Highly fluorescent platinum(II) organometallic complexes of perylene and perylene monoimide, with Pt σ-bonded directly to the perylene core

Article abstract of DOI:10.1021/ic1003319

3-Bromoperylene (BrPer) or N-(2,5-di-tert-butylphenyl)-9-bromo-perylene-3, 4-dicarboximide (BrPMI) react with [Pt(PEt₃)₄] to yield trans-[PtR(PEt₃)₂Br] (R = Per, 1a; R = PMI, 1b). Neutral and cationic perylenyl complexes containing a Pt(PEt₃)X group have been prepared from 1a,b by substitution of the Br ligand by a variety of other ligands (NCS, CN, NO₃, CN^tBu, PyMe). The X-ray structures of trans-[PtR(PEt₃)₂X] (R =Per, X = NCS (2a);R =PMI, X= NO₃ (4b); R = Per, X = CN^tBu (5a)) show that the perylenyl fragment remains nearly planar and is arranged almost orthogonal to the coordination plane: The three molecules appear as individual entities in the solid state, with no π-π stacking of perylenyl rings. Each platinum complex exhibits fluorescence associated to the perylene or PMI fragments with emission quantum yields, in solution at room temperature, in the range 0.30-0.80 and emission lifetimes ～4 ns, but with significantly different emission maxima, by influence of the X ligands on Pt. The similarity of the overall luminescence spectra of these metalated complexes with the perylene or PMI strongly suggests a perylene-dominated intraligand π- π^*emissive state, metal-perturbed by interaction of the platinum fragment mostly via polarization of the Ar-Pt bond.

Full text of DOI:10.1021/ic1003319

Inorg. Chem. 2010, 49, 9169–9177 9169
DOI: 10.1021/ic1003319
Highly Fluorescent Platinum(II) Organometallic Complexes of Perylene and
Perylene Monoimide, with Pt σ-Bonded Directly to the Perylene Core
ꢀ
Sergio Lentijo, Jesus A. Miguel,* and Pablo Espinet*
´
ꢀ
IU CINQUIMA/Quımica Inorganica, Facultad de Ciencias, Universidad de Valladolid, 47071 Valladolid, Spain
Received February 18, 2010
3-Bromoperylene (BrPer) or N-(2,5-di-tert-butylphenyl)-9-bromo-perylene-3,4-dicarboximide (BrPMI) react with
[Pt(PEt3)4] to yield trans-[PtR(PEt3)2Br] (R = Per, 1a; R = PMI, 1b). Neutral and cationic perylenyl complexes
containing a Pt(PEt3)X group have been prepared from 1a,b by substitution of the Br ligand by a variety of other ligands
(NCS, CN, NO3, CNtBu, PyMe). The X-ray structures of trans-[PtR(PEt3)2X] (R = Per, X = NCS (2a); R = PMI, X = NO3
(4b); R = Per, X = CNtBu (5a)) show that the perylenyl fragment remains nearly planar and is arranged almost
orthogonal to the coordination plane: The three molecules appear as individual entities in the solid state, with no π-π
stacking of perylenyl rings. Each platinum complex exhibits fluorescence associated to the perylene or PMI fragments
with emission quantum yields, in solution at room temperature, in the range 0.30-0.80 and emission lifetimes ∼4 ns, but
with significantly different emission maxima, by influence of the X ligands on Pt. The similarity of the overall luminescence
spectra of these metalated complexes with the perylene or PMI strongly suggests a perylene-dominated intraligand
π-π*emissive state, metal-perturbed by interaction of the platinum fragment mostly via polarization of the Ar-Pt bond.
Introduction
liquid crystals with special spectral properties,13 as fluores-
cent labeling reagents, or as fluorescent chemosensors,14 and
recently, providing highly fluorescent J-aggregates.15
By far the majority of studies in this field elaborate around
the readily accessible perylene tetracarboximides, with notable
Perylene dyes are well-known since 1913 as highly photo-
stable pigments and dyes.1 In recent years there has been a
renewed interest in the design of new materials derived from
the perylene chromophore because of their exceptional che-
mical and photochemical stability,2 their high fluorescence
quantum yields (sometimes close to 100%),3 and the large
range of colors accessible by variation of the substitution pat-
tern on the perylene core through high yield synthetic routes.4
These materials have been used in photovoltaic cells,5 xero-
graphy,6 optical switches,7 organic electronic devices such as
organic light emitting diodes (OLED),8 laser dyes,9 or fluores-
cent collectors,10 as tracers in fluorescence analytical assays,11
for charge transport in Langmuir-Blodgett films,12 for
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*To whom correspondence should be addressed. E-mail: espinet@
qi.uva.es (P.E.).
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2010 American Chemical Society
Published on Web 09/22/2010
pubs.acs.org/IC

9170 Inorganic Chemistry, Vol. 49, No. 20, 2010
Lentijo et al.
€
€
contributions of Langhals’, Mullen’s, and Wurthner’s
research groups.16 The optical and photophysical properties
of the material are modified depending on the nature of the
organic substituents in the aromatic core. As a result of these
research efforts, many organic derivatives containing pery-
lene have been reported, including commercial products used
as dies for polymers that cover all the rainbow’s colors.
There are a few reports where the metal center is co-
ordinated to a ligand that contains the perylene core,17 or
π-bonded to the perylene core.18 Perylene-containing transi-
tion metal compounds with a direct σ-bond of the metal to
the aromatic perylene core have been little studied, probably
because attaching directly metal centers to aromatic cores of
Chart 1
organic chromopheres is usually very detrimental for fluo-
rescence (heavy-atom effect).19,20 Typically, the fluorescence
quantum yield of complexes with ligands attached to late
transition metals falls to values in the range 0-6% of those of
the free ligands. This fairly general rule holds also for perylene-
containing transition metal compounds of Pt or Pd.17a,b,21 Only
recently two complexes have been reported, with Pd bonded to
the bay region (1, 6, 7, and 12 position of perylene diimide unit)
of a perylene diimide,22 showing much higher quantum yields
(Φ = 0.65 and 0.22).
(16) A selection of recent articles: (a) Langhals, H.; Jaschke, H.; Bastani-
Oskoui, H.; Speckbacher, M. Eur. J. Org. Chem. 2005, 4313. (b) Langhals, H.
Helv. Chim. Acta 2005, 88, 1309. (c) Debije, M. G.; Chen, Z. J.; Neder, R. B.;
Watson, M. M.; Mullen, K.; Wurthner, F. J. Mater. Chem. 2005, 15(12), 1270.
(d) Nolde, F.; Qu, J.; Kohl, C.; Pschirer, N. G.; Reuther, E.; Mullen, K. Chem.;
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Rauscher, M. Chem.;Eur. J. 2006, 12, 4642. (g) Langhals, H.; Krotz, O. Angew.
Chem., Int. Ed. 2006, 45, 4444. (h) Avlasevich, Y.; Muller, S.; Erk, P.; Mullen, K.
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D.; Toele, P.; Jacob, J.; Mullen, K.; Hofkens, J.; Van der Auweraer, M.; De
Schryver, F. J. Am. Chem. Soc. 2007, 129(3), 610. (l) Kaiser, T. E.; Stepanenko,
V.; W€urthner, F. Angew. Chem., Int. Ed. 2007, 46, 5541. (m) Chen, Z.;
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Chem.;Eur. J. 2008, 14, 169. (o) Langhals, H.; Rauscher, M.; Strbe, J.; Kuck, D.
J. Org. Chem. 2008, 73, 1113. (p) Peneva, K.; Mihov, G.; Nolde, F.; Rocha, S.;
Hotta, J.; Braeckmans, K.; Hofkens, J.; Uji-i, H.; Herrmann, A.; Mullen, K.
