Photon Factory Activity Report 2004 #22 Part B (2005)
Chemistry

10B/2004G082

XAFS Characterization of Oxide-Surface Supported Pd Complexesfor Alkene Hydroamination
MizukiTADA1, Michio SHIMAMOTO1, Takehiko SASAKI1, and Yasuhiro IWASAWA*1
1
Department of Chemistry, Graduate School of Science, The University of Tokyo
Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan

ClClLPdL

L+OH

Pd

LO

MeCH4

SiO2, Al2O3, TiO2

L: P(O-iPr)3
PMe2Ph
Me2N

Ph2P
NMe2
Ph2PFeH2NNH

Scheme 1 Preparation of the oxide-supported Pdcomplexes for alkene hydroamination.
Results and Discussion
The CH3 groups selectively reacted with surface OH
groups to evolve CH4. The N and P ligands of theprecursors did not dissociate into the solution during theattaching reaction. The chlorine ligands remained on Pd
as estimated by the intensity ratios of XPS Cl2p and Pd3dpeaks for both Pd-P and Pd-N complexes.
The curve-fitting analysis for the Pd K-edge EXAFS
Fourier-transformed spectra of the Pd-P complexes(A)

203k χ(k)4-2-4-646810

1214

56-1k/10 nm
10(B)863Experimental
Some new Pd monomers with Pd-P or Pd-N bonds
were supported on SiO2, Al2O3, and TiO2 as shown in
Scheme 1. The structures of the supported Pd complexes
were characterized by XRF, XPS, GC, and EXAFS. Pd
K-edge EXAFS spectra were measured at BL-10B station
in a transmission mode at 15 K. Background subtraction
was conducted by the AUTOBK program, and Fourier-1transformed spectra (k=30-140 nm , R=0.12-0.24 nm)
were fitted in R space by FEFFIT program. The catalytichydroamination of 3-amino propanol vinyl ether was
carried out in toluene at 343 K under a nitrogen
atmosphere monitored by GC and GC-MASS.

6FT [k χ(k)]Introduction
Amine derivatives, which are valuable and importantchemicals, have been produced via several synthetic
processes. The direct synthesis of a new C-N bond by theaddition of an amine to an unsaturated C-C bond,hydroamination, is of great significance. However, thisreaction is generally slightly exothermic and entropicallynegative, and the hydroamination of alkenes is highly
difficult compared to that of alkynes because of the lower
electron density of C=C bonds than C-C bonds. We havesucceeded in the preparation of oxide-surface supported
Pd complexes for the catalytic intrahydroamination of 3amino propanol vinyl ether to produce the corresponding
cyclic amine. This is the first heterogeneous catalyst foralkene hydroamination [1].

420-2-4-6
0

1

2

34-1

R/10 nm

Figure 1 A Pd K-edge EXAFS oscillation (A) and its
Fourier-transformed spectra (B) for the supported PdP(O-iPr)3 complex on a SiO2 surface.
revealed that the existence of a Pd-O bond at 0.212 nm(CN=0.8) and Pd-P(Cl) bonds at 0.235 nm (CN=3.1) (Fig.
1). The bond distances in the Pd-N complexes supported
on SiO2 (Pd-N(O): 0.213 nm and Pd-Cl: 0.235 nm) weresimilar to those in the supported Pd-P complexes. The
results demonstrate a similar bonding feature in thecoordination sphere around Pd in the catalysts derived
from both precursors.
The supported Pd catalysts exhibited high catalytic
activity for the alkene hydroamination. No changes in thecoordination numbers and bond distances around the Pd
center after the catalytic reaction was observed by
EXAFS curve-fitting, suggesting that the supported Pdcomplexes are not only active but also durable for thecatalytic hydroamination.
References[1] M. Tada, M. Shimamoto, T. Sasaki, and Y. Iwasawa,Chem. Commun., 2562 (2004).
* iwasawa@chem.s.u-tokyo.ac.jp

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