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As part of our efforts in the chemistry of main group platforms that support anion sensing and transport, we are now reporting the synthesis of anitmony-based bidentate Lewis acids featuring the o -C 6 F 4 backbone. These compounds can be easily accessed by reaction of the newly synthesized o -C 6 F 4 (SbPh 2 ) 2 ( 5 ) with o -chloranil or octafluorophenanthra-9,10-quinone, affording the corresponding distiboranes 6 and 7 of general formula o -C 6 F 4 (SbPh 2 (diolate)) 2 with diolate = tetrachlorocatecholate for 6 and octafluorophenanthrene-9,10-diolate for 7 , respectively. While 6 is very poorly soluble, its octafluorophenanthrene-9,10-diolate analog 7 readily dissolves in CH 2 Cl 2 and undergoes swift conversion into the corresponding fluoride chelate complex [ 7 -μ 2 -F] − which has been isolated as a [ n Bu 4 N] + salt. The o -C 6 H 4 analog of 7 , referred to as 8 , has also been prepared. Although less Lewis acidic than 7 , 8 also forms a very stable fluoride chelate complex ([ 8 -μ 2 -F] − ). Altogether, our experiental results, coupled with computational analyses and fluoride anion affinity calculations, show that 7 and 8 are some of the strongest antimony-based fluoride anion chelators prepared to date. Another notable aspect of this work concerns the use of the octafluorophenanthrene-9,10-diolate ligand and its ablity to impart advantageous solubility and Lewis acidity properties. 

With the view of developing electrophilic late-transition-metal catalysts, we have now synthesized [(o-(Ph2P)C6H4)2Sb(OTf)2]Pt(OTf) (2) and [(o-(iPr2P)C6H4)2Sb(OTf)2]Pt(OTf) (4) by treatment of the corresponding trichlorides ([(o-(R2P)C6H4)2SbCl2]PtCl (R = Ph, iPr)) with 3 equiv of AgOTf. The crystal structures of 2 and 4 confirmed that the chloride ligands have been fully substituted by more labile triflate ligands. Despite structural similarities in the dinuclear cores of 2 and 4, only 2 acts as a potent carbophilic catalyst in enyne cyclization reactions. The high activity of 2 is also reflected by its ability to promote the addition of pyrrole and thiophene derivatives to alkynes. Structural and computational analyses suggest that the superior reactivity of 2 results from both favorable steric and electronic effects. Finally, a comparison of 2 with the previously reported self-activating catalyst [(o-(Ph2P)C6H4)2Sb(OTf)2]PtCl underscores the benefits of triflate for chloride substitution.