Chemistry Reference
In-Depth Information
2.16
Alkoxides of Copper, Silver, and Gold
2.16.1
Copper
The structures of various Cu(
I
)andCu(
II
) alkoxo complexes have been reported
(Table 4.15).
The first homoleptic Cu(
I
) alkoxide structure determined was the tetranuclear
tert
-
butoxide [Cu
4
-OBu
t
4
] which has a planar Cu
4
O
4
ring (Fig. 4.54) with linear
two-coordinated copper rather than the cubane-like structure which might have been
anticipated.
420
Addition of PPh
3
produced the dimer [Cu
2
-OBu
t
2
PPh
3
2
] with
three-coordinated copper. The Cu
2
P
2
O
2
core is not coplanar owing to the dihedral
angle of 143
.
4
Ž
about the O
....
Oaxis.
421
Likewise the triphenylsiloxo group gave
the tetranuclear [Cu
4
-OSiPh
3
4
] with linear two-coordinated Cu(
I
) and the dinuclear
[Cu
2
-OSiPh
3
2
PMe
2
Ph
2
].
422
Even the very bulky
Bu
t
O
2
Ph
SiO ligand produces
the tetranuclear [Cu
4
f
-OSi
OBut
2
Phg
4
] structure with the planar Cu
4
O
4
core and
linear two-coordinated Cu(
I
).
423
Numerous
structures
of
alkoxo
copper(
II
)
complexes
have
been
deter-
[O
CH
2
4
N
D
C
Me
CH
2
C
CF
3
2
O]
2
mined.
The
tridentate
diolate
ligands
and
[O
CH
2
3
N
D
C
Me
CH
2
C
CF
3
2
O]
2
gave
binuclear
complexes
[Cu
2
f
-
O
CH
2
n
N
D
C
Me
CH
2
C
CF
3
2
Og
2
](
n
D 4
,
3).
Each
molecule
has
square
planar
Cu(
II
) atoms with an essentially near planar ONCu
-O
2
CuNO framework.
424
In the dinuclear fluorinated iminoalkoxo complex [Cu
2
f
-
OC
CF
3
2
CH
2
C
Me
D
N
CH
2
5
N
D
C
Me
CH
2
C
CF
3
2
Og
2
], in which the tetraden-
tate ligands bridge the two copper(
II
) centres, the coordination around the metal
is
tetrahedral.
425
distorted
planar
towards
Other
related
Cu(
II
)
complexes
are
PPh
4
2
[CufOC
CF
3
2
OH
g
4
]
2
,
427
[CufOC
CF
3
2
CH
2
CHNHRg
2
](RD menthyl),
426
(L D triazacyclododecene),
406
[CufO
2
C
CF
3
2
gL]
[CufOC
CF
3
2
OC
CF
3
2
Og
Me
2
NC
2
H
4
NMe
2
],
428
and [CufOC
CF
3
2
CH
2
C
O
DCHC
CF
3
2
OHg
Me
2
NC
2
NMe
2
].
407
Bis-chelated complexes have been obtained using aminoalkoxo
ligands,
e.g.
[CufOCH
2
C
Me
2
NH
2
g
2
],
429
[CufOCH
Me
CH
2
NMe
2
g
2
], and
[CufOCH
2
CH
2
N
Me
CH
2
CH
2
NMe
2
g
2
].
430
In the latter compound the Cu(
II
)isfive-
coordinated (distorted square pyramidal) because one ligand is tridentate and the other
one bidentate. The mixed ligand complex [f
CF
3
3
COgCu
-OBu
t
2
Cu
-OBu
t
2
Cu
-OBu
t
2
CufOC
CF
3
3
g] has a novel linear structure with the inner copper atoms
Figure 4.54
Structure of
[Cu
4
-OBu
t
4
](Hatoms
omitted).
