A new approach to light-gated Pt catalysts for the hydrosilylation

Article abstract of DOI:10.1016/j.jorganchem.2013.04.045

A new concept for a light-gated transition metal catalyst is presented based on a photo-active moiety in the outer ligand sphere of the complex which on irradiation reacts irreversibly with some part of the inner ligand sphere releasing a free coordination site. The principle is exemplified on a platinum complex for the hydrosilylation. It is proven that the catalytic properties of the complex and the properties of the photo-gate can be fine-tuned on the chemical problem independently of each other.

Full text of DOI:10.1016/j.jorganchem.2013.04.045

Journal of Organometallic Chemistry xxx (2013) 1e8
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
A new approach to light-gated Pt catalysts for the hydrosilylation
,
Magnus R. Buchner a, Bettina Bechlars b, Klaus Ruhland c
*
a Institut für Siliciumchemie, Lehrstuhl für Anorganische Chemie, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching,
Germany
b Lehrstuhl für Anorganische Chemie, Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
c Lehrstuhl für Chemische Physik und Materialwissenschaften, Institut für Physik, Universität Augsburg, Universitätsstr. 1, Augsburg D-86159, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
A new concept for a light-gated transition metal catalyst is presented based on a photo-active moiety in
the outer ligand sphere of the complex which on irradiation reacts irreversibly with some part of the
inner ligand sphere releasing a free coordination site. The principle is exemplified on a platinum complex
for the hydrosilylation. It is proven that the catalytic properties of the complex and the properties of the
photo-gate can be fine-tuned on the chemical problem independently of each other.
Ó 2013 Elsevier B.V. All rights reserved.
Received 14 February 2013
Received in revised form
21 April 2013
Accepted 28 April 2013
Keywords:
Photo-gated catalysis
Hydrosilylation
Pt complexes
1. Motivation
context with Ruthenium complexes on this purpose [5]. Photo-
caged Ruthenium complexes have also been applied to other cat-
Cross-linked polysiloxanes are the material of choice for the
encapsulation of LED’s and LED lenses [1]. However the normally
heat-induced catalysts for the cross-linking hydrosilylation (in
general inhibited derivatives of Karstedt’s catalyst) show too slow
reaction rates due to difficulties to distribute the heat fast enough
within the material and also show too low shelf times [2]. An
improvement would be a light-activated catalyst with high activ-
ities at ambient temperatures, once being activated.
alytic reactions [6]. Another strategy was to induce reductive
elimination, in particular of H2, by irradiation [7]. The activated
fragments are very reactive and will in general show CeH activa-
tion in a stoichiometric reaction. Weak metalemetal bonds have
also been used as target for photo-activation [8]. Concerning
hydrosilylation, photo-caged examples can be found in the patent
literature [9]. But these catalysts are less reactive than Karstedt’s
catalyst, they show to a decisive degree side reactions because of
radical intermediates on UV-irradiation and they are difficult to
modify, since the photo-process, causing the ligand dissociation,
involves directly the metal/ligand bond. The scientific literature
also provides some examples using Pt(acac) complexes and gold
nano-particles [10]. Scheme 1 summarizes the most important
examples.
2. Introduction
Although light is a very attractive stimulus for reactivity, the
development of artificial light-gated catalysts is still on a very basic
level [3]. One can in particular distinguish between photo-catalytic,
photo-caged and photo-switchable systems. Concerning transition
metal catalysts the photo-caged systems are by far most explored,
though still with quite few examples. In most cases a ligand is
directly eliminated by action of light. Carbon monoxide is the most
prominent moiety, extruded by irradiation of UV light to activate a
transition metal complex [4]. Olefin metathesis is the main target
reaction for photo-caged catalyst systems until now. Beside CO, li-
gands such as nitriles, arenes and acac are extruded exclusively in
We herein present a new approach towards light-gated Pt
complexes which can easily be transferred at least to other group 10
metals and also allows a simple fine-tuning of the gate to different
applications and conditions.
3. The novel concept
Our idea is based on separating the photo-gate from the inner
ligand sphere in contrast to the known examples. As a consequence,
the inner ligand sphere can be fine-tuned independently of the
photo-gate for the chemical problem. This is brought about by
introducing a photo-active outer ligand sphere which on irradiation
* Corresponding author. Tel.: þ49 8215983361.
