Mixed ligand helicates and mesocates

Abstract

A 1 : 1 mixture of the homoleptic double helicates [M^II(L¹)₂] and [M^II(L²)₂] [M = Cu, Zn; (L¹)²⁻ and (L²)²⁻ are bis-bidentate ligands containing two pyrazolyl-phenolate termini but with different spacers separating them] affords the mixed ligand complexes [M(L¹)(L²)] in high yield, indicative of a favourable inter-ligand interaction in the mixed-ligand complexes. Whereas [Cu(L¹)(L²)] is a double helicate, [Zn(L¹)(L²)] is a mesocate with a ‘face to face’ arrangement of the two ligands.