Chemistry Reference
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being four-coordinated (compressed tetrahedral) and the outer ones three-coordinated
(trigonal planar). The trinuclear species [Cu
3
OBu
t
4
fOC
CF
3
3
g
2
] probably has a
linear structure too.
431
In the tetranuclear compound the bridging Cu-O bonds to the
three-coordinated Cu are shorter (1.86 A) than those to the four-coordinated copper
(av. 1.95 A). The mononuclear complexes [Cu
hfip
2
(tmed)] and [Cu
hftb
2
tmed
]
(hfip D OCH
CF
3
2
,hftbD OC
Me
CF
3
2
,tmedD Me
2
NC
2
H
4
NMe
2
) have distorted
square planar Cu(
II
) and are appreciably volatile.
432
The mixed ligand tetranuclear species [Cu
4
3
,
1
-OC
2
H
4
OPr
i
4
acac
4
]hasa
cubane-like Cu
4
O
4
core and with the chelating acac ligand each Cu(
II
)isfive-
coordinated (distorted square pyramidal).
433
The tridentate ligand 1,1-bis-(2-pyridyl)-1-methoxy methoxide reacted with Cu(
II
)
in methanol in the presence of pyrazolate ions to form the tetranuclear complex
[Cu
4
L
2
prz
4
MeOH
2
]
2C
ClO
4
2
(L D MeOC
C
5
H
4
N
2
O; prz D C
3
H
3
N
2
)inwhich
two coppers are square planar and two are square pyramidal (Fig. 4.55). The di-cation
is centrosymmetric, consisting of a dinuclear unit with two coppers bridged by the
bridging bis-chelating alkoxo ligand and one bridging pyrazolate ion, linked to another
dinuclear unit by two interdimer bridging pyrazolates. The five-coordinated Cu has a
coordinated methanol ligand.
434
The tridentate aminoalkoxo ligand (Me
2
NCH
2
2
CHO
which also acts as a bis-chelating bridging ligand forms the trinuclear complex
[Cu
3
f
-OCH
CH
2
NMe
2
2
g
4
MeOH
Cl
2
]inwhichthe3five-coordinated Cu(
II
)atoms
are in a nonlinear array.
435
A novel tetranuclear structure is exhibited by the mixed ligand complex
[Cu
4
-OMe
4
,
2
-O
2
CMe
4
]. The four copper atoms in a plane are alternately
double bridged by
-OMe and
,
2
-O
2
CMe ligands, and the molecule exhibits strong
antiferromagnetic behaviour.
436
Figure 4.55
Structure of [Cu
4
f
-
OC
C
5
H
4
N
2
OMe
g
2
-N
2
C
3
H
3
4
MeOH
2
]
2C
( D Cu, D O; D N; H atoms omitted).
