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

摘要

Reaction between EuCl_2 and 2,2'-bipyrimidine (bpm) in de-oxygenated water afforded a cationic molecular complex IEuCl(bpm)_2(H_2O)_4][Cl]·H_2O (1). When performed in an organic solvent such as THF or methanol, the same reaction yielded a 3-dimensional coordination polymer of formula [EuCl_2(bpm)(MeOH)_(0.5)]_∞ (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(H_2O)_3][I]_2· 0.5bpm}∞ (3) and {{[Eu(I)(bprn)(MeOH)][I]}∞ (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.