Chemoselective Hydrogenation with Supported Organoplatinum(IV) Catalyst on Zn(II)-Modified Silica

Article abstract of DOI:10.1021/jacs.7b11981

Well-defined organoplatinum(IV) sites were grafted on a Zn(II)-modified SiO₂ support via surface organometallic chemistry in toluene at room temperature. Solid-state spectroscopies including XAS, DRIFTS, DRUV-vis, and solid-state (SS) NMR enhanced by dynamic nuclear polarization (DNP), as well as TPR-H₂ and TEM techniques revealed highly dispersed (methylcyclopentadienyl)methylplatinum(IV) sites on the surface ((MeCp)PtMe/Zn/SiO₂, 1). In addition, computational modeling suggests that the surface reaction of (MeCp)PtMe₃ with Zn(II)-modified SiO₂ support is thermodynamically favorable (ΔG = -12.4 kcal/mol), likely due to the increased acidity of the hydroxyl group, as indicated by NH₃-TPD and DNP-enhanced ¹⁷O{¹H} SSNMR. In situ DRIFTS and XAS hydrogenation experiments reveal the probable formation of a surface Pt(IV)-H upon hydrogenolysis of Pt-Me groups. The heterogenized organoplatinum(IV)-hydride sites catalyze the selective partial hydrogenation of 1,3-butadiene to butenes (up to 95%) and the reduction of nitrobenzene derivatives to anilines (up to 99%) with excellent tolerance of reduction-sensitive functional groups (olefin, carbonyl, nitrile, halogens) under mild reaction conditions.

Full text of DOI:10.1021/jacs.7b11981

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Article
Chemoselective Hydrogenation with Supported
Organoplatinum(IV) Catalyst on Zn(II)-Modified Silica
Jeffrey Camacho-Bunquin, Magali S. Ferrandon, Hyuntae Sohn, Dali Yang, Cong Liu, Patricia
Ignacio-de Leon, Frédéric A. Perras, Marek Pruski, Peter C. Stair, and Massimiliano Delferro
J. Am. Chem. Soc., Just Accepted Manuscript • DOI: 10.1021/jacs.7b11981 • Publication Date (Web): 27 Feb 2018
Downloaded from http://pubs.acs.org on February 27, 2018
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Journal of the American Chemical Society
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Chemoselective Hydrogenation with Supported
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Organoplatinum(IV) Catalyst on Zn(II)-Modified Silica
Jeffrey CamachoꢀBunquin,a* Magali Ferrandon,a Hyuntae Sohn,a Dali Yang,a Cong Liu,a Patricia
Anne Ignacioꢀde Leon,b Frédéric A. Perras,c Marek Pruski,c,d Peter C. Stair a,e* and Massimiliano
Delferroa*
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aChemical Sciences and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois
60439, United States
bEnergy Sciences Division, Argonne National Laboratory, 9700 S Cass Avenue, Lemont, Illinois 60439, United
States
cAmes Laboratory, U.S. Department of Energy, Ames, Iowa, 50010, United States
dDepartment of Chemistry, Iowa State University, 2416 Pammel Drive, Ames, Iowa, 50011, United States
eDepartment of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
ABSTRACT: Wellꢀdefined organoplatinum(IV) sites were grafted on a Zn(II)ꢀmodified SiO2 support via surface organometallic
chemistry in toluene at room temperature. Solidꢀstate spectroscopies including XAS, DRIFTS, DRUVꢀVis, and solidꢀstate (SS)
NMR enhanced by dynamic nuclear polarization (DNP), as well as TPRꢀH2 and TEM techniques revealed highly dispersed
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(methylcyclopentadienyl)methylplatinum(IV) sites on the surface ((MeCp)PtMe/Zn/SiO2, 1). In addition, computational modelling
suggests that the surface reaction of (MeCp)PtMe3 with Zn(II)ꢀmodified SiO2 support is thermodynamically favorable (∆G = ꢀ12.4
kcal/mol), likely due to the increased acidity of the hydroxyl group, as indicated by NH3ꢀTPD and DNPꢀenhanced 17O{1H}
SSNMR. In situ DRIFTS and XAS hydrogenation experiments reveal the likely formation of a surface Pt(IV)ꢀH upon hydrogenolyꢀ
sis of PtꢀMe groups. The heterogenized organoplatinum(IV)ꢀhydride sites catalyze the selective partial hydrogenation of 1,3ꢀ
butadiene to butenes (up to 95%) and the reduction of nitrobenzene derivatives to anilines (up to 99%) with excellent tolerance of
reductionꢀsensitive functional groups (olefin, carbonyl, nitrile, halogens) under mild reaction conditions.
Introduction
Chemoselective catalytic hydrogenation plays an imꢀ
Corma and coworkers9 recently demonstrated that downꢀ
sizing of supported Pt sites from nanoparticles to highly disꢀ
persed clusters or singleꢀatom catalytic sites in a Pt/FeOx sysꢀ
tem resulted in catalytic materials with unprecedented reactiviꢀ
ty and enhanced selectivity for hydrogenation of polyꢀ
functionalized nitroꢀaromatics to the aromatic amines. The
Pt/FeOx systems were synthesized via coꢀprecipitation of noꢀ
ble metals with bulk, lowꢀsurfaceꢀarea metal oxides (FeOx),4b,
10 resulting in some of the Pt sites entrapped in the bulk of the
material. Additionally, the low surface area of these systems
can limit the number of accessible catalytic surface sites. Conꢀ
ceivably, highꢀsurfaceꢀarea oxides, such as silica, comprise a
promising class of supports for isolated noble metal catalysts.
The low acidity and weak interaction of SiO2 with noble metꢀ
als, however, render such a support less effective in stabilizing
noble metal active sites.
portant role for the production of fine chemicals.1 In particular,
the chemoselective hydrogenation of functionalized nitroꢀ
aromatics to aromatic amines is an industrially important
transformation, principally in the agrochemical, pigment and
pharmaceutical industries.2 Catalysts that preferentially reduce
nitro groups and are tolerant of other hydrogenationꢀsensitive
functionalities, such as C=C and C=O groups, are desired for
this chemistry. Current industrial strategies for the reduction
of nitroꢀaromatics employ stoichiometric quantities of reducꢀ
ing agents (e.g., sodium hydrosulfide, iron, tin or zinc in amꢀ
monium hydroxide),3 and noble metal hydrogenation catalysts
(e.g., Pb–Pt/CaCO3, Pt/C)4 in the presence of transition metal
additives (e.g., Fe and V salts).4b, 5 Additiveꢀfree and recyclaꢀ
ble nitroꢀaromatic hydrogenation catalysts recently became
available after the development of supported Au nanoparticles
on oxides such as TiO2 and Fe2O3,4b Au alloys with hydroꢀ
genationꢀactive metals such as Pd or Pt,6 transition metal naꢀ
noparticles such as Pt, Ru or Ni,6ꢀ7 and singleꢀatom noble metꢀ
al catalysts (e.g., Pt/FeOx).4 With the everꢀincreasing cost of
noble metals and their fairly low natural abundance, additiveꢀ
free, atomꢀefficient and recyclable catalyst strategies will enꢀ
sure the longꢀterm sustainability of this industrial catalytic
process.8
Surface organometallic chemistry (SOMC)11,12,13,14,15 repꢀ
resents an alternative synthetic strategy for the controlled depꢀ
osition of highlyꢀdispersed, singleꢀsite catalysts on traditional
highꢀsurfaceꢀarea supports. Over the past few decades, SOMC
has been employed in the synthesis of oxideꢀsupported metalꢀ
lic catalysts for chemoselective hydrogenation of a range of
unsaturated organics such as alkenes, carbonyls and α,βꢀ
unsaturated carbonyls.14g, 16 The reactivity of surface organoꢀ
metallic catalytic sites can be tuned/influenced by ancillary
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Page 2 of 14
resulting (MeCp)PtMe/Zn/SiO (1) solid was then washed with
ligands and/or metalꢀhydrocarbyl moieties, with the latter purꢀ
posefully incorporated as a convenient entry into the target
catalytic cycle via activation under reducing conditions.17
Here we report the design, synthesis and characterization
of a supported organoplatinum catalyst for selective hydroꢀ
genation of organic substrates, where isolated organoplatiꢀ
num(IV) sites were deposited on a Zn(II)ꢀmodified SiO2 surꢀ
face via SOMC. The synthetic approach involves the installaꢀ
tion of a submonolayer of Zn2+ anchoring sites on SiO2 to staꢀ
bilize highly dispersed organoplatinum(IV) fragments. In this
system, the Pt4+ sites are bound to the surface, predominantly
in a bipodal fashion and stabilized by the methylcyclopentadiꢀ
enyl ligand and one methyl group ((MeCp)PtMe/Zn/SiO2, 1).
The hydrogenolysis of 1 leads to the likely formation of a
catalytically active organoplatinum(IV) hydride species,
((MeCp)PtH/Zn/SiO2, 2), as observed by in situ infrared specꢀ
troscopy. The resulting Pt4+/Zn2+/SiO2 catalyst exhibits hydroꢀ
genation activity well differentiated from its PtZn/SiO2 nanoꢀ
particle counterparts;18 catalyst 2 semiꢀhydrogenates 1,3ꢀ
butadiene to mixtures of butenes, and chemoselectively hyꢀ
drodeoxygenates a range of functionalized nitroꢀaromatics to
the corresponding anilines, under mild conditions. Investigaꢀ
tion of the effects of catalyst activation conditions revealed
that hydrogenolysis of the (MeCp)ꢀPt linkage is detrimental to
the hydrogenation selectivity, confirming that supported orꢀ
ganoplatinum active species are responsible for the chemoseꢀ
lective catalysis.
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two 10 mL portions of toluene and was dried under vacuum.
The metal loading of 1 product was determined by ICPꢀOES:
Pt = 0.2 % (w/w), Zn = 10%. For the catalysis experiments
described below, preꢀcatalyst 1 is activated with H2 over a
range of temperatures. Activation at a temperature of 135 °C
results in an active hydrogenation catalyst 2.
Synthesis of PtZn/SiO2 (nanoparticles) Catalyst (3). The asꢀ
prepared (MeCp)PtMe/Zn/SiO (1) was loaded in a tube furꢀ
nace, dried at 150 °C for 2 h, and then calcined with a flow of
air at 550 °C for 4 h.
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Physical and Analytical Measurements. Elemental analysis
(Pt, Zn) was conducted by Galbraith Laboratories, Inc. (Knoxꢀ
ville, TN). Temperatureꢀprogrammed reduction (TPRꢀH2) and
ammoniaꢀtemperature programmed desorption (NH3ꢀTPD)
were performed on an Altamira catalyst characterization
instrument (model: AMIꢀ200ꢀMR). For TPRꢀH2, 40 mg of 1
was first measured and transferred into a quartz tube forming a
catalyst bed. The quartz reactor was then centered inside a labꢀ
scale furnace. A thermocouple was attached at the inlet of the
reactor having a close contact with the sample to measure the
actual temperature of the catalyst bed. The outlet of the reactor
was connected to a thermal conductivity detector (TCD)
followed by a Dycor Benchtop Mass Spectrometer (AMETEK
Process Instrument). A gas mixture of 3% H2/Ar was
introduced to the reactor at 30 mL/min while the reactor
temperature was increased from RT to 600 °C with a ramp rate
of 10 °C/min. The TCD and mass spectrometer signals were
collected continuously (m/z = 2 to 50) during the reaction.
