Biscyclometalated platinum complexes with thiophene ligands

Article abstract of DOI:10.1016/j.jorganchem.2012.10.027

The reaction of [Pt₂(CH₃)₄(μ-S(CH ₃)₂)₂] with four equivalents of ligand C ₄H₃SCHNCH₂C₆H₅ gives the platinum (II) complex [Pt{(C₄

Full text of DOI:10.1016/j.jorganchem.2012.10.027

Journal of Organometallic Chemistry 723 (2013) 188e197
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Journal of Organometallic Chemistry
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Biscyclometalated platinum complexes with thiophene ligands
a
,
a
a
,
b
a
a
*
Craig M. Anderson , Michael A. Weinstein , James Morris , Nicole Kfoury , Leila Duman ,
a
a
a
a
a
Tedros A. Balema , Ava Kreider-Mueller , Perry Scheetz , Skylar Ferrara , Matteo Chierchia ,
c
Joseph M. Tanski
a
Department of Chemistry, Bard College, 30 Campus Rd, Annandale-on-Hudson, NY 12504, USA
Department of Chemistry, University of Rochester, Rochester, NY, USA
Department of Chemistry, Vassar College, 124 Raymond Avenue, Box 601, Poughkeepsie, NY 12604, USA
b
c
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 August 2012
Received in revised form
3 4 3 2 2 4 3 2 6 5
The reaction of [Pt (CH ) (m-S(CH ) ) ] with four equivalents of ligand C H SCH]NCH C H gives the platinum
ˇ
2
(
II) complex [Pt{(C
can also be prepared by refluxing the monometalated species [Pt(C
toluene or with the addition of one equivalent of ligand C SCH]NCH
for [Pt (CH -S(CH ] with the ligands (S)-C SCH]NCHCH
4
H
2
S)CH]NCH
2
C
6
H
5
}
2
] with two cyclometalated C N ligands. [Pt{(C
SCH]NCH
. Similar reactions were observed
and C SCH]NC , and the cor-
4
H
2
2 6 5 2
S)CH]NCH C H } ]
H
4 2
2
C
6
H
5
)CH (S(CH )], alone in
3
3 2
)
13 October 2012
H
4 3
2 6 5
C H
Accepted 15 October 2012
2
3
)
4
(m
3
)
2
)
2
H
4 3
C H
3 6 5
H
4 3
6 5
H
responding monocyclometalated species. A mechanism of formation is proposed with the support of DFT
calculations. The complexes show emission, in solution, at room temperature, with emission bands red-shifted
Keywords:
Cyclometalation
Platinum
Thiophene
Emission
DFT
w200 nm, excited state lifetimes of the order of 1
were used to assist in the assignment of the electronic spectroscopy.
Ó 2012 Elsevier B.V. All rights reserved.
ms, and modest quantum yields up to 0.012. DFT calculations
1. Introduction
followed by subsequent reductive elimination of methane with no
prior activation of ligands.
CeH activation is an important area of research and the subject
of much recent work in several areas of chemistry, including
organometallic chemistry, catalytic chemistry, and bioinorganic
chemistry [1e12,47]. The activation and selective functionalization
of CeH bonds for industrial and synthetic purposes is a rich area of
research [13e20]. Over the past several years we have synthesized
a number of organometallic, cyclometalated complexes by CeH or
CeX bond activation [21e23], as cyclometalated compounds and
polypyridyl compounds, due to their interesting and rich photo-
physical properties, have applications in many areas, including,
OLEDs, catalysts, solar energy conversion, molecular switches,
molecular devices, and sensors [24e35]. Interest in such compounds
stretches into bioinorganic applications as well [36,37]. Furthermore,
thiophene-transition metal complexes have been studied for the
important reason of understanding the process of hydro-
desulfurization [38e41]. Here we describe the synthesis of biscy-
clometalated, thiophene, platinum compounds that emit at room
temperature. Interestingly, the complexes may be synthesized in
several straightforward ways by CeH activation/oxidative addition
2
. Results and discussion
2.1. Synthesis
Imine ligands
NCHCH , 5a, (Chart 1) were prepared from the condensation
reactions of the appropriate primary amine and the appropriate
aldehyde as previously reported [42,43]. 4a, C SCH]NC , and
a, C SCH]NCH , which have not beenpreviously reported,
were prepared similarly. When four equivalents of 3a, 4a, and 5a,
were allowed to react with the platinum dimer, [Pt (CH
S(CH ] [44], 1, in refluxing toluene (Scheme 1), the complexes
C
4 3 2 6 5 4 3
H SCH]NCH C H , 3a and (S)-C H SCH]
3 6 5
C H
4
H
3
6 5
H
7
H
4 3
2 10 7
C H
2
3 4
) (m-
3 2 2
) )
with two cyclometalated ligands, 3c, 4c, and 5c, (Chart 1) were
formed. The new complexes were characterized by their NMR, IR,
UV/vis, emission spectra, quantum yields, excited state lifetimes,
elemental analyses, as well as by high-resolution mass spectrometry
(HRMS). The compounds 4b and 4c were characterized by X-ray
diffraction, XRD, (see below) and, in the case of 3c, a low quality XRD
study was conducted that was only good enough to indicate the
connectivity of atoms, which showed a structure to be consistent
with our spectroscopic data. In all cases the complexes are square
*
Corresponding author. Tel.: þ1 845 752 2356; fax: þ1 845 752 2339.
E-mail address: canderso@bard.edu (C.M. Anderson).
0
022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.10.027

C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
189
4:1 with
[
Pt (S(CH ) ) (CH ) ]
2 3 2 2 3 2
R
R
N
N
R
S
Pt
N
S
N
S
Pt
S
R
3 2
S(CH )
2
:1 with
H
3
C
]
i. 1:1 w/ligand, toluene
OR
ii. toluene, reflux
3
5
b: R=H
b: R=CH3
3
5
a: R=H
[Pt (S(CH
2
3
)
2
)
2
(CH
3
)
2
3c: R=H
5c: R=CH
a: R=CH3
3
N
Pt
N
N
S
S
N
S
Pt
2
:1 with
S
S(CH
3
)
2
i. 1:1 w/ligand, toluene
OR
[
Pt (S(CH ) ) (CH ) ]
3
H C
2
3 2 2
3 2
ii. toluene, reflux
4:1 with
[
Pt (S(CH ) ) (CH ) ]
2
3 2 2
3 2
Scheme 1. Synthesis of Complexes.
planar with the carbon donors of each chelate ligand trans to the
imine nitrogen of the other chelate ligand.
