Chemistry Reference
In-Depth Information
Fig. 3.17
X-ray crystal structures of a 1D polymer formed through direct coordination of
HCyHQ[6] molecules and Sm
3
+
cations
polymers have been crystallographically characterized and have been observed
to have some unique features. The two Q[6] complexes (Ce and Gd) involve per-
rhenate encapsulation [
14
]. In the Q[6]/Ce
3
+
complex, there are two different
Q[6]-based molecular capsules that include a perrhenate anion and three differ-
ent coordinated Ce
3
+
cations (Fig.
3.18
a). Each Ce1 and Ce2 cation around the
first Q[6] molecule is bound to three carbonyl groups, but two glycoluril units
are shared by the cations in this case. Moreover, Ce1 is bound to two carbonyl
groups of the second Q[6] molecule. The Ce3 cation is bound to one carbonyl
donor from the first Q[6] molecule and to three carbonyl groups of the second
Q[6] molecule, with one glycoluril unit in common with Ce1. Both Ce1 and Ce3
are bridging two Q[6] molecules. Considering the Q[6] ligands, one Q[6] mole-
cule is bound to three cations, with Ce2 at one portal, Ce1 and Ce3 at the other
portal, and the other Q[6] molecule to the two cations Ce1 and Ce3 on its two
sides. This bonding scheme results in the formation of a strongly sinuous coordi-
nation polymer (Fig.
3.18
a). A monodentate-bidentate bridging of the two Q[6]
molecules by two Gd
3
+
cations results in the formation of a 1D coordination poly-
mer. Two independent Gd
3
+
cations, Gd1 and Gd2, are located at 1.630(12) and
1.540(12) Å from the mean carbonyl oxygen plane of the associated bidentate por-
tal. The coordination sphere of both cations is linked by two perrhenate ions, one
of which is bound to Gd1 included in the Q[6] cavity (Fig.
3.18
b). In the pres-
ence of 3-sulfobenzoate, two isomorphous complexes containing Ln (Ln
=
Ce or
Nd) were obtained. These complexes display the 1D feature of coordination by the
monodentate sulfonate group only. A columnar assembly is formed by coordina-
tion of each metal ion to two Q[6] molecules, with the 3-sulfobenzoate ligand hav-
ing no role in the 1D polymer formation (Fig.
3.18
c) [
42
].
A complex has been obtained from the hydrothermal reaction of uranyl nitrate
with long-chain alkyldicarboxylic acids (HOOC-(CH
2
)
8
-COOH, denoted here
as H
2
C10) in the presence of Q[6], and dimethylformamide (DMF). This reac-
tion generates dimethylammonium cations and additional Sr
2
+
ions in situ [
43
].
The complex, [Sr
2
Q[6](H
2
O)
8
(DMF)
2
][(UO
2
)
8
O
4
(C10)
6
], includes columns built
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