Similarly, the NH3ꢀTPD experiment was conducted using 1%
NH3/Ar gas. The sample was first treated with pure Ar at
200 °C for 60 min. The temperature was then decreased to
100 °C and 1% NH3/Ar was introduced to the reactor for 60
min to adsorb NH3 on the catalyst surface. The NH3 desorption
was performed by increasing the reactor temperature from
100 °C to 650 °C at a ramp rate of 10 °C/min and held at
650 °C for 60 min. The exhaust stream from the reactor was
analyzed by both TCD and mass spectrometer (m/z = 16, 17)
detectors.
Diffuse reflectance infrared Fourier transform spectrosꢀ
copy (DRIFTS) was acquired using a Thermo Scientific™
Nicolet iS50 FTꢀIR spectrometer equipped with an iS50 Auꢀ
tomated Beam splitter exchanger (ABX). Preꢀcatalyst 1 was
finely ground and placed on a sample holder inside a high
temperature reaction chamber (Praying Mantis™). The
DRIFTS spectra of preꢀcatalyst 1 were collected at RT under
He and at 100 °C and 150 °C under reducing conditions (H2)
using 30 mL/min of 3% H2/He. A spectrum of SiO2 was
obtained separately and was used as a background for all three
temperatures. The detection of PtꢀH was carried out using the
same reactor. For this experiment, preꢀcatalyst 1 with higher
Pt loading (1% w/w) was employed in order to match the deꢀ
tection level of the DRIFTS instrument. The tested sample was
not exposed to air after Pt grafting on Zn/SiO2 to reduce the
undesirable interference from water. First, a background specꢀ
trum was collected after purging preꢀcatalyst 1 at RT for 10
min with He at 30 mL/min. The sample was then exposed to
30 mL/min of pure H2 at RT for 30 min. After a spectrum was
collected, which served as the background for subsequent
measurements, the reactor temperature was increased to 50 °C,
100 °C, 135 °C and 150 °C. At each temperature, the sample
was treated with pure H2 for 30 min (30 mL/min) and a specꢀ
Experimental Section
Materials and Methods. All manipulations of airꢀsensitive
materials were performed with rigorous exclusion of O2 and
moisture in ovenꢀdried Schlenkꢀtype glassware on a dual manꢀ
ifold Schlenk line or in a N2ꢀfilled MBraun glovebox with a
highꢀcapacity recirculator (<1 ppm O2), unless noted otherwise.
Silica
(Davisil
646,
40−50
mesh,
300
m2/g),
methylcyclopentadienyltrimethylplatinum(IV) and diethyl zinc
were used as received (SigmaꢀAldrich). All gases (1% 1,3ꢀ
butadiene/He, 10% H2/N2, 100% H2, and N2) were purchased
from Airgas as UHP grade and had oxygen and moisture traps.
Solid substrates, 2ꢀnitrobenzaldehyde, 4ꢀnitrobenzaldehyde, 4ꢀ
nitrobenzophenone,
methyl
4ꢀnitrobenzoate,
4ꢀ
nitrobenzonitrile, and 2ꢀchloronitrobenzene, were purchased
from SigmaꢀAldrich and dried in a flask with a Teflon
stopcock under vacuum at ambient temperature for 16 h before
use. Liquid substrates such as 3ꢀnitrostyrene, 4ꢀnitrostyrene,
and nitrobenzene, were purchased from SigmaꢀAldrich and
sparged with N2 for an hour prior to use. Dodecane (Sigmaꢀ
Aldrich) was sparged with nitrogen and dried over activated
alumina.
Synthesis
of
(MeCp)PtMe/Zn/SiO2
(1)
and
(MeCp)PtH/Zn/SiO2 (2) Materials. Zn2+ was installed on
SiO2 via atomic layer deposition (ALD) using an
ARRADIANCE Integrated ALDꢀCatalysis tool (model ARRꢀ
100000 GEMSTARꢀCAT Dual System)19 according the
literature procedure20 (10% w/w; 75% of a theoretical monoꢀ
layer; see also Supporting Information). A 40 mL scintillation
vial was charged with a slurry of 2.0 g Zn/SiO2 in 10 mL toluꢀ
ene. A 20 mL toluene solution of [(MeCp)PtMe3] (390 mg,
1.22 mmol Pt) was added dropꢀwise to the stirring slurry of
Zn/SiO2 over 30 minutes. The reaction mixture was stirred for
24 h, the stirring stopped, and the resulting solids filtered. The
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requires 5.3 kcal/mol energy at room temperature,
trum was obtained. Identical experimental procedures were
a
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followed to observe PtꢀD employing a pure D2 gas at 30
mL/min. Lastly, the spectrum of CO adsorbed on 1 was
recorded before and after H2 reduction first at 100 °C and then
at 200 °C. The experimental procedure was as follows: 1) the
reactor cell was flushed with He at 30 mL/min while the
temperature of the reactor cell was increased from RT to 40 °C.
2) A background spectrum of 1 was collected at 40 °C after
flushing for 10 min in He. 3) The sample was then treated with
10% CO/He at 30 mL/min for 1 h and a spectrum was
collected. 4) Another spectrum was recorded after flushing
with He for 10 min. For H2 treated samples, 30 mL/min of 3%
H2/He gas was introduced to the reactor cell at 100 °C or
200 °C for 1 h and then cooled down to RT in He prior to step
1).
The diffuse reflectance ultravioletꢀvisible (DRUVꢀVis)
spectra were obtained on a Shimadzu UVꢀ3600 Plus spectroꢀ
photometer using a photomultiplier tube (PMT) detector. The
samples were first finely ground and placed on a cup holder
where the beam was aligned at the center. The measurement
was done using a medium scan speed, 1 nm sampling interval
and a slit width of 3 nm. Two reference spectra of
polytetrafluoroethylene (PTFE) and SiO2 were collected from
200 to 700 nm and used as backgrounds (Rref). The obtained
sample spectra were transformed to KubelkaꢀMunk (KꢀM) and
Tauc functions using the equation F(R∞)=(1ꢀR1)2/2×R1 where
R∞ denotes KꢀM function and R1=Rsample/Rref. All the samples
were diluted using SiO2 to reduce the KꢀM intensity below 1.5.
The dilution was carried out in order to eliminate nonlinearity
while collecting the spectra.
A JEOL JEMꢀ2100F transmission electron microscope
(TEM) was used for all bright field (BF) imaging at 200 kV.
Samples were prepared by dispersing solids in ethanol via
sonication for 30 s. Colloidal suspensions were drop cast onto
lacey C on Cu grids (300 mesh) from Electron Microscopy
Sciences.
The crystalline phase compositions of spent catalyst 2 (afꢀ
ter 24 h reaction at 75 °C in 0.25 M nitrobenzene with 200 psi
H2) were determined by powder Xꢀray diffraction (PXRD)
using a Bruker Diffractometer D8 Advance operating with the
following parameters: Cu Kα radiation of 40 mA, 40 kV, Kλ =
0.15418 nm, 2θ scanning range of 10ꢀ70°, a scan step size of
0.0018º and a time of 1s per step. The sample was ground and
placed on a zero background silicon holder (MTI Corp.) for
analysis.
suggesting that Zn/SiO2ꢀ1 is thermodynamically more stable
and more likely to exist at room temperature. The bottom half
of the clusters (11 O, 6 H and 6 Si atoms) were kept frozen
during the geometry optimizations while the top half and the
interacting molecules were allowed to relax.
Solid-state NMR Spectroscopy. All solidꢀstate (SS) NMR
experiments were performed on naturalꢀabundance samples,
using a Bruker AVANCE III 400 spectrometer, operated at 9.4
T, equipped with a 9.7 T gyrotron for dynamic nuclear polariꢀ
zation (DNP) measurements as well as 3.2ꢀmm lowꢀ
temperature magicꢀangleꢀspinning (MAS) probe. For DNP, the
samples were first impregnated with a 16 mM solution of
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1
TEKPol in 1,1,2,2ꢀtetrachloroethane (TCE), with natural H
abundance (for 195Pt and 17O measurements) or 99.6% deuterꢀ
ated (for 13C measurements), and then packed into 3.2ꢀmm
sapphire rotors.25 The MAS frequency was set to either 12.5
kHz (17O, 195Pt), 12 kHz (13C), or 0 kHz (195Pt, a static measꢀ
urement) and the sample temperature was approximately ꢀ
163 °C under MAS and ꢀ148 °C under the static condition.
The 1Hꢀ17O distance measurements were carried out using
a DNPꢀenhanced 17O{1H} windowedꢀprotonꢀdetected local
field (wPDLF)26 technique with quadrupolar Carr Purcell
Meiboom Gill (QCPMG)27 acquisition scheme. The wPDLF
sequence was used as previously published,26, 28 with wR182
5
recoupling (50% window) for the distance measurement and
7
R181 for PRESTO population transfer (PRESTO = phaseꢀ
shifted recoupling effects a smooth transfer of order).29 The
17O centralꢀtransitionꢀselective 90° and 180° pulses lasted 5
and 10 ꢁs, respectively, and the QCPMG spikelet separation
was set to 6.25 kHz. 800 scans were accumulated for each t1
increment of a single recoupling block and a total of 20 increꢀ
ments were acquired.
The 13C CPMAS spectrum of catalyst 1 was acquired usꢀ
ing a CP (crossꢀpolarzation) contact time of 250 ꢁs; the 1H and
13C 90° pulses both lasted 3 ꢁs and 4096 scans were accumuꢀ
lated using a relaxation delay of 1 s. Two 13C{1H} HETCOR
spectra were acquired using contact times of 100 and 4000 ꢁs.
Frequencyꢀswitched LeeꢀGoldburg homonuclear decoupling30
was applied in t1 to improve the resolution and a total of 18
increments of 33 ꢁs, each consisting of 1024 scans, were acꢀ
quired using the StatesꢀTPPI method.
The DNPꢀenhanced 195Pt spectra were acquired using the
standard 195Pt CPMAS and the static wideline BCPꢀWCPMG
1
experiment, consisting of broadband adiabatic inversion Hꢀ
195Pt CP (BRAINꢀCP)31, which incorporates wideband uniform
rate and smooth truncation (WURST)32 pulses for spin inverꢀ
sion and CPMG refocusing.33 The 195Pt CPMAS spectrum was
acquired using a CPꢀecho sequence in which the contact time
Computational Details. All the calculations were carried out
using B3LYP functional21 with a CEPꢀ31G basis set22 as
available for the E.01 version of the Gaussian09 program.23
Calculations were used to investigate the thermodynamic of
the first PtꢀMe protonolysis reaction with isolated surface hyꢀ
droxyl in order to elucidate the ability of Zn/SiO2 to stabilize
the molecular organoplatinum sites. A cluster model of the
SiO2 support with six silica rings (Figure S3a) was used based
on our previous computational study.24 This cluster model was
shown to be sufficient to model the amorphous silica. A single
Zn2+ site was created on the silica cluster to mimic the
anchoring sites of Zn/SiO2 (Figure S3b). Two possible
configurations of Zn/SiO2 were considered: a 3ꢀcoordinate
Zn2+ site (Zn/SiO2ꢀ1, Figure S3b) and a 4ꢀcoordinate
hydroxylated Zn2+ site (Zn/SiO2ꢀ2, Figure S3c) to account for
the interaction of Zn/SiO2ꢀ1 with a water molecule. It is
notable that the formation of Zn/SiO2ꢀ2 from Zn/SiO2ꢀ1
1
was set to 5 ms and the refocusing pulse lasted 9 ꢁs. The H
excitation pulse lasted 2.75 ꢁs and total of 3072 scans were
accumulated with a 4 s recycle delay. The BCPꢀWCPMG
spectrum was acquired using again a contact time of 5 ms
during which a WURST adiabatic pulse sweeping over 250
kHz was applied to 195Pt. For the WCPMG detection 50 ꢁs
WURST pulses sweeping over 500 kHz were used and the
1
spikelet separation was set to 5 kHz. The H excitation pulse
lasted 2.75 ꢁs and total of 2600 scans were accumulated with a
4 s recycle delay. In the case of the molecular precursor, only
64 scans were needed. Both the static and MAS spectra were
simulated using WSolids.