The NMR spectra are very helpful in the characterization of the
complexes. In the case of 3c, the imine proton is observed at
reported [45] and forms easily under mild conditions. 7b was formed
analogously to 6b. We can speculate that steric hindrance in the
transition state may be the relevant variable in the formation of the
products involving a sacrificial platinum complex, as we propose
a bimetallic intermediate in order to facilitate the transfer of the
second ligand to the first metal center (see below and Scheme 2). 3c
has the least amount of steric crowding (Chart 1), as it has a small
methylene group between the thiophene ring and the dangling
phenyl ring off of the imine. 5c has an additional methyl group in
between the two rings, while 7c has a dangling naphthyl instead of
the phenyl group. 6c would have had both the methyl in the spacer
group and a dangling naphthyl, which leads us to speculate that the
steric hindrance precludes any reaction to afford product in this case.
4c has no methylene spacer and only a phenyl group directly
attached to the thiophene ring; therefore, it is somewhat structurally
different and more rigid than the others and is not included in this
direct comparison. Cyclometalated ligands are usually very rigid and
7
4
(
.98 ppm with Pt satellites of 70 Hz and the methylene protons at
.70 ppm with Pt satellites of 12 Hz, all characteristic of platinum
II) cyclometalated species. All of our complexes have similar
spectra and their peaks are in the same range as similar structures
23]. All bismetalated (mono and bis refer to the number of rings
[
formed by CeH activation with a platinum center) compounds
were analyzed using a high-resolution quadrupole time of flight
mass spectrometer. In all cases, the observed m/z of the predomi-
þ
nant [M þ H] ion agreed with the exact mass of the predicted
molecular formula within 3 ppm. The isotope distribution observed
for each compound agrees with the isotope pattern predicted,
further confirming that the compounds have the molecular formula
reported.
One interesting point about the synthesis of these compounds is
that the compounds can be made by three different methods. The
most straightforward is the method mentioned above where four
equivalents of ligand are allowed to react with the platinum
dimethyl precursor. The second method involves the reaction of the
monometalated species, 3b, 4b, or 5b, (Chart 1) with one equivalent
of ligand (Scheme 1) in refluxing toluene. The third method, in our
opinion the most interesting, is to reflux the monometalated species
somewhat inert. The complexes with two such ligands are much
more inert than the complexes with only one C N ligand, as can be
ˇ
observed from their lack of reactivity in refluxing toluene and they
are also relatively unreactive for several days at room temperature in
common solvents. The biscyclometalated compounds reported here
are formed as a straightforward manner as a direct result of oxidative
addition of the appropriate CeH bond followed by a subsequent
reductive elimination of methane and are more easily prepared and
purified than the previously reported thienylpyridine complexes,
which do not have an imine functionality, were orthometalated at
the 3-position of the thiophene ring, and required lithiation of the
ligands to activate them in order to obtain the bismetalated products
[46]. Therefore our synthesis allows for a direct reaction and elimi-
nates the need of extra halogenation/lithiation steps.
(Scheme 1) in toluene with no additional ligand. This third method
produces the final bismetalated product in small yields, is accom-
panied by decomposition of some starting monocyclometalated
material, and must involve a sacrificial platinum complex in order
that the final complex include the second cyclometalated ligand
(Scheme 1). It appears that 3c, using the third method, is formed
under more mild conditions (as determined by the time of reflux
needed to complete the reaction) than 5c, which in turn, is formed
under more mild conditions than 7c, which was never obtained in
pure form because of excessive decomposition. 7c was obtained only
by the third method, not the other two methods, and only in
miniscule amounts. However, 7c was partially characterized by NMR
and HRMS, as it was the major product of the impure mixture. 6c
DFT studies at the B3LYP/LANL2DZ level were preformed on all
intermediates for a proposed pathway for the formation of 3c
(Scheme 2a and b). The Gaussian03 suite of programs was used to
do all calculations. The reaction path has two possible routes, one
involving bimetallic intermediates and another that involves single
metal intermediates. Scheme 2a and b lists the energies of the
intermediates along the reaction coordinate for both the bimetallic
route and the route when an additional equivalent of ligand is
added to the system, respectively (see Scheme 1 for overall details).
All reported structures were optimized to ground states as
(
S.I.), a target compound with two cyclometalated (R)-C
NCHCH ligands [45], was not obtained under any reaction
conditions attempted. The monometalated species, 6b, has been
4 3
H SCH]
3 10 7
C H

190
C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
Chart 1. : Structure of ligands and complexes. Compound 7c was not obtained in pure form.
confirmed by frequency analysis of each structure. All thermody-
namic values appear reasonable given the required experimental
reaction conditions. Although transition states have not been
located along the entire route for each path, much information can
be gained by ground state calculations of suspected intermediates
conformations of the bimetallic species were reasonable multiple
conformations were energy optimized and each found the same
lowest energy structure. That is, the geometry (Fig. 1) is for the
minimum in which the sulfur of the thiophene ring is directed
toward what would otherwise be a vacant site at platinum. The
energy of this conformation is lower than that of any in which the
[2,47]. Either mechanism is plausible given the energy of the
intermediates and the reaction conditions used to make the bis-
metalated products.
sulfur is pointed away from the metal center. In this case, without
additional ligand, we would not expect both ends of the C N chelate
ˇ
In the case of the reaction without free ligand, where a sacrificial
metal compound is needed, we hypothesize that the intermediate
is bimetallic with the sulfur of the thiophene ring being loosely
coordinated to the platinum (Fig. 1) [47] thus stabilizing the
molecule. The structure C5 depicted in Fig. 1 is that of an optimized
ground state. Furthermore, in order to test whether the
ligand to dissociate from one metal center completely and then
subsequently attack the second platinum center. We note that the
calculations for loss of dimethylsulfide are favored compared to
dissociation of the imine nitrogen, thus favoring an entry into our
proposed mechanism for bismetalation. On a separate note, the
ˇ
equilibrium between the starting material (C N)PtMe(S(CH
3
)
2
) and

C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
Ph
191
a
N
S
S
CH
3
CH
3
CH
3
-
3 2
S(CH )
Pt
Pt
S
Pt
N
N
3 2
S(CH )
3 2
S(CH )
H= +14.4
G= 2.9
Gtoluene= 11.8
Ph
Ph
H= +26.2
G= +24.2
C-1
C-2
Gtoluene=+20.8
Ph
N
S
CH
3
CH3
H= -22.3
G= -13.1
Gtoluene= -9.1
for HSol=water
H= -21.4
Pt
Pt
N
N
G= -22.1
Gtoluene= -28.2
for HSol=water
Ph
HSol
(
H
3
C)
2
S
S
C-1 + C-2
N
Ph
Ph
H= -2.2
G= +8.3
Gtoluene= +6.2
Pt
H= +30.5
H= -15.1
G= -4.3
(H
C)
2
S
Pt
3
S
G= +30.9
3
H C
CH
3
S
Gtoluene=+33.0
for HSol=toluene
Gtoluene= -18.6
for HSol=toluene
C-6
C-5
HSol=toluene, water
S
CH
3
S
H= -19.4
G= - 19.2
Gtoluene= -30.9
for Sol=OH
Pt
N
CH
3
S
S
1
) Ox Add
Pt
Ph
2
) Red Elim
N
N
Pt
N
Sol
Pt
Ph
Ph
H
N
H= -4.7
G= -18.3
Gtoluene= -4.6
2
for Sol=CH Ph
H= -19.72
(
H
3
C)
2
S
N
Ph
Ph
Ph
G= -30.04
S
Gtoluene= -22.3
CH
3
C-7
Sol=CH
S
2
Ph, OH
C-8
All units are in kcal/mol and are the deltaH or deltaG reaction for the indicated step as gas phase.