E-mail address: klaus.ruhland@physik.uni-augsburg.de (K. Ruhland).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.04.045
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2
M.R. Buchner et al. / Journal of Organometallic Chemistry xxx (2013) 1e8
CH3
CH3
CH3
H3C
H3C
O
O
O
Me2
Pt
Si
CH3
CH3
H3C
Pt
Pt
O
O
O
CH3
CH3
Pt
H3C
H3C
Pt
Si
CH3
Me2
O
H3C
CH3
Scheme 1.
reacts with the inner ligand sphere in a defined manner, activating
the pre-catalyst for the catalytic cycle (Scheme 2).
range of hours in solution even in the dark. Irradiated at 300 nm or
419 nm in toluene, the decomposition is observed within minutes,
pointing to the fact that the gateworks adequately. If the irradiation is
performed in the presence of one equivalent of PPh3, Pt(PPh3)3 is
formed, detected by 31P NMR spectroscopy, and the olefinic signals of
the gate-ligand disappear in the 1H NMR spectrum.
Without irradiation the light gate is not released from [1]Pt by
action of 1 equivalent of PPh3 at least for hours as was already
shown during the synthesis of it (Scheme 6).
Thus, also the photo-active moiety in the pre-catalyst can
independently be adjusted to the reaction conditions of choice and
the complete ligand can be applied to different transition metals.
The system is decisively more flexible and more general than all
known solutions.
4. The prove of principle
Thus, it was proven, that [1]Pt can be activated by irradiation. To
further prove that this is really due to our gate in the outer ligand
sphere and not because of inner-ligand-sphere effects, we exam-
ined the analogous complex with a keto- rather than a diazo-
function [10]Pt. [10]Pt is received as a white powder, thermally
stable at ambient temperatures for months under argon. We were
able to obtain an X-ray analysis of [10NO2]Pt with a nitro group in
para-position of the cinnamate phenyl group. Yellow crystals were
generated by slow diffusion of pentane into a toluene solution. A
depiction of it in the solid state is shown in Fig. 1.
To prove our new concept, we applied ligand 1 in Scheme 3 to Pt.
The synthesis of this ligand was performed in three steps.
Ligand 1 shows an absorption band in the UV spectrum at
282 nm. It is stable in air at ambient temperature for hours, but
should be stored at ꢀ35 ꢁC for longer times (months).
If this gate-ligand is irradiated at 300 nm at ambient tempera-
tures, a quantitative transformation into two products, which could
be isolated and characterized, within minutes is observed
(Scheme 4).
The kinetics and a mechanistic proposal were determined by us
[11].
This experiment proves that a fast defined and quantitative re-
action of the photo-active moiety with the coordinating functional
group at a defined wave length is possible.
The P1ePteP2 angle is 108.4ꢁ. The distance C37eC38 between
ꢀ
the olefinic carbon atoms is 1.449 A. The PteP distances are PteP1
ꢀ
2.296 A and PteP2 2.284 Å.
[10]Pt and [10NO2]Pt were both stable on irradiation with or
without the presence of additional PPh3, and proved that our outer-
sphere-gate-concept is valid (Scheme 6).
Ligand 1 can be coordinated to Pt0 in a ligand-exchange-reaction
with Pt(PPh3)3 in 84% yield to result in [1]Pt (Scheme 5).
[1]Pt was obtained as light red solid with sharp signals in its NMR
spectra, proving no fluxionality in the bonding mode of 1 at ambient
temperatures (in contrast to the analogous Pd complexes [12]). Two
sharp doublets with 195Pt satellites are observed for the two distin-
guishable P-atoms of the PPh3 ligands in 31P NMR spectroscopy. [1]Pt
decomposes in solution immediatelyand asa solid within minutes on
air. Under argon at ꢀ30 ꢁC it is long-term stable as a solid. At ambient
temperature this complex decomposes slowly thermally over the
The reaction of [1]Pt with H2SiPh2 as the next milestone showed
that the equilibrium is decisively on the side of oxidative addition
already without irradiation (Scheme 7).
Accordingly, 1 was not bound strongly enough to the Pt centre
for a light-gated catalyst. We, thus, decided to modify the cinna-
mate moiety, adding a nitro group in para-position of the phenyl
group comparable to [10NO2]Pt and enforcing the metal-to-ligand-
back-bonding in [1NO2]Pt. This compound was obtained as an or-
ange solid in 90% from 1NO2 and (PPh3)2Pt(ethene). In the UV
inactive pre-catalyst
HSiR'3
L
L
L
L
S
S*
S
S
Pt0
Pt0
Pt0
Pt
L
L
L
H
hν
L
L
HSiR'3
L
L
L
SiR'3
R
R
R
L
S
further
catalytic
cycle
Pt0
L
L
HSiR'3
R
Scheme 2.
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M.R. Buchner et al. / Journal of Organometallic Chemistry xxx (2013) 1e8
3
O
O
Cl
O
O
pyridine, 100°C
OH
O
H
N
toluene
TsOH cat.
reflux
H2N
S
O2
O
O
O2S
NH
O
N2
O
N
(1)
1. NaH, thf, 0°C
2. toluene, reflux
Scheme 3.
