Diverse Structures Based on a Heptanuclear Cobalt Cluster with 0D to 3D Metal-Organic Frameworks: Magnetism and Application in Batteries.

Polymetallic complexes with interesting multifunctions have attracted extensive investigation. Synthesized through the use of different cobalt salt anions and solvents, five complexes, namely [Co Co (H L) Cl (MeOH)] (1), [Co Co (H L) (CH COO) (HCOO)⋅H O] (2), [Co Co (H L) (HCOO) (NO )⋅2H O] (3), [Co Co (H L) (bda)(CH COO) ⋅2H O] (4), and [Co Co (H L) (ipa)(HCOO) (dmf)⋅H O] (5) (H L=bis-tris propane; BDA=biphenyl-4,4'-dicarboxylic acid; IPA=isophthalic acid; DMF=N,N-dimethylformamide), based on the heptanuclear {Co Co } cluster with structures from 0D to 3D metal-organic frameworks (MOFs) have been solvothermally synthesized. Compound 1 is the first 0D heptanuclear cluster based on H L. Compound 2 crystallizes in the chiral space group P2 2 2 and consists of a 1D chiral helical chain. Complex 3 exhibits a 3D network structure. Compound 4 possesses a 1D zigzag-like chain structure. Finally, compound 5 was obtained as a 3D microporous structure. Compounds 1, 3, and 4 display dominant ferrimagnetic interactions whereas compounds 2 and 5 exhibit antiferromagnetic interactions. Moreover, the Co O prepared by calcining compound 2 presents a reversible capacity of 1122.9 mA h g at 0.2 A g after 100 cycles and an excellent rate capability, which suggests that coordination compounds with a 1D chain structure are outstanding precursors for preparing anode materials for lithium ion batteries.