Mono- and dinuclear manganese(II) complexes derived from the cis/trans isomers of 2,4,5-tris(2-pyridyl)-4,5-dihydroimidazole

Two new manganese(II) complexes, [Mn(L1)(L1H)(ClO4)(H2O)][ClO4]2·0.5CH3CN·H2O (1) [L1 = trans-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine)] and [Mn2(μ-L2)2(H2O)3(CH3CN)3][ClO4]4·2CH3CN (2) [L2 = cis-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine)], have been prepared and examined by single-crystal X-ray diffraction analysis, showing that complex 1 is a mononuclear compound, whereas complex 2 is a dinuclear species. The cis/trans isomers L1 and L2 have similar coordination properties, but behave as bidentate and tridentate chelating ligands, respectively, giving distorted octahedral metal coordination geometries. X-ray diffraction studies revealed that the molecular and crystal structures are stabilized by a series of intra- and intermolecular interactions. In both cases extended supramolecular networks are generated, in compound 1 through O–H···O, O–H···N, N–H···O, N–H···N, C–H···O, C–H···N, C–H···π and π···π interactions, and in compound 2 through O–H···O, O–H···N, C–H···O and π···π interactions. The observed structural differences between the two metal complexes might be a consequence of these stabilizing effects.

In manganese(II) complexes of ligands trans-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine (L1) and cis-(±)2-(2,5-di(pyridin-2-yl)-4,5-dihydro-1H-imidazol-4-yl)pyridine) (L2), L1 and L2 behave as bidentate and tridentate chelating ligands, respectively, giving distorted octahedral coordination geometries. X-ray diffraction studies revealed a series of O–H···O, O–H···N, N–H···O, N–H···N, C–H···O, C–H···N, C–H···π and π···π in 1 giving 2D networks in the crystal lattice.Figure optionsDownload as PowerPoint slide