title: Chelation-assisted carbon-halogen bond activation by a rhodium(I) complex.
abstract: Chelation-assisted activation of C-X bonds (X = Cl, Br, and I) took place in the reaction of [Rh(PPh(3))(2)(acetone)(2)](+) and 2-(2-halophenyl)pyridine or 10-halobenzo[h]quinoline. A series of 16-electron five-coordinate cationic rhodium(III) monohalide complexes was synthesized at room temperature. Neutral octahedral rhodium(III) dihalide complexes were obtained when the corresponding cationic monohalide complexes were further heated in acetone. Rhodium and iridium diiodides with these cyclometalation motifs could be alternatively synthesized from the reaction of the corresponding cyclometalated hydride complexes and I(2). X-ray crystal structures of representative monohalide and dihalide complexes are reported. Octahedral rhodium(III) dihalide complexes are active catalysts for the dimerization of terminal alkynes, while 16-electron cationic rhodium(III) monohalides are inactive.
authors.affiliation: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Chen
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Li
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Xingwei
authors.initials: X
authors.lastname: Li
mesh_terms: D000114:Acetylene / Q000031:analogs & derivatives / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D019281:Dimerization; D006219:Halogens / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry*
chemical_list: D002614:Chelating Agents; D006219:Halogens; C044736:phenylacetylene; D002244:Carbon; D012238:Rhodium; D000114:Acetylene