Gtoluene also includes a pcm solvent model with toluene as solvent.
b
S
CH
3
Pt
N
2
H O
Ph
2
C-1H O
H= -0.9
+
H2O
G=-3.72
-
S(CH
3
)
2
Gtoluene=-1.0
Ph
N
S
S
CH
3
CH
3
CH
3
-
3 2
S(CH )
Pt
Pt
S
Pt
N
N
3 2
S(CH )
S(CH
3 2
)
H= +14.4
G= 2.9
Gtoluene= 11.8
Ph
Ph
H= +26.2
G= +24.2
Gtoluene=+20.8
C-1
C-2
S
CH
3
S
S
Ph
Pt
N
1) Ox Add
) Red Elim
N
N
2
C-2 +
Ph
Pt
H=-26.02
N
N
G= -12.45
Ph
H= -19.72
Ph
Ph
Gtoluene=-15.60
G= -30.04
S
Gtoluene= -22.3
S
C-8
All units are in kcal mol and are the deltaH or deltaG reaction for the indicated step as gas phase.
Gtoluene also includes a pcm solvent model with toluene as solvent.
Scheme 2. a: Proposed bimetallic, bismetalation mechanism. b: Proposed reaction mechanism with additional ligand added.

192
C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
2.2. Structures of complexes 4b and 4c
Suitable crystals of [C
6
H
5
NC SPt(S(CH ) )CH ], 4b, were
5
H
3
3 2 3
grown by the vial-in-a-vial technique with slow diffusion of
pentane into an acetone solution. The crystal structure is composed
of discrete molecules separated by van der Waals interactions. No
pi-stacking or intermolecular interactions were found. Selected
bond lengths and angles are given in Table 1a and a molecular view
is shown in Fig. 2a. The compound consists of a square planar
platinum (II) center bonded to one cyclometalated 4a ligand,
a methyl group, and a dimethylsulfide ligand. Bond lengths and
angles are in the expected range for analogous compounds
4 2 6 5 2
[23,45,46]. Suitable crystals of [Pt((C H S)CH]N(C H )) ], 4c, were
grown by slow evaporation of acetone. The crystal structure is
composed of discrete molecules separated by van der Waals inter-
actions. No pi-stacking or intermolecular interactions were found.
However the two dangling phenyl rings have an intramolecular pi-
stacking interaction. Selected bond lengths and angles are given in
Table 1b and a molecular view is shown in Fig. 2b. The compound
consists of a square planar platinum (II) center bonded to two
identical 4a ligands. Each cyclometalated ligand in each structure
behaves as a [C,N]-bidentate and a five-membered chelate ring is
formed in each case, fused with the thiophene moiety, as five-
membered metallacycle rings are quite common [22]. The imine
N donor atom of each ligand is trans to a carbon donor atom; methyl
in the case of 4b and a carbon of the thiophene ring of the second
ligand for 4c, which agrees with our NMR data. The five-membered
rings are relatively planar. The angles between adjacent atoms in
ꢀ
the coordination sphere of platinum lie in the range 78e104 , with
ꢀ
the N(1)ePteN(2) angle of 4c being the largest at 103.7(1) . This is
Fig. 1. Molecule C5 (see Scheme 2a) showing close contact between thiophene sulfur
and platinum. Close contact distance is calculated as 2.77 A in optimized structure.
Starting an energy optimization from other conformations show that the molecule will
approach the depicted structure.
probably due to the crowding caused by the pendant phenyl rings.
c has no methylene spacer between the metallacycle and the
4
dangling phenyl group, unlike many of our earlier reported struc-
tures. However, bond lengths and angles are in the expected range
for analogous compounds [23,45,46]. In all cases, the stereochem-
istry at the C]N is necessarily trans. The metallacycle is approxi-
mately planar and coplanar with the thiophene ring.
ˇ
(
C N)PtMe(H
2
O) is essentially thermoneutral (Hrxn ¼ 0.9 kcal/mol),
very slightly favoring water coordination at platinum. Given the
above, adventitious water in the solvent may provide the hydrogen
source for the elimination of the ligand from the platinum
(C6 through C8). Since the equilibrium seems viable, it is reasonable
3. Absorption and emission spectroscopy
to consider the reaction of C1 and C2 to make the dinuclear species,
which, as stated above, our calculations suggest is stabilized by
sulfur from thiophene coordinating at the ‘vacant site’ of the three
coordinate species C2. Finally, refluxing the monometalated species
in toluene would certainly give enough thermal energy to drive all
reactions as written. An alternative mechanism involving a simple
transmetalation is also possible. Several calculations were run to
obtain thermodynamic data for a variety of transmetalation reac-
tions (Scheme SI-1) and in all cases the reactions were close to
thermoneutral in the gas phase. When solvent correction was
added the free energy increased, slightly disfavoring the formation
of the initial products, as written in the scheme, for all cases.
However, these reactions had platinum metal precipitation asso-
ciated with them therefore the products listed in the schemes are
most likely not the final decomposition products. Hence the fate of
the second platinum atom and other ligands is not explicitly known
but can only be labeled as “unidentifiable decomposition products”.
No compound in the crude reaction mixtures other than starting
material or product could be definitively assigned.
The absorption spectra of ligands 3a, 4a, and 5a were recorded
and the compounds do not absorb in the visible region. Numerical
data for all absorption and emission spectra is given in Table 2.
