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, CHCO, Cl, NO), sodium azide (NaN), 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 CoCo: Co(HL)(AP)(N) (), [Co(HL)(µ-1,1,1-N)(µ-1,1-N)Cl(CHOH)]·4CHOH (), CoCo(HL)(µ-CHCO)(µ-OH)·2CHCHOH (), and CoCo (HL1)(THMAM) (). In , 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 , two cobalt(II) ions in a dinuclear unit are bridged through phenoxide O and μ-1,1,1-N azido bridges, and the two dinuclear units are interconnected by two μ-1,1-N and two μ-1,1,1-N azido bridges generating tetranuclear cationic [Co(HL)(µ-1,1,1-N)(µ-1,1-N)Cl(CHOH)] units with an incomplete double cubane core, which grow into polynuclear 1D-single chains along the -axis through H-bonding. In , HL holds mixed-valent Co(II)/Co(III) ions in a dinuclear unit bridged via phenoxide O, μ-1,3-CHCO, and μ-OH bridges, and the dinuclear units are interconnected through two deprotonated ethanolic O in the side arms of the ligands and two μ-OH bridges generating cationic tetranuclear [CoCo(HL)(µ-CHCO)(µOH)] units with an incomplete double cubane core. In , HL1 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-RO) of THMAM bridges producing centrosymmetric cationic tetranuclear [CoCo (HL1)(THMAM)] units which grow into 2D-sheets along the -axis through a network of H-bonding. Bulk magnetization measurements on demonstrate that the magnetic interactions are completely dominated by an overall ferromagnetic coupling occurring between Co(II) ions.