Synthesis, Structure, and Magnetic Study of Two Tridecanuclear Planar Cobalt Clusters with Unique Core Geometries

The reaction of Co(NO 3 ) 2 · 6H 2 O with N , N ‐diethanolamine (H 2 L1 ) in the presence of sodium acetate, using triethylamine as a base, leads to a tridecanuclear mixed‐valent cobalt cluster [Co II 9 Co III 4 (OH) 6 (H 2 O) 2 ( L1 ) 8 (OAc) 4 ](NO 3 ) 4 · 24H 2 O ( 1 ). Similar reaction with a newly designed hydroxy‐ and nitrogen‐rich chelating ligand 2‐[bis(pyridin‐2‐ylmethyl)amino]‐2‐(hydroxymethyl)propane‐1,3‐diol (H 2 L2 ) gives a mixed‐valent Co 13 cluster [Co II 7 Co III 6 (OH) 12 ( L2 ) 6 ](NO 3 ) 8 · 10H 2 O ( 2 ). The cobalt ions in both 1 and 2 are nearly coplanar, forming a novel shieldlike configuration for 1 and a unique hexagram structure for 2 , both of which have not been observed for the polynuclear cobalt clusters. The magnetic susceptibility investigation showed that complexes 1 and 2 exhibited ferromagnetic coupling between Co II ions. Further magnetic studies revealed a slight frequency dependence of 2 , which suggests that 2 might be a single‐molecule magnet.