Reaction of cobalt(II) chloride hexahydrate with N‐substituted diethanolamines H2L2–4 (3) in the presence of LiH in anhydrous THF leads under anaerobic conditions to the formation of three isostructural tetranuclear cobalt(II) complexes CoII4(Cl)4(HL2–4)4 (4) with a Co4(μ3‐O)44+ cubane core. According to X‐ray structural analyses, the complexes 4 a,c crystallize in the tetragonal space group I41/a, whereas for complex 4 b the tetragonal space group P$\bar 4$ was found. In the solid state the orientation of the cubane cores and the formation of a 3D framework were controlled by the ligand substituents of the cobalt(II) cubanes 4. This also allowed detailed magnetic investigations on single crystals. The analysis of the SQUID magnetic susceptibility data for 4 a gave intramolecular ferromagnetic couplings of the cobalt(II) ions (J1≈20.4 K, J2≈7.6 K), resulting in an S=6 ground‐state multiplet. The anisotropy was found to be of the easy‐axis type (D=−1.55 K) with a resulting anisotropy barrier of Δ≈55.8 K. Two‐dimensional electron‐gas (2DEG) Hall magnetization measurements revealed that complex 4 a is a single‐molecule magnet and shows hysteretic magnetization characteristics with typical temperature and sweep‐rate dependencies below a blocking temperature of about 4.4 K. The hysteresis loops collapse at zero field owing to fast quantum tunneling of the magnetization (QTM). The structural and electronic properties of cobalt(II) cubane 4 a, deposited on a highly oriented pyrolytic graphite (HOPG) surface, were investigated by means of STM and current imaging tunneling spectroscopy (CITS) at RT and standard atmospheric pressure. In CITS measurements the rather large contrast found at the expected locations of the metal centers of the molecules indicated the presence of a strongly localized LUMO. Inversion of magnetoanisotropy: The novel tetranuclear CoII cubane CoII4(Cl)4(HL2)4 shown in the figure (R=nBu) was synthesized from N‐substituted diethanolamine H2L2, LiH, and CoII ions (D>0 K). It exhibits an easy‐axis type of single‐molecule magnet behavior with an energy barrier of Δ≈55.8 K (D=−1.55 K), which is comparable to that of {Mn12}, and a blocking temperature of 4.4 K, but the hysteresis loops are collapsed owing to fast zero‐field relaxation.