Anion Influence on the Structure of N,O-Hybrid Pyrazole ZnII, CdII, and HgII Complexes. Synthesis, Characterization, and Theoretical Studies

In this paper we describe the synthesis and characterization of three new complexes of the 1,8-bis­(3,5-dimethyl-1H-pyrazol-1-yl)-3,6-dioxaoctane ligand (L) with ZnII (1A), CdII (2A), and HgII (3A) ions. The aim of the present study is to investigate the structural effect of the counteranion (Cl– vs ClO4–) on the type and geometry of the structures of the complexes as well as the ligational behavior of the ligand. Depending on the type of the counteranion, the structural studies revealed a variety of modes of bonding (N,N-bidentate/N,O,O,N-tetradentate), coordination geometries (tetrahedral/octahedral), and different nuclearities (monomer/polymer). Moreover, the density functional theory computational study in combination with several experimental techniques as well as the investigation of the extended structures allowed us to understand the role of the different anions in the structure of the complexes.