Facile metalation of Hbzq by [ cis -Pt(C6F5) 2(thf)2]: A route to a pentafluorophenyl benzoquinolate solvate complex that easily coordinates terminal alkynes. Spectroscopic and optical properties

Article abstract of DOI:10.1021/ic301563u

A new neutral cyclometalated platinum(II) solvate complex [cis-Pt(bzq)(C₆F₅)(acetone)] (1) has been prepared by easy C-H activation of 7,8-benzo[h]quinoline on the coordination sphere of [cis-Pt(C₆F₅)₂(thf)₂] (thf = tetrahydrofuran). The study of the reaction pathway has led us to the preparation of the bis(Hbzq) product [cis-Pt(C₆F₅) ₂(Hbzq)₂] (2) and the benzoquinoline-benzoquinolate derivative [Pt(bzq)(C₆F₅)(Hbzq)] (3). This latter complex has been characterized by X-ray diffraction, showing the occurrence of π...π intermolecular stacking interactions associated to the deprotonated bzq units. The acetone molecule in [cis-Pt(bzq)(C₆F ₅)(acetone)] can be easily displaced by alkynes, allowing the synthesis of the first reported η²-alkyne-cycloplatinate complexes [Pt(bzq)(C₆F₅)(η²- RC≡CR′)] (R = H, R′ = Ph 4, ^tBu 5, Fc 6; R = R′ = Ph 7), which have been fully characterized spectroscopically and by DFT studies. These alkyne complexes are only moderately stable in solution, and all attempts to obtain crystals suitable for X-ray diffraction were fruitless. Nevertheless, in the case of the ferrocenyl derivative, crystals of complex [Pt(κN: η²-bzq-C≡CFc)(C₆F ₅)(μ-κC^α:η²-C≡CFc) Pt(bzq)(C₆F₅)] (8), containing an unusual alkynyl-functionalized benzoquinoline chelate ligand, were systematically obtained. All complexes (except those containing the ferrocenyl fragment) present emissive properties in solution and solid state (77 K), related, in general, with intraligand (bzq) excited states with some mixing ³MLCT character, as supported by theoretical calculations. In solid state at room temperature, aggregation induced emission (AIE) is observed likely generated by intermolecular π...π stacking, as supporting by DFT calculations on 3₂. Interestingly, both types of excited states (³IL/ ³MLCT and AIE) seem to be close in energy in complexes 1 and 3, which show a significant luminescent thermochromism (green 77 K to orange 298 K).

Full text of DOI:10.1021/ic301563u

Article
pubs.acs.org/IC
Facile Metalation of Hbzq by [cis-Pt(C6F5)2(thf)2]: A Route to a
Pentafluorophenyl Benzoquinolate Solvate Complex That Easily
Coordinates Terminal Alkynes. Spectroscopic and Optical Properties†
Jesus R. Berenguer, Elena Lalinde,* M. Teresa Moreno, Sergio Sanchez, and Javier Torroba
́
́
Departamento de QuímicaGrupo de Síntesis Química de La Rioja, UA-CSIC, Universidad de La Rioja, 26006 Logrono, Spain
̃
S
* Supporting Information
ABSTRACT: A new neutral cyclometalated platinum(II)
solvate complex [cis-Pt(bzq)(C6F5)(acetone)] (1) has been
prepared by easy C−H activation of 7,8-benzo[h]quinoline on
the coordination sphere of [cis-Pt(C6F5)2(thf)2] (thf =
tetrahydrofuran). The study of the reaction pathway has led
us to the preparation of the bis(Hbzq) product [cis-
Pt(C6F5)2(Hbzq)2] (2) and the benzoquinoline−benzoquino-
late derivative [Pt(bzq)(C6F5)(Hbzq)] (3). This latter
complex has been characterized by X-ray diffraction, showing
the occurrence of π···π intermolecular stacking interactions
associated to the deprotonated bzq units. The acetone molecule in [cis-Pt(bzq)(C6F5)(acetone)] can be easily displaced by
alkynes, allowing the synthesis of the first reported η2-alkyne-cycloplatinate complexes [Pt(bzq)(C6F5)(η2-RCCR′)] (R = H,
R′ = Ph 4, tBu 5, Fc 6; R = R′ = Ph 7), which have been fully characterized spectroscopically and by DFT studies. These alkyne
complexes are only moderately stable in solution, and all attempts to obtain crystals suitable for X-ray diffraction were fruitless.
Nevertheless, in the case of the ferrocenyl derivative, crystals of complex [Pt(κN:η2-bzq-C≡CFc)(C6F5)(μ-κCα:η2-
C≡CFc)Pt(bzq)(C6F5)] (8), containing an unusual alkynyl-functionalized benzoquinoline chelate ligand, were systematically
obtained. All complexes (except those containing the ferrocenyl fragment) present emissive properties in solution and solid state
(77 K), related, in general, with intraligand (bzq) excited states with some mixing 3MLCT character, as supported by theoretical
calculations. In solid state at room temperature, aggregation induced emission (AIE) is observed likely generated by
intermolecular π···π stacking, as supporting by DFT calculations on 32. Interestingly, both types of excited states (3IL/3MLCT
and AIE) seem to be close in energy in complexes 1 and 3, which show a significant luminescent thermochromism (green 77 K
to orange 298 K).
energies, thus favoring phosphorescence from a variety of
lowest triplet excited states, including ligand centered (LC),
charge transfer (MLCT, LL′CT), or metal-metal-to-ligand
charge transfer (MMLCT) excited states. The coligands may
have also a remarkable effect on the characteristics of the lowest
excited state, and to date, the most common auxiliary ligands
used are β-diketonates (O∧O),7 phosphines, and related strong
field ligands such as alkynyl (CCR−), CO, CNR, and
CN−.2,8
On the other hand, alkyl and aryl heteroleptic platinum(II)
complexes with cyclometalating (C∧N) ligands have also
attracted the attention of many chemists.9 The synthesis of
these complexes often requires selective intramolecular C−X
(X = H, halide) bond activation, and on many occasions, they
are involved in C−C bond coupling processes, which are
among the most pursued goals in transition metal chemistry.9,10
The interest in these systems has mainly focused on synthetic
strategies and mechanistic aspects, and little is known about
their optical properties.9k,l In our continued efforts to design
INTRODUCTION
■
The search for new emitting coordination complexes is
currently attracting widespread interest from both the stand-
point of fundamental properties and their potential in the
development of optoelectronic devices.1 In this area, a
significant effort has focused on the design and synthesis of
square-planar platinum(II) complexes containing alkynyl,
polypyridyl, and/or cyclometalating ligands, due to their rich
and readily tunable photophysical properties, as well as their
tendency to form metal−metal and π−π stacking interactions.
Several recent reviews cover different aspects of these
complexes, including the nature of their excited states and
the wide variety of promising applications.2 In particular,
cyclometalating (C∧N, N∧C∧N, C∧N∧N, C∧N∧C) platinum
complexes have shown potential in highly efficient organic
light-emitting diode (OLED) devices,2,3 as luminescent
molecular sensors and in biological labeling2,4 and photo-
catalysis.5 For these complexes the photophysical properties are
usually determined by the nature and the degree of conjugation
of the cyclometalating ligand.2,6 In general, the strong field
nature of the cyclometalating ligand pushes the undesired
nonradiative metal centered (d−d) excited states to higher
Received: July 18, 2012
Published: October 18, 2012
© 2012 American Chemical Society
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Scheme 1
homo- and heteropolynuclear luminescent benzoquinolate
platinum(II) complexes, Fornies and Lalinde et al. previously
́
Among the variety of platinum substrates, common starting
materials for cycloplatination are species containing labile
ligands, [cis-PtX2S2] (X = Cl, R; S = SMe2, NCMe, dmso, and
so forth), and dimeric complexes, [PtR2(μ-SMe2)]2 (R = Me,
Aryl), because they enable the required initial N-coordination
of the HC∧N ligand. By using these precursors, a number of
neutral alkyl and aryl cycloplatinate complexes [Pt(C∧N)RS]
(S = labile solvent)9 and very interesting series of rollover
N′(3) mono- and polynuclear platinum complexes,9d,e,17
generated by unusual cyclometalation of 6-substituted, and
unsubstituted 2,2′-bypiridyne ligands, have been reported. On
the contrary, and probably due to the higher thermal stability of
perfluoro organyl RF-platinum bonds, reports related to the
reported the anionic derivative (NBu4)[Pt(bzq)(C6F5)2], which
has been shown to be not only an efficient green emitter,11 but
also an excellent precursor to polymetallic species stabilized by
Pt→M donor bonds and in some cases η1-C(bzq)···M bonding
interactions.11,12 In this contribution, we report on the
synthesis of two neutral pentafluorophenyl benzoquinolate
complexes [Pt(bzq)(C6F5)L] (L = acetone 1, Hbzq 3), which
are related to the N,N coordinated complex [cis-Pt-
(C6F5)2(Hbzq)2], 2, as well as on their photophysical
properties. We also sought to probe the feasibility of the
substitution of the acetone solvent in complex 1 for alkynes.
The rationale of our choice mainly rests on the knowledge that
Pt(II)-alkynes, in particular with terminal alkynes, are very
rare,13 and to the best of our knowledge, there is no report on
terminal alkynes coordinated to a cycloplatinated fragment.14
Here we wish to report on the synthesis, characterization, and
optical properties of the η2-alkyne complexes [Pt(bzq)(C6F5)-
cyclometalation of potential N-ligands by [cis-PtRF S2] are very
2
rare.9b,18 The first example was published by Professor Fornies
́
in 1992, who reported (Scheme 1a) the synthesis of complex
[Pt(C6F5)(C6H4C(Ph)NNCPh2)], A, containing the
deprotonated benzophenone azine acting as tridentate κ2C,N-
18
η2(phenyl) ligand. More recently, Crespo and Martinez et al.
́
t
(HCCR)] (R = Ph 4, Bu 5, Fc 6) and [Pt(bzq)(C6F5)-
have found that the reaction of [cis-Pt(C6F5)2S2] (S = SEt2,
SMe2) with the imine 2-BrC6H4CHNCH2(4′-ClC6H4)
(Scheme 1b) evolves with final formation of Pt(II) metalated
complexes [PtBr{6-C6F5)(2-C)C5H3CHN-CH2(4′-ClC6H4)}-
S], containing a biaryl linkage involving one of the C6F5
groups.9b In this context and aiming to obtain a solvate
monopentafluorophenylbenzoquinolate complex, we decide to
investigate the reactivity of [cis-Pt(C6F5)2(thf)2] (thf =
tetrahydrofuran) toward 7,8-benzo[h]quinoline.
As is shown in eq 1, the reaction of [cis-Pt(C6F5)2(thf)2] with
1 equiv of 7,8-benzoquinoline in refluxing acetone for 2.5 h
renders the benzoquinolate complex 1 in almost quantitative
yield (97%). The structure of complex 1 was based on
spectroscopic data (1H, 19F, 13C{1H}), mass spectrometry, and
elemental analysis. In particular, the very high value of the
195Pt−Fortho coupling constant (501 Hz) found in the 19F NMR
spectrum is consistent with the N atom in trans position to the
Cipso atom of the C6F5 group. The selective formation of this
(PhCCPh)], 7, as well as on the unusual formation of the
diplatinum complex [Pt(κN:η2-bzq-CCFc)(C6F5)(μ-κCα:η2-
CCFc)Pt(bzq)(C6F5)], 8, containing a rare functionalized
akynyl-benzoquinoline (bzq-CCFc)-10 as a chelating κN:η2-
CC ligand.
RESULT AND DISCUSSION
■
Preparation and Characterization of Complexes 1−3.
Efficient cyclometalation promoted by transition metal
complexes remains one of the most challenging fields in
modern chemistry, because of its many successful applications
in organic synthesis.10,15 In this area, since the first report of a
platinum(II) complex containing a N∧C orthometalated
ligand,16 the study of this kind of cycloplatinated system has
experienced continuous growing, giving rise not only to a wide
range of interesting complexes, but also to many mechanistic
details of the C−H bond activation in cyclometalation.10,15
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coordination product [cis-Pt(C6F5)2(Hbzq)2], 2, was formed
(Scheme 2). The mixture converts slowly and almost
quantitatively (∼2 h) into the cyclometalated derivative 1
with formal elimination of C6F5H, as observed by 19F NMR
spectroscopy. No other intermediate was detected. The
formation of the saturated complex 2 is likely related to the
presence of very weakly coordinating tetrahydrofuran mole-
cules in the precursor, which facilitates the disubstitution and
formation of two relatively strong Pt−N bonds, making 2
thermodynamically more stable than the monosubstitution
complex [cis-Pt(C6F5)2(Hbzq)S]. Similar saturated and stable
coordination palladium complexes of type [M(E−CR)2Xn]
have been detected and isolated in cyclometalation processes.20
Probably, the excessive crowding around platinum in complex 2
facilitates the transient decoordination of one of the Hbzq
ligands, yielding the coordinatively unsaturated 14 electron
complex 2′ as the key intermediate. The final C−H bond
activation in 2′ could be facilitated by the fact that the rigid 7,8-
benzo[h]quinoline is expected to be roughly perpendicular to
the coordination plane, allowing the C10′−H vector to be close
to the Pt center (Scheme 2).21
In order to confirm that complex 2 is an adequate precursor
for the preparation of 1, it was independently generated, as a
yellow solid, by reaction of [cis-Pt(C6F5)2(thf)2] with 2 equiv of
Hbzq (Scheme 3i). Although its formation is immediate and
quantitative, the synthesis and characterization of 2 must be
carried out at low temperature (see Experimental Section),
because it is unstable in solution, evolving even at low
temperature to the new cyclometalated complex [Pt(bzq)-
(C6F5)(Hbzq)], 3 (Scheme 3ii). Complex 2 was found to react,
even at room temperature, with 1 equiv of the solvate [cis-
Pt(C6F5)2(thf)2] in acetone yielding 1 (Scheme 3iii), and as
was expected, the acetone molecule in 1 can be replaced by
Hbzq to directly give 3 in very high yield (75%, Scheme 3iv).
