Manganese(II) complexes with a bulky anthracene-based dicarboxylic ligand: Syntheses, crystal structures, and magnetic properties

To investigate the influence of the bulky aromatic ring skeleton with a large conjugated p-system on the structures and properties of its complexes, two Mn-II 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: {[Mn-2(L)(2)(bipy)(2)(H2O)(2)]}(infinity) (1) and {[Mn(L)(phen)(2)](H2O)(2.5)}(infinity) (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 forma three-dimensional (3D) supramolecular network by the co-effects of C-H center dot center dot center dot pi and O-H center dot center dot center dot 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 center dot center dot center dot pi 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 center dot center dot center dot 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.