Chemistry Reference
In-Depth Information
dinuclear
complex
[(ditox)
2
Nd
-ditox
2
Nd(ditox)
2
CH
3
CN
]
was
formed
having
1 five-coordinated and 1 four-coordinated metal in the molecule.
132
Dinuclear complexes with five-coordinated Nd (distorted trigonal bipyramids) were
obtained using the di-isopropylcarbinolate [Nd
2
-OCHPr
i
2
OCHPr
i
2
4
(thf)
2
]and
[Nd
2
-OCHPr
i
2
2
OCHPr
i
2
4
C
5
H
5
N
2
]. When the THF ligands were replaced by
dimethoxyethane (DME) a chain polymer was formed with the DME ligands linking
-
dinuclear units in [Nd
2
-OCHPr
i
2
2
OCHPr
i
2
4
MeOCH
2
CH
2
OMe
]
n
.
133
The mixed
ligand mono-anion [Nd(OSiMe
3
fN
SiMe
3
2
g
3
]
has a distorted tetrahedral Nd.
134
2.7.5
Samarium
Several organosamarium alkoxides have been structurally characterized. In the di-
nuclear molecule [
C
5
Me
5
2
Sm
-O
2
C
16
H
10
Sm(C
5
Me
5
2
] each bis-pentamethylcyclo-
pentadienyl samarium moiety is bonded to an oxygen of the dihydroindenoindene diolate
bridging ligand giving rise to three- or seven-coordination depending on whether the
C
5
Me
5
ligand is counted as monodentate or tridentate.
Similarly the THF adduct [(thf)
C
5
Me
5
2
Sm
-O
2
C
16
H
10
Sm
C
5
Me
5
2
(thf)] is
either four- or eight-coordinated.
135
Similar geometry is found in the mononuclear
complex [
C
5
Me
5
2
Sm(OC
4
H
8
C
5
Me
5
(thf)].
136
In [
thf
C
5
Me
5
2
Sm
-OSiMe
2
OSiMe
2
O
Sm(C
5
Me
5
2
(thf)] the two
C
5
Me
5
2
Sm
thf)
moieties are linked by the tetramethyldisiloxane diolate bridging ligand.
137
Using the
potentially tridentate (ON
2
) ligand L D OC(Bu
t
2-CH
2
NC
5
H
3
Me-6
2
the novel five-
coordinated complex SmL
2
was obtained with two ligands acting as bidentate, with
trans
oxygen and nitrogen donor atoms in the basal positions of a distorted square
pyramid, with the third ligand's oxygen occupying the axial position as a monodentate
ligand.
138
2.7.6
Europium and Dysprosium
The only alkoxo europium complex reported to date is the dimeric [
C
5
Me
5
2
Eu
2
-
OBu
t
2
OBu
t
2
]
139
which was found to be isostructural with the fully characterized
yttrium analogue.
112
A
five-coordinated
(TBP)
mononuclear
dysprosium
complex
[Dy(OCHBu
t
2
)
3
(CH
3
CN)
2
]
132
has also been structurally characterized (Table 4.7).
2.7.7
Ytterbium
Complexes of both Yb(
II
)andYb(
III
) have been structurally characterized. The mixed
ligand Yb(
II
) complex [Yb
2
-OCBu
t
3
2
fN
SiMe
3
2
gfN
SiMe
3
2
g
2
] is dimeric with
bridging alkoxo ligands giving the familiar pseudo-tetrahedral structure.
140
The pseudo-
tetrahedral configuration is also present in the mononuclear Yb(
II
) complex [Yb
OCBu
t
3
2
(thf)
2
].
140
The
dinuclear
organoytterbium
complex
has
bridging
ethoxo
groups and coordinated diethylether ligands.
141
The mixed ligand complex [YbfOC
Bu
t
2-CH
2
NC
5
H
3
Me-6g
2
fN
SiMe
3
2
g]
involves a five-coordinated Yb(
III
) ion with two bidentate functionalized alkoxo ligands
and a terminal (axial) bis-trimethylsilylamide.
138
Another five-coordinated Yb(
II
)dimer
