Syntheses, crystal structures and magnetic properties of two adamantane-1,3-dicarboxylato bridged cobalt(II) phenanthroline complexes

Two adamantane-1,3-dicarboxylato bridged cobalt(II) phenanthroline complexes [Co2(H2O)2(phen)2(adc)2]·(C2H7N)·2H2O (1) and [Co(H2O)(phen)(adc)]·H2O (2) were synthesized in a mixed solvent under 45 °C (H2adc = adamantane-1,3-dicarboxylic acid). Compound 1 consists of dinuclear [Co2(H2O)2(phen)2(adc)2] complex molecules, dimethylamine (C2H7N) molecules and hydrogen-bonded water molecules. The dinuclear molecules, via intermolecular hydrogen bonds, are interconnected into hydrogen-bonded chains along [1 0 0] and interdigitation of phen ligands due to interchain π⋯π stacking interactions assembles the hydrogen-bonded chains into 2D supramolecular layers parallel to (0 0 1). In compound 2, the Co(II) ions are bridged by adamantane-1,3-dicarboxylate anions to form 1D chains along [0 0 1], and the resulting chains are assembled into double-chains based on interchain π⋯π interactions. The double-chains are further held together via hydrogen bonds into 2D supramolecular layers parallel to (1 0 0). The variable temperature magnetic measurements show an overall weak antiferromagnetic behavior for 1, and an weak ferromagnetic behavior over 300–75 K followed by antiferromagnetic behavior below 75 K for 2.