Chemistry Reference
In-Depth Information
+
Fig. 3.36
X-ray crystal structure of the 2D Q[8]/Rb
network:
a
an overall view;
b
a six-Q[8]-
membered ring isolated from the 2D network;
c
a trigonal-planar branch constructed from three
Q[8] molecules linked by a Rb
+
pair;
d
a trigonal-planar branch constructed from three dime-
thyl-substituted Q[5] molecules and K
+
ions, shown for comparison;
e
and
f
the superimposed
+
Rb
/Q[8]-based networks, top view and side view, respectively
composed of three Q[8] molecules, each of which are linked by a pair of Rb
+
ions, could be observed (Fig.
3.36
c). This structure is similar to that discovered
in the coordination of SQ[5]s with potassium cations (Fig.
3.36
d). When the 2D
networks are stacked upon one another, channels filled with the Rb
+
pairs are cre-
ated. Networks with identical chemical environments alternate with one another,
as shown in Fig.
3.36
e, f.
When InCl
3
was introduced into the Q[8]-Na
+
-HCl system, the obtained crys-
tal structure shows similar 2D Q[8]/Na
+
networks accompanying [In(H
2
O)
2
Cl
4
]
−
anions. Each trigonal-planar branch is accompanied by six [In(H
2
O)
2
Cl
4
]
−
anions,
and three Q[8] molecules in the trigonal-planar branch is linked by only one
Na
+
cation (Na1) (Fig.
3.37
a). The trigonal-planar branch can fuse into a six-
Q[8]-membered ring, and both portals of the ring form the rims of the six
[In(H
2
O)
2
Cl
4
]
−
anions (Fig.
3.37
b, c). Thus, the extension of the six-Q[8]-mem-
bered ring results in the formation of the 2D Q[8]/Na
+
networks (Fig.
3.37
d).
Unlike the stacking of the 2D Q[8]/Rb
+
networks, the 2D Q[8]/Na
+
network
sheets are repeatedly superimposed upon one another in exact order (Fig.
3.37
d).
The six-Q[8]-membered rings and the 12 rimmed [In(H
2
O)
2
Cl
4
]
−
anions create a
nanochannel (Fig.
3.37
e).
When the Sr
2
+
cation replaces the Rb
+
cation in the presence of transi-
tion metal ions, the Q[8]-Sr
2
+
-HCl system gives crystals with similar features.
However, a close inspection revealed that the eight-Q[8]-membered rings, and not
six-Q[8]-membered rings, are present in the 2D Q[8]/Sr
2
+
network (Fig.
3.38
a, b).
Each eight-Q[8]-membered ring is linked by eight Sr
2
+
cations (Fig.
3.38
b). The
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