Cuprous and cupric complexes with the new imidazolyl containing tripodal tetradentate ligands {L^MIm, (1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)methanamine, and L^EIm, 2-(1H-imidazol-4-yl)-N,N-bis((pyridin-2-yl)methyl)ethanamine}, have been investigated to probe differences in their chemistry, especially in copper(I)−dioxygen chemistry, compared to that already known for the pyridyl analogue TMPA, tris(2-pyridyl)methyl)amine. Infrared (IR) stretching frequencies obtained from carbon monoxide adducts of [(L^MIm)Cu^I]⁺ (1a) and [(L^EIm)Cu^I]⁺ (2a) show that the imidazolyl donor is stronger than its pyridyl analogue. Electrochemical data suggest differences in the binding constant of Cu^II to L^EIm compared to TMPA and L^MIm, reflecting geometric changes. Oxygenation of [(L^MIm)Cu^I]⁺ (1a) in 2-methyltetrahydrofuran (MeTHF) solvent at −128 °C leads to an intensely purple colored species with a UV−vis spectrum characteristic of an end-on bound peroxodicopper(II) complex [{(L^MIm)Cu^II}₂(μ-1,2-O₂²⁻)]²⁺ (1b^P) {λ_max = 528 nm}, very similar to the previously well characterized complex [{(TMPA)Cu^II}₂(μ-1,2-O₂²⁻)]²⁺ {λ_max = 520 nm (ε = 12 000 M⁻¹ cm⁻¹), in MeTHF; resonance Raman (rR) spectroscopy: ν(O−O) = 832 (Δ(¹⁸O₂) = −44) cm⁻¹}. In the low-temperature oxygenation of 2a, benchtop (−128 °C) and stopped-flow (−90 °C) experiments reveal the formation of an initial superoxo-Cu(II) species [(L^EIm)Cu^II(O₂^•−)]⁺ (2b^S), λ_max = 431 nm in THF) . This converts to the low-temperature stable peroxo complex [{(L^EIm)Cu^II}₂(μ-1,2-O₂²⁻)]²⁺ (2b^P) {rR spectroscopy: ν(O−O) = 822 (Δ(¹⁸O₂) = −46) cm⁻¹}. Complex 2b^P possess distinctly reduced Cu−O and O−O stretching frequencies and a red-shifted UV−vis feature {to λ_max = 535 nm (ε = 11 000 M⁻¹ cm⁻¹)} compared to the TMPA analogue due to a distortion from trigonal bipyramidal (TBP) to a square pyramidal ligand field. This distortion is supported by the structural characterization of related ligand−copper(II) complexes: A stable tetramer cluster complex [(μ₂-L^EIm−)₄(Cu^II)₄]⁴⁺, obtained from thermal decomposition of 2b^P (with formation of H₂O₂), also exhibits a distorted square pyramidal Cu(II) ion geometry as does the copper(II) complex [(L^EIm)Cu^II(CH₃CN)]²⁺ (2c), characterized by X-ray crystallography and solution electron paramagnetic resonance (EPR) spectroscopy.