PUB - Publikationen an der Universität Bielefeld

The new triplesalophen ligand H(6)kruse(Br) was synthesized as a variation of the triplesalophen ligands H(6)baron(R) by replacing a phenyl by a methyl group at the terminal ketimine in order to allow closer contacts of trinuclear complexes due to less steric hindrance by the smaller methyl group. The ligand H(6)kruse(Br) was used to synthesize the trinuclear complex [(kruse(Br)) Ni-3(II)], which is insoluble in organic solvents despite the coordinating solvent pyridine. Recrystallization from pyridine results in the complex [(kruse(Br)){Ni-2(Ni(py)(2))}], which was characterized by single-crystal X-ray diffraction. Two Ni-II ions are four-coordinate by the salophen-like subunits while the third Ni-II ion is six-coordinate by two additional pyridine donors. The analysis of the molecular and crystal structure in comparison to that of Ni-3(II) complexes of (baron(R))(6-) reveals that the methyl group in [(kruse(Br)){Ni-2(Ni(py)(2))}] results in less ligand folding and in closer contact distance of two Ni-3(II) complexes by pi-pi interactions of 3.2 angstrom. This indicates that trinuclear complexes of H(6)kruse(Br) are more suitable than complexes of H(6)baron(R) as molecular building blocks for the anticipated synthesis of nonanuclear single-molecule magnets.