Au(1)–C(27)
C(27)–N(1)
N(1)–C(28)
1.999(12)
1.964(13)
1.115(15)
1.502(18)
Pd(1)–C(1)
Pd(1)–P(1)
Pd(1)–P(2)
Pd(1)–N(1)
N(1)–C(27)
C(27)–S(1)
C(1)–Pd(1)–N
C(1)–Pd(1)–P(1)
N–Pd(1)–P(1)
C(1)–Pd(1)–P(2)
N–Pd(1)–P(2)
P(1)–Pd(1)–P(2)
N(1)–C(27)–S(1)
C(27)–N(1)–Pd(1)
C(2)–C(1)–C(6)
2.000(4)
2.3617(13)
2.3239(13)
2.131(6)
0.937(6)
1.724(5)
176.15(17)
90.78(12)
91.57(11)
91.12(12)
86.82(11)
174.44(4)
174.1(6)
C(27)–Au(1)–C(1)
N(1)–C(27)–Au(1)
C(27)–N(1)–C(28)
C(2)–C(1)–C(6)
178.1(5)
179.4(14)
179.4(17)
112.7(11)
167.8(5)
113.2(4)
Photophysical studies
(a) UV-Vis absorption spectra. The UV-Vis absorption and
emission spectra of dilute solutions of the metal complexes in
chloroform (c ∼ 10−5 M) are summarized in Table 3. On the
other hand, the absorption spectra of perylene, Per-
CuC–C4H9, PerC6F4H, and C6-PerC6F4H are compared with
those of complexes 1–8 in Fig. 3, to see the influence of the
chain or the C6F4MLn group on the photophysical properties
as compared to perylene.
Fig. 2 Molecular arrangement into dimers in the crystal structure of 2a.
The profiles of the UV-Vis absorptions of perylene, Per-
CuC–C4H9, PerC6F4H, C6PerC6F4H, and their related com-
plexes 1–8 are closely related, and are dominated by the π–π*
transition of the perylene moiety. The absorption spectra
consist of two strong transitions, a broad very intense one in
the UV, at 240–315 nm, and a second one in the visible, at
350–475 nm, with a vibronic structure; for 1 the coordination
to Co2(CO)6 results in loss of the fine structure and significant
broadening of the spectrum, extending to approximately
700 nm. The vibronic structure, with a vibrational spacing
of ∼1300 cm−1, is related to the ν(CvC) frequency of the poly-
aromatic system.
The perturbation on the perylene spectrum observed in the
visible for the C6F4H group is quite similar (444 nm for C6F4H
versus 439 nm for perylene, that is ∼260 cm−1) and only mod-
erately different to that produced by the (C6F4)MLn fragments
(further 0–230 cm−1). This is in contrast with our previous
observations of larger effects for Pt(PEt3)2X groups (X = NCS,
CN, NO3, CNtBu, PyMe) σ-bonded directly to the perylene
core.5 Moreover, the absorptions for 1–8 show also a very small
solvent dependence. For example, when the solvent is changed
from toluene to acetonitrile, the lowest energy bands of 8 are
red-shifted only by less than 300 cm−1 (see Fig. S1 in ESI†).
This behaviour suggests that these bands are most probably
intraligand π–π* transitions rather than charge transfers. It
also supports the fact that the electronic connection of the per-
ylene and the metal fragments through the C6F4 link is very
weak, which is due to the large dihedral angle between the
perylene and the C6F4 rings observed in the X-ray structures.
and only one of them is represented in Fig. 1. These differ
mostly in the arrangement of the butyl chain with respect to
the perylene. The structure contains a tetrahedral Co2C2 unit
with the C(21)–C(22) bond essentially perpendicular to the
Co(1)–Co(2) bond. In addition, the alkyne unit C(21)–C(22) is
substituted with a perylenyl group at C(21) and a butyl group
at C(22), whereas the two cobalt atoms Co(1) and Co(2) are
each bound to three terminal carbonyls. The Co(1)–Co(2)
(2.459(2) Å) and C(21)–C(22) (1.337(10) Å) distances as well
as the C(1)–C(21)–C(22) (144.6(7)°) and C(21)–C(22)–C(23)
(140.6(7)°) angles are similar to those found for other tetra-
hedral Co2C2 systems.10,18
The perylenyl fragments in complexes 2a or 6a are essen-
tially planar (the dihedral angles between the two “naphthal-
ene” moieties forming the perylene are 2.69° (2a) and 3.69°
(6a)), and make dihedral angles to the tetrafluorophenyl plane
of 57.49° (2a) and 77.75° (6a). The C–C–C angles at the ipso
carbon of the C6F4 group in both complexes are less than 120°
(112.7(11)° and 113.2(4)° for 2a and 6a, respectively), because
of electronic effects of the electropositive metal and electro-
negative fluorine substituents at the ortho positions.19
The gold coordination in 2a is almost perfectly linear,
with C(1)–Au–C(27) bond angles of 178.1° and 179.4° for N(1)–
C(27)–Au. The bond lengths Au–C(1) (tetrafluorophenyl)
(1.999(12) Å) and Au–C(27) (isocyanide) are comparable to
related aryl-gold and isocyanide-gold complexes.20,21 The mole-
cular packing features the association of two monomers
