A Novel Polyoxometalate [Sb₅(OH)₁₀Mo₅O₂₆]^7-: From The Ratemate To Chiral Compounds

Chiral compounds have attracted considerable attention, not only because of their intriguing structures, but also due to their potential applications in nonlinear optics, enantioselective catalysis and medicine. In particular, studies on chiral POMs have become a rapidly developed area. The development of the family of original chiral POMs has become the key of studies on chiral POMs.In this thesis, a totally new type of chiral heteropolyanion, [Sb₅(OH)₁₀Mo₅O₂₆]^7-, has been isolated as racemic compound 1. The racemate was further resolved into enantiomerically pure crystals L-2 and R-2 by addition of organic units. Single-crystal structure analyses have confirmed the assignment of the resolution, as well as solution chiroptical properties of 2 using circular dichroism (CD) spectroscopy. ESI-MS investigations of the stability of 2 show that {Sb₅Mo₅} does not dissociate in neutral aqueous solution, but exists in the solution phase as the trimer {Sb₅Mo₅} (constructed from three L-{Sb₅Mo₅} or three R-{Sb₅Mo₅}). And ESI-MS studies of 1 reveal that {Sb₅Mo₅} exists in the solution phase as dimmers (one pairs of L-{Sb₅Mo₅} and R-{Sb₅Mo₅}) and tetramers (two pairs of L-{Sb₅Mo₅} and R-{Sb₅Mo₅}). We give the structures of these aggregates in the solution phase according to the solid state structures of 1, 2. Furthermore, in the absence of SnCl₄ and BuSnCl₃, with the same reaction conditions, we did not obtain 1 and 2, but achiral compound 3.Δ,Λ-(NH₄)₇[Sb₅(OH)₁₀Mo₅O₂₆]·5H₂O (1)Δ-(NH₄)₇[Sb₅(OH)₁₀Mo₅O₂₆]·12H₂O (L-2)Λ-(NH₄)₇[Sb₅(OH)₁₀Mo₅O₂₆]·12H₂O (R-2) (NH₄)₆[Sb₆(OH)₁₂Mo₄O₂₄]·12H₂O (3)...