Chemistry Reference
In-Depth Information
of Ba
-OPr
i
2
Cd
-OPr
i
2
Cd
-OPr
i
2
Ba, containing four-coordinated (distorted
tetrahedral) Cd with each Ba capped with a quadridentate chelating M
2
OPr
i
9
moiety.
In the trinuclear complex [
Pr
i
O
4
Nb
-OPr
i
2
Ba
HOPr
i
2
-OPr
i
2
Nb
OPr
i
4
]the
three octahedrally coordinated metals are nonlinear (NbBaNb, 137
Ž
) owing to the
cis
configuration of the terminally coordinated PriOH ligands on the central barium
ion.
496
,
497
Hydrogen bonding involving the isopropanol OH proton and a terminal
Nb-OPr
i
oxygen causes a significant lengthening of the Nb-O bond.
A number of barium copper alkoxo compounds have been characterized. The
first homoleptic complex reported was the volatile species [Baf
-
OCMe
CF
3
2
g
4
fCuOCMe
CF
3
2
g
2
] in which the central Ba ion is coordinated by four
oxygens and eight fluorines. The Cu(
II
) is three-coordinated (trigonal planar).
498
In the
hexanuclear barium copper(
I
) complex [Ba
2
-OR
2
f
,
2
-OR
Cu
-OR
Cu
ORg
2
]
R D CEt
3
the two Ba ions are bridged by two alkoxo groups and chelated by two
RO
Cu
2
OR
2
moieties containing linear two-coordinated copper(
I
)atoms.
465
The
Ba
2
O
2
ring is near normal to the BaOCuOCuOBaOCuOCuO plane.
Some mixed ligand complexes involving functionalized alkoxo ligands have been
reported. In [Ba
2
Cu
2
3
,
2
-OC
2
H
4
OMe
4
,
2
-acac
2
acac
2
MeOC
2
H
4
OH
2
]the
metals are arranged in a rhomboid structure with four
3
-alkoxo ligands in a plane with
the two CuO
2
acac
units. The Cu(
II
)atomsarefive-coordinated (square pyramidal)
whilst the Ba ions are nine-coordinated (distorted capped rectangular antiprism).
In the pentanuclear [BaCu
4
3
-OC
2
H
4
OMe
2
-OC
2
H
4
OMe
2
OC
2
H
4
OMe
2
Bu
t
COCHCOBu
t
4
] the Ba ion is ten-coordinated and the binuclear Cu
2
O
9
units
are confacial bi-octahedra which act as
4
-chelating groups to the barium.
500
In the
binuclear species [
2
-HOC
2
H
4
OH
3
Ba
,
2
-O
2
C
2
H
4
2
Cu] the barium ion is eight-
coordinated (distorted cubic) and the copper four-coordinated (square planar).
501
The trinuclear mixed ligand complex [Ba
2
Cu
3
,
2
-OCNMeCH
2
NMe
2
2
,
2
-
Bu
t
COCHCOBu
t
2
Bu
t
COCHCOBu
t
2
Pr
i
OH
2
] is unsymmetrical in structure. One
eight-coordinated barium is bonded to two terminal Pr
i
OH ligands, the oxygens of
two
3
,
2
-OCHMeCH
2
NMe
2
ligands and two diketonates whilst the other is seven-
coordinated to one chelating diketonate, two bridging diketonates, one chelating
aminoalkoxide, and the
3
-O of another chelating aminoalkoxide. The Cu(
II
)atom
is five-coordinated (square pyramidal) to two
3
-O atoms of aminoalkoxides, one
nitrogen, and a chelating diketonate.
502
In the barium dialuminium tetrakis-1,2-ethanediolate [Ba
,
2
-
O
2
C
2
H
4
2
Al
2
O
2
C
2
H
4
2
] a two-dimensional layer polymer is formed by bi-trigonal
bipyramidal Al
2
,
2
-O
2
C
2
H
4
2
dimers linked
via
four diolate ligands to four neigh-
bouring
dimers
with
the
barium
ions
surrounded
by
four
dimer
units
in
an
eight-coordinated structure.
503
3.3
Yttrium and Lanthanide Bimetallic Alkoxides
3.3.1
Yttrium
Some mixed ligand yttrium heterometal alkoxides have been characterized. In the tri-
nuclear complex [YCu
2
3
,
2
-OC
2
H
4
OMe
,
2
-OC
2
H
4
OMe
2
hfd
2
thd
2
]
hfd D
CF
3
COCHCOCF
3
;thdD Bu
t
COCHCOBu
t
the Y is bonded to eight oxygens (av. 2.39 A)
and weakly to a ninth (2.79 A) whilst one Cu is four-coordinated (square planar) and the