(Fig. 2) arranged almost antiparallel, with an Au⋯Au distance
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Table 3 UV-Vis absorption, excitation and emission data for Per-CuC–C4H9, PerC6F4H, C6PerC6F4H and their complexes 1–8, in CHCl3 at 298 K, and half-wave redox
potentials in CH2Cl2
Compound
λ(nm) (10−3 ε)/dm3 mol−1 cm−1
λex/nm
λem/nm
Φa
τb/ns
E1ox
PerC6F4H
C6PerC6F4H
Per-CuC–Bu
1
2a
3a
3b
4a
4b
5a
6a
7a
8a
255 (39.6), 398 (12.5), 417 (27.8), 444 (33.5)
256 (46.9.2), 396 (12.3), 421 (30.3), 446 (37.0)
259 (48.1), 408 (15.3), 431 (31.4), 459 (38.9)
257 (32.8), 457 (17.3), 477sh (13.7), 596sh (2.4)
259 (77), 398 (13.3), 419 (29.4), 445 (37)
257 (80), 274 (72.7), 398 (15.6), 420 (33.6), 445 (42)
257 (56.4), 276 (35.1), 402 (18.1), 425 (35.5), 452 (44.2)
249 (74.6), 399 (18.3), 421 (37.2), 447 (45.6)
241 (67.1), 257 (64.2), 402 (16.5), 428 (35.6), 454 (43.8)
256 (66.3), 398 (14.7), 420 (30.6), 445 (37.9)
257 (50.9), 399 (15.0), 421 (25.0), 445 (30.6)
256 (56.2), 398 (19.5), 420 (31.0), 445 (38.3)
256 (48.7), 398 (15.5), 420 (32.8), 445 (40.8)
418, 443
423, 448
431, 458
432, 455
418, 443
418, 443
428, 452
420, 446
427, 454
419, 444
420, 446
419, 444
419, 445
460, 485
466
0.96
0.96
0.80
0.37
0.85
0.95
0.93
0.19
0.16
0.80
0.71
0.83
0.86
4.34 (1.027)
4.30 (1.077)
4.32 (1.120)
3.93 (1.030)
4.06 (1.027)
3.35 (1.050)
3.44 (1.016)
1.12
1.03
1.08d
1.08d
1.08
1.08
1.02
1.06
1.03
1.08
1.07
1.08
1.10
465, 496
465, 494
460, 487
461, 488
469, 496
461, 489
469, 497
460, 488
461, 488
461, 487
461, 488
0.25 [49.3], 2.18 [50.7] (1.034)c
0.41 [48.4], 2.42 [51.6] (1.044)c
3.48 (1.017)
2.09 (1.024)
3.59 (1.011)
3.63 (1.020)
a Quantum yield. b Fluorescence lifetimes in dichloromethane; numbers in parentheses indicate the χ2 values of the fits obtained by
deconvolution. c Decays were bi-exponential; numbers in brackets indicate the relative amplitude of components. d Irreversible oxidation
peak.
Molecular orbital calculations
phase, the first contribution (internal MO → LUMO) is more
important than the second, but in solution the opposite holds.
DFT calculations were performed on representative PerC6F4Y For simplicity only, the HOMO → π*(Per) transition is depicted
compounds in order to better understand their absorption in Fig. 4.
spectra. The selected molecular species were PerC6F4H,
The spectra of the complexes containing the (PerC6F4)Au-
PerC6F5, (PerC6F4)Au(CNMe), (PerC6F4)PdBr(PMe3)2 and (CNMe), (PerC6F4)PdBr(PMe3)2 and (PerC6F4)PtBr(PMe3)2 frag-
(PerC6F4)PtBr(PMe3)2. Their optimized theoretical structures ments were also calculated. The transitions and orbitals
are available in the ESI.† The main calculated geometric para- involved are shown in Fig. 4 for (PerC6F4)AuCNMe, and
meters match the experimental observations. For example, are given in the ESI† for (PerC6F4)PdBr(PMe3)2 and (PerC6F4)
the naphthalene moieties are practically coplanar having only PtBr(PMe3)2. In the three complexes the lower energy bands
small dihedral angles between the naphthalene halves: ca. 1° correspond to the HOMO → LUMO transition and are
for the organic molecules, 2° for Au, and 3° in the Pd and Pt calculated to appear at 448 nm (Au) and 443 nm (Pd and Pt) in
derivatives. The tetrafluorophenyl and perylene planes are the gas phase, and 457 nm (Au), 456 nm (Pd) and 457 nm (Pt)
staggered, with dihedral angles of 60° in the organic molecules in CHCl3. This is in satisfactory concordance with the experi-
and 62° in their metal complexes. The dihedral angles of pery- mental values of 445 nm (2a), 445 nm (5a), and 445 nm (7a).
lene with the square-planar coordination planes of Pd and Since the involved orbitals are centered in the perylene frag-
Pt come close to coplanarity (8° for Pd and 7° for Pt). Finally, ment, the wavelength values associated with these absorptions
C–H⋯F–C contacts are present in all the calculated structures are very similar to that found for PerC6F4H. The calculations
with 2.6–2.86 Å distances, within the range of experimental predict an increased intensity (ca. 20%), compared to the free
data.24
ligand, for the bands in the complexes. This is also in agree-
The absorption spectra were calculated by TD-DFT, in the ment with the experiment (experimental values: ε = 33 for the
gas phase and in CHCl3. In the organic compound PerC6F4H free ligand versus ε = 37 for complexes).
