Crystal structure, assembly process, and single-molecule magnet behavior of a triangular prismatic {Co 9 } cluster.

Using the polydentate ligand of H 4 L with the Co II ion, a triangular prism-type nine-nucleus cluster [Co 9 (L) 3 (CH 2 OCH 2 OH) 6 ]·3.5H 2 O ({Co9}-Eg, H 4 L = 6,6'-(1 H ,1' H -[3,3'-bi(1,2,4-triazole)]-5,5'-diyl)dipicolinic acid) was constructed. Ion fragmentation during the formation of the {Co9}-Eg cluster was tracked using time-dependent electrospray ionization mass spectrometry. In addition, we proposed two possible formation processes (i) H 4 L → CoL → Co 2 L → Co 6 L 3 → Co 7 L 3 → Co 9 L 3 and (ii) H 4 L → CoL → Co 2 L → Co 3 L → Co 5 L 2 → Co 7 L 3 → Co 9 L 3 . Magnetic studies show that {Co9}-Eg exhibits slow relaxation under a static zero field at low temperature, which is the main characteristic of single molecule magnets (SMMs).