title: Monomeric, trimeric, and tetrameric transition metal complexes (Mn, Fe, Co) containing N,N-bis(2-pyridylmethyl)-2-aminoethanol/-ate: preparation, crystal structure, molecular magnetism and oxidation catalysis.
abstract: The reaction of N,N-bis(2-pyridylmethyl)-2-aminoethanol (bpaeOH), NaSCN/NaN(3), and metal (M) ions [M = Mn(II), Fe(II/III), Co(II)] in MeOH, leads to the isolation of a series of monomeric, trimeric, and tetrameric metal complexes, namely [Mn(bpaeOH)(NCS)(2)] (1), [Mn(bpaeO)(N(3))(2)] (2), [Fe(bpaeOH)(NCS)(2)] (3), [Fe(4)(bpaeO)(2)(CH(3)O)(2)(N(3))(8)] (4), [Co(bpaeOH)(NCS)(2)] (5), and [Co(3)(bpaeO)(2)(NO(3))(N(3))(4)](NO(3)) (6). These compounds have been investigated by single crystal X-ray diffractometry and magnetochemistry. In complex 1 the Mn(II) is bonded to one bpaeOH and two thiocyanate ions, while in complex 2 it is coordinated to a deprotonated bpaeO(-) and two azide ions. The oxidation states of manganese ions are 2+ for 1 and 3+ for 2, respectively, indicating that the different oxidation states depend on the type of binding anions. The structures of monomeric iron(II) and cobalt(II) complexes 3 and 5 with two thiocyanate ions are isomorphous to that of 1. Compounds 1, 2, 3, and 5 exhibit high-spin states in the temperature range 5 to 300 K. 4 contains two different iron(III) ions in an asymmetric unit, one is coordinated to a deprotonated bpaeO(-), an azide ion, and a methoxy group, and the other is bonded to three azide ions and two oxygens from bpaeO(-) and a methoxy group. Two independent iron(III) ions in 4 form a tetranuclear complex by symmetry. 4 displays both ferromagnetic and antiferromagnetic couplings (J = 9.8 and -14.3 cm(-1)) between the iron(III) ions. 6 is a mixed-valence trinuclear cobalt complex, which is formulated as Co(III)(S = 0)-Co(II)(S = 3/2)-Co(III)(S = 0). The effective magnetic moment at room temperature corresponds to the high-spin cobalt(II) ion (∼4.27 μ(B)). Interestingly, 6 showed efficient catalytic activities toward various olefins and alcohols with modest to excellent yields, and it has been proposed that a high-valent Co(V)-oxo species might be responsible for oxygen atom transfer in the olefin epoxidation and alcohol oxidation reactions.
authors.affiliation: Department of Chemistry Graduate School, Kyungpook National University, Daegu, 702-701, Republic of Korea.
authors.forename: Jong Won
authors.initials: JW
authors.lastname: Shin
authors.forename: Sankara Rao
authors.initials: SR
authors.lastname: Rowthu
authors.forename: Min Young
authors.initials: MY
authors.lastname: Hyun
authors.forename: Young Joo
authors.initials: YJ
authors.lastname: Song
authors.forename: Cheal
authors.initials: C
authors.lastname: Kim
authors.forename: Bong Gon
authors.initials: BG
authors.lastname: Kim
authors.forename: Kil Sik
authors.initials: KS
authors.lastname: Min
mesh_terms: D002384:Catalysis; D003035:Cobalt / Q000737:chemistry; D056831:Coordination Complexes / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019856:Ethanolamine / Q000737:chemistry*; D004983:Ethanolamines / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D008280:Magnetics; D008345:Manganese / Q000737:chemistry; D008968:Molecular Conformation; D010084:Oxidation-Reduction; D011725:Pyridines / Q000737:chemistry*; D013696:Temperature; D028561:Transition Elements / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D004983:Ethanolamines; C560956:N,N-bis(2-pyridylmethyl)-2-aminoethanol; D011725:Pyridines; D028561:Transition Elements; D003035:Cobalt; D008345:Manganese; D019856:Ethanolamine; D007501:Iron