Dinuclear CuII and NiII complexes of 3-formylsalicylic acid oxime:: cis/trans topology and extension of a cis-CuII2 complex to a pentanuclear CuIICuIIMnIICuIICuII complex

3-Formylsalicylic acid oxime (H3L) formed the following dinuclear Cu-II and Ni-II complexes: [Cu-2 (HL)(2)].0.5H(2)O (1), Na[Cu-2 (HL)(L)] . 3H(2)O (2) and [Ni-2 (HL)(2)].2.5H(2)O (3). The structures of Na[Cu-2 (HL)(L)(H2O)] (2') and [Ni-2 (HL)(2) (H2O)(4)]. 8H(2)O (3') have been determined by X-ray crystallography. Complex 2 has a cis arrangement of the two ligands providing dissimilar {CuN2O2} and {CuO4} chromophores sharing the two phenolic oxygen atoms. The N2O2 cavity has a hydrogen-bonded N-O . . .H . . .O-N linkage as the lateral chain, and the Cu in this site has a square-pyramidal geometry with a water molecule at the axial site. The Cu in the O-4 cavity has a planar geometry. Complex 3 has a trans configuration with respect to its two ligands and each Ni has a six-coordinate geometry with two water molecules at the axial sites. Complex 1 has a trans configuration based on its having a chemical formula and IR spectrum similar to 3. The following interconversion among dinuclear Cu complexes has been established by pH adjustment: trans-[Cu-2 (HL)(2)] (1) reversible arrow cis-[Cu-2 (HL)(L)](-) (2) reversible arrow trans-[Cu-2 (L)(2)](2-) (water molecules are omitted). On the other hand, 3 showed the following interconversion: trans-[Ni-2 (HL)(2)] (3) reversible arrow trans-[Ni-2 (L)(2)](2-). The cis Cu2 complex 2 was reacted with Mn-II to afford [Mn{Cu-2 (HL)(L)}(2) (H2O)(4)].H2O . 2DMF (4) that has a linear pentanuclear Cu-II Cu-II Mn-II Cu-II Cu-II structure formed by the coordination of two molecules of 2 to a Mn-II through a carboxylate group.