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X-ray Absorption Spectroscopy (XAS). Xꢀray absorption at 135 ºC for 30 min. The CM3 performed solid and liquid
1
near edge structure (XANES) and extended Xꢀray absorption
fine structure (EXAFS) measurements were carried out at the
bendingꢀmagnet beamline of the Materials Research Collaboꢀ
rative Access Team (MRꢀCAT) at the Advanced Photon
Source (APS) of Argonne National Laboratory. The Xꢀray
beam was calibrated to the Pt L3ꢀ and Zn Kꢀedges using Pt
and Zn foils at 11.564 keV (Pt L3 edge) and 9.659 keV (Zn K
edge). All XAS measurements were taken in the transmission
mode with ionization chambers optimized for the maximum
current with linear response (∼1010 photons detected/s). A
cryogenically water cooled doubleꢀcrystal Si(111) monoꢀ
chromator with a resolution better than 2.5 eV at 10 keV was
used. With respect to sample preparation, the weight ratios of
samples to boron nitride were first calculated to achieve an
edge step corresponding around 1ꢀ1.5 total absorbance unit for
all samples and standards. The samples were then mixed with
boron nitride and finely ground using a mortar and pestle. 5ꢀ10
mg of the mixture was placed into a sixꢀwell sample holder
where the radius of each well is around 2.0 mm. The sample
was pressed as a pellet, completely blocking the well, such
that the flow of gases could only pass through the pellet. The
sample holder was then inserted into a quartz tube (1–in. OD,
10–in. length) which was centered at the furnace and sealed
with Kapton windows by two UltraꢀTorr fittings. For in situ
XAS experiments, 50 mL/min of 3% H2/He was introduced to
the sample tube and the temperature of the furnace was inꢀ
creased to 135 and 200 °C. The EXAFS spectra for highꢀ
temperatureꢀtreated samples were taken after the reactor was
cooled down to RT under the H2 environment. Background
removal and normalization procedures were carried out using
the Athena software package (version 0.9.24) using standard
methods. Standard procedures based on Artemis software were
used to extract the EXAFS data. The coordination parameters
were obtained by a least square fit in Rꢀspace of the nearest
neighbour, k2ꢀweighted Fourier transform data (Figure S7).
dispensing. The catalysts were dispensed through disposable
shaker vials (SV) with polytetrafluoroethylene (PTFE)
hoppers and weighed using an automated balance (± 0.2 mg
accuracy). 750 µL of a 0.25 M stock solutions of each of the
substrates were used for the hydrogenation experiments. Each
solution was dispensed using a Rainin dispense tool equipped
with a disposable, 1ꢀmL positive displacement tip (PDT),
operated by the CM3. The multiꢀwell plate with vials was then
covered with a pinꢀhole Teflon gasket and a stainless steel pinꢀ
hole plate to ensure gas diffusion but to minimize crossꢀ
contamination between the vials. The multiꢀwell plate was
then transferred into a clamꢀshell reactor, which was sealed
inside the glovebox. The clamꢀshell reactor was then taken out
to the SPR, which is designed to carry out pressure reactions
with heating and orbital shaking. Initially, the SPR was
flushed with 500 mL/min H2 for 15 min at room temperature,
pressurized, and set to shake at 300 rpm. The reactor was then
heated up slowly (1 ºC/min ramp rate) to 40 ºC. Under the
given conditions, the pressure of the reactor reached 45 psi.
After 24 h, the shaking was stopped, the reactor was cooled
down to room temperature, and was flushed with 100 mL/min
N2 for 15 min. The clamꢀshell reactor was then brought back
to the glovebox. Aliquots were then transferred into filter vials
(Whatman MiniꢀUniPrep Syringeless Filter, 0.2 um) to
separate the solid catalysts from the organic solution and
protect the GC columns.
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Nitro-Aromatic Hydrogenation with a Homogeneous Or-
ganoplatinum(IV) Catalyst. 0.5 mg of Pt precursor
[(MeCp)PtMe3] was used for determining whether the molecuꢀ
lar analogue is also catalytically active. The following reaction
conditions were used in the SPR (vide supra): 750 µL of a
0.25 M stock solution of nitrobenzene, 75 ºC, 45 psi H2, 24 h.
No conversion was observed.
Recycling Experiment. A series of catalyst recyclability tests
were carried out with nitrobenzene as test substrate. Two samꢀ
ples of 30 mg of catalyst 2 were used with 0.75 mL of 0.25 M
nitrobenzene in toluene. After the first reaction (75 °C, 200 psi
H2, 24 h), the supernatants were removed carefully and set
aside for GC analyses. The “wet” catalysts were then rinsed
with a fresh solution of nitrobenzene in toluene. This was reꢀ
peated twice, before adding a fresh solution. Three consecuꢀ
tive runs were performed.
Catalytic Hydrogenation of 1,3-Butadiene. A 16ꢀchannel
highꢀthroughput fixed bed system (Flowrence® from
Avantium) was used for the catalytic experiments. 10 to 80 mg
catalyst was mixed with 100 mg Davisil Silica and loaded into
a quartz reactor (2 mm ID, 30 mm length). For 1,3ꢀbutadiene
hydrogenation, a total flowrate of 20.31 mL/min was used per
reactor of which 18.75 mL/min 1% 1,3ꢀbutadiene/Ar, 0.56
mL/min H2, and 1 mL/min He as internal standard. The
temperatures tested were 50 to 200 °C (5 °C/min) with an
increment of 25 °C. At each temperature, a gas sample was
taken automatically, sequentially from reactor #1 to reactor
#16, for gas chromatography analysis.
Leaching Test. 30 mg of catalyst 2 was used with 0.75 mL of
0.25 M nitrobenzene in toluene. The first reaction (75 °C, 200
psi H2) was carried out for 1 h; then the supernatant was reꢀ
moved carefully and spilt into 2 samples, one for GC analyses
and one for further reaction. The initial conversion after 1 h
was 91%. The remaining supernatant was then exposed to 200
psi H2 for 23 h at 75 °C.
Catalytic Hydrogenation of Nitro-Aromatics. An automated
synthesis platform (Core Module 3, CM3, Unchained Labs
Inc.) that is located in a customꢀbuilt N2ꢀfilled glovebox (MB
200B, MBraun) and a Screening Pressure Reactor (SPR,
Unchained Labs Inc.) in Argonne National Laboratory’s Highꢀ
throughput Research Facility, were used for the highꢀ
throughput experiments. Matrices of experiments and
protocols were designed in Library Studio while Automation
Studio (LEA software) was used for running the protocols.
Simultaneous testing of all the catalysts and controls were
carried out in multiꢀwell plates that can hold 48 2ꢀmL glass
vials per run. In every catalysis run, negative controls were
implemented using the thermal sample and the metalꢀfree siliꢀ
ca. The solid catalysts were preꢀreduced in 10% H2/N2 mixture
Real-time Monitoring of the Reduction of Nitrobenzene.
For kinetic measurements, the Optimization Screening Reactor
(OSR, Unchained Labs Inc.) located in the N2ꢀfilled glovebox,
was used. It has 8 parallel batch reactors with independent
temperature and pressure control and a common overhead
stirring, with the capability of sampling during reaction. First,
catalyst 2 (50, 100 or 200 mg) was loaded manually. Then, a
25 mL stock solution (either 0.125, 0.25 or 0.50 M
nitrobenzene in toluene) with 1,3,5ꢀtrimethylbenzene as
internal standard, was added, also manually. The rest of the
procedure was controlled
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Scheme 1. Solutionꢀphase synthesis of highly dispersed organoplatinum(IV) sites on a Zn/SiO2 support with (MeCp)PtMe3 in toluene at
room temperature (1) and hydrogenolysis of 1 to form 2 at 135 °C under an atmosphere of H2.
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by the LEA software; the reactors were purged with N2 twice
and then heated to various temperatures (60, 75 or 90 ºC),
flushed twice and pressurized with H2 (UHP grade, oxygen
and moisture trapped) up to various pressures (100, 200 or 300
psi). Stirring was set at 250 rpm, with a settling delay of 15 s
prior to sampling to avoid carrying over catalyst powder.
Automated sampling of 100 µL was performed at various
times, and dispened into vials (Whatman MiniꢀUniPrep
Syringeless Filter, 0.2 um), on a 48 well plate, preloaded with
100 µL of dodecane.
rower, yielding the longer average O–H bond length of 1.034
± 0.007 Å, compared to 1.022 ± 0.006 Å for the silica, which
indeed corroborates higher Brønsted acidity for Zn/SiO2.
GC-MS and GC-FID Analyses. The compositions of the
reaction mixtures were determined using a Trace GC Ultra
Gas Chromatograph system equipped with a Tri Plus RSH
autosampler, an ISQ MS detector, and a FID (Thermo
Scientific). The column used for the MS detector was an
Agilent J&W DBꢀ5 column (30 m × 0.25 mm × 0.25ꢁm film
thickness) while the column used for the FID was an Agilent
J&W DBꢀ5MS column (30 m × 0.25 mm × 0.25ꢁm film
thickness). GC data were analyzed using the Thermo Xcalibur
2.2 SP1.48 software. The following method was used: a 0.5
µL split injection with a split ratio of 100 run under a constant
gas flow of 1 mL/min. The oven temperature profile was as
follows: initial temperature = 30 °C, hold for 10 minutes, ramp
at 20 °C/min, final temperature = 250 °C.
Figure 1. (a) Overlaid 17O{1H} wPDLFꢀQCPMG spectra of SiO2
and Zn/SiO2. (b) An enlarged view of the higherꢀfrequency peak
is shown on the right with the lowerꢀfrequency peak set to 0 Hz in
order to highlight the splitting. A dashed red line marks the center
of the peak in SiO2 in order to ease the comparison of the two
spectra.
Results and Discussion
Synthesis of the Supported Organoplatinum Catalyst. Orꢀ
ganoplatinum(IV) sites were installed by solutionꢀphase
SOMC on highꢀsurfaceꢀarea SiO2 modified via ALD19ꢀ20 with
Zn2+ anchoring sites (Scheme 1). Based on the Zn loading
(10% w/w; 75% of a theoretical Zn2+ monolayer), the Zn/SiO2
support contains both isolated Zn2+ sites and ZnOꢀrich areas
(see NH3ꢀTPD trace in Figure S2). However, only surface
hydroxyls associated with isolated Zn2+ have increased acidity,
rendering the Zn/SiO2 system more capable of stabilizing Pt4+
sites, relative to traditional SiO2. Recent studies have shown
that the OꢀH bond lengths of surface hydroxyl groups, as
measured by DNPꢀenhanced 17O{1H} wPDLFꢀQCPMG experꢀ
iments, correlate strongly with the Brønsted acidity of these
groups.28 Specifically, the more Brønsted acidic surfaces were
found to have the longer average OꢀH bond lengths. Thus, in
order to obtain an independent confirmation that the Zn/SiO2
support is indeed more Brønsted acidic, 17O{1H} wPDLFꢀ
QCPMG spectrum was acquired and compared it with the
untreated SiO2 (Figure 1). As can be seen in Figure 1, the
dipolar splitting for the Zn/SiO2 material is qualitatively narꢀ
Figure 2. DFT calculations of the reaction free energies of
[(MeCp)PtMe3] reacting with a hydroxyl group (highlighted) on
(a) SiO2 and (b) Zn/SiO2 using cluster models of silica (method:
B3LYP/CEPꢀ31G). Blue, light blue, grey, light gray, yellow, and
red spheres represent Si, Zn, C, H, Pt, and O, respectively.