O
O
O
O
N2
O
hν (300 nm)
toluene
-N2
(1)
O
Scheme 4.
spectrum, [1NO2]Pt showed a band at 276 nm for the diazo moiety
and, thus, comparable to [1]Pt. Indeed, on doing so, the equilibrium
in Scheme 7 was completely shifted towards the olefin complex in
the presence of one equivalent of H2SiPh2, and the olefin complex
was stable without irradiation. When irradiation was turned on, the
colour of the solution changed immediately from deep orange,
typical for complex [1NO2]Pt, to yellow ((PPh3)2PtH(SiHPh2) is col-
ourless, the cyclization products of 1NO2 is yellow). In the 31P NMR
spectrum the two doublets of the inequivalent phosphorus atoms
vanished and a broad signal at 36 ppm appeared for the two P-
atoms in (PPh3)2PtH(SiHPh2) which are in fast exchange on the
spectral time scale of 31P NMR spectroscopy [13]. The formation of
the oxidative addition product was further indicated by a broad
The reaction was monitored by 19F NMR spectroscopy. Fig. 2
shows the time/conversion diagram for [1NO2]Pt in the absence of
irradiation in comparison to Pt(PPh3)3 as catalyst.
As can be seen at the very beginning of the conversion the reaction
with [1NO2]Pt is slower compared to Pt(PPh3)3 as expected. But [1NO2
]
Pt shows a decisive thermal reactivity even in the dark, and after 5 h
thebehaviourinverts. The reactionproceedseven faster with [1NO2]Pt
(in the dark). This is because of the thermal decomposition of [1NO2]Pt
at ambient temperatures. Decomposed [1NO2]Pt leads to Pt(PPh3)2
which in contrast to Pt(PPh3)3 does not liberate free PPh3 as an
inhibiting ligand during the catalytic cycle. This is the reason why at
ambient temperatures without irradiation the reaction becomes
faster with [1NO2]Pt than with Pt(PPh3)3. Thus, in principle our
concept was confirmed, but as a new problem the lability of the light-
gate was diagnosed. To solve this problem we changed from the
benzophenyl moiety to a fluorenyl moiety in [2NO2]Pt (Scheme 9).
2NO2 shows a band at 285 nm in the UV spectrum, quite com-
parable to 1. [2NO2]Pt was received as an orange solid in 91% yield in
the ligand exchange reaction between 2NO2 and (PPh3)2Pt(ethen).
This compound is indeed stable as a solid as well as in solution at
ambient temperature and can even be handled in air for a short
time as a solid.
2
hydride signal in the 1H NMR spectrum at 1.2 ppm with a JHP
coupling constant of 130 Hz (the smaller cis-coupling is not
resolved because of the above-mentioned dynamic behaviour in
this compound) (Scheme 7). After 180 min of irradiation no [1NO2
]
Pt was detectable any more by 31P NMR spectroscopy. This exper-
iment further supports that our concept of a light-gated catalyst is
valid. Additionally this is a nice example for the fact that in our
system the inner ligand sphere can be fine-tuned independently of
the light-gate to the problem under investigation.
[1NO2]Pt was next tested in the catalytic hydrosilylation of para-
fluoro acetophenone with H2SiPh2 at ambient temperature in
methylene chloride as depicted in Scheme 8.
Tested as a catalyst in the hydrosilylation of Scheme 8, the time/
conversion diagram shows that on irradiation the activity of [2NO2]Pt
is significantly increased, but still a reactivity was present without
Ph3P
PPh3
O
O
Pt
O
N2
- PPh3
O
N2
+ Pt(PPh3)3
(1)
benzene
[1]Pt
Scheme 5.
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4
M.R. Buchner et al. / Journal of Organometallic Chemistry xxx (2013) 1e8
intramolecular cyclopropanation reaction with a double bond of
the inner sphere of that complex. It was shown that the light-gate
works in the proposed manner. Also, it could be proven that the
stability of the inner sphere and the thermal robustness of the light
gate can be independently optimized without leaving the basic
concept, which up to now was a draw-back of all comparable
existing light-gated systems.
dark
dark
with or without PPh
with or without PPh
Ph3P
PPh3
O
Ph3P
PPh3
O
Pt
Pt
O
N2
O
O
At the moment we are further exploring our concept to provide
a catalyst which is more stable without irradiation and more
reactive after irradiation than any other known catalyst, by sys-
tematically applying well-known concepts of chemistry, such as
chelating effects, on our new approach and, thus, further proving
the generality of this principle.
[1]Pt
[1']Pt
hν
hν
PPh3
PPh3
hν
hν
decomposition
Pt(PPh3)3
Scheme 6.
