Syntheses and crystal structures of two novel linear trinuclear Schiff base nickel(II) and cadmium(II) complexes

Two novel linear trinuclear Schiff base complexes, [Ni{Ni(C17H14Br2N2O2)(NO3)(H2O)}(2)].2MeOH.2H(2)O (1), and [Cd{Ni(C25H20N2O2)(CH3COO)}(2)] (2), were synthesized and characterized by elemental analyses, infrared spectroscopy, and X-ray single crystal determinations. There are three bridges across the Ni-M atom pairs (M is Ni for 1, and Cd for 2) in each complex, involving two phenolate O atoms of a Schiff base ligand (N,N'-bis(5-bromosalicylidene)-1,3-propanediaminate (BSPD) for I and N,N'-bis(2-hydroxynaphthylmethenylimino)-1,3-propanediaminate (HNPD) for 2), and an O-N-O moiety of a mu-nitrato group for I or an O-C-O moiety of a mu-acetato group for 2. In each of the complexes, the central M2+ is located on an inversion center and has an octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and one O atom from each bridging nitrate or acetate group in the axial positions. The coordination around the terminal Ni2+ ions is also octahedral for 1, but square pyramidal for 2. The nitrate or acetate bridges linking the central and terminal metal ions are mutually trans. The Ni...M distances are 3.006(2) angstrom in 1, and 3.175(2) angstrom in 2.