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A problem in the study of perylene derivatives is the poor
solubility of the compounds. A strategy to alleviate the prob-
lem is to attach solubilizing side chains to the perylene, but
this approach is synthetically very demanding and usually
leads to mixtures of isomers.23 Our strategy to enhance the
solubility was to incorporate, at a side position of the perylene
core, a metal center with appropriate ligands. The presence of
the metal and their ancillary ligands should, additionally, offer
an easy way to modify the optoelectronic properties of the
material, and could offer an efficient tool to create new
structural and functional motifs, significantly widening the
diversity of photofunctional systems available. In the course of
this project and following the same idea, two complexes were
reported by the Rybtchinski group, with Pd directly attached
to the 1,7 aromatic positions of a perylene diimide (Chart 1).22
Here we report the synthesis of Pt(II) complexes with the
platinum σ-bonded to position 3 of the perylene core, obtained
by oxidative addition of either 3-bromoperylene (BrPer) or
N-(2,5-di-tert-butylphenyl)-9-bromo-perylene-3,4-dicarboximide
(BrPMI) to [Pt(PEt3)4], and by substitution of the Br ligand in
the products by a variety of other ligands (NCS, CN, NO3,
CNtBu, PyMe), affording neutral and cationic complexes. Our
initial source of perylene core was BrPMI, meant to provide
better solubility to the metal derivatives, but soon it was
realized that the presence of PEt3 was enough to induce good
solubility in the derivatives of unmodified BrPer (sometimes
the solubility is even higher for Per than for PMI derivatives).
This unexpected result offered an interesting simplification
for further studies, so some of the complexes were made only
with Per. The effects of combining the perylene core with
the electron density of metal center and the ancillary ligands
coordinated trans to the perylene are discussed.
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Article
Inorganic Chemistry, Vol. 49, No. 20, 2010 9171
Scheme 1
spectra of the derivatives with PMI show additionally the
.
expected ν(CdO) absorptions at about 1699 and 1656 cm-1
The compounds were isolated as brown or yellow solids
for the perylene complexes, and red or pink solids for the
PMI compounds. They are soluble in organic solvents
such as chloroform, dichloromethane, toluene, acetone,
and tetrahydrofuran (THF), but insoluble in hexane,
diethyl ether, methanol, and ethanol. The elemental
analyses, yields, relevant IR data, 1H and 31P{1H}NMR
data for the complexes are given in the Experimental
Section.
The 1H NMR spectra of the metal complexes are very
similar for each family. The aromatic resonances are
complex, because of the lack of symmetry of the com-
pounds, and were assigned with the help of COSY and
NOESY experiments. The 31P{1H} NMR spectra of all
the metal complexes are consistent with a trans arrange-
ment of the phosphines and show a sharp singlet with
195Pt satellites in the range 17.5-11.0 ppm. The 31P
chemical shifts are very similar for Per and PMI (a bit
smaller for the later), but quite sensitive to the fourth
ligand: ONO2 (17.24 ppm) < NCS (14.56) < CNtBu
(12.32) < Br (12.19)<Py-Me (11.74) < CN (11.16) for
the perylene complexes; ONO2 (17.02 ppm) < Br (12.12) <
CNtBu (11.75) for the PMI derivatives. The deshielding
is particularly marked for the nitrate complexes 4a,b.
Results and Discussion
Synthesis and Characterization. Following a literature
procedure, commercial perylene was brominated with
N-bromosuccinimide (NBS) in dimethylformamide (DMF)
to yield 3-bromoperylene (BrPer).24 N-(2,5-di-tert-butyl-
phenyl)-9-bromo-perylene-3,4-dicarboximide (BrPMI),
was obtained by bromination of PMI with bromine in
chlorobenzene.25 The syntheses of the platinum com-
plexes 1-6 are outlined in Scheme 1.
The complexes 1a,b were easily prepared in good yield,
as yellow solids, by oxidative addition of BrPer or BrPMI
to [Pt(PEt3)4] in toluene. Metathesis of 1a with one
molar equivalent of KSCN, in acetone, led to SCN for
Br exchange. The value 2099 cm-1 for ν(CN) suggests
N-coordination of the thiocyanato group,26 which was
confirmed by X-ray diffraction methods (see later).
Complexes 1a,b reacted with silver salts AgCN or AgNO3,
in acetone, yielding 3a or 4a,b respectively in good yield.
For the cyanide complex 3a, ν(CtN) is observed at
2116 cm-1. The facile displacement of the nitrate group
in compounds 4a,b by other ligands was used to obtain
cationic complexes.27 Thus, 5a,b and 6a were obtained in
high yield when 4a,b was treated with an equimolar amount
of tert-butylisocyanide or 4-methylpyridine, respectively,
and KPF6 was added to help for crystallization of the
cation complex with a larger anion. The IR spectra of 5a,b
show a ν(CtN) absorption (ca. 2195 cm-1) at wave-
numbers about 55 cm-1 higher than for the free isocyanide
as an effect of coordination to platinum(II).28 The IR
1
The JPtP values are in the range 2350-2850 Hz: ONO2
(2841 Hz) > NCS (2740) > Br (2704) > Py-Me (2662) >
CN (2590) > CNtBu (2413) for the perylene complexes;
ONO2 (2795 Hz) > Br (2666) > CNtBu (2382) for the
PMI derivatives. This range is typical of a trans-P-Pt-P
configuration about the platinum metal centers.29
Crystal Structures. X-ray quality crystals could be
obtained for the complexes 2a, 4b, and 5a. Their struc-
tures were determined by single-crystal X-ray diffraction
methods and are shown in Figure 1. Selected bond lengths
and angles are given in Table 1. Data collection and
refinement parameters are listed in the Experimental
Section.
In general, there are no significant changes in bond
lengths and angles of the perylene skeleton compared to
the X-ray structure reported for perylene.30 The Pt(II)
center shows, in all complexes, a slightly distorted square
planar geometry. Confirming the NMR studies, the
crystal structures of 2a, 4b, and 5a show that the triethyl-
phosphine ligands are in trans configuration, with P(1)-
Pt-P(2) angles in the range 174-178°. The Per or PMI
fragment is nearly planar and is arranged almost ortho-
gonal to the coordination plane (the dihedral angles are
89.72° (2a), 84.65° (4b), 84.62° (5a)). In 4b the imide group
and the N-aryl with the 2,5-di-tert-butyl groups are planar
and orthogonal to each other (dihedral angle 87.48°). The
plane of the NO3 ligand is also roughly perpendicular to
the coordination plane (89.16°). The Pt(1)-C(1) distances
are in concordance with the trans-influence of L: CNtBu
(5a, 2.057(6) A) > NCS (2a, 2.003(4) A) > ONO2 (4b,
1.995(14) A). The Pt-P (2.2979(14)-2.3264(19) A) bond
lengths are within normal ranges.
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Inorg. Chem. 2005, 44, 7886. (b) Kryschenko, Y. K.; Seidel, S. R.; Arif, A. M.;
Stang, P. J. J. Am. Chem. Soc. 2003, 125, 5193.
(30) Nther, C.; Bock, H.; Havlas, Z.; Hauck, T. Organometallics. 1998, 17,
4707.
ꢀ
ꢀ
Fernandez-Mayordomo, C.; Martín-Alvarez, J. M.; Levelut, A. M. Chem. Mater.
1998, 10, 3666. (d) Díez, A.; Fornies, J.; Fuertes, S.; Lalinde, E.; Larraz, C.;
Lopez, J. A.; Martín, A.; Moreno, M. T.; Sicilia, V. Organometallics. 2009, 28,
ꢀ
ꢀ
1705.

9172 Inorganic Chemistry, Vol. 49, No. 20, 2010
Lentijo et al.
