Chemistry Reference
In-Depth Information
2
SYNTHESIS
As discussed in several review articles
16 - 19
,
21
,
24
,
28
,
29
,
35
,
47
the procedures employed for
the synthesis of heterobimetallic alkoxides are in general similar to those utilized for the
homometallic species. Some of the heterobimetallic derivatives with reactive group(s)
(generally chloride) on the central metal atom can be conveniently converted to tri- or
higher metallic systems by treating these with different alkali alkoxometallates.
2.1
Preparative Routes to Homoleptic Heterobimetallic Alkoxides
These can be broadly sub-divided into several categories.
2.1.1
Reactions Between Component Metal Alkoxides
The formation of alkali alkoxometallates in the reactions of alkali alkoxides with those
of less basic alkoxides continues to be the most common route, although reactions of
a few other alkoxides have also been utilized for this purpose:
2.1.1.1 Preparation of alkali alkoxometallates (A-1)
Following the procedure of Meerwein and Bersin
1
and others,
30
,
31
,
33
,
34
this method has
been extended to the bimetallic alkoxides of alkali metals (Lewis bases) with those of
less basic metals and metalloids, beryllium,
48
,
49
zinc,
48
,
50
boron,
51
aluminium,
1
,
34
,
52
,
53
gallium,
52
tin(
II
),
54 - 56
tin(
IV
),
57
antimony(
III
),
58
,
59
bismuth,
59
titanium,
41
,
60
niobium(
IV
),
61
zirconium,
2
,
41
,
62 - 64
thorium,
52
niobium(
V
),
52
,
65 - 67
tantalum(
V
)
52
,
65
and copper.
68
Equa-
tions (3.1) - (3.3) reflect a few typical reactions used in the synthesis of bimetallic alkox-
ides involving alkali metals (M):
MOR C M
0
OR
x
! MM
0
OR
x
C1
3
.
1
x
D 1; M
0
D Cu
I
;MD Na
,
R D Bu
t
.
x
D 2; M
0
D Sn
II
;MD Li
,
Na
,
K
,
Rb
,
Cs; R D Bu
t
.
x
D 3; M
0
D Al
,
Sb
III
,
Bi
III
;MD Li
,
Na
,
K
,
Rb
,
Cs
.
R D Et
,
Pr
i
,
Bu
t
.
x
D 4; M
0
D Ti; M D Li
,
Na
,
K; R D Pr
i
.
M
0
D Zr
,
Sn
IV
;MD K
,
Rb
,
Cs; R D Bu
t
.
M
0
D Nb
IV
;MD Na; R D Pr
i
.
x
D 5; M
0
D Nb
,
Ta; M D Li
,
Na
,
K
,
Rb
,
Cs;
R D Me
,
Et
,
Pr
i
,
Bu
t
,
CH
2
CMe
3
,
CH
2
SiMe
3
.
MOR C 2M
0
OR
4
! MM
0
2
OR
9
3
.
2
M
0
D Ti
,
Zr
,
Hf
,
Sn
IV
,
Th; M D Li
,
Na
,
KTl
I
;RD Et
,
Pr
i
.
M
0
D Nb
IV
;MD Na; R D Me
.
2MOPr
i
C 3Zr
OPr
i
4
! M
2
Zr
3
OPr
i
14
3
.
3
[M D Na
,
K]
