Europium(II) compounds: simple synthesis of a molecular complex in water and coordination polymers with 2,2′-bipyrimidine-mediated ferromagnetic interactions

Reaction between EuCl2 and 2,2'-bipyrimidine (bpm) in de-oxygenated water afforded a cationic molecular complex [EuCl(bpm)(2)(H2O)(4)][Cl]center dot H2O (1). When performed in an organic solvent such as THF or methanol, the same reaction yielded a 3-dimensional coordination polymer of formula [EuCl2(bpm)(MeOH)(0.5)](infinity) (2) in which both bpm and the chloride ions act as linkers between the Eu(II) ions. Upon replacing Cl- by I-, two coordination polymers of formula {[Eu(bpm)(2)(H2O)(3)][I](2)center dot 0.5bpm}(infinity) (3) and {[Eu(I)(bpm)(MeOH)][I]}(infinity) (4) were obtained from reaction in water and methanol, respectively. All these compounds were characterized by X-ray crystallography. Investigations of the magnetic properties revealed a weak antiferromagnetic coupling in 2, while 3 and 4 showed a weak ferromagnetic coupling at low temperature.