6. Experimental section
All manipulations and experiments were performed under
argon using standard Schlenck techniques and in a glovebox
filled with argon unless otherwise stated. Pentane was dried and
degassed using a two-column drying system (MBraun) [14],
benzene and toluene were distilled from sodium. All solvents
were stored under an argon atmosphere. CD2Cl2 was dried over
CaH2, distilled and degased by three freezeepumpethaw cycles,
benzene-d6 and toluene-d8 were dried and degased by stirring
over sodium potassium alloy and purified by condensation.
Diphenylsilane, acetophenone and p-fluoroacetophenone were
bought from Aldrich and degased by three freezeepumpethaw
cycles prior to use. 4-Toluenesulfonic acid monohydrate and so-
dium hydride were purchased from Merck, 4-nitro-cinnamic acid
from Aldrich and used without further purification. 1-Hydroxy-9-
fluorenone [15], the acid chlorides [14,16], cinnamate esters [12],
diphenyldiazo esters [11], Pt(PPh3)3 [17] and Pt(PPh3)2C2H4 [18],
irradiation, in spite of the fact that [2NO2]Pt is thermally stable at
ambient temperature in solution (Fig. 3).
The reason is that with H2SiPh2 in excess under catalytic con-
ditions the dissociation equilibrium in Scheme 7 is shifted partly
towards the oxidative addition.
Still we emphasize that our new concept for an independently
tuneable light-gated transition metal complex was unequivocally
proven in this work.
5. Conclusion
It could be shown that a light-gated cleavage of a coordinated
olefin ligand is possible under mild conditions via the photo-
induced generation of a carbene from a diazo moiety in the outer
ligand sphere of
a
platinum complex and subsequent
were synthesized according to literature procedures. 1H NMR, 13
C
NMR and 31P NMR measurements were performed on a Bruker
Avance III 400 and 195Pt NMR measurement on a Bruker AMX
400. 1H NMR (400 MHz) and 13C NMR (100 MHz) chemical shifts
are given relative to the solvent residue signal for CD2Cl2 (5.32
and 53.8)/C6D6 (7.15 and 128.1)/C7D8 (2.09 and 20.4) [19], 31P
NMR (162 MHz) used 85% H3PO4 and 195Pt NMR (85 MHz) used
Na2PtCl6 in D2O as an external standard. FAB-MS analysis was
carried out on a Finnigan MAT-90 in a para-nitrobenzylalcohol
matrix under bombardment with ionised xenon. ESI-MS were
conducted on a Finnigan LCQ in acetonitrile. Micro analytical
analysis was performed in the micro analytical lab of the Tech-
nische Universität München. ATR FT-IR spectroscopy was done
with a Thermo Scientific Nicolet 380 Smart Orbit. UV/vis spectra
were recorded on a Jasco V-550 spectrophotometer using quartz
cuvettes.
X-ray single crystal parameters were obtained the following:
The single crystals were stored under perfluorinated oil, transferred
into a Lindemann capillary, fixed and sealed. Preliminary exami-
nation and data collection were carried out on an area detecting
system (APEX II,
k-CCD) at the window of a rotating anode (Bruker
AXS, FR591) and graphite monochromated MoKa radiation
ꢀ
(l
¼ 0.71073 A). Raw data were corrected for Lorentz, polarization,
and, arising from scaling procedure, for latent decay and absorption
effects. The structures were solved by a combination of direct
methods and difference Fourier syntheses. All non-hydrogen atoms
were refined with anisotropic displacement parameters, whereas
all hydrogen atoms were refined with isotropic displacement pa-
rameters. Full-matrix least-square refinements were carried out by
minimizing P(F20 ꢀ Fc2)2 with SHELXL-97 weighting scheme [20].
The final residual electron density maps showed no remarkable
features. Neutral atom scattering factors for all atoms and
Fig. 1. Depiction of a molecule in the solid state of [10NO2]Pt.
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M.R. Buchner et al. / Journal of Organometallic Chemistry xxx (2013) 1e8
5
Ph3P
PPh3
O
+ H2SiPh2
N2
R = NO2
Pt
R = H
hν
Ph3P
PPh3
H
Ph3P
PPh3
H
- ligand 1
Pt
O
Pt
NO2
+ ligand 1
+ ligand 1
Ph2HSi
Ph2HSi
R
Scheme 7.
anomalous dispersion corrections for non-hydrogen atoms were
taken from International Tables for Crystallography [21].
Route A: 100 mg (0.10 mmol) Pt(PPh3)3 and 0.10 mmol of the
appropriate ligand were dissolved in toluene and stirred for 1 h.
After removal of the solvent in vacuo the residue was stirred with
pentane over night. The solvent was decanted off and the residue
washed twice with pentane to give the product.
