A New phenoxido/trifluoroacetato bridged heterometallic NiII2CuII derivative: Structure, EPR interpretation and DFT computation

The trinuclear heterometallic Ni2II−CuII complex, [Ni2(L)2(CF3COO)2Cu] (1) is afforded incorporating a tetradentate Schiff base precursor, H2L [where H2L = N,N′-bis(salicylidene)-1,3-propanediamine]. In 1, the two terminal NiII atoms are linked to the central CuII by a syn-anti bridging trifluroacetate and a double phenoxido bridge, giving rise to a linear structure. The EPR spectra show that the trinuclear structure remains unchanged in non-coordinating solvents, whereas in DMF and DMSO the resonances of mononuclear CuII species with an axial symmetry and a well-resolved hyperfine structure are observed. DFT calculations reveal that the spin Hamiltonian parameters are gz 2.22 and Az 176.4 × 10−4 cm−1, which are in good agreement with the experimental values. The biological outcome of complex 1 on the viability of different human carcinoma cells are analyzed by MTT assay and the results suggest that it induces a decrease in cell-population growth with apoptosis.