Structural Systematics of Rare Earth Complexes. XV Tris(2,2′:6′,2″-terpyridine)lanthanoid(III) Tris(perchlorate) Complexes

Room-temperature single-crystal X-ray structure determinations of the 1 : 3 adducts of the trivalent lanthanoid perchlorates with 2,2′:6′,2″-terpyridine (‘tpy’) as crystallized from acetonitrile are recorded. The Ln = La complex is the only one of its structural type, being modelled as La(ClO4)3/tpy/MeCN/H2O (1 : 3 : 2 :2/3), trigonal P 3c1, Z = 6, a 13·063(7), c 53·04(4) A, recorded on an interim basis, with conventional R on |F| 0·081 for No 2889 ‘observed’ (I >3σ(I)) reflections. For Ln = Ce, (Pr, Sm,) Eu and, by presumption, other intermediate members, a monosolvate is found, monoclinic P 21/n, a ≈ 9·3, b ≈ 21·1, c ≈ 24·7 A, β ≈ 91°, Z = 4, R being 0·045, (0·060, 0·049,) 0·047 for No 4420, (4199, 3931,) 3713. The Ln = Eu adduct has also been obtained unsolvated in a form representative of Ln = Eu, Lu and, by presumption, intermediate members, as well as Y, which is monoclinic C 2/c, Z = 4, R being 0·051, 0·044, 0·061 for No 4386, 4407, 3713. All monoclinic systems are of the form [Ln(tpy)3] (ClO4)3(.S), Ln being nine-coordinate, and in the case of the C 2/c phase lying on a crystallographic 2 axis. The Ln = La adduct was modelled with three independent cations, all with crystallographic 3 symmetry, two with their coordination number augmented by the approach of solvent along the 3 axis.