In this article, we propose molecular implementation of the quantum logic gate originally realized by the linear triple-quantum dot array accommodating two electrons. To reach this goal we propose to employ the mixed-valence triferrocenium complex exhibiting three isomeric forms with different oxidation degrees FeIII-FeII-FeIII, FeIII-FeIII-FeII, and FeII-FeIII-FeIII, which correspond to three instant localizations of the two holes over three iron ions. The long-range interaction between the terminal metal sites is considered in the framework of the Hubbard-like Hamiltonian which accounts for the electron transfer and inter- and intrasite Coulomb repulsion and takes into account differences in the orbital energies of FeIII and FeII ions. The interaction of the electrons with the applied electric field is also included in the Hamiltonian. It is shown that due to long-range superexchange between the two electronic spins the ground state of the triferrocenium complex is always a spin-singlet, and the first excited level is a spin-triplet. The electric field is shown to increase the antiferromagnetic exchange coupling. The efficiency of the electric field control is especially pronounced due to the field-induced transformation of the system from the isomeric form FeIII-FeII-FeIII to the form FeIII-FeIII-FeII. Estimations of the efficiency of the electric field control of the exchange coupling and entanglement show that the triferrocenium complex is emerging as a potential candidate to act as a gate in quantum computing.