It is shown that the isomorphic substitution of one of the paramagnetic ions of di-homonuclear cluster with antiferromagnetic exchange interaction by an ion, whose wave functions are reversed in time with respect to the wave functions of the substituted ion, leads to the formation of a di-heteronuclear cluster with ferromagnetic exchange interaction. This method of spin rearming can be used for the synthesis of new di-heteronuclear clusters with ferromagnetic exchange interaction. The redox-induced processes can affect the time-reversal symmetry. Particularly in the reduction-half reaction + 2 Cu the time-reversal symmetry for the ion, existing before the start of the reaction, disappears after the reaction due to the transformation of the ion with spin S = 1/2 into a neutral Cu atom without spin. An analogy is found between six incomplete time-reversal operators for systems with spins S = 1/2, 3/2, 2, 5/2.