This study focuses on the quantum magnetic properties and entanglement of trinuclear C84H75N12Ni3O3 · 3(ClO4) · 6.5(C3H7NO) and tetranuclear C24H54Cl2N10Ni4O19. This study compares experimental data with exact theoretical calculations of magnetic susceptibility as a function of temperature, revealing excellent agreement. We observe a correlation between magnetization jumps, magnetic susceptibility peaks, and logarithmic negativity plateaus, in response to changes in external magnetic fields for trinuclear and tetranuclear Ni ion complexes at low temperatures. These observations require further experimental measurements in external magnetic fields at low temperatures.