One-Pot Self-Assembly of Dinuclear, Tetranuclear, and H-Bonding-Directed Polynuclear Cobalt(II), Cobalt(III), and Mixed-Valence Co(II)/Co(III) Complexes of Schiff Base Ligands with Incomplete Double Cubane Core

The reaction of 2,6-diformyl-4-methylphenol (DFMF) with 1-amino-2-propanol (AP) and tris(hydroxymethyl)aminomethane (THMAM) was investigated in the presence of Cobalt(II) salts, (X = ClO(4)(−), CH(3)CO(2)(−), Cl(−), NO(3)(−)), sodium azide (NaN(3)), and triethylamine (TEA). In one pot, the variation in Cobalt(II) salt results in the self-assembly of dinuclear, tetranuclear, and H-bonding-directed polynuclear coordination complexes of Cobalt(III), Cobalt(II), and mixed-valence Co(II)Co(III): [Co(2)(III)(H(2)L(−)(1))(2)(AP(−)(1))(N(3))](ClO(4))(2) (1), [Co(4)(H(2)L(−)(1))(2)(µ(3)-1,1,1-N(3))(2)(µ-1,1-N(3))(2)Cl(2)(CH(3)OH)(2)]·4CH(3)OH (2), [Co(2)(II)Co(2)(III)(HL(−)(2))(2)(µ-CH(3)CO(2))(2)(µ(3)-OH)(2)](NO(3))(2)·2CH(3)CH(2)OH (3), and [Co(2)(II)Co(2)(III) (H(2)L1(2)(−))(2)(THMAM(−1))(2)](NO(3))(4) (4). In 1, two cobalt(III) ions are connected via three single atom bridges; two from deprotonated ethanolic oxygen atoms in the side arms of the ligands and one from the1-amino-2-propanol moiety forming a dinuclear unit with a very short (2.5430(11) Å) Co-Co intermetallic separation with a coordination number of 7, a rare feature for cobalt(III). In 2, two cobalt(II) ions in a dinuclear unit are bridged through phenoxide O and μ(3)-1,1,1-N(3) azido bridges, and the two dinuclear units are interconnected by two μ-1,1-N(3) and two μ(3)-1,1,1-N(3) azido bridges generating tetranuclear cationic [Co(4)(H(2)L(−)(1))(2)(µ(3)-1,1,1-N(3))(2)(µ-1,1-N(3))(2)Cl(2)(CH(3)OH)(2)](2+) units with an incomplete double cubane core, which grow into polynuclear 1D-single chains along the a-axis through H-bonding. In 3, HL(2−) holds mixed-valent Co(II)/Co(III) ions in a dinuclear unit bridged via phenoxide O, μ-1,3-CH(3)CO(2)(−), and μ(3)-OH(−) bridges, and the dinuclear units are interconnected through two deprotonated ethanolic O in the side arms of the ligands and two μ(3)-OH(−) bridges generating cationic tetranuclear [Co(2)(II)Co(2)(III)(HL(−)(2))(2)(µ-CH(3)CO(2))(2)(µ(3-)OH)(2)](2+) units with an incomplete double cubane core. In 4, H(2)L1(−2) holds mixed-valent Co(II)/Co(III) ions in dinuclear units which dimerize through two ethanolic O (μ-RO(−)) in the side arms of the ligands and two ethanolic O (μ(3)-RO(−)) of THMAM bridges producing centrosymmetric cationic tetranuclear [Co(2)(II)Co(2)(III) (H(2)L1(−)(2))(2)(THMAM(−1))(2)](4+) units which grow into 2D-sheets along the bc-axis through a network of H-bonding. Bulk magnetization measurements on 2 demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Co(II) ions.