Synthesis, Structure, and Magnetic Properties of Dinuclear Cobalt(II) Complexes with a New Phenol-Based Dinucleating Ligand with Four Hydroxyethyl Chelating Arms

A new end-off type acyclic ligand with four hydroxyethyl arms, 2,6-bis[bis(2-hydroxyethyl)aminomethyl]-4-methylphenol
[H(bhmp)], formed dinuclear cobalt(II) complexes [Co2(bhmp)(OAc)2]BPh4 (1) and [Co2(bhmp)(OBz)2]BPh4 (2). The
complex 1·2.5CH3CN (C50H62.5BCo2N4.5O9) crystallizes in the monoclinic space group C2/c with dimensions a =
25.424(5) Å, b = 13.376(2) Å, c = 29.913(6) Å, β = 105.930(3)°, and V = 9781(3) Å3 and with Z = 8. X-ray
diffraction analysis revealed a μ-phenoxo−bis(μ-acetato)dicobalt(II) core structure containing two octahedral cobalt(II) ions. Electronic spectra were investigated for 1 and 2 in the range 400−1800 nm, and the data were typical for
the octahedral high-spin cobalt(II) complexes. Magnetic susceptibility was measured for 1 and 2 over the temperature
range 4.5−300 K, and the data were analyzed well using our theoretical method. The best fitting parameters were
κ = 0.77, λ = −116 cm-1, Δ = 572 cm-1, and J = −0.44 cm-1 for complex 1 and κ = 0.96, λ = −93 cm-1,
Δ = 616 cm-1, and J = −0.33 cm-1 for complex 2.