Despite of many efforts to crystallize these 1−3 complexes, we
geometric isomer is coherent with the well-known transphobia
effect,8e,19 which places the ligand of lower trans influence
(acetone solvent) trans to the metalated C10 atom. The
1
complete H and 13C assignment of the deprotonated bzq
ligand was performed on the basis of 2D-NMR experiments
1
(1H−1H COSY, H−13C HSQC and HMBC; see Figure S1 in
Supporting Information). Thus, the H9 proton is observed,
flanked by Pt satellites, relatively upfield (δ 6.90) on account of
the expected anisotropic effect of the C6F5 ring. The very high
195Pt coupling constant for this H9 proton (3JPt−H = 70 Hz) is
also consistent with the CH3COCH3 coordinated (δH 2.06; δC
31.6 and 206.8) trans to the C10-metalated carbon atom (δ
142.8). For previously studied reactions between [cis-Pt-
(Ar)2S2] (Ar = C6H3Me2-3,5; C6H3(CF3)2-3,5; Ph; S = dmso,
NCMe) and 2-arylpyridine ligands (HPhpy, HCF3Phpy), it has
been shown that the reaction involves the formation of
intermediate complexes [cis-Pt(Ar)2(HPhpy)S] having a
monodentate HPhpy ligand (detected by NMR spectroscopy
and characterized by X-ray for complex [cis-Pt(C6H3Me2-
3,5)2(HPhCF3py)(dmso)]9a). The final monoaryl cycloplati-
nated complexes were suggested to be formed from this
intermediate by intramolecular oxidative addition of the C−H
to the Pt(II), followed by arene reductive elimination. To get
more insight in the reaction pathway leading to complex 1, the
1
reaction was monitored by H and 19F NMR spectroscopy in
acetone-d6. Interestingly, when 1 equiv of Hbzq is added to [cis-
Pt(C6F5)2(thf)2] at room temperature, a clean equimolar
mixture of the solvate precursor and the bis(Hbzq)
Scheme 2
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Scheme 3
only were successful in obtaining suitable X-ray analysis crystals
for 3·0.25CH2Cl2 (Figure 1).
chemistry with a benzoquinoline acting as monodentate N-
ligand. The roughly orthogonal coordination of the Hbzq
ligand (dihedral angle 65.7°) places the H(10′) proton in a
pseudoaxial position above the platinum coordination plane,
being the Pt(1)−H(10′) vector which deviated only 23.4(1)°
from the normal to this plane. The Pt(1)−C(10′) [3.241(9) Å]
and Pt(1)−H(10′) [2.4508(3) Å] separations are comparable
to those found in [trans-PtCl2(Hbzq)(PEt3)] [Pt−C 3.189(7)
Å; Pt−H ∼2.53(8) Å], and fall in the range in which similar
Pt···H bonding interactions have been reported in the
literature.19b,22,23 The Pt(1)···H(10′)−C(10′) is 142.9(6)°.
Also interesting is the supramolecular packing of the platinum
molecules, which stack in a head-to-head manner supported by
π···π(bzq) interactions [∼ 3.5 Å; minimum C···C distance
3.46(1) Å] to give a columnar disposition through the a-axis
(Figure 2), having influence on the luminescence properties of
the complex (see Photophysical Studies section). Further
inspection of the crystal structure reveals the presence of other
types of noncovalent interactions [π....π(C6F5), C−H···F]
generating a supramolecular 3-D network with vacant channels
along the a-axis, in which the crystallization CH2Cl2 molecules
accommodate (Figure S2 in Supporting Information).
Analytical and relevant spectroscopic data for 2 and 3 are
collected in the Experimental Section and Supporting
Information (1H NMR spectra). For 2 two different conformers
with the benzoquinoline ligand adopting a syn or an anti
arrangement can be assumed (see Scheme 2), with the latter
being more likely on the basis of steric (less π···π repulsion
between the aromatic rings) and electronic (well directed Pt→
H−C10′ interactions) grounds. The 1H and 19F NMR spectra of
2 confirm the presence of only one set of signals for both
ligands (Hbzq and C6F5), but only at low temperature (−40
°C) is the 19F NMR spectrum consistent with a relatively rigid
molecule in solution, exhibiting the expected set of five fluorine
resonances (AFMRX system). By increasing the temperature,
the two ortho and the two meta resonances broaden and
coalesce (∼293 K for the Fortho and ∼283 K for the Fmeta, ΔG⧧
∼ 56.8 kJmol−1), giving rise at room temperature to just three
Figure 1. ORTEP view of the molecular structure of [Pt(bzq)(C6F5)-
(Hbzq)]·0.25CH2Cl2 (3·0.25CH2Cl2). Ellipsoids are drawn at the 50%
probability level. Hydrogen atoms are omitted for clarity. Selected
bond distances and angles: Pt(1)−N(1′) 2.182(6), Pt(1)−N(1)
2.098(6), Pt(1)−C(10) 1.976(7), Pt(1)−C(15) 2.012(7), N(1)−
Pt(1)−N(1′) 95.2(2), C(10)−Pt(1)−N(1) 81.7(3), C(15)−Pt(1)−
N(1′) 89.3(2), C(15)−Pt(1)−C(10) 93.8(3).
The X-ray structure confirms the C−H activation of one of
the 7,8-benzo[h]quinoline ligands and the N-coordination of
the other one. In accordance with the spectroscopic data, the
C6F5 group is coordinated in cis position to the metalated
C(10) atom. The bond lengths and angles are in the range
found for related complexes.8a−e,11,12 The Pt−N(1′) bond
length with the Hbzq ligand is relatively long [2.182(6) Å],
reflecting the strong trans influence of the metalated C(10)
atom of the bzq. This bond is longer than that found by
Albinati and co-workers in [trans-PtCl2(Hbzq)(PEt3)]22
[2.142(4) Å], the only crystal structure reported in platinum
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absence of free rotation of the C6F5 ring around the Pt−Cipso
bond, probably due to steric hindrance of the Hbzq.
Preparation and Characterization of Alkyne Platinum
Complexes 4−7. The synthesis of platinum alkynyl based
complexes has been extensively researched because of their rich
structural diversity and chemical reactivity, and more recently
because of the potential of these systems in the design of new
molecular site electronic devices.2e,h−m,14,25 Extensive work in
this topic made by our group and others has shown the ability
of metalla-alkynyl (MCCR) and phosphino-alkynes (M
PR2CCR′) to coordinate to Pt(II), leading to a variety of
polynuclear systems, some of which have intriguing photo-
physical properties.2e,k,14a,c,25a,c However, in spite of the
similarity of these units and simple alkynes, the number of
η2-alkyne-Pt(II) complexes remains relatively scarce, and most
of them have been confined to internal alkynes.13,14,24
Experimental evidence supported by theoretical calculations
indicates that the Pt(II)-η2(alkyne) bonding interaction is weak,
probably due to the low dπ back-donation from Pt(II) to the
π*∥ and the presence of a four-electron destabilization
interaction between the occupied π⊥ of the alkyne and the
other symmetry adopted filled metal dπ orbital.26 In fact, the
coordinated terminal alkyne has been found to be reasonably
stabilized only in electron-rich anionic13a,b or five-coordina-
ted13c−e fragments. With cationic and even neutral fragments
the electrophilicity of the alkyne is notably enhanced upon
coordination to Pt(II), providing the access to di-, oligo-, or
polymerization of alkynes or the entry to interesting complexes,
which are usually initiated by nucleophilic attacks or insertion
reactions.14,27 Due to the electronic characteristic of the C6F5
Figure 2. Detail of the intermolecular π···π stacking observed along
the a axis for 3·0.25CH2Cl2.
signals (AA′MXX′ system). The observed pattern at room
temperature suggests that C6F5 rings behave as free rotating, a
process which could take place directly in 2 or via a
tricoordinated transient species 2′ in fast equilibrium with 2.
No detectable change was observed in the coalescence peak by
diluting the sample by a factor of 2, thus excluding the
occurrence of a dissociative process, at least to a significant
extent. We note that the cyclometalation reaction, which
transforms 2 into 3, occurs very easily when the temperature is
close to room temperature. In fact, signals due to 3 were also
visible at the end of the temperature-dependent 19F NMR
studies. Not unexpectedly, the resonance due to the H10′
proton appears (see Figure S3a) notably downfield shifted (δ
12.16) in relation to the free ligand (δ 9.30). In accordance to
previous observations in related complexes, this fact indicates
that the proton H10′ is located in close proximity to the Pt
center in a pseudoaxial position, experiencing the anisotropic
́
groups and strength of the Pt−C6F5 bond, Fornies et al. have
demonstrated that the neutral “cis-Pt(C6F5)2” and the anionic
[Pt(C6F5)3]− fragments are adequate synthons for the isolation
of complexes containing two or one η2-coordinated internal
alkynes.24b,c In this context, we considered of interest (i) the
use of the solvate complex 1, having a C6F5 group, as a
precursor for η2-alkyne complexes, and (ii) the study of the
photophysical properties of the final alkyne−benzoquinolate
species. As possible alkynes we have chosen internal (PhC
CPh) and terminal (HCCPh, HCCtBu, HCCFc) ones.
Complex 1 reacts with equimolar amounts of terminal
alkynes HCCR (R = Ph, tBu, Fc) and with diphenylacetylene
(PhCCPh) in CH2Cl2 to produce the corresponding η2-
alkyne complexes [Pt(bzq)(C6F5)(η2-HCCR)] (R = Ph 4,
tBu 5, Fc 6) and [Pt(bzq)(C6F5)(η2-PhCCPh)] 7,
respectively (Scheme 4 and Experimental Section). Although
all attempts to obtain crystals of complexes 4−7 were
unsuccessful, their formulation as η2-alkyne derivatives shown
in Scheme 4 was clearly confirmed by analytical and
spectroscopic means. The IR spectra show a characteristic
ν(CC) stretching band (1974−2017 cm−1), which is shifted
to lower frequencies in relation to free alkynes (Δν 104−193
cm−1), confirming the η2-coordination of the ligands. Similar
22−24
2
deshielding associated to the Pt dz electron density.
This
arrangement could favor the proton transfer to the Pt center,
lowering the energetic barrier for cyclometalation, in
accordance with the ease cyclometalation observed for complex
2 (2→3). However, despite the remarkable deshielding
observed for H10′, no coupling to 195Pt is observed. As a
consequence, we cannot conclude that a Pt→H interaction
exists in solution.23b,c In the case of 3, the presence of both the
deprotonated bzq− and Hbzq is clearly observed in its proton
NMR spectrum (see Figure S3b for details). As can be seen,
some broadening due to platinum coupling is apparent at the
base of the H10′ signal (δ 12.44), but the expected coupling
cannot be accurately calculated. The presence of five distinct
signals in the 19F NMR spectrum of 3 is a clear indication of the
Scheme 4
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wavenumbers were reported for other platinum(II) alkyne
complexes.13b In the case of 4−6, containing terminal alkyne
ligands, one (3233 4, 3215 cm−1 6) or two (3253, 3245 cm−1
5) ν(CH) stretching bands were also observed, which are
also lowered (Δ 56−68 cm−1) with respect to the free ligands.
