In situ Synthesis, Crystal Structures, and Characterization of Three Milrinone Tetrazolyl Complexes

In situ [2+3] cycloaddition reactions of milrinone [= 3-cyano-6-methyl-5-(4-pyridyl)-2-pyridone] with sodium azide in the presence of MnCl2 center dot 4H2O, FeSO4 center dot 7H2O, or CoCl2 center dot 6H2O as Lewis acids, gave three new complexes {[Mn(Mitz)2(H2O)2]center dot(H2O)} (1), {[Fe(Mitz)2(H2O)2]center dot(H2O)} (2), and {[Co(Mitz)2(H2O)2]center dot(H2O)} (3) [Mitz = 3-tetrazole-6-methyl-5-(4-pyridyl)-2-pyridone]. All the complexes were characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction analysis, X-ray powder diffraction, and thermogravimetric analysis. X-ray diffraction analyses show that complexes 13 have isomorphous structures. The central metal atoms in these complexes are hexacoordinated and connected by two water molecules, two nitrogen atoms from different tetrazolyl groups, and two oxygen atoms from carbonyl functions respectively. The fluorescent emission spectrum of 1 in the solid-state at room temperature shows a maximal emission peak at 365 nm.