Structural diversity, spectral characterization and computational studies of Cu(I) complexes with pyridylamide ligands

Abstract

Cu(I) complexes supported by pyridylamide ligands N-2-acetamidopyridine (Haap), N-(3-pyridyl)nicotinamide (3-pna), N-(2-pyridyl)isonicotinamide (2-pina) and N-(4-pyridyl)picolinamide (4-ppa) were synthesized and characterized. The reaction of CuCl with the deprotonated form of Haap yielded the complex [Cu2(aap)2]n (1) with a one-dimensional polymeric structure. Complexes [Cu(3-pna)3(NCCH3)](HF)(SbF6) (2) and [Cu(4-ppa)(NCCH3)2]BF4 (5) displayed mononuclear structures with tetrahedral geometries on Cu(I) centers. Dinuclear complex [Cu2(2-pina)3(NCCH3)4](SbF6)2 (3) and tetranuclear cluster [Cu4(2-pina)4(NCCH3)4](SbF6)4 (4) were afforded from the same reaction in CH3CN and DMF, respectively. Detailed analysis of X-ray crystal structures and Hirshfeld surface maps suggested that the weak non-covalent interactions and reaction solvents imposed a collaborative effect on the structural conformations of the Cu(I) complexes. The electrochemical properties of the complexes were investigated by cyclic voltammetry. Computational studies focusing on complex 1 revealed its unique electronic structure that corresponds to the interesting spectroscopic and electrochemical properties.