Coordination of the terminal alkyne ligands is clearly inferred
from proton NMR spectroscopy. Thus, the terminal acetylenic
protons appear as a singlet in the range δ 4.15−4.91 with
perpendicular to the platinum coordination plane (80.91°) and
a PtC distance (1.911 Å), comparable to those reported, for
instance, in platinum alkoxycarbene compounds.31 The distinct
electronic requirements of both ligands are reflected in the Pt−
C(bzq) bond distances (2.023 Å 4 vs 2.069 Å 4′), which are in
agreement with the lower trans influence of the η2-alkyne
ligand. The comparison of the energies of both isomers
indicates that the alkyne form 4 is ∼9.2 kcal/mol (9.6 kcal/mol
after ZPVE corrections) more stable than the corresponding
vinylidene isomer 4′. This fact, which is a further support of the
formulation of 4−6 as η2-alkyne complexes, may be attributed
to the strong electron-withdrawing properties of the bzq and
C6F5 groups. The presence of these groups and the better π-
acceptor properties of vinylidene ligands relative to alkynes
would disfavor the typical tautomerization observed in other
systems.
characteristic platinum satellites [2J
= 46−50 Hz] (see
195Pt−H
Figure S4 for 4). Interestingly, the observed coordination
induced downfield shift (Δδ 1.83 4, 2.07 5, 1.7 6) is clearly
larger than those reported for anionic complexes [K(18-cr-
6)][PtCl3(HCCR)]13b (Δδ 0.8−1.0 ppm) and some five-
coordinate derivatives such as [PtX2(Me2phen)(η2-HC
CPh)] (Δδ 0.64 ppm).13c However, the values of the platinum
coupling constant are slightly smaller (46−50 Hz in 4−6 vs
66−70 Hz in [K(18-cr-6)][PtCl3(HCCR)] or 54 Hz in
[PtX2(Me2phen)(η2-HCCPh)]), a fact likely due to the
relatively high trans influence of the metalated carbon atom.
Due to solubility reasons, only the 13C{1H} NMR spectrum of
5 was recorded. This complex showed the signals of the two
acetylenic carbons at 65.7 (CH) and 95.1 (tBuC),
respectively, but despite prolonged accumulation no satellites
were observed. The presence of five distinct signals in the 19F
It is worth noting that complexes 4−7 are moderately stable
in solid state, but not in solution. Thus, in tetrahydrofuran only
the tert-butylalkyne complex 5 remains unaltered [δ C−H
4.90, 2JPt−H = 48 Hz]. In this solvent, the alkyne derivatives 4, 6,
1
and 7 and the acetone solvate 1 display identical H (bzq
region) and 19F NMR spectra, thus indicating that these
complexes undergo ligand substitution, to yield the new solvate
species [Pt(bzq)(C6F5)(thf)] in thf solution. In CDCl3
solution, the stability of the terminal alkyne complexes
decreases in the order 5 > 6 > 4, giving rise to a complex
mixture of products in which only complex [Pt(bzq)(C6F5)-
(Hbzq)] (3) and HC6F5 were detected by NMR spectroscopy.
For comparison, after 2 h the most stable 5 remains unaltered,
meanwhile 4 shows decomposition (∼ 10%). After 20 h only
minor decomposition was observed for 5 (∼ 10%), while in the
same time 4 had disappeared completely. The formation of 3
and HC6F5 in solution suggests the occurrence of alkyne (sp)
C−H activation, likely via an oxidative addition, yielding a
Pt(IV) hydride−acetylide pentacoordinate intermediate spe-
cies, which could evolve through sp2 C−H reductive coupling
to form HC6F5 or Hbzq. Ease alkyne substitution by Hbzq in
the precursor would explain the formation of 3.
t
NMR spectrum of 5 (R = Bu) is a clear indication of the
absence of free rotation about both the Pt(II) alkyne and the
Pt−Cipso(C6F5) bonds. However, in the case of complexes 4 and
6 with lesser bulky substituents, the environments of the two
Fortho (and the two Fmeta) atoms are averaged. Although the
observed pattern could be attributed to a lower energetic
barrier to the rotation of the C6F5 ring in these complexes, the
occurrence of free alkyne rotation cannot be excluded.
As has been noted before, terminal alkyne Pt(II) complexes
are very rare, though they have been suggested in many
stoichiometric and catalyst systems as initial transient species
formed by displacement of labile molecules (solvent, olefin) in
the precursors.13b−d,27a,c An easy isomerization of the initial η2-
alkyne to an α-carbocationic or η1-vinylidene species as key
reactive intermediate complex has been proposed to rationalize
the observed nucleophilic addition to the Cα carbon
atom.14c,27c,28 Although some recent theoretical calculations
have been shown that this η2-alkyne to η1-vinylidene
equilibration on the Pt(II) sphere is crucial in some catalytic
processes,29 the experimental evidence is limited to complex
[Pt(CH3)(PPh3)2(CCHPh)]+, which has been detected by
NMR spectroscopy at low temperature.30 In order to rationalize
the formation of the η2-alkyne complexes 4−6, we decided to
examine the relative stability of the [Pt(bzq)(C6F5)(η2-HC
CPh)], 4, and [Pt(bzq)(C6F5)(CCHPh)], 4′, isomers
using density functional theory calculations (DFT). Calcu-
lations were performed (Gaussian03/B3LYP/LanL2DZ) in the
gas phase, and the results are collected in the Supporting
Information (Figure S5, Tables S1−S3). The minimum-energy
structure for both isomers (Figure S5) exhibits the expected
features. For 4, the alkyne is almost perpendicular to the
complex plane (81.72°), with Pt−C (2.282, 2.408 Å) bond
lengths similar to those found in [cis-Pt(C6F5)2(PhCCPh)2]
[2.311(5), 2.269(5) Å],24c but clearly longer to those reported
for anionic alkyne derivatives [PtX3(RCCR)]− (X = Cl,24a
C6F524b) (2.103−2.250 Å),24a,b thus reflecting the enhanced
electrophilic character of the Pt in the neutral “Pt(bzq)(C6F5)”
fragment. As expected, 4′ displays a nearly lineal geometry
(PtCC 176.04°) with the vinylidene plane approximately
As was mentioned above, all attempts to obtain crystals
suitable for X-ray diffraction studies of complexes 4−7 have
been fruitless. Surprisingly, by slow diffusion (∼1 month) of n-
hexane into a CHCl3 solution of the ferrocenylalkynyl
derivative 6 at low temperature (−30 °C), a small amount of
orange crystals grew on the walls, which were identified by
single-crystal X-ray diffraction methods as the unusual dinuclear
product [Pt(κN:η2-bzq-CCFc)(C6F5)(μ-κCα:η2-CCFc)Pt-
(bzq)(C6F5)], 8. Unfortunately, we were not able to isolate
enough of pure complex 8 for a complete spectroscopic
characterization. The molecular structure of 8 is depicted in
Figure 3, and selected structural parameters are given in Table
1. As is shown in Figure 3, in this evolution product 8, the
neutral “Pt(1)(bzq)(C6F5)” fragment is η2 linked to the
ferrocenyl alkynyl ligand of an unexpected ferrocenylacetylide
Pt(2) unit [Pt(2)(bzq-CCFc)(C6F5)(CCFc)], which
contains a rare functionalized 10-ferrocenylethynylbenzo[h]-
quinoline molecule bound in a chelating κN:η2-(CC)
fashion.
Carbon(sp2)−carbon(sp) alkyne coupling is an important
reaction to synthesize asymmetrical alkynes, which is usually
catalyzed by copper salts and/or palladium complexes.32
Nevertheless, though a wide variety of products have been
found by reaction of transition metals with alkynes due to their
very rich chemistry, we are not aware of the formation of a
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notably twisted by coordination of the alkyne unit to Pt(2)
[dihedral angle between the planes formed by the atoms C2′−
N1′−C12′ and C10′−C27−C28 of 67.1(5)°]. The location of
the alkyne unit is constrained by ring limitations, but is
coordinated virtually orthogonal to the coordination plane
[67.5(5)°]. The Pt(2)−alkyne bonds lengths [2.171(9) and
2.228(9) Å] and the back bending at the C(27) [168.2(9)°]
and C(28) [167.3(9)°] alkyne carbons are similar to those
found in other alkyne Pt(II) complexes.24a The Pt···Pt distance
is very long [3.783(1) Å], but the bzq and bzqCCFc are
stacked at relatively close distance [∼ 3.4 Å, minimum C···C
distance 3.40(1) Å, N−N 3.32(1) Å], suggesting the
occurrence of intramolecular π···π interactions. The analysis of
the packing reveals also the presence of intermolecular π···π
interactions (see Figure S6 in Supporting Information).
Photophysical Studies. Absorption Spectra. The data
obtained for the electronic absorption spectra of all complexes
(CH2Cl2 or (2-Me)thf solutions) are summarized in Table S4.
The spectra of 1−3 in (2-Me)thf are shown in Figure 4,
Figure 3. Molecular structure of [Pt(κN:η2-bzq-CCFc)(C6F5)(μ-
κ C α : η 2 - C  C F c ) P t ( b z q ) ( C 6 F 5 ) ] · 2 . 5 C H 2 C l 2 · H 2 O
(8·2.5CH2Cl2·H2O). Ellipsoids are drawn at the 50% probability level.
Hydrogen atoms are omitted for clarity.
Table 1. Selected Distances (Å) and Angles (deg) for
Complex 8·2.5CH2Cl2·H2O
Pt(1)−C(10)
Pt(1)−C(15)
Pt(1)−C(39)
Pt(2)−N(1′)
Pt(2)−C(27)
C(15)−C(16)
C(10′)−C(27)
C(28)−C(29)
2.030(8)
Pt(1)−N(1)
2.108(7)
2.223(9)
1.989(9)
2.014(8)
2.228(9)
1.441(12)
1.227(12)
2.247(10) Pt(1)−C(16)
1.995(8)
2.146(6)
2.171(9)
Pt(2)−C(15)
Pt(2)−C(45)
Pt(2)−C(28)
1.219(12) C(16)−C(17)
1.438(11) C(27)−C(28)
1.425(12)
N(1)−Pt(1)−C(10)
N(1′)−Pt(2)−C(15)
Pt(2)−C(15)−C(16)
80.9(3)
96.9(3)
160.4(9)
C(39)−Pt(1)−C(10)
C(15)−Pt(2)−C(45)
C(15)−C(16)−C(17) 155.4(10)
C(27)−C(28)−C(29) 167.3(9)
85.5(3)
92.7(3)
Figure 4. Normalized UV−vis absorption spectra of 1−3 in (2-Me)thf
(5 × 10−5 M) at 298 K. In the inset: low-energy region.
C(10′)−C(27)−C(28) 168.2(9)
coordinated functionalized alkynyl-benzoquinoline molecule
such as bzq(CCFc)-10. The formation of the ferrocenyl
ethynylbenzo[h]quinoline implies a formal C(sp2)−C(sp)
coupling, which is likely caused by an initial C−H alkyne
activation via oxidative addition to the Pt(II)(2) center, which
end up with C(bzq)−C(alkyne) reductive elimination. The
presence of an additional CCFc group σ-bonded to Pt(2)
indicates a formal hydrogen elimination process with a second
alkyne molecule, which would take place in a mono- or
bimetallic species. In this regard, it is worth mentioning that
recently Ritter and co-workers have found that free 10-
chlorobenzo[h]quinoline Clbzq is generated by oxidation of
[Pd(bzq)(OAc)]2 with PhICl2, and they have shown that the
reductive Cl−C bond elimination occurs via a dinuclear
symmetrical intermediate [Pd2III(bzq)2Cl2(OAc)2] complex.33
The structural details of 8 are those expected. Thus, the
Pt(1)−acetylide bond lengths [2.247(10), 2.223(9) Å] and the
bent back angles at Cα [160.4(9)°] and Cβ [155.4(10)°] are
comparable to those observed in [(OC)(C6F5)2Pt(μ-C
CPh)Pt(CCPh)(PPh3)2]34 [2.268(1), 2.257(10) Å;
165.0(9)°, 157.9(10)°], and as expected, the alkynyl vector is
essentially perpendicular to the Pt(1) coordination plane
[75.1(6)°]. The chelate (κN:η2-CC) bzqCCFc ligand is
whereas those of the η2-alkyne complexes 4−7 in CH2Cl2
solution are collected in Figure S7. For comparison, the
spectrum of Hbzq ligand is included in Figure 4. As is shown in
this figure, complexes 1−3 give intense absorptions (ε > 20 000
M−1 cm−1) in the range 243−370 nm, attributable to metal
perturbed π−π* intraligand (1IL, Hbzq, bzq, C6F5) transitions.