Route B: 75.0 mg (0.10 mmol) Pt(PPh3)2C2H4 were dissolved in
5 ml of benzene, added to 0.10 mmol of the appropriate ligand and
stirred for 1 h. After lyophilization the residue was stirred in
pentane over night. The solvent was decanted off and the obtained
powder dried in vacuo to yield the desired complex in micro
analytical grade.
6.1. Bis(triphenylphosphine)-(h
2-2-(diazo(phenyl)methyl)phenyl
cinnamate)platinum(0) ([1]Pt)
Light red solid, yield: 84%, route A. 1H NMR (C6D6):
d
¼ 3.91 (dpt,
3JHH ¼ 8.6 Hz, 3JHP ¼ 5.6 Hz, 3JHP ¼ 8.6 Hz, 1H, CHCHCO), 3.91 (ddpt,
3
3
2
3JHH ¼ 8.6 Hz, JHP ¼ 5.6 Hz, JHP ¼ 8.6 Hz, JHPt ¼ 50.0 Hz, 1H,
CHCHCO), 4.23 (dpt, 3JHH ¼ 8.6 Hz, 3JHP ¼ 5.4 Hz, 3JHP ¼ 8.6 Hz, 1H,
3
3
3
C
ArCHCH), 4.23 (ddpt, JHH ¼ 8.6 Hz, JHP ¼ 5.4 Hz, JHP ¼ 8.6 Hz,
2JHPt ¼ 56.6 Hz, 1H, CArCHCH), 6.22 (d, 3JHH ¼ 7.0 Hz, 2H, HAr), 6.45
3
(d, JHH ¼ 6.2 Hz, 2H, HAr), 6.67e7.24 (m, 32H, HAr), 7.33e7.55 (m,
6H, HAr). 31P NMR (C6D6):
d
¼ 27.6 (d, JPP ¼ 40.6 Hz), 27.6 (dd,
2
2JPP ¼ 40.6 Hz, 1JPPt ¼ 4185.3 Hz), 28.6 (d, 2JPP ¼ 40.6 Hz), 28.6 (dd,
2JPP ¼ 40.6 Hz, 1JPPt ¼ 3634.4 Hz).
SiHPh
O
O
"Pt"
(h ν)
+
H2SiPh2
H
F
F
NO2
O
Ph3P PPh
O 3
Pt
O
O
O2N
+
+
N2
O
N2
O2N
O
h ν
Ph3P Pt PPh3
O
SiHPh2
H2SiPh2
H
F
Ph3P SiHPh2
Pt
Ph3P SiHPh2
Pt
Ph3P
O
Ph3P
H
H
F
O
F
Scheme 8.
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6
M.R. Buchner et al. / Journal of Organometallic Chemistry xxx (2013) 1e8
Fig. 3. Time/conversion diagram for the hydrosilylation in Scheme 8 with [2NO2]Pt in
the dark and on irradiation at 300 nm.
(ddpt, 3JHH ¼ 8.7 Hz, 3JHP ¼ 4.4 Hz, 3JHP ¼ 8.7 Hz, 2JHPt ¼ 59.8 Hz, 1H,
CHCHCO), 3.81 (dpt, 3JHH ¼ 8.7 Hz, 3JHP ¼ 5.6 Hz, 3JHP ¼ 8.7 Hz, 1H,
3
3
3
C
ArCHCH), 3.81 (ddpt, JHH ¼ 8.7 Hz, JHP ¼ 5.6 Hz, JHP ¼ 8.7 Hz,
2JHPt ¼ 51.3 Hz, 1H, CArCHCH), 6.28 (d, 3JHH ¼ 5.5 Hz, 2H, HAr), 6.73e
7.10 (m, 28H, HAr), 7.42e7.58 (m,12H, HAr), 7.91 (d, 3JHH ¼ 7.6 Hz, 2H,
2
2
HAr). 13C NMR (C6D6):
d
¼ 49.2 (dd, JCP ¼ 5.4 Hz, JCP ¼ 27.7 Hz,
CHCHCO), 49.2 (ddd, 2JCP ¼ 5.4 Hz, 2JCP ¼ 27.7 Hz, 1JCPt ¼ 190.7 Hz,
2
2
CHCHCO), 61.9 (dd, JCP ¼ 3.9 Hz, JCP ¼ 33.1 Hz, CArCHCH), 61.9
(ddd, 2JCP ¼ 3.9 Hz, 2JCP ¼ 33.1 Hz, 1JCPt ¼ 195.7 Hz, CArCHCH), 124.6,
124.7, 125.1, 126.7, 126.7, 128.3,128.7, 129.1, 129.2,130.0,130.1, 130.3,
130.6, 131.6, 133.2, 133.5, 134.6, 134.8, 134.8, 134.9, 135.0, 135.7 (d,
Fig. 2. Time/conversion diagram for the reaction in Scheme 8 with [1NO2]Pt (red) and
Pt(PPh3)3 (black) as catalyst without irradiation (exact conditions given in the exper-
imental section). (For interpretation of the references to colour in this figure legend,
the reader is referred to the web version of this article.)
