Nickel(II) and cobalt(II) complexes with a mixed donor acyclic ligand bearing heterocyclic moieties as terminal groups

New nickel(II) and cobalt(II) complexes of a symmetric acyclic mixed O,N,S-donor ligand, S,S′-bis(8-quinolyl)-4-oxo-1,7-dithiaheptane (OESQ), with quinoline as the terminal group, [M(OESQ)(H₂O)](NO₃)₂ [M = Ni^II (1) and Co^II (2)], have been prepared and characterized by elemental analyses, u.v.-vis, and i.r. spectra, and by magnetic susceptibility measurement. Single X-ray diffraction analyses show that (1) and (2) are isomorphous. The nickel (or cobalt) ion in (1) [or (2)] is hexa-coordinated and the complex cation exhibits a slightly distorted-octahedral geometry defined by all five donor atoms of the ON₂S₂ of OESQ and a water, molecule with N₂S₂ in equatorial and two oxygens in axial position.