Halido-Bridged Dinuclear Nickel and Zinc Complexes with a Bis(tripodal) Octaamine Ligand - Unusual Coordination Mode of an ortho-Phenylenediamine

摘要

A potentially dinucleating octaamine ligand H-6-4 consisting of two aliphatic tripodal tetraamine units connected by all ortho-phenylenedramine spacer has beets synthesized. Treatment of H-6-4 with Ni(BF4)(2)center dot 6H(2)O or H-10-4(BF4)(4) with Et2Zn in the presence of a halide source leads to the formation of the dinuclear complexes [Ni-2(mu-Cl)(2)(H-6-4)](BF4)(2) (5) and [Zn(mu-F)(H-6-4)](BF4)(3) (6), respectively, which were Structurally characterized by X-ray diffraction studies. In both 5 and 6 the ligand coordinates with four nitrogen donors to each metal center The ortho-phenylenediamine bridging unit coordinates in an unprecedented fashion with each of its amine functions to only one of the metal centers The dinickel complex 5 possesses two bridging chlorido ligands that differ notably in their Cl-Ni bond lengths, due to interactions of four amine N-H protons with one of the chlorido bridges leading to a reduced donor ability. The dizinc complex 6 was synthesized without addition of all external halide source The two zinc atoms in 6 facilitate the abstraction of a fluoride from a tetrafluoroborate anion through a cooperative activation by the two adjacent metal centers.