The synthesis of new cyclopentadienyl-containing heterobimetallic
alkoxides has been
accomplished by employing the alkoxide precursors toward
cyclopentadienyl reagents (NaCp
and (C5H5)SnCl). The equimolar
reactions of anhydrous SnX2 (X = Cl, I) and
KM2(OPri)9
(M = Zr, Hf) offer halide heterobimetallic isopropoxides
[XSn{M2(OPri)9}]2
(1, M = Hf, X =
Cl; 2, M = Hf, X = I; 3, M = Zr, X = Cl)
in quantitative yields. Both 1 and 3 react
with
NaCp in benzene−THF to give
(C5H5)Sn{M2(OPri)9}
(4, M = Hf; 5, M = Zr).
Alternatively,
4 and 5 are conveniently obtained by the
equimolar reaction of (C5H5)SnCl with
KM2(OPri)9
(M = Zr, Hf). Although the reaction (1:1) of
(C5H5)SnCl with
[KGe(OBut)3]
n
affords the
expected product
(C5H5)Sn(μ2-OBut)2Ge(OBut)
(6), the reaction with
[KPb(OBut)3]
n
shows a
transfer of cyclopentadienyl ring from tin to lead to provide
(C5H5)Pb(μ2-OBut)2Sn(OBut)
(7). The new derivatives have been readily
characterized by elemental analysis, multinuclear
(1H, 13C, 119Sn, and
207Pb) NMR studies, molecular weight measurements, and
volatility. A
single-crystal X-ray diffraction study is reported for the compounds
1, 3, and 5−7. The
solid
state structures of 1, 3, and 5
exhibit varying coordination behavior of
M2(OPri)9
- units
to
SnX+ (X = C5H5, Cl) fragments.
In the structural framework of the tert-butoxide
derivatives,
the four membered
MM‘(μ2-OBut)2 (6,
M = Ge, M‘ = Sn; 7, M = Pb, M‘ = Sn) ring
is
terminated at the metal ends by cyclopentadienyl and
tert-butoxide ligands and each of the
metals, bearing a stereochemically active lone pair, displays a
pyramidal geometry.
