Structural Systematics of Rare Earth Complexes. V. The Hydrated 1 : 1 Adducts of 2,2′:6′,2″-Terpyridine With the Lanthanoid(III) Chlorides

Abstract

Detailed examination of the strucures of the title salts, (tpy)LnCl₃.xH₂O, across the totality of the rare earth series shows a remarkable interplay of structural type and detail. The predominant phase is the previously studied monoclinic Cm array, a ≈ 7.5, b ≈ 16.6, c ≈ 9.8 Ǻ, β = 90.2°, V ≈ 2200 Ǻ₃, Z = 2 formula units. For the initial members of the series (La → Nd ), x is 8; for Dy → Er and Lu, x = 7 is accommodated within the same lattice, as are intermediate degrees of hydration for Sm → Gd . A second monoclinic phase, P 2₁/c, a ≈ 11.6, b ≈ 13.9, c ≈ 13.8 Ǻ, β ≈ 92.3°, V ≈ 2200 Ǻ³, Z = 4 formula units, is found for Yb and Lu (x = 7); the same phase but with β acute (a ≈ 11.3, b ≈ 14.5, c ≈ 13.3 Ǻ, β ≈ 82.2°, V ≈ 2140 Ǻ³, Z = 4 formula units) is found for Tm (and Y) (x = 6). A less hydrated binuclear phase, x=1, has also been observed for Sm , a 10.179(3), b 9.928(4), c 9.748(4) Ǻα 112.61(3), β 109.85(3), γ 94.72(3)°, V 829.3 Ǻ³, Z = 1 dimer.