The cyclometalated complexes 1 and 3 exhibit two additional
and less intense (ε = 1.9−2.3 × 103 M−1 cm−1) low-energy
absorptions located at similar energies (397, 417 nm), which,
on the basis of theoretical calculations and previous assign-
ments, are attributed to an admixture of 1IL and metal-to-ligand
charge transfer (1MLCT).8c,e,35
As illustrated in Figure S7, coordination of the alkyne ligands
t
HCCR (R = Ph 4, Bu 5) and PhCCPh (7) causes only
minor modifications on the low energy region in relation to the
precursor 1. However, this band appears slightly shifted in the
tert-butyl alkyne derivative (406 nm) in relation to 4 and 7
(399 nm), containing the less donor phenyl and diphenylal-
kyne, suggesting some alkyne-to-bzq contribution. According
with theoretical calculations (TD-DFT) for complex [Pt(bzq)-
(C6F5)(η2-HCCPh)] 4, this band has mainly intraligand
1
character (1IL, bzq), with some metal-to-ligand MLCT and
ligand’-to-ligand (C6F5/alkyne→bzq) contribution. For the
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a
Table 2. Photophysical Data for Complexes 1−5 and 7
compd
medium (T/K)
λem/nm (λexc/nm)
τ/μs
[Pt(bzq)(C6F5)(acetone)] 1
solid (298)
solid (298)
solid (77)
480, 515, 585max (400)
∼595 (445−475)
506max, 540, 580sh (400)
482max, 507, 578sh (400)
477max, 514, 553, 598sh (490)
545 (400)
13.2 (480)
16.5 (585)
157
(2-Me)thf (298)
(2-Me)thf (77)
solid (298)
solid (77)
8.4
388
[Pt(C6F5)2(Hbzq)2] 2
9.1
508, 532max, 572sh (400)
570 (470)
341 (52%), 51.8 (48%) (532)
solid (77)
20.1
b
(2-Me)thf (77)
479max, 517, 554, 600sh (400)
496, 595max (400)
376
[Pt(bzq)(C6F5)(Hbzq)] 3
solid (298)
9.0 (495)
solid (298)
595 (450−480)
14.5
solid (77)
507max, 544, 586sh (400)
186
(2-Me)thf (298)
(2-Me)thf (77)
485max, 510 (400)
9.2
480max, 515, 555, 600sh (400)
609 (400−470)
510, 575max, 610 (380)
555sh, 575, 610 (440)
474 (370−440)
474max, 510, 550, 600sh (370−440)
600 (400−470)
481, 500max, 523, 538 (380)
481, 500max, 523, 538, 613max (440)
482 (370−440)
428
c
[Pt(bzq)(C6F5)(η2-HCCPh)] 4
[Pt(bzq)(C6F5)(η2-HCCtBu)] 5
[Pt(bzq)(C6F5)(η2-PhCCPh)] 7
solid (298)
12.8
solid (77)
solid (77)
167 (510)
112 (575); 65.2 (610)
d
CH2Cl2 (298)
10.0
d
CH2Cl2 (77)
342
c
solid (298)
13.9
solid (77)
solid (77)
76.9 (500)
42.8 (613)
11.3
e
CH2Cl2 (298)
e
CH2Cl2 (77)
479max, 515, 554, 600
565, 625max (400−470)
520max, 555 (400)
299
c
solid (298)
11.1 (565); 29.5 (23%), 5.0 (77%) (625)
41.7 (520); 42.1 (555); 47.9 (605)
solid (77)
solid (77)
555max, 605 (440)
e
CH2Cl2 (298)
482 (370−440)
478max, 512, 551, 600sh (370−440)
d
10.8
302
e
CH2Cl2 (77)
a
b
c
1−3, 10‑3 M; 4−7, 10‑4 M solutions. Not emissive at 298 K. Weak. In 2-Me(thf) solutions (298 K): 484max, 505 (370−440 nm); (77 K) 477max
,
e
512, 552, 600sh (370−440 nm). Similar pattern in 10‑4 M 2-Me(thf) solutions.
ferrocenyl alkyne complex 6, a similar band is also found at ca.
394 nm. As is typical in Fc containing complexes, this derivative
exhibits a lower and very weak energy band at 465 nm (ε ∼ 500
M−1cm−1) attributed, according to previous assignments,36 to a
1MLCT transition with some d−d character on the CCFc
group.
Emission Spectra. Complexes 1−3 exhibit luminescence in
the solid state and in solution at room temperature and at low
temperature (77 K) (Table 2). The cyclometalated complexes
1 and 3 show in solid state at 298 K an emission profile with
two different bands, related to different excitation profiles.
Upon excitation at 400 nm, they exhibit a long-lived high-
energy emission band (480, 515 nm 1, 496 nm 3), ascribed to a
3
typical mixed IL/3MLCT excited state, and a prominent low-
energy unstructured band centered at ∼595 nm, which can be
selectively obtained by increasing the wavelength of excitation
(Figure 5 for 3 and Figure S8 for 1). The shape and energy of
this low energy band, together with the presence of extended
close π···π (bzq) interactions observed in 3, are suggestive of
the occurrence of aggregation-induced π···π emission in solid
state, as has been supported by DFT calculations. Upon cooling
at 77 K, the emissions are more intense and turn visually into
green. The low-energy band disappears, showing only the
structured high emission band slightly red-shifted (506, 540,
580sh 1; 507, 544, 586sh nm 3), with long lifetimes (157 μs 1,
186 μs 3) indicative of emission having predominant 3IL
parentage. Probably, the access to the low energy aggregation-
induced ππ emission is less effective at 77 K than at 298 K,
Figure 5. Normalized excitation and emission spectra of [Pt(bzq)-
(C6F5)(acetone)] 3 in solid state at 298 and 77 K.
being responsible of the observed thermochromic behavior.
Both complexes (1 and 3) exhibit similar profiles in diluted (5
× 10−5 M) or concentrated (10−3 M) (2-Me)thf solutions (see
Table 2). They show at 298 K a slightly structured band in the
green region (∼500 nm) with lifetime measurements in the
microsecond range (8−9 μs), which becomes better structured
Figure S9) in glass state (77 K). The absence of rigid-
ochromism, together with the extremely long lifetimes (388 μs
1, 428 μs 3), which fit well to monoexponential decays (Figure
3
S10), are indicative of emission with primarily IL parentage.
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Complex [cis-Pt(C6F5)2(Hbzq)2] (2) exhibits in solid state at
298 K only a very weak emission (∼545 nm) of difficult
assignment, probably due to the lack of the cyclometalate
group. At 77 K (Figure S11), the intensity of the emission
increases, and two different bands, depending on the λexc used,
are observed. By excitation at λexc 400 nm, it shows a structured
emission band (508, 532 nm) with a long lifetime [341 (52%),
As was expected, in fluid CH2Cl2 at 298 K, all alkyne
complexes (4, 5, and 7) show an unstructured band (474 nm 4,
482 nm 5, 482 nm 7) with an emission lifetime in the
microsecond regime, which with reference to previous work in
benzoquinolate Pt(II) complexes,8a−e,h,11,12 is assigned to a
3
mixed IL/3MLCT excited state (Figure 7). At 77 K, the
3
51.8 (48%) μs] being attributed to a IL (Hbzq) excited state.
However, excitation at lower energies (λexc 470 nm) results in
an unstructured emission band centered at 570 nm, with a
shorter lifetime (20 μs). The excitation spectrum correspond-
ing to this 570 nm band (Figure S11) extends to ∼500 nm,
suggesting that this low energy emission could be likely
associated to the occurrence of close π···π interactions between
aromatic Hbzq ligands in solid state. In solution, complex 2 is
only emissive in glass state exhibiting a similar long-lived (376
3
μs) structured IL emission to that observed for 1 and 3.
With the exception of the ferrocenyl complex 6, the η2-alkyne
derivatives (4, 5, and 7) are also photoluminescent in solid state
and in solution at 298 and 77 K. The lack of luminescence in 6
is not unexpected and could be attributed to the presence of Fc
group, which deactivates the excited state through nonradiative
routes.37 Complexes 4 and 5 show in solid state at room
temperature a weak long-lived (12.8 μs 4, 13.9 μs 5) low-
energy emission (609 nm 4, 600 nm 5), likely dominated by an
excited state associated with the presence of a certain degree of
π···π intermolecular contacts, which usually shift to the red the
3
3
typical MLCT and/or LL′CT excited states (Figure S12).
Upon cooling to 77 K, this emission changes to a more intense
typical structured 3IL/3MLCT in 5 (500 nm, τ 76.9 μs),
whereas in 4 both emissions due to the monomer (minority,
510 nm, τ 167 μs) and π···π aggregation (majority, 575−605
nm, τ 65.2 μs) are still observed (see Figure S12). The solid
diphenylalkyne complex 7 exhibits at room temperature a broad
asymmetric emission, with two maxima at 565 nm (τ 11.1 μs)
and 625 nm [29.5 (33%), 5 (77%) μs], which clearly resolves
into two different structured emissions at 77 K. As can be seen
in Figure 6, these emissions are related with different excitation
profiles, suggesting the presence of two close nonequilibrated
Figure 7. Normalized emission spectra of (a) 4 and (b) 5 in CH2Cl2 5
× 10−4 M at 298 K and at 77 K.
3
excited states, tentatively attributed to mixed IL/3MLCT and
ligand′-to-ligand 3L′LCT (L′ = CC) excited states,
respectively.
emission band becomes vibronically resolved (λmax 474 4, 479
5, 478 nm 7). The very long lifetimes (∼300 μs) and the
negligible influence of the alkyne are indicative of a
predominant 3IL character (Figure 7). In (2-Me)thf fluid
solution, 4 reproduces exactly the spectrum observed for 1 thus
indicating, according also to the NMR data in d6-thf, that the
alkyne is substituted in solution by a solvent thf molecule,
whereas 5 and 7 are stable in thf solution, displaying a similar
profile to that described in CH2Cl2.
Theoretical Calculations. To gain further insight into the
nature of the absorption and emission characters of these
complexes in CH2Cl2 or (2-Me)thf a theoretical analysis based
on a DFT (TD-DFT) approach was performed on selected
complexes (3, 4, and 6). Structures (S0 and T1, Figures S13−
S15), geometrical details (Table S5), and optimized coor-
dinates (Table S6) are collected in the Supporting Information.
The optimized geometry of 3 reproduces the one obtained by
X-ray, including the dihedral angle between the Hbzq ligand
and the bzq plane and the short Pt···H(bzq) contact [2.39931
Å in S0, 2.39163 in T1 vs 2.4508(3) Å in X-ray]. For the alkyne
Figure 6. Normalized excitation and emission spectra of [Pt(bzq)-
(C6F5)(η2-PhCCPh)] (7) in solid state at 77 K.
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Table 3. Composition (%) of Frontier MOs in the Ground State for Complexes 3, 32, 4, and 6 in Gas Phase
3
32
MO
eV
C6F5
Hbzq
Pt
bzq
eV
C6F5
Hbzq
Pt
bzq
LUMO + 3
LUMO + 2
LUMO + 1
LUMO
−1.13
−1.54
−1.78
−1.99
−5.47
−5.78
−5.82
−6.04
0
0
1
98
0
3
1
96
1
−1.55
−1.56
−1.99
−2.00
−5.41
−5.42
−5.76
−5.77
0
0
0
0
0
0
4
4
42
2
2
2
56
96
0
0
3
97
0
100
100
2
0
0
99
1
1
0
0
HOMO
0
30
78
30
1
69
4
26
28
84
82
72
70
6
HOMO − 1
HOMO − 2
HOMO − 3
11
66
97
7
2
2
2
6
1
1
8
6
4
6
eV
C6F5
Pt
bzq
HCCPh
eV
C6F5
Pt
bzq
HCCFc
LUMO + 3
LUMO + 2
LUMO + 1
LUMO
−0.54
2
0
9
3
56
48
49
92
60
23
1
34
49
45
3
−0.53
−0.65
−1.42
−1.95
−5.49
−5.54
−5.85
−6.00
2
0
8
4
59
13
85
94
2
30
83
10
2
−1.17
−1.58
−1.98
−5.82
−6.0
0
5
0
5
1
4
0
4
HOMO
13
54
96
10
18
21
3
10
2
1
2
95
98
12
5
HOMO − 1
HOMO − 2
HOMO − 3
0
1
1
−6.17
−6.29
0
6
14
24
67
15
78
9
2
56
complexes 4 and 6, the expected perpendicular coordination of
the alkyne to the platinum coordination was obtained. In the
corresponding optimized T1 state of 4 the most remarkable
feature is the significant withdrawal of the Cβ carbon atom
(2.40791 in S0 to 3.21623 Å in T1).
values (485 nm (2Me)-thf 3, 482 nm CH2Cl2 4). As can be
seen in Figure 8 for complex 3, the LSOMO (HOMO in S0
The distribution of important frontier orbitals in the ground
state and the corresponding partial molecular orbital
composition (percentages), together with selected low-lying
transitions for 3, 4, and 6, are provided in Table 3 and in the
Supporting Information (Tables S7−S8). For complex 3, the
HOMO has mixed Pt and bzq character whereas the LUMO
and LUMO + 1, which are close in energy, are primarily located
in the Hbzq and bzq ligands, respectively. The lowest energy
singlet transition calculated in thf (390 nm) arises primarily
from HOMO to LUMO + 1, therefore, supporting a mixed
1MLCT (Pt→bzq)/1IL(bzq) character for the experimental
band located at 417 nm. Substitution of the Hbzq for the η2-
alkyne in 4 changes the nature of the LUMO (now located in
the bzq anion) and of the HOMO, which contains significant
contribution of the coligands (C6F5 13% and HCCPh 10%).
