Biological systems exhibit state-of-the-art control over reactivity through the choice of metal ions, ligand environments, and redox properties in many fundamental aspects of coordination chemistry. The diversity offered by biological coordination complexes/chemistry has inspired chemists, amongst others, to design and develop a multitude of small molecule bio-mimetics for various applications to manipulate biological processes. Unsymmetrical N-aryl-N′-alkylpyridyl β-diketiminato copper(I) complexes, synthesized to enhance stability and explore new binding motifs, exhibit reversible CO binding and resistance to disproportionation. The CO binding affinity and pyridyl ligand de-coordination rate depend on the interplay between chelate puckering and steric effects of the N-aryl substituent. Investigating O2 reactivity revealed that the length of the chelating pyridyl arm (methyl vs. ethyl) dictates the formation of mono- or di-nuclear copper-dioxygen species. The pyridylmethyl ligation copper(I) complex undergoes ligand degradation, while the pyridylethyl ligation copper(I) complex forms a stable dinuclear species. Further studies of β-diketiminato copper(II) complexes and their nitrite adducts showed that the pyridyl arm length influences the Cu(II)/Cu(I) redox potential and the geometry of the complexes, as confirmed by X-ray crystallography, cyclic voltammetry, DFT, and EPR analyses. Oxygen atom transfer (OAT) nitrite reduction yields copper(I)–PPh3 and OPPh3, with the NO-releasing ability governed by the pyridyl arm length. DFT calculations revealed a two-PPh₃-assisted OAT mechanism with a ΔG‡ of 34.8 kcal mol⁻¹, consistent with experimental data and product yields. Furthermore, β-thioketiminate ligands (SN and SNN chelators) form copper(I) complexes with varying nuclearity and coordination modes, influenced by the pendant pyridyl arm length. Ligand modifications with electron-withdrawing/donating groups or varied N-aryl/backbone substituents yield trimers with tunable intramolecular Cu⋯Cu interactions (cuprophilicity), primarily determined by N-aryl steric bulk, as confirmed by X-ray crystallography and Raman spectroscopy. These results highlight the significant impact of ligand design on the stability, reactivity, and binding properties of copper complexes, underscoring their potential for bioinspired catalysis and diverse applications.