Structural Systematics of Rare Earth Complexes. XV Tris(2,2′:6′,2&amp;Prime;-terpyridine)lanthanoid( <i>III</i> ) Tris(perchlorate) Complexes

Abstract

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 3 c 1, Z = 6, a 13·063(7), c 53·04(4) Å, recorded on an interim basis, with conventional R on | F | 0·081 for N o 2889 ‘observed’ ( I &amp;gt;3s( 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 Å, ß ˜ 91°, Z = 4, R being 0·045, (0·060, 0·049,) 0·047 for N o 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 N o 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.