Pyridone derivatives carrying radical moieties: Hydrogen-bonded structures, magnetic properties, and metal coordination

Pyridone derivatives carrying radical moieties were prepared, namely a nitronyl nitroxide derivative 5-(4′,4′,5′,5′-tetramethylimidazoline-3′-oxide-1′-oxyl)-2(1H)-pyridone (1) and a verdazyl derivative 1,5-dimethyl-3-[2(1H)-pyridone]-6-oxoverdazyl (2). In the solid state, 1 and 2 form, via N–H⋯O intermolecular hydrogen bonds between the pyridone moieties, a zigzag one-dimensional chain structure and a cyclic dimer structure, respectively. These compounds exhibit antiferromagnetic intermolecular interactions. Mononuclear metal complexes [M(hfac)2(1)2] (M = CuII, MnII; hfac = bis(hexafluoroacetylacetonate)) were prepared in which trans-[M(hfac)2] are coordinated with the carbonyl oxygen of the pyridone ligands. Cyclic hydrogen bonds between the mononuclear units result in the formation of one-dimensional chains. Small antiferromagnetic (for CuII) and ferromagnetic (for MnII) exchange interactions between the metal ion and the ligands were observed.

Graphical abstractPyridone derivatives carrying radical moieties were prepared, namely a nitronyl nitroxide derivative 5-(4′,4′,5′,5′-tetramethylimidazoline-3′-oxide-1′-oxyl)-2(1H)-pyridone (1) and a verdazyl derivative 1,5-dimethyl-3-[2(1H)-pyridone]-6-oxoverdazyl (2). The radicals formed hydrogen-bonded structures in the solid state. Mononuclear metal complexes [M(hfac)2(1)2] (M = CuII, MnII) were prepared, and their crystal structures and magnetic properties were investigated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pyridone derivatives carrying nitronyl nitroxide and verdazyl moieties were prepared. ► The radicals formed hydrogen-bonded structures in the solid state. ► Mononuclear complexes of [M(hfac)2] with two radical ligands were formed.