The MRI contrast agents (CAs) have been routinely used for detecting tumors at early stages. Currently, the most used CAs in MRI are gadolinium (Gd3+) complexes. However, these CAs can be toxic to the body. Thus, this work proposes Ni2+ complexes ([Ni(ACAC)2(H2O)2], [Ni(TEA)]2+) as promising CAs. For the theoretical prediction, molecular dynamics simulations were carried out and the conformations were selected by the optimal wavelet signal compression algorithm method. The T1 and T2 values were obtained directly by means of the spectral density. Our findings showed that the Ni2+ complexes can be promising CAs in MRI.