Mononuclear Ni(II) complexes can be designed to behave as two-level systems and thus play the role of qbits with eventually large coherence time. The objective of this proposal is to evaluate accurately the spin Hamiltonian parameters of two Ni(II) complexes that possess the same geometry but slightly differ by some structural parameters using INS measurements. This will enable us to link the degree of distortion to the nature of the two-level system and then eventually to their coherence time.