1JCP ¼ 3.0 Hz, CArP), 135.7 (dd, 1JCP ¼ 3.0 Hz, JCPt ¼ 35.4 Hz, CArP),
2
136.1 (d, 1JCP ¼ 2.3 Hz, CArP), 136.1 (dd, 1JCP ¼ 2.3 Hz, 2JCPt ¼ 32.3 Hz,
6.2. Bis(triphenylphosphine)-(h
2-2-(diazo(phenyl)methyl)phenyl-
1
1
CArP), 137.3 (d, JCP ¼ 2.3 Hz, CArP), 137.3 (dd, JCP ¼ 2.3 Hz,
4-nitrocinnamate)platinum(0) ([1NO2]Pt)
2JCPt ¼ 28.9 Hz, CArP), 137.7 (d, JCP ¼ 2.3 Hz, CArP), 137.7 (dd,
1
1JCP ¼ 2.3 Hz, 2JCPt ¼ 27.7 Hz, CArP), 139.4 (CAr), 140.6 (bs, CArP), 140.8
Orange solid, yield: 90%, route B. 1H NMR (C6D6):
d
¼ 3.87 (dpt,
3
3
(bs, CArP), 144.7 (d, JCP ¼ 6.2 Hz, CArCH), 144.7 (dd, JCP ¼ 6.2 Hz,
3JHH ¼ 8.9 Hz, 3JHP ¼ 3.9 Hz, 3JHP ¼ 8.9 Hz, 1H, CHCHCO), 3.87 (ddpt,
2JCPt ¼ 33.1 Hz, CArCH), 150.8 (CArO), 170.9 (dd, JCP ¼ 2.3 Hz,
3
3
3
2
3JHH ¼ 8.9 Hz, JHP ¼ 3.9 Hz, JHP ¼ 8.9 Hz, JHPt ¼ 51.0 Hz, 1H,
3JCP ¼ 4.6 Hz, CHCOO), 170.9 (ddd, JCP ¼ 2.3 Hz, JCP ¼ 4.6 Hz,
3
3
CHCHCO), 4.23 (dpt, 3JHH ¼ 8.9 Hz, 3JHP ¼ 4.9 Hz, 3JHP ¼ 8.9 Hz, 1H,
2JCPt ¼ 46.9 Hz, CHCOO), 196.1 (CarCOCAr). 31P NMR (C6D6):
¼ 27.6
d
3
3
3
(d, 2JPP ¼ 40.6 Hz), 27.6 (dd, 2JPP ¼ 40.6 Hz, 1JPPt ¼ 4194.1 Hz), 28.5 (d,
C
ArCHCH), 4.23 (ddpt, JHH ¼ 8.9 Hz, JHP ¼ 4.9 Hz, JHP ¼ 8.9 Hz,
2JHPt ¼ 50.2 Hz, 1H, CArCHCH), 6.12 - 6.22 (m, 2H, HAr), 6.69e7.11 (m,
2JPP ¼ 40.6 Hz), 28.5 (dd, JPP ¼ 40.6 Hz, JPPt ¼ 3630.4 Hz). 195Pt
2
1
33H, HAr), 7.40e7.58 (m, 6H, HAr), 7.61e7.67 (m, 2H, HAr). 31P NMR
NMR (C6D6):
d
¼ ꢀ5038.1 (dd, 1JPPt ¼ 3630.4 Hz, 1JPPt ¼ 4195.8 Hz).
2
2
FAB-MS: m/z (%): 718.8 (100) [Pt(PPh3)(PPh2C6H4)þ]. ESI-MS: m/z
(C6D6):
d
¼ 25.8 (d, JPP ¼ 32.4 Hz), 25.8 (dd, JPP ¼ 32.4 Hz,
1JPPt ¼ 4045.2 Hz), 27.1 (d, 2JPP ¼ 32.4 Hz), 27.1 (dd, 2JPP ¼ 32.4 Hz,
1JPPt ¼ 3723.2 Hz). FT-IR (cmꢀ1): 3060 (w), 2045 (m, N2), 1702 (m,
CO), 1586 (m),1505 (m), 1479 (m), 1434 (m), 1330 (s), 1273 (w), 1180
(w), 1094 (s), 846 (w), 743 (m), 705 (s), 578 (w), 539 (w), 508 (s),
459 (w), 417 (w). UV/vis (pentane, nm): 208 (s, Ar), 276 (m, N2), 389
(m).
