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 [Co-2(bhmp)(OAc)(2)]BPh4 (1) and [Co-2(bhmp)(OBz)(2)]BPh4 (2). The complex 1(.)2.5CH(3)CN (C50H62.5BCo2N4.5O9) crystallizes in the monoclinic space group C2/c with dimensions a = 25.424(5) Angstrom, b = 13.376(2) Angstrom, c = 29.913(6) Angstrom, beta = 105.930(3)degrees, and V = 9781(3) Angstrom(3) and with Z = 8. X-ray diffraction analysis revealed a mu-phenoxo-bis (mu-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 k = 0.77,lambda = -116 cm(-1), Delta = 572 cm(-1), and J = -0.44 cm(-1) for complex 1 and k = 0.96, lambda = -93 cm(-1), A 616 cm-1, and J = -0.33 cm(-1) for complex 2.