A new approach to synthesis of α-nitronyl nitroxide carboxylates. First metal complexes with α-imino nitroxide carboxylate

An effective procedure has been developed for the synthesis of the potassium salt of 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl-3-oxide-2-carboxylic acid K(1). The salts of 4,4,5,5-tetramethyl-1-oxyl-4,5-dihydro-1H-imidazole-2-carboxylic acid X(2) are kinetically much more stable than K(1). Due to this, a series of heterospin complexes Cu(2)2(CH3OH)2, Cu(2)2(H2O)2, Cu(2)2, Co(2)2(CH3OH)2, Ni(2)2(H2O)2, Ni(2)2(py)2, and Ni(2)2(dipy) · H2O were isolated. For K(2), Cu(2)2(CH3OH)2, and Ni(2)2(py)2, crystal and molecular structure has been determined. For Cu(2)2 and Ni(2)2(bipy), cooperative magnetic ordering has been recorded at 16.6 and 4.6 K, respectively.

Graphical abstractα-Nitronyl- (1) and α-imino nitroxide carboxylates (2) were prepared by hydrolysis of the corresponding nitriles. A series of heterospin complexes with 2 were synthesized. For K(2), Cu(2)2(CH3OH)2, and Ni(2)2(py)2, crystal and molecular structure has been determined. For Cu(2)2 and Ni(2)2(bipy), cooperative magnetic ordering has been recorded at 16.6 and 4.6 K, respectively.Figure optionsDownload full-size imageDownload as PowerPoint slide