(Table 4) two bands at 442 and 256 nm are predicted, as
The calculations for the Au complex predict, in addition,
observed. The first peak is the most intense one (f ≈ 0.49), and absorptions in the ranges 293–288 and 254–231 nm. According
it corresponds to a HOMO → LUMO transition. These orbitals to the analysis of the orbitals, the peak at 293 nm is assigned
can be described as the antisymmetric and symmetric combi- to a transition from π to π* orbitals of the perylene (Fig. 4) and
nations of π* orbitals of two naphthalene moieties of the pery- is related to those observed for PerC6F4H at ca. 256 nm. The
lene, respectively. Since these orbitals are essentially centered shift observed is due to the electron withdrawing effect of the
in the perylene fragment without any significant contribution C6F4 group. However, when a solvent effect is introduced, this
of the fluoroaryl ring, this energy gap (0.11 au ≈ 3 eV) is contribution decreases in the low-intensity band at 291 nm,
almost the same for the metal complexes. A second band, at increasing the intensity in a band at 260 nm (which is centered
∼256 nm, has lower intensity than the former, and is assigned in a transfer from the perylene π system to the tetrafluoro-
to a combination of several transitions between π orbitals of phenyl ring and the isocyanide ligand in the gas phase). The
the perylene. The major contributions are transitions between peak at 288 nm is clearly assigned to a charge transfer from
the lower occupied MO and the LUMO and between the the tetrafluorophenyl ring to the isocyanide ligand, in concor-
HOMO and a higher empty MO (π*(Per) in Fig. 4). In the gas dance with our calculation for the complex (C6F5)Au(CNMe)
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Table 4 Calculated absorption wavelengths (in nm) and intensities (in par-
enthesis) for PerC6F4H and (PerC6F4)Au(CNMe), in gas phase and in CHCl3
PerC6F4H
(PerC6F4)Au(CNMe)
Gas phase CHCl3
Assignment
Gas phase CHCl3
Perylene:
HOMO → LUMO
Perylene: π → π*
442 (0.49) 455 (0.62) 448 (0.59) 457 (0.72)
257 (0.13) 259 (0.36) 293 (0.11) 291 (0.03)
255 (0.15) 257 (0.09)
260 (0.33)
288 (0.18) 266 (0.46)
254 (0.08) 239 (0.06)
252 (0.08) 255 (0.06)
231 (0.22) 227 (0.18)
LLCT: C6F4 → CNMe
LLCT: Perylene → CNR
LLCT: Perylene → C6F4
LLCT:C6F4 → Perylene
fragment (443 and 256 nm in the gas phase and 456 and 259
in CHCl3, respectively) do not change significantly. The elec-
tronic structure and orbital analysis of both complexes are dis-
cussed in the ESI.†
It is worth noting that the TD-DFT calculations show clearly
that the frontier orbitals of the C6F4 group do not interact with
the frontier orbitals of the perylene ligands. Consequently the
M orbitals cannot interact, even indirectly, with the perylene
orbitals through the C6F4 group and all the transitions occur
between singlet states.25 This is confirmed by the photophysi-
cal properties discussed below.
(b) Luminescence spectra. The luminescence spectra of
PerC6F4, PerCuC–Bu, C6PerC6F4 and their related complexes
1–8 at room temperature in chloroform are listed in Table 3.
All complexes exhibit strong luminescence in solution and
display emission bands with a well-defined vibronic structure
in the range 450–550 nm (see Fig. 4), which can be correlated
to those for perylene at about 425–525 nm. The similarity of
the overall luminescence spectra of these complexes with the
perylene strongly suggests a ligand-dominated emissive state
that can be assigned as intraligand π–π* disturbed by the sub-
stituents. On the basis of the similar Stokes shifts between
absorption and emission (less than 1000 cm−1 in all cases) the
luminescence observed can be assigned to π–π* fluorescence,26
which was supported by the fact that the emission properties
Fig. 3 Absorption spectra, recorded in CHCl3 solution (∼10−5 M) at room
temperature, for perylene, Per-CuC–C4H9, PerC6F4H, C6PerC6F4H and their com-
plexes 1–8.
(287 nm). According to calculations this LLCT is very sensitive remaining unchanged in the presence of air would be consist-
to solvent effect in both complexes and is calculated to be blue ent with this assignment.27 This was further confirmed
shifted to 266 and 262 nm, respectively, with increasing inten- with the measurement of their emission lifetimes, in the
sity. Analogously, the peak at 254 nm is assigned to a charge range 0.2–4.4 ns (Table 3). The emission lifetimes obtained
transfer from the perylene π system to the isocyanide ligand, for the complexes are similar. Usually, these ligands and
and calculations predict a red shift in CHCl3 to 239 nm. Conse- complexes show mono-exponential decay with lower life-
quently, these two absorptions should converge in the similar times for the metal derivatives. In contrast, 4a,b show bi-expo-
region with larger intensity in solution, and can be observed nential decay with two approximately equal components,
in 3a–b, although only a shoulder can be appreciated in 2a. one of about 0.3 ns and another substantially longer of about
Finally, interligand transfer bands from the perylene π system 2.2 ns.
to the isocyanide ligand are calculated at 254 nm (239 nm in
As shown in Fig. 5, the emission band in compound 1 rela-
solution), and interligand transfer bands from the tetrafluoro- tive to PerCuC–Bu (Fig. 5 above) did not show any shift,
phenyl ring to the perylene fragment are predicted to be below suggesting that the emission is fully perylene based, without
240 nm.
significant MLCT contribution by coordination to Co2(CO)6.
For (PerC6F4)PdBr(PMe3)2 and (PerC6F4)PtBr(PMe3)2 com- For the tetrafluorophenylperylene derivatives, Fig. 5 shows nor-
plexes, the two calculated bands related with the perylene malized emission spectra in chloroform solutions of 2–8.
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Fig. 4 Schematic representation of the main electronic transitions expected in the absorption spectra for PerC6F4H and (PerC6F4)AuCNMe.
Bands at λmax = 461 or 469 nm, for the tetrafluorophenyperyl- of perylene substituted organotrialkynyltin compounds where
enyl complexes without or with an alkyl chain attached to pery- an alkyl chain connects the perylene core with a trialkynyl-
lene, respectively, are observed, with a vibronic structure stannyl group, thus insulating the fluorophore from the
similar to that observed for the perylene parent but less well metal;28 or the case of perylene bisimide metal complexes with
defined (Fig. 5 below). Comparison of the emission spectra of a 4-pyridine unit connecting the bisimide to a Pd(II) or Pt(II)
the metal complexes 2–8 with those found for the tetrafluoro- diphosphine complex;29 similar results have been reported for
phenyl ligands reveals that the MLn group does not exert sig- two palladium complexes of perylene diimides attached to the
nificant influence on the long-wavelength emission maxima.
bay region,25 which also show strong fluorescence (Φfl = 0.65
The effect of different solvents (acetonitrile, chloroform and and 0.22), or for perylenyl complexes containing a Pt(PEt3)2X
toluene) on the emission spectra of 8a was studied at room group (70–80% of the fluorescence of the mother organic
temperature (Fig. S2 in the ESI†). The nearly identical emission molecule).5 In contrast, for Pt(II) complexes ligated via an
spectra (<200 cm−1) indicate that the fluorescence of the per- acetylide bridge in the bay region to perylenediimide moieties,
fluorophenyl derivatives is hardly sensitive to the polarity of the fluorescence is totally quenched;30 the intense fluore-
the solvents.
