Crystal structure and magnetic properties of two nitronyl nitroxide biradicals and of their copper(II) complexes

The crystal structures and the magnetic properties of two nitronyl nitroxide biradicals, NITPh(4-NIT)=1,4-bis(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-dihydro-1H-3-imidazol-2'-yl)benzene (I) and NITPh(3-NIT)=1,3-bis(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-dihydro-1H-imidazol-2-yl)benzene (II), and of two novel adducts with Cu(hfac) 2 , [Cu(hfac) 2 ] 4 NITPh(4-NIT) (III) and [Cu(hfac) 2 ] 3 NITPh(3-NIT) (IV), where hfac=hexafluoroacetylacetonate, are reported