The first stereochemically nonrigid monomeric two-coordinate copper(i) complexes with homoleptic and heteroleptic "n2" donor set

A novel set of stereochemically nonrigid monomeric two-coordinate copper(i) complexes, [Cu(η¹-H₂CPz″₂) ₂]ClO₄1, [Cu(HPz″)₂]ClO₄2, and [Cu(HPz″)(η¹-H₂CPz″₂)]ClO ₄3, where Pz″ = 3,5-di-tert-butylpyrazolyl, has been synthesized and characterized by X-ray diffraction and variable-temperature ¹H NMR spectroscopy. Based on the ¹H NMR line shape analysis of complexes 1 and 2, the intramolecular fluxional process was proposed for these two-coordinate copper(i) complexes. Also, the mixed ligand complex 3 shows that these two different dynamic binding modes of the coordinated HPz″ and H₂CPz″₂ ligands can proceed simultaneously on a single copper(i) ion.