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BELYKH et al.
broadening is assumed to occur due to the triethylalu- introduction of triphenylphosphine favors the forma-
minium coordination by Pd or AlEt2(Acac) contained tion of a highly dispersed system.
on the surface of the Pd(0) particles. The AlEt2(Acac)
concentration decreasing with time and the increasing
broad signals at 1.4 and 0.4 ppm make the second
assumption preferable.
REFERENCES
1. Shmidt, F.K., Kataliz kompleksami metallov pervogo
perekhodnogo ryada reaktsii gidrirovaniya i dimerizatsii
The 31P NMR spectrum of the reaction system
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Transition Row Metal Complexes), Irkutsk: IGU, 1986.
Pd(Acac)2PPh3–nAlEt3 recorded at different reagent
ratios (n = 2, 3.4, 6) exhibits a broad signal at 22 ppm
characteristic of PPh3 coordinated by the Pd atoms in
the lowest oxidation states.
2. Schmidt, F.K., Ratovskii, G.V., Dmitrieva, T.V., et al.,
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A black precipitate isolated from the Pd(Acac)2PPh3–
3.4AlEt3 system is the X-ray amorphous compound
with the ratio Pd : Al : P = 1 : 0.4 : 0.6. The IR spectrum
of the sample contains the absorption bands due to
AlEt2(Acac) (1587, 1525, 1284 cm–1), and due to off-
plane deformation vibrations of the C–H and C–C bonds
in monosubstituted benzene ring (706, 676 cm–1).
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The electron-microscope picture of the Pd(Acac)2PPh3–
3.4AlEt3 system shows highly contrast particles with the
predominant diameter of 2.5 nm (Fig. 4).
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The data obtained make it possible to suggest that
the reaction of Pd(Acac)2PPh3 with triethylaluminium
(Al : Pd = 3.4) in an inert atmosphere gives Pd(0) nano-
particles, stabilized by both AlEt2(Acac) and triphen-
ylphosphine.
12. Metody kolichestvennogo organicheskogo elementnogo
mikroanaliza (Methods of Quantitative Organic Elemen-
tal Microanalysis), Gel’man, N.E., Ed., Moscow:
Khimiya, 1987, p. 177.
The study of the reaction of Pd acetylacetonate com-
plexes with triethylaluminium showed that the interac-
tion between the initial components included the
exchange of the Acac– ligands for Et; the subsequent
β-hydride shift results in the reduction of Pd(II) to
Pd(0) and the formation of the Pd nanoparticles. The
ligand surrounding and the size of the Pd nanoparticles
are determined by theAl : Pd ratio. Triphenylphosphine
stabilizes the Pd complexes and thus prevents coordina-
tion of AlEt3 and hampers its further destruction. The
13. Pasynkiewich, S. and Dowbor, K., J. Organomet. Chem.,
1974, vol. 78, p. 49.
14. Pomogailo, A.D., Rozenberg, A.F., and Uflyand, E.I.,
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Moscow: Nauka, 1987.
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