Hierarchical Assembly of a {Co24} Cluster from Two Vertex-Fused {Co13} Clusters and Their Single-Molecule Magnetism

Inorg Chem. 2018 Aug 6;57(15):9182-9189. doi: 10.1021/acs.inorgchem.8b01211. Epub 2018 Jul 9.

Abstract

We present the synthesis, structural characterization, and magnetic properties of two high-nuclearity cobalt clusters formulated as [Co133-OH)33-Cl)(dpbt)5(ptd)Cl10][Co(H2O)2Cl2]·(CH3)2CHOH (1) and [Co243-OH)63-Cl)2(dpbt)10(ptd)2Cl16]·2CH3CH2OH (2), respectively (H2dpbt = 5,5'-bis(pyridin-2-yl)-3,3'-bis(1,2,4-triazole) and H2ptd = 3-(pyridin-2-yl)-1,2,4-triazine-5,6-diol). Compound 1 is composed of an inner [Co43-OH)33-Cl)] cubane and an outer [Co9(dpbt)5(ptd)Cl10] defective adamantane. Compound 2 reveals a giant {Co24} cluster possessing a dual-[Co12] skeleton from 1. The hierarchical assembly from 1 to 2 has been established and tracked through high-resolution electrospray ionization (HRESI-MS) analyses from the solvothermal reaction mother solution. Magnetic studies of 1 and 2 revealed the highly correlated spins, a glasslike magnetic phase transition at ca. 8 K, and slow relaxation behavior of SMM nature in the lower-temperature region (below 4 K).