Multiple coordination modes of a new ditopic bis(pyrazolyl)methane-based ligand

Abstract

A new ditopic ligand, N-(2,2-bis(pyrazolyl)ethyl)-2,2-bis(pyrazolyl)acetamide ((pz)₂CH–C(O)–NH–CH₂–CH(pz)₂, L4Pz, pz = pyrazolyl ring), comprising two bis(pyrazolyl)methane donor groups linked via an amide bridge, has been prepared from the reaction of HOOCCH(pz)₂ and H₂NCH₂CH(pz)₂. The ligand coordinates to various metallic salts (i.e. AgO₃SCF₃, PdCl₂, Re(CO)₅Br, and Fe(BF₄)₂), in either a κ²–μ–κ² or a κ³–μ–κ² fashion, depending on the coordination preferences of the metallic center. These compounds were characterized by NMR, UV-Vis and IR spectroscopy, and in solid state by single crystal X-ray diffraction. In the case of silver(I), a mono-dimensional coordination polymer was obtained, while the others were found to be discrete complexes. The synthesis and characterization of a heterobimetallic complex is also described. In solid state, all compounds are associated into supramolecular architectures via hydrogen bonding and pyrazolyl embrace interactions.