3a and 5a have very similar spectra (see S.I.) whereas 4a’s
spectrum has its peaks red-shifted by approximately 30 nm. The
ligands show no emission at 300 K when excited at their lowest
energy peak. The absorbance spectra of the monocyclometalated
complexes 3b, 4b, and 5b are shown in Fig. 3. They show several
bands in the UV/vis range with the lowest energy bands at 420 nm
for 3b and 5b, and 435 nm for 4b. All three compounds emit in the
visible when excited at these wavelengths (Fig. 4). The emission
spectra of 3b and 4b are very similar. They are broad and have
a maximum at approximately 610 nm. 5b’s spectrum is slightly
different with a peak at 650 nm and a shoulder at 575 nm.
Table 1a
ꢀ
ꢀ
Selected bond lengths (A) and angles ( ) with estimated standard deviations for
compounds 4b.
In the case where additional ligand has been added or is avail-
able, the reaction may certainly proceed as outlined in Scheme 2b,
where the imine nitrogen of the second ligand coordinates to the
platinum after the dimethylsulfide has dissociated. The reaction
would then continue with oxidative addition of the CeH bond of
the thiophene followed by reductive elimination of methane, two
well-known reactions.
Pt(1)eC(1)
Pt(1)eN(1)
S(2)eC(12)
C(1)ePt(1)eC(14)
C(14)ePt(1)eN(1)
C(14)ePt(1)eS(2)
C(1)eS(1)eC(2)
1.9719(18)
2.1662(15)
1.797(2)
93.93(8)
170.71(7)
92.47(6)
Pt(1)eC(14)
Pt(1)eS(2)
S(2)eC(13)
C(1)ePt(1)eN(1)
C(1)ePt(1)eS(2)
N(1)ePt(1)eS(2)
C(12)eS(2)eC(13)
2.0447(19)
2.3416(5)
1.800(2)
78.20(7)
171.12(6)
94.86(4)
94.21(9)
98.52(11)

C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
193
in monocyclometalated compounds. This increase indicates that
the biscyclometalated complexes are not just two discrete ligands
bound to one metal center and indicates that these peaks are
probably not intraligand bands. Since the ligands themselves do not
absorb in the visible and the extinction coefficients for these bis-
cyclometalated complexes in the 400e440 nm range are on the
a
3
ꢁ1
ꢁ1
order of 10 (M
cm ), we tentatively assign the absorbance
peaks as charge transfer bands. These bands have traditionally been
assigned [46,48e50] as MLCT, but more recent reports [29,33], in
conjunction with computational studies (see below), would have us
assign these transitions as mixed metaleligand to ligand charge
transfer (MM-LLCT). In addition, these biscyclometalated
complexes have a much less intense absorbance peak at lower
energy, with 4c’s being the most pronounced at 530 nm. This peak
at lower energy is assigned to the direct excitation to the triplet
state similar to the biscyclometalated complexes recently reported
[33]. TDDFTcalculations predict such a peak to occur at 543 nm. The
bismetalated complexes are clearly different than the mono-
metalated cases, probably due to the presence of two strongly
donating, rigid, relatively inert, chelate ligands [31]. The complexes
showed emission at room temperature when excited at the
appropriate wavelength 420 or 435 nm. 3c and 5c have essentially
identical emission spectra, while 4c’s spectrum has its peak at
slightly higher wavelength (Fig. 6). All three emission spectra tail
off with a slight shoulder on the lower energy side. 4c has slightly
different spectra then its analogs probably due to the lack of
a methylene spacer between the phenyl ring and the metallacycle.
This missing spacer may allow for better conjugation and cause the
peak to shift to lower energy.
b
All six metal complexes have their emission peaks red-shifted
between 190 and 245 nm, characteristic of phosphorescence
emission expected from a triplet state typical for heavy metal
complexes with strong spin-orbit coupling [30,51]. All three bis-
cyclometalated complexes and 5b have larger red-shifts than the
two monometalated species 4b and 3b. 4c has the greatest shift at
245 nm, which can be attributed to the structure and the rigidity of
the ligands. 5b has a discernible shoulder on the higher energy side
of its peak while 3b and 4b have peaks that are very broad. All
bismetalated species have narrower bands with some slight
asymmetry. The lifetimes of the excited states for all six compounds
were determined and all were found to be in the 700e1300 ns
range, which is consistent with the above assignment. In addi-
tion, there is a very short-lived state (approx. 60 ns) for all of the
monometalated species but none of the bismetalated complexes.
This may be due to fluorescence from the excited singlet state or an
intraligand band. Quantum yields for all species are modest [32c],
with the monometalated species being the lowest (Table 2). Both
sets of the emission spectra and the absorbance spectra of all six
compounds had similar shape and relative ratio of band intensities
as a function of concentration.
Fig. 2. a) Molecular structure of compound 4b. b) Molecular structure of compound 4c.
DFT calculations were performed to help explain the electronic
spectra of the complexes. These calculations show that the pre-
dicted bands for the lowest energy transition can be explained by
charge transfer from HOMO to LUMO, which are mixed metal/
ligand-based and ligand-based respectively, whereby electron
density is moved from the platinum and coordinated thiophene to
the N]CeC]C ring attached to the metal (see S.I. for orbital
diagrams). This type of charge transfer is consistent among each of
the compounds 3c, 4c and 5c. All three compounds have remark-
ably similar orbital compositions for the HOMO ꢁ 1, HOMO, LUMO,
and LUMO þ 1 (Table 3). Similarly for compounds 3b and 4b, the
excitation from HOMO to LUMO moves electron density from
a mixed metaleligand HOMO to a ligand LUMO where electron
density is primarily transferred from the Pt-thiophene moiety to
the N]CeC]C ring. With 5b the energy of the HOMO and
Absorption spectra of 3c, 4c, and 5c are shown in Fig. 5. 3c and
c each have a pronounced peak at around 420 nm, and 4c has
a well-defined peak at 435 nm. These peaks have extinction coef-
ficients that are several times greater than the corresponding peaks
5
Table 1b
ꢀ
ꢀ
Selected bond lengths (A) and angles ( ) with estimated standard deviations for
compounds 4c.
Pt(1)eCl(1)
Pt(1)eN(1)
S(1)eC(1)
C(1)ePt(1)eC(12)
C(12)ePt(1)eN(1)
C(12)ePt(1)eN(2)
C(1)eS(1)eC(2)
1.969(3)
2.134(2)
1.712(3)
99.1(2)
177.6(1)
78.7(1)
Pt(1)eC(12)
Pt(1)eN(2)
S(2)eC(12)
C(1)ePt(1)eN(1)
C(1)ePt(1)eN(2)
N(1)ePt(1)eN(2)
C(12)eS(2)eC(13)
1.974(3)
2.141(2)
1.713(3)
78.6(1)
171.8(1)
103.7(1)
94.4(2)
93.9(2)

194
C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
Table 2
UV/vis and emission data.
