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 prepared and characterized (in most cases crystallographically). These complexes include: tetracoordinate [Ni(L1O)Cl]; pentacoordinate [Ni(L1O)(acac)] and [Ni(L1O)(OAc)]; and hexacoordinate [Ni(L1O)(acac)(pz)], [Ni(L1O)(OAc)(MeOH)], and [Ni(L1O)(2)]. This second generation of heteroscorpionate ligand supports a tetrahedral environment for Ni(II) but is not a tetrahedral enforcer. Thus the tetra- and pentacoordinate species readily add additional ligands to produce 5- and 6-coordinate complexes. The formation of the undesirable, coordinatively saturated, [Ni(L1O)(2)], "sandwich" complex is only a minor interference in most of these reactions unlike the situation seen with the previous generation of ligand. This family of heteroscorpionates shows promise as platforms for biomimetic studies which are already underway.