On the rare earth cyanides A +LnT II(CN) 6· nH 2O, AK, Rb, Tl, NH 4, TFe(Ru,Os)

Abstract

In the rare-earth ferricyanides LnFe III(CN) 6· nH 2O ( n=5, 4) one of the two zeolitic H 2O molecules per formula unit can be replaced by the larger alkali ions A +K +, Rb +, as well as by NH 4 +. Those with the larger Ln ions crystallize in the same structure as the hexagonal archetype LaFe(CN) 6·5H 2O, whereas those with the smaller Ln adopt an orthorhombic structure which differs in detail from the orthorhombic SmFe(CN) 6·4H 2O type. For ACs the analogy holds only for LnLa, Ce, (Pr), whereas with the heavier Ln elements a yet unknown structure appears. Among the potassium salts of the Ru II and Os II analogues the archetype structure is again found with the larger rare-earth ions only. The smaller Ln ions induce a further yet unknown structure.