Synthesis, characterization and crystal structure of dinuclear cobalt(II) macrocyclic complexes, containing thiocyanate and azide groups

Abstract

Dinuclear cobalt(II) complexes with II–II oxidation state of 20-membered N4, binucleating macrocycle derived by a cyclic [2+2] condensation of isophthaldialdehyde with 1,3-diaminopropane have been synthesised and characterised by analytical, spectroscopic and X-ray diffraction methods. The solid and solution states investigations show that overall structures and geometries of the complexes are very similar. The molecular structure of [Co2L(OMe)(NCS)3], which has been determined by single crystal X-ray diffraction, indicate that the cobalt(II) ions have a distorted trigonal bipyramidal environment, with methoxy bridge in an equatorial positions and N-bound thiocyanate ion in axial positions to metals. Also, the structure of [Co2L(OMe)(NCS)3] complex was optimized using density functional theory for all of the possible spin states of the complex. The results indicated that septet spin state is the most stable form of the complex.