scence of diazadibenzoperylene (Φfl = 0.80) is also strongly
quenched upon metal coordination.31
For the compounds reported here, the emission quantum
yields, Φfl, for PerC6F4H, C6PerC6F4H, and complexes 1–8,
measured in dichloromethane at room temperature were
Quantum yields
Although the presence of heavy atoms is usually detrimental
for quantum yields, there are a few literature reports of metal
complexes showing high fluorescence values. This is the case
determined using perylene in ethanol as standard (Φfl
=
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the positions and luminescence of the perylene bands in the
complexes can be used to trace the presence of these com-
plexes in different experimental conditions by luminescence
studies; (iv) the presence of the C6F4 link can be also used for
studies by 19F NMR, avoiding the interference of solvents that
1
occurs in H NMR studies. Metal complexes with luminescent
markers are of interest in a number of fields, for instance in
biological studies.33
The electrochemical properties of the compounds have
been measured in CH2Cl2 by cyclic voltammetry, in the range
+1.6 to −1.8 V, and are listed in Table 3. For the tetrafluoro-
phenyl derivatives 2a–8a only one reversible wave was found
within the range studied, at ca. +1.08 V, with a slightly
decrease in the potential of 0.04 V, relative to PerC6F4H,
(+1.12 V). The latter is very similar to perylene (+1.06 V).34 The
derivatives 3b and 4b (with an hexyl substituent on the pery-
lene core) are slightly easier to oxidize (+1.02 V), due to the
electron-donating nature of the alkyl substituent. The oxi-
dation of Per-CuC–Bu and complex 1 displays one irreversible
wave during the first cycle. Thus, the trends observed for the
redox processes and for the luminescence energies are roughly
coincident, as expected, confirming the insulation between the
π system of the perylenyl group and the metal fragments con-
nected to it through the C6F4 link.
Fig. 5 Emission spectra recorded in CHCl3 solution (∼10−5 M) at room temp-
erature, for Per-CuC–C4H9, PerC6F4H, C6PerC6F4H and their complexes 1–8.
Conclusions
Two tetrafluorophenylperylenes, PerC6F4H and C6PerC6F4H,
and several metallated complexes have been successfully pre-
pared. In most cases, attaching the heavy metal unit to the
fluorophore with C6F4 as a spacer does not significantly affect
the fluorescence properties of the perylene parents. Theoreti-
cal calculations of the absorption spectra of the PerC6F4–Y
compounds (Y = H, F, Au(CNMe), PtBr(PMe3)2 and PdBr-
(PMe3)2) support the fact that these are independent of the
substituent because the π systems of the perylene and tetra-
fluorophenyl fragments are uncoupled, according to the poor
coplanarity found in the molecular structure. Since these com-
plexes are highly luminescent and practically keep the optical
properties of perylene, they could be used as easily detected
markers.
0.92),32 with an excitation wavelength of 407 nm. The com-
plexes are highly fluorescent, with quantum yields in the range
0.16–0.95 (Table 3). A reduction in emission intensity for the
dicobalt complex 1 (Φfl = 0.37) is observed compared to the
uncomplexed perylenyl precursor PerCuC–Bu (Φfl = 0.80), but
this reduction is less than the decrease found in related
pyrenyl complexes (up to 95% decrease).9 Complexes 2–8
exhibit high Φfl values, all higher than 0.7 except for the
palladium complexes 4a and 4b that exhibit unexpectedly low
fluorescence quantum yield (Table 3).
A strong to good conservation of luminescence in our com-
plexes can be attributed to the very good insulation of the fron-
tier empty π*orbitals of the perylene fragment from the heavy
metal filled orbitals through the C6F4 connector group, which
makes a large dihedral angle to the perylene plane leading to
an efficient electronic decoupling of the metal fragment from
the HOMO and LUMO of the perylene chromophore. As
the presence of different metal centres (Au, Pd, Pt) in these
tetrafluorophenylperylenyl complexes has little effect on the
emission maxima and intensity relative to perylene, the intro-
duction of different substituents attached to the various auxili-
ary metal centers does not disturb the photophysical
properties of perylene. This makes the linking system an inter-
esting one for application, for a number of reasons: (i) it
makes strong bonds with late transition metals; (ii) the pres-
ence of ancillary ligands, and the link itself, help to increase
the solubility of the complexes; (iii) the high conservation of
Experimental section
Materials and general methods
All reactions were carried out under dry nitrogen. The solvents
were purified according to standard procedures. Literature
methods were used to prepare AuCl(tht),35 Pd2(dba)3,36
Pt(PEt3)4,37 1,2,3-tris(dodecyloxy)-5-isocyanobenzene,38 3-(1-
hexynyl)perylene,8 and 3-bromo-9(10)-hexylperylene.8 C, H, N
analyses were carried out on a Perkin-Elmer 2400 micro-
analyzer. IR spectra (cm−1) were recorded on a Perkin-Elmer
FT-1720X spectrometer. 1H and 31P NMR spectra were recorded
on a Bruker AC 300 or Bruker 400 MHz spectrophotometer in
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CDCl3, with chemical shifts referred to TMS and 85% H3PO4, hexafluorophosphate (0.1 M) in CH2Cl2 was used as a support-
respectively. UV-vis absorption spectra were obtained on a ing electrolyte and the solutions of the complexes were in the
Shimadzu UV-1603 spectrophotometer, in chloroform solution order 10−3 M. All scans were done at 100 mV s−1
(1 × 10−5 M). Luminescence data were recorded on a Perkin-
.
Computational details
Elmer LS-luminescence spectrometer, in CHCl3 (1 × 10−5 M).
