Chemistry Reference
In-Depth Information
2.16.2
Silver and Gold
Although several alkoxo complexes of Ag(
I
)andAu(
I
) have been prepared, usually
stabilized by organophosphine supplementary ligands, no X-ray structures have yet
been reported.
2.17
Alkoxides of Zinc, Cadmium, and Mercury
2.17.1
Zinc
The first organozinc alkoxo compound structurally characterized was the tetrameric
[Me
4
Zn
4
3
-OMe
4
] (Fig. 4.56) which has the cubane-like Zn
4
O
4
core with tetra-
hedrally coordinated zinc (Table 4.16, p. 332).
437
The
tert
-butoxide has been shown to
adopt a similar structure in [Me
4
Zn
4
3
-OBu
t
4
].
438
In the heptanuclear molecule [Zn
3
-OMe
6
ZnMe
6
], which is centrosymmetric,
two Zn
4
O
4
cubanes are fused through one octahedrally coordinated zinc giving a
dicubane structure.
439
The steric effect of bulky ligands led to the formation of the
dimer [Zn
2
-OCEt
3
2
fN
SiMe
3
2
g
2
] containing three-coordinated (trigonal planar)
zinc.
440
Using the tridentate functionalized alkoxo ligand the mononuclear octahedral
complex [Zn
1,4,7-
3
-OCH
D
CNMeCH
2
CH
2
NMe
2
2
] was obtained with the donor
oxygen atoms
trans
to one another.
440
The dimeric complex [EtZnf
,
2
-OC
Me
D
CHNEtBu
t
g
2
ZnEt] has four-coordinated
zinc.
441
The asymmetric dimer [f
2
-
Bu
t
O
3
SiOgZnf
-OSi
OBu
t
3
gf
,
2
-
OSi
OBu
t
3
gZnfOSi
OBu
t
3
g] is of interest in exhibiting four different coordinating
modes for the tri-
tert
-butoxy siloxo ligand (Fig. 4.57).
442
2.17.2
Cadmium
Two alkoxo cadmium structures have been reported. The bifunctional methoxyethoxo
ligand gave rise to the nonanuclear complex [Cd
9
OC
2
H
4
OMe
18
]
MeOC
2
H
4
OH
2
containing six-coordinated metal atoms.
443
The ligand is present in five different
coordination modes as in [Cd
9
3
,
2
-OR
6
3
,
1
-OR
2
,
2
-OR
6
,
1
-OR
2
OR
2
]
(OR D OC
2
H
4
OMe) with the hydrogen of two lattice alcohol molecules bonded
to
the
terminal
alkoxo
groups
(Fig. 4.58).
By
using
the
bulky
potentially
C
C
C
O
Zn
C
Zn
O
Zn
O
C
C
O
Zn
C
C
Figure 4.56
Structure
of
[MeZn
3
-
OMe
]
4
(H atoms omitted).
