Synthesis and crystal structures of cobalt(III) complexes containing pyridine-2-selenolato and its oxidation products

Abstract A series of mixed cobalt(III) complexes [Co(pySe) 3− n (NN) n ] n + [pySe=pyridine-2-selenolato (1−); NN=1,2-ethanediamine (en) and 2,2′-bipyridine (bpy); n =0, 1 and 2] was prepared. The geometrical preference and trans influence of pySe are fairly different from those of pyridine-2-thiolate. These selenolato complexes were oxidized by peracetic acid to give the corresponding pyridine-2-seleninato (pySeO 2 ) and pyridine-2-selenonato (pySeO 3 ) complexes. The crystal structures of the pySeO 2 and pySeO 3 complexes revealed that the coordination mode change from an original N , Se -four-membered to the N , O -five-membered chelate ring occurred during oxidation and intramolecular hydrogen bonds between the non-coordinated oxygen of pySeO 2 or pySeO 3 and the amine protons of en stabilize the N , O -coordination mode.