A dinuclear vanadium compound with 24-membered macrocycle generated via formation of S–C bonds

A dinuclear vanadium 24-membered macrocycle with double-ring, [V2O2L2(μ-CH3COO)]− (H2L = 3,3′-(1,3,4-thiadiazole-2,5-diyl)bis(sulfane-diyl) bis(4-hydroxypent-3-en-2-one)), was prepared in high yield from the reaction of VO2(acac) with 2,5-dimercapto-1,3,4-thiadiazole dipotassium salt (K2SSS) and acetylacetone (Hacac) at room temperature. Its closure of 24-membered macrocycle has resulted from the formation of U-shape units via S–C bonding between original SSS2− and acac− ligands, while the bridging CH3COO− has created from an unexpected decomposition of Hacac. The obtained two products were characterized by single crystal X-ray diffraction, XRD, ESR, TGA and magnetism analyses. A possible mechanism for formation of the bimetal 24-membered macrocycle has been discussed.