Structures and Magnetic Properties of Monomeric Copper(II) Bromide Complexes with a Pyridine-Containing Tridentate Schiff Base

Abstract

Two novel copper(II) bromide complexes with pyridine containing Schiff base ligands, Cu(pmed)Br 2 and Cu(dpmed)Br 2 where pmed = N'-((pyridin-2-yl)methylene)ethane-1,2-diamine (pmed) and dpmed = N,Ndiethyl-N'-((pyridin-2-yl)methylene)ethane-1,2-diamine (dpmed) were synthesized and characterized using Xray single crystal structure analysis, optical and magnetic susceptibility measurements. Crystal structural analysis of Cu(pmed)Br 2 showed that the copper(II) ion has a distorted square-pyramidal geometry with the trigonality index of τ = 0.35 and two intermolecular hydrogen bonds, which result in the formation of two dimensional networks in the ab plane. On the other hand, Cu(dpmed)Br 2 displayed a near square-pyramidal geometry with the value of τ = 0.06. In both compounds, the NNN Schiff base and one Br atom occupy the basal plane, whereas the fifth apical position is occupied by the other Br atom at a greater Cu-Br apical distance. The reported complexes show g ⎟⎜ > g ⊥ > 2.0023 with a d x 2 -y 2 ground state and a penta-coordinated square pyramidal geometry. Variable temperature magnetic susceptibility measurements showed that the developed copper(II) complexes follow the Curie-Weiss law, that is there are no magnetic interactions between the copper(II) ions since the Cu--Cu distance is too far for magnetic contact.

Halide Copper(ii) Complexes of Aromatic N-Donor Containing Ligands: Structural, Magnetic and Reactivity Studies

“…In compound 1 (Fig. 1, a) this square-planar configuration is formed by Cu-N(pyridine) and Cu-Br bonds of 1.9805(18) Å and 2.4052(4) Å, respectively, the bromide and nitrogen atoms adopting a trans configuration similar to other related structures [30][31][32][33][34][35][36][37]. This configuration is preferred since the 2-benzylpyridine is a bulky ligand and in this way the steric repulsion is minimized.…”

“…Cu(II) atom has five fold coordination giving a quasi-square pyramidal configuration with W = 0.29 [ 38 ]. The base of the square pyramid is defined by the N atoms of the bpy and 2-benzylpyridine (2.036(3) Å being average Cu-N distance) and the bromide atom closest to Cu(II) center (2.4381(6) Å), while the [ 33 ]. The structure has a five-membered chelate ring which gives a greater stability to this complex as compared to 1 and 3.…”