Solutionꢀphase organoplatination of Zn/SiO2 with molecꢀ
ular [(MeCp)PtMe3] precursor in toluene at room temperature
yields an airꢀstable (confirmed by XAS, vide infra), white,
solid product [(MeCp)PtMe(0.2% w/w)/Zn(10% w/w)/SiO2]
(1). Under identical conditions, organoplatination of SiO2 with
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experiments were used to further confirm these assignments.
[(MeCp)PtMe3] does not occur, thus, confirming the proposed
effect of Zn2+ on surface hydroxyl acidity and reactivity. DFT
calculations were performed to investigate the reactivity of
SiO2 and Zn/SiO2 with the molecular precursor
[(MeCp)PtMe3] at room temperature. These calculations illusꢀ
trate the thermodynamics of the initial grafting reaction of the
Pt complex onto the support. Computed thermodynamics of
the first PtꢀMe protonolysis event showed that the reaction
between [(MeCp)PtMe3] and the hydroxyl groups on SiO2 is
likely to be reversible, with a reaction free energy of ꢀ0.9
kcal/mol at room temperature (Figure 2a). In comparison, the
corresponding reaction with a bridgeꢀcoordinated hydroxyl
group of the Zn/SiO2 support is thermodynamically more faꢀ
vorable (∆G = ꢀ12.4 kcal/mol, Figure 2b), presumably due to
the increased acidity of the hydroxyl group (Brønsted acid
site) bridging a Zn and a Si center. In addition, we also invesꢀ
tigated the reactivity of a Zn(II)ꢀbound hydroxyl group on
Zn/SiO2 (Zn/SiO2ꢀ2 in Figure S3c), which is relatively less
stable (5.3 kcal/mol higher) than Zn/SiO2ꢀ1 (Figure 2b) at
room temperature. The calculations indicated that the reactiviꢀ
ty of Zn/SiO2ꢀ2 with [(MeCp)PtMe3] is consistently more faꢀ
vorable than SiO2 (See Figure S4). These results support the
experimental observations that at room temperature, solutionꢀ
phase Pt deposition is more favorable on Zn/SiO2 than on
SiO2.
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As can clearly be seen in Figure 4a, when a short CP contact
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Structural Characterization of the Supported Organoplat-
inum Catalyst. Results of a combination of solidꢀstate characꢀ
terization techniques (TPRꢀH2, TEM imaging) and spectroꢀ
scopic methods, including XAS, DNPꢀenhanced multinuclear
SS NMR, DRIFTS and DRUVꢀVis revealed that the Pt sites in
1 are predominantly at the tetravalent state, bound on dianionꢀ
ic siloxy sites, and are stabilized by anionic hydrocarbyl
groups such as methylcyclopentadienyl and methyl ligands
(Scheme 1). Previously reported Zn Kꢀedge XAS studies of Zn
deposition on SiO2 via ALD20 and strong electrostatic adsorpꢀ
tion (SEA)34 revealed the singleꢀsite nature of triꢀcoordinate
Zn2+ centers on the surface (Figure S5, Table S1). Platinum
L3ꢀedge XAS (Figure 3) was employed to elucidate the elecꢀ
tronic structure and coordination environment of Pt in 1.
XANES (Figure 3a) confirmed tetravalent state of the Pt cenꢀ
ters based on the edge absorption energy at 11566.6 eV (the
same value was obtained for tetravalent molecular precursor
[(MeCp)PtMe3]) and similar white line intensity. The EXAFS
spectrum of 1 (Figure 3b and Table 1) proposed a Pt coordinaꢀ
tion very similar to that of [(MeCp)PtMe3]: i) three coordinaꢀ
tion units at the Pt–O/C scattering path (2.02 ±0.02 Å) and ii)
five coordination units at the MeCpꢀPt bond distance (2.30
±0.02 Å); the latter suggests that the MeCpꢀPt moiety remains
intact after the Zn/SiO2 platination. EXAFS features correꢀ
sponding to PtꢀOꢀZn moieties in 1 were not detected. Addiꢀ
tionally, the EXAFS spectrum of 1 does not show higher shell
scattering paths corresponding to Pt–O–Pt and Pt–Pt moieties,
indicative of Pt monoꢀnuclearity (Figure 3b).
Figure 3. Pt L3ꢀedge spectra: (a) XANES and (b) EXAFS spectra
of preꢀcatalyst 1 (purple), preꢀcatalyst 1 treated with H2 in situ at
135 °C (2, blue), and the molecular precursor [(MeCp)PtMe3]
(red).
Table 1. EXAFS fitting summary for 1, 2, and the molecular
[(MeCp)PtMe3] reference.a
σ2
Bond
Dist. (Å)
Pt system
Path
CN
(Å2)b
PtꢀCMe
Ptꢀ PtꢀCMeCp
PtꢀCMe/O
PtꢀCMeCp
3(set)
5(set)
2.8(3)
5.0(6)
2.7(3)
4.6(6)
2.05(1)
0.0018
[(MeCp)PtMe3]
2.31(1)
2.02(1)
2.30(1)
2.02(1)
2.32(1)
0.0053
0.0018
0.0053
0.0018
0.0053
1
PtꢀCMe/O
PtꢀCMeCp
2
aS02 = 0.67, kꢀrange = 3 – 14 Åꢀ1, Rꢀrange = 1.2 – 2.2 Å, kꢀweight
= 2. bDebyeꢀWaller factor.
time (τCP = 100 ꢁs) is used, the correlations to the quaternary
carbon are absent and only singleꢀbond correlations can be
observed. When the contact time is increased to 4 ms, howevꢀ
er, a correlation between carbon A and the methyl protons of
D canbe observed. Furthermore, an additional correlation
between the methyl ligand (E) and the aromatic protons of the
MeCp ring can be observed, confirming that both ligands are
found within the same complex, in agreement with the proꢀ
posed dominant structure for 1. Note that deuterated TCE was
Solidꢀstate 13C and 195Pt NMR spectroscopy was also emꢀ
ployed to elucidate the structure of the Pt sites in 1. Due to the
low Pt loading, the application of DNP was necessary to obꢀ
tain spectra within a reasonable time.35 The DNPꢀenhanced 13
C
CPMAS spectrum of 1 (Figure 4a) shows the expected resoꢀ
nances corresponding to the methylcyclopentadienyl (δ ~ 119,
98, and 88 for the Cp (AꢀC) and 13 ppm for the MeCp (D))
and PtꢀMe (δ ~ ꢀ12 ppm (E)) ligands.36 13C{1H} HETCOR
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ꢀ = 1050 ppm, κ = 0.6). The small CSA is consistent with a
used for these measurements and thus correlations to the solꢀ
vent molecules are effectively quenched.37
pseudoꢀtetrahedral coordination environment and this resoꢀ
nance's isotropic chemical shift of ꢀ2000 ppm is exactly as
expected from the bipodal Pt complex 1, vide supra. We have
additionally acquired a 195Pt BCPꢀWCPMG spectrum of the
molecular precursor which also featured a very small CSA, in
agreement with what was observed in the surfaceꢀsupported
complex (Figure S8).
1
Unfortunately, the 13C spins from the MeCp ligand were
found to have very short T1ρ relaxation times and thus no inꢀ
formation regarding podality could be obtained from the 13C
spectra. The surface podality of the Pt(IV) sites could, howevꢀ
er, be verified via DNPꢀenhanced 195Pt SSNMR.38 195Pt chemiꢀ
cal shifts are very sensitive to local bonding environment and
span a range of 14000 ppm,39 which should enable a clear
distinction of the different coordination modes. It has been
observed that substitution of a methyl ligand for a hydroxyl
group shifts the resonance by circa 1600 ppm.40 Given that the
195Pt chemical shift of the molecular precursor [(MeCp)PtMe3]
is ꢀ5256 ppm,41 a monopodal complex can be expected to have
a chemical shift in the vicinity of ꢀ3656 ppm and a bipodal
complex at around ꢀ2056 ppm. We have thus searched for the
195Pt resonance using the BCPꢀWCPMG33 experiment starting
at ꢀ5500 ppm and increasing in frequency until a signal was
detected. No signal could be found between ꢀ5500 ppm and ꢀ
3000 ppm thus
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The DRIFTS, DRUVꢀVis, and TPRꢀH2 measurements
confirmed the presence of organic moieties in 1. Infrared abꢀ
sorptions at 3010 and 2930 cmꢀ1 were observed, attributable to
methyl and cyclopentadienyl C–H bonds, respectively (Figure
S10). The DRUVꢀVis spectrum of 1 (Figure S11) exhibits a
strong absorption at 230 nm compared to the Zn/SiO2 support.
This is likely due to ligand to metal charge transfer (LMCT)
transition of the surfaceꢀsupported (methylcyclopentadienyl)
methylplatinum(IV) sites. On the other hand, Pt nanoparticles
exhibit a broad absorption band between 350ꢀ450 nm.43 These
wellꢀdifferentiated features indicate that the electronic
structure of the Pt species in 1 and PtZn nanoparticles are
readly distinguishable, with the former having isolated and
dispersed Pt and Zn sites present. The TPRꢀH2 experiments
showed two hydrogen consumption events at 135 °C and
157 °C, the first of which occurs with observable generation of
CH4 presumably from the hydrogenolysis of Pt–Me groups
(Figure 5).
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Figure 4. (a) DNPꢀenhanced 13C CPMAS spectrum (top) and
13C{1H} HETCOR spectra (bottom) of 1. The resonances from the
complex are labeled AꢀE and identified on the structure shown; *:
TCE, †: THF, ‡ SiꢀOMe, §: SiꢀMe. Two HETCOR spectra are
shown with contact times of 100 and 4000 ꢁs; the former showing
mainly singleꢀbond correlations while the latter one also features
correlations between quaternary carbon A and the methyl protons
as well as a correlation between the methyl ligand and the Cp ring
protons (both indicated by red plus signs). (b) DNPꢀenhanced
195Pt spectra of 1 obtained using CPMAS (i) and BCPꢀWCPMG
(ii). In both cases the spectra acquired with and without microꢀ
wave irradiation are shown, as indicated on the Figure, with the
simulation overlaid in red.42
Figure 5. Temperatureꢀprogrammed reduction of 1 showing H2
consumption events occurring at 135 °C and 157 °C. Generation
of CH4 (upper plot) was observed during the H2 consumption at
135 °C.
