It has been established that halide abstraction from several
lanthanide(III) chlorides can be effected by tin
tetrachloride. Direct treatment (1∶1) of LnCl
3
where
Ln = Ce, Gd or Yb with SnCl
4
in tetrahydrofuran
(thf) provided colourless compounds of the generic type
LnSnCl
7
(thf)
6
which have been identified
by X-ray crystallography as ionic salts
[trans-LnCl
2
(thf)
5
][SnCl
5
(thf)]. The individual seven-co-ordinate cations feature a
regular pentagonal-bipyramidal metal geometry in which a
trans-LnCl
2
unit is surrounded by five thf molecules
arranged in an equatorial plane. These co-ordinated solvent molecules
adopt the familiar ‘propeller-like’ arrangement indicative
of a skew as opposed to envelope ligand conformation. For
Ln = Ce, Ce–Cl 2.697(2), Ce–O mean 2.495(5)
Å; for Ln = Gd, Gd–Cl 2.608(2), Gd–O
mean 2.415(4) Å; for Ln = Yb, Yb–Cl
2.5375(13), Yb–O mean 2.346(4) Å. The six-co-ordinate
[SnCl
5
(thf)]
-
anions common to the
series show a two-fold axis of symmetry containing the metal atom, the
oxygen (thf) atom and a chloride atom mutually trans to
the latter. Bond distances for Ln = Ce, i.e.
Sn–O 2.276(7), Sn–Cl mean 2.399(2) Å, are typical
for the series.
已经证实,
四氯化锡可以从几种
镧系(III)
氯化物中抽取卤化物。在
四氢呋喃(thf)中用
氯化锡 4 直接处理(1∶1)LnCl 3(其中 Ln = Ce、Gd 或 Yb),可得到无色的 LnSnCl 7 (thf) 6 通式化合物,经 X 射线晶体学鉴定为离子盐 [trans-LnCl 2 (thf) 5 ][SnCl 5 (thf)]。单个七配位阳离子具有规则的五角双锥
金属几何形状,其中一个反式
氯化锰 2 单元被排列在赤道面上的五个
噻吩分子包围。这些配位溶剂分子采用了我们熟悉的 "螺旋桨式 "排列,表明
配体的构象是倾斜的,而不是包络的。对于 Ln = Ce,Ce-Cl 2.697(2),Ce-O 平均 2.495(5)埃;对于 Ln = Gd,Gd-Cl 2.608(2),Gd-O 平均 2.415(4)埃;对于 Ln = Yb,Yb-Cl 2.5375(13),Yb-O 平均 2.346(4)埃。该系列中常见的六配位[SnCl 5 (thf)] - 阴离子显示出包含
金属原子、氧原子(thf)和与后者互为反式的
氯原子的双重对称轴。Ln = Ce 的键距,即 Sn-O 2.276(7)埃,Sn-Cl 平均 2.399(2)埃,是该系列的典型键距。