The lowest-energy band, experimentally observed in CH2Cl2 at
399 nm, is consistent with the simulated at 374 nm. This band,
which is blue-shifted in relation to 3 and primarily due to a
HOMO→LUMO transition, can be characterized as a mixed
1IL/1MLCT with some ligand(C6F5, alkyne)-to-ligand(bzq)
(1L′LCT) character.
Figure 8. Molecular orbital plots for the computed S0 and T1 states of
complex 3.
notation) is essentially analogous to the HOMO in the ground
state, being located on the bzq and the Pt. However, the
HSOMO (LUMO in S0 notation) has a different contribution
to the LUMO in the ground state, since after the triplet
optimization the unoccupied orbital centered on the bzq ligand
(LUMO + 1 in S0) is stabilized, becoming the HSOMO in T1.
Therefore, we conclude that the emission in complex 3 is due
to a 3IL excited state (L = bzq) with some mixing 3MLCT. For
4, the HSOMO and LSOMO orbitals in the optimized T1 state
are mainly centered on the bzq ligand (Figure S16, HSOMO =
bzq 83%, HCCPh 10%, Pt 7%; LSOMO = bzq 83%, HC
CPh 5%, Pt 12%) supporting an 3IL origin for its emission with
a negligible contribution of the alkyne unit.
In complex 6, with the η2-HCCFc ligand, the first
calculated allowed transition with strong oscillator strength is
blue-shifted (366 nm) in relation to 4, in agreement with that
observed experimentally (394 nm). This band mainly originates
from the HOMO − 2 to LUMO and can be also assigned as
1
1
mixture IL/1MLCT with L′LCT contribution.
We also investigated the emission properties by optimization
of the lowest-energy triplet state (T1) for complexes 3 and 4
using the unrestricted U-B3LYP method (Table S5, Figures
S13, S14). The calculated emission energies, as the difference
between the energy of the T1 and the energy of the singlet state
with the triplet state optimized geometry (544 nm thf 3, 504
nm CH2Cl2 4), are qualitatively close to the experimental
To interpret the low energy emissions observed in solid state
at room temperature not only for 3, but also for 1 and the
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alkyne derivatives, a DFT study was performed on a dimer 32
formed by two molecules of 3 stacked through the bzq ligands
as a model of the extended chain observed in the crystal
structure. On the basis of calculations (Table S6, Figure S17),
we found that the frontier molecular orbitals (HSOMO and
LSOMO) in the optimized T1 state are delocalized over the
two bzq ligands and the metal centers, having some degree of
π···π bonding interaction (Figure S18). This fact is suggestive
of stronger π···π interaction in the excited state, which is
reflected in the shorter bzq···bzq separation in T1 in relation to
the ground state (see Table S9) and may be considered as the
major cause for the substantial stabilization of the emitting
state. This phenomenon has many precedents in square-planar
Pt(II) complexes and recently has been also observed in
phosphorescent Ir(III) complexes.38 The room temperature
solid-state emission can be ascribed to aggregation induced
emission having strong platinum-to-ligand-ligand charge trans-
fer (3MLLCT).
EXPERIMENTAL SECTION
■
General Comments. All reactions were carried out under an
atmosphere of dry argon, using standard Schlenk techniques. Solvents
were obtained from a solvent purification system (M-BRAUN MB
SPS-800). NMR spectra were recorded at 293 K on Bruker ARX 300
or ARX 400 spectrometers. Chemical shifts are reported in ppm
relative to external standards (SiMe4, CFCl3), and all coupling
constants are given in Hz. The NMR spectral assignments of the
benzoquinolate ligand (bzq) follow the numbering scheme shown in
Figures S1 and S3. IR spectra were obtained on a Nicolet Nexus FT-IR
spectrometer, using nujol mulls between polyethylene sheets.
Elemental analyses were carried out with Perkin-Elmer 2400
CHNS/O or Carlo Erba EA1110 CHNS-O microanalyzers. Mass
spectra were recorded on a HP-5989B (ES) or a Microflex MALDI-
TOF Bruker (MALDI) spectrometer operating in the linear and
reflector modes using dithranol as matrix. The optical absorption
spectra were recorded using a Hewlett-Packard 8453 (solution)
spectrophotometer in the visible and near-UV ranges. Emission and
excitation spectra were obtained on a Jobin-Yvon Horiba Fluorolog 3-
11 Tau-3 spectrofluorimeter, with the lifetimes measured in
phosphorimeter mode. 7,8-Benzoquinolate (Hbzq) was purchased
from Sigma-Aldrich, and [cis-Pt(C6F5)2(thf)2] was prepared as
reported previously.39
CONCLUSIONS
■
In summary, an interesting platinum solvate complex [Pt(bzq)-
(C6F5)(acetone)] 1 has been prepared by easy C−H activation
of Hbzq using [cis-Pt(C6F5)2(thf)2] as precursor. We have
found that the metalation involves the initial formation of the
saturated complex [cis-Pt(C6F5)2(Hbzq)2] 2, which subse-
quently reacts with additional [cis-Pt(C6F5)2(thf)2] to give 1
and C6F5H. Moreover, the isolation of 2 allows us to illustrate
that the metalation on the electrophilic “cis-Pt(C6F5)2”
fragment is very effective as this complex evolves easily to the
new derivative [Pt(bzq)(C6F5)(Hbzq)], 3.
Preparation of [Pt(bzq)(C6F5)(CH3COCH3)] (1). 7,8-Benzoquinoline
0.16 g (0.89 mmol) was added to an acetone solution (20 mL) of [cis-
Pt(C6F5)2(thf)2] (0.60 g, 0.89 mmol) and the mixture refluxed for 2.5
h. Then, the resulting yellow solution was evaporated to small volume
(∼2 mL) and treated with 15 mL of n-hexane, to yield complex 1 as a
1
microcrystalline yellow product (0.52 g, 97%). H NMR (400 MHz,
CD3COCD3, 20 °C, δ): 8.67 (d, J ≈ 8, H2, bzq), 8.66 (d, J ≈ 8, H4,
bzq) (two overlapped signals), 7.87 (d), 7.79 (d) (J = 8.6, H5/H6,
bzq), 7.75 (t, J ≈ 7, H3, bzq), 7.58 (d, J = 7.5, H7, bzq), 7.26 (t, J = 7.4,
3
H8, bzq), 6.90 (d, J = 6.9, JPt−H = 70, H9, bzq), 2.06 (s, 6H,
CH3COCH3). 19F NMR (282.5 MHz, CDCl3, δ): −40 °C, −118.4
3
(dd, JPt−F = 513, 2o-F), −161.6 (t, p-F), −163.3 (m, 2m-F); 20 °C,
On the other hand, we have shown that the acetone molecule
in 1 can be easily displaced by alkynes allowing the synthesis of
[Pt(bzq)(C6F5)(η2-RCCR′)] (4−7), which are the first
reported η2-alkyne-cycloplatinate complexes. The isolation of
the terminal η2-alkyne derivatives 4−6 is particularly rare, and
their stability in relation to typical vinylidene isomers was
addressed by DFT calculations in 4 and [Pt(bzq)(C6F5)(
CCHPh)] 4′. These η2-alkyne complexes are only
moderately stable in nondonor solvents, and in the case of 6,
it was found to evolve to the diplatinum complex [Pt(κN:η2-
bzq-C≡CFc)(C6F5)(μ-κCα:η2-C≡CFc)Pt(bzq)(C6F5)] (8)
containing the unusual κN-η2-bzqCCFc ligand. Further,
studies aimed at generating functionalized benzoquinoline
derivatives starting from 6 are in progress.
All complexes (except 6) showed emissive properties in
solution and glasses that originated mainly from intraligand
(bzq) excited states with some mixing 3MLCT, as supported by
TD-DFT on selected complexes. Complexes 1 and 3 exhibit an
interesting luminescent thermochromism in the solid state.
This behavior has been rationalized (DFT calculations) in
terms of the occurrence of aggregation induced emission,
favored by intermolecular π···π stacking of adjacent bzq ligands,
as supported by the crystal structure of 3. At low temperature,
both complexes (1, 3) display the typical structured green
emission due to admixture 3IL/3MLCT excited states,
associated with essentially undisturbed monomer species. The
orange emission observed at room temperature is associated
with the participation of a low-lying emissive state, which
delocalizes the electron density onto both adjacent bzq ligands
[platinum ligand-to-ligand charge transfer (3MLLCT) in
nature].
3
−118.1 (d, JPt−F = 501, 2o-F), −162.2 (t, p-F), −164.0 (m, 2m-F).
13C{1H} NMR (100.6 MHz, CD3COCD3, 20 °C, δ): 206.8 (s, CO,
CH3COCH3), 155.3 (s, JPt−C = 108, C12), 151.7 (dm, J = 228, C6F5),
148.3 (s, C2), 142.8 (s, C10), 139.9 (s, C4), 138.5 (dm, C6F5), 135.4 (s,
3JPt−C = 42, C14), 135.3 (s, 2JPt−C = 126, C9), 131.0 (s, C5 or C6), 130.9
(s, 3JPt−C = 89, C8); 129.2 (s, C11), 128.5 (s, 3JPt−C = 25, C13), 125.1 (s,
C5 or C6), 123.8 (s, C3), 123.2 (s, C7), 31.6 (s, CH3, CH3COCH3). IR
(cm−1): ν(CO) 1661(s), νx‑sens(C6F5) 802 (s). MS ES(−): m/z (%)
599 [M]−, (17); 540 [M − (CH3COCH3)]− (5). Anal. Calcd (%) for
C22F5H14NOPt: C, 44.16; H, 2.36; N, 2.34. Found: C, 43.91; H, 2.29;
N, 2.01%.
Preparation of [cis-Pt(C6F5)2(Hbzq)2] (2). To a cooled (−40 °C)
dichloromethane (5 mL) solution of [cis-Pt(C6F5)2(thf)2] (0.075 g,
0.11 mmol) was added 2 equiv of 7,8-benzoquinoline (Hbzq) (0.040
g, 0.22 mmol). After 5 min the solvent was removed from the resulting
yellow solution and the residue treated with n-hexane to give 2 as a
1
yellow solid (0.040 g, 41%). H NMR (300 MHz, CDCl3, 20 °C, δ):
12.16 (d, J = 8.3, 2H, H10′), 8.83 (d, J = 4.5, JPt−H ≈ 27, 2H, H2′),
3
7.98 (t, J = 7.3, 2H), 7.73 (t, J = 6.9, 2H), 7.65 (d, J = 7.7, 2H), 7.40
(m, 4H), 6.99 (d, J = 8.7, 2H), 6.44 (m, 2H). 19F NMR (282.5 MHz,
CDCl3, δ): −40 °C, −119.4 (d, 3JPt−F = 390, 2o-F), −119.7 (d, 3JPt−F
=
484, 2o-F), −161.6 (t, 2p-F), −163.3 (m, 2m-F), −164.2 (m, 2m-F);
3
20 °C, −119.6 (m, br, JPt−F ≈ 430, 4o-F), −162.2 (t, 2p-F), −164.5
(m, 4m-F). IR (cm−1): νx‑sens(C6F5) 795 (m), 806 (m). MS ES(−): m/
z (%) 707 [Pt(bzq)(C6F5)2]− (100). Anal. Calcd (%) for
C38F10H18N2Pt: C, 51.42; H, 2.04; N, 3.16. Found: C, 51.07; H,
2.06; N, 3.09%.
Preparation of [Pt(bzq)(C6F5)(Hbzq)] (3). Hbzq (0.023 g, 0.13
mmol) was added to a dichloromethane (5 mL) solution of
[Pt(bzq)(C6F5)(CH3COCH3)], 1, (0.075 g, 0.13 mmol) at 0 °C.
The mixture was stirred for 5 min, and the solvent was removed.
Treatment of the residue with n-hexane yielded 3 as a yellow solid
(0.070 g, 75%). 1H NMR (300 MHz, CDCl3, 20 °C, δ): 12.44 (d, J =
6.8, H10′, Hbzq), 10.14 (d, J = 4.6, H2′, Hbzq), 8.42 (d, J = 7.7, H4′,
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Hbzq), 8.22 (d, J = 8.0, H2, bzq), 7.91 (m, 2H), 7.79 (m, 2H), 7.77−
7.60 (m, 5H, with H9′ signal at δ 7.71, and H3′ signal at δ 7.68), 7.41
(t, J = 7.5, 1H), 7.25 (m, 1H), 7.11 (m, 2H). 19F NMR (282.5 MHz,
[M]+ (53%). Anal. Calcd (%) for C33H18F5NPt: C, 55.16; H, 2.52; N,
1.95. Found: C, 54.96; H, 2.33; N, 2.01%.
Computational Details for Theoretical Calculations. DFT
calculations were performed on complexes 3, 4, 4′, 6, and the dimer 32
with Gaussian 03 (revision E.01).40 Geometries in the S0 ground state
were optimized using the B3LYP method for all complexes and in the
T1 excited state for complexes 3, 32, and 4 using the unrestricted U-
B3LYP (T1) Becke’s three-parameter functional combined with Lee−
Yang−Parr’s correlation functional.41 No negative frequency was
found in the vibrational frequency analysis. 32 was optimized starting
from a dimer obtained by the π···π interactions in the X-ray diffraction
study of complex 3. The basis set used for the platinum centers was
the LanL2DZ effective core potential42 and 6-31G(d,p) for the ligand
atoms. The solvent effect of the tetrahydrofuran or dichloromethane in
the TD-DFT calculations was taken in consideration by the polarizable
continuum model (PCM).43
3
3
CDCl3, 20 °C, δ): −116.1 (d, JPt−F = 469, o-F), −120.2 (d, JPt−F
=
489, o-F), −163.5 (t, p-F), −164.5 (m, m-F), −165.0 (m, m-F).