Luminescence quantum yields were obtained at room temp- Unrestricted calculations were carried out using the
erature using the optically dilute method (A < 0.1) in degassed Gaussian09 package.40 The hybrid density function method
dichloromethane (quantum yields standard was perylene in B3LYP was applied.41 Effective core potentials (ECP) were used
ethanol, Фfl = 0.92,32 and using an excitation wavelength of to represent the innermost electrons of the transition atoms
407 nm in dichloromethane). The emission lifetime measure- (Au, Pt and Pd) and the basis set of valence double-z quality
ments were carried out with a Lifespec-red picosecond fluore- was associated with the pseudopotentials LANL2DZ.42 The
scence lifetime spectrometer from Edinburgh Instruments. basis set for the main group elements was 6-31G* (Br, P, C, N,
As excitation sources two diode lasers, with 405 and 470 nm F and H).43 Solvent effects of chloroform were taken into
nominal wavelengths, were used. The first wavelength account by PCM calculations,44 keeping the geometry opti-
(405 nm) has a pulse width of 88.5 picoseconds, and its typical mized for the gas phase (single-point calculations). Excited
average power is 0.40 mW. The second wavelength (470 nm) states and absorption spectra were obtained from the time-
has a pulse width of 97.2 picoseconds, and its typical average depending algorithm implemented in Gaussian09,45 using the
power is 0.15 mW. The pulse period is 1 μs and the pulse rep- B3LYP functional (a benchmark for the perylene molecule
etition frequency is 10 MHz. The monochromator slit is 2 nm. shows a more accurate wavelength than the PBE one, 445 and
The instrument response measured at the HWHM (half width 480 nm respectively).
at high maximum) was below 350 picoseconds. The technique
3-(2,3,5,6-Tetrafluorophenyl)perylene
(PerC6F4H). K2CO3
used is “Time Correlated Single Photon Counting” (TCSPC). (0.460 g, 3.33 mmol), PtBu2Me–HBF4 (75 mg, 0.30 mmol), Pd-
Mono-exponential and bi-exponential fluorescence decay (OAc)2 (34 mg, 0.15 mmol) and 3-bromoperylene (1.0 g,
models were fitted to each decay. Eqn (1) describes the mono- 3.02 mmol) were added in a Schlenk tube under N2 atmos-
exponential decay model:
phere. 1,2,4,5 Tetrafluorobenzene (1.01 mL, 9.05 mmol) and
DMA (20 mL) were then added via a syringe and the reaction
was heated to 120 °C for 15 h. The solvent was then evaporated
and the black residue purified by loading the crude reaction
mixture directly onto a silica gel packed flash chromatography
column using hexane–ethyl acetate (7 : 1) as an eluent (Rf =
0.4). Yield 0.670 g (56%). The product contains ca. 3% of
perylene (by H NMR integration). H NMR (300 MHz, CDCl3):
δ 8.3–8.23 (m, 4H), 7.65–7.28 (m, 2H), 7.56–7.46 (m, 4H),
7.38–7.35 (m, 1H), 7.21 (m, 1H). 19F NMR (CDCl3): δ −139.1
(m, 2Fortho), −140.3 (m, 2Fmeta). MS (m/z): 400.
3-Tetrafluorophenyl-9(10)hexylperylene (C6PerC6F4H). 3-Tetra-
fluorophenyl-9(10)hexylperylene was prepared similarly to
PerC6F4 using 3-bromo-9(10)-hexylperylene. Yield: 0.305 g
(35%). Rf (silicagel, hexane–ethyl acetate 7 : 1) = 0.5. Anal. calcd
for C32H24F4 (484.54): C, 79.32; H, 4.99. Found: C, 78.92; H,
4.76. 1H NMR (300 MHz, CDCl3): δ 8.28–8.14 (m, 4H),
7.65–7.11 (m, 1H), 7.56–7.46 (m, 4H), 7.37–7.34 (m, 1H),
7.25–7.16 (m, 1H). 19F NMR (CDCl3): δ −139.2 (m, 2Fortho),
−140.3 (m, 2Fmeta). MS (m/z): 484.
PerC6F4Br. To a solution of PerC6F4 (0.161 g, 0.402 mmol)
in dry THF (25 mL) was added dropwise a solution of n-BuLi in
hexane (0.27 mL, 1.6 M, 0.442 mmol) at −78 °C, under N2
atmosphere. After the solution was stirred at −60 °C for 2 h,
Br2 (0.1 mL, 12 mmol) was added at −78 °C and the reaction
IðtÞ ¼ I0expðꢀt=τÞ
ð1Þ
where I0 is the relative intensity, t is the time and τ is the
fluorescence lifetime, both expressed in ns. The bi-exponential
decay model is expressed by eqn (2) as
IðtÞ ¼ F1expðꢀt=τ1Þ þ F2expðꢀt=τ2Þ
ð2Þ
1
1
where F1 and F2 are the relative intensities associated with two
lifetimes, τ1 and τ2, respectively.
Mono-exponential models are normally used to fit fluore-
scence decay. Bi-exponential fits may be more appropriate for
samples containing non-linear decays. Fitting was done using
FAST software from Edinburgh Instruments by a least-squares
algorithm using a reconvolution approach. In this method,
convolution of eqn (1) or (2) with the instrumental response
function (IRF) is done prior to evaluating the goodness of fit
with a weighted χ2 parameter. The bi-exponential decay model
represents the data better than a single decay for samples 4a
and 4b as evidenced by the even distribution of the residuals
about zero. An extra parameter to the model, the ratio of F1 to
F2, is also given.