ꢁ
1
ꢁ1
Lifetime nsa
61(1)
Complex
Absorption
l
max/nm (
3
/M cm
)
Emission
lmax/nm
Red shift
lmax/nm
Quantum yield %
3
4
5
3
a
a
a
b
252 (15,900), 296 (1980)
270 (16,000), 335 (3910)
250 (15,900), 296 (3090)
257 (17,800), 335 (2950), 381 (2070), 420 (718)
265 (19,000), 342 (5490), 391 (2780), 435 (1960)
258 (20,100), 336 (3100), 377 (2430), 420 (1040)
613
623
647
193
188
227
0.47
0.11
0.59
1
360(10)
178(2)
58(14)
60(5)
77(3)
4
b
b
7
5
8
3
4
c
c
260 (23,000), 295 (10,400), 360 (4390), 420 (8820)
264 (308,000), 290 (17,600), 320 (11,700), 365 (6540), 435 (7890),
650
680
230
245
1.2
0.25
1324(2)
705(1)
530 (1510)
5c
260 (28,600), 290 (14,600), 360 (5570), 420 (10,500)
650
230
1.2
839(2)
a
Error associated with lifetime value is given in parentheses.
HOMO-1 is reversed compared to 3b and 4b. This could be
explained due to the variation of the R group adjusting the energies
of the frontier orbitals. Given this reversal, it is interesting that the
emission spectrum of 5b is somewhat different than that of 3b and
NIR may possibly be of interest as red-emitting photosensitizers
with potential applications in biological systems as new
ruthenium/bipyridine/bicycliceguanidine complexes have been
reported with such an interest in mind. These ruthenium
complexes emit at longer wavelengths (around 740 nm), but have
shorter excited state lifetimes and lower quantum yields [52]. We
are currently testing our compounds in catalytic systems.
4
b, in that it has a larger red-shift and a well-defined shoulder at
higher energy. The composition of the orbitals and their energies
are shown in Table 3.
The predicted wavelengths of transitions based on these frontier
orbitals match reasonably well with the UV/vis data for the biscy-
clometalated complexes and aided our assignment of the absorp-
tion spectra as mixed metaleligand charge transfer to ligand [33].
In addition, the relative changes between HOMO/LUMO within
both the monometalated analogs and the bismetalated analogs
match the experimental values very well. For example, 3b and 5b
have very similar absorption maxima, while the maximum of 4b is
w20 nm higher in wavelength.
5. Experimental
5.1. General
1H and 13C NMR spectra were recorded using a Varian 400 MHz
1
13
( H, 400 MHz; C, 100 MHz) spectrometer, and referenced to
1
13
3 4
Si(CH ) ( H, C). d values are given in ppm and J values in Hz. IR
spectra were recorded on a Thermo-Nicolet FT-IR Spectrophotom-
eter with a diamond ATR. UVevis spectra were recorded using an
Agilent 8453 spectrophotometer.
4
. Concluding remarks
5.2. Photophysical measurements
Bismetalated platinum complexes were synthesized by several
different methods, including the reaction of a monometalated
precursor with a second sacrificial molecule. The complexes are
luminescent at ambient temperature, have lifetimes of around 1 ms,
and exhibit shifts in the emission spectra of w200 nm. This data is
characteristic of cyclometalated platinum complexes and consis-
tent with our electronic assignments. The compounds 5b, 5c, and
Steady-state emission spectra were recorded using a PTI QM-3
instrument with an R928 PMT detector, which is sensitive up to
50 nm. The solutions were de-gassed before spectra were taken
and the concentrations for the spectra in Figs. 4 and 6 were in the
8
ꢁ
5
ꢁ4
range 10 e10 M. Emission spectra were recorded using excita-
tion wavelengths of 420 nm for 3b, 5b, 3c, and 5c; and 435 nm for
3
c have intense emission peaks at around 650 nm, while 4c has its
3
[
c and 4c. Luminescence quantum yields were determined using
emission peak at around 690 nm and tails off up to 800 nm. Plat-
inum complexes with MLCT-type bands and an emission tail in the
Ru(bipy) ]Cl (in aqueous solution) as a standard following known
3
2
Fig. 4. Emission spectra for 3b, 4b, and 5b (excitation wavelength 420, 435, and
420 nm, respectively; concentration (6.78, 6.64, 7.36) ꢂ 10ꢁ M, respectively).
5
Fig. 3. UV/vis spectra for 3b, 4b, and 5b.

C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
195
Table 3
Orbital composition of HOMO and LUMO.
HOMO ꢁ 1
HOMO
LUMO
LUMO þ 1
Pt contribution to orbital (%D character)
3
4
5
3
4
5
b
b
b
c
c
c
89(72)
88(72)
34(34)
23(23)
22(22)
25(25)
36(36)
37(37)
78(41)
37(37)
33(33)
37(37)
7(4)
8(5)
1(1)
4(1)
7(7)
5(1)
1(w0)
13(3)
0(0)
8(8)
7(7)
8(8)
Energies in eV
3
4
5
3
4
5
b
b
b
c
c
c
ꢁ5.6053
ꢁ5.7111
ꢁ5.6500
ꢁ5.6195
ꢁ5.7969
ꢁ5.6083
ꢁ5.2097
ꢁ5.3424
ꢁ5.1993
ꢁ5.2453
ꢁ5.3887
ꢁ5.2467
ꢁ1.3023
ꢁ1.6776
ꢁ1.3113
ꢁ1.9399
ꢁ2.3206
ꢁ1.9225
ꢁ0.7818
ꢁ0.7372
ꢁ0.5426
ꢁ0.8694
ꢁ1.4526
ꢁ0.9301
Fig. 5. UV/vis spectra for 3c, 4c, and 5c.
normal operating conditions the resolution of the instrument was
w15,000 and the mass accuracy of the instrument was between 1
and 5 ppm; therefore, measured masses are given to three decimal
places. Data acquisition and analysis was performed using Agilent
MassHunter Workstation Acquisition Software and Agilent Mass-
Hunter Workstation Qualitative Analysis Software (Agilent Tech-
nologies, Santa Clara, CA), respectively. Exact masses and isotope
distributions were calculated using CS ChemBioDrawUltra.
procedures; uncertainties are estimated at 20% or better [32]. In
these experiments, concentrations of the metal species (in
ꢁ5
ꢁ4
ꢁ6
dichloromethane) ranged from 10 to 10
M for 3b; 10
to
ꢁ
5
ꢁ5
ꢁ3
1
0
M for 3c, 4c, 5c, and 5b; and 10 to 10 M for 4b. Temper-
ꢀ
atures were in the range of 25e26 C. The luminescence lifetimes of
the complexes were measured by time-correlated single-photon
counting following excitation at 405 nm with a pulsed-diode laser
in methylene chloride. All samples were de-gassed and had
concentrations adjusted so that the absorbance at 405 nm was
between 0.1 and 0.3 A.U. immediately prior to excitation and
measurement.
