om9605185_si_001.pdf (997.45 kB)
tert-Amyl Compounds of Aluminum and Gallium: Halides, Hydroxides, and Chalcogenides
journal contribution
posted on 1996-12-24, 00:00 authored by C. Jeff Harlan, Edward G. Gillan, Simon G. Bott, Andrew R. BarronThe reaction of AlCl3 with 3 equiv of the
tert-amyl Grignard reagent
(Me2EtC)MgCl yields
the monomeric trialkyl compound
Al(CMe2Et)3 (1).
Reaction of compound 1 with MeCN
and [PPN]Cl yields the Lewis acid−base complexes
Al(CMe2Et)3(MeCN) (2)
and [PPN][AlCl(CMe2Et)3] (3), respectively.
The hydrolysis of Al(CMe2Et)3 in
hexane results in the formation
of the trimeric hydroxide
[(Me2EtC)2Al(μ-OH)]3
(4), which is converted to the dimer
[(Me2EtC)2Al(μ-OH)]2
(5) upon heating. The reaction of
Al(CMe2Et)3 with H2S at
room
temperature yields the cubane compound
[(Me2EtC)Al(μ3-S)]4
(6). If the reaction is carried
out at 0 °C, then the hexamer
[(Me2EtC)Al(μ3-S)]6
(7) may be isolated along with compound
6. The selenide analog of 6,
[(Me2EtC)Al(μ3-Se)]4
(8), is prepared directly from the reaction
of compound 1 with H2Se, while the
telluride analog,
[(Me2EtC)Al(μ3-Te)]4
(9), is prepared
by the direct reaction of compound 1 with tellurium metal.
The gallium cubane compounds
[(Me2EtC)Ga(μ3-E)]4,
(E = S (10), Se (11), Te (12)) have
been prepared from the reaction of
Ga(CMe2Et)3 with the appropriate
element. The tert-amyl compounds are compared to
their
tert-butyl analogs, and the isolation of compound
7 is used as a precedent to prepare
[(tBu)Al(μ3-S)]6
(13). A structural analysis is made of the
M4E4 cubane cores (M = Al, Ga,
In; E = S, Se, Te), and a new topological method is proposed to
predict the intracage bond
angles in group 13 cage compounds,
[(R)M(μ3-X)]n. The
molecular structures of compounds
3, 6, 8, and
10−12 have been determined by X-ray
crystallography, and a discussion of the
crystallographic problems associated with the tert-amyl
group is presented.