Electrochemical measurements
Electrochemical studies employed cyclic voltammetry using a mixture was slowly brought to room temperature (3 h). Then, a
potentiostat EG&G model 273. The three-electrode system was saturated aqueous solution of Na2S2O3 (7 mL) was added
equipped with a platinum (3 mm diameter) working electrode, and the mixture stirred for 0.5 h. The solvent was removed in
a saturated calomel reference electrode (SCE), and a Pt wire vacuum and the resulting orange residue was redissolved
counter electrode. The electro-chemical potentials were cali- in dichloromethane (20 mL), and the solution dried with
brated relative to SCE using ferrocene as an internal standard anhydrous MgSO4. Then, the solution was filtered through a
(Fc/Fc+) at +0.46
V
vs. SCE).39 Tetra-n-butylammonium Kieselguhr filter, and the solvent was evaporated to obtain an
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orange solid. The solid was washed with diethyl ether 1.12. Found: C, 66.20; H, 7.02; N, 1.18. 1H NMR (300 MHz,
(2 × 5 mL) and dried under vacuum. Yield: 0.180 g, 93% (con- CDCl3): δ 8.25 (m, 4H), 7.72 (m, 2H), 7.40–7.60 (m, 5H), 6.74
tains ca. 3% of perylene (by 1H NMR integration)). 1H NMR (s, 2H, CNC6H2), 4.0 (m, 6H, OCH2)3, 1.90–1.65 (m, 6H, OCH2–
(300 MHz, CDCl3): δ 8.3–8.24 (m, 4H), 7.65–7.28 (m, 2H), CH2), 1.54–1.15 (m, 54H, C9H18–CH3)3, 0.90 (t, 9H, CH3).
7.56–7.46 (m, 4H), 7.37–7.34 (m, 1H). 19F NMR (CDCl3): 19F NMR (CDCl3): δ −117.6 (m, 2Fortho), −141.6 (m, 2Fmeta). IR
δ −133.4 (m, 2Fortho), −138.4 (m, 2Fmeta). MS (m/z): 478.
(KBr, cm−1): 2213 ν(CuN). 3b: Yield, 110 mg (65%). Anal.
PerC6F4I and C6PerC6F4I. The method was the same as calcd for C75H100AuO3NF4: C, 67.40; H, 7.54; N, 1.05. Found:
above but used I2 instead of Br2. 3-(2,3,5,6-Tetrafluoro-4-iodo- C, 67.15; H, 7.40; N, 1.10. 1H NMR (300 MHz, CDCl3):
phenyl)perylene, yield: 0.780 g (94%) (the product contains δ 8.32–8.12 (m, 4H), 7.91 (d, J = 8.3 Hz, 1H), 7.59–7.42 (m, 4H),
ca. 5% of perylene (by 1H NMR integration)). 1H NMR 7.37 (d, J = 7.5, 1H), 6.75 (s, 2H, CNC6H2) 4.0 (m, 6H, OCH2),
(300 MHz, CDCl3): δ 8.30–8.24 (m, 4H), 7.65–7.28 (m, 2H), 3.03 (t, J = 7.5 Hz, 2H, Per–CH2), 1.90–1.65 (m, 6H, OCH2–
7.56–7.46 (m, 4H), 7.35 (m, 1H). 19F NMR (CDCl3): δ −120.61 CH2), 1.55–1.17 (m, 62H, (C9H18–CH3)3, and C4H8–CH3), 0.95
(m, 2Fortho), −137.9 (m, 2Fmeta). MS (m/z): 526.
(m, 12H, CH3). 19F NMR (CDCl3): δ −117.5 (m, 2Fortho), −141.6
3-(2,3,5,6-Tetrafluoro-4-iodophenyl)-9(10)hexylperylene, yield: (m, 2Fmeta). IR (KBr, cm−1): 2213 ν(CuN).
0.300 g (70%). 1H NMR (300 MHz, CDCl3): δ 8.30–8.24 (m, 4H),
trans-[PdR(PPh3)2I] (R = PerC6F4 (4a); R = C6-PerC6F4
7.65–7.28 (m, 2H), 7.56–7.46 (m, 4H), 7.36 (m, 1H). 19F NMR (4b)). To a solution of Pd2dba3 (0.140 g, 0.142 mmol) and
(CDCl3): δ −122.1 (m, 2Fortho), −139.2 (m, 2Fmeta).
PPh3 (0.150 g, 0.57 mmol) in toluene (12 mL) under N2 atmos-
[Co2(CO)6(μ–η2-C4H9CuC-Per)] (1). To a solution of 3-(1- phere was added PerC6F4I or C6PerC6F4I (0.285 mmol) and the
hexynyl)perylene (60 mg, 0.181 mmol) in 20 mL of dried mixture was stirred for 2 h at 50 °C. Then, the solvent was
dichloromethane (20 mL) was added Co2(CO)8 (64 mg, removed in vacuum and the residue was chromatographed on
0.187 mmol). The resulting solution was stirred for 3 h to deactivated alumina with CH2Cl2–hexane (1 : 1) as the eluent.
yield a dark green solution. The solution was filtered through 4a: Yield: 56%. Rf (CH2Cl2–hexano (1 : 1)): 0.62. Anal. calcd
a Kieselguhr filter, concentrated to ca. 10 mL and the dark for C62H41F4IP2Pd C, 64.35; H, 3.57. Found: C, 64.22; H, 3.79.
green solid 1 was precipitated by the addition of 30 mL of 1H NMR (300 MHz, CDCl3): δ 8.20 (m, 4H), 7.88–7.60 (m, 14H),
methanol. Yield: 55 mg (50%). Anal. calcd for C32H20Co2O6: C, 7.60–7.30 (m, 21H), 7.16 (d, J = 7.9 Hz, 1H), 6.98 (d, J = 8.8 Hz,
62.16; H, 3.26. Found: C, 62.05; H, 3.10. 1H NMR (400 MHz, 1H). 31P{1H} NMR (CDCl3): δ 22.6. 19F NMR (CDCl3): δ −118.9
CDCl3): δ 8.27–8.18 (m, 4H), 7.93 (d, J = 8.3 Hz, 1H), 7.79 (d, J = (m, 2Fortho), −141.9 (m, 2Fmeta). 4b: Yield: 0.140 g (56%). Rf
8.1 Hz, 1H), 7.73 (d, J = 8.3 Hz, 1H), 7.71 (d, J = 8.3 Hz, 1H), (CH2Cl2–hexane (1 : 1)): 0.5. Anal. calcd for C68H53F4IP2Pd: C,
7.60 (m, 1H), 7.50 (m, 2H), 3.33 (t, J = 8.1 Hz, 2H, CH2), 65.79; H, 4.30. Found: C, 65.50; H, 4.05. 1H NMR (300 MHz,
1.75–1.71 (m, 2H, CH2), 1.55–1.50 (m, 2H, CH2), 0.97 (t, J = CDCl3): δ 8.25–8.12 (m, 4H), 7.91 (d, J = 8.0 Hz, 1H), 7.82–7.65