5.4. X-ray diffraction
X-ray diffraction data were collected on a Bruker APEX 2 CCD
ꢀ
platform diffractometer (Mo K
a
(l
¼ 0.71073 A)) at 125 K. Crystals
were mounted in a nylon loop with Paratone-N cryoprotectant oil.
The structure was solved using direct methods and standard
difference map techniques, and was refined by full-matrix least-
5.3. Mass spectrometry
3
The compounds were re-suspended in CHCl and were analyzed
in the positive mode using an Agilent 6520 electrospray ionization
quadrupole time-of-flight mass spectrometer. Using an Agilent 1100
3
HPLC system, 10 mL of sample was injected using CHCl as the
2
squares procedures on F with SHELXTL (Version 6.14) [53]. All non-
hydrogen atoms were refined anisotropically. Hydrogen atoms on
carbon were included in calculated positions and were refined
using a riding model. See Chart 1 for drawings and labels. Table 4
lists crystal data.
mobile phase and a flow rate of 0.4 mL/min. No column was used.
Samples were ionized by electrospray ionization in the positive
mode. Mass spectra were obtained scanning from 100 to 2000 at 1
spectra per second with the following instrument parameters:
Table 4
Summary of crystal data and intensity collection and structure refinement param-
eters for complexes 4c and 4b.
ꢀ
fragmentor voltage, 175 V; drying gas temperature, 325 C; drying
gas flow, 11 L/min; nebulizer pressure, 45 psig; capillary voltage,
Compound 4c
Compound 4b
17NPtS
458.50
4
000 V. Data were collected with the instrument set to 3200 m/z
Empirical
Formula C22
H
16
N
2
PtS
2
C
14
H
2
range under high resolution conditions at 4 GHz data acquisition
rate. Data were collected in profile mode. The instrument was cali-
brated using Agilent ESI-L low concentration tuning mix and under
Molecular weight
Crystal color, habit
Crystal size (mm)
567.58
Plate, red
0.20 ꢂ 0.20 ꢂ 0.02
0.20 ꢂ 0.20 ꢂ
.10 mm
0
Temperature (K)
Crystal system
Space group
125(2)
Monoclinic
C2/c
125(2)
Monoclinic
P2/n
Unit cell dimensions
ꢀ
a (A)
16.492(2)
10.2704(14)
22.112(3)
90
94.743(2)
90
3732.4(9), 8
2.020
7.752
8.0682(3)
17.7063(6)
10.7177(4)
90
107.05
90
1463.82(9), 4
2.080
9.852
2.30e30.53
99.8
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(o)
(o)
(o)
ꢀ
3
V (A ), Z
calc (mg m 3
Absorption coeff. (
ꢁ
D
)
, mm 1
ꢁ
)
m
ꢀ
F
range collected ( )
Completeness to
1.85e31.88
99.6
F max (%)
Reflns collected/unique (R(int))
16,061/5934 (0.0367)
23,547/4471
(
0.0229)
Data/restraints/parameters
R1, wR2 (I > 2sI)
5934/0/244
0.0239, 0.0537
0.0322, 0.0568
1.007
4471/0/166
0.0138, 0.0319
0.0156, 0.0325
1.026
R1, wR2 (all data)
Goodness of fit on F2
Largest diff peak/hole (e/A )
Fig. 6. Emission spectra for 3c, 4c, and 5c (excitation wavelength 420, 435, and
ꢀ
3
1.446, ꢁ1.064
1.216, ꢁ0.665
4
20 nm, respectively; concentration (1.17, 1.16, 11.0) ꢂ 10ꢁ5 M, respectively).

196
C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
5
.5. Computational work
for C15.5
2
H
21NOPtS
.82. Found: C ¼ 37.52; H ¼ 3.60; N ¼ 3.14.
Compound [Pt{(C S)CH]N(C )} ], 4c, was prepared by
three methods:
Method 1: 4c was obtained by refluxing
(CH -S(CH ] (77.3 mg, 0.134 mmol) with ligand 4a
2 3 2 2
(4b$0.5(CH ) CO$0.5H O): C, 37.49; H, 4.26; N,
The Gaussian03 suite of programs was used to do calculations
4
H
2
6
H
5
2
[54a]. DFT studies at the BL3LYP/LANL2DZ [54b] level were pre-
formed on all intermediates of a proposed pathway for the
formation of 3c (Scheme 2). Solvation was modeled with the self-
consistent reaction field (SCRF) calculations using the PCM-UA0
solvation model [55,56] and was carried out for the gas-phase
optimized structures. The solvation model otherwise used the
default parameters for the solvents chosen. Free energies are
taken at 298.15 K and 1 atm. All reported structures optimized to
ground states as confirmed by frequency analysis of each struc-
ture. Furthermore, in order to test whether the conformations of
the bimetallic species were reasonable multiple conformations
were energy optimized and each found the same lowest energy
structure.