In situ XANES experiments of 1 with H2 treatment at
135 °C occurs without an observable change in the initial Pt4+
oxidation state (XANES edge energy = 11566.4 eV), suggestꢀ
ing the likely formation of supported (MeCp)PtH/Zn/SiO2
species (2, Scheme 1). On the other hand, the hydrogen conꢀ
sumption event at 157 °C resulted in the formation of a Pt2+
species (4, XANES edge absorption energy = 11564.6 eV,
Figure S6), with an observable reduction of C–H stretching
frequencies in the DRIFTS spectrum (Figure S10), attributable
to the hydrogenolysis of the Pt–(MeCp) moiety. The two hyꢀ
drogen consumption events, give distinct supported Pt species
(Figure 5) with well differentiated catalytic behavior (vide
demonstrating that the quantity of physisorbed and/or monꢀ
opodal complexes is negligible. A strong signal was, however,
detected around ꢀ2000 ppm (Figure 4b), with a characteristic
chemical shift anisotropy (CSA) lineshape (δiso = ꢀ2000 ppm,
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trophilicity of the Pt(IV)ꢀH sites48) and steric (replacement of
infra). The formation of a supported Pt–H species (2) was
proposed via in situ DRIFTS experiments, where a broad viꢀ
bration feature at 1950ꢀ2050 cmꢀ1 was detected upon exposure
of 1 to a pure H2 feed from 50 to 150 °C (Figure 6). Note that
the observed range of Pt–H vibrational frequencies is conꢀ
sistent with reported infrared frequencies for molecular and
supported Pt–H species;44 however formation of other organoꢀ
platinum species cannot be ruled out. Similar experiments
performed using pure D2 resulted in a Pt–D formation, obꢀ
served at 1565 cmꢀ1 (Figure S13), consistent with literature
values for a Pt–D species and
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the bulkier platinumꢀbound methyl groups with a hydride)
effects. Carbonyl stretching at lower frequencies characterisꢀ
tic of the bridging CO species were not detected, consistent
with the Pt monodispersity initially observed in the EXAFS
spectrum. The spectroscopic evidence for Pt monodispersity
(Table 2) is also consistent with results of highꢀresolution
TEM imaging of 1, where Pt agglomerates were not observed
(Figure 8a).
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Figure 7. Figure 7. IRꢀCO chemisorption spectrum of 1 and 2
under various treatment conditions. The spectra for CO were colꢀ
lected after H2 treatment at 100 and 200 °C. All the spectra were
background subtracted using the spectra collected before CO exꢀ
posure at each temperature.
Figure 6. In situ DRIFTS (2200ꢀ1800 cmꢀ1 region) experiments
with 1 under pure H2 atmosphere. The DRIFTS measurements
were carried out over a range of temperatures (from 50 to 150 °C).
the DFTꢀpredicted frequency for a terminal platinum(IV) deuꢀ
teride on a Zn/SiO2 support.44aꢀc, 44e A weak vibrational feature
at 1950ꢀ2050 cmꢀ1, attributable to a possible PtꢀH species, was
also observed under a D2 atmosphere presumably due to HꢀD
exchange with surface O–H sites and generation of molecular
H–D in situ.45 Exposure of supported Pt–H species to air reꢀ
sulted in the disappearance of such feature (Figure S14). The
formation of supported Pt–H was not observed during ex situ
1H SS NMR experiments, indicating that the formation of the
supported Pt–H species may be reversible and only favored
under an atmosphere of H2.
Finally, the FTIRꢀCO chemisorption, an established
methodology to structurally characterize Pt species on surfacꢀ
es,46 was exploited to confirm the dispersity of Pt and the abꢀ
sence of clusters in 1. Exposure of 1 to CO at room temperaꢀ
ture revealed the presence of isolated, Pt4+ sites based on the
IR stretching frequencies observed at 2135 and 2145 cmꢀ1,
which disappear upon flushing with a pure He feed, attributaꢀ
ble to labile, terminally bound carbonyl ligands (Figure 7).10, 47
Treatment of 1 with H2 at 100 and 200 °C did not result in
observable formation of Pt aggregates, as evidenced by the
terminal CO absorptions at 2080 cmꢀ1, characteristic of isolatꢀ
ed Pt sites.47 Since no reduction event was observed in the in
situ XAS studies of the H2ꢀtreatment of 1 at 135 °C, the obꢀ
served nonꢀreversible CO binding sites in 2 is proposed to be
mainly due to a combination of electronic (decrease in elecꢀ
Figure 8. TEM images of the (a) asꢀprepared 1, and (b) 1 treated
with H2 at 135 °C (2).
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Table 2. Characterization Experiments and Interpretation of Zn/SiO2, (MeCp)PtMe/Zn/SiO2 (1), and (MeCp)PtH/Zn/SiO2 (2).
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System
Experiments
Observation
Interpretations
NH3ꢀTPD
DNPꢀ enhanced 17O{1H}
wPDLF
New NH3 desorption at 207 °C
Acid sites
Increased average O–H bond length of
1.034 ± 0.007 Å
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Zn/SiO2
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Isolated anchoringꢀ
sites
Zn Kꢀedge XAS
Triꢀcoordinate Zn2+
0.2 % w/w Pt
ICPꢀMS
Low metal loading
Computed thermodynamics
of the first Pt–Me protonolyꢀ
sis
Thermodynamically
favorable grafting
∆G = ꢀ12.4 kcal/mol
XANES edge absorption energy at
11566.6 eV
Pt4+
Tetrahedral Pt cenꢀ
ter stabilized by
divalent siloxy
sites, anionic
MeCp, and Me
ligands
Pt L3ꢀedge XAS
EXAFS spectrum similar to that of the
molecular [(MeCp)PtMe3] precursor
(MeCp)PtMe/Zn/SiO2 (1)
[(MeCp)PtMe]
fragment is grafted
onto Zn/SiO2
δ ~ 119, 98, and 88 for Cp, 13 ppm for
DNPꢀenhanced 13C SSNMR
MeCp, and ꢀ12 ppm for PtMe
Pseudoꢀtetrahedral
bipodal Pt complex
DNPꢀenhanced 195Pt SSNMR
DRUVꢀVis
δ ∼ −2000 ppm
Absorption at 230 nm (LMCT)
Isolated Pt atom
Stretching frequency PtꢀCO 2135 and
2145 cmꢀ1
DRIFTS CO chemisorption
Isolated Pt atom
Highꢀresolution TEM imagꢀ
ing
No observable NPs or Pt cluster
Isolated Pt atom
H2 consumption at 135 °C
H2 consumption at 158 °C
Formation of Pt4+ꢀH
Reduction to Pt2+
TPRꢀH2
XANES edge absorption energy at
11566.4 eV
Pt4+
Tetrahedral Pt cenꢀ
ter stabilized by
divalent siloxy
sites, anionic
MeCp, and H ligꢀ
ands
Pt L3ꢀedge XAS
DRIFTS H2
EXAFS spectrum similar to 1
(MeCp)PtH/Zn/SiO2 (2)
Broad stretching frequency at 1950ꢀ2050
cmꢀ1
Stretching frequency at 1565 cmꢀ1
Stretching frequency PtꢀCO at 2080 cmꢀ1
Formation of PtꢀH
DRIFTS D2
Formation of PtꢀD
Isolated Pt atom
DRIFTS CO chemisorption
Highꢀresolution TEM
imaging
No observable NPs or Pt cluster
Isolated Pt atom
Catalyst Evaluation. Catalytic hydrogenation of dienes to
butenes. The H2 consumption events observed for 1 in the
TPRꢀH2 and XANES experiments generate distinct Pt species
with potentially different reactivity. Activation of 1 with H2 at
temperatures below 100 °C, insufficient conditions to form the
active species 2, did not result in any observable 1,3ꢀbutadiene
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hydrogenation activity. On the other hand, activation at temꢀ
Page 10 of 14
1
2
3
4
5
6
7
8
peratures (>100 °C) high enough for Pt–Me hydrogenolysis
results in the catalytically active material 2 (Scheme 1) that
semiꢀhydrogenates 1,3ꢀbutadiene to a mixture of butenes, with
1ꢀbutene being the major hydrogenation product, under plugꢀ
flow reactor conditions (Figure 9). Activation of 1 to 2 over a
range of temperatures (100 to 150 °C; GHSV = 3490 hꢀ1) afꢀ
forded 14 to 44% butadiene conversion, respectively, with the
total selectivity to butenes (91ꢀ95%) largely unchanged reꢀ
gardless of the conversion level. The high monoꢀolefin selecꢀ
tivity is a strong indication of stable catalyst selectivity. Note
that under identical catalytic conditions (100 to 150 °C), 1,3ꢀ
butadiene hydrogenation with the corresponding PtZn nanoꢀ
particle catalyst (3) synthesized via calcination of 1 in air at
550 °C results in complete conversion to nꢀbutane, confirming
that the selective semiꢀhydrogenation to butenes observed with
2 is not due to nanoparticle catalysis. Moreover, 1,3ꢀbutadiene
hydrogenation with catalyst 1 activated at temperature > 150
°C (4) resulted in complete conversion along with loss of buꢀ
tene selectivity, suggesting possible formation of PtZn nanoꢀ
particles (vide infra).
Near quantitative conversion of 1,3ꢀbutadiene (86% at 150 °C;
Figure 9b) were observed with increase in catalyst loading and
slower flow rates (GHSV = 3490 hꢀ1), with the selectivity to
butenes remaining high at 89%. TEM imaging of the H2ꢀ treatꢀ
ed catalyst indicates that no sintering occurs upon reduction of
1 at 135 °C (Figure 8b), suggesting that highly dispersed Pt
sites are responsible for the observed hydrogenation activity.
Additionally, under the same reaction conditions, the nonꢀ
platinated support Zn/SiO2 is unreactive under the given conꢀ
ditions, confirming that Pt is mainly responsible for the obꢀ
served catalytic hydrogenation activity.
The catalyst preactivation temperature was observed to
affect the resulting activity and selectivity. H2ꢀactivation at
135 °C gives the more selective catalyst, while activation at
200 °C yields a nonꢀselective material. Variableꢀtemperature
DRIFTS experiments (Figure S10) revealed that preactivation
at higher temperatures (>150 °C) reductively cleaves the
MeCp–Pt group to form a Pt2+ (4, XANES edge energy =
11564.6 eV, Figure S6) species with lower chemoselectivity
for nitroꢀaromatic reduction. The removal of the MeCp group
9
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1
at 200 °C is also observed using solid state H NMR (Figure
S9). This suggests that electronic and steric contributions from
the MeCp ligand are vital to the chemoselectivity.
Nitro-aromatic reduction. The observed selective semiꢀ
hydrogenation of dienes to monoꢀolefins indicates the potenꢀ
tial utility of 2 for chemoselective hydrogenation of nitroꢀ
aromatic substrates functionalized with hydrogenationꢀ
sensitive groups. Singleꢀatom catalysts49 are, by far, the most
studied supported systems for chemoselective hydrogenation
of nitroꢀaromatics, while supported surface organometallic
catalysts, to the best of our knowledge, have never been reꢀ
ported for this chemical transformation. Both systems take
advantage of Pt site isolation and the postulate that nitro
groups are more reactive to isolated Pt sites compared to other
reducible group(s) (e.g., C=C and C=O bonds) which are more
sensitive to the size/nuclearity of the active metal. Chemoseꢀ
lective hydrogenation of 3ꢀnitrostyrene is particularly chalꢀ
lenging as C=C bonds are generally highly reactive to Pt sites.
