Deep insights into novel hexa-coordinated phenoxy-bridged trinuclear Ni(II) asymmetric salamo-like complexes affected by different types of combined solvents

Abstract

By changing different types of combined solvents, two novel trinuclear Ni(II) complexes, [Ni3(L)2(NO3)2(MeOH)2] (1) and [Ni3(L)2(NO3)2]2 (2) were constructed from an asymmetric salamo-type ligand H2L and Ni(NO3)2·6H2O, respectively. The specific coordination modes of the two complexes have been clearly confirmed by X-ray single-crystal data. The results manifested that the complexes 1 and 2 possess similar coordination structures with solvent methanol molecules involved in coordination in complex 1, however, no coordinated solvent molecule appears in complex 2. The ligand (L)2− units were shown to be involved in coordination with Ni(II) atoms by analysis of infrared and UV–vis absorption spectroscopy. DFT and Hirshfeld surfaces analyses were performed on the complexes. Fluorescent strengths of both complexes were markedly lower compared to the ligand H2L and decreased gradually with increasing concentration of Ni(II) ions, which indicated the charge transfer from H2L to Ni(II) ions involved in the coordination.