7.1 Hz, CH3).
(m, 12H), 7.55 (m, 1H) 7.50–7.30 (m, 20H), 7.13 (d, J = 7.9 Hz,
[Au(PerC6F4)(CNtBu)] (2a). To a solution of PerC6F4 (63 mg, 1H), 6.98 (d, J = 8.8 Hz, 1H), 3.03 (t, J = 7.5 Hz, 2H, Per-CH2),
0.157 mmol) of dried THF (15 mL) was added a solution of 1.78 (m, 2H, Per-CH2–CH2–C4H9), 1.48 (m, 2H, Per-C2H4–
LiBu in hexane (0.108 mL, 1.6 M, 0.173 mmol) at −78 °C, C3H6–CH3), 1.37 (m, 4H), 0.91 (t, J = 7.5 Hz, 3H, CH3). 31P{1H}
under nitrogen. After the solution was stirred for 1 h at NMR (CDCl3): δ 22.6. 19F NMR (CDCl3): δ −119.1 (m, 2Fortho),
−60 °C, solid [ClAu(tht)] (50 mg, 0.157 mmol) was added at −141.9 (m, 2Fmeta).
−78 °C and the reaction mixture was slowly brought to room
trans-[PdR(PEt3)2I] (R = PerC6F4, (5a); R = C6-PerC6F4
temperature (2 h). Then, a few drops of water were added and (5b)). The method was the same as for 4a,b with Pd2dba3
after CNtBu (18 μL, 0.16 mmol) and the solution was stirred (0.061 g, 0.058 mmol), PEt3 (0.06 mL, 0.33 mmol) and
for 0.5 h. The solvent was then evaporated and the residue was PerC6F4I or C6PerC6F4I (0.11 mmol). Yield: 40 mg (42%). Rf
redissolved in CH2Cl2, and the solution dried with magnesium (CH2Cl2–hexane (1 : 2)): 0.62. Anal. calcd for C38H41F4IP2Pd: C,
sulfate. The solution was filtered through a silicagel filter, and 52.52; H, 4.76. Found: C, 52.22; H, 4.58. 1H NMR (300 MHz,
the solvent was then removed in vacuum. The solid was recrys- CDCl3): δ 8.33–8.16 (m, 4H), 7.78–7.65 (m, 1H), 7.55–7.46
tallized from CH2Cl2/diethyl ether affording a yellow precipi- (m, 4H), 7.38–7.36 (m, 1H), 1.9 (m, 12H, 6CH2CH3), 1.3–1.03
tate 2a, which was vacuum-dried. Yield: 67 mg (67%). Anal. (m, 18H, 6CH2CH3). 31P{1H} NMR (CDCl3): δ 16.5. 19F NMR
calcd for C31H20AuF4N: C, 54.80; H, 2.97; N, 2.06. Found: C, (CDCl3): δ −116.5 (m, 2Fortho), −141.5 (m, 2Fmeta). 5b: Yield:
1
54.62; H, 3.06; N, 2.13. H NMR (300 MHz, CDCl3): δ 8.25 (m, 53 mg (48%). Anal. calcd for C44H53F4IP2Pd: C, 55.44; H, 5.60.
4H), 7.73 (d, J = 8.31 Hz, J = 3.51 Hz, 2H), 7.55–7.44 (m, 5H), Found: C, 55.19; H, 5.38. 1H NMR (300 MHz, CDCl3):
1.65 (s, 9H, CNtBu). 19F NMR (CDCl3): δ −117.8 (m, 2Fortho), δ 8.33–8.15 (m, 5H), 7.94 (m, 1H), 7.54–7.43 (m, 4H), 7.38–7.30
−141.8 (m, 2Fmeta). IR (KBr, cm−1): 2226 ν(CuN).
(m, 2H), 3.05 (t, J = 7.5 Hz, 2H, Per-CH2), 1.88 (m, PCH2), 1.79
[AuRCN(C6H2)-3,4,5-(OC12H25)3] (R = PerC6F4 (3a), R = C6- (m, 2H, Per-CH2–CH2–C4H9), 1.49 (m, 2H, Per-C2H4–C3H6–
PerC6F4 (3b)). The method was the same as above but used CH3), 1.37 (m, 4H), 1.15 (m, PCH2CH3) 0.92 (t, J = 7.5 Hz, 3H,
1,2,3-tris(dodecyloxy)-5-isocyanobenzene instead of CNtBu and CH3). 31P{1H} NMR (CDCl3): δ 16.5. 19F NMR (CDCl3): δ −116.5
the product was chromatographed on deactivated alumina (m, 2Fortho), −141.5 (m, 2Fmeta).
with CH2Cl2–hexane (1 : 1) as the eluent. 3a: Yield 70 mg,
trans-[Pd(PerC6F4)(PPh3)2(NCS)]
(6a). KSCN
(9
mg,
(40%). Anal. calcd for C69H88AuF4O3N: C, 66.17; H, 7.08; N, 0.092 mmol) was added to the stirred solution of 5a (0.040 g,
Dalton Trans.
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0.046 mmol) in 10 mL of acetone under N2 atmosphere. After
12 h, the solvent was distilled off, and the residue was
redissolved in a minimal amount of dichloromethane, and the
cloudy solution was filtered through Kieselguhr. Complex 6a
was precipitated by the addition of hexane (30 mL) as a yellow
solid. Yield: 0.035 g, 70%. Anal. calcd for C63H41F4NP2PdS:
C, 69.52; H, 3.80; N, 1.29. Found: C, 69.13; H, 3.79, N, 1.26.
