Manganese(II) Complexes with a Bulky Anthracene-Based Dicarboxylic Ligand: Syntheses, Crystal Structures, and Magnetic Properties

Abstract

To investigate the influence of the bulky aromatic ring skeleton with a large conjugated π-system on the structures and properties of its complexes, two MnII complexes with the anthracene-based dicarboxylic ligand anthracene-9,10-dicarboxylic acid (H2L) and different 2,2′-bipyridyl-like chelating ligands were synthesized and characterized: {[Mn2(L)2(bipy)2(H2O)2]}∞ (1) and {[Mn(L)(phen)2](H2O)2.5}∞ (2) (L = anthracene-9,10-dicarboxylate, bipy = 2,2′-bipyridine, and phen = 1,10-phenanthroline). Complex 1 has a (4,4) two-dimensional (2D) sheet structure that is further assembled to form a three-dimensional (3D) supramolecular network by the co-effects of C–H···π and O–H···O hydrogen-bonding interactions. Complex 2 adopts a one-dimensional (1D) polymeric chain structure by using the chelating phen instead of bipy in 1, which is further interlinked by interchain C–H···π interactions, which results in a higher-dimensional supramolecular network from the different crystallographic directions. The relevant results reveal that the steric bulk of the anthracene ring in H2L may play an important role in the formation of 1 and 2. Moreover, the magnetic properties of 1 and 2 show that the long Mn···Mn intermetallic separations result in weak magnetic coupling, along with the corresponding coupling constant J parameters related to their structural characteristics, –0.35 cm–1 for 1 and –3.0 cm–1 for 2.