Table 1. Selected Interatomic Distances (A) and Angles (deg) for the Complexes
2a, 4b, and 5a
2a
4b
5a CH2Cl2
3
Pt(1)-C(1)
1.995(14) 2.003(4)
2.314(3)
2.319(3)
2.057(11) 2.151(3)
1.130(16)
1.630(16)
2.057(6)
2.3080(14) 2.3264(19)
2.2979(14) 2.3189(19)
Pt(1)-P(1)
Pt(1)-P(2)
Pt(1)-N(1)
N(1)-C(21)
C(21)-S(1)
Pt(1)-C(61)
1.983(6)
1.131(7)
1.471(8)
C(61)-N(1)
N(1)-C(62)
O(1)-N(1)
1.263(6)
C(1)-Pt(1)-X
C(1)-Pt(1)-P(1)
X-Pt(1)-P(1)
C(1)-Pt(1)-P(2)
X-Pt(1)-P(2)
P(1)-Pt(1)-P(2)
N(1)-C(21)-S(1)
C(21)-N(1)-Pt(1)
C(61)-N(1)-C(62)
N(1)-C(61)-Pt(1)
177.1(5)
89.4(3)
88.6(3)
90.4(3)
91.4(3)
178.36(16) 177.5(2)
91.86(14) 90.55(16)
86.69(11) 91.93(18)
92.66(14) 87.53(16)
88.84(11) 89.98(18)
174.71(13) 174.33(5) 177.62(6)
177.5(19)
173.1(13)
175.9(7)
175.6(6)
perylene plane/coord. plane angle 89.72
84.65
84.62
organic compounds with extended aromatic cores, is
hindered here by the bulky PEt3 ligands, and the N-aryl
with two 2,5-di-tert-butyl groups in 4b. In effect, all the
molecules appear as basically individual objects with no
π-π stacking of perylenyl rings. Notwithstanding that,
some intermolecular contacts (O3-C21 (3.005 A) and
O4-H51A (2.457 A) distances are smaller than the sum of
the van der Waals radii) have been detected in 4b.
Photophysical Studies
(a). UV-vis Absorption Spectra. The UV-vis absorp-
tion and fluorescence behavior of the complexes has been
investigated in solution and in the solid state to study the
influence of the PtX(PEt3)2 group on the photophysical
properties of the Per or PMI. The platinum complexes are
fairly stable in solution but very slowly decompose with
change of the color of the solution after several days. The
decomposition is very slow, and the UV-vis spectrum of
1a in chloroform remains constant after 24 h.
The absorption spectra of perylene, BrPer, PMI, BrPMI,
and their corresponding platinum(II) complexes are shown
in Figure 2. The quantitative data are summarized in Table 2.
The UV-vis absorptions of perylene, BrPer, and their
related complexes 1a-6a display very similar profiles,
exhibiting absorptions dominated by the π-π* transition of
the perylene moiety. The spectra consist of a strong absorp-
tion at about 250 nm, with a more or less defined shoulder,
and three other broad overlapped absorptions in the range
370-500 nm. These lowest energy bands of BrPer and
1a-6a have similar band shapes that resemble the spectrum
of perylene (with very intense vibronic bands at 360-
460 nm) with a moderate red-shifted of 360-1400 cm-1
relative to perylene. Moreover, the lowest energy bands of
1a are fairly insensitive to solvent polarity, as they are red-
shifted less than 200 cm-1 when the solvent is changed from
toluene to DMF (see the Supporting Information, Figure S1).
The shift to higher wavelength (red shift for short)
observed in the complexes, relative to perylene indicates
that the perturbation exerted on the perylene by the Pt(PEt3)2X
groups is stronger (in the range 850-1410 cm-1) than that
of Br (360 cm-1), as observed also in related pyrenyl
Figure 1. ORTEPs of the crystal structures of the molecule (2a, 4b) or
the cation (5a) of compounds 2a, 4b, and 5a. The ellipsoids are shown at
30% probability (H atoms are omitted for clarity). The ellipsoids of the
minor component of the disordered structure of 2a and 5a have been
omitted for clarity. For 5a, the anion PF6 and co-crystallized CH2Cl2
have been omitted.
-
Complex 2a features N-bonded thiocyanate, with the
Pt-N(1)-C(21) and N(1)-C(21)-S(1) bond angles only
slightly deviated from linearity (173.1(13) and 177.5(19),
respectively). Reflecting the high trans-influence of the
perylenyl group, the Pt-N distance (2.052(12) A is longer
than those found in most thiocyanato-platinum(II) com-
plexes,31 but comparable to that found in the few related
trans R-Pt-NCS complexes reported.32 The Pt-O dis-
tances in 4b are not significantly different (ca. 2.15-2.17 A)
and are similar to those found in related complexes.27,29 In
5a, the Pt-C(61) distance (1.983(6) A) is within the range of
those reported for other tert-butylisocyanide platinum com-
plexes, with aryls in trans position.33
The crystal networks of the complexes show that the
potential aggregation of the molecules, often found in
(31) (a) Kishi, S.; Kato, M. Inorg. Chem. 2003, 42, 8728. (b) Johanson,
M. H.; Otto, S.; Oskarsson, A. Acta Crystallogr., Sect B. Sci. 2002, 58, 244.
(32) (a) Otto, S.; Roodt, A. Acta Crystallogr., Sect E. Struct. Rep. Online
2005, 61, 1545. (b) Behrens, U.; Hoffmann, K.; Kopf, J.; Moritz, J. J. Organomet.
Chem. 1976, 117, 91.
(33) See for example: (a) Ackermann, M. N.; Ajmera, R. K.; Barnes,
H. E.; Gallucci, J. C.; Wojcicki, A. Organometallics. 1999, 18, 787. (b) Huh,
H. S.; Lee, Y. K.; Lee, S. W. J. Mol. Struct. 2006, 789, 209. (c) Kim, Y. J.; Choi,
E. H.; Lee, S. W. Organometallics. 2003, 22, 3316.

Article
Inorganic Chemistry, Vol. 49, No. 20, 2010 9173
Table 3. Emission and Excitation in Chloroform Solution (10-5 M) and in the
Solid State (KBr pellet) at 298 K
CHCl3
CH2Cl2
KBr
λem
λex
/
/
compound
λex/nm
λem/nm
Φa
τ/ns nm
nm
BrPer
1a
2a
3a
4a
5a
6a
BrPMI
1b
4b
435
442
464
462
468
450
455
512
445, 468, 504sh
485, 516, 558sh 0.70
482, 511, 555sh 0.78
480, 510, 545sh 0.70
488, 517, 556sh 0.77
467, 496, 531sh 0.43
472, 501, 539sh 0.67
542, 577, 634sh 0.98b
4.65 470
4.48 480
5.02 460
4.26 480
1.88 474
4.19 450
553
553
547
547
545
534
561, 602 618, 660
542 618, 660
517, 540 581, 620
0.30c 4.46 457
0.34c 4.62 457
0.78c 4.65 462
685
669
654
5b
a Determined relative to perylene in ethanol (Φfl = 0.92)34 and using
an excitation wavelength of 409 nm in CH2Cl2). b Taken from the
literature.35 c Determined using Rhodamine B in ethanol (Φfl=0.70)36
and using an excitation wavelength of 510 nm in CH2Cl2).
is engaged in more extensive conjugation. While the pertur-
bation produced by the Br atom of the PMI lowest energy
band is very small, the Pt(PEt3)2X group produces a clear
red-shift of the visible bands ranging from 980 cm-1 for the
cationic complex 5b (X = CNtBu) to 1990 cm-1 for the
neutral compounds 1b (X = Br) and 4b (X = ONO2) (See
Figure 2), with bigger bathochromic shifts than perylenyl
complexes. This red shift is somewhat larger than in the case
of the perylene derivatives.
