Cobalt(III) complexes with linear hexadentate N6 or N4S2 donor set atoms providing pyridyl–amide–amine/thioether coordination

Two new cobalt(III) complexes of symmetric hexadentate ligand with N6 [1,10-bis(2-picolinamide)-4,7-diazadecane (pycdpnen)] and N4S2 [1,8-bis(2-picolinamide)-3,6-dithiaoctane (pycdadt)] donor set atoms have been synthesized as perchlorate salts and characterized by spectroscopic methods. All two ligands with strong-field pyridylcarboxamido N donor stabilize Co(III) as demonstrated by the facile oxidation of the cobalt center. The structures of [Co(pycdpnenH−2)](ClO4) (1) and [Co(pycdadtH−2)](ClO4) · H2O (2) investigated by COSY, HMBC, HMQC and NOESY NMR studies show that compounds 1 and 2 have the same geometrical configuration. The X-ray analysis reveals that complex 2 crystallizes in a orthorhombic space group Pccn. The cation [Co(pycdadtH−2)]+ is distorted octahedral with the two pyridyl groups in cis position.