Russian Journal of General Chemistry, Vol. 73, No. 8, 2003, p. 1319. Translated from Zhurnal Obshchei Khimii, Vol. 73, No. 8, 2003, pp. 1394 1395.
Original Russian Text Copyright
2003 by Maslennikov, Aivaz’yan, Kurskii, Spirina.
LETTERS
TO THE EDITOR
Isomerization of 1-Hexene into 2-Hexene,
Catalyzed by the Product of Magnesium Oxidation
with Molybdenum Pentachloride in Tetrahydrofuran
S. V. Maslennikov, I. A. Aivaz’yan, Yu. A. Kurskii, and I. V. Spirina
Research Institute of Chemistry, Lobachevskii Nizhny Novgorod State University, Nizhny Novgorod, Russia
Received July 8, 2002
It was found by Smirnov et al. [1] that compounds
formed by cryocondensation of magnesium vapor with
unsaturated hydrocarbons catalyze olefin isomeriza-
tion, isotope exchange, polymerization, etc. Such
transformations are not induced by magnesium halides,
Grignard reagents, and highly dispersed metal but are
catalyzed by transition metal complexes. Quantum-
chemical calculations in [1] gave evidence showing
that magnesium hydride clusters are stable as a com-
pact metal frame (tetrahedron, trigonal bipyramid).
The apparent activation energy of the reaction at
293 313 K is 30 kJ/mol, the reaction order in sub-
strate is one, and the reaction order in catalyst is two.
At 313 K and initial 1-hexene and complex II con-
centrations in THF of 3.2 and 0.03 M, respectively,
about 60 catalytic cycles occur.
It should be noted that the isomerization of
1-hexene is also catalyzed by the products of mag-
nesium oxidation with higher titanium, vanadium,
niobium, tantalum, and tungsten in THF. At the same
time, the compound formed by reaction of MoCl5
with sodium naphthalide in a 1:3 ratio in THF fails
to catalyze the isomerization of 1-hexene.
Compounds containing magnesium hydride clusters
can be obtained by oxidation of magnesium with
variable-valence metal halides in THF. Such com-
plexes have first been reported in [2, 3]. Yamamoto
et al. [2] detected the complex [VHMg2Cl2 THF] in
the postreaction mixture of vanadium trichloride and
magnesium in THF. Later we showed [4, 5] that
magnesium hydride complexes [MHnMgmCll (TGF)k]
(I) are formed by oxidation of the metal taken in a
considerable excess with higher chromium, molyb-
denum, niobium, tantalum, and tungsten halides.
Propene undergoes no polymerization at 293 K
within 48 h when exposed gaseous at a pressure of
200 or 300 mm over a solution of complex II (cII
0.05 M) in THF or toluene. The NMR spectra were
measured on a Bruker DPX-200 solution in CDCl3,
internal reference TMS [working frequencies 200 (1H)
and 50 (13C) MHz].
REFERENCES
Complexes I as dark solid amorphous materials are
easily isolated from the reaction mixtures after
removal of the solvent and excess magnesium. They
are readily soluble in THF and sparingly soluble in
benzene and toluene. Complexes I react with cyclo-
pentadiene in THF, giving transition metal derivatives
capable of catalyzing magnesium oxidation with this
unsaturated compound to form (C5H5)2Mg.
1. Smirnov, V.V., Beletskaya, I.P., Tyurina, L.A., Ber-
kovskii, G.B., Kashin, A.N., and Tarkhanov, I.T., Kinet.
Katal., 1998, vol. 39, no. 6, p. 885.
2. Yamamoto, A., Go, S., Ookawa, M., Takahashi, M.,
Ikeda, S., and Keii, T., Bull. Chem. Soc. Jpn., 1972,
vol. 45, no. 10, p. 3110.
3. Jezowska-Trzebiatowska, B. and Sobota, B., J. Orga-
nomet. Chem., 1974, vol. 76, no. 11, p. 43.
4. Maslennikov, S.V., Aivaz’yan, I.A., Usanov, A.A., and
Tsarev, M.V., Vestn. Nizhegorod. Gos. Univ., Ser.
Khim., 2001, no. 1, p. 147.
5. Ignat’ev, R.A., Maslennikov, S.V., Spirina, I.V., Ar-
temov, A.N., and Maslennikov, V.P., Zh. Obshch. Khim.,
2002, vol. 72, no. 6, p. 944.
The magnesium hydride cluster formed by oxida-
tion of excess metal with MoCl5 in THF,
[MoHMg2.8Cl2.0THF] (II), catalyzes isomerization of
1-hexene into 2-hexene.
1
Reaction progress was followed by H NMR spec-
troscopy. The ratio of trans- and cis-2-hexanes,
determined by 13C NMR spectroscopy, is 1:4.
1070-3632/03/7308-1319$25.00 2003 MAIK Nauka/Interperiodica