Figure 2. (top) Absorption spectra of perylene, BrPer and their plati-
num complexes 1a-6a, recorded in CHCl3 solution (∼10-5 M) at room
temperature. (bottom) Absorption spectra of PMI, BrPMI, and their
platinum complexes 1b, 4b, and 5b in CHCl3 at room temperature.
(b). Luminescence Spectra. The luminescence spectro-
scopic properties of the ligands and the platinum com-
plexes at room temperature in chloroform or in the solid
state (KBr dispersion or pellets) are listed in Table 3. Both
neutral and cationic complexes exhibit strong fluores-
cence in solution and have well-defined vibronic fine
structure (See Figure 3).
Table 2. UV-vis Absorption of Perylene, BrPer, BrPMI, and Their Platinum
Complexes, in Chloroform at 298 K
compound
λ/nm (10-3 ε)/M-1 cm-1
perylene
BrPer
1a
2a
3a
439 (35.2) 412 (26.8), 391 (11.9), 254 (34.9)
446 (28.6), 419 (23.3), 397 (10.9), 257 (30.4)
468 (25.8), 441 (33.6), 419 (21.5), 256 (36.1)
464 (28.4), 439 (26.3), 259 (33.3), 240 (28.6)
463 (31.7), 437 (29.1), 237 (38.7), 240 (24.9)
464 (28.8), 438 (26.0), 260 (27.0), 253 (26.5)
456 (38.0), 429 (30.9), 259 (51.0)
The platinum metal complexes display luminescent
properties, showing that the metal does not impose a
heavy atom effect. The similarity of the overall lumines-
cence spectra of these metalated complexes with the
perylene strongly suggests an intraligand π-π* transition
where the ligand orbitals have been slightly modified by
the presence of the metal. On the basis of the similar
Stokes shifts37 between absorption and emission for the
ligands and the complexes (lower than 1000 cm-1), the
luminescence observed can be assigned to π-π* fluores-
cence, which was supported by the fact that the emission
properties remain unchanged in the presence of air, and
confirmed with the measurement of their emission life-
times ∼4 ns, (see Table 2).
4a
5a
6a
459 (33.4), 432 (27.5), 260 (46.4)
512(33.6), 489 (35.3) 264 (32.8)
511 (32.6), 485 (32.5), 265 (33.0), 241 (16.2)
570 (36.2), 543 (38.8), 276 (53.6), 240 (50.0)
570 (34.3), 544 (36.7), 276 (59.3)
PMI
BrPMI
1b
4b
5b
539 (39.6), 515 (42.4), 270 (34.2), 242 (43.4)
complexes.21b The shift produced by cationic [Pt(PEt3)2X]þ
groups is lower than observed for neutral complex frag-
ments: 5aþ (850 cm-1)<6aþ (990 cm-1)<4a ∼ 2a ∼ 3a
(1180 cm-1)<1a (1410 cm-1). This is the expected result, as a
cationic charge in the platinum fragment should contract the
d orbitals of the platinum and reduce the magnitude of the
interaction with the perylene orbitals. Similar electronic
effects have been found in platinum-anthracenyl complexes
(see further discussion of these concepts in the last paragraph
of this paper preceding the conclusions).21a
For the perylene derivatives, Figure 3 shows normal-
ized emission spectra in chloroform solution of the com-
plexes 1a-6a. The cationic complexes 5a and 6a (λmax
470 nm) are less red-shifted relative to perylene than the
∼
neutral compound 1a-4a (λmax ∼ 485 nm), as expected
The PMI neutral derivatives 1b and 4b are deep purple,
with an intense purple fluorescence in solution. The cationic
complex 5b is red with a strong orange fluorescence in
solution. The electronic spectra 1b, 4b, and 5b show a profile
which differs from that of the perylene complexes (as PMI
differs also from Per) in the higher sharpness of the vibronic
structure for the PMI derivatives; it is frequent that the
vibrational structure is obscured when the aromatic residue
(34) Montalti, M.; Credi, A.; Prodi, L.; Gandolfini, M. T. Handbook of
Photochemistry, 3rd ed.; CRC Pres LLC: Boca Raton, FL, 2005.
(35) Baffreu, J.; Ordronneau, L.; Leroy-Lhez, S.; Hudhomme, P. J. Org.
Chem. 2008, 73, 6142.
ꢀ
ꢀ
(36) Lopez-Arbeloa, F.; Ruiz-Ojeda, P.; Lopez-Arbeloa, I. J. Lumin.
1989, 44, 105.
(37) (a) Lakowicz, J. R. Principles of Fluorescence Spectroscopy; Plenum
Press: New York, 1983. (b) Guilbault, G. G. Fluorescence, 2nd ed.; Marcel
Dekker, Inc.: New York, 1990.

9174 Inorganic Chemistry, Vol. 49, No. 20, 2010
Lentijo et al.
Table 4. Half-Wave Redox Potentials for Per and PMI Derivativesa
compd
E1ox
E1r
E2r
1a
2a
3a
4a
5a
6a
PMI
1b
4b
0.73
0.78
0.76
0.78
0.83
0.75
1.41
1.01
1.07
1.21
-1.01
-1.13
-1.13
-1.04
-1.49
-1.60
5b
a Rate: 0.1 V/s in CH2Cl2.
spectra in frozen chloroform show no additional emission
bands, and the shoulders are resolved as peaks.
The emission quantum yields, Φ, for 1a-6a and 1b, 4b,
and 5b measured in dichloromethane at room tempera-
ture are in the range 0.30-0.80 (Table 2), and show that
the perylenyl complexes of platinum are highly fluores-
cent, probably because of the weakness of the interaction
of the platinum filled π-orbitals with the frontier empty
π*-orbitals of the Per or PMI fragment (see below).
Similar results have been reported recently for two pal-
ladium complexes of perylene diimides, in that case
attached to the bay region, which also show strong
fluorescence (Φ = 0.65 and 0.22).22
Figure 3. Emission spectra recorded in CHCl3 solution (∼10-5 M) at
room temperature (top) Per and complexes 1a-6a. (bottom) PMI,
BrPMI, and complexes 1b, 4b and 5b.
The electrochemical properties of the Per and PMI
derivatives have been measured in CH2Cl2 by cyclic
voltammetry, in the range 1.6 to -1.8 V. Their voltam-
metric data are listed in Table 4. For Per complexes only
one reversible wave was found within the range studied, at
∼ þ0.75 V, with a decrease in the potential of at least
0.20 V, relative to perylene (þ1.06 V).40 As expected, the
PMI derivatives are easier to reduce because of the strong
electron-accepting nature of the carboximide substitu-
ents,41 and oxidation and reduction reversible waves were
observed. The neutral complexes 1b and 4b show one
oxidation in the range þ1.01 to þ1.07 V and one reduc-
tion at ∼ -1.18 V. For the cationic complex 5b the
oxidation potential is þ1.21 V, and the first reduction
potential is -1.10 V, but a second quasi-reversible reduc-
tion wave at -1.66 V is observed. Thus, compared to the
parent PMI ligand, oxidation and reduction potentials
appear at lower potentials, and this effect is less marked
for the cationic complex 5b than in the neutral derivatives
1b and 4b, suggesting that the Pt(PEt3)2X fragment
(which is not directly involved in the redox process) is
making the Per or PMI fragment more electron rich.17i
Although the two electronic processes are different, some
parallelism can be expected, at a qualitative level, between
the trends observed in a series of complexes for redox
processes and for luminescence energies, as seen here.
