| Summary: | Two new dicarboxylate-based three-dimensional cobalt coordination polymers, [Co(Me<sub>2</sub>mal)(bpe)<sub>0.5</sub>(H<sub>2</sub>O)]<i><sub>n</sub></i> (<b>1</b>) and [Co(Me<sub>2</sub>mal)(bpe)<sub>0.5</sub>]<i><sub>n</sub></i> (<b>2</b>), were synthesized from dimethylmalonic acid (H<sub>2</sub>-Me<sub>2</sub>mal) in temperature-controlled solvothermal reactions. Lower temperatures (60−80 °C) favored the formation of <b>1</b>, while higher temperatures (120 °C) favored the production of <b>2</b>. Compound <b>1</b> is comprised of Co(II) corrugated layers linked by <i>syn</i>−<i>anti</i> carboxylate bridges from the Me<sub>2</sub>mal<sup>2−</sup> ligands and pillared through <i>bis</i>-monodentate bpe groups. Compound <b>2</b> is comprised of a three-dimensional network involving one-dimensional Co−carboxylate chains bonded by antisymmetric µ<sub>4</sub>-Me<sub>2</sub>mal<sup>2−</sup> ligands and aligned parallel to the [001] direction. The solvothermal retreatment of crystalline samples of <b>1</b> in a DMF/H<sub>2</sub>O solvent at 120 °C allowed the structural reassembly, with complete conversion within <b>2</b> over 48 h. Magnetic analyses revealed that compound <b>1</b> exhibits both spin-orbital coupling and antiferromagnetic interactions through a <i>syn</i>−<i>anti</i> carboxylate (Me<sub>2</sub>mal<sup>2−</sup>) bridge exchange pathway [Co−Co separation of 5.478 Å] and compound <b>2</b> showed a ferromagnetic interaction resulting from the short Co−Co separation (3.150 Å) and the small Co−O−Co bridging angles (98.5° and 95.3°) exchange pathway which was provided by µ<sub>4</sub>-Me<sub>2</sub>mal<sup>2−</sup> bridging ligand.
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