Syntheses of lanthanide bromide complexes from oxides and the crystal structures of [LnBr3(DME)2] (Ln = Pr, Nd, Sm, Eu), [LnBr3(THF)4] (Ln = Pr, Sm) and [EuBr2(THF)5][EuBr4(THF)2]

Lanthanide bromide complexes were prepared in excellent yields by reactions of lanthanide oxides and hydrogen bromide, which was formed in situ from bromotrimethylsilane and water, in DME (DME = dimethoxyethane). The crystals for X-ray structural analyses were grown from DME and from THF (THF = tetrahydrofuran) solutions. Three bromine and four oxygen atoms from DME are coordinated to a central lanthanide atom in the crystal structures of lanthanide complexes [LnBr(3)(DME)(2)] (Ln = Pr (1), Nd (2), Sm (3), Eu (4)). Crystallization from THF resulted in two types of complexes, molecular [LnBr3(THF)(4)] (Ln = Pr (5), Sm (6)) and ionic [EuBr2(THF)(5)][EuBr4(THF)(2)] (7). Complexes 1, 4, 5 and 7 are the first crystallographically characterized water-free complexes of praseodymium or europium tribromides. (C) 2004 Elsevier Ltd. All rights reserved.