13C{1H} NMR (100.6 MHz, CDCl3, −40 °C, δ): 154.9 (s, C2′, Hbzq),
153.9 (s), 153.8 (s), 149.0 (dm, C6F5), 146.1 (s), 145.5 (s), 142.0 (s,
C10, bzq), 139.2 (s, C4′, Hbzq), 137.7 (s, C2, bzq), 136.8 (dm, C6F5),
134.9 (s), 134.2 (s), 134.1 (s), 134.0 (s), 130.1(s), 129.9 (s), 129.8 (s),
129.7 (s), 128.6 (s), 128.5 (s), 127.7 (s), 127.2 (s, C10′, Hbzq), 126.8
(s), 125.9 (s), 123.4 (s), 122.4 (s), 122.3 (s, C3′, Hbzq), 121.8 (s,
bzq). IR (cm−1): νx‑sens(C6F5) 797 (m). MS ES(−): m/z (%) 540 [M
− (Hbzq)]− (19). Anal. Calcd (%) for C32F5H17N2Pt: C, 53.41; H,
2.38; N, 3.89. Found: C, 53.63; H, 2.54; N, 3.52%.
t
Synthesis of [Pt(bzq)(C6F5)(HCCR)] (R = Ph 4, Bu 5, Fc 6).
To a solution of [Pt(bzq)(C6F5)(CH3COCH3)], 1, (0.130 g, 0.217
mmol) in CH2Cl2 (∼ 20 mL) was added the corresponding alkyne
(0.217 mmol) and the mixture stirred for 30 min. Then the solvent
was removed under vacuum and the residue treated with Et2O (5 mL)
to give the products as yellow (4 and 5) or orange (6) solids.
X-ray Crystallography. Details of the structural analyses for
complex 3 and 8 are summarized in Table 4. Pale yellow (3) or orange
Table 4. Crystallographic Data for 3·0.25CH2Cl2 and
8·2.5CH2Cl2·H2O
1
Data for [Pt(bzq)(C6F5)(HCCPh)] (4). Yield (0.098 g, 70%). H
NMR (CDCl3, 20 °C, δ): 8.66 (d, 3JH−H = 4.9 Hz, 1H, bzq), 8.32 (d,
3
3JH−H = 7.9 Hz, 1H, bzq), 7.91 (d, JH−H = 7.4 Hz, 1H, bzq), 7.81 (d,
empirical formula
C32.5Cl0.5H17.5F5N2Pt
740.80
C64.5Cl5H41F10Fe2N2OPt2
1729.17
3
3JH−H = 8.7 Hz, 1H, bzq), 7.69 (d, JH−H = 7.8 Hz, 1H, bzq), 7.58 (d,
Fw
3
3JH−H = 8.7 Hz, 1H, bzq), 7.50 (t, JH−H = 9.1 Hz, 1H, bzq), 7.48 (t,
T (K)
173(1)
123(1)
3JH−H = 7.6 Hz, 1H, bzq), 7.40−7.22 (m, Ph), 7.15 (s, Ph), 7.13 (s,
Ph), 4.91 (s, JPt−H = 46 Hz, 1H, HCCPh). 19F NMR (282.4 MHz,
CDCl3, 20 °C, δ): −118.7 (d, JPt‑oF = 450 Hz, 2o-F), −162.3 (t, 1p-F),
−164.0 (m, 2m-F). IR(cm−1): ν(C−H) 3233 (s), ν(CC) 1985
(m), ν(C6F5)X‑sens 802 (m). MALDI-TOF (−): m/z 641 [M − H]−
(28%). Anal. Calcd (%) for C27H14F5NPt: C, 50.47; H, 2.20; N, 2.18.
Found: C, 50.06; H, 1.88; N, 1.98%.
cryst syst; space group triclinic; P1
triclinic; P1
̅
̅
a (Å); α (deg)
b (Å); β (deg)
c (Å); γ (deg)
V (Å3); Z
8.1679(7); 71.521(4) 13.4380(8); 108.519(3)
12.3058(9); 84.253(5) 14.3390(9); 91.022(4)
14.3251(7); 84.989(3) 14.4630(9); 93.348(3)
1356.39(17); 2
1.814
2636.1(3); 2
2.178
Dcalcd (Mg/m3)
abs coeff (mm−1
F(000)
)
5.281
5.908
1
Data for [Pt(bzq)(C6F5)(HCCtBu)] (5). Yield (0.058 g, 43%). H
713
1436
3
NMR (400 MHz, CDCl3, 20 °C, δ): 8.81 (d, J = 4.4, JPt−H = 45, H2,
cryst size (mm2)
0.20 × 0.20 × 0.20
2.97−25.68
0.20 × 0.10 × 0.05
1.49−26.37
bzq), 8.39 (d, J = 7.6, H4, bzq), 7.83 (d, J = 8.4, H6, bzq), 7.70 (d, J ≈
8, H7, bzq), 7.61 (m, H3/H5, bzq), 7.51 (t, J = 7.2, H8, bzq), 7.18 (d, J
= 7.2, 3JPt−H = 82, H9, bzq), 4.15 (s, JPt−H = 50, 1H, HCCtBu), 1.33
θ range for data
collection (deg)
index ranges
0 ≤ h ≤9
−16 ≤ h ≤16
−17 ≤ k ≤16
0 ≤ l ≤18
t
(s, 9H, Bu). 19F NMR (282.4 MHz, CDCl3, 20 °C, δ): −115.2 (d,
−14 ≤ k ≤15
−17 ≤ l ≤17
5092/4/386
JPt‑oF = 448, o-F), −120.8 (d, JPt‑oF = 445, o-F), −162.5 (t, 1p-F),
−164.0 (m, m-F), −164.6 (m, m-F). 13C{1H} NMR (100.62 MHz,
CDCl3, 20 °C, δ): 143.7 (s, bzq), 137.7 (s, bzq), 133.7 (s, bzq), 129.2
(s, bzq), 124.4 (s, bzq), 122.6 (s, bzq), 120.9 (s, bzq), 120.8 (s, bzq),
95.1 (s, CCR), 65.7 (s, H-C), 30.5 (s, C(CH3)3), 30.2 (s,
C(CH3)3). IR(cm−1): ν(C−H) 3253, 3245 (s); ν(CC) 1974
(m), ν(C6F5)X‑sens 802 (s). MALDI-TOF (+): 620 [M]+ (8%). Anal.
Calcd (%) for C25H18F5NPt: C, 48.24; H, 2.91; N, 2.25. Found: C,
47.98; H, 2.83; N, 2.01%.
no. data/restraints/
params
10 712/0/614
a
GOF on F2
1.094
1.046
final R indexes [I >
R1 = 0.0444, wR2 =
0.1151
R1 = 0.0511, wR2 = 0.1252
a
2σ(I)]
a
R indices (all data)
R1 = 0.0476, wR2 =
0.1176
R1 = 0.0765, wR2 = 0.1330
largest diff peak and
4.643 and −1.939
1.641 and −2.013
1
hole (e Å−3
)
Data for [Pt(bzq)(C6F5)(HCCFc)] (6). Yield (0.105 g, 65%). H
NMR (400 MHz, CDCl3, 20 °C, δ): 8.67 (d, J = 5.2, 3JPt−H ≈ 25, H2,
bzq), 8.33 (d, J ≈ 8, H4, bzq), 7.81 (d, J = 8.8, H6, bzq), 7.68 (d, J ≈
a
2
R1 = Σ(|Fo| − |Fc|)/Σ|Fo|; wR2 = [Σw(Fo2 − Fc2)2/ΣwFo ] 1/2; GOF =
{Σ[w(Fo2 − Fc2)2]/(Nobs − Nparam)}1/2; w = [σ2(Fo) + (g1P)2 + g2P]−1;
7.6, H7, bzq), 7.58 (d, J = 8.4, H5, bzq), 7.51 (m, H3/H8, bzq), 7.15 (d,
P = [max(Fo ; 0 + 2Fc2]/3.
2
3
J = 7.2, JPt−H = 68, H9, bzq), 4.77 (s, 2H, C5H4, Fc), 4.47 (s, JPt−H
=
F
48, 1H, HCCFc), 4.28 (s, 2H, C5H4, Fc), 4.08 (s, 5H, Cp, Fc). 19
NMR (282.4 MHz, CDCl3, 20 °C, δ): −117.9 (d, JPt‑oF = 462, 2o-F),
−162.2 (t, 1p-F), −164.0 (m, 2m-F). IR(cm−1): ν(C−H) 3215 (s),
ν(CC) 1996 (m), ν(C6F5)X‑sens 809 (m). MALDI-TOF (+): 750
[M]+ (8%). Anal. Calcd (%) for C31H18F5FeNPt: C, 49.62; H, 2.42; N,
1.87. Found: C, 49.48; H, 2.36; N, 1.53%.
(8) crystals were obtained by slow diffusion at −30 °C of n-hexane
into solutions of the complexes in CH2Cl2. X-ray intensity data were
collected with a NONIUS-κCCD area-detector diffractometer, using
graphite-monochromated Mo Kα radiation, and the images were
processed using the DENZO and SCALEPACK suite of programs,44
carrying out the absorption correction at this point for complex 3. For
complex 8, the absorption correction was performed using
SORTAV.45 The structures were solved by Direct and Patterson
Methods using SIR200446 (3) or DIRDIF9647 (8), and refined by full-
matrix least-squares on F2 with SHELXL-97.48 All non-hydrogen
atoms were assigned anisotropic displacement parameters. All the
hydrogen atoms were constrained to idealized geometries fixing
isotropic displacement parameters 1.2 times the Uiso value of their
attached carbon. For both structures, the correct assignment of the
position of the C and N atoms bonded to platinum in the
benzoquinolate ligand was confirmed by examination of the
Synthesis of [Pt(bzq)(C6F5)(PhCCPh)] (7). Compound 7 was
prepared as a yellow solid following the same procedure as for 4 using
[Pt(bzq)(C6F5)(CH3COCH3)] (0.150 g, 0.250 mmol) and PhC
1
CPh (0.046 g, 0.250 mmol) (0.163 g, 90%). H NMR (400 MHz,
3
CDCl3, 20 °C, δ): 8.58 (d, J = 4.4, JPt−H = 26, H2, bzq), 8.34 (d, J =
8.8, H4, bzq), 7.95 (d, J = 6.8, 4H, o-Ph), 7.87 (d, J = 8.4, H6, bzq),
7.80 (d, J ≈ 8, H7, bzq), 7.64 (d, J ≈ 6, H5, bzq), 7.58 (m, H8, bzq),
3
7.42 (m, H3, bzq), 7.37−7.30 (6H, m,p-Ph), 7.19 (d, J = 7.6, JPt−H
=
66, H9, bzq). 19F NMR (282.4 MHz, CDCl3, 20 °C, δ): −117.0 (dm,
JPt‑oF = 426, 2o-F), −162.7 (t, 1p-F), −164.4 (m, 2m-F). IR(cm−1):
ν(CC) 2017 (m), ν(C6F5)X‑sens 802 (m). MALDI-TOF (+): 718
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ΔMSDA values for bonds involving these atoms,49 after refining each
case in three different ways (with the identities of the C and N in one
position, reversed, and with 50/50 hybrid scattering factor at each of
the affected atomic sites). For complex 3, 0.5 molecules of disordered
crystallization CH2Cl2 were found in the unit cell, and four restraints
were used in order to model them. For complex 8, disordered
crystallization molecules of CH2Cl2 and H2O were also observed.
Despite many attempts, we could not resolve the disorders adequately.
The use of SQUEEZE50 revealed the presence in the unit cell of one
central void of 301 Å3 containing 212 electrons, which fits well with
the presence five molecules of CH2Cl2, and two little voids of 15 Å3
containing one water molecule each of them (11 electrons). Therefore,
we have included them in the empirical formula as crystallization
solvent (8·2.5CHCl3·H2O). Finally, both structures show some
residual peaks greater than 1 e Å−3 in the vicinity of the platinum
atoms or the crystallization solvent, but with no chemical meaning.
Coord. Chem. Rev. 2011, 255, 2426. (l) Wong, K. M. C.; Yam, V. W.