(%): 758.9 [Pt(PPh3)(PPh2C6H4)CH3CNþ]. elemental analysis for
C58H46O3P2Pt (1048.01 g/mol): calcd.: C 66.47, H 4.42, Pt 18.61
found: C 66.83, H 4.32.
6.4. Bis(triphenylphosphine)-(h
2-2-benzoylphenyl 4-nitrocinn
amate)platinum(0) [10NO2]Pt
6.3. Bis(triphenylphosphine)-(h
2-2-benzoylphenylcinnamate)pla
Yellow solid, yield: 85%, route: A. Single crystals suitable for X-
ray analysis were obtained by slow diffusion of pentane into a
tinum(0) ([10]Pt)
3
toluene solution. 1H NMR (C7D8):
d
¼ 3.33 (dpt, JHH ¼ 8.9 Hz,
Light yellow solid, yield: >99%, route A. 1H NMR (C6D6):
d
¼ 3.57
3JHP ¼ 4.4 Hz, 3JHP ¼ 8.9 Hz, 1H, CHCHCO), 3.33 (ddpt, 3JHH ¼ 8.9 Hz,
3JHP ¼ 4.4 Hz, 3JHP ¼ 8.9 Hz, 2JHPt ¼ 57.4 Hz, 1H, CHCHCO), 3.69 (dpt,
3JHH ¼ 8.9 Hz, 3JHP ¼ 4.8 Hz, 3JHP ¼ 8.9 Hz, 1H CArCHCH), 3.69 (ddpt,
(dpt, 3JHH ¼ 8.7 Hz, 3JHP ¼ 4.4 Hz, 3JHP ¼ 8.7 Hz, 1H, CHCHCO), 3.57
Ph3P
PPh3
O
3JHH ¼ 8.9 Hz, JHP ¼ 4.8 Hz, JHP ¼ 8.9 Hz, JHPt ¼ 50.2 Hz, 1H
3
3
2
Pt
C
ArCHCH), 5.96 (d, 3JHP ¼ 7.3 Hz, 2H, HAr), 6.64 (d, 3JHP ¼ 8.2 Hz, 1H,
HAr), 6.77e7.08 (m, 31H, HAr), 7.36e7.45 (m, 5H, HAr), 7.55 (d,
O
N2
3JHP ¼ 8.7 Hz, 2H, HAr), 7.82 (d, JHP ¼ 7.9 Hz, 2H, HAr). 31P NMR
3
[2NO2]Pt
2
2
(C7D8):
d
¼ 26.5 (d, JPP ¼ 32.0 Hz), 26.5 (dd, JPP ¼ 32.0 Hz,
O2N
1JPPt ¼ 4071.8 Hz), 27.7 (d, 2JPP ¼ 32.0 Hz), 27.7 (dd, 2JPP ¼ 32.0 Hz,
1JPPt ¼ 3703.3 Hz). FAB-MS: m/z (%): 719.1 (100) [Pt(PPh3)(PPh3)þ],
1092.2 (3.74) [C22H15NO5Pt(PPh3)(PPh3)þ]. elemental analysis for
Scheme 9.
Please cite this article in press as: M.R. Buchner, et al., Journal of Organometallic Chemistry (2013), http://dx.doi.org/10.1016/
j.jorganchem.2013.04.045

M.R. Buchner et al. / Journal of Organometallic Chemistry xxx (2013) 1e8
7
C58H45NO5P2Pt (1093.01 g/mol): calcd.: C 63.73, H 4.15, N 1.28
found: C 65.55, H 4.19, N 1.43.
3JHH ¼ 16.1 Hz, 1H, CHCHCO), 7.54e7.26 (m, 7H, HAr), 7.73 (d,
3JHH ¼ 8.7 Hz, 2H, HAr), 7.89 (d, 3JHH ¼ 16.1 Hz,1H, CArCHCH), 8.26 (d,
3JHH ¼ 8.6 Hz, 2H, HAr). FT-IR (KBr plates, cmꢀ1): 2962 (m), 2925 (s),
2850 (w), 2066 (s, N2), 1720 (s, CO), 1644 (m), 1599 (m), 1521 (m),
1450 (w), 1420 (w), 1345 (m), 1300 (w), 1270 (w), 1144 (m), 897 (w),
748 (m), 644 (w). UV/vis (pentane, nm): 210 (s, Ar), 260 (s, Ar), 285
(m, N2).
