Structure-Function Relationships in the Interaction of Zinc(II) and Cadmium(II) with an Extended Range of 16- to 19-Membered Macrocycles Incorporating Oxygen, Nitrogen, and Sulfur Donor Atoms

Abstract

The interaction of zinc(II) and cadmium(II) with a series of potentially quinquedentate macrocycles incorporating nitrogen, oxygen, and/or sulfur donor atoms is reported. These ligands form part of an extended array in which a systematic variation in donor atom pattern and ring size is present (and against which structure-function relationships are more clearly seen). Stability constants for the 1:1 (metal:ligand) complexes have been determined in 95% methanol (l=0.1 M, NEt 4 ClO 4 ) at 25 o C. The factors influencing the stabilities of individual zinc(II) and cadmium(II) complexes are discussed in the light of a range of crystallographic and other data. The X-ray structures of five complexes, isolated during the study, are reported