2,2,6,6-tetramethylpiperidine-1-oxyl in benzene byproducts: 2,2,6,6-tetramethylpiperidine-1-ol; piperidyl-compound was added to a soln. of complex in C6H6 under N2, themixt. was stirred at room temp. for 30 min, an excess of iodine was add ed; column chromy.;