Catalyst 2 hydrogenates 3ꢀnitrostyrene to 3ꢀaminostyrene as
the main product (Table 3, entry 1; 46% conversion, 79% seꢀ
lective) at 0.04 mol% Pt loading, 40 °C in toluene under 50 psi
H2. Under the same reaction conditions, catalyst 3 exhibits
expected nonꢀselective nanoparticleꢀlike reactivity (37% selecꢀ
tive to 3ꢀaminostyrene at 53% conversion). The observed
higher selectivity of 2 to 3ꢀaminostyrene is comparable to the
selectivities reported by Wei and coworkers for singleꢀatom
and pseudoꢀsingleꢀatom Pt sites on FeyOx support.10 Catalyst 2
exhibits higher activity and chemoselectivity, and hydrogenꢀ
ates a wider scope of functionalized nitroꢀaromatic substrates
compared to the supported PtZn nanoparticle system (3). The
wellꢀdifferentiated selectivity between catalysts 2 and 3 is a
confirmation that siteꢀisolated organoplatinum sites in 2 are
catalytically responsible for the observed reactivity. Catalyst 2
was evaluated for the reduction of a range of nitroꢀaromatics
functionalized with reactive (olefin, carbonyl, nitrile, haloꢀ
gens) groups under identical conditions: 40 °C, 50 psi H2, 24 h
(Table 3). Quantitative conversion of isomeric nitroꢀ
benzaldehydes (entries 3ꢀ4) was observed with complete tolerꢀ
ance of the aldehyde moiety. 2ꢀnitrobenzaldehyde hydrogenaꢀ
tion proceeds faster than 4ꢀnitrobenzaldehyde, presumably due
Figure 9. (a) Mildꢀcondition preꢀactivation of 1 (100 to 150 °C),
to afford catalyst 2, results in chemoselective hydrogenation of
1,3ꢀbutadiene to a mixture mainly composed of butenes (91ꢀ95%
selectivity). The formation of the secondary hydrogenation prodꢀ
uct, nꢀbutane, is minimal at different hydrogenation temperatures
and conversion levels. (b) Isothermal hydrogenation of 1,3ꢀ
butadiene at 150 °C with varying catalyst amounts (10, 20, 40,
and 80). The overall selectivity to butenes is largely unaffected by
increased conversion.
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tries 5ꢀ8). Quantitative conversions were achieved at 75 °C,
to the directing effect of the adjacent electronꢀwithdrawing
1
2
3
4
5
6
7
8
aldehyde group in the orthoꢀsubstituted substrate. Additionalꢀ
ly, the high chemoselectivity to 2ꢀaminobenzaldehyde conꢀ
firms the ability of 2 to discriminate between adjacent reduciꢀ
ble moieties, which is rarely observed with Pt nanoparticles.50
Hydrogenations with comparable rates and selectivities were
observed in the case of isomeric nitroꢀstyrenes (entries 1ꢀ2).
with complete tolerance of other hydrogenationꢀsensitive moiꢀ
eties such as aldehydes, ketones, esters, nitriles and chlorides.
In general, the selectivity levels observed are superior to other
reported supported PtZn catalysts for nitroꢀaromatic reducꢀ
tion.18c,20
Nitrobenzene is not as reactive as nitroꢀaromatics funcꢀ
tionalized with electronꢀwithdrawing groups, suggesting that
electronꢀdeficient nitroꢀaromatics are less reactive; hydrogenaꢀ
tion to aniline was only observed at higher temperatures
(75 °C, entry 9). Realꢀtime monitoring of the reduction of niꢀ
trobenzene to aniline showed no formation of partial hydroꢀ
genation (hydroxylꢀamines) and secondary products (e.g.,
dimerized products). A turnover frequency value of 809 ± 8 hꢀ1
was observed at 10% nitrobenzene conversion (Figure S15). A
threeꢀcycle recyclability test was carried out under the nitroꢀ
benzene reduction conditions described above and confirmed
that the catalyst is recyclable without any observable loss of
catalytic activity and selectivity. Filtration of the reaction mixꢀ
ture to isolate the catalyst at 91% conversion and retesting of
the liquid phase revealed that catalytically active, freely soluꢀ
ble Pt species do not leach into solution. This is consistent
with the observation that the molecular precursor
[(MeCp)PtMe3] is catalytically inactive under the given nitroꢀ
aromatic hydrogenation conditions, ultimately confirming that
supported (MeCp)PtꢀH on Zn(II)ꢀmodified SiO2 sites are reꢀ
sponsible for the observed selective catalytic reaction. Imꢀ
portantly, the stability of the supported organoplatinum(IV)
after catalysis was determined via DRIFT (Figure S17) which
confirmed the presence of the CpMe ligand. In addition, negꢀ
ligible sintering of the Pt sites on Zn/SiO2 was observed based
on TEM (Figure S18) and PXRD (Figure S19) characterizaꢀ
tion of the spent catalyst.
9
Table 3. Substrate scope study using catalyst 2: hydrogenation of
nitroꢀaromatics (0.25 M in toluene) functionalized with reducible
functionalities at 40 °C, 50 psi H2, 24 h.a
10
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Effect of loading of anchoring sites. The effect of the Zn2+
concentration was also investigated; surface saturation of SiO2
with Zn2+ (10% w/w; 75% of a theoretical Zn2+ monolayer)
gives the most active and selective catalyst at identical Pt loadꢀ
ings. Lower Zn2+ loadings resulted in observable Pt aggregaꢀ
tion in the TEM image, forming crystalline ensembles that are
less active and selective to 3ꢀaminostyrene (Figure S15). The
agglomeration of Pt on lowꢀZn2+ supports presumably arises
from the presence of bare SiO2 surface sites where Pt migraꢀ
tion and sintering occur more easily. Surface saturation of
SiO2 with Zn2+ sites confirms our hypothesis on the positive
effect of Zn2+ anchoring sites on Pt stability. In addition, the
deposition methods and dispersion of Zn2+ sites on SiO2 were
observed to affect the dispersion of Pt sites and, in turn, the
catalyst chemoselectivity. The Pt catalysts deposited on ALDꢀ
synthesized Zn(10%)/SiO2 with monodispersed Zn2+ sites,
showed superior performance compared to the corresponding
Zn(10%)/SiO2 support prepared by SEA. The presence of
monomeric and oligomeric Zn sites on the Zn/SiO2ꢀSEA was
confirmed by DRUVꢀVis spectroscopy (Figure S12).
aReaction conversions are based on measured GC concentrations.
bThe reaction was carried out at 75 °C. c4ꢀethylaniline was formed
Conclusions
The stabilization of isolated platinum sites on weakly inꢀ
teracting, highꢀsurfaceꢀarea oxides supports, such as silica, has
been a major challenge in the development of chemoselective
surfaceꢀsupported Pt catalysts. Due to the weak Pt–support
interaction, most synthetic protocols for Pt deposition on SiO2
d
as the main product. Dimerized anilines were detected as minor
products.
On the other hand, modest conversions were observed for niꢀ
troꢀaromatics with polar, hydrogenationꢀsensitive groups (enꢀ
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Journal of the American Chemical Society
Page 12 of 14
AC02ꢀ06CH11357 (Argonne National Laboratory) and DEꢀ
result in a distribution of sites, compromising catalytic selecꢀ
tivity. This work successfully demonstrated that roomꢀ
temperature grafting of isolated organoplatinum(IV) catalyst
can be achieved using a modified silica support, equipped with
Lewis acid anchoring sites such as Zn2+. The use of ALD was
critical in enforcing uniform distribution of cationic zinc anꢀ
choring sites; traditional Zn deposition techniques, such as
SEA and hydrothermal protocols, are less effective in dispersꢀ
ing zinc due to agglomeration, particularly at surface saturaꢀ
tion. The resulting surfaceꢀsupported organoplatinum(IV)
sites were fully characterized using a combination of ex situ
and in situ spectroscopic techniques, including XAS, DRUVꢀ
Vis, DRIFTS, DNPꢀenhanced SSNMR (1H, 13C, 17O, 195Pt),
TPRꢀH2 and TEM. The cationic Zn anchoring sites stabilize
highꢀvalent oxidation state metals (i.e., Pt4+), promote in situ
formation of a probable metalꢀhydride, and prevent sintering
and catalyst deactivation. Supported organoplatinum species
are chemoselective catalysts for the semiꢀhydrogenation of
1,3ꢀbutadiene to a mixture of butenes and reduction of funcꢀ
tionalized nitroꢀaromatic with excellent tolerance of sensitive
functional groups, such as olefins, carbonyls, nitriles, and halꢀ
ogens.
AC02ꢀ07CH11358 (Ames Laboratory). The calculations were
performed using the computational resources provided by the
Laboratory Computing Resource Center (LCRC) at Argonne and
National Energy Research Scientific Computing (NERSC) Center.
Use of the Advanced Photon Source is supported by the U.S. Deꢀ
partment of Energy, Office of Science, and Office of the Basic
Energy Sciences, under Contract DEꢀACꢀ02ꢀ06CH11357.
MRCAT operations are supported by the Department of Energy
and the MRCAT member institutions. Use of the TEM at the Cenꢀ
ter for Nanoscale Materials at Argonne National Laboratory is
supported by the U.S. Department of Energy, Office of Science,
Office of Basic Energy Sciences, under Contract DEꢀAC02ꢀ
06CH11357. Partial support for F.P. was through a Spedding
Fellowship funded by the Laboratory Directed Research and Deꢀ
velopment (LDRD) program at the Ames Laboratory. F. P.
thanks NSERC and the Government of Canada for a Banting
Postdoctoral Fellowship. We thank Dr. A. P. Sattelberger for
helpful discussion.
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References
1. (a) Monguchi, Y.; Ichikawa, T.; Sajiki, H. Chem. Pharm. Bull.
2017, 65, 2ꢀ9; (b) Virtanen, P.; Salminen, E.; MakiꢀArvela, P.;
Mikkola, J.ꢀP. In Selective hydrogenation for fine chemical
synthesis, WileyꢀVCH Verlag GmbH & Co. KGaA: 2014; pp 251ꢀ
262; (c) Thomas, S. P.; Greenhalgh, M. D. In Heterogeneous
hydrogenation of C=C and C≡C bonds, Elsevier B.V.: 2014; pp
564ꢀ604; (d) Blaser, H.ꢀU.; Steiner, H.; Studer, M. ChemCatChem
2009, 1, 210ꢀ221.
2. Suchy, M.; Winternitz, P.; Zeller, M. Catal. Today 1997, 37,
121ꢀ136.
3. Yang, X.ꢀJ.; Chen, B.; Zheng, L.ꢀQ.; Wu, L.ꢀZ.; Tung, C.ꢀH.
Green Chem. 2014, 16, 1082ꢀ1086.
4. (a) Imamura, K.; Hashimoto, K.; Kominami, H. Chem.
Commun. 2012, 48, 4356ꢀ4358; (b) Corma, A.; Serna, P. Science
2006, 313, 332ꢀ334; (c) Blaser, H.ꢀU.; Studer, M. Appl. Catal. A
1999, 189, 191ꢀ204.
5. Herkes, F. E., Catalysis of organic reactions. CRC Press: 1998;
Vol. 75.
In summary, a general strategy for the modification of
high surface area oxide supports, such as silica, with cationic
Zn anchoring sites via ALD afforded novel catalyst support
with tunable acidic and electronic properties. This catalyst
design strategy provides a potentially general design principle
for the rational development of new classes of monoꢀ and mulꢀ
timetallic selective catalysts. Further studies are ongoing to
explore and demonstrate the generality of this catalyst design
strategy and synthetic approach. In particular, Lewis acids
and/or redoxꢀactive cationic anchoring sites, such as Al3+, Ga3+
and Ce4+, will be employed in the development of a series of
surfaceꢀsupported organoplatinum(IV) catalysts, which will be
fully characterized, and evaluated for the chemoselective hyꢀ
drogenation of dienes and nitroꢀaromatics (Table S2).
6. Serna, P.; Concepción, P.; Corma, A. J. Catal. 2009, 265, 19ꢀ
25.
7. Corma, A.; Serna, P.; Concepción, P.; Calvino, J. J. J. Am.
Chem. Soc 2008, 130, 8748ꢀ8753.
ASSOCIATED CONTENT
Supporting Information. This material is available free of
charge via the Internet at http://pubs.acs.org.
8. Pang, H.; Gallou, F.; Sohn, H.; CamachoꢀBunquin, J.; Delferro,
M.; Lipshutz, B. H. Green Chem. 2018, 20, 130ꢀ135.