a solution of
[Pt
2
3
)
4
(m
3 2 2
) )
(101 mg, 0.540 mmol) in a 1:4 ratio in anhydrous toluene (21 mL)
for 4 h. Removing the solvent resulted in a dark red powder which
was washed and triturated with cold diethyl ether. Yield: 66.8 mg
(43.7%). Method 2: 4c was obtained by stirring a solution of 4b
(11.8 mg, 0.0257 mmol) with ligand 4a (4.7 mg, 0.025 mmol) in
a 1:1 ratio in anhydrous toluene (21 mL) for 4 h. Removing the
solvent resulted in a dark red powder, which was washed and
triturated with cold diethyl ether. Yield: 2.9 mg (20.%). Method 3: 4c
was obtained by refluxing 4b (14.8 mg, 0.0322 mmol) in 10 mL of
anhydrous toluene for 1.5 h. Removing the solvent resulted in
a dark red powder. Yield: 2.2 mg (25%). [Pt{(C
4c. H NMR (400 MHz, CDCl ): d
3
4
H
2
S)CH]N(C
¼ {6.82e7.29, aromatics}; 8.16 [s,
):
6 5 2
H )} ],
1
5.6. Synthesis
3
a
a
13
J(PteH ) ¼ 67, 1H, H ]. C NMR (100 MHz, CDCl
3
d
¼ {121.77;
[
Pt
compound [PtCH
(S)-(C S)CH]NCH
(S)-(C S)CH]NCH
2
(CH
3
)4(
m
-S(CH
(S(CH
CH
CH
)], 6a, compound [PtCH
3
)
2
)
2
], 1, ligand [(C
){(C S)CH]NCH
(C )], 5a, compound [PtCH
(C )}], 5b, ligand [(R)-(C
(S(CH ){(R)-(C
4
H
3
S)CH]NCH
(C )}], 3b, ligand
(S(CH
2
(C
6
H
5
)], 3a,
126.13; 128.53; 158.30, aromatics}; {125.50 [s, J(PteC) ¼ 49];
3
3
)
2
4
H
2
2
6 5
H
126.93 [s, J(PteC) ¼ 58]; 148.49 [s, J(PteC) ¼ 33]; 149.37, thio-
2
a
[
{
4
H
3
2
3
6
H
H
5
3
3
)
2
)
phene}; 169.57 [ J(PteC) ¼ 62, Me ]. ESI-MS (m/z): Found: m/z
4
H
2
2
3
6
5
4
H
H
3
S)CH]
S)CH]
[567.0441], Calcd for [Pt{(C
Elemental Analysis Calc. for C22
3.10; N, 4.78. Found: C, 45.39; H, 2.98; N, 4.57.
Compound [Pt{(S)-(C S)CH]NCHCH (C
by three methods.
Method 1: 5c was obtained by reacting [Pt
4
H
2
S)CH]N(C
6
H
5
)}
2
]: m/z [567.0455].
O): C, 45.12; H,
NCH
NCH
2
CH
CH
3
3
(C10
(C10
H
H
7
3
3
)
2
4
2
H
18
N
2
OPtS
2
(4c$H
2
2
7
)}], 6b, were prepared as reported [42,44,45].
S)CH]NCH (C )} ], 3c, was prepared by
the three methods. Method 1: 3c was obtained by refluxing ligand 3a
70.1 mg, 0.348 mmol) with [Pt (CH -S(CH ] (50.0 mg,
.0871 mmol) in a 4:1 ratio in anhydrous toluene (20 mL) for 30 min.
Compound [Pt{(C
4
H
2
2
6
H
5
2
4
H
2
3
6
H
5
)}
2
], 5c, was prepared
(
0
2
3
)
4
(
m
3
)
2
)
2
2
(CH
3
)
4
3 2 2
(m-S(CH ) ) ]
(50.0 mg, 0.0871 mmol) with ligand 5a (75.4 mg, 0.350 mmol) in a 1:4
ratio in anhydrous toluene (18 mL). The solution was allowed to reflux
for 11 h before being washed and triturated in cold diethyl either,
resulting in a brown powder. Yield: 40.8 mg (37.6%). Method 2: 5c was
obtained by reacting compound 5b (20.5 mg, 0.0421 mmol) with
ligand 5a (8.9 mg, 0.041 mmol) in toluene (10 mL) in a 1:1 ratio. The
solution was allowed to reflux for 2 h before being washed and tritu-
rated in cold diethyl either, resulting in a brown powder. Yield: 3.6 mg
(14%). Method 3: 5c was obtained by refluxing compound 5b (26.1 mg,
0.0536 mmol) in anhydrous toluene (20 mL). The solution was allowed
The resulting brown powder was washed and triturated in cold diethyl
ether. Yield: 57.7 mg (55.6%). Method 2: 3c was obtained by refluxing
ligand 3a (8.9 mg, 0.044 mmol) with compound 3b (20.0 mg,
0.0423 mmol) in anhydrous toluene (20 mL) in a 1:1 ratio for 2 h. The
resulting brown powder was washed and triturated in cold diethyl
ether. Yield: 11.8 mg (46.8%). Method 3: 3c was obtained by refluxing
compound 3b (15.3 mg, 0.0324 mmol) in anhydrous toluene (35 mL)
1
for 1 h. Yield: 7.1 mg (74%). [Pt{(C
4
H
2
S)CH]NCH
2
(C
6
H
5
)}
2
], 3c. H NMR
3
b
b
(
400 MHz, CDCl
3
):
d
¼ 4.70 [s, J(PteH ) ¼ 12, 2H, H ]; {7.13e7.38,
3 a a 13
aromatics}; 7.98 [s, J(PteH ) ¼ 70, 1H, H ]. C NMR (100 MHz,
4 2 3 6 5 2
to reflux for 1 h. Yield: 2.9 mg (17%). [Pt{(C H S)CH]NCHCH (C H ],
)}
b
f
1
4
e
e
3
CDCl ):
d
¼ 62.10 [C ]; {126.72; 127.41; 128.95; 156.96 [s, C ],
3
5c. H NMR (400 MHz, CDCl d
):
¼ 1.64[d, J(PteH )¼ 7, 3H, H ]; 5.19 [d,
3
b
b
3
a
aromatics}; {126.56 [s, J(PteC) ¼ 57]; 124.86 [s, J(PteC) ¼ 48]; 138.23
J(PteH ) ¼ 7, 1H, H ]; {6.99e7.52, aromatics}; 7.96 [s, J(PteH ) ¼ 70,
h
g
3
a
a
a
13
e
b
[
s, C ]; 147.23 [s, C ], thiophene}; 171.13 [s, J(PteC ) ¼ 66, C ]. ESI-MS
m/z): Found: m/z 595.0771, Calculated for [Pt{(C S)CH]
NCH (C )} ]: m/z 595.0767. Elemental Analysis Calc. for
(3c$0.5(CH CO$H O): C, 47.65; H, 3.92; N, 4.36.
Found: C ¼ 47.80; H ¼ 3.49; N ¼ 4.38.
Ligand [(C S)CH]N(C )], 4a, was obtained by stirring a 1:1
1H, H ]. C NMR (100 MHz, CDCl
3
):
d
¼ 21.32 [C ]; 62.76 [s, C ]; {124.95
(
4
H
2
[s, J(PteC) ¼ 48]; 126.46; 141.06; 148.12, thiophene}; {127.64; 127.85;
a
2
6
H
5
2
128.95; 155.59, aromatics}; 167.37 [C ]. ESI-MS (m/z): Found: m/z
C
25.5
H
25
N
2
O
1.5PtS
2
3
)
2
2
623.1092, Calculated for [Pt{(C
623.1080. Elemental Analysis Calc. for C26
47.99; H, 4.18; N, 4.30. Found: C, 47.82; H, 3.70; N, 3.95.
