Synthesis, crystal structures and intermolecular interactions of two Mn(II) complexes with 4,4′-bipy and methyl benzoates

Two manganese complexes containing 4,4′-bipyridine and methyl benzoate as ligands have been prepared and crystallized by solvent evaporation method in DMF. The single crystal X-ray crystallographic analyses reveal that the complexes crystallize in monoclinic system. Crystal of 1 [Mn2(4,4′-bipy)2 (o-MBA)4]n has space group of P21/c with unit cell parameters of a = 17.508 (Å), b = 11.6229 (Å), c = 27.983 (Å), β = 128.123°, V = 4.4797 nm3, empirical formula: C52H44Mn2N4O8, Mr = 962.79, Z = 4, Dc = 1.428 g/cm3, μ = 0.625 mm−1, and F(000) = 1992. The crystal of 2 [Mn (4,4′-bipy)(m-MBA)2]n belongs to space group C2/c with a = 16.079 (Å), b = 11.652 (Å), c = 24.887 (Å), β = 92.02°, V = 4.660 nm3, empirical formula: C26H22MnN2O4, Mr = 481.40, Z = 8, Dc = 1.372 g/cm3, μ = 1.179 mm−1, F(000) = 1992. The weak interactions in structures are observed from the X-ray crystallographic data. These include the CH⋯O hydrogen bonds, π–π stacking and CH⋯π interactions found in 1. The different strength of intermolecular interaction in the structures is reflected on their different thermal stability of the two complexes measured by thermal gravimetric analysis and the 2D-IR correlation spectroscopy. The study of weak interactions is meaningful to provide supporting data for potential application in molecular biology.

► Two manganese complexes with 1-D chains structure have been prepared and crystallized.
► The 2-D supermolecular systems are formed by weak interactions in the structure of two complexes.
► Relationships between weak interactions and the properties were studied by TGA and 2D-IR COS.
► The weak interactions are effective on the structural framework of complexes.
► The weak interactions also play an important role in the thermostability aspect.