title: Squeezing fluoride out of water with a neutral bidentate antimony(V) Lewis acid.
abstract: Because of hydration, fluoride ions in water typically elude complexation by neutral Lewis acids. Here, we show how this limitation can be overcome with a bidentate Lewis acid containing two antimony(V) centers. This derivative (2) is obtained by the simple reaction of 4,5-bis(diphenylstibino)-9,9-dimethylxanthene (1) with two equivalents of 3,4,5,6-tetrachlorobenzoquinone (o-chloranil). It features two square-pyramidal stiborane units oriented in a face-to-face fashion. Titration experiments show that this new bidentate Lewis acid binds fluoride in aqueous solutions containing 95% water with a binding constant (K) of 700±30 M(-1). The structure of the fluoride adduct confirms fluoride anion chelation between the two antimony centers.
authors.affiliation: Department of Chemistry, Texas A&M University, College Station, TX 77843 (USA) http://www.chem.tamu.edu/rgroup/gabbai/
authors.forename: Masato
authors.initials: M
authors.lastname: Hirai
authors.forename: François P
authors.initials: FP
authors.lastname: Gabbaï
keywords: Lewis acids; antimony; fluoride; hypervalent compounds; main group elements