Two complexes {[Co^II(phen)₃][Co^III(phen)(CN)₄]₂}·phen·11H₂O (1) and [Co^II(μ-CN)₂(Co^III)₂(phen)₄(CN)₆]·C₂H₅OH·2H₂O (2) were synthesized with identical starting materials but with a different order of addition. Their crystal structures, spectroscopic analysis, DFT calculations, and investigations of their magnetic properties are reported herein. The X-ray diffraction studies reveal that complex 1 mainly consists of discrete [Co^II(phen)₃]²⁺ cations and [Co^III(phen)(CN)₄]⁻ anions, while complex 2 is dominantly comprised of discrete neutral V-shaped trinuclear units [Co^II(μ-CN)₂(Co^III)₂(phen)₄(CN)₆]. The first low-spin Co^II fragment with homoleptic 1,10-phenanthroline ligands in 1 is observed at room temperature, owing to charge transfer from the neighboring anion via adventitious contacts and anion–π interactions. This is verified by structures, detailed theoretical analyses concerning frontier molecular orbital energy differences and Mulliken charge variations of the N atoms within the Co^IIN₆ sphere, and magnetism. Meanwhile, these kinds of supramolecular interactions are not found in complex 2, so it shows the ordinary magnetic behavior of the high-spin Co^II ion. Our investigations highlight that for quantitative comprehension of spin-state energetic ordering in transition metal complexes, the supramolecular interactions must be taken into account in addition to classical ligand field theory. Moreover, we find that the [Co^II(phen)₃]²⁺ dication is sensitive to its surroundings in the solid state, which is beneficial for magnetic adjustment for the further synthesis of tunable molecular magnets and spin crossover systems.