Complexation of Diphenyl(tetrafluoroborato)-l3-iodane with Pyridines

Diphenyl(tetrafluoroborato)-λ 3 -iodane forms 1:1 complexes with pyridine-derived ligands in CD 2 Cl 2 solution and the binding constants decrease in the order: 1,10-phenanthroline > 2,2':6',2"-terpyridine > 2,2'-bipyridyl ≈ pyridine.The 1:1 complex of the λ 3 -iodane with pyridine adopts a distorted square-planar geometry around the iodine atom.Recently we found that crown ethers serve as efficient ligands for organo-λ 3 -iodanes.18-Crown-6 (18C6) forms a discrete complex with diphenyl(tetrafluoroborato)-and ethynyl(phenyl)(tetrafluoroborato)-λ 3iodanes, in which the iodine(III) atoms contact with the three adjacent oxygen atoms of 18C6 through two hypervalent secondary bonding and a weak interaction. 1 The complexation with 18C6 increases the stability of labile λ 3 -iodanes.Thus, the thermally unstable hydroxy(phenyl)(tetrafluoroborato)-λ 3 -iodane 2 that decomposes at room temperature within a few minutes forms a stable crystalline crown ether complex. 3 contrast, synthesis and characterization of λ 3 -iodane complexes coordinated by neutral nitrogen ligands are very limited, probably because of the facile oxidation of amino groups by λ 3 -iodanes. 4Weiss and Seubert prepared [bis(trifluoromethanesulfonyloxy)iodo]benzene•(pyridine) 2 complex (1) with highly increased oxidation power by the reaction of (diacetoxyiodo)benzene with pyridine in the presence of trimethylsilyl trifluoromethanesulfonate. 5 Stable 1:1 complex (2) of benziodoxole with pyridine was synthesized by Zhdankin and co-workers. 6Detailed structures of these interesting pyridine complexes, however, are not available, because of the lack of the solid state structure analyses.We have reported the synthesis and solid state structure of 1:1 complex (3) of diphenyl(tetrafluoroborato)-λ 3 -iodane with 1,10-