The effects of the substituents on the spectral shifts
deserves a final comment, as they can be correlated to
some basic features of the Pt-C bond, and to some
classical parameters. The Pt-C σ bond aryl is polarized
toward the carbon atom. On the other hand, the possible
π back-bonding component of this bond, involving the
π orbitals of Pt and the π* orbitals of the aryl, is expected
from the fact that the fluorescence spectrum should be a
mirror image of the absorption spectrum. At low tempera-
ture (77 K) in solution (whether in chloroform, 2-Me-THF
or toluene) the spectrum for 1a is almost identical to that of
the room temperature solution, but with the shoulders
resolved as a sharp peak (Supporting Information, Figure
S4). In the solid-state the intensity of emission bands
decreases noticeably, and the emission spectrum displays,
as expected, a broad maximum that is shifted to lower
energy (>2700 cm-1 for 1a) with respect to the solution
emissions.38 The nearly identical emission spectra of 1a in
different solvents, at room temperature (in Supporting
Information, Figure S5), indicates that the fluorescence of
the perylenyl derivatives is hardly sensitive to the polarity of
the solvent, consistent with the assignment of the emission.
For the PMI derivatives, both PMI and BrPMI exhibit
very similar emission spectra with λmax = 542 nm with a
vibronic structure similar to perylene but not as well-
defined (Figure 3 (bottom)). The complexes 1b, 4b, and 5b
also show strong luminescence and exhibit the character-
istic fluorescence of the PMI, but with significant low
energy shifts, bigger Stokes shifts, and less resolution of
the vibronic structure. Differently from the perylene com-
plexes (Figure 3 (top)), and similar to perylene diimides39
and BrPMI, the bands of 1b are somewhat sensitive to
solvent variation from toluene to acetonitrile (<600 cm-1
for PMI and <800 cm-1 for the complexes (Supporting
Information, Figure S4)). The emission maxima in com-
plexes 1b and 4b appear at 618 nm, 76 nm (2270 cm-1
)
red-shifted from PMI. In the cationic complex 5b, this red
shift is again lower than in the neutral derivatives, and its
emission maximum appears at 581 nm, shifted 39 nm,
1240 cm-1 (See Figure 3). At low temperature (77 K) the
(40) Parker, V. D. J. Am. Chem. Soc. 1976, 98, 98.
€
(41) Lee, S. K.; Zu, Y.; Herrmann, A.; Geerts, Y.; Mullen, K.; Bard, A. J.
(38) Yang, L.; Shi, M.; Wang, M.; Chen, H. Tetrahedron 2008, 64, 5404.
(39) Reisfeld, R.; Gvishi, R. Chem. Phys. Lett. 1993, 213, 338.
J. Am. Chem. Soc. 1999, 121, 3513.

Article
Inorganic Chemistry, Vol. 49, No. 20, 2010 9175
to be small for Pt (this effect has been observed in a related
Pd system22) because of the high stabilization of the d
orbitals at the end of the transition metal series.42 Thus,
the interaction of the fragments Pt(PEt3)2X with Per or
PMI through the C-Pt bond is transmitted mainly via a
σ interaction involving the 5dz orbital of Pt, with very
little π component. This does not mean that the phenom-
ena related from electron transitions involving π ligand
orbitals will not be indirectly affected, as the energy of all
the orbitals of the ligand will be slightly modified by the
polarization of the C-Pt bond, which in turn depends of
the ancillary ligands and the charge on platinum. This
destabilizing effect has been argued to be similar for the
highest occupied molecular orbital (HOMO) and the
lowest unoccupied molecular orbital (LUMO) of a poly-
cyclic aromatic system, implying that no shift should be
expected. However, a second consequence of the polar
interaction C-Pt is that, as calculated for pyrene,21b
an electron rich Pt 5dz orbital, being close but lower in
energy to the HOMO of the polycyclic aromatic system
will interact with it producing a reduction of the HOMO-
LUMO gap. In other words, it can be expected that 5dz
orbitals of Pt with enriched nucleophilicity (higher energy)
should produce higher red shifts for the polycyclic system
based transitions.
Should this conception be right, the observed trends in
this paper are expected to be related to other molecular
properties that depend on the donor ability of the ancillary
ligands and the charge on the Pt fragment. The adequate
classical concepts reporting on the energy of the correspond-
ing orbital involved in the Pt-C bond are the charge of the
complex, and the trans-effect of the ancillary ligands,43 which
has been determined on trans-[PtMeX(PEt3)2] and follows
the trend NO3<NCS<Br <CN, exactly in keeping with our
spectroscopic trends and with the C-Pt distances in com-
plexes 2a, 4b, and 5a, supporting our interpretation.44 Along
the same line, the series of nucleophilicity of ligands toward
platinum (nPt) shows the order Br < CN for neutral com-
plexes, and py < CNC6H11 for cationic complexes.45 Thus,
the spectroscopic effects observed are perfectly compatible
with the spectroscopic effects discussed above and support
that the observations can be understood without π back-
donation from Pt.
quantum yield is somewhat lower for the complexes than for
the precursor, but still in the same order of magnitude (many
of them in the range 70-80% of the mother molecule).
All the platinum complexes show a shift of the emission to
lower energy as compared to the free ligands. The formation
of platinum complexes with different X ligands in trans with
respect to the perylenyl ligand has a perfectly measurable and
distinct effect on the photophysical properties, although the
quantitative shift is moderate because the luminescence is
apparently localized on the perylene core and the platinum
d orbitals have a weak interaction with the π-system of the
perylenyl fragment. It seems that the spectroscopic effects of the
Pt fragment are originated mostly by variations in the energy of
the metal orbital involved in the C-Pt bond, induced by the
ancillary ligands and the charge of the platinum complex.
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 pre-
pare 3-bromoperylene,24 N-(2,5-di-tert-butylphenyl)-9-bromo-
perylene-3,4-dicarboximide,25 and [Pt(PEt3)4].46 C, H, N analyses
were carried out on a Perkin-Elmer 2400 microanalyzer. IR
spectra (cm-1) were recorded on a Perkin-Elmer FT-1720X
spectrometer. 1H and 31P NMR spectra were recorded on
Bruker AC 300 or Bruker 400 MHz spectrophotometers in
CDCl3, with chemical shifts referred to TMS and 85% H3PO4,
respectively. UV/vis absorption spectra were obtained on a
Shimadzu UV-1603 spectrophotometer, in chloroform solution
(1 ꢀ 10-5 M). Luminescence data were recorded on a Perkin-
Elmer LS-luminescence spectrometer, in CHCl3 (1 ꢀ 10-5 M)
and in solid state measurements were made using finely pulver-
ized KBr dispersions of the sample in 5 mm quartz tubes at room
temperature. Luminescence quantum yields were obtained at
room temperature using the optically dilute method (A < 0.1) in
degassed dichloromethane (quantum yields standards were
perylene in ethanol (Φfl = 0.92),47 and Rhodamine B in etanol
(Φfl = 0.70), using an excitation wavelength of 409 and 510 nm,
respectively, in dichloromethane).36 The emission lifetime mea-
surements were carried out with a Lifespec-red picosecond
fluorescence lifetime spectrometer from Edinburgh Instru-
ments. As excitation sources two diode lasers, with 405 and
470 nm nominal wavelengths, were used. The first wavelength
(405 nm) has a pulse width of 88.5 ps, with a typical average
power of 0.40 mW. The second wavelength (470 nm) has a pulse
width of 97.2 ps, and its typical average power is 0.15 mW.
The pulse period is 1 μs, and the pulse repetition frequency is
10 MHz. The monocromator slit is 2 nm. The instrument
response measure at the HWHM (half width at half maximum)
was below 350 ps. The technique used is “Time Correlated Single
Photon Counting” (TCSPC).
