Syntheses of lanthanide bromide complexes from oxides and the crystal structures of [LnBr 3(DME) 2] (Ln = Pr, Nd, Sm, Eu), [LnBr 3(THF) 4] (Ln = Pr, Sm) and [EuBr 2(THF) 5][EuBr 4(THF) 2

Abstract

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 [LnBr 3(THF) 4] (Ln = Pr ( 5), Sm ( 6)) and ionic [EuBr 2(THF) 5][EuBr 4(THF) 2] ( 7). Complexes 1, 4, 5 and 7 are the first crystallographically characterized water-free complexes of praseodymium or europium tribromides.