First-Row Transition-Metal Complexes of a New Pentadentate Ligand, α,α,α′,α′-Tetra(pyrazolyl)lutidine

A new pentadentate ligand, α,α,α′,α′-tetra(pyrazolyl)lutidine, pz₄lut, has been prepared by a CoCl₂-catalyzed rearrangement reaction between 2,6-pyridinedicarboxaldehyde and dipyrazolylthione. The coordination chemistry with some divalent first-row transition metal (Mn, Fe, Co, Ni, Cu, and Zn) chlorides has been explored. The electronic properties indicate that the new κ⁵N ligand is a slightly stronger-field donor to Ni²⁺ and Co²⁺ than a related pentadentate ligand with five pyridyl donors presumably because of greater interaction between the metal and axial pyridyl.