title: Scalar coupling across [C-H···F-C] interactions in (σ-aryl)-chelating post-metallocenes.
abstract: The nature and importance of C-H···F-C interactions is a topical yet controversial issue, and the development of spectroscopic methods to probe such contacts is therefore warranted. A series of Group 4 bis(benzyl) complexes supported by (σ-aryl)-2-phenolate-6-pyridyl [O,C,N-R(1)] ligands bearing a fluorinated R(1) group (CF(3) or F) in the vicinity of the metal has been prepared. The X-ray crystal structure of the CF(3)-substituted Hf derivative features intramolecular C-H···F-C and Hf···F-C contacts. All complexes have been characterized by multinuclear NMR spectroscopy. The (1)H and (13)C NMR spectra of [M(O,C,N-CF(3))(CH(2)Ph)(2)] derivatives display coupling (assigned to (1h)J(HF) and (2h)J(CF) for Ti; (3)J(HF) and (2)J(CF) (through M···F) for Hf and Zr) between the benzyl CH(2) and CF(3) moieties. [(1)H,(19)F]-HMBC NMR experiments have been performed for the M-[O,C,N-R(1)] complexes and their [O,N,C] counterparts, revealing significant scalar coupling across the C-H···F-C interactions for Ti-[O,C,N] and [O,N,C] species.
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, PR China.
authors.forename: Loi-Chi
authors.initials: LC
authors.lastname: So
authors.forename: Cham-Chuen
authors.initials: CC
authors.lastname: Liu
authors.forename: Michael C W
authors.initials: MC
authors.lastname: Chan
authors.forename: Jerry C Y
authors.initials: JC
authors.lastname: Lo
authors.forename: Kong-Hung
authors.initials: KH
authors.lastname: Sze
authors.forename: Nianyong
authors.initials: N
authors.lastname: Zhu
mesh_terms: D002244:Carbon / Q000737:chemistry; D002614:Chelating Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005461:Fluorine / Q000737:chemistry*; D006860:Hydrogen Bonding; D008024:Ligands; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D008024:Ligands; D009942:Organometallic Compounds; C013108:metallocene; D005461:Fluorine; D002244:Carbon