Conclusions
The first perylene and PMI derivatives of platinum were
synthesizedby attaching a Pt(PEt3)2X fragment (X = neutral
or anionic ligand) to the perylene or PMI molecule. The com-
pounds are soluble in common organic solvents. The metal
center is σ-bonded directly to the 3 position of the perylene
core. The coordination of Pt to perylene or PMI has a mode-
rate quenching effect on the fluorescence, but the organo-
platinum complexes are still highly fluorescent: the emission
Electrochemical Measurements. Electrochemical studies em-
ployed cyclic voltametry using a potentiostat EG&G model 273.
The three-electrode system was equipped with a platinum (3 mm
diameter) working electrode, a saturated calomel reference
electrode (SCE), and a Pt wire counter electrode. The electro-
chemical potentials were calibrated relative to SCE, using
ferrocene as an internal standard (Fc/Fcþ) at þ0.46 V vs SCE).
Tetra-n-butylammonium hexafluorophosphate (0.1 M) in
CH2Cl2 was used as supporting electrolyte, and the solutions
of the complexes were in the order 10-3 M.
(42) Anderson, G. K. In Comprehensive Organometallic Chemistry II;
Abel, E. W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon: Oxford, U.K., 1995;
Vol. 9, p 445.
(43) This series is based on the observed ν(Pt-C) frequencies in the IR:
Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev. 1973, 10,
335.
Synthesis of 1a. To a solution of [Pt(PEt3)4] (0.600 g, 0.90 mmol)
in 70 mL of toluene under N2 atmosphere was added 3-bromo-
perylene (0.300 g, 0.90 mmol). The green solution was stirred
(44) For 2a and 4b the distances are equal within experimental error.
(45) Tobe, M. L. In Comprehensive Coordination Chemistry; Wilkinson,
G., Gillard, R. D., McCleverty, J. A., Eds.; Pergamon Press: Oxford, 1987; Vol. 1,
p 313.
(46) Schunn, R. A. Inorg. Chem. 1976, 15, 208.
(47) Montalti, M.; Credi, A.; Prodi, L.; Gandolfini, M. T. Handbook of
Photochemistry, 3rd ed.; CRC Pres LLC: Boca Raton, FL, 2005.

9176 Inorganic Chemistry, Vol. 49, No. 20, 2010
Lentijo et al.
12 h, then the solvent was removed in vacuum. The brown
residue was washed with pentane (15 mL) and was recrystallized
from dichloromethane/methanol. The brown precipitate 1a was
dried in vacuum. Yield: 0.600 g, 87%. Anal. Calcd for C32H41-
BrP2Pt: C, 50.40; H, 5.42. Found: C, 50.04; H, 5.26. 1H NMR
(400 MHz, CDCl3): δ 8.58 (d, J = 7.6 Hz, H4), 8.16 (d, J =
7.3 Hz, H7), 8.13 (d, J = 8.8 Hz, H12), 8.11 (d, J = 7.8 Hz, H6),
7.80 (d, J = 7.8 Hz, H1), 7.63 (d, J = 8.8 Hz, H9), 7.61 (d, J = 8.1
Hz, H2), 7.59 (t, J = 8.1 Hz, H11), 7.42 (t, J = 7.8 Hz, H8), 7.41
(d, H10), 7.38 (t, J = 7.6 Hz, H5), 1.75-1.59 (m, 12H, CH2CH3),
1.09-0.98 (m, 18H, CH2CH3). 31P{1H} NMR (CDCl3): δ 12.19
(s, JPPt = 2704 Hz). UV/vis (CHCl3) λmax (ε, M-1 cm-1) = 468
(25840), 441 (33590), 418 (21510), 256 (36120). Fluorescence
emission (CHCl3, λexc = 442 nm) λem (Irel) = 471(1) nm,
515(0.55) nm.
was filtered and washed with H2O (2 ꢀ 3 mL). The solid was
redissolved in dichloromethane (20 mL), and the solution dried
with magnesium sulfate. The solution was filtered, and the
solvent was then removed in vacuum, yielding 5a as a yellow
solid. Yield: 0.085 g, 86%. Anal. Calcd for C37H50NF6P3Pt: C,
1
48.79; H, 5.53; N, 1.54. Found: C, 48.74; H, 5.37; N, 1.46. H
NMR (400 MHz, acetone-d6): δ 8.34 (d, J = 7.4 Hz, H9), 8.30 (d,
J = 8.3 Hz, H8), 8.27 (d, J = 9.0 Hz, H3), 8.16 (d, J = 8.2 Hz,
H11), 8.13 (d, J = 7.7 Hz, H2), 7.75 (d, J = 8.1 Hz, H6), 7.72 (d,
J = 8.3 Hz, H5), 7.54 (d, J = 7.6 Hz, H1), 7.51 (t, J = 7.9 Hz,
H7), 7.50 (t, J = 8.0 Hz, H10), 7.48 (t, J = 7.9 Hz, H4), 1.8-1.6
(m, 21H, CH2CH3, CNtBu), 1.13-1.05 (m, 18H, CH2CH3).
31P{1H} NMR (CHCl3): δ 12.32 (s, JPPt = 2413 Hz), -143.73
(septuplet, JPF = 713 Hz). IR (KBr, cm-1): ν 2196 (CtN). UV/
vis (CHCl3) λmax (ε, M-1 cm-1) = 456 (38040), 429 (30920), 259
(50960). Fluorescence emission (CHCl3, λexc = 456 nm) λem(Irel) =
467(1) nm, 496(0.59) nm.
Synthesis of 2a. KSCN (0.010 g, 0.109 mmol) was added to the
stirred solution of 1a (0.070 g, 0.09 mmol) in 20 mL of acetone
under N2 atmosphere. After 12 h, the solvent was distilled off,
and the residue was redissolved in a minimal amount of dichlor-
omethane, and the cloudy solution was filtered through a
Kieselguhr filter. Complex 2a was precipitated by the addition
of methanol (30 mL) as a yellow solid. Yield: 0.05 g, 72%. Anal.
Calcd for C33H41NP2PtS: C, 53.51; H, 5.58; N, 1.89. Found: C,
53.51; H, 5.27; N, 1.99. 1H NMR (300 MHz, CDCl3): δ 8.43 (d,
J = 8.1 Hz, 1H), 8.17-8.10 (m, 3H), 7.81 (d, J = 7.5 Hz, 1H),
7.65-7.59 (m, 2H), 7.50-7.38 (m, 4H), 1.64-1.46 (m, 12H,
CH2CH3), 1.13-1.03 (m, 18H, CH2CH3). 31P{1H} NMR
(CDCl3): δ 14.56 (s, JPPt = 2740 Hz). IR (KBr) ν (NdCdS) =
2099 cm-1. UV/vis (CHCl3) λmax (ε, M-1 cm-1) = 464 (28400),
438 (26330), 260 (33330), 240 (28622). Fluorescence emission
(CHCl3, λexc = 464 nm) λem(Irel) = 482(1) nm, 511(0.67) nm.
Synthesis of 3a. Freshly prepared silver cyanide [obtained
from AgNO3 (0.020 g, 0.11 mmol) and KCN (0.080 g, 0.11
mmol)] and 1a (0.070 g, 0.091 mmol) in acetone (20 mL) were
stirred for 12 h in the dark, under N2 atmosphere. The solvent
was then evaporated, the residue was redissolved in dichloro-
methane (ca. 20 mL), and the cloudy solution was filtered
through a Kieselguhr filter. The yellow solid 3a was precipitated
by the addition of 30 mL of methanol. Yield: 0.05 g, 78%. Anal.
