Die Kristallstrukturen von Li[PF₆] und Li[AsF₆]: Zur Kristallchemie von Verbindungen A[E^VF₆]

Li[PF6] (rhombohedral, R (3) over bar; a = 493.2(2), c = 1265.8(4) pm; Z = 3) and Li[AsF6] (rhombohedral, R (3) over bar; a = 501.6(1), c = 1302.8(4) pm; Z = 3) are isotypes of the Li[BiF6] structure. The E(?)V-elements P(As) as well as lithium are in a nearly perfect octahedral coordination by fluorine. The crystal structures of the fluoro-compounds A[E(V)F(6)] (A = Li, Na, K, Rb, Cs; E(V) = P, As, Sb, Bi) can be divided in two groups: i. with A and E(V) in a NaCl like arrangement and ii. with A and E(V) in a CsCl like arrangement. The coordination numbers (CN) of the A-sites (CN between 6 and 12) depend on the ratio of radii r(E(V5+))/r(A(+))