9. Serna, P.; Corma, A. ACS Catal. 2015, 5, 7114ꢀ7121.
10. Wei, H.; Liu, X.; Wang, A.; Zhang, L.; Qiao, B.; Yang, X.;
Huang, Y.; Miao, S.; Liu, J.; Zhang, T. Nat. Commun. 2014, 5,
5634.
11. (a) Coperet, C.; Estes, D. P.; Larmier, K.; Searles, K. Chem.
Rev. 2016, 116, 8463ꢀ8505; (b) Copéret, C.; ComasꢀVives, A.;
Conley, M. P.; Estes, D. P.; Fedorov, A.; Mougel, V.; Nagae, H.;
NúñezꢀZarur, F.; Zhizhko, P. A. Chem. Rev. 2016, 116, 323ꢀ421;
(c) Conley, M. P.; Coperet, C. Top. Catal. 2014, 57, 843ꢀ851; (d)
Coperet, C. Chem. Rev. 2010, 110, 656ꢀ680; (e) Copéret, C.;
Chabanas, M.; Petroff SaintꢀArroman, R.; Basset, J.ꢀM. Angew.
Chem. Int. Ed. 2003, 42, 156ꢀ181.
12. (a) Pelletier, J. D. A.; Basset, J.ꢀM. Acc. Chem. Res. 2016, 49,
664ꢀ677; (b) Basset, J.ꢀM.; Coperet, C.; Soulivong, D.; Taoufik,
M.; Thivolle, C. J. Acc. Chem. Res. 2010, 43, 323ꢀ334; (c) Basset,
J. M.; Ugo, R. In On the origins and development of "surface
organometallic chemistry", WileyꢀVCH Verlag GmbH & Co.
KGaA: 2009; pp 1ꢀ21; (d) Lefebvre, F.; Basset, J. M. J. Mol.
Catal. A: Chem. 1999, 146, 3ꢀ12.
Details of the synthesis of Zn/SiO2 support, NH3ꢀTPD
plot, additional DFT calculations and coordinates, addiꢀ
tional XAS spectra, additional DRIFTS data, DRUVꢀVis
data, additional DNP data, conversion vs time plot of niꢀ
trobenzene hydrogenation, additional TEM images,
PXRD and DRIFT spectra of the spent catalyst, scoping
of platinum anchoring sites/promoters on SiO2.
AUTHOR INFORMATION
Corresponding Authors
M.
Delferro
(delferro@anl.gov),
J.
C.
Stair
(pstair@northwestern.edu),
CamachoꢀBunquin
(jeffrey.c.bunquin@exxonmobil.com).
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENT
13. (a) Stalzer, M. M.; Delferro, M.; Marks, T. J. Catal. Lett.
2015, 145, 3ꢀ14; (b) Wegener, S. L.; Marks, T. J.; Stair, P. C. Acc.
This work was supported by the U.S. Department of Energy
(DOE), Office of Basic Energy Sciences, Division of Chemical
Sciences, Geosciences, and Biosciences, under Contract DEꢀ
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Page 13 of 14
Journal of the American Chemical Society
Chem. Res. 2012, 45, 206ꢀ214; (c) Marks, T. J. Acc. Chem. Res.
1992, 25, 57ꢀ65.
17. (a) Santori, G. F.; Casella, M. L.; Ferretti, O. A. J. Mol. Catal.
A Chem. 2002, 186, 223ꢀ239; (b) Hermans, S.; Raja, R.; Thomas,
J. M.; Johnson, B. F.; Sankar, G.; Gleeson, D. Angew. Chem., Int.
Ed. 2001, 40, 1211ꢀ1215; (c) Santori, G. F.; Casella, M. L.; Siri,
G. J.; Adúriz, H. R.; Ferretti, O. A. Appl. Catal. A 2000, 197, 141ꢀ
149; (d) Gallezot, á.; Richard, D. Catal. Rev. 1998, 40, 81ꢀ126; (e)
Claus, P. Top. Catal. 1998, 5, 51ꢀ62; (f) Candy, J.ꢀP.; Didillon,
B.; Smith, E. L.; Shay, T. B.; Basset, J.ꢀM. J. Mol. Catal. 1994,
86, 179ꢀ204; (g) Didillon, B.; Candy, J.; El Mansour, A.;
Houtmann, C.; Basset, J.ꢀM. J. Mol. Catal. 1992, 74, 43ꢀ49; (h)
Lecuyer, C.; Quignard, F.; Choplin, A.; Olivier, D.; Basset, J. M.
Angew. Chem., Int. Ed. 1991, 30, 1660ꢀ1661; (i) Ferretti, O.;
Bournonville, J.; Mabilon, G.; Martino, G.; Candy, J.; Basset, J.ꢀ
M. J. Mol. Catal. 1991, 67, 283ꢀ294; (j) Agnelli, M.; Louessard,
P.; El Mansour, A.; Candy, J.; Bournonville, J.; Basset, J. Catal.
Today 1989, 6, 63ꢀ72; (k) Ugo, R. Cat. Rev. ꢁ Sci. Eng. 1975, 11,
225ꢀ297.
18. (a) Cybulskis, V. J.; Bukowski, B. C.; Tseng, H.ꢀT.;
Gallagher, J. R.; Wu, Z.; Wegener, E.; Kropf, A. J.; Ravel, B.;
Ribeiro, F. H.; Greeley, J.; Miller, J. T. ACS Catal. 2017, 7, 4173ꢀ
4181; (b) Qi, Z.; Xiao, C.; Liu, C.; Goh, T. W.; Zhou, L.; Maligalꢀ
Ganesh, R.; Pei, Y.; Li, X.; Curtiss, L. A.; Huang, W. J. Am.
Chem. Soc. 2017, 139, 4762ꢀ4768; (c) Iihama, S.; Furukawa, S.;
Komatsu, T. ACS Catal. 2016, 6, 742ꢀ746; (d) Zhu, J.; Zheng, X.;
Wang, J.; Wu, Z.; Han, L.; Lin, R.; Xin, H. L.; Wang, D. J. Mater.
Chem. A Energy Sustain. 2015, 3, 22129ꢀ22135; (e) Sode, A.;
Musgrove, A.; Bizzotto, D. J. Phys. Chem. C 2010, 114, 546ꢀ553;
(f) Miura, A.; Wang, H.; Leonard, B. M.; Abruna, H. D.; Di
Salvo, F. J. Chem. Mater. 2009, 21, 2661ꢀ2667.
1
2
3
4
5
6
7
8
14. (a) Sohn, H.; CamachoꢀBunquin, J.; Langeslay, R. R.;
Ignacioꢀde Leon, P. A.; Niklas, J.; Poluektov, O. G.; Liu, C.;
Connell, J. G.; Yang, D.; Kropf, J.; Kim, H.; Stair, P. C.;
Ferrandon, M.; Delferro, M. Chem. Commun. 2017, 53, 7325ꢀ
7328; (b) Lohr, T. L.; Mouat, A.; Schweitzer, N. M.; Stair, P. C.;
Delferro, M.; Marks, T. Energ. Environ. Sci. 2017, 10, 1558ꢁ
1562; (c) CamachoꢀBunquin, J.; Ferrandon, M.; Das, U.; Dogan,
F.; Liu, C.; Larsen, C.; PlateroꢀPrats, A. E.; Curtiss, L. A.; Hock,
A. S.; Miller, J. T.; Nguyen, S. T.; Marshall, C. L.; Delferro, M.;
Stair, P. C. ACS Catal. 2017, 7, 689ꢀ694; (d) Stalzer, M. M.;
Nicholas, C. P.; Bhattacharyya, A.; Motta, A.; Delferro, M.;
Marks, T. J. Angew. Chem., Int. Ed. 2016, 55, 5263ꢀ5267; (e)
Mouat, A. R.; Lohr, T. L.; Wegener, E. C.; Miller, J. T.; Delferro,
M.; Stair, P. C.; Marks, T. J. ACS Catal. 2016, 6, 6762ꢀ6769; (f)
Liu, S.; Tan, J. M.; Gulec, A.; Schweitzer, N. M.; Delferro, M.;
Marks, L. D.; Stair, P. C.; Marks, T. J. ACS Catal. 2016, 6, 8380ꢀ
8388; (g) Gu, W.; Stalzer, M. M.; Nicholas, C. P.; Bhattacharyya,
A.; Motta, A.; Gallagher, J. R.; Zhang, G.; Miller, J. T.;
Kobayashi, T.; Pruski, M.; Delferro, M.; Marks, T. J. J. Am.
Chem. Soc. 2015, 137, 6770ꢀ6780; (h) Williams, L. A.; Guo, N.;
Motta, A.; Delferro, M.; Fragala, I. L.; Miller, J. T.; Marks, T. J.
Proc. Natl. Acad. Sci. U. S. A. 2013, 110, 413ꢀ418.
15. (a) Brown, C.; Lita, A.; Tao, Y.; Peek, N.; Crosswhite, M.;
Mileham, M.; Krzystek, J.; Achey, R.; Fu, R.; Bindra, J. K.;
Polinski, M.; Wang, Y.; van de Burgt, L. J.; Jeffcoat, D.; Profeta,
S.; Stiegman, A. E.; Scott, S. L. ACS Catal. 2017, 7, 7442ꢀ7455;
(b) Gallo, A.; Fong, A.; Szeto, K. C.; Rieb, J.; Delevoye, L.;
Gauvin, R. M.; Taoufik, M.; Peters, B.; Scott, S. L. J. Am. Chem.
Soc. 2016, 138, 12935ꢀ12947; (c) Fong, A.; Peters, B.; Scott, S. L.
ACS Catal. 2016, 6, 6073ꢀ6085; (d) Szeto, K. C.; Gallo, A.;
HernandezꢀMorejudo, S.; Olsbye, U.; De Mallmann, A.;
Lefebvre, F.; Gauvin, R. M.; Delevoye, L.; Scott, S. L.; Taoufik,
M. J. Phys. Chem. C 2015, 119, 26611ꢀ26619; (e) Goldsmith, B.
R.; Hwang, T.; Seritan, S.; Peters, B.; Scott, S. L. J. Am. Chem.
Soc. 2015, 137, 9604ꢀ9616; (f) Fleischman, S. D.; Scott, S. L. J.
Am. Chem. Soc. 2011, 133, 4847ꢀ4855; (g) Hisamoto, M.; Nelson,
R. C.; Lee, M.ꢀY.; Eckert, J.; Scott, S. L. J. Phys. Chem. C 2009,
113, 8794ꢀ8805; (h) Moses, A. W.; Raab, C.; Nelson, R. C.;
Leifeste, H. D.; Ramsahye, N. A.; Chattopadhyay, S.; Eckert, J.;
Chmelka, B. F.; Scott, S. L. J. Am. Chem. Soc. 2007, 129, 8912ꢀ
8920; (i) Moses, A. W.; Ramsahye, N. A.; Raab, C.; Leifeste, H.
D.; Chattopadhyay, S.; Chmelka, B. F.; Eckert, J.; Scott, S. L.
Organometallics 2006, 25, 2157ꢀ2165; (j) Richmond, M. K.;
Scott, S. L.; Yap, G. P. A.; Alper, H. Organometallics 2002, 21,
3395ꢀ3400; (k) Beaudoin, M. C.; Womiloju, O.; Fu, A.; Ajjou, J.
A. N.; Rice, G. L.; Scott, S. L. J. Mol. Catal. A: Chem. 2002, 190,
159ꢀ169; (l) Richmond, M. K.; Scott, S. L.; Alper, H. J. Am.
