Hydrated Lanthanoid Complexes of 5-(2'-Pyridyl)tetrazole Formed in the Presence of Dimethyl Sulfoxide

Abstract

Reaction of DMSO solvates of lanthanoid nitrates or perchlorates with 5-(2'-pyridyl)tetrazole (pytz) and triethylamine in organic solvents resulted in the unexpected crystallization of hydrates, rather than DMSO solvates. This was confirmed by the structural characterization of [Eu(pytz)3(H2O)3]. Decreasing the metal:ligand ratio in the reaction mixture resulted in the crystallization of a complex salt formulated as [Y(pytz)2(H2O)4](pytz).(Hpytz).4H2O; once again DMSO was absent from the product. Interestingly, the omission of base from one reaction resulted in the serendipitous crystallization of Hpytz in a zwitterionic form, unlike the neutral ligand structure reported previously.