W. Acc. Chem. Res. 2011, 44, 424. (m) Zhou, K. J.; Wong, W. Y. Chem.
Soc. Rev. 2011, 40, 2541. (n) Cummings, S. D. Coord. Chem. Rev. 2009,
253, 449.
(3) (a) Yang, C.; Zhang, X.; You, H.; Zhu, L.; Chen, L.; Zhu, L.; Tao,
Y.; Ma, D.; Shuai, Z.; Quin, J. Adv. Funct. Mater. 2007, 17, 651.
(b) Cocchi, M.; Virgili, D.; Fattori, V.; Rochester, D. L.; Williams, J. A.
G. Adv. Funct. Mater. 2007, 17, 285. (c) Chen, C. H.; Wu, F. L.; Tsai,
Y. Y.; Cheng, C. H. Adv. Funct. Mater. 2011, 21, 3150. (d) Yang, X.;
Wang, Z.; Madakuni, S.; Li, J.; Jabbour, G. E. Adv. Mater. 2008, 20,
2405. (e) Kui, S. C. F.; Hung, F. F.; Lai, S. L.; Yuen, M. Y.; Kwok, C.
C.; Low, K. H.; Chui, S. S. Y.; Che, C. M. Chem.Eur. J. 2012, 18, 96.
(f) Ma, B.; Djurovich, P. I.; Garon, S.; Allyne, B.; Thompson, M. E.
Adv. Funct. Mater. 2006, 16, 2438.
(4) (a) Koo, C. K.; So, L. K. Y.; Wong, K. L.; Ho, Y. M.; Lam, Y. W.;
Lam, M. H. W.; Cheah, K. W.; Cheng, C. C. W.; Kwok, W. M.
Chem.Eur. J. 2010, 16, 3942. (b) Yam, V. W. W.; Tang, R. P. L.;
Wong, K. M. C.; Lu, X. X.; Cheung, K. K.; Zhu, N. Chem.Eur. J.
2002, 8, 4066. (c) Ma, D. L.; Che, C. M.; Yan, S. C. J. Am. Chem. Soc.
2009, 131, 1835. (d) Wu, P.; Wong, E. L. M.; Ma, D. L.; Tong, G. S.
M.; Ng, K. M.; Che, C. M. Chem.Eur. J. 2009, 15, 3652. (e) Lusby,
ASSOCIATED CONTENT
* Supporting Information
■
S
Additional figures and tables. Complete reference for Gaussian
03 (revision E.01). This material is available free of charge via
the Internet at http://pubs.acs.org.
P. J.; Muller, P.; Pine, S. J.; Slawin, A. M. Z. J. Am. Chem. Soc. 2009,
̈
131, 16398. (f) Zhao, Q.; Li, F. Y.; Huang, C. H. Chem. Soc. Rev. 2010,
39, 3007. (g) Zhao, Q.; Li, F. Y.; Huang, C. H. Chem. Soc. Rev. 2011,
40, 2508.
AUTHOR INFORMATION
Corresponding Author
*Fax: (+34) 941 299 621. E-mail: elena.lalinde@unirioja.es.
■
(5) (a) Shavaleev, N. M.; Adams, H.; Best, J.; Edge, R.; Navaratnam,
S.; Weinstein, J. Inorg. Chem. 2006, 45, 9410. (b) Zhang, J.; Du, P.;
Schneider, J.; Jarosz, P.; Eisenberg, R. J. Am. Chem. Soc. 2007, 129,
7726.
Notes
The authors declare no competing financial interest.
(6) (a) Hissler, M.; McGarrah, J. E.; Connick, W. B.; Geiger, D. K.;
Cummings, S. D.; Eisenberg, R. Coord. Chem. Rev. 2000, 208, 115.
(b) Tong, G. S. M.; Che, C. M. Chem.Eur. J. 2009, 15, 7225.
(7) (a) Brooks, J.; Babayan, Y.; Lamanski, S.; Djurovich, P. I.; Tsyba,
I.; Bau, R.; Thompson, M. E. Inorg. Chem. 2002, 41, 3055. (b) Ghedini,
M.; Pugliese, T.; La Deda, M.; Goldbert, N.; Aiello, I.; Amati, M.;
Belviso, S.; Leli, F.; Accorsi, G.; Barigelletti, F. Dalton Trans. 2008,
4303. (c) Mou, X.; Wu, Y.; Liu, S.; Shi, M.; Liu, X.; Wang, C.; Sun, S.;
Zhao, Q.; Zhou, X.; Huang, W. J. Mater. Chem. 2011, 21, 13951.
(d) Wu, W.; Guo, H.; Wu, W.; Ji, S.; Zhao, J. Inorg. Chem. 2011, 50,
11446.
ACKNOWLEDGMENTS
■
This work was supported by the Spanish MICINN (Project
CTQ2008-06669-C02-02/BQU) and by the CAR (Colabora
2009/05). S.S. thanks CSIC for a grant. The authors also thank
CESGA for computer support.
DEDICATION
■
†Dedicated to Professor Juan Fornies
́
on the occasion of his
65th birthday.
(8) (a) Fernan
Dalton Trans. 2003, 822. (b) Díez, A.; Fornies
E.; Moreno, M. T. Inorg. Chem. 2005, 44, 2443. (c) Díez, A.; Fornies
J.; Fuertes, S.; Lalinde, E.; Larraz, C.; Lopez, J. A.; Martín, A.; Moreno,
M. T.; Sicilia, V. Organometallics 2009, 28, 1705. (d) Fornies, J.;
Fuertes, S.; Lopez, J. A.; Martín, A.; Sicilia, V. Inorg. Chem. 2008, 47,
7166. (e) Díez, A.; Fornies, J.; Larraz, C.; Lalinde, E.; Lopez, J. A.;
́
dez, S.; Fornies
́
, J.; Gil, B.; Gom
́
ez, J.; Lalinde, E.
́
, J.; García, A.; Lalinde,
REFERENCES
́
,
■
́
(1) (a) Special issue: Controlling Photophysical Properties of Metal
Complexes: Towards Molecular Photonics. Coord. Chem. Rev. Vlcek,
́
̌
́
T., Guest Ed.; 2011, 255 (21−22), 2399. (b) Guerchais, V.;
Ordronneau, L.; Le Bozec, H. Coord. Chem. Rev. 2010, 254, 2553.
(c) Chen, Z. N.; Zhao, N.; Fan, Y.; Ni, J. Coord. Chem. Rev. 2009, 253,
1. (d) Photofunctional Transition Metal Complexes. Structure and
Bonding; Yam, V. W. W., Ed. Springer: Berlin, 2007; Vol. 123. (e) Lai,
S. W.; Che, C. M. Top. Curr. Chem. 2004, 241, 27. (f) Rausch, A. F.;
Homeier, H. H. H.; Yersin, H. Top. Curr. Organomet. Chem. 2010, 29,
193. (g) Djurovich, P. I.; Thompson, M. E. In Highly Efficient OLEDs
with Phosphorescent Materials; Yersin, H., Ed.; Wiley-VCH: Weinheim,
2008; p 131. (h) Xiang, H. F.; Lai, S. W.; Lai, P. T.; Che, C. M. In
Highly Efficient OLEDs with Phosphorescent Materials; Yersin, H., Ed.;
Wiley-VCH: Weinheim, Germany, 2007; p 259. (i) Evans, R. C.;
Douglas, P.; Winscom, C. Coord. Chem. Rev. 2006, 250, 2093.
(2) (a) Williams, J. A. G. Top. Curr. Chem. 2007, 281, 205.
(b) Williams, J. A. G. Chem. Soc. Rev. 2009, 38, 1783. (c) Williams, J.
A. G.; Develay, S.; Rochester, D. L.; Murphy, L. Coord. Chem. Rev.
2008, 252, 2596. (d) Eryazici, I.; Moorefield, C. N.; Newkome, G. R.
Chem. Rev. 2008, 108, 1834. (e) Berenguer, J. R.; Lalinde, E.; Moreno,
M. T. Coord. Chem. Rev. 2010, 254, 832. (f) Murphy, L.; Williams, J. A.
G. Top. Organomet. Chem. 2010, 28, 75. (g) Chi, Y.; Chou, P. T. Chem.
Soc. Rev. 2010, 39, 638. (h) Wong, K. M. C.; Yam, V. W. W. Coord.
Chem. Rev. 2007, 251, 2477. (i) Wong, W. Y. Dalton Trans. 2007,
4495. (j) McGuire, R., Jr.; McGuire, M. C.; McMillin, D. R. Coord.
Chem. Rev. 2010, 254, 2574. (k) Díez, A.; Lalinde, E.; Moreno, M. T.
́
́
Martín, A.; Moreno, M. T.; Sicilia, V. Inorg. Chem. 2010, 49, 3239.
(f) Rausch, A. F.; Monkowins, U. V.; Zabel, M.; Yersin, H. Inorg.
Chem. 2010, 49, 7818. (g) Liu, J.; Sun, R. W. Y.; Leung, C. H.; Lok, C.
N.; Che, C. M. Chem. Commun. 2012, 48, 230. (h) Zheng, G. Y.;
Rillema, D. P.; DePriest, J.; Woods, C. Inorg. Chem. 1998, 37, 3588.
(9) (a) Yagyu, T.; Ohashi, J. I.; Maeda, M. Organometallics 2007, 26,
2383. (b) Calvet, T.; Crespo, M.; Font-Bardia, M.; Gom
́
ez, K.;
Gonzalez, G.; Martínez, M. Organometallics 2009, 28, 5096. (c) Jamali,
́
S.; Nabavizadeh, S. M.; Rashidi, M. Inorg. Chem. 2008, 47, 5441.
(d) Zucca, A.; Cinellu, M. A.; Minguetti, G.; Stoccoro, S.; Monassero,
M. Eur. J. Inorg. Chem. 2004, 4484. (e) Minguetti, G.; Doppin, A.;
Zucca, A.; Stoccoro, S.; Cinellu, M. A.; Manassero, M.; Sansoni, M.
Chem. Heterocycl. Cmpd. 1999, 35, 992. (f) Martín, R.; Crespo, M.;
Font-Bardia, M.; Calvet, T. Organometallics 2009, 28, 587. (g) Crespo,
M.; Font-Bardia, M.; Calvet, T. Dalton Trans. 2011, 40, 9431.
(h) Zhao, S. B.; Wang, R. Y.; Wang, S. J. Am. Chem. Soc. 2007, 129,
3092. (i) Nabavizadeh, S. M.; Haghighi, M. G.; Esmaeilbeig, A. R.;
Raoof, F.; Mandegani, Z.; Jamali, S.; Rashidi, M.; Puddephatt, R. J.
Organometallics 2010, 29, 4893. (j) Haghighi, M. G.; Rashidi, M.;
Nabavizadeh, S. M.; Jamali, S.; Puddephatt, R. J. Dalton Trans. 2010,
39, 11396. (k) Rao, Y. L.; Wang, S. Inorg. Chem. 2009, 48, 7698.
(l) Nabavizadeh, S. M.; Amini, H.; Shahsavari, H. R.; Namdar, M.;
11677
dx.doi.org/10.1021/ic301563u | Inorg. Chem. 2012, 51, 11665−11679

Inorganic Chemistry
Article
Rashidi, M.; Kia, R.; Hemmateenjad, B.; Nekoeinia, M.; Ariafard, A.;
Hosseini, F. N.; Ghavari, A.; Khalafi-Nezhad, A.; Sharbati, M. T.;
Panahi, F. Organometallics 2011, 30, 1466.
(10) (a) Crespo, M. Organometallics 2012, 31, 1216. (b) Canty, A. J.
Dalton Trans. 2009, 10409. (c) Albrecht, M.; van Koten, G. Angew.
Chem., Int. Ed. 2001, 40, 3750.
M.; Falvello, L. R.; Fornies
1997, 1559.
(24) (a) Konig, A.; Bette, M.; Wagner, C.; Linder, R.; Steinborn, D.
́
, J.; Martín, A. J. Chem. Soc., Dalton Trans.
̈
Organometallics 2011, 30, 5919. (b) Uson
Menjon, B.; Fortuno, C.; Welch, A. J.; Smith, D. E. J. Chem. Soc.,
Dalton Trans. 1993, 275. (c) Uson
Menjon, B.; Welch, A. J. J. Organomet. Chem. 1986, 304, C24.
́ ́ ́
, R.; Fornies, J.; Tomas, M.;
́
̃
́
́ ́
, R.; Fornies, J.; Tomas, M.;
́
(11) Fornies
M. T. Organometallics 2004, 23, 3963.
(12) (a) Fornies, J.; Ibanez, S.; Martín, A.; Sanz, M.; Berenguer, J. R.;
Lalinde, E.; Torroba, J. Organometallics 2006, 25, 4331. (b) Fornies
Ibanez, S.; Lalinde, E.; Martín, A.; Moreno, M. T.; Tsipis, A. C. Dalton
́
, J.; Ibanez, S.; Martín, A.; Gil, B.; Lalinde, E.; Moreno,
́
̃
(d) Tanabe, M.; Osakada, K. Chem.Eur. J. 2004, 10, 416. (e) Huber,
C.; Bangerter, F.; Caseri, W. R.; Weder, C. J. Am. Chem. Soc. 2001,
123, 3857.
