Structure and magnetic properties of 3-oxyl-4,4,5,5-tetramethyl-2-oxoimidazolidin-1-olates

The paramagnetic salts (NH3But)1 and [K(NH2But)2]1, where 1 is the 3-oxyl-4,4,5,5-tetramethyl-2-oxoimidazolidin-1-olate anion, were isolated. The crystal structure of [K(NH2But)2]1 involves polymer chains formed by hydrogen bonding between anions 1 and [K2(NH2But)4]2+ cation dimer fragments. The magnetic properties of [K(NH2But)2]1 are well described by the quasi-isolated dimer model with spins S = 1/2 coupled by weak exchange interactions via [K2(NH2But)4]2 fragments in polymer chains.