Synthesis, Characterization and DFT Studies of Two Zinc(II) Complexes Based on 2-Isopropylimidazole

Abstract

Two novel coordination compounds, [Zn(L)2(OOCH)2] (1) and [Zn(L)3(OCHO)](OCHO)]·H2O (2) (where L = 2-isopropylimidazole, C6H10N2) have been prepared by reaction of 2-isopropylimidazole with zinc(II) formate at room temperature using toluene as solvent. These compounds were characterized by elemental and thermal analyses, IR, 1HNMR and 13CNMR spectroscopies, single crystal X-ray diffraction and DFT studies. The Zn centers in 1 and 2 adopt pseudo-tetrahedral coordination geometries. Compound 1 crystallizes in the monoclinic system P2/c space group whereas compound 2 crystallizes in the P-1 space group of the triclinic crystal system. Several types of hydrogen intra-/intermolecular interactions are observed in these materials and extend into a two-dimensional leaf like network in 1 and a two-dimensional lattice of rectilinear pillars in 2. Compounds 1 and 2 were also optimized and their frontier molecular orbitals, global reactivity descriptors, molecular electrostatic potential, natural bond orbitals were investigated using density functional theory (DFT). In fact the induced structural differences from complex 1 to complex 2 led to the reduction of the frontier molecular orbital energy gap by 1.338 eV and a decrease of the chemical hardness by 0.669 eV.