́
́
̃
́
, J.;
(25) (a) Yam, V. W. W.; Lo, K. K. W.; Wong, K. M. C. J. Organomet.
́
̃
́
Chem. 1999, 578, 3. (b) Fornies, J.; Lalinde, E. J. Chem. Soc., Dalton
Trans. 2012, 3439.
Trans. 1996, 2587. (c) Wong, K. M. C.; Lam, W. H.; Zhou, Z. Y.; Yam,
V. W. W. Chem.Eur. J. 2008, 14, 10928.
(13) (a) Steinborn, D.; Tschoerner, M.; von Zweidorf, A.; Sieler, J.;
Bogel, H. Inorg. Chim. Acta 1995, 234, 47. (b) Gerisch, M.;
̈
(26) Marinelli, G.; Streib, W. E.; Huffman, J. C.; Gagne, M. R.;
Takats, J.; Dartiguenave, M.; Chardon, C.; Jackson, S. A.; Einsteins, O.
Polyhedron 1990, 9, 1867.
Heinemann, F. W.; Bogel, H.; Steinborn, D. J. Organomet. Chem.
̈
1997, 548, 247. (c) Fanizzi, F. P.; Natile, G.; Lanfranchi, M.;
Tiripicchio, A.; Pacchioni, G. Inorg. Chim. Acta 1998, 275−276, 500.
(d) Engelman, K. L.; White, P. S.; Templeton, J. L. Inorg. Chim. Acta
2009, 362, 4461. (e) Clark, H. C.; Manzer, L. E. Inorg. Chem. 1974, 13,
1291.
(27) (a) Carlisle, S.; Matta, A.; Valles, H.; Bracken, J. B.; Miranda,
M.; Yoo, J.; Hahn, C. Organometallics 2011, 30, 6446 and references
therein. (b) Cucciolito, M. E.; de Renzi, A.; Roviello, G.; Ruffo, F.
Organometallics 2008, 27, 1351. (c) West, N. M.; White, P. S.;
Templeton, J. L. Organometallics 2008, 27, 5252. (d) Sagawa, T.;
Sakamoto, Y.; Tanaka, R.; Katayama, H.; Ozawa, F. Organometallics
2003, 22, 4433. (e) Lucey, D. W.; Atwood, J. D. Organometallics 2002,
21, 2481. (f) Appleton, T. G.; Clark, H. C.; Puddephatt, R. J. Inorg.
Chem. 1972, 11, 2074.
(28) (a) Belluco, U.; Bertani, R.; Fornasiero, S.; Michelin, R. A.;
Mozzon, M. Inorg. Chim. Acta 1998, 275−276, 515. (b) Belluco, U.;
Bertani, R.; Michelin, R. A.; Mozzon, M.; Benetollo, F.; Bomberi, G.;
Angelici, R. J. Inorg. Chim. Acta 1995, 240, 567. (c) Cucciolitto, M. E.;
De Felice, V.; Orabona, I.; Ruffo, F. J. Chem. Soc., Dalton Trans. 1997,
1351. (d) Clark, H. C.; Manzer, L. E. J. Am. Chem. Soc. 1973, 95, 3812.
(29) (a) Nordhoff, K.; Steinborn, D. Organometallics 2001, 20, 1408.
(b) Karonik, M.; Lesage, D.; Gimbert, Y.; Nava, P.; Humbel, S.;
Giordanos, L.; Buono, G.; Tabet, J. C. Organometallics 2011, 30, 4814.
(30) Belluco, U.; Bertani, R.; Meneghetti, F.; Michelin, R. A.;
Mozzon, M. J. Organomet. Chem. 1999, 583, 131.
́
(14) (a) Fornies, J.; Lalinde, E. In Comprehensive Organometallic
Chemistry III; Crabtree, R. H., Mingos, D. M. P., Eds.; Elsevier:
Oxford, 2007; Vol 8. p 611. (b) Young, G. B. In Comprehensive
Organometallic Chemistry; Abel, E. W., Stone, F. G. A., Wilkinson, G.,
Elsevier: Oxford, 1995; Vol. 9, p 553. (c) Belluco, U.; Bertani, R.;
Michelin, R. A.; Mozzon, M. J. Organomet. Chem. 2000, 600, 37.
(15) (a) Albrecht, M. Chem. Rev. 2010, 110, 576 and references
therein. (b) Omay, I. Coord. Chem. Rev. 2004, 248, 995.
(c) Steenwinkel, P.; Gossage, R. A.; van Koten, G. Chem.Eur. J.
1998, 4, 759. (d) Ryabov, A. D. Chem. Rev. 1990, 90, 403. (e) Dupont,
J.; Consorti, C. S.; Spencer, J. Chem. Rev. 2005, 105, 2527. (f) Niu, J.
L.; Hao, X. Q.; Gong, J. F.; Song, M. P. Dalton Trans. 2011, 40, 5135.
(g) Canty, A. J. Acc. Chem. Res. 1992, 25, 83. (h) Rendina, L. M.;
Puddephatt, R. J. Chem. Rev. 1997, 97, 1735.
(16) Cope, A. C.; Siekman, R. W. J. Am. Chem. Soc. 1965, 87, 3272.
(17) (a) Zucca, A.; Cordeschi, D.; Stoccoro, S.; Cinellu, M. A.;
Minguetti, G.; Chelucci, G.; Manassero, M. Organometallics 2011, 30,
3064. (b) Zucca, A.; Petretto, G. L.; Cabras, M. L.; Stoccoro, S.;
Cinellu, M. A.; Manassero, M.; Minghetti, G. J. Organomet. Chem.
2009, 694, 3753. (c) Zucca, A.; Petretto, G. L.; Stoccoro, S.; Cinellu,
M. A.; Manassero, M.; Manassero, C.; Minguetti, G. Organometallics
2009, 28, 2150. (d) Minguetti, G.; Stoccoro, S.; Cinellu, M. A.;
Petretto, G. L.; Zucca, A. Organometallics 2008, 27, 3415. (e) Zucca,
A.; Petretto, G. L.; Stoccoro, S.; Cinellu, M. A.; Minghetti, G.;
Manassero, M.; Manassero, C.; Male, L.; Albinati, A. Organometallics
2006, 25, 2253. (f) Crosby, S. H.; Clarkson, G. J.; Rourke, J. P.
Organometallics 2011, 30, 3603.
(31) Berenguer, J. R.; Fornies
Organometallics 1995, 14, 2532.
́
, J.; Lalinde, E.; Martínez, F.
(32) Modern Acetylene Chemistry; Stang, P. J., Diederich, F., Eds.;
VCH: Weinheim, Germany, 1995.
(33) (a) Powers, D. C.; Geibel, M. A. L.; Klein, J. E. M. N.; Ritter, T.
J. Am. Chem. Soc. 2009, 131, 17050. (b) Powers, D. C.; Benítez, D.;
Tkatchouk, E.; Goddard, W. A., III; Ritter, T. J. Am. Chem. Soc. 2010,
132, 14092.
(34) Berenguer, J. R.; Fornies, J.; Lalinde, E.; Martínez, F.;
́
Urriolabeitia, E.; Welch, A. J. Dalton Trans. 1994, 1291.
(35) Berenguer, J. R.; Díez, A.; Lalinde, E.; Moreno, M. T.; Ruiz, S.;
Sanchez, S. Organometallics 2011, 30, 5776.
́
(18) Fornies
1992, 11, 1187.
́ ́ ́ ́
, J.; Menjon, B.; Gomez, N.; Tomas, M. Organometallics
(36) (a) Bhadbhade, M. M.; Das, A.; Jeffery, J. C.; McCleverty, J. A.;
Navas Badiola., J. A.; Ward, M. D. J. Chem. Soc., Dalton Trans. 1995,
2769. (b) Barlow, S.; Bunting, H. E.; Ringham, C.; Green, J. C.;
Bublitz, G. U.; Boxer, S. G.; Perry, J. W.; Marder, S. R. J. Am. Chem.
(19) (a) Vicente, J.; Arcas, A.; Bautista, D.; Jones, P. G.
Organometallics 1997, 16, 2127. (b) Vicente, J.; Arcas, A.; Galvez-
Lop
M.; Fornies
26, 1674.
́
ez, M. D.; Jones, P. G. Organometallics 2006, 25, 4247. (c) Casas, J.
́
, J.; Fuertes, S.; Martín, A.; Sicilia, V. Organometallics 2007,
Soc. 1999, 3715. (c) Díez, A.; Fernan
́
dez, J.; Lalinde, E.; Moreno, M.
T.; Sanchez, S. Dalton Trans. 2008, 4926.
́
(20) Alsters, P. L.; Engel, P. F.; Hogerheide, M. P.; Copijn, M.; Spek,
A. L.; van Koten, G. Organometallics 1993, 12, 1831.
(37) (a) Lee, E. J.; Wrighton, M. S. J. Am. Chem. Soc. 1991, 113,
8562. (b) Fery-Forgues, S.; Delavaux-Nicot, B. J. Photochem. Photobiol.,
A 2000, 132, 137. (c) Fery-Forgues, S.; Delavaux-Nicot, B.; Lavabre,
D.; Rurack, K. J. Photochem. Photobiol., A 2003, 155, 107.
(38) Zhao, Q.; Li, L.; Li, F.; Yu, M.; Liu, Z.; Yi, T.; Huang, C. Chem.
Commun. 2008, 685.
(21) As previously suggested, the C−H bond activation could take
place through an oxidative addition leading to a pentacoordinated
Pt(IV) hydride intermediate. The final cyclometalated 1 will be formed
by a subsequent fast reductive elimination of the hydride and the C6F5
group and coordination of the acetone solvent. Unfortunately, we have
not detected any intermediate hydride complex, and therefore, its
implication in the pathway leading to 1 is only speculative.
(22) Albinati, A.; Pregosin, P. S.; Wombacher, F. Inorg. Chem. 1990,
29, 1812.
(39) Uson
1985, 4, 1912.
́ ́ ́ ́
, R.; Fornies, J.; Tomas, M.; Menjon, B. Organometallics
(40) Frisch, M. J.; et al. Gaussian 03, Revision E.01: Gaussian, Inc.:
Wallingford, CT, 2004 (see the Supporting Information for the
complete citation).
(23) (a) Chatterjee, S.; Krause, J. A.; Madduma-Liyanage, K.;
Connick, W. B. Inorg. Chem. 2012, 51, 4572. (b) Casas, J. M.; Falvello,
L. R.; Fornies, J.; Martín, A. Inorg. Chem. 1996, 35, 6009. (c) Casas, J.
́
(41) (a) Becke, A. D. Phys. Rev. A 1988, 38, 3098. (b) Becke, A. D. J.
Chem. Phys. 1993, 98, 5648. (c) Lee, C.; Yang, W.; Parr, R. G. Phys.
Rev. B 1988, 37, 785.
11678
dx.doi.org/10.1021/ic301563u | Inorg. Chem. 2012, 51, 11665−11679

Inorganic Chemistry
Article
(42) Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284.
(43) Barone, V.; Cossi, M. J. Phys. Chem. A 1998, 102, 1995.
(44) Otwinosky, Z.; Minor, W. In Methods Enzymology; Carter Jr., C.
V., Sweet, R. M., Eds.; Academic Press:: New York, 1997; Vol. 276A, p
307.
(45) Blessing, R. H. Acta Crystallogr. 1995, A51, 33.
(46) Burla, M. C.; Caliandro, R.; Carrozzini, B.; Cascarano, G. L.; De
Caro, L.; Giacovazzo, C.; Polidori, G.; Spagna, R. J. Appl. Crystallogr.
2005, 38, 381.
(47) Beurskens, P. T.; Beurskens, G.; Bosman, W. P.; de Gelder, R.;
Garcia-Granda, S.; Gould, R. O.; Israel, R.; Smits, J. DIRDIF96
Program System; M. M. Crystallography Laboratory University of
Nijmegen: The Netherlands, 1996.
(48) Sheldrick, G. M. SHELX-97, A Program for the Refinement of
Crystal Structures; University of Gottingen: Gottingen, Germany, 1997.
̈
̈
(49) (a) Speck, A. L. Acta Crystallogr., Sect. A. 1990, 46, c34.
(b) Hirshfeld, F. L. Acta Crystalogr., Sect. A. 1976, 32, 239.
(50) Spek, A. L. SQUEEZE, Incorporated into PLATON: A
Multipurpose Crystallographic Tool; University of Utrecht: Utrecht,
The Netherlands, 2005.
11679
dx.doi.org/10.1021/ic301563u | Inorg. Chem. 2012, 51, 11665−11679