Synthesis and structural analysis of a homogeneous series of anhydrous rare-earth-metal perchlorates

The reaction of Cl2O6 with anhydrous or hydrated metal(III) chlorides, nitrates or hydrated perchlorates leads to anhydrous metal perchlorates M(ClO4)3(M = Y, La, Nd, Sm, Gd or Er). The complexes are isostructural and crystallise in the monoclinic system (space group P21/m): 8.219(6) < a < 8.384(6), 5.602(1) < b < 5.869(9), 7.329(4) < c < 7.481(2)Å, 102.88(4) < β < 104.09(5)°, 328.957 < U < 357.110 Å3. Vibrational spectroscopic data show a bridging tridentate co-ordination of ClO4, and a polymeric layered structure, derived from that of UCl3, is suggested. Intense fluorescence of Er3+ in the Er(ClO4)3 complex has been observed. The synthesis and characterisation of three salts, (NO2)3Er(ClO4)6, ClO2Er(ClO4)4 and (ClO2)0.33La(ClO4)3.33, are also described.