Sodium-mediated self-assembly of two nickel(II) Schiff base complexes: crystal structure and characterizations

Sodium-assisted self-assembly of two nickel(II) Schiff base complexes under similar reaction conditions yield hetero-metallic compounds [{Ni(salpn)}(2)Na(ClO4)] (1) and [{Ni(salpr)}(3)Na][Ni(salpr)](2)ClO42H2O (2) (where salpn=N,N-bis-(salicylidene)-1,3-diaminopropane and salpr=N,N-bis-(salicylidene)-1,2-diaminopropane). Both have been characterized by physico-chemical techniques and single-crystal X-ray diffraction. Crystal structure reveals that in the tri-metallic system of 1 sodium is sandwiched between two [Ni(salpn)] units while the hexametallic system of 2 consists of tetrametallic cluster ion [{Ni(salpr)}(3)Na](+) with encapsulated sodium by three [Ni(salpr)] units. In both complexes, sodium adopts distorted trigonal prismatic geometry leaving nickel(II) in a distorted square-planar environment. Structural characterization also reveals that 2:1 (for 1) and 3:1 (for 2) self-assemblies of metallo-ligand and sodium were achieved with slight variation in ligand backbone.