Preparation, Crystal Structure and Magnetic Properties of Two 1,2-Di(4-pyridyl)ethylene-Bridged Manganese(II) Complexes

Abstract

Two polymeric carboxylato-bridged manganese(II) complexes, \( {}_{\infty }^{1} \)[Mn(bpe)(NBA)2] (1) and \( {}_{\infty }^{1} \)[Mn(bpe)(MBA)2] (2) (bpe = 1,2-di(4-pyridyl)ethylene; HNBA = m-nitrobenzoic acid; HMBA = m-methyl-benzoic acid), were synthesized and characterized. Compounds 1 and 2 are isostructural. X-ray diffraction studies show that the title compounds possess a double chain structure. The chains in 1 and 2 are assembled into 2-D layers via C–H···O hydrogen bonds interactions. Furthermore, owing to the offset face-to-face π–π stacking interactions, the adjacent 2-D layers embed into each other to form a 3-D supramolecular framework. Variable-temperature (2–300 K) magnetic susceptibility measurements show the presence of weak antiferromagnetic interactions between the high-spin Mn(II) (S = 5/2) ions through a carboxylato bridge with the best fit parameters for 1 being J = −0.13 cm−1, zJ′ = −0.098 cm−1 and for 2, J = −0.33 cm−1, zJ′ = −0.001 cm−1.