Chem. Soc. 2001, 123, 10521ꢀ10525; (m) Bouh, A. O.; Rice, G.
L.; Scott, S. L. J. Am. Chem. Soc. 1999, 121, 7201ꢀ7210; (n)
Ajjou, J. A. N.; Scott, S. L.; Paquet, V. J. Am. Chem. Soc. 1998,
120, 415ꢀ416; (o) Ajjou, J. A. N.; Scott, S. L. Organometallics
1997, 16, 86ꢀ92.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
19. CamachoꢀBunquin, J.; Shou, H.; Aich, P.; Beaulieu, D. R.;
Klotzsch, H.; Bachman, S.; Marshall, C. L.; Hock, A.; Stair, P.
Rev. Sci. Instrum. 2015, 86, 084103.
20. CamachoꢀBunquin, J.; Aich, P.; Ferrandon, M.; Das, U.;
Dogan, F.; Curtiss, L. A.; Miller, J. T.; Marshall, C. L.; Hock, A.
S.; Stair, P. C. J. Catal. 2017, 345, 170ꢀ182.
21. (a) Becke, A. D. J. Phys. Chem. 1993, 98, 5648ꢀ5652; (b) Lee,
C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785ꢀ789.
22. Schafer, A.; Huber, C.; Ahlrichs, R. J. Phys. Chem. 1994, 100,
5829ꢀ5835.
23. Gaussian 09, R. E., Frisch, M. J.; Trucks, G. W.; Schlegel, H.
B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.;
Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.;
Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.;
Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.;
Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.;
Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta,
J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin,
K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.;
Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.;
Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox,
J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.;
Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.;
Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.;
Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, Ö.;
Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian,
Inc., Wallingford CT, 2009.
24. Das, U.; Zhang, G.; Hu, B.; Hock, A. S.; Redfern, P. C.;
Miller, J. T.; Curtiss, L. A. ACS Catal. 2015, 5, 7177ꢀ7185.
25. Zagdoun, A.; Casano, G.; Ouari, O.; Schwarzwälder, M.;
Rossini, A. J.; Aussenac, F.; Yulikov, M.; Jeschke, G.; Copéret,
C.; Lesage, A.; Tordo, P.; Emsley, L. J. Am. Chem. Soc 2013,
135, 12790ꢀ12797.
26. (a) Gansmüller, A.; Simorre, J.ꢀP.; Hediger, S. J. Magn.
Reson. 2013, 234, 154ꢀ164; (b) Dvinskikh, S. V.; Zimmermann,
H.; Maliniak, A.; Sandström, D. J. Magn. Reson. 2004, 168, 194ꢀ
201.
16. (a) Boukebbous, K.; Merle, N.; Larabi, C.; Garron, A.;
Darwich, W.; Laifa, E. A.; Szeto, K.; De Mallmann, A.; Taoufik,
M. New J. Chem. 2017, 41, 427ꢀ431; (b) Fedorov, A.; Liu, H.ꢀJ.;
Lo, H.ꢀK.; Copéret, C. J. Am. Chem. Soc 2016, 138, 16502ꢀ
16507; (c) Uberman, P. M.; Costa, N. J. S.; Philippot, K.; C.
Carmona, R.; Dos Santos, A. A.; Rossi, L. M. Green Chem. 2014,
16, 4566ꢀ4574; (d) Serna, P.; Gates, B. C. Acc. Chem. Res. 2014,
47, 2612ꢀ2620; (e) Merlo, A. B.; Vetere, V.; Casella, M. L. Curr.
Catal. 2014, 3, 244ꢀ253; (f) Thomas, J. M.; Raja, R. J.
Organomet. Chem. 2004, 689, 4110ꢀ4124; (g) Didillon, B.; Le
Peltier, F.; Candy, J. P.; Boitiaux, J. P.; Basset, J. M. Stud. Surf.
Sci. Catal. 1992, 73, 23ꢀ30.
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Journal of the American Chemical Society
Page 14 of 14
27. Larsen, F. H.; Jakobsen, H. J.; Ellis, P. D.; Nielsen, N. C. J.
42. Zagdoun, A.; Casano, G.; Ouari, O.; Schwarzwälder, M.;
Magn. Reson. 1998, 131, 144ꢀ147.
28. Perras, F. A.; Wang, Z.; Naik, P.; Slowing, I. I.; Pruski, M.
Angew. Chem., Int. Ed. 2017, 56, 9165ꢀ9169.
29.Perras, F. A.; Kobayashi, T.; Pruski, M. J. Am. Chem. Soc.
2015, 137, 8336ꢀ8339.
30. Bielecki, A.; Kolbert, A. C.; Levitt, M. H. Chem. Phys. Lett.
1989, 155, 341ꢀ346.
Rossini, A. J.; Aussenac, F.; Yulikov, M.; Jeschke, G.; Copéret,
C.; Lesage, A. J. Am. Chem. Soc 2013, 135, 12790ꢀ12797.
43. (a) Zhang, N.; Han, C.; Xu, Y.ꢀJ.; Foley Iv, J. J.; Zhang, D.;
Codrington, J.; Gray, S. K.; Sun, Y. Nat. Photonics 2016, 10, 473;
(b) Czaplinska, J.; Decyk, P.; Ziolek, M. Appl. Catal. A: Gen.
2015, 504, 361ꢀ372; (c) Sortino, S.; Petralia, S.; Conoci, S.; Di
Bella, S. J. Mater. Chem. 2004, 14, 811ꢀ813.
1
2
3
4
5
6
7
8
9
31. Harris, K. J.; Lupulescu, A.; Lucier, B. E. G.; Frydman, L.;
Schurko, R. W. J. Magn. Reson. 2012, 224, 38ꢀ47.
32. Kupce, E.; Freeman, R. J. Magn. Reson. 1995, 115, 273ꢀ276.
33. O’Dell, L. A.; Schurko, R. W. Chem. Phys. Lett. 2008, 464,
97ꢀ102.
34. Schweitzer, N. M.; Hu, B.; Das, U.; Kim, H.; Greeley, J.;
Curtiss, L. A.; Stair, P. C.; Miller, J. T.; Hock, A. S. ACS Catal.
2014, 4, 1091ꢀ1098.
35. (a) Kobayashi, T.; Perras, F. A.; Slowing, I. I.; Sadow, A. D.;
Pruski, M. ACS Catal. 2015, 5, 7055; (b) Rossini, A. J.; Zagdoun,
A.; Lelli, M.; Lesage, A.; Copéret, C.; Emsley, L. Acc. Chem. Res.
2013, 46, 1942ꢀ1951; (c) Lesage, A.; Lelli, M.; Gajan, D.;
Caporini, M. A.; Vitzthum, V.; Miéville, P.; Alauzun, J.; Roussey,
A.; Thieuleux, C.; Mehdi, A. J. Am. Chem. Soc 2010, 132, 15459ꢀ
15461; (d) Maly, T.; Debelouchina, G. T.; Bajaj, V. S.; Hu, K.ꢀN.;
Joo, C.ꢀG.; Mak–Jurkauskas, M. L.; Sirigiri, J. R.; van der Wel, P.
C.; Herzfeld, J.; Temkin, R. J. J. Phys. Chem. 2008, 128, 02B611.
36. Xue, Z.; Strouse, M. J.; Shuh, D. K.; Knobler, C. B.; Kaesz,
H. D.; Hicks, R. F.; Williams, R. S. J. Am. Chem. So 1989, 111,
8779ꢀ8784.
37. Kobayashi, T.; Perras, F. A.; Chaudhary, U.; Slowing, I. I.;
Huang, W.; Sadow, A. D.; Pruski, M. Solid State Nucl. Magn.
Reson. 2017, 87, 38ꢀ44.
38. Kobayashi, T.; Perras, F. A.; Goh, T. W.; Metz, T. L.; Huang,
W.; Pruski, M. J. Phys. Chem. Lett. 2016, 7, 2322ꢀ2327.
39. Still, B. M.; Kumar, P. G. A.; AldrichꢀWright, J. R.; Price, W.
S. Chem. Soc. Rev. 2007, 36, 665ꢀ686.
40. Pregosin, P. S., Platinum NMR Spectroscopy. In Annual
Reports on NMR Spectroscopy, Webb, G. A., Ed. Academic
Press: 1986, 17, 285ꢀ349.
41. Boardman, L. D.; Newmark, R. A. Magn. Reson. Chem. 1992,
30, 481ꢀ489.
44. (a) Andrews, L.; Wang, X.; Manceron, L. J. Phys. Chem.
2001, 114, 1559ꢀ1566; (b) Prokopchuk, E. M.; Jenkins, H. A.;
Puddephatt, R. J. Organometallics 1999, 18, 2861ꢀ2866; (c)
Yoshida, T.; Yamagata, T.; Tulip, T.; Ibers, J. A.; Otsuka, S. J.
Am. Chem. Soc 1978, 100, 2063ꢀ2073; (d) Gavrllova, I.;
Gelhman, M. Russ. J. Inorg. Chem. 1971, 16, 596; (e) Clark, H.;
Tsang, W. J. Am. Chem. Soc 1967, 89, 529ꢀ533.
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
45. Martin, D.; Duprez, D. J. Phys. Chem. B 1997, 101, 4428ꢀ
4436.
46. (a) Liu, S.; Tan, J. M.; Gulec, A.; Crosby, L. A.; Drake, T. L.;
Schweitzer, N. M.; Delferro, M.; Marks, L. D.; Marks, T. J.; Stair,
P. C. Organometallics 2017, 36, 818ꢀ828; (b) Ding, K.; Gulec, A.;
Johnson, A. M.; Schweitzer, N. M.; Stucky, G. D.; Marks, L. D.;
Stair, P. C. Science 2015, 350, 189ꢀ192; (c) Kistler, J. D.;
Chotigkrai, N.; Xu, P.; Enderle, B.; Praserthdam, P.; Chen, C.ꢀY.;
Browning, N. D.; Gates, B. C. Angew. Chem., Int Ed. 2014, 53,
8904ꢀ8907; (d) MosesꢀDeBusk, M.; Yoon, M.; Allard, L. F.;
Mullins, D. R.; Wu, Z.; Yang, X.; Veith, G.; Stocks, G. M.;
Narula, C. K. J. Am. Chem. Soc 2013, 135, 12634ꢀ12645; (e)
Akdogan, Y.; Vogt, C.; Bauer, M.; Bertagnolli, H.; Giurgiu, L.;
Roduner, E. Phys. Chem. Chem. Phys. 2008, 10, 2952ꢀ2963; (f)
Panagiotopoulou, P.; Christodoulakis, A.; Kondarides, D. I.;
Boghosian, S. J. Catal. 2006, 240, 114ꢀ125.
47. Qiao, B.; Wang, A.; Yang, X.; Allard, L. F.; Jiang, Z.; Cui, Y.;
Liu, J.; Li, J.; Zhang, T. Nat. Chem. 2011, 3, 634ꢀ641.
48. Forniés, J.; GómezꢀSaso, M. A.; Martín, A.; Martínez, F.;
Menjón, B.; Navarrete, J. Organometallics 1997, 16, 6024ꢀ6027.
49. Liu, J. ACS Catal. 2017, 7, 34ꢀ59.
50. Pt is generally not very active for aldehyde and ketone
hydrogenation.
Table of Content Graphic
NO2
+ H2
+ H2
CH3
X
H
Pt
Zn
O
Si
O
X = vinyl, aldehyde, ketone,
O
O
O
ester, nitrile, halide
O
O
Si
Si
O
Si
O
O
O
NH2
O
O
O
X
Supported OrganoPlatinum(IV)-Hydride Catalyst
ACS Paragon Plus Environment