Rationalization of the Substructures Derived from the Three Fluorite-Related [Li6(MVLi)N4] Polymorphs: An Analysis in Terms of the “Barnighausen Trees” and of the “Extended Zintl–Klemm Concept” - Inorganic 3D Structures - page 115

Table 7 Site equivalen ce s
betwe e n space groups F43 c
and

F 43 c P 43 n

8 a 2 a +6 b

P 43 n

8 b 8 e

24 c 24 i

24 d (6 c +6 d +12 f )

32 e (8 e +24 i )

48 f (2 24 i )

3.5.1 Nickel Boracite

The drawing for Ni-boracite [ 43 ] is shown in Fig. 16a , but without the O(2) atoms
in the general site 96 h . Figure 16b shows all of the

g

-Li 7 VN 4 structure. The

topological equivalence of the two is obvious.
So what about the missing O(2) atoms of the boracite drawing? Their function
provides a very elegant twist to the story! The B(1) atoms are tetrahedrally

Fig. 16 (a) The atomic array of nickel boracite Ni 3 B 7 O 13 I( a ¼ 12.016 ˚ ) viewed near the [100]
projection, but less the less the O(2) atoms, which are omitted for clarity: O(1) atoms - yellow ,I
atoms - light blue , Ni atoms - dark green , B(1) atoms - red , B(2) atoms - blue .(b) The equivalent
projection of Li 7 VN 4 ( a ¼ 9.606 ˚ ): N(1) + N(2) atoms - blue ; V(1) Li(3) atoms - yellow , Li(4)
atoms - light blue , Li(5) Li(1) atoms - dark green , Li(1) þ Li(2) atoms - red .(c) Perspective view
near [100] of the Ni 3 B 7 O 13 I structure. Ni atoms - dark green ; I atoms - light blue ; O(1) atoms -
yellow ; B(2) atoms - red , and enlarged for emphasis, O(2) atoms - blue .(d) The Ni 3 B 7 O 13 I
structure: the same projection as (c) but with the B(1)O(2) 4 tetrahedra - pink (not all shown)