Calcd for C33H41NP2Pt: C, 55.93; H, 5.83; N, 1.89. Found: C,
55.57; H, 5.55; N, 1.75. 1H NMR (300 MHz, CDCl3): δ 8.24 (d,
J = 8.0 Hz, 1H), 8.16-8.09 (m, 3H), 7.90 (d, J = 7.5 Hz, 1H),
7.64-7.58 (m, 2H), 7.49-7.35 (m, 4H), 1.76-1.62 (m, 12H,
CH2CH3), 1.12-1.01 (m, 18H, CH2CH3). 31P{1H} NMR
(CHCl3): δ 11.16 (s, JPPt = 2590 Hz). IR (KBr) ν (NtC) =
2116 cm-1. UV/vis (CHCl3) λmax (ε, M-1 cm-1) = 463 (31730),
437 (29100), 257 (38700), 240 (24910). Fluorescence emission
(CHCl3, λexc = 462 nm) λem(Irel) = 479(1) nm, 510(0.65) nm.
Synthesis of 4a. Complex 1a (0.250 g, 0.33 mmol) and AgNO3
(0.060 g, 0.33 mmol) in 60 mL of acetone under N2 atmosphere
were placed in a Schlenk flask. The reaction was stirred for 3 h in
the dark, after which the reaction mixture was evaporated to
dryness. The residue was redissolved in dichloromethane (ca. 20
mL), and the cloudy solution was filtered through a Kieselguhr
filter. The brown solid 4a was precipitated by the addition of
methanol. Yield: 0.200 g, 81%. Anal. Calcd for C32H41NO3-
P2Pt: C, 51.61; H, 5.55; N, 1.88. Found: C, 51.21; H, 5.20; N,
1.76. 1H NMR (300 MHz, CDCl3) δ 8.74 (d, J = 7.9 Hz, 1H),
8.18-8.12 (m, 3H), 7.79 (d, J = 7.9 Hz, 1H), 7.66-7.39 (m, 6H),
1.55-1.40 (m, 12H, CH2CH3), 1.13-1.03 (m, 18H, CH2CH3).
31P{1H} NMR (CDCl3): δ 17.24 (s, JPPt = 2841 Hz). UV/vis
(CHCl3) λmax (ε, M-1 cm-1) = 464 (28750), 438 (25960), 260
Synthesis of 6a. To a suspension of 4a (0.040 g, 0.053 mmol) in
5 mL of acetone and in 5 mL of H2O under N2 atmosphere was
added 4-methylpiridine (5 μL, 0.21 mmol). The solution was
stirred for 12 h, then KPF6 (0.020 g, 0.11 mmol) was added. The
reaction mixture was concentrated, and a yellow solid precipi-
tated. The precipitate was filtered and washed with H2O (2 ꢀ
3 mL). The solid was redissolved in dichloromethane (20 mL),
and the solution dried with magnesium sulfate. The solution was
filtered, and the solvent was then removed in vacuum, yielding
6a as a yellow solid. Yield: 0.03 g, 62%.
Anal. Calcd for C38H48NF6P3Pt: C, 49.57; H, 5.25; N, 1.52.
Found: C, 49.37; H, 5.16; N, 1.41. 1H NMR (400 MHz, CDCl3):
δ 8.71 (d, J = 5.8 Hz, 1H), 8.60 (d, J = 5.5, 1H), 8.55 (d, J =
8.06, 1H), 8.19-8.15 (m, 3H), 7.90 (d, J = 7.5 Hz, 1H),
7.68-7.43 (m, 8H), 2.54 (s, 3H, CH3), 1.27-1.21 (m, 12H,
CH2CH3), 1.09-1.01 (m, 18H, CH2CH3).31P{1H} NMR
(CHCl3): δ 11.74 (s, JPPt = 2662 Hz), δ-143.71 (septuplet,
J
PF =712Hz). UV/vis(CHCl3) λmax (ε, M-1 cm-1) = 460 (33370),
432 (27540), 260 (46400). Fluorescence emission (CHCl3, λexc
459 nm) λem(Irel) = 473(1) nm, 501(0.62) nm.
=
Synthesis of 1b. To a solution of [Pt(PEt3)4] (0.113 g, 0.17 mmol)
in THF (20 mL) under a N2 atmosphere was added N-(2,5-di-
tert-butylphenyl)-9-bromo-perylene-3,4-dicarboximide (0.100 g,
0.17 mmol). The red solution was stirred 6 h, then the solvent
was removed in vacuum. The purple residue was washed with
pentane (3 ꢀ 15 mL) and recrystallized from CH2Cl2/MeOH.
The purple precipitate 2b was dried in vacuum. Yield: 0.130 g,
75%. Anal. Calcd for C48H60NBrO2P2Pt: C, 56.53; H, 5.13; N,
1
1.37. Found: C, 56.27; H, 5.40; N, 1.37. H NMR (400 MHz,
CDCl3): δ8.87 (d, J = 8.3 Hz, H4), 8.63 (d, J = 8.1 Hz, H7), 8.60
(d, J = 8.1 Hz, H11), 8.47 (d, J = 8.3 Hz, H6), 8.46 (d, J =
8.1 Hz, H8), 8.41 (d, J = 8.3 Hz, H12), 8.08 (d, J = 7.9 Hz, H1),
7.86 (d, J = 7.5 Hz, H2), 7.60 (t, J = 8.1 Hz, H5), 7.58 (d, J =
8.5 Hz, H13), 7.45 (dd, J = 8.4, J = 2.2 Hz, H14), 7.05 (d, J =
t
2.2, H15), 1.73-1.60 (m, 12H, CH2CH3), 1.33 (s, 9H, Bu),
1.28 (s, 9H, tBu), 1.10-1.02 (m, 18H, CH2CH3). 31P{1H}
NMR (CDCl3): δ 12.12 (s, JPPt = 2666 Hz). IR (KBr, cm-1):
ν 1699(CdO), 1657(CdO). UV/vis (CHCl3) λmax (ε, M-1 cm-1) =
543 (38840), 275 (82920), 241 (59530). Fluorescence emission
(CHCl3, λexc = 542 nm) λem(Irel) = 618(1) nm, 659(0.65) nm.
Synthesis of 4b. A mixture of 1b (0.250 g, 0.26 mmol) and
AgNO3 (0.050 g, 0.29 mmol) in 50 mL of acetone, under N2
atmosphere and shielded from light, was stirred 2 h, then the solvent
was removed in vacuum. The solid was redissolved in dichloro-
methane, and the cloudy solution was filtered through a Kieselguhr
filter. The purple solid 4b was precipitated by addition of diethyl
ether. Yield: 0.211 g, 86%. Anal. Calcd for C48H60N2O5P2Pt: C,
61.33; H, 6.43; N, 2.98. Found: 61.08; H, 6.30; N, 2.74. 1H NMR
(400 MHz, CDCl3): δ 9.02 (d, J = 8.3 Hz, H4), 8.63 (d, J = 8.1 Hz,
H7), 8.60(d, J=8.1Hz, H11), 8.48(d, J=8.1Hz, H8), 8.46(d, J=
8.1 Hz, H6), 8.41(d, J=8.1Hz, H12), 8.06(d, J=7.8Hz, H1), 7.77
(d,J=7.8Hz,H2),7.66(d,J=7.8Hz,H5),7.58(d,J=8.6Hz,H13),
(27010), 253 (26490). Fluorescence emission (CHCl3, λexc
467 nm) λem (Irel) = 488(1) nm, 517(0.67) nm.
