Synthetic study of the ternary copper(II)/maleamate(-1)/1,10-phenanthroline reaction system: Mononuclear, dinuclear and polymeric complexes

The use of the maleamic acid (H2L)/1,10-phenathroline “blend” in copper(II) chemistry has yielded mononuclear and dinuclear complexes, and one coordination polymer. The chemical and structural identity of the products depends on the solvent, the absence or presence of external hydroxides in the reaction mixtures, the nature of the inorganic anion present in the copper(II) starting material and the molar ratio of the reactants. The maleamato(-1) complexes [Cu2(HL)3(phen)2](NO3) (2, 7), [Cu(HL)(phen)2](OH) (3), [Cu(HL)2(phen)] (4) and [Cu(HL)(NO3)(phen)]n (8) have been prepared and structurally characterized. The dinuclear cations 2 and 7 are structurally similar to the cation of complex [Cu2(HL)3(phen)2](ClO4) (1) which was previously communicated. The maleamato(-1) ligand adopts a variety of coordination modes in the above complexes, ranging from the familiar syn,syn η1:η1:μ2 bridging mode and the rare monoatomic bridging (η1:μ2) mode in the structures of 2 and 7, to the terminal monodentate in the structures of 3 and 4. Complex 8 is a 1D, zigzag coordination polymer in which the carboxylato group of the HL− ligand is asymmetrically coordinated to two CuII ions adopting the syn,anti η1:η1:μ2 mode; the amide O atom is also coordinated, thus forming an unusual 7-membered chelating ring. The crystal structures of the complexes are stabilized by a variety of H-bonding patterns which lead to interesting supramolecular architectures. Characteristic IR bands of the complexes are discussed in terms of the known structures, and the coordination modes of the HL− ligand.

The simultaneous employment of the maleamate(-1) and 1,10-phenanthroline ligands in copper(II) chemistry leads to mononuclear, dinuclear and polymeric complexes with interesting molecular and crystal structures.Figure optionsDownload as PowerPoint slide