Cobalt and copper complexes with formamidine ligands: Synthesis, crystal X-ray study, DFT calculations and cytotoxicity

Abstract

Co(II) and Cu(II) complexes with distorted octahedral and distorted square planar geometries of the type [Co(L2)2(H2O)2](NO3)2 and [Cu(L1)2Cl2] have been prepared and characterized using elemental analysis, IR and crystal X-ray studies. The two complexes were prepared with two novel formamidine ligands, N′-(benzothiazol-2-yl)-N,N-dimethylformamidine (L1) and N-(pyridin-2-yl)formamidine (L2). [Cu(L1)2Cl2] crystallized in the space group P21/c, a = 8.5987(3) Å, b = 15.9778(6) Å, c = 10.6308(7) Å, V = 1321.07(11) Å3, Z = 4. [Co(L2)2(H2O)2](NO3)2 crystallized in the space group P21/c, a = 7.9187(2) Å, b = 10.8117(4) Å, c = 11.6687(5) Å, V = 902.13(6) Å3, Z = 4. The existence of H-bonding in the complex [Co(L2)2(H2O)2](NO3)2 is discussed. The negative values of the electronic energies (−2329.59 to −4461.21 a.u.), the highest occupied molecular orbital energies (−0.2311 to −0.2590 a.u.) and the lowest unoccupied molecular orbital energies (−0.063 to −0.08525 a.u.) of the complexes indicate the stability of the complexes. The complexes have noticeable cytotoxicity with IC50 (µmole/well) values of 0.002 and 0.047 (MCF-7), 0.0048 and 0.051 (HCT-116), 0.0014 and 0.044 (HepG-2) for the copper and cobalt complexes; respectively.