=
Synthesis of 5a. To a suspension of 4a (0.080 g, 0.107 mmol) in
20 mL of acetone/water (1:1) under N2 atmosphere was added
CNtBu (24 μL, 0.21 mmol). The solution was stirred for 12 h,
and then KPF6 (0.040 g, 0.21 mmol) was added. The reaction
mixture was concentrated and a yellow solid precipitated, which

Article
Inorganic Chemistry, Vol. 49, No. 20, 2010 9177
Table 5. Crystal and Structure Refinement Data for 2a, 5a, and 4b
2a
4b
5a CH2Cl2
3
empirical formula
formula weight
temperature (K)
wavelength (A)
crystal system
space group
a (A)
b (A)
c (A)
R (deg)
β (deg)
C33H41NP2PtS
740.76
298(2)
0.71073
monoclinic
P2(1)/n
10.2893(16)
14.623(2)
21.444(3)
90
100.554(3)
90
3171.9(8)
4
1.551
4.613
1480
0.21 ꢀ 0.06 ꢀ 0.05
1.69 to 26.37°
27124
C48H60N2O5P2Pt
1002.01
298(2)
0.71073
monoclinic
P2(1)/n
14.047(3)
19.975(4)
16.215(3)
90
90.672(3)
90
4549.7(14)
4
1.463
3.201
2040
0.37 ꢀ 0.11 ꢀ 0.10
1.62 to 26.38°
39476
C38H52Cl2F6NP3Pt
995,71
298(2)
0.71073
monoclinic
P2(1)/n
17.077(8)
14.366(7)
17.372(8)
90
99.957(9)
90
4198(3)
4
1.576
3.639
1992
0.41 ꢀ 0.30 ꢀ 0.07
1.84 to 27.50°
39268
γ (deg)
V (A3)
Z
Dcalc (g cm-3
)
absorpt. coefficient (mm-1
F(000)
crystal size (mm)
)
θ range for data collection
reflections collected
independent reflections
absorption correction
maximum and minimum transmission factor
data/restraints/parameters
goodness-of-fit on F2
6473
9311
9643
SADABS
0.7940 and 0.5489
6473/231/398
1.007
SADABS
1.000000 and 0.663169
9311/0/535
1.030
SADABS
0.9806 and 0.5628
9643/16/489
1.020
R1 [I >2σ(I)]
wR2 (all data)
0.0554
0.1706
0.0347
0.0963
0.0446
0.1197
7.44 (dd, J = 8.6 Hz, J = 2.0 Hz, H14), 7.04 (d, J = 2.2 Hz, H15), δ
1.52-1.37 (m, 12H, CH2CH3), δ 1.33 (s, 9H, tBu), δ 1.28 (s, 9H,
tBu), δ 1.15-1.06 (m, 18H, CH2CH3). 31P{1H} NMR (CDCl3): δ
17.02 (s, JPPt = 2795 Hz). IR (KBr, cm-1): ν = 1699 (CdO), 1656
(CdO). UV/vis (CHCl3) λmax (ε, M-1 cm-1) = 545 (36650), 276
(59300). Fluorescence emission (CHCl3, λexc= 542 nm) λem(Irel) =
619(1) nm, 660(0.50) nm.
solved by direct methods with SHELXTL.49 Semiempirical
absorption correction was made with SADABS.50 All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms
were set in calculated positions and refined as riding atoms, with
a common thermal parameter. All calculations were made with
SHELXTL. In the structures of compounds 2a and 4b it was
found that the ethyl groups of the PEt3 ligands were affected by
disorder, which was possible to model in some cases. More
details are given in the Supporting Information and cif file.
Crystallographic data (excluding structure factors) for the
structures reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as Supplementary
publications with the following deposition numbers: CCDC
759812, 759813, and 759814 for complexes 2a, 4b, and 5a,
respectively. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.
cam.ac.uk/data_request/cif.
Synthesis of 5b. To a suspension of 4b (0.080 g, 0.08 mmol) in
10 mL of acetone and 10 mL of H2O under N2 atmosphere was
added CNtBu (18 μL, 0.16 mmol). The red solution was stirred for
12 h and then KPF6 (0.040 g, 0.21 mmol) was added. After 30 min,
the reaction mixture was concentrated, and a red solid precipitated,
which was filtered and washed with H2O (2 ꢀ 3 mL). The solid was
redissolved in CH2Cl2, and the solution dried with magnesium
sulfate. The solution was filtered, and the solvent was then removed
in vacuum. The solid was recrystallized from CH2Cl2/diethyl ether
affording a red precipitate 5b, which was vacuum-dried. Yield:
0.069 g, 79%. Anal. Calcd for C53H69N2F6O2P3Pt: C, 54.50;
1
Acknowledgment. We thank Dr. Emilio Palomares and
H, 5.95; N, 2.40. Found: C, 54.20; H, 5.77; N, 2.23. H NMR
(400 MHz, CD2Cl2): δ 8.61 (d, J = 8.3 Hz, H7), 8.59 (d, J =
8.1 Hz, H11), 8.52(d, J=8.3Hz, H8), 8.51(d, J=8.3Hz, H6), 8.49
(d, J = 8.3 Hz, H12), 8.29 (d, J = 7.6 Hz, H1), 8.25 (d, J = 8.1 Hz,
H4), 7.67 (t, J = 7.8 Hz, H5), 7.60 (d, J = 8.6 Hz, H2), 7.60 (d, J =
8.6 Hz, H15), 7.48 (dd, J = 2.3 Hz, J = 8.6 Hz, H14), 7.03 (d, J =
2.3 Hz, H13), 1.8-1.6 (m, 21H, CH2CH3, CNtBu, 1.33 (s, 9H, tBu),
1.28 (s, 9H, tBu), 1.15-1.06 (m, 18H, CH2CH3). 31P{1H} NMR
ꢀ
Dr. Javier Perez for some spectral measurements, Prof. Dr.
Larry Falvello for advice in the resolution of the X-ray diffrac-
ꢀ
tion structures, and the Spanish Comision Interministerial de
Ciencia y Tecnologıa (CTQ2008-03954/BQU and MAT2008-
06522-C02-02), INTECAT Consolider Ingenio 2010 (CSD2006-
´
ꢀ
0003), and the Junta de Castilla y Leon (Project VA012A08 and
GR169) for financial support.
(CHCl3): δ 11.75 (s, JPPt = 2382 Hz), -143.69 (septuplet, JPF
=
713 Hz). IR (KBr, cm-1): ν 2194 (CtN), 1699 (CdO), 1656
(CdO). UV/vis (CHCl3) λmax (ε, M-1 cm-1) = 515 (42350), 271
(34220), 243 (43350). Fluorescence emission (CHCl3, λexc= 517
nm) λem(Irel) = 581(1) nm, 620(0.55) nm.
X-ray Crystal Structure Analysis. Single crystals of 2a suitable
for X-ray diffraction studies were obtained from slow diffusion
of hexane into a dichloromethane solution of the crude products
Supporting Information Available: Intermolecular contacts
detected in 4b, split Figure 2-above in two, absorption and
emission spectra of 1a and 1b in different solvents, excitation
spectra, Cyclic voltammogram of compounds 1a and 5b, and
refinement details of the X-ray Crystal Structure Analysis of 2a
and 5a. This material is available free of charge via the Internet
at http://pubs.acs.org.
at -20 °C, under nitrogen. Crystals from 4b and 5a CH2Cl2
3
(48) SAINTþ; SAX area detector integration program, Version 6.02;
Bruker AXS, Inc.: Madison, WI, 1999.
(49) Sheldrick, G. M. SHELXTL, An integrated system for solving,
refining, and displaying crystal structures from diffraction data, Version 5.1;
Bruker AXS, Inc.: Madison, WI, 1998.
(50) Sheldrick, G. M. SADABS, Empirical Absorption Correction Program;
University of G€ottingen: G€ottingen, Germany, 1997.
were grown from slow diffusion of Et2O into a dichloromethane
solution of the products at -20 °C, under N2 atmosphere. Data
were taken on a Bruker AXS SMART 1000 CCD diffract-
ometer, using φ and ω scans, MoKR radiation (λ = 0.71073 A),
graphite monochromator, and T=298 K. Raw frame data were
integrated with SAINT48 program. Structures (Table 5) were