Author:
Deacon Glen B.,Feng Tiecheng,Junk Peter C.,Meyer Gerd,Scott Natalie M.,Skelton Brian W.,White Allan H.
Abstract
Treatment of lanthanum metal with
CH2Br2 or
CH2I2 in tetrahydrofuran (thf)
under ultrasound conditions yields the corresponding
[LaX3(thf)4] (X =
Br, I) complexes in good yield. Recrystallization of
[LaBr3(thf)4] from
1,2-dimethoxyethane (dme) or bis(2-methoxyethyl) ether (diglyme) generates
[LaBr2(µ-Br)(dme)2]2
and
[LaBr2(dig-lyme)2][LaBr4(diglyme)].
Treatment of lanthanoid metals with hexachloroethane in dme yields
[LnCl3(dme)2] (Ln
= La, Nd, Er or Yb) and in acetonitrile
[YbCl2(MeCN)5]2[YbCl3(MeCN)(-Cl)2YbCl3(MeCN)].
The reaction of Yb metal pieces with 1,2-dibromoethane in thf and dme gave
single crystals of
[YbBr3(thf)3] and
[YbBr3(dme)2],
respectively. The X-ray determined structure of
[LaBr3(thf)4] shows a
seven-coordinate monomer with pentagonal-bipyramidal stereochemistry and
apical bromide ligands. For
[YbBr3(thf)3], a
monomeric structure with mer-octa-hedral stereochemistry
is observed. In
[LaBr2(µ-Br)(dme)2]2,
two eight-coordinate La centres are linked by two bridging bromides. The dme
ligands have a trans relationship to each other, and
cis terminal bromides are transoid
to the bridging bromides with dodecahedral stereochemistry for La. By
contrast, the 1: 1.5 diglyme adduct is found to be ionic
[LaBr2(diglyme)2][LaBr4(diglyme)],
with an eight-coordinate bicapped trigonal-prismatic lanthanum cation and a
seven-coordinate pentagonal-bipyramidal lanthanum anion. In the cation, the
bromide ligands are cis to each other, and in the anion,
two bromides are equatorial and two are axial. In
[YbBr3(dme)2],
[YbCl3(dme)2] and
[ErCl3(dme)2], a
seven-coordinate pentagonal-bipyramidal arrangement exists with apical halogen
ligands. Far-infrared data, and in particular the absence of absorptions
attributable to Ì(La–Clter), suggest that
[LaCl3(dme)] is polymeric with six bridging
chlorides per lanthanum. For
[YbCl2(MeCN)5]2[YbCl3(MeCN)(-Cl)2YbCl3-(MeCN)],
a remarkable ionic structure, with pentagonal-bipyramidal
[YbCl2(MeCN)5]+
cations and octahedral di-nuclear
[YbCl3(MeCN)(-Cl)2YbCl3(MeCN)]2–
counter ions, is observed. In the former, chloride ligands are apical, while
the MeCN ligands of the latter are transoid.
Cited by
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