Synthesis, structure, and supramolecular architecture of benzonitrile and pyridine adducts of bis(pentafluorophenyl)zinc: Pentafluorophenyl-aryl interactions versus homoaromatic pairing

Treatment of (C6F5)(2)Zn(toluene) with 2 equiv of a series of benzonitrile or pyridine derivatives yielded the complexes (C6F5)(2)Zn(L)(2) (where L = benzonitrile, 4-(phenyl)benzonitrile, 4-(N-pyrrolyl)benzonitrile, pyridine, 4-(phenyl)pyridine, and 4-(N-pyrrolyl)pyridine). The four-coordinate solution-phase nature of these complexes was confirmed by a series of variable-temperature F-19 NMR experiments and comparison to (C6F5)(2)Zn(2,2'-bipy). The solvent-free solid-state structures of each of the four-coordinate adducts and the toluene solvate of (C6F5)(2)Zn(NCC6H4C6H5)(2) were determined by single-crystal X-ray diffraction and have distorted tetrahedral geometries. Analysis of the crystal packing revealed a preponderance of offset face-to-face homo-aryl and embrace-like interactions over the hetero-aryl, pentafluorophenyl-phenyl, interaction. These aryl-aryl synthons serve to assemble paired, one- and three-dimensional supramolecular architectures.