Calix[4]arene-Based Clusters with μ9-Carbonato-Bridged CoII9 Cores

Abstract

Two discrete complexes, [Co^II₉(TBC[4])₃(m₉-CO₃)(m-H₂O)₃(m₃-OH)₂(m-CH₃COO)₂(DMA)₄]•3H₂O•2CH₃OH (1), [Co^II₉(TBC[4])₃(m₉-CO₃)(m₃-OH)(m-HCOO)(O₃PPh)(DMF)₈]•2H₂O•CH₃OH (2) (TBC[4] = p-tert-butylcalix[4]arene, DMA = N,N'-dimethylacetamide, DMF = N,N'-dimethylformamide), have been solvothermally obtained and structurally characterized by single-crystal X-ray diffraction analyses and powder X-ray diffraction. Complex 1 capped by three TBC[4] ligands possesses a tri-capped trigonal prismatic Co^II₉ core housing a m₉-carbonato anion. When auxiliary phosphonate ligand is introduced into the reaction, complex 2 is obtained with an obvious geometrical change in the metallic core moving from a regular tri-capped trigonal prism in 1 to a distorted one in 2. What is more, this work represents the first two examples of m₉-CO₃^2- bridged paramagnetic metal clusters reported in the literature. Magnetic measurements reveal that both of the complexes show spin-glass behavior.