Ligand [(C S)CH]NCH )], 7a, was obtained by reacting
4 2 3 6 5 2
H S)CH]NCHCH (C H )} ]: m/z
H
27
N
2
O
1.5PtS
2
2
(5c$1.5H O): C,
4
H
3
6 5
H
ratio of 3-thiophene carboxaldehyde (602 mg, 5.37 mmol) and
aniline (500. mg, 5.37 mmol) in methylene chloride (17 mL) for
4
H
3
2 7
(C10H
1-naphthalene methylamine (228 mg, 1.45 mmol) with 3-thio-
phene carboxaldehyde (169 mg, 1.51 mmol) in ethanol (20 mL) and
9
0 min. This was dried over MgSO
oil. Yield: 813 mg (80.9%). [(C
400 MHz, CDCl ):
4
and filtered, yielding a brown
1
4
H
3
S)CH]N(C
6
H
5
)], 4a. H NMR
refluxing for
NCH )], 7a. H NMR (400 MHz, CDCl
8.40 [s, 1H, H ]. ESI-MS (m/z): Found: m/z [252.0828], Calculated for
[(C S)CH]NCH )]: m/z [252.0841].
Compound [PtCH (S(CH ){(C S)CH]NCH
was obtained by reacting [Pt (CH -S(CH
4 3
3 h. Yield: 48.7 mg (13.3%). [(C H S)CH]
a
1
b
(
3
d
¼ {7.26e7.80, aromatics}; 8.48 [s, 1H, H ]. ESI-
2
(C10
H
7
3
):
d
¼ 5.26 [s, 2H, H ];
a
MS (m/z): Found: m/z 188.0530, Calcd for [(C
m/z 188.0528.
4
H
3
6 5
S)CH]N(C H )],
4
H
3
2 7
(C10H
Compound [PtCH
3
(S(CH
3
)
2
){(C
4
H
2
S)CH]N(C
6
H
5
)}], 4b, was
3
3
)
2
4
H
2
2
(C10
7
H )}], 7b,
obtained by combining [Pt
2
Me
4
(
m
-SMe
2
)
2
] (76.4 mg, 0.133 mmol)
2
3
)
4
(
m
) ) ] (75.0 mg,
3 2 2
dissolved in acetone (25 mL) with ligand 4a (49.9 mg, 0.266 mmol)
in a 1:2 ratio. The solution was stirred for 90 min at room
temperature. The resulting orange solid was washed in cold diethyl
ether. Yield: 47.0 mg (38.5%). This contained two isomers in an
approximate 5:1 ratio. The isomer in least abundance was washed
0.131 mmol) with ligand 7a (65.0 mg, 0.259 mmol) in acetone
(20 mL) and stirring the solution at room temperature for 16 h. It
was then washed and triturated in cold diethyl ether, resulting in an
orange powder. Yield: 58.3 mg (43.1%). [PtCH
3
(S(CH
3 2 4 2
) ){(C H S)
1
CH]NCH
2
(C10
H
7
)}], 7b. H NMR (400 MHz, CDCl
3
):
d
¼ 1.18 [s, 3H,
c
3
d
3
b
away with cold ether to afford a pure product. [PtCH
3
(S(CH
¼ 1.23 [s,
J(PteH ) ¼ 81, 3H, H ]; 2.13 [s, J(PteH ) ¼ 30, 6H, H ]; {7.17e7.42,
3
)
2
)
H ]; 2.06 [s, J(PteH) ¼ 16, 6H, H ]; 5.47 [s, J(PteH) ¼ 10, 2H, H ];
1
3 a
{
(C
4
H
2
S)CH]N(C
6
H
5
)}], 4b. H NMR (400 MHz, CDCl
3
):
d
8.34 [s, J(PteH) ¼ 52, 1H, H ].
Compound [Pt{(C S)CH]NCH
by refluxing compound 7b (21.2 mg, 0.0406 mmol) in anhydrous
2
c
c
3
d
d
4
H
2
2 7 2
(C10H )} ], 7c, was obtained
3
a
a
aromatics}; 8.36 [s, J(PteH ) ¼ 48,1H, H ]. Elemental Analysis Calc.

C.M. Anderson et al. / Journal of Organometallic Chemistry 723 (2013) 188e197
197
toluene (20 mL) for 3 h. It was then washed and triturated in cold
diethyl ether, resulting in an impure black powder. However NMR
[26] Q. Zhao, F. Li, S. Liu, M. Yu, Z. Liu, T. Yi, C. Huang, Inorganic Chemistry 47
2008) 9256e9264.
(
[
27] D.A.K. Vezzu, J.C. Deaton, J.S. Jones, L. Bartolotti, C.F. Harris, A.P. Marchetti,
M. Kondakova, R.D. Pike, S. Huo, Inorganic Chemistry 49 (2010) 5107e
5119.
and mass spec were obtained with impurities present. [Pt{(C
4
H
2
S)
¼ 5.02 [s, 2H,
H ]; 7.94 [s, 1H, H ]. ESI-MS (m/z): Found: m/z 695.1082, Calculated
for [Pt{(C S)CH]NCH )} ]: m/z 695.1080.
1
2 7 2 3
CH]NCH (C10H )} ], 7c. H NMR (400 MHz, CDCl ): d
b
a
[28] Z. He, W.-Y. Wong, X. Yu, H.-S. Kwok, Z. Lin, Inorganic Chemistry 45 (2006)
0922e10937;
1
4
H
2
2
(C10H
7
2
b) G. Zhou, Q. Wang, C. Ho, W. Wong, D. Ma, L. Wang, Chemical Communi-
cations (2009) 3574e3576.
[
[
[
[
29] J. Brooks, Y. Babayan, S. Lamansky, M.E. Thompson, Inorganic Chemistry 41
Acknowledgments
(2002) 3055e3066.
30] K. Hanson, A. Tamayo, V.V. Diev, M.T. Whited, P.I. Djurovich, M.E. Thompson,
Inorganic Chemistry 49 (2010) 6077e6084.
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This material is based uponwork supported by the National Science
Foundation under CHE e 1058936 (Craig M. Anderson, P.I.). Theauthors
thank Bard College (including Bard Summer Research Institute) for
financial help. Mass spectrometry was performed using instrumenta-
tion supported by funding from a National Science Foundation Major
Research Instrumentation Grant (#1039659, Teresa A. Garrett, P.I.). We
thank Daniel Chartrand for help with lifetime measurements and the
NSF Center for Enabling New Technologies through Catalysis (CENTC)
for useful discussions and for computational support.
(2010) 476e487.
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Appendix A. Supplementary information
Supplementary data related to this article can be found at
http://dx.doi.org/10.1016/j.jorganchem.2012.10.027.
[
[
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