Synthesis, structure, and magnetic properties of dinuclear nickel(II) complexes with a phenol-based dinucleating ligand with four methoxyethyl chelating arms

Dinuclear nickel(II) complexes [Ni2(bomp)(MeCO2)2]BPh4 (1) and [Ni2(bomp)(PhCO2)2]BPh4 (2) were synthesized with the dinucleating ligand 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-methylphenol [H(bomp)]. X-Ray analysis revealed that the complex 1 · 0.5CHCl3 contains two nickel(II) ions bridged by phenolic oxygen and two acetate groups, forming a μ-phenoxo-bis(μ-acetato)dinickel(II) core. Electronic spectra were investigated for 1 and 2 in the range of 400–1800 nm, and the data were typical for the octahedral high-spin nickel(II) complexes. Obtained spectral components were well simulated based on the angular overlap model assuming the trigonally distorted octahedral geometry. Magnetic susceptibility was measured for 1 and 2 over a temperature range of 4.5–300 K. The optimized magnetic data were J = 1.75 cm−1, zJ′ = −0.234 cm−1, g = 2.21, D = 15.1 cm−1, and TIP = 370 × 10−6 cm−1 for complex 1 and J = 3.55 cm−1, zJ′ = −0.238 cm−1, g = 2.23, D = 21.8 cm−1, and TIP = 470 × 10−6 cm−1 for complex 2. The data revealed ferromagnetic interactions between the two nickel(II) ions.