Ligand-Directed Assembly of a Series of Complexes Bearing Thiourea-Based Carboxylates

Three interesting copper complexes, {[CuI6CuII6L16(H2O)3(CH3OH)6]·5H2O·3CH3OH}n (2), [CuI6CuII6L26(H2O)10]n (3), and [Cu3L32(CH3OH)4] (4) [H3L1 = 2-(3-benzoylthioureido)ethanoic acid, H3L2 = 2-(3-benzoylthioureido)propionic acid, H3L3 = 2-(3-benzoylthioureido)benzoic acid], have been synthesized and characterized by single-crystal X-ray diffraction, XPS, elemental analyses, EPR, and IR spectra. Polymer 2 was synthesized by the reaction of single crystals of {[Ln2(H2L1)4(Phen)2(NO3)2]·CH3OH} [Ln = Pr (1a), Nd (1b), or Ho (1c), Phen = 1,10-phenanthroline] with Cu(OAc)2 in aqueous DMF. Compounds 3 and 4 were prepared by Cu(OAc)2 directly reacting with H3L2 or H3L3 in solution, respectively. Complexes 2 and 3 are rare 2D cluster polymers containing unique mixed-valence [CuI6CuII6L16] or [CuI6CuII6L26] subunits. Compound 4 is a trinuclear copper(II) complex, in which two triply deprotonated (L3)3– ligands bridge three Cu2+ ions. The theoretical predication of the substituent effect of the three triply deprotonated ligands (L1)3–, (L2)3–, and (L3)3– has been presented. The thermal properties of complexes 2–4 have been determined as well. Also, it is discovered that there exists weak antiferromagnetic coupling between the neighboring Cu(II) ions in 2, 3, or 4, respectively; the best fittings to the experimental magnetic susceptibilities gave J = −1.63 cm–1 and g = 2.14 for 3 and J = −12.06 cm–1, J′ = −0.01 cm–1, and g = 2.21 for 4.