A metal-directed pyrazoline–1,5-diazapentadiene rearrangement of a novel [2 + 2] macrocycle: crystal and molecular structures of L3 and [Ni2(L2)]·5H2O

Abstract

The condensation of pentane-2,4-dione with pyridine-2,6-dicarbohydrazide leads to a structurally characterised [2 + 2] macrocyclic product containing two pyrazoline rings; reaction with transition metal ions leads to binuclear complexes of which the dinickel(II) complex has been structurally characterised and shown to contain two square-planar nickel ions co-ordinated to ring-opened pyrazoline groups.