Heteroleptic Binuclear Pivalate-, Pyrazolate-Bridged Copper(II) Complexes with 1,10-Phenanthroline

The reaction of the mononuclear complex [PhenCu(OOC^tBu)₂(H₂O)] (I) with [PhenCu(CH₃CN)(Otf)₂] (Phen = 1,10-phenanthroline, Otf = CF₃S\({\text{O}}_{3}^{ - }\)) in dichloromethane at room temperature gave the binuclear complex [Phen₂Cu₂(µ-OOC^tBu)₂(Otf)₂] (II). The reaction of II with pyrazole (PzH) involved the displacement of the triflate anions to the outer sphere and gave the ionic complex [Phen₂Cu₂(µ-OOC^tBu)₂(PzH)₂](Otf)₂ (III), while a similar reaction with 3,5-bis(trifluoromethyl)pyrazole ((CF₃)₂PzH) was accompanied by its deprotonation and gave the heteroleptic complex [Phen₂Cu₂(µ-OOC^tBu)(µ-(CF₃)₂Pz)(µ-Otf)]Otf (IV). Compounds I–IV were characterized by X-ray diffraction (CCDC nos. 2332399 (I), 2332400 (II), 2332402 (III), and 2332401 (IV)), IR spectroscopy, and elemental analysis. According to X-ray diffraction data, the copper atoms in I–IV occur in a square pyramidal environment. The crystal packing of complexes I–III involves stacking interactions between phenanthroline molecules giving rise to supramolecular chains.