Using an acyclic hexadentate pyridine amide ligand, containing a –OCH2CH2O– spacer between two pyridine-2-carboxamide units (1,4-bis[o-(pyrydine-2-carboxamidophenyl)]-1,4-dioxabutane (H2L9), in its deprotonated form), four new complexes, [CoII(L9)] (1) and its one-electron oxidized counterpart [CoIII(L9)][NO3]·2H2O (2), [NiII(L9)] (3) and [CuII(L9)] (4), have been synthesized. Structural analyses revealed that the CoII centre in 1 and the NiII centre in 3 are six-coordinate, utilizing all the available donor sites and the CuII centre in 4 is effectively five-coordinated (one of the ether O atoms does not participate in coordination). The structural parameters associated with the change in the metal coordination environment have been compared with corresponding complexes of thioether-containing hexadentate ligands. The μeff values at 298 K of 1–4 correspond to S = 3/2, S = 0, S = 1 and S = 1/2, respectively. Absorption spectra for all the complexes have been investigated. EPR spectral properties of the copper(II) complex 4 have been investigated, simulated and analyzed. Cyclic voltammetric experiments in CH2Cl2 reveal quasireversible CoIII–CoII, NiIII–NiII and CuII–CuI redox processes. In going from ether O to thioether S coordination, the effect of the metal coordination environment on the redox potential values of CoIII–CoII (here the effect of spin-state as well), NiIII–NiII and CuII–CuI processes have been systematically analyzed.