6.5. Bis(triphenylphosphine)-(
namate)platinum(0) ([2NO2]Pt)
h
2-9-diazofluoren-1-yl-4-nitrocin
Orange solid, yield: 91%, route B. 1H NMR (C6D6):
d
¼ 3.94 (dpt,
3JHH ¼ 9.1 Hz, 3JHP ¼ 3.7 Hz, 3JHP ¼ 9.1 Hz, 1H, CHCHCO), 3.94 (ddpt,
Light induced ligand exchange: 30.0
mmol diazo complex and
3
3
2
3JHH ¼ 9.1 Hz, JHP ¼ 3.7 Hz, JHP ¼ 9.1 Hz, JHPt ¼ 58.4 Hz, 1H,
30.0 mol triphenylphosphine were weighed into a J.-Young NMR
m
CHCHCO), 4.45 (dpt, 3JHH ¼ 9.1 Hz, 3JHP ¼ 4.1 Hz, 3JHP ¼ 9.1 Hz, 1H,
tube, dissolved in 0.5 ml benzene-d6 and irradiated at 300 nm for
the given amount of time.
3
3
3
C
ArCHCH), 4.45 (ddpt, JHH ¼ 9.1 Hz, JHP ¼ 4.1 Hz, JHP ¼ 9.1 Hz,
2JHPt ¼ 51.8 Hz, 1H, CArCHCH), 6.39 (d, 3JHH ¼ 7.8 Hz, 2H, HAr), 6.68e
Photo-gated oxidative addition: 9.00
weighed into a J.-Young NMR tube, dissolved in 0.5 ml C6D6,
9.90 mol silane or aryl halide was added via Hamilton-syringe and
mmol diazo complex was
7.03 (m, 24H, HAr), 7.04e7.17 (m, 7H, HAr), 7.48e7.59 (m, 6H, HAr),
7.69 (d, JHH ¼ 8.7 Hz, 2H, HAr). 31P NMR (C6D6):
d
¼ 26.1 (d,
m
3
2JPP ¼ 30.7 Hz), 26.1 (dd, 2JPP ¼ 30.7 Hz, 1JPPt ¼ 4073.5 Hz), 26.7 (d,
2JPP ¼ 30.7 Hz), 26.7 (dd, 2JPP ¼ 30.7 Hz, 1JPPt ¼ 3701.8 Hz). FAB-MS:
m/z (%): 719.0 (100) [Pt(PPh3)(PPh3)þ], 1074.8 (1.01)
[C22H13NO4Pt(PPh3)(PPh3)þ]. FT-IR (cmꢀ1): 3064 (w), 2965 (w),
2925 (w), 2859 (w), 2063 (s, N2), 1713 (s, CO), 1586 (m), 1519 (m),
1434 (m), 1424 (m), 1329 (s), 1303 (w), 1263 (m), 1178 (w), 1138 (w),
1093 (s), 1018 (w), 844 (w), 802 (m), 748 (s), 693 (s), 538 (m), 518
(s), 508 (s).
irradiated at 300 nm.
Hydrosilylation of p-fluoroacetophenone: 5.00 mmol catalyst and
65.0 ml (74.3 mg, 0.54 mmol, 1.0 eq.) p-fluoroacetophenone were
dissolved in 0.25 ml CD2Cl2 placed in a J.-Young NMR tube, 0.15 ml
(149.0 mg, 0.81 mmol, 1.5 eq.) Ph2SiH2 added and spectra recording
commenced.
Photo-gated catalysis: 7.39 mg (6.7
weighed into a septum NMR tube, 27.0
1.1 eq.) Ph2SiH2 and 16.6 l (16.1 mg, 134.0
m
mol, 5 mol%) complex was
l (26.8 mg, 145.0 mol,
mol, 1.0 eq.) aceto-
m
m
m
m
6.6. N0-(1-Hydroxy-9H-fluoren-9-ylidene)-4-methylbenzenesu
lfonohydrazide monohydrate
phenone dissolved in 0.4 ml benzene-d6 were added via syringe
through the septum, the tube shaken and irradiated at 300 nm for
the described time. Afterwards spectra recording was commenced.
1.00 g (5.10 mmol) 1-hydroxy-9-fluorenone, 1.41 g (7.57 mmol)
tosylhydrazone and 875 ml conc. hydrochloric acid were suspended
Acknowledgements
in 22 ml ethanol and refluxed over night. The reaction mixture was
cooled to ambient temperature and the solvent removed under
reduced pressure. The product was isolated by flash chromatog-
raphy (SiO2; CH2Cl2) as a white solid (0.82 g, 2.14 mmol, 42%). 1H
The authors thank the Institute for Silicon chemistry and
WACKER CHEMIE AG for financial support.
NMR (CDCl3):
d
¼ 1.54 (s, 2H, H2O), 2.42 (s, 3H, CArCH3), 6.78 (d,
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j.jorganchem.2013.04.045