Theoretical investigation on the structure and electronic properties for three species of (N,N'-bis(salicylidene)-ethylenediamine)zinc

摘要

The geometric and electronic structures of three species of Zn(salen) were investigated using OFT. The results show that the coordination geometries around the zinc ions are distorted tetrahedra whether for the monomer or for the helical, while that of the dimer are distorted bi-pyramidal. The order of their stabilization is the helical>the dimer>the monomer. Their electronic distribution of HOMO and LUMO also exhibits different characteristic. For the monomer, the HOMO is mainly localized in phenoxide ring, whereas its LUMO mostly distributes on azomethine. The HOMO of the dimer is localized on the nonbridging ligands, and the LUMO is localized on the bridging ligands. For the helical, the HOMO is localized on the two parallel phenoxido sides, with no electron distribution on the other two nonparallel phenoxido sides, however, the LUMO is fully delocalized on whole molecule. But then, for all species, the electronic population of HOMO is concentrated on O2, C7, C9 and C5 of phenoxido ring mainly, that of LUMO is concentrated on C4, N3 of azomethine(C=N) mainly. The order of energy band gap is the helical structure