The synthesis and characterization of 4, 5, and 6 coordinate Ni(II) complexes of the "heteroscorpionate'' ligand (3-tert-butyl-2-hydroxy-5-methylphenyl)bis(3,5-dimethylpyrazolyl)methane

Six new Ni(II) complexes of the "heteroscorpionate" ligand (3-tert-butyl-2- hydroxy-5-methylphenyl)bis(3,5-dimethylpyrazolyl)methane, L1OH, have been p repared and characterized (in most cases crystallographically). These compl exes include: tetracoordinate [Ni(L1O)Cl]; pentacoordinate [Ni(L1O)(acac)] and [Ni(L1O)(OAc)]; and hexacoordinate [Ni(L1O)(acac)(pz)], [Ni(L1O)(OAc)(M eOH)], and [Ni(L1O)(2)]. This second generation of heteroscorpionate ligand supports a tetrahedral environment for Ni(II) but is not a tetrahedral enf orcer. Thus the tetra- and pentacoordinate species readily add additional l igands to produce 5- and 6-coordinate complexes. The formation of the undes irable, coordinatively saturated, [Ni(L1O)(2)], "sandwich" complex is only a minor interference in most of these reactions unlike the situation seen w ith the previous generation of ligand. This family of heteroscorpionates sh ows promise as platforms for biomimetic studies which are already underway.