Chemistry Reference
In-Depth Information
Table 5 Topological indices in the underlying nets of
a
,
b
-Zn
3
(BO
3
)
2
polymorphs and some
related binary compounds
a
Compound
Net point symbol
Coordination sequence
{4
6
.6
9
}
2
{4
3
.6
3
}
3
a
-Al
2
O
3
Al: 6 13 39 46 105
O:416266670
{4
5
.6
9
.8}
2
{4
2
.6
4
}
2
{4
3
.6
3
}
Rh
2
O
3
-HP
Rh: 6 14 42 50 114
O: 4 16-17 28 70-72 76
{4
5
.6
8
.8
2
}{4
6
.6
8
.8}{4
3
.6
3
}{4
4
.6
2
}
2
a
-Zn
3
(BO
3
)
2
B(1-4): 6 12-13 37-41 45-49 107-111
Zn(1-6): 4 16-17 25-27 66-69 71-76
{4
5
.6
9
.8}
2
{4
2
.6
4
}{4
4
.6
2
}
2
b
-Zn
3
(BO
3
)
2
B(1-2): 6 13 40 48 111-112
Zn(1-3): 4 16-18 26-27 65-74 74-75
a
The indices of metal atoms and the corresponding orthoborate anions are bold; the ranges of terms
of the coordination sequences are given for crystallographically nonequivalent atoms
Fig. 9 Topological
resemblance between UCl
3
and Tl
3
BO
3
crystal structures
Table 6 Underlying nets in nitrates
Underlying net
Nitrate
Correspondence NO
3
coordination
type
T
6
;T
33
pcu-b (NaCl)
MNO
3
(M
¼
Li, Na, K, Ag)
Normal
T
33
nia (NiAs)
a
-KNO
3
Anti
T
34
FeB
KNO
3
-IV
Anti
T
44
;T
62
;T
71
;T
8
bcu (CsCl)
MNO
3
(M
¼
Rb, Cs, Tl)
Normal
T
3
;T
21
;T
03
pyr (FeS
2
)
M(NO
3
)
2
(M
¼
Ca, Sr, Ba, Mn, Co,
Normal
Ni, Cd)
B
2
mog (SiO
2
,
moganite)
b
-Cu(NO
3
)
2
Normal
and orthoborates, small cations (Li and Na) provide the pcu-b motif (Fig.
3
), while
a
contrast to other compounds with triangular anions, nitrates containing the largest
M
+
cations (Rb, Cs, Tl) follow the denser 8,8-coordinated CsCl motif that was
phases at ambient conditions. In the former case, the high pressure gives rise to
increase in the coordination of anions (from T
8
,T
71
to T
62
,T
44
for RbNO
3
or
CsNO
3
). The trend is reversed for the high-temperature phase KNO
3
-III that has
