Résumé
The reaction of Cl
2
O
6
with anhydrous or hydrated metal(
III
) chlorides, nitrates or hydrated perchlorates leads to anhydrous metal perchlorates M(ClO
4
)
3
(M = Y, La, Nd, Sm, Gd or Er). The complexes are isostructural and crystallise in the monoclinic system (space group
P
2
1
/
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 Å
3
. Vibrational spectroscopic data show a bridging tridentate co-ordination of ClO
4
, and a polymeric layered structure, derived from that of UCl
3
, is suggested. Intense fluorescence of Er
3+
in the Er(ClO
4
)
3
complex has been observed. The synthesis and characterisation of three salts, (NO
2
)
3
Er(ClO
4
)
6
, ClO
2
Er(ClO
4
)
4
and (ClO
2
)
0.33
La(ClO
4
)
3.33
, are also described.