1H NMR (300 MHz, CDCl3): δ 8.22 (m, 4H), 7.77–7.60 (m,
14H), 7.57–7.39 (m, 21H), 7.13 (d, J = 7.9 Hz, 1H), 6.93 (d, J =
8.8 Hz, 1H). 31P{1H} NMR (CDCl3): δ 23.8. 19F NMR (CDCl3):
δ −118.3 (m, 2Fortho), −141.9 (m, 2Fmeta). IR (KBr, cm−1): 2081
ν(NvCvS).
Table 5 Crystal data and structure refinements for 1, 2a and 6a
Compound
1
2a
6a. CH2Cl2
Empirical formula C32H20Co2O6 C31H20AuF4N
C63H41F4NP2PdS
1173.29
298(2)
Formula weight
618.34
298(2)
679.45
298(2)
Temperature (K)
Wavelength (Å)
0.71073
Triclinic
P1
0.71073
Orthorhombic Triclinic
Pccn
7.685(3)
24.297(8)
30.344(10)
90
90
90
5666(3)
8
1.593
5.238
0.71073
Crystal system
Space group
a (Å)
b (Å)
c (Å)
ˉ
ˉ
P1
8.818(7)
14.019(11)
22.704(18)
78.851(16)
84.38(2)
89.824(19)
2740(4)
4
11.526(3)
12.499(4)
20.347(6)
78.327(6)
80.155(6)
70.918(6)
2695.5(14)
2
α (°)
β (°)
γ (°)
V (Å3)
Z
trans-[Pd(PerC6F4)(PEt3)2X] (X = Br (7a); X = I (8a)). To a
solution of Pt(PEt3)4 (0.190 g, 0.285 mmol) in toluene (20 mL)
under N2 atmosphere was added PerC6F4Br (for 7a) or
PerC6F4I (for 8a) (0.285 mmol) and the mixture was stirred for
12 h at room temperature. Then, the solvent was removed in
vacuum and the residue was chromatographed on deactivated
alumina with CH2Cl2–hexane (2 : 1) as the eluent. 7a: Yield:
0.060 g, (23%). Anal. calcd for C38H41F4BrP2Pt: C, 50.12;
Dcalc (g cm−3
)
1.499
1.255
1.446
0.598
Absorpt.
coefficient (mm−1
F(000)
)
1256
2624
1192
Crystal size (mm)
0.29 × 0.21 × 0.26 × 0.10 ×
0.02 0.09
0.92 to 23.56 1.34 to 26.66
0.28 × 0.23 ×
0.20
1.03 to 26.43
Theta range for
data collection
Reflections
collected
18 633
47 834
23 773
1
H, 4.54. Found: C, 49.62; H, 3.93. H NMR (300 MHz, CDCl3):
δ 8.26 (m, 4H), 7.73 (m, 2H), 7.60–7.43 (m, 5H), 7.40–7.32
(m, 1H), 1.85 (m, 12H, 6CH2CH3), 1.17 (m, 18H, 6CH2CH3).
31P{1H} NMR (CDCl3): δ 13.9 (s, JPPt = 2442 Hz). 19F NMR
Independent
reflections
Absorption
correction
7968
5939
11 010
Multi-scan
Multi-scan
Multi-scan
(CDCl3): δ −119.3 (m, 2Fortho, JFPt = 446 Hz), −142.7 (m, 2Fmeta
,
Max. and min.
transmission
factor
Data/restraints/
parameters
1.000 and
0.739836
1.000 and
0.596514
1.000 and
0.786607
JFPt 104 Hz). 8a: Yield: 0.075 g, (27%). Anal. calcd
=
for C38H41F4IP2Pt: C, 47.66; H, 4.31. Found: C, 47.40; H, 4.15.
1H NMR (300 MHz, CDCl3): δ 8.25 (m, 4H), 7.72 (m, 2H),
7.60–7.43 (m, 5H), 7.40–7.32 (m, 1H), 1.85 (m, 12H, 6CH2CH3),
7968/0/723
5939/0/336
1.075
11 010/0/676
1.028
Goodness-of-fit on 0.966
F2
1.16 (m, 18H, 6CH2CH3). 31P{1H} NMR (CDCl3): δ 33.0 (s, JPPt
=
R1 [I > 2σ(I)]
wR2 (all data)
0.0579
0.1735
0.0657
0.2173
0.0572
0.1733
2442 Hz). 19F NMR (CDCl3): δ −120.2(m, 2Fortho, JFPt = 426 Hz),
−143.1 (m, 2Fmeta, JFPt = 97 Hz).
X-ray crystal structure analysis
publications with the deposition numbers CCDC-870559 for 1,
CCDC-870560 for 2a, and CCDC-870561 for 6a. www.ccdc.cam.
Single crystals of 1, 2a and 6a suitable for X-ray diffraction
studies were obtained from slow diffusion of hexane into a
dichloromethane solution of the products at −20 °C. Crystals
were mounted in glass fibers, and diffraction measurements
were made using a Bruker SMART CCD diffractometer with
Mo-Kα radiation (λ = 0.71073 Å).46 Intensities were integrated
from several series of exposures, each exposure covering 0.3°
in ω, the total data set being a hemisphere.47 Absorption
corrections were applied, based on multiple and symmetry-
equivalent measurements.48 The structures were solved by
direct methods and refined by least squares on weighted F2
values for all reflections (see Table 5).49 All non-hydrogen
atoms were assigned anisotropic displacement parameters and
refined without positional constraints. All the hydrogen atoms,
including those involved in hydrogen bonding, were calculated
with a riding model. Complex neutral-atom scattering factors
were used.50 Several peaks of low intensity were found in the
structure of compound 2a which, despite repeated attempts,
could not be fitted to a chemically sensible model. Crystallo-
graphic data (excluding structure factors) for the structures
reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
Acknowledgements
We thank the Spanish Ministerio de Economía y Competitivi-
dad (CTQ2011-2513 and CTQ2011-23862-C02), the Junta de
Castilla y León (Project VA248A11-2), and the Generalitat de
Catalunya (grant 2009SGR-1459) for financial support. Com-
puting resources at the Centre de Supercomputació de Catalu-
nya (CESCA) were used through a grant of Fundació Catalana
per a la Recerca (FCR).
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