Species 1-6 are [M-III(L)(2)]ClO4 complexes formed with the PhO-_CH=N-CH2-PY imines, (L-I)- and (L-tBul)-, and PhO-_CH2-NH-CH2-Py amines, (L-A) - and (L-tBuA) -, in which PhO- is a phenolate ring and Py is a pyridine ring and the prefix tBu indicates the presence of tertiary butyl groups occupying the positions 4 and 6 of the phenol ring. Monometallic species with d(5) high-spin iron (1, 2, 3, 4) and d(10) gallium (5, 6) were synthesized and characterized to assess the influence of the ligand rigidity and the presence of tertiary butyl-substituted phenol rings on their steric, electronic, and redox behavior. Characterization by elemental analysis, mass spectrometry, IR, UV-visible, and EPR spectroscopies, and electrochemistry has been performed, and complexes [Fe-III(L-tBul)(2)]ClO4 (2), [Fe-III (L-tBuA)ClO4 (4), and [Ga-III(L-tBul)(2)]ClO4 (5) have been characterized by X-ray crystallography. The crystal structures show the imine ligands meridionally coordinated to the metal centers, whereas the amine ligands are coordinate in a facial mode. Cyclic voltammetry shows that the complexes with the ligands (L(tBu)l)(-) and (L-tBuA)(-) were able to generate ligand-based phenoxyl radicals, whereas unsubstituted ligands displayed ill-defined redox processes. EPR spectroscopy supports high-spin configurations for the iron complexes. UV-visible spectra are dominated by charge-transfer phenomena, and imine compounds exhibit dramatic hyperchromism when compared to equivalent amines. The tertiary butyl groups on the phenolate ring enhance this trend. Detailed B3LYP/6-31G(d)-level calculations have been used to account for the results observed.